Introduction to nonlinear acoustics
Bjørnø, Leif
2010-01-01
A brief review of the basic principles of fluid mechanics needed for development of linear and nonlinear ultrasonic concepts will be given. The fundamental equations of nonlinear ultrasonics will be derived and their physical properties explained. It will be shown how an originally monochromatic finite-amplitude ultrasonic wave, due to nonlinear effects, will distort during its propagation in time and space to form higher harmonics to its fundamental frequency. The concepts of shock formation will be presented. The material nonlinearity, described by the nonlinearity parameter B/A of the material, and the convective nonlinearity, described by the ultrasonic Mach Number, will be explained. Two procedures for determination of B/A will briefly be described and some B/A-values characterizing biological materials will be presented. Shock formation, described by use of the Goldberg Number,and Ultrasonic Saturation will be discussed.. An introduction to focused ultrasonic fields will be given and it will be shown how the ultrasonic intensity will vary axially and laterally in and near the focal region and how the field parameters of interest to biomedical applications may be described by use of the KZK-Model. Finally, an introduction will be given to the parametric acoustic array formed by mixing and interaction of two monochromatic, finite-amplitude ultrasonic waves in a liquid and the potentials of this mixing process in biomedical ultrasound will briefly be mentioned.
Acoustic-gravity nonlinear structures
Directory of Open Access Journals (Sweden)
D. Jovanović
2002-01-01
Full Text Available A catalogue of nonlinear vortex structures associated with acoustic-gravity perturbations in the Earth's atmosphere is presented. Besides the previously known Kelvin-Stewart cat's eyes, dipolar and tripolar structures, new solutions having the form of a row of counter-rotating vortices, and several weakly two-dimensional vortex chains are given. The existence conditions for these nonlinear structures are discussed with respect to the presence of inhomogeneities of the shear flows. The mode-coupling mechanism for the nonlinear generation of shear flows in the presence of linearly unstable acoustic-gravity waves, possibly also leading to intermittency and chaos, is presented.
A programmable nonlinear acoustic metamaterial
Directory of Open Access Journals (Sweden)
Tianzhi Yang
2017-09-01
Full Text Available Acoustic metamaterials with specifically designed lattices can manipulate acoustic/elastic waves in unprecedented ways. Whereas there are many studies that focus on passive linear lattice, with non-reconfigurable structures. In this letter, we present the design, theory and experimental demonstration of an active nonlinear acoustic metamaterial, the dynamic properties of which can be modified instantaneously with reversibility. By incorporating active and nonlinear elements in a single unit cell, a real-time tunability and switchability of the band gap is achieved. In addition, we demonstrate a dynamic “editing” capability for shaping transmission spectra, which can be used to create the desired band gap and resonance. This feature is impossible to achieve in passive metamaterials. These advantages demonstrate the versatility of the proposed device, paving the way toward smart acoustic devices, such as logic elements, diode and transistor.
Oscillating nonlinear acoustic shock waves
DEFF Research Database (Denmark)
Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth
2016-01-01
We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show that at resona......We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....
Nonlinear positron acoustic solitary waves
International Nuclear Information System (INIS)
Tribeche, Mouloud; Aoutou, Kamel; Younsi, Smain; Amour, Rabia
2009-01-01
The problem of nonlinear positron acoustic solitary waves involving the dynamics of mobile cold positrons is addressed. A theoretical work is presented to show their existence and possible realization in a simple four-component plasma model. The results should be useful for the understanding of the localized structures that may occur in space and laboratory plasmas as new sources of cold positrons are now well developed.
Experimental verification of transient nonlinear acoustical holography.
Jing, Yun; Cannata, Jonathan; Wang, Tianren
2013-05-01
This paper presents an experimental study on nonlinear transient acoustical holography. The validity and effectiveness of a recently proposed nonlinear transient acoustical holography algorithm is evaluated in the presence of noise. The acoustic field measured on a post-focal plane of a high-intensity focused transducer is backward projected to reconstruct the pressure distributions on the focal and a pre-focal plane, which are shown to be in good agreement with the measurement. In contrast, the conventional linear holography produces erroneous results in this case where the nonlinearity involved is strong. Forward acoustic field projection was also carried out to further verify the algorithm.
Hidden acoustic information revealed by intentional nonlinearity
Dowling, David R.
2017-11-01
Acoustic waves are omnipresent in modern life and are well described by the linearized equations of fluid dynamics. Once generated, acoustic waves carry and collect information about their source and the environment through which they propagate, respectively, and this information may be retrieved by analyzing recordings of these waves. Because of this, acoustics is the primary means for observation, surveillance, reconnaissance, and remote sensing in otherwise opaque environments, such as the Earth's oceans and crust, and the interior of the human body. For such information-retrieval tasks, acoustic fields are nearly always interrogated within their recorded frequency range or bandwidth. However, this frequency-range restriction is not general; acoustic fields may also carry (hidden) information at frequencies outside their bandwidth. Although such a claim may seem counter intuitive, hidden acoustic-field information can be revealed by re-introducing a marquee trait of fluid dynamics: nonlinearity. In particular, an intentional quadratic nonlinearity - a form of intra-signal heterodyning - can be used to obtain acoustic field information at frequencies outside a recorded acoustic field's bandwidth. This quadratic nonlinearity enables a variety of acoustic remote sensing applications that were long thought to be impossible. In particular, it allows the detrimental effects of sparse recordings and random scattering to be suppressed when the original acoustic field has sufficient bandwidth. In this presentation, the topic is developed heuristically, with a just brief exposition of the relevant mathematics. Hidden acoustic field information is then revealed from simulated and measured acoustic fields in simple and complicated acoustic environments involving frequencies from a few Hertz to more than 100 kHz, and propagation distances from tens of centimeters to hundreds of kilometers. Sponsored by ONR, NAVSEA, and NSF.
Electron acoustic nonlinear structures in planetary magnetospheres
Shah, K. H.; Qureshi, M. N. S.; Masood, W.; Shah, H. A.
2018-04-01
In this paper, we have studied linear and nonlinear propagation of electron acoustic waves (EAWs) comprising cold and hot populations in which the ions form the neutralizing background. The hot electrons have been assumed to follow the generalized ( r , q ) distribution which has the advantage that it mimics most of the distribution functions observed in space plasmas. Interestingly, it has been found that unlike Maxwellian and kappa distributions, the electron acoustic waves admit not only rarefactive structures but also allow the formation of compressive solitary structures for generalized ( r , q ) distribution. It has been found that the flatness parameter r , tail parameter q , and the nonlinear propagation velocity u affect the propagation characteristics of nonlinear EAWs. Using the plasmas parameters, typically found in Saturn's magnetosphere and the Earth's auroral region, where two populations of electrons and electron acoustic solitary waves (EASWs) have been observed, we have given an estimate of the scale lengths over which these nonlinear waves are expected to form and how the size of these structures would vary with the change in the shape of the distribution function and with the change of the plasma parameters.
Nonlinear modulation of ion acoustic waves in a magnetized plasma
International Nuclear Information System (INIS)
Bharuthram, R.; Shukla, P.K.
1987-01-01
The quasistatic plasma slow response to coherent ion acoustic waves in a magnetized plasma is considered. A multidimensional cubic nonlinear Schroedinger equation is derived. It is found that the ion acoustic waves remain modulationally stable against oblique perturbations
Thermoviscous Model Equations in Nonlinear Acoustics
DEFF Research Database (Denmark)
Rasmussen, Anders Rønne
Four nonlinear acoustical wave equations that apply to both perfect gasses and arbitrary fluids with a quadratic equation of state are studied. Shock and rarefaction wave solutions to the equations are studied. In order to assess the accuracy of the wave equations, their solutions are compared...... to solutions of the basic equations from which the wave equations are derived. A straightforward weakly nonlinear equation is the most accurate for shock modeling. A higher order wave equation is the most accurate for modeling of smooth disturbances. Investigations of the linear stability properties...... of solutions to the wave equations, reveal that the solutions may become unstable. Such instabilities are not found in the basic equations. Interacting shocks and standing shocks are investigated....
Nonlinear acoustic waves in micro-inhomogeneous solids
Nazarov, Veniamin
2014-01-01
Nonlinear Acoustic Waves in Micro-inhomogeneous Solids covers the broad and dynamic branch of nonlinear acoustics, presenting a wide variety of different phenomena from both experimental and theoretical perspectives. The introductory chapters, written in the style of graduate-level textbook, present a review of the main achievements of classic nonlinear acoustics of homogeneous media. This enables readers to gain insight into nonlinear wave processes in homogeneous and micro-inhomogeneous solids and compare it within the framework of the book. The subsequent eight chapters covering: Physical m
Green function formalism for nonlinear acoustic waves in layered media
International Nuclear Information System (INIS)
Lobo, A.; Tsoy, E.; De Sterke, C.M.
2000-01-01
Full text: The applications of acoustic waves in identifying defects in adhesive bonds between metallic plates have received little attention at high intensities where the media respond nonlinearly. However, the effects of reduced bond strength are more distinct in the nonlinear response of the structure. Here we assume a weak nonlinearity acting as a small perturbation, thereby reducing the problem to a linear one. This enables us to develop a specialized Green function formalism for calculating acoustic fields in layered media
Nonlinear acoustics of water-saturated marine sediments
DEFF Research Database (Denmark)
Jensen, Leif Bjørnø
1976-01-01
Interest in the acoustic qualities of water-saturated marine sediments has increased considerably during recent years. The use of sources of high-intensity sound in oil propsecting, in geophysical and geological studies of bottom and subbottom materials and profiles and recently in marine...... archaeology has emphasized the need of information about the nonlinear acoustic qualities of water-saturated marine sediments. While the acoustic experiments and theoretical investigations hitherto performed have concentrated on a determination of the linear acoustic qualities of water-saturated marine...... sediments, their parameters of nonlinear acoustics are still unexplored. The strong absorption, increasing about linearly with frequency, found in most marine sediments and the occurrence of velocity dispersion by some marine sediments restrict the number of nonlinear acoustic test methods traditionally...
Non-Linear Excitation of Ion Acoustic Waves
DEFF Research Database (Denmark)
Michelsen, Poul; Hirsfield, J. L.
1974-01-01
The excitation of ion acoustic waves by nonlinear coupling of two transverse magnetic waves generated in a microwave cavity was investigated. Measurements of the wave amplitude showed good agreement with calculations based on the Vlasov equation.......The excitation of ion acoustic waves by nonlinear coupling of two transverse magnetic waves generated in a microwave cavity was investigated. Measurements of the wave amplitude showed good agreement with calculations based on the Vlasov equation....
Nonlinear characterization of a single-axis acoustic levitator
International Nuclear Information System (INIS)
Andrade, Marco A. B.; Ramos, Tiago S.; Okina, Fábio T. A.; Adamowski, Julio C.
2014-01-01
The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jump phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed
Nonlinear characterization of a single-axis acoustic levitator
Energy Technology Data Exchange (ETDEWEB)
Andrade, Marco A. B. [Institute of Physics, University of São Paulo, São Paulo (Brazil); Ramos, Tiago S.; Okina, Fábio T. A.; Adamowski, Julio C. [Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica, University of São Paulo, São Paulo (Brazil)
2014-04-15
The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jump phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed.
Nonlinear characterization of a single-axis acoustic levitator.
Andrade, Marco A B; Ramos, Tiago S; Okina, Fábio T A; Adamowski, Julio C
2014-04-01
The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jump phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed.
Effect of Forcing Function on Nonlinear Acoustic Standing Waves
Finkheiner, Joshua R.; Li, Xiao-Fan; Raman, Ganesh; Daniels, Chris; Steinetz, Bruce
2003-01-01
Nonlinear acoustic standing waves of high amplitude have been demonstrated by utilizing the effects of resonator shape to prevent the pressure waves from entering saturation. Experimentally, nonlinear acoustic standing waves have been generated by shaking an entire resonating cavity. While this promotes more efficient energy transfer than a piston-driven resonator, it also introduces complicated structural dynamics into the system. Experiments have shown that these dynamics result in resonator forcing functions comprised of a sum of several Fourier modes. However, previous numerical studies of the acoustics generated within the resonator assumed simple sinusoidal waves as the driving force. Using a previously developed numerical code, this paper demonstrates the effects of using a forcing function constructed with a series of harmonic sinusoidal waves on resonating cavities. From these results, a method will be demonstrated which allows the direct numerical analysis of experimentally generated nonlinear acoustic waves in resonators driven by harmonic forcing functions.
Nonlinear response and bistability of driven ion acoustic waves
Akbari-Moghanjoughi, M.
2017-08-01
The hydrodynamic model is used to obtain a generalized pseudoforce equation through which the nonlinear response of periodically driven ion acoustic waves is studied in an electron-ion plasma with isothermal and adiabatic ion fluids. The pseudotime series, corresponding to different driving frequencies, indicates that nonlinearity effects appear more strongly for smaller frequency values. The existence of extra harmonic resonances in the nonlinear amplitude spectrum is a clear indication of the interaction of an external force with harmonic components of the nonlinear ion acoustic waves. It is shown that many plasma parameters significantly and differently affect the nonlinear resonance spectrum of ion acoustic excitations. A heuristic but accurate model for the foldover effect is used which quite satisfactorily predicts the bistability of driven plasma oscillations. It is remarked that the characteristic resonance peak of isothermal ion plasma oscillations appears at lower frequencies but is stronger compared to that of adiabatic ions. Comparison of the exact numerical results for fully nonlinear and approximate (weakly nonlinear) models indicates that a weakly nonlinear model exaggerates the hysteresis and jump phenomenon for higher values of the external force amplitude.
Experimental observation of azimuthal shock waves on nonlinear acoustical vortices
International Nuclear Information System (INIS)
Brunet, Thomas; Thomas, Jean-Louis; Marchiano, Regis; Coulouvrat, Francois
2009-01-01
Thanks to a new focused array of piezoelectric transducers, experimental results are reported here to evidence helical acoustical shock waves resulting from the nonlinear propagation of acoustical vortices (AVs). These shock waves have a three-dimensional spiral shape, from which both the longitudinal and azimuthal components are studied. The inverse filter technique used to synthesize AVs allows various parameters to be varied, especially the topological charge which is the key parameter describing screw dislocations. Firstly, an analysis of the longitudinal modes in the frequency domain reveals a wide cascade of harmonics (up to the 60th order) leading to the formation of the shock waves. Then, an original measurement in the transverse plane exhibits azimuthal behaviour which has never been observed until now for acoustical shock waves. Finally, these new experimental results suggest interesting potential applications of nonlinear effects in terms of acoustics spanners in order to manipulate small objects.
Manipulating acoustic wave reflection by a nonlinear elastic metasurface
Guo, Xinxin; Gusev, Vitalyi E.; Bertoldi, Katia; Tournat, Vincent
2018-03-01
The acoustic wave reflection properties of a nonlinear elastic metasurface, derived from resonant nonlinear elastic elements, are theoretically and numerically studied. The metasurface is composed of a two degree-of-freedom mass-spring system with quadratic elastic nonlinearity. The possibility of converting, during the reflection process, most of the fundamental incoming wave energy into the second harmonic wave is shown, both theoretically and numerically, by means of a proper design of the nonlinear metasurface. The theoretical results from the harmonic balance method for a monochromatic source are compared with time domain simulations for a wave packet source. This protocol allows analyzing the dynamics of the nonlinear reflection process in the metasurface as well as exploring the limits of the operating frequency bandwidth. The reported methodology can be applied to a wide variety of nonlinear metasurfaces, thus possibly extending the family of exotic nonlinear reflection processes.
Nonlinear self-modulation of ion-acoustic waves
International Nuclear Information System (INIS)
Ikezi, H.; Schwarzenegger, K.; Simons, A.L.; Ohsawa, Y.; Kamimura, T.
1978-01-01
The nonlinear evolution of an ion-acoustic wave packet is studied. Experimentally, it is found that (i) nonlinear phase modulation develops in the wave packet; (ii) the phase modulation, together with the dispersion effect, causes expansion and breaking of the wave packet; (iii) the ions trapped in the troughs of the wave potential introduce self-phase modulation; and (iv) the ion-acoustic wave is stable with respect to the modulational instability. Computer simulations have reproduced the experimental results. The physical picture and the model equation describing the wave evolution are discussed
Gurbatov, S N; Saichev, A I
2012-01-01
"Waves and Structures in Nonlinear Nondispersive Media: General Theory and Applications to Nonlinear Acoustics” is devoted completely to nonlinear structures. The general theory is given here in parallel with mathematical models. Many concrete examples illustrate the general analysis of Part I. Part II is devoted to applications to nonlinear acoustics, including specific nonlinear models and exact solutions, physical mechanisms of nonlinearity, sawtooth-shaped wave propagation, self-action phenomena, nonlinear resonances and engineering application (medicine, nondestructive testing, geophysics, etc.). This book is designed for graduate and postgraduate students studying the theory of nonlinear waves of various physical nature. It may also be useful as a handbook for engineers and researchers who encounter the necessity of taking nonlinear wave effects into account of their work. Dr. Gurbatov S.N. is the head of Department, and Vice Rector for Research of Nizhny Novgorod State University. Dr. Rudenko O.V. is...
Nonlinear aspects of acoustic radiation force in biomedical applications
Energy Technology Data Exchange (ETDEWEB)
Ostrovsky, Lev, E-mail: Lev.A.Ostrovsky@noaa.gov [NOAA Earth System Research Laboratory, 325 Broadway, Boulder, Colorado 80305 (United States); Tsyuryupa, Sergey; Sarvazyan, Armen, E-mail: armen@artannlabs.com [Artann Laboratories, Inc., 1459 Lower Ferry Rd., West Trenton, New Jersey,08618 (United States)
2015-10-28
In the past decade acoustic radiation force (ARF) became a powerful tool in numerous biomedical applications. ARF from a focused ultrasound beam acts as a virtual “finger” for remote probing of internal anatomical structures and obtaining diagnostic information. This presentation deals with generation of shear waves by nonlinear focused beams. Albeit the ARF has intrinsically nonlinear origin, in most cases the primary ultrasonic wave was considered in the linear approximation. In this presentation, we consider the effects of nonlinearly distorted beams on generation of shear waves by such beams.
Nonlinear aspects of acoustic radiation force in biomedical applications
International Nuclear Information System (INIS)
Ostrovsky, Lev; Tsyuryupa, Sergey; Sarvazyan, Armen
2015-01-01
In the past decade acoustic radiation force (ARF) became a powerful tool in numerous biomedical applications. ARF from a focused ultrasound beam acts as a virtual “finger” for remote probing of internal anatomical structures and obtaining diagnostic information. This presentation deals with generation of shear waves by nonlinear focused beams. Albeit the ARF has intrinsically nonlinear origin, in most cases the primary ultrasonic wave was considered in the linear approximation. In this presentation, we consider the effects of nonlinearly distorted beams on generation of shear waves by such beams
Nonlinear aspects of acoustic radiation force in biomedical applications
Ostrovsky, Lev; Tsyuryupa, Sergey; Sarvazyan, Armen
2015-10-01
In the past decade acoustic radiation force (ARF) became a powerful tool in numerous biomedical applications. ARF from a focused ultrasound beam acts as a virtual "finger" for remote probing of internal anatomical structures and obtaining diagnostic information. This presentation deals with generation of shear waves by nonlinear focused beams. Albeit the ARF has intrinsically nonlinear origin, in most cases the primary ultrasonic wave was considered in the linear approximation. In this presentation, we consider the effects of nonlinearly distorted beams on generation of shear waves by such beams.
Nonlinearities and synchronization in musical acoustics and music psychology
Bader, Rolf
2013-01-01
Nonlinearities are a crucial and founding principle in nearly all musical systems, may they be musical instruments, timbre or rhythm perception and production, or neural networks of music perception. This volume gives an overview about present and past research in these fields. In Musical Acoustics, on the one hand the nonlinearities in musical instruments often produce the musically interesting features. On the other, musical instruments are nonlinear by nature, and tone production is the result of synchronization and self-organization within the instruments. Furthermore, as nearly all musical instruments are driven by impulses an Impulse Pattern Formulation (IPF) is suggested, an iterative framework holding for all musical instruments. It appears that this framework is able to reproduce the complex and perceptionally most salient initial transients of musical instruments. In Music Psychology, nonlinearities are present in all areas of musical features, like pitch, timbre, or rhythm perception. In terms of r...
PLASTIC PIPE DEFECT DETECTION USING NONLINEAR ACOUSTIC MODULATION
Directory of Open Access Journals (Sweden)
Gigih Priyandoko
2015-02-01
Full Text Available This project discuss about the defect detection of plastic pipe by using nonlinear acoustic wave modulation method. Nonlinaer acoustic modulations are investigated for fatigue crack detection. It is a sensitive method for damage detection and it is based on the propagation of high frequency acoustic waves in plastic pipe with low frequency excitation. The plastic pipe is excited simultaneously with a slow amplitude modulated vibration pumping wave and a constant amplitude probing wave. The frequency of both the excitation signals coincides with the resonances of the plastic pipe. An actuator is used for frequencies generation while sensor is used for the frequencies detection. Besides that, a PVP pipe is used as the specimen as it is commonly used for the conveyance of liquid in many fields. The results obtained are being observed and the difference between uncrack specimen and cracked specimen can be distinguished.
Khokhlov Zabolotskaya Kuznetsov type equation: nonlinear acoustics in heterogeneous media
Kostin, Ilya; Panasenko, Grigory
2006-04-01
The KZK type equation introduced in this Note differs from the traditional form of the KZK model known in acoustics by the assumptions on the nonlinear term. For this modified form, a global existence and uniqueness result is established for the case of non-constant coefficients. Afterwards the asymptotic behaviour of the solution of the KZK type equation with rapidly oscillating coefficients is studied. To cite this article: I. Kostin, G. Panasenko, C. R. Mecanique 334 (2006).
Dynamics of metastable breathers in nonlinear chains in acoustic vacuum
Sen, Surajit; Mohan, T. R. Krishna
2009-03-01
The study of the dynamics of one-dimensional chains with both harmonic and nonlinear interactions, as in the Fermi-Pasta-Ulam and related problems, has played a central role in efforts to identify the broad consequences of nonlinearity in these systems. Nevertheless, little is known about the dynamical behavior of purely nonlinear chains where there is a complete absence of the harmonic term, and hence sound propagation is not admissible, i.e., under conditions of “acoustic vacuum.” Here we study the dynamics of highly localized excitations, or breathers, which are known to be initiated by the quasistatic stretching of the bonds between adjacent particles. We show via detailed particle-dynamics-based studies that many low-energy pulses also form in the vicinity of the perturbation, and the breathers that form are “fragile” in the sense that they can be easily delocalized by scattering events in the system. We show that the localized excitations eventually disperse, allowing the system to attain an equilibrium-like state that is realizable in acoustic vacuum. We conclude with a discussion of how the dynamics is affected by the presence of acoustic oscillations.
Free-vibration acoustic resonance of a nonlinear elastic bar
Tarumi, Ryuichi; Oshita, Yoshihito
2011-02-01
Free-vibration acoustic resonance of a one-dimensional nonlinear elastic bar was investigated by direct analysis in the calculus of variations. The Lagrangian density of the bar includes a cubic term of the deformation gradient, which is responsible for both geometric and constitutive nonlinearities. By expanding the deformation function into a complex Fourier series, we derived the action integral in an analytic form and evaluated its stationary conditions numerically with the Ritz method for the first three resonant vibration modes. This revealed that the bar shows the following prominent nonlinear features: (i) amplitude dependence of the resonance frequency; (ii) symmetry breaking in the vibration pattern; and (iii) excitation of the high-frequency mode around nodal-like points. Stability of the resonant vibrations was also addressed in terms of a convex condition on the strain energy density.
Theory of nonlinear acoustic forces acting on fluids and particles in microsystems
DEFF Research Database (Denmark)
Karlsen, Jonas Tobias
fundamentally new capabilities in chemical, biomedical, or clinical studies of single cells and bioparticles. This thesis, entitled Theory of nonlinear acoustic forces acting on fluids and particles in microsystems, advances the fundamental understanding of acoustofluidics by addressing the origin...... of the nonlinear acoustic forces acting on fluids and particles. Classical results in nonlinear acoustics for the non-dissipative acoustic radiation force acting on a particle or an interface, as well as the dissipative acoustic force densities driving acoustic streaming, are derived and discussed in terms...... in the continuous fluid parameters of density and compressibility, e.g., due to a solute concentration field, the thesis presents novel analytical results on the acoustic force density acting on inhomogeneous fluids in acoustic fields. This inhomogeneity-induced acoustic force density is non-dissipative in origin...
Acoustic nonlinear periodic waves in pair-ion plasmas
Mahmood, Shahzad; Kaladze, Tamaz; Ur-Rehman, Hafeez
2013-09-01
Electrostatic acoustic nonlinear periodic (cnoidal) waves and solitons are investigated in unmagnetized pair-ion plasmas consisting of same mass and oppositely charged ion species with different temperatures. Using reductive perturbation method and appropriate boundary conditions, the Korteweg-de Vries (KdV) equation is derived. The analytical solutions of both cnoidal wave and soliton solutions are discussed in detail. The phase plane plots of cnoidal and soliton structures are shown. It is found that both compressive and rarefactive cnoidal wave and soliton structures are formed depending on the temperature ratio of positive and negative ions in pair-ion plasmas. In the special case, it is revealed that the amplitude of soliton may become larger than it is allowed by the nonlinear stationary wave theory which is equal to the quantum tunneling by particle through a potential barrier effect. The serious flaws in the earlier published results by Yadav et al., [PRE 52, 3045 (1995)] and Chawla and Misra [Phys. Plasmas 17, 102315 (2010)] of studying ion acoustic nonlinear periodic waves are also pointed out.
Multi-crack imaging using nonclassical nonlinear acoustic method
International Nuclear Information System (INIS)
Zhang Lue; Zhang Ying; Liu Xiao-Zhou; Gong Xiu-Fen
2014-01-01
Solid materials with cracks exhibit the nonclassical nonlinear acoustical behavior. The micro-defects in solid materials can be detected by nonlinear elastic wave spectroscopy (NEWS) method with a time-reversal (TR) mirror. While defects lie in viscoelastic solid material with different distances from one another, the nonlinear and hysteretic stress—strain relation is established with Preisach—Mayergoyz (PM) model in crack zone. Pulse inversion (PI) and TR methods are used in numerical simulation and defect locations can be determined from images obtained by the maximum value. Since false-positive defects might appear and degrade the imaging when the defects are located quite closely, the maximum value imaging with a time window is introduced to analyze how defects affect each other and how the fake one occurs. Furthermore, NEWS-TR-NEWS method is put forward to improve NEWS-TR scheme, with another forward propagation (NEWS) added to the existing phases (NEWS and TR). In the added phase, scanner locations are determined by locations of all defects imaged in previous phases, so that whether an imaged defect is real can be deduced. NEWS-TR-NEWS method is proved to be effective to distinguish real defects from the false-positive ones. Moreover, it is also helpful to detect the crack that is weaker than others during imaging procedure. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Quantum corrections to nonlinear ion acoustic wave with Landau damping
Energy Technology Data Exchange (ETDEWEB)
Mukherjee, Abhik; Janaki, M. S. [Saha Institute of Nuclear Physics, Calcutta (India); Bose, Anirban [Serampore College, West Bengal (India)
2014-07-15
Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to the presence of Landau damping terms has been calculated assuming the Landau damping parameter α{sub 1}=√(m{sub e}/m{sub i}) to be of the same order of the quantum parameter Q=ℏ{sup 2}/(24m{sup 2}c{sub s}{sup 2}L{sup 2}). The amplitude is shown to decay very slowly with time as determined by the quantum factor Q.
Nonlinear acoustic waves in partially ionized collisional plasmas
International Nuclear Information System (INIS)
Rao, N.N.; Kaup, D.J.; Shukla, P.K.
1991-01-01
Nonlinear propagation of acoustic-type waves in a partially ionized three-component collisional plasma consisting of electrons, ions and neutral particles is investigated. For bidirectional propagation, it is shown that the small- but finite-amplitude waves are governed by the Boussinesq equation, which for unidirectional propagation near the acoustic speed reduces to the usual Korteweg-de Vries equation. For large-amplitude waves, it is demonstrated that the relevant fluid equations are integrable in a stationary frame, and the parameter values for the existence of finite-amplitude solutions are explicitly obtained. In both cases, the different temperatures of the individual species, are taken into account. The relevance of the results to the earth's ionospheric plasma in the lower altitude ranges is pointed out. (author)
Long-Term Aging Diagnosis of Rotor Steel Using Acoustic Nonlinearity
Energy Technology Data Exchange (ETDEWEB)
Kim, Chung Seok; Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of); Park, Ik Keun; Hyun, Chang Yong [Seoul National University of Science and Tecnology, Seoul (Korea, Republic of)
2011-12-15
The long-term aging of ferritic 2.25CrMo steel was characterized using the acoustic nonlinear effect in order to apply to diagnose the degradation behavior of structural materials. We measured the acoustic nonlinearity parameter for each thermally aged specimen by the higher harmonic-generation technique. The acoustic nonlinearity parameter increased with aging time due to equilibrium M6C carbide precipitation, and has a favorable linear relation with Rockwell hardness. This study suggests that acoustic nonlinearity testing may be applicable to diagnostics on strength degradation in rotor steels.
Nonlinear Acoustic and Ultrasonic NDT of Aeronautical Components
Van Den Abeele, Koen; Katkowski, Tomasz; Mattei, Christophe
2006-05-01
In response to the demand for innovative microdamage inspection systems, with high sensitivity and undoubted accuracy, we are currently investigating the use and robustness of several acoustic and ultrasonic NDT techniques based on Nonlinear Elastic Wave Spectroscopy (NEWS) for the characterization of microdamage in aeronautical components. In this report, we illustrate the results of an amplitude dependent analysis of the resonance behaviour, both in time (signal reverberation) and in frequency (sweep) domain. The technique is applied to intact and damaged samples of Carbon Fiber Reinforced Plastics (CFRP) composites after thermal loading or mechanical fatigue. The method shows a considerable gain in sensitivity and an incontestable interpretation of the results for nonlinear signatures in comparison with the linear characteristics. For highly fatigued samples, slow dynamical effects are observed.
Gusev, Vitalyi E; Ni, Chenyin; Lomonosov, Alexey; Shen, Zhonghua
2015-08-01
Theory accounting for the influence of hysteretic nonlinearity of micro-inhomogeneous material on flexural wave in the plates of continuously varying thickness is developed. For the wedges with thickness increasing as a power law of distance from its edge strong modifications of the wave dynamics with propagation distance are predicted. It is found that nonlinear absorption progressively disappearing with diminishing wave amplitude leads to complete attenuation of acoustic waves in most of the wedges exhibiting black hole phenomenon. It is also demonstrated that black holes exist beyond the geometrical acoustic approximation. Applications include nondestructive evaluation of micro-inhomogeneous materials and vibrations damping. Copyright © 2015 Elsevier B.V. All rights reserved.
Computer simulations on the nonlinear frequency shift and nonlinear modulation of ion-acoustic waves
International Nuclear Information System (INIS)
Ohsawa, Yukiharu; Kamimura, Tetsuo.
1976-11-01
The nonlinear behavior of ion-acoustic waves with rather short wave-length, k lambda sub(De) asymptotically equals 1, is investigated by computer sumulations. It is observed that the nonlinear frequency shift is negative and is proportional to square root of the initial wave amplitude when the amplitude is not too large. This proportionality breaks down and the frequency shift can become positive (for large Te/Ti), when (n tilde sub(i)/n 0 )sup(1/2)>0.25, where n tilde sub(i) is the ion density perturbation and n 0 the average plasma density. Nonlinear modulation of the wave-packet is clearly seen; however, modulational instability was not observed. The importance of the effects of trapped ions to these phenomena is emphasized. (auth.)
Measurement of the Acoustic Nonlinearity Parameter for Biological Media.
Cobb, Wesley Nelson
In vitro measurements of the acoustic nonlinearity parameter are presented for several biological media. With these measurements it is possible to predict the distortion of a finite amplitude wave in biological tissues of current diagnostic and research interest. The measurement method is based on the finite amplitude distortion of a sine wave that is emmitted by a piston source. The growth of the second harmonic component of this wave is measured by a piston receiver which is coaxial with and has the same size as the source. The experimental measurements and theory are compared in order to determine the nonlinearity parameter. The density, sound speed, and attenuation for the medium are determined in order to make this comparison. The theory developed for this study accounts for the influence of both diffraction and attenuation on the experimental measurements. The effects of dispersion, tissue inhomogeneity and gas bubbles within the excised tissues are studied. To test the measurement method, experimental results are compared with established values for the nonlinearity parameter of distilled water, ethylene glycol and glycerol. The agreement between these values suggests that the measurement uncertainty is (+OR-) 5% for liquids and (+OR-) 10% for solid tissues. Measurements are presented for dog blood and bovine serum albumen as a function of concentration. The nonlinearity parameters for liver, kidney and spleen are reported for both human and canine tissues. The values for the fresh tissues displayed little variation (6.8 to 7.8). Measurements for fixed, normal and cirrhotic tissues indicated that the nonlinearity parameter does not depend strongly on pathology. However, the values for fixed tissues were somewhat higher than those of the fresh tissues.
Nonlinear acoustic properties of the B95 aluminum alloy and the B95/nanodiamond composite
Korobov, A. I.; Prokhorov, V. M.
2016-11-01
Research results for the nonlinear acoustic properties of the B95 polycrystalline aluminum alloy and the B95/nanodiamond composite have been described. The nonlinear properties of the alloys have been studied by the spectral method that measures the efficiency of generation of the second harmonic of a bulk acoustic wave at a frequency of 2 f = 10 MHz in the field of a finite-amplitude longitudinal acoustic wave at a frequency of f = 5 MHz. The results derived by this method have been compared with the results of studies of the nonlinear acoustic properties of the test alloys using the Thurston-Brugger quasi-static method.
Multi-crack imaging using nonclassical nonlinear acoustic method
Zhang, Lue; Zhang, Ying; Liu, Xiao-Zhou; Gong, Xiu-Fen
2014-10-01
Solid materials with cracks exhibit the nonclassical nonlinear acoustical behavior. The micro-defects in solid materials can be detected by nonlinear elastic wave spectroscopy (NEWS) method with a time-reversal (TR) mirror. While defects lie in viscoelastic solid material with different distances from one another, the nonlinear and hysteretic stress—strain relation is established with Preisach—Mayergoyz (PM) model in crack zone. Pulse inversion (PI) and TR methods are used in numerical simulation and defect locations can be determined from images obtained by the maximum value. Since false-positive defects might appear and degrade the imaging when the defects are located quite closely, the maximum value imaging with a time window is introduced to analyze how defects affect each other and how the fake one occurs. Furthermore, NEWS-TR-NEWS method is put forward to improve NEWS-TR scheme, with another forward propagation (NEWS) added to the existing phases (NEWS and TR). In the added phase, scanner locations are determined by locations of all defects imaged in previous phases, so that whether an imaged defect is real can be deduced. NEWS-TR-NEWS method is proved to be effective to distinguish real defects from the false-positive ones. Moreover, it is also helpful to detect the crack that is weaker than others during imaging procedure.
Nonlinear acoustics determination of phase characteristics of PVDF membrane hydrophones
International Nuclear Information System (INIS)
Bloomfield, Philip E; Lewin, Peter A; Gandhi, Gaurav
2011-01-01
When an ultrasonic pressure wave propagates through a nonlinear medium, the relative phasing of the generated harmonics causes a distinct asymmetry between the positive and negative pressure levels and between the rise and fall time of examined waveforms. A faithful quantitative reproduction of the source transducer's pressure field requires amplitude and phase measurements by calibrated hydrophone probes. Nonlinear hydrophone calibration provides amplitude and phase information at discrete multiples of an acoustic source's fundamental frequency. Two PVDF bilaminar membrane hydrophones were first calibrated in terms of their amplitude sensitivity to the pressure levels generated by two different HIFU (High Intensity Focused Ultrasound) circular source transducers operating at 5 MHz and 10 MHz, enabling phase studies up to 105 and 100 MHz, respectively. Introducing two newly-developed phase-dispersion representations, the phase responses of the two membrane hydrophones were determined with respect to the phase of the complex frequency response extracted from the nonlinear field simulated by a semi-empirical computer model which predicts the near and the far field pressure distributions. These phase differences compared favorably with the results obtained from the commercially available PiezoCAD simulation model. The protocol for specifying the complex pressure field of source transducers through measurements using the calibrated hydrophones is described. The results obtained indicate that the membranes exhibit close to linear decay of phase against the frequency.
Nonlinear acoustics determination of phase characteristics of PVDF membrane hydrophones
Energy Technology Data Exchange (ETDEWEB)
Bloomfield, Philip E; Lewin, Peter A; Gandhi, Gaurav, E-mail: bloomfpe@drexel.edu [Drexel University School of Biomedical Engineering, Science, and Health Systems, Philadelphia, PA 19104-2875 (United States)
2011-02-01
When an ultrasonic pressure wave propagates through a nonlinear medium, the relative phasing of the generated harmonics causes a distinct asymmetry between the positive and negative pressure levels and between the rise and fall time of examined waveforms. A faithful quantitative reproduction of the source transducer's pressure field requires amplitude and phase measurements by calibrated hydrophone probes. Nonlinear hydrophone calibration provides amplitude and phase information at discrete multiples of an acoustic source's fundamental frequency. Two PVDF bilaminar membrane hydrophones were first calibrated in terms of their amplitude sensitivity to the pressure levels generated by two different HIFU (High Intensity Focused Ultrasound) circular source transducers operating at 5 MHz and 10 MHz, enabling phase studies up to 105 and 100 MHz, respectively. Introducing two newly-developed phase-dispersion representations, the phase responses of the two membrane hydrophones were determined with respect to the phase of the complex frequency response extracted from the nonlinear field simulated by a semi-empirical computer model which predicts the near and the far field pressure distributions. These phase differences compared favorably with the results obtained from the commercially available PiezoCAD simulation model. The protocol for specifying the complex pressure field of source transducers through measurements using the calibrated hydrophones is described. The results obtained indicate that the membranes exhibit close to linear decay of phase against the frequency.
Nonlinear acoustics determination of phase characteristics of PVDF membrane hydrophones
Bloomfield, Philip E.; Gandhi, Gaurav; Lewin, Peter A.
2011-02-01
When an ultrasonic pressure wave propagates through a nonlinear medium, the relative phasing of the generated harmonics causes a distinct asymmetry between the positive and negative pressure levels and between the rise and fall time of examined waveforms. A faithful quantitative reproduction of the source transducer's pressure field requires amplitude and phase measurements by calibrated hydrophone probes. Nonlinear hydrophone calibration provides amplitude and phase information at discrete multiples of an acoustic source's fundamental frequency. Two PVDF bilaminar membrane hydrophones were first calibrated in terms of their amplitude sensitivity to the pressure levels generated by two different HIFU (High Intensity Focused Ultrasound) circular source transducers operating at 5 MHz and 10 MHz, enabling phase studies up to 105 and 100 MHz, respectively. Introducing two newly-developed phase-dispersion representations, the phase responses of the two membrane hydrophones were determined with respect to the phase of the complex frequency response extracted from the nonlinear field simulated by a semi-empirical computer model which predicts the near and the far field pressure distributions. These phase differences compared favorably with the results obtained from the commercially available PiezoCAD simulation model. The protocol for specifying the complex pressure field of source transducers through measurements using the calibrated hydrophones is described. The results obtained indicate that the membranes exhibit close to linear decay of phase against the frequency.
Impact of nonlinear distortion on acoustic radiation force elastography.
Draudt, Andrew B; Cleveland, Robin O
2011-11-01
High-intensity focused ultrasound (HIFU) produces an acoustic radiation force that induces tissue displacement, which can be measured by monitoring time shifts in the backscattered signals from interrogation pulses. If the pulse occurs simultaneously with the HIFU, the arrival time of the backscatter will be biased because nonlinearity associated with the HIFU changes the local sound speed. Measurements of the pressure field using 1.1 MHz HIFU and a 7.5 MHz pulse in water exhibited a nonlinearly induced apparent displacement (NIAD) that varied with the HIFU pressure, propagation distance and the timing of the pulse relative to the HIFU. Nonlinear simulations employing the KZK equation predicted NIADs that agreed with measurements. Experiments with chicken breast demonstrated a NIAD with magnitude similar to that expected from the radiation force. Finally it was shown that if two pulses were fired with different phases relative to the HIFU, then upon averaging, the NIAD could be mitigated. Copyright © 2011 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
Layer contributions to the nonlinear acoustic radiation from stratified media.
Vander Meulen, François; Haumesser, Lionel
2016-12-01
This study presents the thorough investigation of the second harmonic generation scenario in a three fluid layer system. An emphasis is on the evaluation of the nonlinear parameter B/A in each layer from remote measurements. A theoretical approach of the propagation of a finite amplitude acoustic wave in a multilayered medium is developed. In the frame of the KZK equation, the weak nonlinearity of the media, attenuation and diffraction effects are computed for the fundamental and second harmonic waves propagating back and forth in each of the layers of the system. The model uses a gaussian expansion to describe the beam propagation in order to quantitatively evaluate the contribution of each part of the system (layers and interfaces) to its nonlinearity. The model is validated through measurements on a water/aluminum/water system. Transmission as well as reflection configurations are studied. Good agreement is found between the theoretical results and the experimental data. The analysis of the second harmonic field sources measured by the transducers from outside the stratified medium highlights the factors that favor the cumulative effects. Copyright © 2016 Elsevier B.V. All rights reserved.
Nonlinear ion-acoustic waves and solitons in a magnetized plasma
International Nuclear Information System (INIS)
Lee, L.C.; Kan, J.R.
1981-01-01
A unified formulation is presented to study the nonlinear low-frequency electrostatic waves in a magnetized low-β plasma. It is found that there exist three types of nonlinear waves; (1) nonlinear ion-cyclotron periodic waves with a wave speed V/sub p/ > C/sub s/ (ion-acoustic velocity); (2) nonlinear ion-acoustic periodic waves with V/sub p/ < C/sub s/ costheta; and (3) ion-acoustic solitons with C/sub s/ costheta < V/sub p/ < C/sub s/, where theta is the angle between the wave vector and the magnetic field
Nonlinear excitation of geodesic acoustic modes by drift waves
International Nuclear Information System (INIS)
Chakrabarti, N.; Singh, R.; Kaw, P. K.; Guzdar, P. N.
2007-01-01
In this paper, two mode-coupling analyses for the nonlinear excitation of the geodesic acoustic modes (GAMs) in tokamak plasmas by drift waves are presented. The first approach is a coherent parametric process, which leads to a three-wave resonant interaction. This investigation allows for the drift waves and the GAMs to have comparable scales. The second approach uses the wave-kinetic equations for the drift waves, which then couples to the GAMs. This requires that the GAM scale length be large compared to the wave packet associated with the drift waves. The resonance conditions for these two cases lead to specific predictions of the radial wave number of the excited GAMs
Nonlinear effects of dark energy clustering beyond the acoustic scales
International Nuclear Information System (INIS)
Anselmi, Stefano; Nacir, Diana López; Sefusatti, Emiliano
2014-01-01
We extend the resummation method of Anselmi and Pietroni (2012) to compute the total density power spectrum in models of quintessence characterized by a vanishing speed of sound. For standard ΛCDM cosmologies, this resummation scheme allows predictions with an accuracy at the few percent level beyond the range of scales where acoustic oscillations are present, therefore comparable to other, common numerical tools. In addition, our theoretical approach indicates an approximate but valuable and simple relation between the power spectra for standard quintessence models and models where scalar field perturbations appear at all scales. This, in turn, provides an educated guess for the prediction of nonlinear growth in models with generic speed of sound, particularly valuable since no numerical results are yet available
Nonlinear effects of dark energy clustering beyond the acoustic scales
Energy Technology Data Exchange (ETDEWEB)
Anselmi, Stefano [Department of Physics/CERCA/ISO, Case Western Reserve University, Cleveland, OH 44106-7079 (United States); Nacir, Diana López [The Abdus Salam International Center for Theoretical Physics, Strada costiera 11, I-34151 Trieste (Italy); Sefusatti, Emiliano, E-mail: stefano.anselmi@case.edu, E-mail: dlopez_n@ictp.it, E-mail: emiliano.sefusatti@brera.inaf.it [INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Saint Lucia) (Italy)
2014-07-01
We extend the resummation method of Anselmi and Pietroni (2012) to compute the total density power spectrum in models of quintessence characterized by a vanishing speed of sound. For standard ΛCDM cosmologies, this resummation scheme allows predictions with an accuracy at the few percent level beyond the range of scales where acoustic oscillations are present, therefore comparable to other, common numerical tools. In addition, our theoretical approach indicates an approximate but valuable and simple relation between the power spectra for standard quintessence models and models where scalar field perturbations appear at all scales. This, in turn, provides an educated guess for the prediction of nonlinear growth in models with generic speed of sound, particularly valuable since no numerical results are yet available.
International Nuclear Information System (INIS)
Yi Sumin; Ryu, C.-M.; Yoon, Peter H.
2003-01-01
The nonlinear frequency shift of a low-frequency, coherent dust-acoustic wave in the presence of higher frequency dust-acoustic turbulence is investigated in the framework of weak turbulence theory. It is found that the frequency shift of the dust-acoustic wave in an unmagnetized dusty plasma is always positive irrespective of the propagation direction of the coherent wave. It is also found that turbulent waves propagating in the same direction as the coherent wave are shown to give rise to a much higher frequency shift than the opposite case. Finally, it is shown that the nonlinear frequency shift of a dust-acoustic wave is more pronounced than in the case of the customary ion-acoustic waves in fully ionized plasmas
Actuation of atomic force microscopy microcantilevers using contact acoustic nonlinearities
Energy Technology Data Exchange (ETDEWEB)
Torello, D.; Degertekin, F. Levent, E-mail: levent.degertekin@me.gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)
2013-11-15
A new method of actuating atomic force microscopy (AFM) cantilevers is proposed in which a high frequency (>5 MHz) wave modulated by a lower frequency (∼300 kHz) wave passes through a contact acoustic nonlinearity at the contact interface between the actuator and the cantilever chip. The nonlinearity converts the high frequency, modulated signal to a low frequency drive signal suitable for actuation of tapping-mode AFM probes. The higher harmonic content of this signal is filtered out mechanically by the cantilever transfer function, providing for clean output. A custom probe holder was designed and constructed using rapid prototyping technologies and off-the-shelf components and was interfaced with an Asylum Research MFP-3D AFM, which was then used to evaluate the performance characteristics with respect to standard hardware and linear actuation techniques. Using a carrier frequency of 14.19 MHz, it was observed that the cantilever output was cleaner with this actuation technique and added no significant noise to the system. This setup, without any optimization, was determined to have an actuation bandwidth on the order of 10 MHz, suitable for high speed imaging applications. Using this method, an image was taken that demonstrates the viability of the technique and is compared favorably to images taken with a standard AFM setup.
A new type of surface acoustic waves in solids due to nonlinear elasticity
International Nuclear Information System (INIS)
Mozhaev, V.G.
1988-12-01
It is shown that in nonlinear elastic semi-infinite medium possessing a property of self focusing of shear waves, besides bulk non-linear shear waves, new surface acoustic waves exist, localization of which near the boundary is entirely due to nonlinear effects. (author). 8 refs
International Nuclear Information System (INIS)
Yu-Lin, Feng; Xiao-Zhou, Liu; Jie-Hui, Liu; Li, Ma
2009-01-01
Based on an equivalent medium approach, this paper presents a model describing the nonlinear propagation of acoustic waves in a viscoelastic medium containing cylindrical micropores. The influences of pores' nonlinear oscillations on sound attenuation, sound dispersion and an equivalent acoustic nonlinearity parameter are discussed. The calculated results show that the attenuation increases with an increasing volume fraction of micropores. The peak of sound velocity and attenuation occurs at the resonant frequency of the micropores while the peak of the equivalent acoustic nonlinearity parameter occurs at the half of the resonant frequency of the micropores. Furthermore, multiple scattering has been taken into account, which leads to a modification to the effective wave number in the equivalent medium approach. We find that these linear and nonlinear acoustic parameters need to be corrected when the volume fraction of micropores is larger than 0.1%
Collisionless damping of nonlinear dust ion acoustic wave due to dust charge fluctuation
International Nuclear Information System (INIS)
Ghosh, Samiran; Chaudhuri, Tushar K.; Sarkar, Susmita; Khan, Manoranjan; Gupta, M.R.
2002-01-01
A dissipation mechanism for the damping of the nonlinear dust ion acoustic wave in a collisionless dusty plasma consisting of nonthermal electrons, ions, and variable charge dust grains has been investigated. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust ion acoustic wave propagation to be described by the damped Korteweg-de Vries equation. Due to the presence of nonthermal electrons, the dust ion acoustic wave admits both positive and negative potential and it suffers less damping than the dust acoustic wave, which admits only negative potential
Nonlinear Time Reversal Acoustic Method of Friction Stir Weld Assessment, Phase I
National Aeronautics and Space Administration — The goal of the project is demonstration of the feasibility of Friction Stir Weld (FSW) assessment by novel Nonlinear Time Reversal Acoustic (TRA) method. Time...
Time reversal invariance for a nonlinear scatterer exhibiting contact acoustic nonlinearity
Blanloeuil, Philippe; Rose, L. R. Francis; Veidt, Martin; Wang, Chun H.
2018-03-01
The time reversal invariance of an ultrasonic plane wave interacting with a contact interface characterized by a unilateral contact law is investigated analytically and numerically. It is shown analytically that despite the contact nonlinearity, the re-emission of a time reversed version of the reflected and transmitted waves can perfectly recover the original pulse shape, thereby demonstrating time reversal invariance for this type of contact acoustic nonlinearity. With the aid of finite element modelling, the time-reversal analysis is extended to finite-size nonlinear scatterers such as closed cracks. The results show that time reversal invariance holds provided that all the additional frequencies generated during the forward propagation, such as higher harmonics, sub-harmonics and zero-frequency component, are fully included in the retro-propagation. If the scattered waves are frequency filtered during receiving or transmitting, such as through the use of narrowband transducers, the recombination of the time-reversed waves will not exactly recover the original incident wave. This discrepancy due to incomplete time invariance can be exploited as a new method for characterizing damage by defining damage indices that quantify the departure from time reversal invariance. The sensitivity of these damage indices for various crack lengths and contact stress levels is investigated computationally, indicating some advantages of this narrowband approach relative to the more conventional measurement of higher harmonic amplitude, which requires broadband transducers.
Acoustic wave focusing in complex media using Nonlinear Time Reversal coded signal processing
Czech Academy of Sciences Publication Activity Database
Dos Santos, S.; Dvořáková, Zuzana; Lints, M.; Kůs, V.; Salupere, A.; Převorovský, Zdeněk
2014-01-01
Roč. 19, č. 12 (2014) ISSN 1435-4934. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. Praha, 06.10.2014-10.10.2014] Institutional support: RVO:61388998 Keywords : ultrasonic testing (UT) * signal processing * TR- NEWS * nonlinear time reversal * NDT * nonlinear acoustics Subject RIV: BI - Acoustics http://www.ndt.net/events/ECNDT2014/app/content/Slides/590_DosSantos_Rev1.pdf
Nonlinear Electron Acoustic Waves in Dissipative Plasma with Superthermal Electrons
El-Hanbaly, A. M.; El-Shewy, E. K.; Kassem, A. I.; Darweesh, H. F.
2016-01-01
The nonlinear properties of small amplitude electron-acoustic ( EA) solitary and shock waves in a homogeneous system of unmagnetized collisionless plasma consisted of a cold electron fluid and superthermal hot electrons obeying superthermal distribution, and stationary ions have been investigated. A reductive perturbation method was employed to obtain the Kadomstev-Petviashvili-Burgers (KP-Brugers) equation. Some solutions of physical interest are obtained. These solutions are related to soliton, monotonic and oscillatory shock waves and their behaviour are shown graphically. The formation of these solutions depends crucially on the value of the Burgers term and the plasma parameters as well. By using the tangent hyperbolic (tanh) method, another interesting type of solution which is a combination between shock and soliton waves is obtained. The topology of phase portrait and potential diagram of the KP-Brugers equation is investigated.The advantage of using this method is that one can predict different classes of the travelling wave solutions according to different phase orbits. The obtained results may be helpful in better understanding of waves propagation in various space plasma environments as well as in inertial confinement fusion laboratory plasmas.
Nonlinear ion-acoustic cnoidal waves in a dense relativistic degenerate magnetoplasma.
El-Shamy, E F
2015-03-01
The complex pattern and propagation characteristics of nonlinear periodic ion-acoustic waves, namely, ion-acoustic cnoidal waves, in a dense relativistic degenerate magnetoplasma consisting of relativistic degenerate electrons and nondegenerate cold ions are investigated. By means of the reductive perturbation method and appropriate boundary conditions for nonlinear periodic waves, a nonlinear modified Korteweg-de Vries (KdV) equation is derived and its cnoidal wave is analyzed. The various solutions of nonlinear ion-acoustic cnoidal and solitary waves are presented numerically with the Sagdeev potential approach. The analytical solution and numerical simulation of nonlinear ion-acoustic cnoidal waves of the nonlinear modified KdV equation are studied. Clearly, it is found that the features (amplitude and width) of nonlinear ion-acoustic cnoidal waves are proportional to plasma number density, ion cyclotron frequency, and direction cosines. The numerical results are applied to high density astrophysical situations, such as in superdense white dwarfs. This research will be helpful in understanding the properties of compact astrophysical objects containing cold ions with relativistic degenerate electrons.
Precipitate Contribution to the Acoustic Nonlinearity in Nickel-Based Superalloy
Institute of Scientific and Technical Information of China (English)
Chung-Seok KIM; Cliff J.LISSENDEN
2009-01-01
The influence of γ' precipitate on the acoustic nonlinearity is investigated for a nickel-based superalloy,which is subjected to creep deformation.During creep deformation,the cuboidal γ' precipitate is preferentially coarsened in a direction perpendicular to the applied stress axis.The length and shape factor of the γ' precipitate increase with creep time.The increase of relative acoustic nonlinearity with increasing fraction of creep life is discussed in relation to the rafting of γ' precipitate,which is closely related to the scattering and distortion of the acoustic wave.
A new theoretical basis for numerical simulations of nonlinear acoustic fields
Wójcik, Janusz
2000-07-01
Nonlinear acoustic equations can be considerably simplified. The presented model retains the accuracy of a more complex description of nonlinearity and a uniform description of near and far fields (in contrast to the KZK equation). A method has been presented for obtaining solutions of Kuznetsov's equation from the solutions of the model under consideration. Results of numerical calculations, including comparative ones, are presented.
Fan, Tingbo; Liu, Zhenbo; Chen, Tao; Li, Faqi; Zhang, Dong
2011-09-01
In this work, the authors propose a modeling approach to compute the nonlinear acoustic field generated by a flat piston transmitter with an attached aluminum lens. In this approach, the geometrical parameters (radius and focal length) of a virtual source are initially determined by Snell's refraction law and then adjusted based on the Rayleigh integral result in the linear case. Then, this virtual source is used with the nonlinear spheroidal beam equation (SBE) model to predict the nonlinear acoustic field in the focal region. To examine the validity of this approach, the calculated nonlinear result is compared with those from the Westervelt and (Khokhlov-Zabolotskaya-Kuznetsov) KZK equations for a focal intensity of 7 kW/cm(2). Results indicate that this approach could accurately describe the nonlinear acoustic field in the focal region with less computation time. The proposed modeling approach is shown to accurately describe the nonlinear acoustic field in the focal region. Compared with the Westervelt equation, the computation time of this approach is significantly reduced. It might also be applicable for the widely used concave focused transmitter with a large aperture angle.
Hamilton, Mark F.
1990-12-01
This report discusses five projects all of which involve basic theoretical research in nonlinear acoustics: (1) pulsed finite amplitude sound beams are studied with a recently developed time domain computer algorithm that solves the KZK nonlinear parabolic wave equation; (2) nonlinear acoustic wave propagation in a liquid layer is a study of harmonic generation and acoustic soliton information in a liquid between a rigid and a free surface; (3) nonlinear effects in asymmetric cylindrical sound beams is a study of source asymmetries and scattering of sound by sound at high intensity; (4) effects of absorption on the interaction of sound beams is a completed study of the role of absorption in second harmonic generation and scattering of sound by sound; and (5) parametric receiving arrays is a completed study of parametric reception in a reverberant environment.
Ion acoustic waves in pair-ion plasma: Linear and nonlinear analyses
International Nuclear Information System (INIS)
Saeed, R.; Mushtaq, A.
2009-01-01
Linear and nonlinear properties of low frequency ion acoustic wave (IAW) in pair-ion plasma in the presence of electrons are investigated. The dispersion relation and Kadomtsev-Petviashvili equation for linear/nonlinear IAW are derived from sets of hydrodynamic equations where the ion pairs are inertial while electrons are Boltzmannian. The dispersion curves for various concentrations of electrons are discussed and compared with experimental results. The predicted linear IAW propagates at the same frequencies as those of the experimentally observed IAW if n e0 ∼10 4 cm -3 . It is found that nonlinear profile of the ion acoustic solitary waves is significantly affected by the percentage ratio of electron number density and temperature. It is also determined that rarefactive solitary waves can propagate in this system. It is hoped that the results presented in this study would be helpful in understanding the salient features of the finite amplitude localized ion acoustic solitary pulses in a laboratory fullerene plasma.
Ion-acoustic nonlinear periodic waves in electron-positron-ion plasma
International Nuclear Information System (INIS)
Chawla, J. K.; Mishra, M. K.
2010-01-01
Ion-acoustic nonlinear periodic waves, namely, ion-acoustic cnoidal waves have been studied in electron-positron-ion plasma. Using reductive perturbation method and appropriate boundary condition for nonlinear periodic waves, the Korteweg-de Vries (KdV) equation is derived for the system. The cnoidal wave solution of the KdV equation is discussed in detail. It is found that the frequency of the cnoidal wave is a function of its amplitude. It is also found that the positron concentration modifies the properties of the ion-acoustic cnoidal waves. The existence regions for ion-acoustic cnoidal wave in the parameters space (p,σ), where p and σ are the positron concentration and temperature ratio of electron to positron, are discussed in detail. In the limiting case these ion-acoustic cnoidal waves reduce to the ion-acoustic soliton solutions. The effect of other parameters on the characteristics of the nonlinear periodic waves is also discussed.
Experimental study of a hybrid electro-acoustic nonlinear membrane absorber
Bryk, P. Y.; Bellizzi, S.; Côte, R.
2018-06-01
A hybrid electro-acoustic nonlinear membrane absorber working as a nonlinear energy sink (here after named EA-NES) is described. The device is composed of a thin circular visco-elastic membrane working as an essentially cubic oscillator. One face of the membrane is coupled to the acoustic field to be reduced and the other face is enclosed. The enclosure includes a loudspeaker for the control of the acoustic pressure felt by the rear face of the membrane through proportional feedback control. An experimental set-up has been developed where the EA-NES is weakly coupled to a linear acoustic system. The linear acoustic system is an open-ended tube, coupled on one side to the EA-NES by a box, and on the other side to a source loudspeaker by another box. Only sinusoidal forcing is considered. It is shown that the EA-NES is able to perform resonance capture with the acoustic field, resulting in noise reduction by targeted energy transfer, and to operate in a large frequency band, tuning itself passively to any linear system. We demonstrate the ability of the feedback gain defining the active loop to modify the resonance frequency of the EA-NES, which is a key factor to tune the triggering threshold of energy pumping. The novelty of this work is to use active control combined to passive nonlinear transfer energy to improve it. In this paper, only experimental results are analyzed.
Acoustic multipath arrivals in the horizontal plane due to approaching nonlinear internal waves.
Badiey, Mohsen; Katsnelson, Boris G; Lin, Ying-Tsong; Lynch, James F
2011-04-01
Simultaneous measurements of acoustic wave transmissions and a nonlinear internal wave packet approaching an along-shelf acoustic path during the Shallow Water 2006 experiment are reported. The incoming internal wave packet acts as a moving frontal layer reflecting (or refracting) sound in the horizontal plane. Received acoustic signals are filtered into acoustic normal mode arrivals. It is shown that a horizontal multipath interference is produced. This has previously been called a horizontal Lloyd's mirror. The interference between the direct path and the refracted path depends on the mode number and frequency of the acoustic signal. A mechanism for the multipath interference is shown. Preliminary modeling results of this dynamic interaction using vertical modes and horizontal parabolic equation models are in good agreement with the observed data.
Model Equation for Acoustic Nonlinear Measurement of Dispersive Specimens at High Frequency
Zhang, Dong; Kushibiki, Junichi; Zou, Wei
2006-10-01
We present a theoretical model for acoustic nonlinearity measurement of dispersive specimens at high frequency. The nonlinear Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation governs the nonlinear propagation in the SiO2/specimen/SiO2 multi-layer medium. The dispersion effect is considered in a special manner by introducing the frequency-dependant sound velocity in the KZK equation. Simple analytic solutions are derived by applying the superposition technique of Gaussian beams. The solutions are used to correct the diffraction and dispersion effects in the measurement of acoustic nonlinearity of cottonseed oil in the frequency range of 33-96 MHz. Regarding two different ultrasonic devices, the accuracies of the measurements are improved to ±2.0% and ±1.3% in comparison with ±9.8% and ±2.9% obtained from the previous plane wave model.
Zhang, Zhen; Koroleva, I; Manevitch, L I; Bergman, L A; Vakakis, A F
2016-09-01
We study the dynamics and acoustics of a nonlinear lattice with fixed boundary conditions composed of a finite number of particles coupled by linear springs, undergoing in-plane oscillations. The source of the strongly nonlinearity of this lattice is geometric effects generated by the in-plane stretching of the coupling linear springs. It has been shown that in the limit of low energy the lattice gives rise to a strongly nonlinear acoustic vacuum, which is a medium with zero speed of sound as defined in classical acoustics. The acoustic vacuum possesses strongly nonlocal coupling effects and an orthogonal set of nonlinear standing waves [or nonlinear normal modes (NNMs)] with mode shapes identical to those of the corresponding linear lattice; in contrast to the linear case, however, all NNMs except the one with the highest wavelength are unstable. In addition, the lattice supports two types of waves, namely, nearly linear sound waves (termed "L waves") corresponding to predominantly axial oscillations of the particles and strongly nonlinear localized propagating pulses (termed "NL pulses") corresponding to predominantly transverse oscillating wave packets of the particles with localized envelopes. We show the existence of nonlinear nonreciprocity phenomena in the dynamics and acoustics of the lattice. Two opposite cases are examined in the limit of low energy. The first gives rise to nonreciprocal dynamics and corresponds to collective, spatially extended transverse loading of the lattice leading to the excitation of individual, predominantly transverse NNMs, whereas the second case gives rise to nonreciprocal acoutics by considering the response of the lattice to spatially localized, transverse impulse or displacement excitations. We demonstrate intense and recurring energy exchanges between a directly excited NNM and other NNMs with higher wave numbers, so that nonreciprocal energy exchanges from small-to-large wave numbers are established. Moreover, we show the
Nonlinear generation of zonal flows by ion-acoustic waves in a uniform magnetoplasma
International Nuclear Information System (INIS)
Shukla, Nitin; Shukla, P.K.
2010-01-01
It is shown that large-scale zonal flows (ZFs) can be excited by Reynolds stress of nonlinearly interacting random phase ion-acoustic waves (EIAWs) in a uniform magnetoplasma. Since ZFs are associated with poloidal sheared flows, they can tear apart short scale EIAW turbulence eddies, and hence contribute to the reduction of the cross-field turbulent transport in a magnetized plasma.
Generation and control of sound bullets with a nonlinear acoustic lens.
Spadoni, Alessandro; Daraio, Chiara
2010-04-20
Acoustic lenses are employed in a variety of applications, from biomedical imaging and surgery to defense systems and damage detection in materials. Focused acoustic signals, for example, enable ultrasonic transducers to image the interior of the human body. Currently however the performance of acoustic devices is limited by their linear operational envelope, which implies relatively inaccurate focusing and low focal power. Here we show a dramatic focusing effect and the generation of compact acoustic pulses (sound bullets) in solid and fluid media, with energies orders of magnitude greater than previously achievable. This focusing is made possible by a tunable, nonlinear acoustic lens, which consists of ordered arrays of granular chains. The amplitude, size, and location of the sound bullets can be controlled by varying the static precompression of the chains. Theory and numerical simulations demonstrate the focusing effect, and photoelasticity experiments corroborate it. Our nonlinear lens permits a qualitatively new way of generating high-energy acoustic pulses, which may improve imaging capabilities through increased accuracy and signal-to-noise ratios and may lead to more effective nonintrusive scalpels, for example, for cancer treatment.
Propagation of nonlinear ion acoustic wave with generation of long-wavelength waves
International Nuclear Information System (INIS)
Ohsawa, Yukiharu; Kamimura, Tetsuo
1978-01-01
The nonlinear propagation of the wave packet of an ion acoustic wave with wavenumber k 0 asymptotically equals k sub(De) (the electron Debye wavenumber) is investigated by computer simulations. From the wave packet of the ion acoustic wave, waves with long wavelengths are observed to be produced within a few periods for the amplitude oscillation of the original wave packet. These waves are generated in the region where the original wave packet exists. Their characteristic wavelength is of the order of the length of the wave packet, and their propagation velocity is almost equal to the ion acoustic speed. The long-wavelength waves thus produced strongly affect the nonlinear evolution of the original wave packet. (auth.)
Nonlinear acoustic/seismic waves in earthquake processes
International Nuclear Information System (INIS)
Johnson, Paul A.
2012-01-01
Nonlinear dynamics induced by seismic sources and seismic waves are common in Earth. Observations range from seismic strong ground motion (the most damaging aspect of earthquakes), intense near-source effects, and distant nonlinear effects from the source that have important consequences. The distant effects include dynamic earthquake triggering—one of the most fascinating topics in seismology today—which may be elastically nonlinearly driven. Dynamic earthquake triggering is the phenomenon whereby seismic waves generated from one earthquake trigger slip events on a nearby or distant fault. Dynamic triggering may take place at distances thousands of kilometers from the triggering earthquake, and includes triggering of the entire spectrum of slip behaviors currently identified. These include triggered earthquakes and triggered slow, silent-slip during which little seismic energy is radiated. It appears that the elasticity of the fault gouge—the granular material located between the fault blocks—is key to the triggering phenomenon.
Chauvin, A.; Monteil, M.; Bellizzi, S.; Côte, R.; Herzog, Ph.; Pachebat, M.
2018-03-01
A nonlinear vibroacoustic absorber (Nonlinear Energy Sink: NES), involving a clamped thin membrane made in Latex, is assessed in the acoustic domain. This NES is here considered as an one-port acoustic system, analyzed at low frequencies and for increasing excitation levels. This dynamic and frequency range requires a suitable experimental technique, which is presented first. It involves a specific impedance tube able to deal with samples of sufficient size, and reaching high sound levels with a guaranteed linear response thank's to a specific acoustic source. The identification method presented here requires a single pressure measurement, and is calibrated from a set of known acoustic loads. The NES reflection coefficient is then estimated at increasing source levels, showing its strong level dependency. This is presented as a mean to understand energy dissipation. The results of the experimental tests are first compared to a nonlinear viscoelastic model of the membrane absorber. In a second step, a family of one degree of freedom models, treated as equivalent Helmholtz resonators is identified from the measurements, allowing a parametric description of the NES behavior over a wide range of levels.
NON-DESTRUCTIVE LEAK DETECTION IN GALVANIZED IRON PIPE USING NONLINEAR ACOUSTIC MODULATION METHOD
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Gigih Priyandoko
2018-02-01
Full Text Available Non-destructive testing is a wide group of analysis techniques used in science and industry to evaluate the properties of a structure without causing damage to it. The main objective of this project is to carry out experiment to detect leakage in pipeline using nonlinear acoustic modulation method. The nonlinear acoustic modulation approach with low frequency excitation and high frequency acoustic wave is used to reveal modulations in the presence of leak. The pipe used in this experiment was galvanized iron pipe. The experiment is started with the experiment of undamaged specimen and followed by the experiment of damaged specimen with manually applied leak. The results obtained are being observed and the difference between the specimen without leak and with leak can be distinguished. The distance of the leak and the distance of the outlet detected is nearly accurate to the exact location which is leak at 4.0 m and outlet at 6.0 m. Therefore, the results demonstrate that leakage can be detected using nonlinear acoustic modulation, and proved the objective of distinguish the difference between the results of specimen without leak and with leak has succeeded. The damage detection process can be eased with the knowledge on the signal features.
Nonlinear ion acoustic waves in a quantum degenerate warm plasma with dust grains
International Nuclear Information System (INIS)
Dubinov, A. E.; Kolotkov, D. Yu.; Sazonkin, M. A.
2011-01-01
A study is made of the propagation of ion acoustic waves in a collisionless unmagnetized dusty plasma containing degenerate ion and electron gases at nonzero temperatures. In linear theory, a dispersion relation for isothermal ion acoustic waves is derived and an exact expression for the linear ion acoustic velocity is obtained. The dependence of the linear ion acoustic velocity on the dust density in a plasma is calculated. An analysis of the dispersion relation reveals parameter ranges in which the problem has soliton solutions. In nonlinear theory, an exact solution to the basic equations is found and examined. The analysis is carried out by Bernoulli’s pseudopotential method. The ranges of the phase velocities of periodic ion acoustic waves and the velocities of solitons are determined. It is shown that these ranges do not overlap and that the soliton velocity cannot be lower than the linear ion acoustic velocity. The profiles of the physical quantities in a periodic wave and in a soliton are evaluated, as well as the dependence of the critical velocity of solitons on the dust density in a plasma.
Nonlinear acoustic propagation of launch vehicle and military jet aircraft noise
Gee, Kent L.
2010-10-01
The noise from launch vehicles and high-performance military jet aircraft has been shown to travel nonlinearly as a result of an amplitude-dependent speed of sound. Because acoustic pressure compressions travel faster than rarefactions, the waveform steepens and shocks form. This process results in a very different (and readily audible) noise signature and spectrum than predicted by linear models. On-going efforts to characterize the nonlinearity using statistical and spectral measures are described with examples from recent static tests of solid rocket boosters and the F-22 Raptor.
Nonlinear theory of ion-acoustic waves in an ideal plasma with degenerate electrons
International Nuclear Information System (INIS)
Dubinov, A. E.; Dubinova, A. A.
2007-01-01
A nonlinear theory is constructed that describes steady-state ion-acoustic waves in an ideal plasma in which the electron component is a degenerate Fermi gas and the ion component is a classical gas. The parameter ranges in which such a plasma can exist are determined, and dispersion relations for ion-acoustic waves are obtained that make it possible to find the linear ion-acoustic velocity. Analytic gas-dynamic models of ion sound are developed for a plasma with the ion component as a cold, an isothermal, or an adiabatic gas, and moreover, the solutions to the equations of all the models are brought to a quadrature form. Profiles of a subsonic periodic and a supersonic solitary wave are calculated, and the upper critical Mach numbers of a solitary wave are determined. For a plasma with cold ions, the critical Mach number is expressed by an explicit exact formula
Nonlinear localized dust acoustic waves in a charge varying dusty plasma with nonthermal ions
International Nuclear Information System (INIS)
Tribeche, Mouloud; Amour, Rabia
2007-01-01
A numerical investigation is presented to show the existence, formation, and possible realization of large-amplitude dust acoustic (DA) solitary waves in a charge varying dusty plasma with nonthermal ions. These nonlinear localized structures are self-consistent solutions of the collisionless Vlasov equation with a population of fast particles. The spatial patterns of the variable charge DA solitary wave are significantly modified by the nonthermal effects. The results complement and provide new insights into previously published results on this problem
International Nuclear Information System (INIS)
Pieczonka, L; Ukowski, P; Klepka, A; Staszewski, W J; Uhl, T; Aymerich, F
2014-01-01
The nonlinear vibro-acoustic modulation technique is used for impact damage detection in light composite sandwich panels. The method utilizes piezo-based low-frequency vibration and high-frequency ultrasonic excitations. The work presented focuses on the analysis of modulation intensity. The results show that the method can be used for impact damage detection reliably separating damage-related from vibro-acoustic modulations from other intrinsic nonlinear modulations. (paper)
Concrete damage diagnosed using the non-classical nonlinear acoustic method
International Nuclear Information System (INIS)
Dao, Zhou; Xiao-Zhou, Liu; Xiu-Fen, Gong; E, Nazarov V; Li, Ma
2009-01-01
It is known that the strength of concrete is seriously affected by damage and cracking. In this paper, six concrete samples under different damage levels are studied. The experimental results show a linear dependence of the resonance frequency shift on strain amplitude at the fundamental frequency, and approximate quadratic dependence of the amplitudes of the second and third harmonics on strain amplitude at the fundamental frequency as well. In addition, the amplitude of the third harmonics is shown to increase with the increase of damage level, which is even higher than that of the second harmonics in samples with higher damage levels. These are three properties of non-classical nonlinear acoustics. The nonlinear parameters increase from 10 6 to 10 8 with damage level, and are more sensitive to the damage level of the concrete than the linear parameters obtained by using traditional acoustics methods. So, this method based on non-classical nonlinear acoustics may provide a better means of non-destructive testing (NDT) of concrete and other porous materials
Effects of heat exchange and nonlinearity on acoustic streaming in a vibrating cylindrical cavity.
Gubaidullin, Amir A; Yakovenko, Anna V
2015-06-01
Acoustic streaming in a gas filled cylindrical cavity subjected to the vibration effect is investigated numerically. Both thermally insulated walls and constant temperature walls are considered. The range of vibration frequencies from low frequencies, at which the process can be described by an approximate analytical solution, to high frequencies giving rise to strong nonlinear effects is studied. Frequencies lower than the resonant one are chosen, and nonlinearity is achieved due to the large amplitude. The problem is solved in an axisymmetric statement. The dependence of acoustic streaming in narrow channels at vibration frequencies lower than the resonant one on the type of thermal boundary conditions is shown. The streaming vortices' directions of rotation in the case of constant temperature walls are found to be opposite to those in the case of thermally insulated walls. Different nonlinear effects, which increase with the frequency of vibration, are obtained. Nonlinear effects manifesting as the nonuniformity of average temperature, pressure, and density are in turn found to be influencing the streaming velocity and streaming structure.
Zeqiri, Bajram; Cook, Ashley; Rétat, Lise; Civale, John; ter Haar, Gail
2015-04-01
The acoustic nonlinearity parameter, B/A, is an important parameter which defines the way a propagating finite amplitude acoustic wave progressively distorts when travelling through any medium. One measurement technique used to determine its value is the finite amplitude insertion substitution (FAIS) method which has been applied to a range of liquid, tissue and tissue-like media. Importantly, in terms of the achievable measurement uncertainties, it is a relative technique. This paper presents a detailed study of the method, employing a number of novel features. The first of these is the use of a large area membrane hydrophone (30 mm aperture) which is used to record the plane-wave component of the acoustic field. This reduces the influence of diffraction on measurements, enabling studies to be carried out within the transducer near-field, with the interrogating transducer, test cell and detector positioned close to one another, an attribute which assists in controlling errors arising from nonlinear distortion in any intervening water path. The second feature is the development of a model which estimates the influence of finite-amplitude distortion as the acoustic wave travels from the rear surface of the test cell to the detector. It is demonstrated that this can lead to a significant systematic error in B/A measurement whose magnitude and direction depends on the acoustic property contrast between the test material and the water-filled equivalent cell. Good qualitative agreement between the model and experiment is reported. B/A measurements are reported undertaken at (20 ± 0.5) °C for two fluids commonly employed as reference materials within the technical literature: Corn Oil and Ethylene Glycol. Samples of an IEC standardised agar-based tissue-mimicking material were also measured. A systematic assessment of measurement uncertainties is presented giving expanded uncertainties in the range ±7% to ±14%, expressed at a confidence level close to 95
Nonlinear generation of non-acoustic modes by low-frequency sound in a vibrationally relaxing gas
International Nuclear Information System (INIS)
Perelomova, A.
2010-01-01
Two dynamic equations referring to a weakly nonlinear and weakly dispersive flow of a gas in which molecular vibrational relaxation takes place, are derived. The first one governs an excess temperature associated with the thermal mode, and the second one describes variations in vibrational energy. Both quantities refer to non-wave types of gas motion. These variations are caused by the nonlinear transfer of acoustic energy into thermal mode and internal vibrational degrees of freedom of a relaxing gas. The final dynamic equations are instantaneous; they include a quadratic nonlinear acoustic source, reflecting the nonlinear character of interaction of low-frequency acoustic and non-acoustic motions of the fluid. All types of sound, periodic or aperiodic, may serve as an acoustic source of both phenomena. The low-frequency sound is considered in this study. Some conclusions about temporal behavior of non-acoustic modes caused by periodic and aperiodic sound are made. Under certain conditions, acoustic cooling takes place instead of heating. (author)
Linear and nonlinear ion-acoustic waves in nonrelativistic quantum plasmas with arbitrary degeneracy
Haas, Fernando; Mahmood, Shahzad
2015-11-01
Linear and nonlinear ion-acoustic waves are studied in a fluid model for nonrelativistic, unmagnetized quantum plasma with electrons with an arbitrary degeneracy degree. The equation of state for electrons follows from a local Fermi-Dirac distribution function and applies equally well both to fully degenerate and classical, nondegenerate limits. Ions are assumed to be cold. Quantum diffraction effects through the Bohm potential are also taken into account. A general coupling parameter valid for dilute and dense plasmas is proposed. The linear dispersion relation of the ion-acoustic waves is obtained and the ion-acoustic speed is discussed for the limiting cases of extremely dense or dilute systems. In the long-wavelength limit, the results agree with quantum kinetic theory. Using the reductive perturbation method, the appropriate Korteweg-de Vries equation for weakly nonlinear solutions is obtained and the corresponding soliton propagation is analyzed. It is found that soliton hump and dip structures are formed depending on the value of the quantum parameter for the degenerate electrons, which affect the phase velocities in the dispersive medium.
International Nuclear Information System (INIS)
Jackson, E J; Coussios, C-C; Cleveland, R O
2014-01-01
Thermal ablation by high intensity focused ultrasound (HIFU) has a great potential for the non-invasive treatment of solid tumours. Due to the high pressure amplitudes involved, nonlinear acoustic effects must be understood and the relevant medium property is the parameter of nonlinearity B/A. Here, B/A was measured in ex vivo bovine liver, over a heating/cooling cycle replicating temperatures reached during HIFU ablation, adapting a finite amplitude insertion technique, which also allowed for measurement of sound-speed and attenuation. The method measures the nonlinear progression of a plane wave through liver and B/A was chosen so that numerical simulations matched the measured waveforms. To create plane-wave conditions, sinusoidal bursts were transmitted by a 100 mm diameter 1.125 MHz unfocused transducer and measured using a 15 mm diameter 2.25 MHz broadband transducer in the near field. Attenuation and sound-speed were calculated using a reflected pulse from the smaller transducer using the larger transducer as the reflecting interface. Results showed that attenuation initially decreased with heating then increased after denaturation, the sound-speed initially increased with temperature and then decreased, and B/A showed an increase with temperature but no significant post-heating change. The B/A data disagree with other reports that show a significant change and we suggest that any nonlinear enhancement in the received ultrasound signal post-treatment is likely due to acoustic cavitation rather than changes in tissue nonlinearity. (paper)
Ion-acoustic cnoidal wave and associated non-linear ion flux in dusty plasma
Energy Technology Data Exchange (ETDEWEB)
Jain, S. L. [Poornima Group of Institution, Sitapura, Jaipur 302022 (India); Tiwari, R. S. [Regional College for Education, Research and Technology, Jaipur 302022 (India); Mishra, M. K. [Department of Physics, University of Rajasthan, Jaipur 302004 (India)
2012-10-15
Using reductive perturbation method with appropriate boundary conditions, coupled evolution equations for first and second order potentials are derived for ion-acoustic waves in a collisionless, un-magnetized plasma consisting of hot isothermal electrons, cold ions, and massive mobile charged dust grains. The boundary conditions give rise to renormalization term, which enable us to eliminate secular contribution in higher order terms. Determining the non secular solution of these coupled equations, expressions for wave phase velocity and averaged non-linear ion flux associated with ion-acoustic cnoidal wave are obtained. Variation of the wave phase velocity and averaged non-linear ion flux as a function of modulus (k{sup 2}) dependent wave amplitude are numerically examined for different values of dust concentration, charge on dust grains, and mass ratio of dust grains with plasma ions. It is found that for a given amplitude, the presence of positively (negatively) charged dust grains in plasma decreases (increases) the wave phase velocity. This behavior is more pronounced with increase in dust concentrations or increase in charge on dust grains or decrease in mass ratio of dust grains. The averaged non-linear ion flux associated with wave is positive (negative) for negatively (positively) charged dust grains in the plasma and increases (decreases) with modulus (k{sup 2}) dependent wave amplitude. For given amplitude, it increases (decreases) as dust concentration or charge of negatively (positively) charged dust grains increases in the plasma.
Nonlinear vibration and radiation from a panel with transition to chaos induced by acoustic waves
Maestrello, Lucio; Frendi, Abdelkader; Brown, Donald E.
1992-01-01
The dynamic response of an aircraft panel forced at resonance and off-resonance by plane acoustic waves at normal incidence is investigated experimentally and numerically. Linear, nonlinear (period doubling) and chaotic responses are obtained by increasing the sound pressure level of the excitation. The response time history is sensitive to the input level and to the frequency of excitation. The change in response behavior is due to a change in input conditions, triggered either naturally or by modulation of the bandwidth of the incident waves. Off-resonance, bifurcation is diffused and difficult to maintain, thus the panel response drifts into a linear behavior. The acoustic pressure emanated by the panel is either linear or nonlinear as is the vibration response. The nonlinear effects accumulate during the propagation with distance. Results are also obtained on the control of the panel response using damping tape on aluminum panel and using a graphite epoxy panel having the same size and weight. Good agreement is obtained between the experimental and numerical results.
Nonlinear focal shift beyond the geometrical focus in moderately focused acoustic beams.
Camarena, Francisco; Adrián-Martínez, Silvia; Jiménez, Noé; Sánchez-Morcillo, Víctor
2013-08-01
The phenomenon of the displacement of the position along the axis of the pressure, intensity, and radiation force maxima of focused acoustic beams under increasing driving voltages (nonlinear focal shift) is studied for the case of a moderately focused beam. The theoretical and experimental results show the existence of this shift along the axis when the initial pressure in the transducer increases until the acoustic field reaches the fully developed nonlinear regime of propagation. Experimental data show that at high amplitudes and for moderate focusing, the position of the on-axis pressure maximum and radiation force maximum can surpass the geometrical focal length. On the contrary, the on-axis pressure minimum approaches the transducer under increasing driving voltages, increasing the distance between the positive and negative peak pressure in the beam. These results are in agreement with numerical KZK model predictions and the existed data of other authors and can be explained according to the effect of self-refraction characteristic of the nonlinear regime of propagation.
Diaz, Manuel A.; Solovchuk, Maxim A.; Sheu, Tony W. H.
2018-06-01
A nonlinear system of partial differential equations capable of describing the nonlinear propagation and attenuation of finite amplitude perturbations in thermoviscous media is presented. This system constitutes a full nonlinear wave model that has been formulated in the conservation form. Initially, this model is investigated analytically in the inviscid limit where it has been found that the resulting flux function fulfills the Lax-Wendroff theorem, and the scheme can match the solutions of the Westervelt and Burgers equations numerically. Here, high-order numerical descriptions of strongly nonlinear wave propagations become of great interest. For that matter we consider finite difference formulations of the weighted essentially non-oscillatory (WENO) schemes associated with explicit strong stability preserving Runge-Kutta (SSP-RK) time integration methods. Although this strategy is known to be computationally demanding, it is found to be effective when implemented to be solved in graphical processing units (GPUs). As we consider wave propagations in unbounded domains, perfectly matching layers (PML) have been also considered in this work. The proposed system model is validated and illustrated by using one- and two-dimensional benchmark test cases proposed in the literature for nonlinear acoustic propagation in homogeneous thermoviscous media.
Vibro-acoustic and nonlinear analysis of cadavric femoral bone impaction in cavity preparations
Directory of Open Access Journals (Sweden)
Oberst Sebastian
2018-01-01
Tikhonov regularisation, as inverse deconvolution technique, is applied to calculate the acoustic transfer functions from the acoustic responses and their mechanical impacts. The extracted spectra highlight that system characteristics altered during the cavity preparation process: in the high-frequency range the number of resonances increased with impacts and broach size. By applying nonlinear time series analysis the system dynamics increase in complexity and demand for a larger minimum embedding dimension. The growing number of resonances with similar level of the transfer function indicates a higher propensity to dissipate energy over sound; the change in embedding dimension indicates a decrease in linearity. The spectral changes as well as the altered dimension requirements indicate either an improved coupling between the bone and the broach or the onset of micro-fractures caused by growing stress levels within the bone.
International Nuclear Information System (INIS)
Jeong, Hyunjo; Zhang, Shuzeng; Li, Xiongbing; Barnard, Dan
2015-01-01
The accurate measurement of acoustic nonlinearity parameter β for fluids or solids generally requires making corrections for diffraction effects due to finite size geometry of transmitter and receiver. These effects are well known in linear acoustics, while those for second harmonic waves have not been well addressed and therefore not properly considered in previous studies. In this work, we explicitly define the attenuation and diffraction corrections using the multi-Gaussian beam (MGB) equations which were developed from the quasilinear solutions of the KZK equation. The effects of making these corrections are examined through the simulation of β determination in water. Diffraction corrections are found to have more significant effects than attenuation corrections, and the β values of water can be estimated experimentally with less than 5% errors when the exact second harmonic diffraction corrections are used together with the negligible attenuation correction effects on the basis of linear frequency dependence between attenuation coefficients, α 2 ≃ 2α 1
Jeong, Hyunjo; Zhang, Shuzeng; Barnard, Dan; Li, Xiongbing
2015-09-01
The accurate measurement of acoustic nonlinearity parameter β for fluids or solids generally requires making corrections for diffraction effects due to finite size geometry of transmitter and receiver. These effects are well known in linear acoustics, while those for second harmonic waves have not been well addressed and therefore not properly considered in previous studies. In this work, we explicitly define the attenuation and diffraction corrections using the multi-Gaussian beam (MGB) equations which were developed from the quasilinear solutions of the KZK equation. The effects of making these corrections are examined through the simulation of β determination in water. Diffraction corrections are found to have more significant effects than attenuation corrections, and the β values of water can be estimated experimentally with less than 5% errors when the exact second harmonic diffraction corrections are used together with the negligible attenuation correction effects on the basis of linear frequency dependence between attenuation coefficients, α2 ≃ 2α1.
Directory of Open Access Journals (Sweden)
Paulo S. Varoto
2006-01-01
Full Text Available Flexible structures are frequently subjected to multiple inputs when in the field environment. The accurate determination of the system dynamic response to multiple inputs depends on how much information is available from the excitation sources that act on the system under study. Detailed information include, but are not restricted to appropriate characterization of the excitation sources in terms of their variation in time and in space for the case of distributed loads. Another important aspect related to the excitation sources is how inputs of different nature contribute to the measured dynamic response. A particular and important driving mechanism that can occur in practical situations is the parametric resonance. Another important input that occurs frequently in practice is related to acoustic pressure distributions that is a distributed type of loading. In this paper, detailed theoretical and experimental investigations on the dynamic response of a flexible cantilever beam carrying a tip mass to simultaneously applied external acoustic and parametric excitation signals have been performed. A mathematical model for transverse nonlinear vibration is obtained by employing Lagrange’s equations where important nonlinear effects such as the beam’s curvature and quadratic viscous damping are accounted for in the equation of motion. The beam is driven by two excitation sources, a sinusoidal motion applied to the beam’s fixed end and parallel to its longitudinal axis and a distributed sinusoidal acoustic load applied orthogonally to the beam’s longitudinal axis. The major goal here is to investigate theoretically as well as experimentally the dynamic behavior of the beam-lumped mass system under the action of these two excitation sources. Results from an extensive experimental work show how these two excitation sources interacts for various testing conditions. These experimental results are validated through numerically simulated results
International Nuclear Information System (INIS)
Abourabia, A.M.; Hassan, K.M.; Shahein, R.A.
2008-01-01
The formation of (1+1) dimensional ion-acoustic waves (IAWs) in an unmagnetized collisionless plasma consisting of warm ions and isothermal distributed electrons is investigated. The electrodynamics system of equations are solved analytically in terms of a new variable ξκ χ -φ τ, where k=k(ω) is a complex function, at a fixed position. The analytical calculations gives that the critical value σ = τ/τ ∼ 0.25 distinguishes between the linear and nonlinear characters of IAW within the nanosecond time scale. The flow velocity, pressure, number density, electric potential, electric field, mobility and the total energy in the system are estimated and illustrated
1974-02-14
when 1 = 0, 5n - 0, ’Y is the ratio of specific heats, v the kinematic viscosity and v’ the thermometric conductivity. S is the cross sectional area of...particles of aluminum were suspended in a xylol filled glass cylinder. The circulatory nature is clearly indicated. In another technique, Zarembo and... aluminum (from Liebermann [ I I I). uses Eq. (3.49) for Uac, under the assumption that the cross sectional area of forward streaming is identical to the
Spectro-spatial analysis of wave packet propagation in nonlinear acoustic metamaterials
Zhou, W. J.; Li, X. P.; Wang, Y. S.; Chen, W. Q.; Huang, G. L.
2018-01-01
The objective of this work is to analyze wave packet propagation in weakly nonlinear acoustic metamaterials and reveal the interior nonlinear wave mechanism through spectro-spatial analysis. The spectro-spatial analysis is based on full-scale transient analysis of the finite system, by which dispersion curves are generated from the transmitted waves and also verified by the perturbation method (the L-P method). We found that the spectro-spatial analysis can provide detailed information about the solitary wave in short-wavelength region which cannot be captured by the L-P method. It is also found that the optical wave modes in the nonlinear metamaterial are sensitive to the parameters of the nonlinear constitutive relation. Specifically, a significant frequency shift phenomenon is found in the middle-wavelength region of the optical wave branch, which makes this frequency region behave like a band gap for transient waves. This special frequency shift is then used to design a direction-biased waveguide device, and its efficiency is shown by numerical simulations.
Kim, Gun; Kim, Jin-Yeon; Kurtis, Kimberly E.; Jacobs, Laurence J.
2015-03-01
This research experimentally investigates the sensitivity of the acoustic nonlinearity parameter to microcracks in cement-based materials. Based on the second harmonic generation (SHG) technique, an experimental setup using non-contact, air-coupled detection is used to receive the consistent Rayleigh surface waves. To induce variations in the extent of microscale cracking in two types of specimens (concrete and mortar), shrinkage reducing admixture (SRA), is used in one set, while a companion specimen is prepared without SRA. A 50 kHz wedge transducer and a 100 kHz air-coupled transducer are implemented for the generation and detection of nonlinear Rayleigh waves. It is shown that the air-coupled detection method provides more repeatable fundamental and second harmonic amplitudes of the propagating Rayleigh waves. The obtained amplitudes are then used to calculate the relative nonlinearity parameter βre, the ratio of the second harmonic amplitude to the square of the fundamental amplitude. The experimental results clearly demonstrate that the nonlinearity parameter (βre) is highly sensitive to the microstructural changes in cement-based materials than the Rayleigh phase velocity and attenuation and that SRA has great potential to avoid shrinkage cracking in cement-based materials.
Development of a Nonlinear Acoustic Phased Array and its Interaction with Thin Plates
Anzel, Paul; Donahue, Carly; Daraio, Chiara
2015-03-01
Numerous technologies are based on the principle of focusing acoustic energy. We propose a new device to focus sound waves which exploits highly nonlinear dynamics. The advantages of this device are the capability of generating very highly powerful acoustic pulses and potential operation in high-temperature environments where traditional piezoelectrics may fail. This device is composed of rows of ball bearings placed in contact with a medium of interest and with an actuator on the top. Elastic spherical particles have a contact force that grows with their relative displacement to the three-halves power (Hertzian contact). When several spheres are placed in a row, the particles support the propagation of ``solitary waves''--strong, compact stress-wave pulses whose tendency to disperse is counteracted by the nonlinearity of the sphere's contact force. We present results regarding the experimental operation of the device and its comparison to theory and numerical simulations. We will show how well this system is capable of focusing energy at various locations in the medium, and the limits imposed by pre-compression. Finally, the effects of timing error on energy focusing will be demonstrated. This research has been supported by a NASA Space Technology Research Fellowship.
Numerical Calculation and Measurement of Nonlinear Acoustic Fields in Ultrasound Diagnosis
Kawagishi, Tetsuya; Saito, Shigemi; Mine, Yoshitaka
2002-05-01
In order to develop a tool for designing on the ultrasonic probe and its peripheral devices for tissue-harmonic-imaging systems, a study is carried out to compare the calculation and observation results of nonlinear acoustic fields for a diagnostic ultrasound system. The pulsed ultrasound with a center frequency of 2.5 MHz is emanated from a weakly focusing sector probe with a 6.5 mm aperture radius and a 50 mm focal length into an agar phantom with an attenuation coefficient of about 0.6 dB/cm/MHz or 1.2 dB/cm/MHz. The nonlinear acoustic field is measured using a needle-type hydrophone. The calculation is based on the Khokhlov-Zabolotskaya-Kuznetsov(KZK) equation which is modified so that the frequency dependence of the attenuation coefficient is the same as that in biological tissue. This equation is numerically solved with the implicit backward method employing the iterative method. The measured and calculated amplitude spectra show good agreement with each other.
HIGH-PRECISION PREDICTIONS FOR THE ACOUSTIC SCALE IN THE NONLINEAR REGIME
International Nuclear Information System (INIS)
Seo, Hee-Jong; Eckel, Jonathan; Eisenstein, Daniel J.; Mehta, Kushal; Metchnik, Marc; Pinto, Phillip; Xu Xiaoying; Padmanabhan, Nikhil; Takahashi, Ryuichi; White, Martin
2010-01-01
We measure shifts of the acoustic scale due to nonlinear growth and redshift distortions to a high precision using a very large volume of high-force-resolution simulations. We compare results from various sets of simulations that differ in their force, volume, and mass resolution. We find a consistency within 1.5σ for shift values from different simulations and derive shift α(z) - 1 = (0.300 ± 0.015) %[D(z)/D(0)] 2 using our fiducial set. We find a strong correlation with a non-unity slope between shifts in real space and in redshift space and a weak correlation between the initial redshift and low redshift. Density-field reconstruction not only removes the mean shifts and reduces errors on the mean, but also tightens the correlations. After reconstruction, we recover a slope of near unity for the correlation between the real and redshift space and restore a strong correlation between the initial and the low redshifts. We derive propagators and mode-coupling terms from our N-body simulations and compare with the Zel'dovich approximation and the shifts measured from the χ 2 fitting, respectively. We interpret the propagator and the mode-coupling term of a nonlinear density field in the context of an average and a dispersion of its complex Fourier coefficients relative to those of the linear density field; from these two terms, we derive a signal-to-noise ratio of the acoustic peak measurement. We attempt to improve our reconstruction method by implementing 2LPT and iterative operations, but we obtain little improvement. The Fisher matrix estimates of uncertainty in the acoustic scale is tested using 5000 h -3 Gpc 3 of cosmological Particle-Mesh simulations from Takahashi et al. At an expected sample variance level of 1%, the agreement between the Fisher matrix estimates based on Seo and Eisenstein and the N-body results is better than 10%.
Energy Technology Data Exchange (ETDEWEB)
Singh, Rishi Pal [Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Singh, Rajendra Kumar, E-mail: rksingh_17@rediffmail.com [Department of Physics, Banaras Hindu University, Varanasi 221005 (India)
2010-11-01
Temperature dependence of acoustic attenuation and non-linearity parameters in lithium hydride and lithium deuteride have been studied for longitudinal and shear modes along various crystallographic directions of propagation in a wide temperature range. Lattice parameter and repulsive parameters have been used as input data and interactions up to next nearest neighbours have been considered to calculate second and third order elastic constants which in turn have been used for evaluating acoustic attenuation and related parameters. The results have been discussed and compared with available data. It is hoped that the present results will serve to stimulate the determination of the acoustic attenuation of these compounds at different temperatures.
Korman, M. S.; Duong, D. V.; Kalsbeck, A. E.
2015-10-01
An apparatus (SPO), designed to study flexural vibrations of a soil loaded plate, consists of a thin circular elastic clamped plate (and cylindrical wall) supporting a vertical soil column. A small magnet attached to the center of the plate is driven by a rigid AC coil (located coaxially below the plate) to complete the electrodynamic soil plate oscillator SPO design. The frequency dependent mechanical impedance Zmech (force / particle velocity, at the plate's center) is inversely proportional to the electrical motional impedance Zmot. Measurements of Zmot are made using the complex output to input response of a Wheatstone bridge that has an identical coil element in one of its legs. Near resonance, measurements of Zmot (with no soil) before and after a slight point mass loading at the center help determine effective mass, spring, damping and coupling constant parameters of the system. "Tuning curve" behavior of real{ Zmot } and imaginary{ Zmot } at successively higher vibration amplitudes of dry sifted masonry sand are measured. They exhibit a decrease "softening" in resonance frequency along with a decrease in the quality Q factor. In soil surface vibration measurements a bilinear hysteresis model predicts the tuning curve shape for this nonlinear mesoscopic elastic SPO behavior - which also models the soil vibration over an actual plastic "inert" VS 1.6 buried landmine. Experiments are performed where a buried 1m cube concrete block supports a 12 inch deep by 30 inch by 30 inch concrete soil box for burying a VS 1.6 in dry sifted masonry sand for on-the-mine and off-the-mine soil vibration experiments. The backbone curve (a plot of the peak amplitude vs. corresponding resonant frequency from a family of tuning curves) exhibits mostly linear behavior for "on target" soil surface vibration measurements of the buried VS 1.6 or drum-like mine simulants for relatively low particle velocities of the soil. Backbone curves for "on target" measurements exhibit
Nonlinear electrostatic ion-acoustic "oscilliton" waves driven by charge non-neutrality effects
Directory of Open Access Journals (Sweden)
J. Z. G. Ma
2011-01-01
Full Text Available Nonlinear "oscilliton" structures features a low-frequency (LF solitary envelope, the amplitude of which is modulated violently by superimposed high-frequency (HF oscillations. We have studied the charge non-neutrality effects on the excitation of electrostatic ion-acoustic (IA oscillitons. A two-fluid, warm plasma model is employed, and a set of nonlinear self-similar equations is solved in a cylindrical geometry. Under charge-neutrality conditions, three conventional IA structures (namely, sinusoidal, sawtooth, and spicky/bipolar are obtained. By contrast, under charge non-neutrality conditions, oscilliton structures are excited, where the LF envelope is in the sound-wave (SW mode, while the HF ingredients include the IA mode and the ion-Langmiur (IL mode. The amplitudes of the SW wave are violently modulated by the IA oscillations, whereas the upward sides of the IA amplitudes are modulated by the IL oscillations of smaller amplitudes, and the downward sides are modulated by hybrid IA/IL oscillations. The nonlinear oscillitons are found to be dependent not only upon the input parameters (e.g., the Mach number, the Debye length, and the initial temperature of particles, but on initial conditions as well.
International Nuclear Information System (INIS)
Balashova, E.V.; Lemanov, V.V.; Sherman, A.B.
1986-01-01
Generation process of a surface acoustic wave with summarized frequency in collinear propagation of two surface acoustic waves in SrTiO 3 crystal near crystal-phase transition O n → D 4h (T c ≅ 105 K) is investigated. Anomalous increase of a nonlinear parameter Γ ∼ (T-T c ) -1 attributed to a fluctuation mechanism is observed. It is shown that the presence of a surface layer in SrTiO 3 having a higher, than in crystal volume, temperature of phase transition results in summarized frequency signal oscillation
Pineyro, B.; Snively, J. B.
2017-12-01
Recent 1D and 2D nonlinear atmospheric models have provided important insight into acoustic waves generated by seismic events, which may steepen into shocks or saw-tooth trains while also dissipating strongly in the thermosphere [e.g., Chum et al., JGR, 121, 2016; Zettergren et al., JGR, 122, 2017]. Although they have yield results that agree with with observations of ionospheric perturbations, dynamical models for the diffusive and stratified lower thermosphere [e.g., Snively and Pasko, JGR, 113, 2008] often use single gas approximations with height-dependent physical properties (e.g. mean molecular weight, specific heats) that do not vary with time (fixed composition). This approximation is simpler and less computationally expensive than a true multi-fluid model, yet captures the important physical transition between molecular and atomic gases in the lower thermosphere. Models with time-dependent composition and properties have been shown to outperform commonly used models with fixed properties; these time-dependent effects have been included in a one-gas model by adding an advection equation for the molecular weight, finding closer agreement to a true binary-gas model [Walterscheid and Hickey, JGR, 106, 2001 and JGR, 117, 2012]. Here, a one-dimensional nonlinear mass fraction approach to multi-constituent gas modeling, motivated by the results of Walterscheid and Hickey [2001, 2012], is presented. The finite volume method of Bale et al. [SIAM JSC, 24, 2002] is implemented in Clawpack [http://www.clawpack.org; LeVeque, 2002] with a Riemann Solver to solve the Euler Equations including multiple species, defined by their mass fractions, as they undergo advection. Viscous dissipation and thermal conduction are applied via a fractional step method. The model is validated with shock tube problems for two species, and then applied to investigate propagating nonlinear acoustic waves from ground to thermosphere, such as following the 2011 Tohoku Earthquake [e
Energy Technology Data Exchange (ETDEWEB)
Guo, Shimin, E-mail: gsm861@126.com [School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, 710049 (China); Research Group MAC, Centrum Wiskunde and Informatica, Amsterdam, 1098XG (Netherlands); Mei, Liquan, E-mail: lqmei@mail.xjtu.edu.cn [School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, 710049 (China); Center for Computational Geosciences, Xi’an Jiaotong University, Xi’an, 710049 (China); Sun, Anbang [Research Group MAC, Centrum Wiskunde and Informatica, Amsterdam, 1098XG (Netherlands)
2013-05-15
The nonlinear propagation of planar and nonplanar (cylindrical and spherical) ion-acoustic waves in an unmagnetized electron–positron–ion–dust plasma with two-electron temperature distributions is investigated in the context of the nonextensive statistics. Using the reductive perturbation method, a modified nonlinear Schrödinger equation is derived for the potential wave amplitude. The effects of plasma parameters on the modulational instability of ion-acoustic waves are discussed in detail for planar as well as for cylindrical and spherical geometries. In addition, for the planar case, we analyze how the plasma parameters influence the nonlinear structures of the first- and second-order ion-acoustic rogue waves within the modulational instability region. The present results may be helpful in providing a good fit between the theoretical analysis and real applications in future spatial observations and laboratory plasma experiments. -- Highlights: ► Modulational instability of ion-acoustic waves in a new plasma model is discussed. ► Tsallis’s statistics is considered in the model. ► The second-order ion-acoustic rogue wave is studied for the first time.
International Nuclear Information System (INIS)
Guo, Shimin; Mei, Liquan; Sun, Anbang
2013-01-01
The nonlinear propagation of planar and nonplanar (cylindrical and spherical) ion-acoustic waves in an unmagnetized electron–positron–ion–dust plasma with two-electron temperature distributions is investigated in the context of the nonextensive statistics. Using the reductive perturbation method, a modified nonlinear Schrödinger equation is derived for the potential wave amplitude. The effects of plasma parameters on the modulational instability of ion-acoustic waves are discussed in detail for planar as well as for cylindrical and spherical geometries. In addition, for the planar case, we analyze how the plasma parameters influence the nonlinear structures of the first- and second-order ion-acoustic rogue waves within the modulational instability region. The present results may be helpful in providing a good fit between the theoretical analysis and real applications in future spatial observations and laboratory plasma experiments. -- Highlights: ► Modulational instability of ion-acoustic waves in a new plasma model is discussed. ► Tsallis’s statistics is considered in the model. ► The second-order ion-acoustic rogue wave is studied for the first time
Comparison of procedures for determination of acoustic nonlinearity of some inhomogeneous materials
DEFF Research Database (Denmark)
Jensen, Leif Bjørnø
1983-01-01
for an evaluation of the second order nonlinearity ratio B/A as a tissue characterizing parameter on a par with attenuation, impedance, etc. The several techniques used for the determination of B/A roughly fall into two main groups, finite-amplitude methods and thermo-dynamic-acoustic methods. The B/A values...... determined using various techniques of the two main groups are strongly scattered, showing a dependence on the procedure used, which makes it difficult to draw any valid conclusions. The paper discusses advantages and disadvantages of the techniques used hitherto, aiming at an explanation of the reasons...... for the deviations between the present B/A results for biological media. The necessary accuracy in the determination and the reliability in the exploitation of B/A as a tissue characterizing parameter for clinical use are emphasized....
Nonlinear acoustic waves in nonthermal plasmas with negative and positive dust
International Nuclear Information System (INIS)
Verheest, Frank
2009-01-01
Using a Sagdeev pseudopotential formalism where nonlinear structures are stationary in a co-moving frame, large dust-acoustic solitary waves and double layers have been studied in plasmas with negative and positive cold dust, in the presence of nonthermal electrons and ions. This has been done in a systematic way, to delimit the compositional parameter space in which such modes can be found. The existence domain of negative/positive solitary waves is limited by infinite compression of the negative/positive dust or by the occurrence of negative/positive double layers. These double layers require a sufficient nonthermality of the electrons/ions and the presence of enough positive/negative dust. There are parameter ranges where both negative and positive solitary structures coexist, sometimes both of the solitary wave type, sometimes one a solitary wave and the other a double layer. Typical Sagdeev pseudopotentials and solitary wave profiles have been presented.
International Nuclear Information System (INIS)
Angelino, P; Bottino, A; Hatzky, R; Jolliet, S; Sauter, O; Tran, T M; Villard, L
2006-01-01
The mutual interactions of ion temperature gradient (ITG) driven modes, zonal flows and geodesic acoustic modes (GAM) in tokamak plasmas are investigated using a global nonlinear gyrokinetic formulation with totally unconstrained evolution of temperature gradient and profile. A series of numerical simulations with the same initial temperature and density profile specifications is performed using a sequence of ideal MHD equilibria differing only in the value of the total plasma current, in particular with identical magnetic shear profiles and shapes of magnetic surfaces. On top of a bursty or quasi-steady state behaviour the zonal flows oscillate at the GAM frequency. The amplitude of these oscillations increases with the value of the safety factor q, resulting in a less effective suppression of ITG turbulence by zonal flows at a lower plasma current. The turbulence-driven volume-averaged radial heat transport is found to scale inversely with the total plasma current
Sultana, S.; Schlickeiser, R.
2018-05-01
Fully nonlinear features of heavy ion-acoustic solitary waves (HIASWs) have been investigated in an astrophysical degenerate relativistic quantum plasma (ADRQP) containing relativistically degenerate electrons and non-relativistically degenerate light ion species, and non-degenerate heavy ion species. The pseudo-energy balance equation is derived from the fluid dynamical equations by adopting the well-known Sagdeev-potential approach, and the properties of arbitrary amplitude HIASWs are examined. The small amplitude limit for the propagation of HIASWs is also recovered. The basic features (width, amplitude, polarity, critical Mach number, speed, etc.) of HIASWs are found to be significantly modified by the relativistic effect of the electron species, and also by the variation of the number density of electron, light ion, and heavy ion species. The basic properties of HIASWs, that may propagated in some realistic astrophysical plasma systems (e.g., in white dwarfs), are briefly discussed.
Wideband excitation in nonlinear vibro-acoustic modulation for damage detection
Klepka, A.; Adamczyk, M.; Pieczonka, L.; Staszewski, W. J.
2016-04-01
The paper discusses the use of wideband excitation in nonlinear vibro-acoustic modulation technique (VAM) used for damage detection. In its original form, two mono-harmonic signals (low and high frequency) are used for excitation. The low frequency excitation is typically selected based on a modal analysis test and high frequency excitation is selected arbitrarily in the ultrasonic frequency range. This paper presents a different approach with use of wideband excitation signals. The proposed approach gives the possibility to simplify the testing procedure by omitting the modal test used to determine the value of low frequency excitation. Simultaneous use of wideband excitation for high frequency solves the ambiguity related to the selection of the frequency of acoustic wave. Broadband excitation signals require, however, more elaborate signal processing methods to determine the intensity of modulation for a given bandwidth. The paper discusses the proposed approach and the related signal processing procedure. Experimental validation of the proposed technique is performed on a laminated composite plate with a barely visible impact damage that was generated in an impact test. Piezoceramic actuators are used for vibration excitation and a scanning laser vibrometer is used for noncontact data acquisition.
Energy Technology Data Exchange (ETDEWEB)
Jeong, Hyunjo, E-mail: hjjeong@wku.ac.kr [Division of Mechanical and Automotive Engineering, Wonkwang University, Iksan, Jeonbuk 570-749 (Korea, Republic of); Zhang, Shuzeng; Li, Xiongbing [School of Traffic and Transportation Engineering, Central South University, Changsha, Hunan 410075 (China); Barnard, Dan [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50010 (United States)
2015-09-15
The accurate measurement of acoustic nonlinearity parameter β for fluids or solids generally requires making corrections for diffraction effects due to finite size geometry of transmitter and receiver. These effects are well known in linear acoustics, while those for second harmonic waves have not been well addressed and therefore not properly considered in previous studies. In this work, we explicitly define the attenuation and diffraction corrections using the multi-Gaussian beam (MGB) equations which were developed from the quasilinear solutions of the KZK equation. The effects of making these corrections are examined through the simulation of β determination in water. Diffraction corrections are found to have more significant effects than attenuation corrections, and the β values of water can be estimated experimentally with less than 5% errors when the exact second harmonic diffraction corrections are used together with the negligible attenuation correction effects on the basis of linear frequency dependence between attenuation coefficients, α{sub 2} ≃ 2α{sub 1}.
Energy Technology Data Exchange (ETDEWEB)
Han, Jiu-Ning, E-mail: hanjiuning@126.com; He, Yong-Lin; Luo, Jun-Hua; Nan, Ya-Gong; Han, Zhen-Hai; Dong, Guang-Xing [College of Physics and Electromechanical Engineering, Hexi University, Zhangye 734000 (China); Duan, Wen-Shan [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Li, Jun-Xiu [College of Civil Engineering, Hexi University, Zhangye 734000 (China)
2014-01-15
With the consideration of the superthermal electron distribution, we present a theoretical investigation about the nonlinear propagation of electron-acoustic solitary and shock waves in a dissipative, nonplanar non-Maxwellian plasma comprised of cold electrons, superthermal hot electrons, and stationary ions. The reductive perturbation technique is used to obtain a modified Korteweg-de Vries Burgers equation for nonlinear waves in this plasma. We discuss the effects of various plasma parameters on the time evolution of nonplanar solitary waves, the profile of shock waves, and the nonlinear structure induced by the collision between planar solitary waves. It is found that these parameters have significant effects on the properties of nonlinear waves and collision-induced nonlinear structure.
Hamilton, Mark F.
1989-08-01
Four projects are discussed in this annual summary report, all of which involve basic research in nonlinear acoustics: Scattering of Sound by Sound, a theoretical study of two nonconlinear Gaussian beams which interact to produce sum and difference frequency sound; Parametric Receiving Arrays, a theoretical study of parametric reception in a reverberant environment; Nonlinear Effects in Asymmetric Sound Beams, a numerical study of two dimensional finite amplitude sound fields; and Pulsed Finite Amplitude Sound Beams, a numerical time domain solution of the KZK equation.
Vorotnikov, K.; Starosvetsky, Y.
2018-01-01
The present study concerns two-dimensional nonlinear mechanisms of bidirectional and unidirectional channeling of longitudinal and shear waves emerging in the locally resonant acoustic structure. The system under consideration comprises an oscillatory chain of the axially coupled masses. Each mass of the chain is subject to the local linear potential along the lateral direction and incorporates the lightweight internal rotator. In the present work, we demonstrate the emergence of special resonant regimes of complete bi- and unidirectional transitions between the longitudinal and the shear waves of the locally resonant chain. These regimes are manifested by the two-dimensional energy channeling between the longitudinal and the shear traveling waves in the recurrent as well as the irreversible fashion. We show that the spatial control of the two dimensional energy flow between the longitudinal and the shear waves is solely governed by the motion of the internal rotators. Nonlinear analysis of the regimes of a bidirectional wave channeling unveils their global bifurcation structure and predicts the zones of their spontaneous transitions from a complete bi-directional wave channeling to the one-directional entrapment. An additional regime of a complete irreversible resonant transformation of the longitudinal wave into a shear wave is analyzed in the study. The intrinsic mechanism governing the unidirectional wave reorientation is described analytically. The results of the analysis of both mechanisms are substantiated by the numerical simulations of the full model and are found to be in a good agreement.
International Nuclear Information System (INIS)
Rao, N.N.
1998-01-01
A systematic analysis of the stationary propagation of nonlinearly coupled electromagnetic and ion-acoustic waves in an unmagnetized plasma via the ponderomotive force is carried out. For small but finite amplitudes, the governing equations have a Hamiltonian structure, but with a kinetic energy term that is not positive definite. The Hamiltonian is similar to the well-known Hacute enon endash Heiles Hamiltonian of nonlinear dynamics, and is completely integrable in three regimes of the allowed parameter space. The corresponding second invariants of motion are also explicitly obtained. The integrable parameter regimes correspond to supersonic values of the Mach number, which characterizes the propagation speed of the coupled waves. On the other hand, in the sub- as well as near-sonic regimes, the coupled mode equations admit different types of exact analytical solutions, which represent nonlinear localized eigenstates of the electromagnetic field trapped in the density cavity due to the ponderomotive potential. While the density cavity has always a single-dip structure, for larger amplitudes it can support higher-order modes having a larger number of nodes in the electromagnetic field. In particular, we show the existence of a new type of localized electromagnetic wave whose field intensity has a triple-hump structure. For typical parameter values, the triple-hump solitons propagate with larger Mach numbers that are closer to the sonic limit than the single- as well as the double-hump solitons, but carry a lesser amount of the electromagnetic field energy. A comparison between the different types of solutions is carried out. The possibility of the existence of trapped electromagnetic modes having a larger number of humps is also discussed. copyright 1998 American Institute of Physics
Effects of vortex-like and non-thermal ion distributions on non-linear dust-acoustic waves
International Nuclear Information System (INIS)
Mamun, A.A.; Cairns, R.A.; Shukla, P.K.
1996-01-01
The effects of vortex-like and non-thermal ion distributions are incorporated in the study of nonlinear dust-acoustic waves in an unmagnetized dusty plasma. It is found that owing to the departure from the Boltzmann ion distribution to a vortex-like phase space distribution, the dynamics of small but finite amplitude dust-acoustic waves is governed by a modified Kortweg endash de Vries equation. The latter admits a stationary dust-acoustic solitary wave solution, which has larger amplitude, smaller width, and higher propagation velocity than that involving adiabatic ions. On the other hand, consideration of a non-thermal ion distribution provides the possibility of coexistence of large amplitude rarefactive as well as compressive dust-acoustic solitary waves, whereas these structures appear independently when the wave amplitudes become infinitely small. The present investigation should help us to understand the salient features of the non-linear dust-acoustic waves that have been observed in a recent numerical simulation study. copyright 1996 American Institute of Physics
Elwakil, S. A.; El-hanbaly, A. M.; Elgarayh, A.; El-Shewy, E. K.; Kassem, A. I.
2014-11-01
The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, non-thermal hot electrons obeying a non-thermal distribution, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles on the electron beam and energetic population parameter are discussed. The results of the present investigation may be applicable in auroral zone plasma.
On the development and evolution of nonlinear ion acoustic wave packets
Directory of Open Access Journals (Sweden)
A. M. Hamza
2005-09-01
Full Text Available A simple model of ion fluctuations (ion acoustic and ion cyclotron fluctuations for example driven by an electron current which leads to intermittent fluctuations when the linear growth rate exceeds the wave packet dispersion rate is analized. The normalized fluctuation amplitude eφ0/T can be much larger than the mass ratio (me/mi level predicted by the conventional quasilinear theory or Manheimer's theory (see references in this document, and where φ0 represents the amplitude of the main peak of the ion fluctuations. Although the ion motion is linear, intermittency is produced by the strong nonlinear electron response, which causes the electron momentum input to the ion fluctuations to be spatially localized. We treat the 1-D case because it is especially simple from an intuitive and analytical point of view, but it is readily apparent and one can put forward the conjecture that the effect occurs in a three dimensional magnetized plasma. The 1-D analysis, as shown in this manuscript will clearly help identify the subtle difference between turbulence as conventionally understood and intermittency as it occurs in space and laboratory plasmas. Keywords. Meteorology and atmospheric dynamics (Turbulence – Ionosphere (Wave-particles interactions – Space plasma physics (Waves and instabilities
Kilian, Gladiné; Pieter, Muyshondt; Joris, Dirckx
2016-06-01
Laser Doppler Vibrometry is an intrinsic highly linear measurement technique which makes it a great tool to measure extremely small nonlinearities in the vibration response of a system. Although the measurement technique is highly linear, other components in the experimental setup may introduce nonlinearities. An important source of artificially introduced nonlinearities is the speaker, which generates the stimulus. In this work, two correction methods to remove the effects of stimulus nonlinearity are investigated. Both correction methods were found to give similar results but have different pros and cons. The aim of this work is to investigate the importance of the conical shape of the eardrum as a source of nonlinearity in hearing. We present measurements on flat and indented membranes. The data shows that the curved membrane exhibit slightly higher levels of nonlinearity compared to the flat membrane.
Jeong, Hyunjo; Zhang, Shuzeng; Barnard, Dan; Li, Xiongbing
2016-02-01
Measurements of the acoustic nonlinearity parameter β are frequently made for early detection of damage in various materials. The practical implementation of the measurement technique has been limited to the through-transmission setup for determining the nonlinearity parameter of the second harmonic wave. In this work, a feasibility study is performed to assess the possibility of using pulse-echo methods in determining the nonlinearity parameter β of solids with a stress-free boundary. The multi-Gaussian beam model is developed based on the quasilinear theory of the KZK equation. Simulation results and discussion are presented for the reflected beam fields of the fundamental and second harmonic waves, the uncorrected β behavior and the properties of total correction that incorporate reflection, attenuation and diffraction effects.
Nonlinear dust-acoustic structures in space plasmas with superthermal electrons, positrons, and ions
Energy Technology Data Exchange (ETDEWEB)
Saberian, E., E-mail: e.saberian@neyshabur.ac.ir [University of Neyshabur, Department of Physics, Faculty of Basic Sciences (Iran, Islamic Republic of); Esfandyari-Kalejahi, A.; Afsari-Ghazi, M. [Azarbaijan Shahid Madani University, Department of Physics, Faculty of Sciences (Iran, Islamic Republic of)
2017-01-15
Some features of nonlinear dust-acoustic (DA) structures are investigated in a space plasma consisting of superthermal electrons, positrons, and positive ions in the presence of negatively charged dust grains with finite-temperature by employing a pseudo-potential technique in a hydrodynamic model. For this purpose, it is assumed that the electrons, positrons, and ions obey a kappa-like (κ) distribution in the background of adiabatic dust population. In the linear analysis, it is found that the dispersion relation yield two positive DA branches, i.e., the slow and fast DA waves. The upper branch (fast DA waves) corresponds to the case in which both (negatively charged) dust particles and (positively charged) ion species oscillate in phase with electrons and positrons. On the other hand, the lower branch (slow DA waves) corresponds to the case in which only dust particles oscillate in phase with electrons and positrons, while ion species are in antiphase with them. On the other hand, the fully nonlinear analysis shows that the existence domain of solitons and their characteristics depend strongly on the dust charge, ion charge, dust temperature, and the spectral index κ. It is found that the minimum/maximum Mach number increases as the spectral index κ increases. Also, it is found that only solitons with negative polarity can propagate and that their amplitudes increase as the parameter κ increases. Furthermore, the domain of Mach number shifts to the lower values, when the value of the dust charge Z{sub d} increases. Moreover, it is found that the Mach number increases with an increase in the dust temperature. Our analysis confirms that, in space plasmas with highly charged dusts, the presence of superthermal particles (electrons, positrons, and ions) may facilitate the formation of DA solitary waves. Particularly, in two cases of hydrogen ions H{sup +} (Z{sub i} = 1) and doubly ionized Helium atoms He{sup 2+} (Z{sub i} = 2), the mentioned results are the same
Cantrell, John H., Jr.; Cantrell, Sean A.
2008-01-01
A comprehensive analytical model of the interaction of the cantilever tip of the atomic force microscope (AFM) with the sample surface is developed that accounts for the nonlinearity of the tip-surface interaction force. The interaction is modeled as a nonlinear spring coupled at opposite ends to linear springs representing cantilever and sample surface oscillators. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a standard iteration procedure. Solutions are obtained for the phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) techniques including force modulation microscopy, atomic force acoustic microscopy, ultrasonic force microscopy, heterodyne force microscopy, resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), and the commonly used intermittent contact mode (TappingMode) generally available on AFMs. The solutions are used to obtain a quantitative measure of image contrast resulting from variations in the Young modulus of the sample for the amplitude and phase images generated by the A-AFM techniques. Application of the model to RDF-AFUM and intermittent soft contact phase images of LaRC-cp2 polyimide polymer is discussed. The model predicts variations in the Young modulus of the material of 24 percent from the RDF-AFUM image and 18 percent from the intermittent soft contact image. Both predictions are in good agreement with the literature value of 21 percent obtained from independent, macroscopic measurements of sheet polymer material.
Chu, Dezhang; Lawson, Gareth L; Wiebe, Peter H
2016-05-01
The linear inversion commonly used in fisheries and zooplankton acoustics assumes a constant inversion kernel and ignores the uncertainties associated with the shape and behavior of the scattering targets, as well as other relevant animal parameters. Here, errors of the linear inversion due to uncertainty associated with the inversion kernel are quantified. A scattering model-based nonlinear inversion method is presented that takes into account the nonlinearity of the inverse problem and is able to estimate simultaneously animal abundance and the parameters associated with the scattering model inherent to the kernel. It uses sophisticated scattering models to estimate first, the abundance, and second, the relevant shape and behavioral parameters of the target organisms. Numerical simulations demonstrate that the abundance, size, and behavior (tilt angle) parameters of marine animals (fish or zooplankton) can be accurately inferred from the inversion by using multi-frequency acoustic data. The influence of the singularity and uncertainty in the inversion kernel on the inversion results can be mitigated by examining the singular values for linear inverse problems and employing a non-linear inversion involving a scattering model-based kernel.
International Nuclear Information System (INIS)
Jian-Jun, Chen; De, Zhang; Yi-Wei, Mao; Jian-Chun, Cheng
2009-01-01
We present a unique method to describe the bonding strength at a bonded solid–solid interface in a multilayered composite material by contact acoustic nonlinearity (CAN) parameter. A CAN model on the bonded solid–solid interface is depicted. It can be seen from the model that CAN parameter is very sensitive to the bonding strength at the interface. When an incident focusing acoustic longitudinal wave scans the interface in two dimensions, the transmitted wave can be used to extract CAN parameter. The contour of the bonding strength for a sample is obtained by CAN parameter. The results show that the region with weak bonding strength can be easily distinguished from the contour
Nonlinear dust-ion-acoustic waves in a multi-ion plasma with ...
Indian Academy of Sciences (India)
The basic features of such dust-ion-acoustic solitary and shock waves have been ... ion plasmas because of its vital role in understanding different types of ... cannot support the usual ion-acoustic waves, but can support the DIA waves of ...
Fissioning of nonlinear ion-acoustic rarefactive pulse in a homogeneous quiescent plasma
International Nuclear Information System (INIS)
Saxena, Y.C.; Mattoo, S.K.; Sekar, A.N.
1982-01-01
A finite amplitude rarefactive ion-acoustic wave is observed to fission resulting in two minima. After fissioning the two minima travel at different speeds, one at 0.8 Csub(s) and the other at 1.2 Csub(s), where Csub(s) is the ion-acoustic speed. (author)
Energy Technology Data Exchange (ETDEWEB)
Emadi, E.; Zahed, H. [Physics Department, Faculty of Science, Sahand University of Technology, 51335–1996 Tabriz (Iran, Islamic Republic of)
2016-08-15
The behavior of linear and nonlinear dust ion acoustic (DIA) solitary waves in an unmagnetized quantum dusty plasma, including inertialess electrons and positrons, ions, and mobile negative dust grains, are studied. Reductive perturbation and Sagdeev pseudopotential methods are employed for small and large amplitude DIA solitary waves, respectively. A minimum value of the Mach number obtained for the existence of solitary waves using the analytical expression of the Sagdeev potential. It is observed that the variation on the values of the plasma parameters such as different values of Mach number M, ion to electron Fermi temperature ratio σ, and quantum diffraction parameter H can lead to the creation of compressive solitary waves.
Linear and non-linear ion acoustic phenomena in magnetic multi-dipole discharges
International Nuclear Information System (INIS)
Ferreira, J.L.
1986-12-01
An experimental study of ion acoustic phenomena in a multi-magnetic-dipole plasma device is presented. The plasma is uniform and free from external field, permitting good observation of space and laboratory plasma phenomena. The major interest was in the observtion of the propagation characterics of solitions and ion acoustic waves in a double plasma configuration. In this experiment plane waves were studied in a plasma composed by a mixture of negative and positive ions. The most important result was the first observation of solitary waves with negative potential, that means rarefaction ion acoustic solitions. The formation of non neutral regions inside the plasma and its relations with the inhibition of electron thermal flux were studied. A bootstrap action enhances the ion acoustic instability which generates an anomalous resistivity self consistently with a potential step. It was observed that this is the mechanism of cold electron thermalization during diffusion through a warn collisionless plasma. The importance of the bootstrap action in ion acoustic double layer formation was experimentally verified by ion acoustic instability inhibition, obtained via induced Landau damping of the ion acoustic spectrum of the instability. (author) [pt
International Nuclear Information System (INIS)
Sabry, R.; Shukla, P. K.; Moslem, W. M.
2009-01-01
Properties of fully nonlinear ion-acoustic solitary waves in a plasma with positive-negative ions and nonthermal electrons are investigated. For this purpose, the hydrodynamic equations for the positive-negative ions, nonthermal electron density distribution, and the Poisson equation are used to derive the energy integral equation with a new Sagdeev potential. The latter is analyzed to examine the existence regions of the solitary pulses. It is found that the solitary excitations strongly depend on the mass and density ratios of the positive and negative ions as well as the nonthermal electron parameter. Numerical solution of the energy integral equation clears that both positive and negative potentials exist together. It is found that faster solitary pulses are taller and narrower. Furthermore, increasing the electron nonthermality parameter (negative-to-positive ions density ratio) decreases (increases) the localized excitation amplitude but increases (decreases) the pulse width. The present model is used to investigate the solitary excitations in the (H + ,O 2 - ) and (H + ,H - ) plasmas, where they are presented in the D- and F-regions of the Earth's ionosphere. This investigation should be helpful in understanding the salient features of the fully nonlinear ion-acoustic solitary waves in space and in laboratory plasmas where two distinct groups of ions and non-Boltzmann distributed electrons are present.
International Nuclear Information System (INIS)
Das, K.P.; Sihi, S.
1979-01-01
Assuming amplitudes as slowly varying functions of space and time and using perturbation method three coupled nonlinear partial differential equations are obtained for the nonlinear evolution of a three dimensional longitudinal plasma wave packet in a hot plasma including the effect of its interaction with a long wavelength ion-acoustic wave. These three equations are used to derive the instability conditions of a uniform longitudinal plasma wave train including the effect of its interaction both at resonance and nonresonance, with a long wavelength ion-acoustic wave. (author)
Nonlinear electron acoustic structures generated on the high-potential side of a double layer
Directory of Open Access Journals (Sweden)
R. Pottelette
2009-04-01
Full Text Available High-time resolution measurements of the electron distribution function performed in the auroral upward current region reveals a large asymmetry between the low- and high-potential sides of a double-layer. The latter side is characterized by a large enhancement of a locally trapped electron population which corresponds to a significant part (~up to 30% of the total electron density. As compared to the background hot electron population, this trapped component has a very cold temperature in the direction parallel to the static magnetic field. Accordingly, the differential drift between the trapped and background hot electron populations generates high frequency electron acoustic waves in a direction quasi-parallel to the magnetic field. The density of the trapped electron population can be deduced from the frequency where the electron acoustic spectrum maximizes. In the auroral midcavity region, the electron acoustic waves may be modulated by an additional turbulence generated in the ion acoustic range thanks to the presence of a pre-accelerated ion beam located on the high-potential side of the double layer. Electron holes characterized by bipolar pulses in the electric field are sometimes detected in correlation with these electron acoustic wave packets.
Glinka, Yuri D.; Babakiray, Sercan; Johnson, Trent A.; Holcomb, Mikel B.; Lederman, David
2016-09-01
Low-energy collective electronic excitations exhibiting sound-like linear dispersion have been intensively studied both experimentally and theoretically for a long time. However, coherent acoustic plasmon modes appearing in time-domain measurements are rarely observed due to Landau damping by the single-particle continua. Here we report on the observation of coherent acoustic Dirac plasmon (CADP) modes excited in indirectly (electrostatically) opposite-surface coupled films of the topological insulator Bi2Se3. Using transient second-harmonic generation, a technique capable of independently monitoring the in-plane and out-of-plane electron dynamics in the films, the GHz-range oscillations were observed without corresponding oscillations in the transient reflectivity. These oscillations were assigned to the transverse magnetic and transverse electric guided CADP modes induced by the evanescent guided Lamb acoustic waves and remained Landau undamped due to fermion tunnelling between the opposite-surface Dirac states.
Nonlinear dust acoustic waves in a charge varying dusty plasma with suprathermal electrons
International Nuclear Information System (INIS)
Tribeche, Mouloud; Bacha, Mustapha
2010-01-01
Arbitrary amplitude dust acoustic waves in a dusty plasma with a high-energy-tail electron distribution are investigated. The effects of charge variation and electron deviation from the Boltzmann distribution on the dust acoustic soliton are then considered. The dust charge variation makes the dust acoustic soliton more spiky. The dust grain surface collects less electrons as the latter evolves far away from their thermodynamic equilibrium. The dust accumulation caused by a balance of the electrostatic forces acting on the dust grains is more effective for lower values of the electron spectral index. Under certain conditions, the dust charge fluctuation may provide an alternate physical mechanism causing anomalous dissipation, the strength of which becomes important and may prevail over that of dispersion as the suprathermal character of the plasma becomes important. Our results may explain the strong spiky waveforms observed in auroral plasmas.
Energy Technology Data Exchange (ETDEWEB)
Lingvall, Fredrik; Ping Wu; Stepinski, Tadeusz [Uppsala Univ., (Sweden). Dept. of Materials Science
2003-03-01
This report contains results concerning inspection of copper canisters for spent nuclear fuel by means of ultrasound obtained at Signals and Systems, Uppsala University in year 2001/2002. The first chapter presents results of an investigation of a new method for synthetic aperture imaging. The new method presented here takes the form of a 2D filter based on minimum mean squared error (MMSE) criteria. The filter, which varies with the target position in two dimensions includes information about spatial impulse response (SIR) of the imaging system. Spatial resolution of the MMSE method is investigated and compared experimentally to that of the classical SAFT and phased array imaging. It is shown that the resolution of the MMSE algorithm, evaluated for imaging immersed copper specimen is superior to that observed for the two above-mentioned methods. Extended experimental and theoretical research concerning the potential of nonlinear waves and material harmonic imaging is presented in the second chapter. An experimental work is presented that was conducted using the RITEC RAM-5000 ultrasonic system capable of providing a high power tone-burst output. A new method for simulation of nonlinear acoustic waves that is a combination of the angular spectrum approach and the Burger's equation is also presented. This method was used for simulating nonlinear elastic waves radiated by the annular transducer that was used in the experiments.
International Nuclear Information System (INIS)
Lingvall, Fredrik; Ping Wu; Stepinski, Tadeusz
2003-03-01
This report contains results concerning inspection of copper canisters for spent nuclear fuel by means of ultrasound obtained at Signals and Systems, Uppsala University in year 2001/2002. The first chapter presents results of an investigation of a new method for synthetic aperture imaging. The new method presented here takes the form of a 2D filter based on minimum mean squared error (MMSE) criteria. The filter, which varies with the target position in two dimensions includes information about spatial impulse response (SIR) of the imaging system. Spatial resolution of the MMSE method is investigated and compared experimentally to that of the classical SAFT and phased array imaging. It is shown that the resolution of the MMSE algorithm, evaluated for imaging immersed copper specimen is superior to that observed for the two above-mentioned methods. Extended experimental and theoretical research concerning the potential of nonlinear waves and material harmonic imaging is presented in the second chapter. An experimental work is presented that was conducted using the RITEC RAM-5000 ultrasonic system capable of providing a high power tone-burst output. A new method for simulation of nonlinear acoustic waves that is a combination of the angular spectrum approach and the Burger's equation is also presented. This method was used for simulating nonlinear elastic waves radiated by the annular transducer that was used in the experiments
Lee, Victoria S.; Zhou, Xiao Ping; Rahn, Douglas A., III; Wang, Emily Q.; Jiang, Jack J.
2008-01-01
Nineteen PD patients who received deep brain stimulation (DBS), 10 non-surgical (control) PD patients, and 11 non-pathologic age- and gender-matched subjects performed sustained vowel phonations. The following acoustic measures were obtained on the sustained vowel phonations: correlation dimension (D[subscript 2]), percent jitter, percent shimmer,…
Imaging of human tooth using ultrasound based chirp-coded nonlinear time reversal acoustics
Czech Academy of Sciences Publication Activity Database
Dos Santos, S.; Převorovský, Zdeněk
2011-01-01
Roč. 51, č. 6 (2011), s. 667-674 ISSN 0041-624X Institutional research plan: CEZ:AV0Z20760514 Keywords : TR-NEWS * chirp-coded excitation * echodentography * ultrasonic imaging Subject RIV: BI - Acoustics Impact factor: 1.838, year: 2011 http://www.sciencedirect.com/science/article/pii/S0041624X11000229
Maraghechi, Borna; Kolios, Michael C; Tavakkoli, Jahan
2015-01-01
Hyperthermia is a cancer treatment technique that could be delivered as a stand-alone modality or in conjunction with chemotherapy or radiation therapy. Noninvasive and real-time temperature monitoring of the heated tissue improves the efficacy and safety of the treatment. A temperature-sensitive acoustic parameter is required for ultrasound-based thermometry. In this paper the amplitude and the energy of the acoustic harmonics of the ultrasound backscattered signal are proposed as suitable parameters for noninvasive ultrasound thermometry. A commercial high frequency ultrasound imaging system was used to generate and detect acoustic harmonics in tissue-mimicking gel phantoms and ex vivo bovine muscle tissues. The pressure amplitude and the energy content of the backscattered fundamental frequency (p1 and E1), the second (p2 and E2) and the third (p3 and E3) harmonics were detected in pulse-echo mode. Temperature was increased from 26° to 46 °C uniformly through both samples. The amplitude and the energy content of the harmonics and their ratio were measured and analysed as a function of temperature. The average p1, p2 and p3 increased by 69%, 100% and 283%, respectively as the temperature was elevated from 26° to 46 °C in tissue samples. In the same experiment the average E1, E2 and E3 increased by 163%, 281% and 2257%, respectively. A similar trend was observed in tissue-mimicking gel phantoms. The findings suggest that the harmonics generated due to nonlinear ultrasound beam propagation are highly sensitive to temperature and could potentially be used for noninvasive ultrasound tissue thermometry.
Study on concentration nonlinearity of interacting acoustic flows in cadmium sulfide and tellurium
International Nuclear Information System (INIS)
Ilisavskij, Yu.V.; Kulakova, L.A.; Yakhkind, Eh.Z.
1976-01-01
The ratio of an one-mode (self-action of an external monochromatic sound wave) and a many-mode (interaction of an external wave with crystal thermal phonons) concentration nonlinearity has been experimentally investigated on sound amplification in cadmium sulphide and tellurium. It has been shown that in a strong piezoelectric the main part in the nonlinear limitation of the sound amplification in a drift field is played by the wave interaction, i.e., the transfer of the sound wave energy into the crystal sound modes starts before the nonlinear self-action of a wave. In Te characterized by a large value of the electromechanical coupling constant value at the sound frequency of about 250 MHz the threshold of many-mode nonlinearity is achieved in fields much below the critical one, and corresponds to the sound intensity as low as 10 -7 W/cm 2 , as compared with 10 -2 W/cm 2 -the threshold of the one-mode nonlinearity
Aerodynamic and Nonlinear Dynamic Acoustic Analysis of Tension Asymmetry in Excised Canine Larynges
Devine, Erin E.; Bulleit, Erin E.; Hoffman, Matthew R.; McCulloch, Timothy M.; Jiang, Jack J.
2012-01-01
Purpose: To model tension asymmetry caused by superior laryngeal nerve paralysis (SLNP) in excised larynges and apply perturbation, nonlinear dynamic, and aerodynamic analyses. Method: SLNP was modeled in 8 excised larynges using sutures and weights to mimic cricothyroid (CT) muscle function. Weights were removed from one side to create tension…
Karkar , Sami; Vergez , Christophe; Cochelin , Bruno
2012-01-01
International audience; We propose a new approach based on numerical continuation and bifurcation analysis for the study of physical models of instruments that produce self- sustained oscillation. Numerical continuation consists in following how a given solution of a set of equations is modified when one (or several) parameter of these equations are allowed to vary. Several physical models (clarinet, saxophone, and violin) are formulated as nonlinear dynamical systems, whose periodic solution...
1987-07-01
fields (see also Chapter 4 of Ref. 22). Like our investigation, theirs is based on the Khokhlov-Zabolotskaya-Kuznetsov ( KZK ) equa- tion [23,24...25,26], also based on the KZK e(iualiou, is limited to weakly nonlinear systems. However, the practical case of a focused circular source with gain of...iment. The demonstrated abihty of the KZK equation to accurately model focused sound fields from reahstic sources [i.e., having abrupt edges and
Nonlinear acoustic waves in the viscous thermosphere and ionosphere above earthquake
Czech Academy of Sciences Publication Activity Database
Chum, Jaroslav; Cabrera, M. A.; Mošna, Zbyšek; Fagre, M.; Baše, Jiří; Fišer, Jiří
2016-01-01
Roč. 121, č. 12 (2016), s. 12126-12137 ISSN 2169-9380 R&D Projects: GA ČR(CZ) GC15-07281J Institutional support: RVO:68378289 Keywords : infrasound * seismic waves * ionosphere * nonlinear wave propagation * viscosity * dissipation * remote sensing Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.733, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2016JA023450/full
Response to a pure tone in a nonlinear mechanical-electrical-acoustical model of the cochlea.
Meaud, Julien; Grosh, Karl
2012-03-21
In this article, a nonlinear mathematical model is developed based on the physiology of the cochlea of the guinea pig. The three-dimensional intracochlear fluid dynamics are coupled to a micromechanical model of the organ of Corti and to electrical potentials in the cochlear ducts and outer hair cells (OHC). OHC somatic electromotility is modeled by linearized piezoelectric relations whereas the OHC hair-bundle mechanoelectrical transduction current is modeled as a nonlinear function of the hair-bundle deflection. The steady-state response of the cochlea to a single tone is simulated in the frequency domain using an alternating frequency time scheme. Compressive nonlinearity, harmonic distortion, and DC shift on the basilar membrane (BM), tectorial membrane (TM), and OHC potentials are predicted using a single set of parameters. The predictions of the model are verified by comparing simulations to available in vivo experimental data for basal cochlear mechanics. In particular, the model predicts more amplification on the reticular lamina (RL) side of the cochlear partition than on the BM, which replicates recent measurements. Moreover, small harmonic distortion and DC shifts are predicted on the BM, whereas more significant harmonic distortion and DC shifts are predicted in the RL and TM displacements and in the OHC potentials. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Cavaro, M.
2010-11-01
The SFR system chosen (Sodium Fast Reactor: fast neutron reactors cooled by liquid sodium) by France led to a fourth-generation prototype named ASTRID. The development of this kind of reactors presents several challenges, particularly in terms of improving the safety and monitoring operation. This involves, among other things, characterization of the bubbles presence in liquid sodium. The characterization of the bubbles presence is the subject of this thesis. It involves the determination of void fraction (gas volume fraction) and histogram of the radii of bubbles. The bibliographic work done has shown that linear acoustic techniques for the characterization of bubble clouds are inadequate to achieve this. However promising leads have been identified by studying nonlinear acoustic techniques. This last idea has therefore been explored. An experimental water bench for the generation and optical control of micro-bubbles cloud allowed us to validate finely the reconstruction of histograms of radii through a technique of nonlinear mixing of a high frequency with a low frequency. The potential of the mixing of two high frequencies, more interesting for the industrial point of view has also been demonstrated. Finally, the bases of the transposition of an original technique of nonlinear resonance spectroscopy applied to a bubbles cloud were explored through the introduction of acoustic resonators. The results offer many interesting opportunities, both in terms of industrial applications and for more fundamental understanding of non-linear behavior of a bubble excited by multiple frequencies and of bubbles clouds excited at low frequency. (author)
Kinetic treatment of nonlinear ion-acoustic waves in multi-ion plasma
Ahmad, Zulfiqar; Ahmad, Mushtaq; Qamar, A.
2017-09-01
By applying the kinetic theory of the Valsove-Poisson model and the reductive perturbation technique, a Korteweg-de Vries (KdV) equation is derived for small but finite amplitude ion acoustic waves in multi-ion plasma composed of positive and negative ions along with the fraction of electrons. A correspondent equation is also derived from the basic set of fluid equations of adiabatic ions and isothermal electrons. Both kinetic and fluid KdV equations are stationary solved with different nature of coefficients. Their differences are discussed both analytically and numerically. The criteria of the fluid approach as a limiting case of kinetic theory are also discussed. The presence of negative ion makes some modification in the solitary structure that has also been discussed with its implication at the laboratory level.
Directory of Open Access Journals (Sweden)
Maxim Goryachev
2018-04-01
Full Text Available A quartz Bulk Acoustic Wave resonator is designed to coherently trap phonons in such a way that they are well confined and immune to suspension losses so they exhibit extremely high acoustic Q-factors at low temperature, with Q × f products of order 10 18 Hz. In this work we couple such a resonator to a Superconducting Quantum Interference Device (SQUID amplifier and investigate effects in the strong signal regime. Both parallel and series connection topologies of the system are investigated. The study reveals significant non-Duffing response that is associated with the nonlinear characteristics of Josephson junctions. The nonlinearity provides quasi-periodic structure of the spectrum in both incident power and frequency. The result gives an insight into the open loop behaviour of a future Cryogenic Quartz Oscillator in the strong signal regime.
Jiménez, Noé; Camarena, Francisco; Redondo, Javier; Sánchez-Morcillo, Víctor; Konofagou, Elisa E.
2015-10-01
We report a numerical method for solving the constitutive relations of nonlinear acoustics, where multiple relaxation processes are included in a generalized formulation that allows the time-domain numerical solution by an explicit finite differences scheme. Thus, the proposed physical model overcomes the limitations of the one-way Khokhlov-Zabolotskaya-Kuznetsov (KZK) type models and, due to the Lagrangian density is implicitly included in the calculation, the proposed method also overcomes the limitations of Westervelt equation in complex configurations for medical ultrasound. In order to model frequency power law attenuation and dispersion, such as observed in biological media, the relaxation parameters are fitted to both exact frequency power law attenuation/dispersion media and also empirically measured attenuation of a variety of tissues that does not fit an exact power law. Finally, a computational technique based on artificial relaxation is included to correct the non-negligible numerical dispersion of the finite difference scheme, and, on the other hand, improve stability trough artificial attenuation when shock waves are present. This technique avoids the use of high-order finite-differences schemes leading to fast calculations. The present algorithm is especially suited for practical configuration where spatial discontinuities are present in the domain (e.g. axisymmetric domains or zero normal velocity boundary conditions in general). The accuracy of the method is discussed by comparing the proposed simulation solutions to one dimensional analytical and k-space numerical solutions.
Energy Technology Data Exchange (ETDEWEB)
Stepinski, Tadeusz (ed.); Lingvall, Fredrik; Wennerstroem, Erik; Ping Wu [Uppsala Univ., Dept. of Materials Science (Sweden). Signals and Systems
2004-01-01
This report contains results concerning advanced ultrasound for the inspection of copper canisters for spent nuclear fuel obtained at Signals and Systems, Uppsala University in years 2002/2003. After a short introduction a review of the NDE techniques that have been applied to the assessment of friction stir welds (FSW) is presented. The review is based on the results reported by the specialists from the USA, mostly from the aerospace industry. A separate chapter is devoted to the extended experimental and theoretical research concerning potential of nonlinear waves in NDE applications. Further studies concerning nonlinear propagation of acoustic and elastic waves (classical nonlinearity) are reported. Also a preliminary investigation of the nonlinear ultrasonic detection of contacts and interfaces (non-classical nonlinearity) is included. Report on the continuation of previous work concerning computer simulation of nonlinear propagations of ultrasonic beams in water and in immersed solids is also presented. Finally, results of an investigation concerning a new method of synthetic aperture imaging (SAI) and its comparison to the traditional phased array (PA) imaging and to the synthetic aperture focusing technique (SAFT) are presented. A new spatial-temporal filtering method is presented that is a generalization of the previously proposed filter. Spatial resolution of the proposed method is investigated and compared experimentally to that of classical SAFT and PA imaging. Performance of the proposed method for flat targets is also investigated.
International Nuclear Information System (INIS)
Stepinski, Tadeusz; Lingvall, Fredrik; Wennerstroem, Erik; Ping Wu
2004-01-01
This report contains results concerning advanced ultrasound for the inspection of copper canisters for spent nuclear fuel obtained at Signals and Systems, Uppsala University in years 2002/2003. After a short introduction a review of the NDE techniques that have been applied to the assessment of friction stir welds (FSW) is presented. The review is based on the results reported by the specialists from the USA, mostly from the aerospace industry. A separate chapter is devoted to the extended experimental and theoretical research concerning potential of nonlinear waves in NDE applications. Further studies concerning nonlinear propagation of acoustic and elastic waves (classical nonlinearity) are reported. Also a preliminary investigation of the nonlinear ultrasonic detection of contacts and interfaces (non-classical nonlinearity) is included. Report on the continuation of previous work concerning computer simulation of nonlinear propagations of ultrasonic beams in water and in immersed solids is also presented. Finally, results of an investigation concerning a new method of synthetic aperture imaging (SAI) and its comparison to the traditional phased array (PA) imaging and to the synthetic aperture focusing technique (SAFT) are presented. A new spatial-temporal filtering method is presented that is a generalization of the previously proposed filter. Spatial resolution of the proposed method is investigated and compared experimentally to that of classical SAFT and PA imaging. Performance of the proposed method for flat targets is also investigated
International Nuclear Information System (INIS)
Emamuddin, M.; Yasmin, S.; Mamun, A. A.
2013-01-01
The nonlinear propagation of dust-acoustic waves in a dusty plasma whose constituents are negatively charged dust, Maxwellian ions with two distinct temperatures, and electrons following q-nonextensive distribution, is investigated by deriving a number of nonlinear equations, namely, the Korteweg-de-Vries (K-dV), the modified Korteweg-de-Vries (mK-dV), and the Gardner equations. The basic characteristics of the hump (positive potential) and dip (negative potential) shaped dust-acoustic (DA) Gardner solitons are found to exist beyond the K-dV limit. The effects of two temperature ions and electron nonextensivity on the basic features of DA K-dV, mK-dV, and Gardner solitons are also examined. It has been observed that the DA Gardner solitons exhibit negative (positive) solitons for q c (q>q c ) (where q c is the critical value of the nonextensive parameter q). The implications of our results in understanding the localized nonlinear electrostatic perturbations existing in stellar polytropes, quark-gluon plasma, protoneutron stars, etc. (where ions with different temperatures and nonextensive electrons exist) are also briefly addressed.
Energy Technology Data Exchange (ETDEWEB)
Lissenden, Cliff [Pennsylvania State Univ., State College, PA (United States); Hassan, Tasnin [North Carolina State Univ., Raleigh, NC (United States); Rangari, Vijaya [Tuskegee Univ., Tuskegee, AL (United States)
2014-10-30
The research built upon a prior investigation to develop a unified constitutive model for design-by-analysis of the intermediate heat exchanger (IHX) for a very high temperature reactor (VHTR) design of next generation nuclear plants (NGNPs). Model development requires a set of failure data from complex mechanical experiments to characterize the material behavior. Therefore uniaxial and multiaxial creep-fatigue and creep-ratcheting tests were conducted on the nickel-base Alloy 617 at 850 and 950°C. The time dependence of material behavior, and the interaction of time dependent behavior (e.g., creep) with ratcheting, which is an increase in the cyclic mean strain under load-controlled cycling, are major concerns for NGNP design. This research project aimed at characterizing the microstructure evolution mechanisms activated in Alloy 617 by mechanical loading and dwell times at elevated temperature. The acoustic harmonic generation method was researched for microstructural characterization. It is a nonlinear acoustics method with excellent potential for nondestructive evaluation, and even online continuous monitoring once high temperature sensors become available. It is unique because it has the ability to quantitatively characterize microstructural features well before macroscale defects (e.g., cracks) form. The nonlinear acoustics beta parameter was shown to correlate with microstructural evolution using a systematic approach to handle the complexity of multiaxial creep-fatigue and creep-ratcheting deformation. Mechanical testing was conducted to provide a full spectrum of data for: thermal aging, tensile creep, uniaxial fatigue, uniaxial creep-fatigue, uniaxial creep-ratcheting, multiaxial creep-fatigue, and multiaxial creep-ratcheting. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Optical Microscopy were conducted to correlate the beta parameter with individual microstructure mechanisms. We researched
International Nuclear Information System (INIS)
Lissenden, Cliff; Hassan, Tasnin; Rangari, Vijaya
2014-01-01
The research built upon a prior investigation to develop a unified constitutive model for design-@by-@analysis of the intermediate heat exchanger (IHX) for a very high temperature reactor (VHTR) design of next generation nuclear plants (NGNPs). Model development requires a set of failure data from complex mechanical experiments to characterize the material behavior. Therefore uniaxial and multiaxial creep-@fatigue and creep-@ratcheting tests were conducted on the nickel base Alloy 617 at 850 and 950°C. The time dependence of material behavior, and the interaction of time dependent behavior (e.g., creep) with ratcheting, which is an increase in the cyclic mean strain under load-@controlled cycling, are major concerns for NGNP design. This research project aimed at characterizing the microstructure evolution mechanisms activated in Alloy 617 by mechanical loading and dwell times at elevated temperature. The acoustic harmonic generation method was researched for microstructural characterization. It is a nonlinear acoustics method with excellent potential for nondestructive evaluation, and even online continuous monitoring once high temperature sensors become available. It is unique because it has the ability to quantitatively characterize microstructural features well before macroscale defects (e.g., cracks) form. The nonlinear acoustics beta parameter was shown to correlate with microstructural evolution using a systematic approach to handle the complexity of multiaxial creep-@fatigue and creep-@ratcheting deformation. Mechanical testing was conducted to provide a full spectrum of data for: thermal aging, tensile creep, uniaxial fatigue, uniaxial creep-@fatigue, uniaxial creep-ratcheting, multiaxial creep-fatigue, and multiaxial creep-@ratcheting. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Optical Microscopy were conducted to correlate the beta parameter with individual microstructure mechanisms. We researched application of the
International Nuclear Information System (INIS)
Kumar Samanta, Utpal; Saha, Asit; Chatterjee, Prasanta
2013-01-01
Bifurcations of nonlinear propagation of ion acoustic waves (IAWs) in a magnetized plasma whose constituents are cold ions and kappa distributed electron are investigated using a two component plasma model. The standard reductive perturbation technique is used to derive the Zakharov-Kuznetsov (ZK) equation for IAWs. By using the bifurcation theory of planar dynamical systems to this ZK equation, the existence of solitary wave solutions and periodic travelling wave solutions is established. All exact explicit solutions of these travelling waves are determined. The results may have relevance in dense space plasmas
Acoustic source for generating an acoustic beam
Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian
2016-05-31
An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.
Colosi, John A
2008-09-01
While many results have been intuited from numerical simulation studies, the precise connections between shallow-water acoustic variability and the space-time scales of nonlinear internal waves (NLIWs) as well as the background environmental conditions have not been clearly established analytically. Two-dimensional coupled mode propagation through NLIWs is examined using a perturbation series solution in which each order n is associated with nth-order multiple scattering. Importantly, the perturbation solution gives resonance conditions that pick out specific NLIW scales that cause coupling, and seabed attenuation is demonstrated to broaden these resonances, fundamentally changing the coupling behavior at low frequency. Sound-speed inhomogeneities caused by internal solitary waves (ISWs) are primarily considered and the dependence of mode coupling on ISW amplitude, range width, depth structure, location relative to the source, and packet characteristics are delineated as a function of acoustic frequency. In addition, it is seen that significant energy transfer to modes with initially low or zero energy involves at least a second order scattering process. Under moderate scattering conditions, comparisons of first order, single scattering theoretical predictions to direct numerical simulation demonstrate the accuracy of the approach for acoustic frequencies upto 400 Hz and for single as well as multiple ISW wave packets.
National Research Council Canada - National Science Library
Reeves, Justin M
2008-01-01
...) was conducted from 13 - 15 April 2005 on the continental shelf in the northeast portion of the South China Sea to study the effects of nonlinear internal waves on the transmission of a 400-Hz signal...
Falvo, Cyril
2018-02-01
The theory of linear and non-linear infrared response of vibrational Holstein polarons in one-dimensional lattices is presented in order to identify the spectral signatures of self-trapping phenomena. Using a canonical transformation, the optical response is computed from the small polaron point of view which is valid in the anti-adiabatic limit. Two types of phonon baths are considered: optical phonons and acoustical phonons, and simple expressions are derived for the infrared response. It is shown that for the case of optical phonons, the linear response can directly probe the polaron density of states. The model is used to interpret the experimental spectrum of crystalline acetanilide in the C=O range. For the case of acoustical phonons, it is shown that two bound states can be observed in the two-dimensional infrared spectrum at low temperature. At high temperature, analysis of the time-dependence of the two-dimensional infrared spectrum indicates that bath mediated correlations slow down spectral diffusion. The model is used to interpret the experimental linear-spectroscopy of model α-helix and β-sheet polypeptides. This work shows that the Davydov Hamiltonian cannot explain the observations in the NH stretching range.
Directory of Open Access Journals (Sweden)
S. A. El-Wakil
2012-01-01
Full Text Available The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV equation for small- but finite-amplitude electrostatic ion-acoustic waves in weakly relativistic plasma consisting of warm ions and isothermal electrons. An algebraic method with computerized symbolic computation is applied in obtaining a series of exact solutions of the KdV equation. Numerical studies have been made using plasma parameters which reveal different solutions, that is, bell-shaped solitary pulses, rational pulses, and solutions with singularity at finite points, which called “blowup” solutions in addition to the propagation of an explosive pulses. The weakly relativistic effect is found to significantly change the basic properties (namely, the amplitude and the width of the ion-acoustic waves. The result of the present investigation may be applicable to some plasma environments, such as ionosphere region.
Energy Technology Data Exchange (ETDEWEB)
Perelomova, Anna [Gdansk University of Technology, Faculty of Applied Physics and Mathematics, ul. Narutowicza 11/12, 80-952 Gdansk (Poland)]. E-mail: anpe@mif.pg.gda.pl
2006-08-28
The equation of energy balance is subdivided into two dynamics equations, one describing evolution of the dominative sound, and the second one responsible for acoustic heating. The first one is the famous KZK equation, and the second one is a novel equation governing acoustic heating. The novel dynamic equation considers both periodic and non-periodic sound. Quasi-plane geometry of flow is supposed. Subdividing is provided on the base of specific links of every mode. Media with arbitrary thermic T(p,{rho}) and caloric e(p,{rho}) equations of state are considered. Individual roles of thermal conductivity and viscosity in the heating induced by aperiodic sound in the ideal gases and media different from ideal gases are discussed.
Perelomova, Anna
2006-08-01
The equation of energy balance is subdivided into two dynamics equations, one describing evolution of the dominative sound, and the second one responsible for acoustic heating. The first one is the famous KZK equation, and the second one is a novel equation governing acoustic heating. The novel dynamic equation considers both periodic and non-periodic sound. Quasi-plane geometry of flow is supposed. Subdividing is provided on the base of specific links of every mode. Media with arbitrary thermic T(p,ρ) and caloric e(p,ρ) equations of state are considered. Individual roles of thermal conductivity and viscosity in the heating induced by aperiodic sound in the ideal gases and media different from ideal gases are discussed.
International Nuclear Information System (INIS)
Perelomova, Anna
2006-01-01
The equation of energy balance is subdivided into two dynamics equations, one describing evolution of the dominative sound, and the second one responsible for acoustic heating. The first one is the famous KZK equation, and the second one is a novel equation governing acoustic heating. The novel dynamic equation considers both periodic and non-periodic sound. Quasi-plane geometry of flow is supposed. Subdividing is provided on the base of specific links of every mode. Media with arbitrary thermic T(p,ρ) and caloric e(p,ρ) equations of state are considered. Individual roles of thermal conductivity and viscosity in the heating induced by aperiodic sound in the ideal gases and media different from ideal gases are discussed
Vu, Cung; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher; Johnson, Paul A.; Guyer, Robert; TenCate, James A.; Le Bas, Pierre-Yves
2013-01-01
In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed. In some aspects, the method includes arranging a first source in the borehole and generating a steered beam of elastic energy at a first frequency; arranging a second source in the borehole and generating a steerable beam of elastic energy at a second frequency, such that the steerable beam at the first frequency and the steerable beam at the second frequency intercept at a location away from the borehole; receiving at the borehole by a sensor a third elastic wave, created by a three wave mixing process, with a frequency equal to a difference between the first and second frequencies and a direction of propagation towards the borehole; determining a location of a three wave mixing region based on the arrangement of the first and second sources and on properties of the third wave signal; and creating three-dimensional images of the non-linear properties using data recorded by repeating the generating, receiving and determining at a plurality of azimuths, inclinations and longitudinal locations within the borehole. The method is additionally used to generate three dimensional images of the ratio of compressional to shear acoustic velocity of the same volume surrounding the borehole.
Shih, C. C.
1973-01-01
In order to establish a foundation of scaling laws for the highly nonlinear waves associated with the launch vehicle, the basic knowledge of the relationships among the paramaters pertinent to the energy dissipation process associated with the propagation of nonlinear pressure waves in thermoviscous media is required. The problem of interest is to experimentally investigate the temporal and spacial velocity profiles of fluid flow in a 3-inch open-end pipe of various lengths, produced by the propagation of nonlinear pressure waves for various diaphragm burst pressures of a pressure wave generator. As a result, temporal and spacial characteristics of wave propagation for a parametric set of nonlinear pressure waves in the pipe containing air under atmospheric conditions were determined. Velocity measurements at five sections along the pipes of up to 210 ft. in length were made with hot-film anemometers for five pressure waves produced by a piston. The piston was derived with diaphragm burst pressures at 20, 40, 60, 80 and 100 psi in the driver chamber of the pressure wave generator.
Zorębski, Edward; Zorębski, Michał
2014-01-01
The so-called Beyer nonlinearity parameter B/A is calculated for 1,2- and 1,3-propanediol, 1,2-, 1,3-, and 1,4-butanediol, as well as 2-methyl-2,4-pentanediol by means of a thermodynamic method. The calculations are made for temperatures from (293.15 to 318.15) K and pressures up to 100 MPa. The decrease in B/A values with the increasing pressure is observed. In the case of 1,3-butanediol, the results are compared with corresponding literature data. The consistency is very satisfactory. A simple relationship between the internal pressure and B/A nonlinearity parameter has also been studied. Copyright © 2013 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Rizzato, F.B.
1992-01-01
A nonlinear emission mechanism of electromagnetic waves at the fundamental plasma frequency has been examined. This mechanism is based on the electromagnetic oscillating two-stream instability driven by two oppositely propagating Langmuir waves. The excitation of the electromagnetic oscillating two-stream instability is due to nonlinear wave-wave coupling involving Langmuir waves, low-frequency density waves and electromagnetic waves. The Chian and Alves model is improved using the generalized Zakharov equations. Attention is directed toward the influence of induced low-frequency and Langmuir waves on the properties of the electromagnetic oscillating two-stream instability. Presumably, the properties derived in the present context may be relevant to both space and laboratory plasmas. (author)
International Nuclear Information System (INIS)
Singh, Kh.I.; Das, G.C.
1993-01-01
Soliton propagations are studied in a relativistic multicomponent ion-beam plasma through the derivation of Korteweg-deVries (K-dV) and modified K-dV (mK-dV) equations. A generalization of the mK-dV equation involving higher order nonlinearities gives a transitive link between the K-dV and mK-dV equations for isothermal plasma, and the validity of this generalized equation throughout the whole range of negative ion concentrations is investigated through the derivation of Sagdeev potential. Parallel discussion of various K-dV solitons enlightening the experimental implications is also made. (author). 22 refs
International Nuclear Information System (INIS)
Zahran, M.A.; El-Shewy, E.K.
2008-01-01
The nonlinear properties of solitary wave structures are reported in an unmagnetized collisionless plasma comprising of cold relativistic electron fluid, Maxwellian hot electrons, relativistic electron beam, and stationary ions. The Korteweg--de Vries (KdV) equation has been derived using a reductive perturbation theory. As the wave amplitude increases, the width and velocity of the soliton deviate from the prediction of the KdV equation i.e. the breakdown of the KdV approximation. On the other hand, to overcome this weakness we extend our analysis to obtain the KdV equation with fifth-order dispersion term. The solution of the resulting equation has been obtained
International Nuclear Information System (INIS)
Douvropoulos, Theodosios G
2012-01-01
An approximate formula for the period of pendulum motion beyond the small amplitude regime is obtained based on physical arguments. Two different schemes of different accuracy are developed: in the first less accurate scheme, emphasis is given on the non-quadratic form of the potential in connection to isochronism, and a specific form of a generic formula that is met in many previous works is produced, while the second and main result contains the Struve function which is further approximated by a simple sinusoidal expression based on its maximum value. The accuracy of the final formula gives a relative error of less than 0.2% for angles up to 140°. In addition, a simple relation between the Struve function and the complete elliptic integral of the first kind is produced, since they both constitute solutions of the pendulum period. This relation makes it possible for someone to connect different areas in physics and solve a difficult task by comparison with another much more simple one. As an example, a connection between the pendulum period and the acoustical radiation impedance is proposed through impedance matching and some interesting relations are produced. This paper is intended for undergraduate students to be useful for analysing pendulum experiments in introductory physics labs and it is also believed to offer valuable insight into some properties of the simple pendulum in undergraduate courses on general physics. (paper)
Electrostatic ion acoustic waves
International Nuclear Information System (INIS)
Hasegawa, A.
1983-01-01
In this paper, certain aspects of plasma physics are illustrated through a study of electrostatic ion acoustic waves. The paper consists of three Sections. Section II deals with linear properties of the ion acoustic wave including derivation of the dispersions relation with the effect of Landau damping and of an ambient magnetic field. The section also introduces the excitation processes of the ion acoustic wave due to an electron drift or to a stimulated Brillouin scattering. The nonlinear properties are introduced in Section III and IV. In Section III, incoherent nonlinear effects such as quasilinear and mode-coupling saturations of the instability are discussed. The coherent nonlinear effects such as the generation of ion acoustic solitons, shocks and weak double layers are presented in Section IV. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Stepinski, Tadeusz (ed.); Ping Wu; Wennerstroem, Erik [Uppsala Univ. (Sweden). Signals and Systems
2004-09-01
This report contains the research results concerning advanced ultrasound for the inspection of copper canisters for spent nuclear fuel obtained at Signals and Systems, Uppsala University in years 2003/2004. After a short introduction a review of beam forming fundamentals required for proper understanding phased array operation is included. The factors that determine lateral resolution during ultrasonic imaging of flaws in solids are analyzed and results of simulations modelling contact inspection of copper are presented. In the second chapter an improved synthetic aperture imaging (SAI) technique is introduced. The proposed SAI technique is characterized by an enhanced lateral resolution compared with the previously proposed extended synthetic aperture focusing technique (ESAFT). The enhancement of imaging performance is achieved due to more realistic assumption concerning the probability density function of scatterers in the region of interest. The proposed technique takes the form of a two-step algorithm using the result obtained in the first step as a prior for the second step. Final chapter contains summary of our recent experimental and theoretical research on nonlinear ultrasonics of unbounded interfaces. A new theoretical model for rough interfaces is developed, and the experimental results from the copper specimens that mimic contact cracks of different types are presented. Derivation of the theory and selected measurement results are given in appendix.
Springer handbook of acoustics
2014-01-01
Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and electronics. The Springer Handbook of Acoustics is also in his 2nd edition an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents. This new edition of the Handbook features over 11 revised and expanded chapters, new illustrations, and 2 new chapters covering microphone arrays and acoustic emission. Updated chapters contain the latest research and applications in, e.g. sound propagation in the atmosphere, nonlinear acoustics in fluids, building and concert hall acoustics, signal processing, psychoacoustics, computer music, animal bioacousics, sound intensity, modal acoustics as well as new chapters on microphone arrays an...
Eliminating transducer distortion in acoustic measurements
DEFF Research Database (Denmark)
Agerkvist, Finn T.; Torras Rosell, Antoni; McWalter, Richard Ian
2014-01-01
This paper investigates the in uence of nonlinear components that contaminate the linear response of acoustic transducer, and presents a method for eliminating the in uence of nonlinearities in acoustic measurements. The method is evaluated on simulated as well as experimental data, and is shown...
Support minimized inversion of acoustic and elastic wave scattering
International Nuclear Information System (INIS)
Safaeinili, A.
1994-01-01
This report discusses the following topics on support minimized inversion of acoustic and elastic wave scattering: Minimum support inversion; forward modelling of elastodynamic wave scattering; minimum support linearized acoustic inversion; support minimized nonlinear acoustic inversion without absolute phase; and support minimized nonlinear elastic inversion
International Nuclear Information System (INIS)
Senin, H.B.; Sidek, H.A.A.; Saunders, G.A.
1994-01-01
From measurements of changes in transit time of 10 MHz of ultrasonic wave as a function of temperature and hydrostatic pressure, the linear and non-linear acoustic properties of the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses with compositions near to that corresponding to the metaphosphate have been determined. For each glass the second order elastic stiffness tensor components C sub ijs (SOEC) continue to increase down to 10K in a manner consistent with phonons interactions with two level systems. Measurements of the effects of hydrostatic pressure on the ultrasonic wave velocities have been used to determine the hydrostatic pressure derivatives (dC sub ij/dP) sub T,P=0 of the SOEC and (dB0 sup s)/dP) sub T,P=0 of the bulk modulus B0 sup s at room temperature (293K). For the ternary (La sub 2 O sub 3) sub x (Sm sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses, (dC sub 11/dP), (dC sub 44/dP), and (dBo/dP), are small but positives; these glasses stiffen under pressure. The elastic behaviour of these ternary glasses lies intermediate between those of (Sm sub 2 O sub 3)(P sub 2 O sub 5) sub (1-x) and (La sub 2 O sub 3) sub y (P sub 2 O sub 5) sub (1-x-y) glasses. Replacement of the Sm sup 3+ by La sup 3+ in the ternary phosphate glasses negates the acoustic mode softening. Possible sources of the different effects of La sub 3+ and Sm sub 3+ modifiers on the nonlinear acoustic properties of metaphosphate glasses are discussed
Linear and Nonlinear Electrostatic Waves in Unmagnetized Dusty Plasmas
International Nuclear Information System (INIS)
Mamun, A. A.; Shukla, P. K.
2010-01-01
A rigorous and systematic theoretical study has been made of linear and nonlinear electrostatic waves propagating in unmagnetized dusty plasmas. The basic features of linear and nonlinear electrostatic waves (particularly, dust-ion-acoustic and dust-acoustic waves) for different space and laboratory dusty plasma conditions are described. The experimental observations of such linear and nonlinear features of dust-ion-acoustic and dust-acoustic waves are briefly discussed.
Sonic excitation by means of ultrasound; an experimental illustration of acoustic radiation forces
Roozen, N.B.; Nuij, P.W.J.M.
2011-01-01
Ultrasonic acoustic waves are known to induce a vibration of particles around an equilibrium position. However, for large acoustic amplitudes, due to non-linear acoustic effects, a rectified, net acoustic radiation force can occur. Experimental work is performed in which the non-linear behavior is
Ion-acoustic plasma turbulence
International Nuclear Information System (INIS)
Bychenkov, V.Y.; Silin, V.P.
1982-01-01
A theory is developed of the nonlinear state that is established in a plasma as a result of development of ion-acoustic instability. Account is taken simultaneously of the linear induced scattering of the waves by the ions and of the quasilinear relaxation of the electrons by the ion-acoustic pulsations. The distribution of the ion-acoustic turbulence in frequency and in angle is obtained. An Ohm's law is established and expressions are obtained for the electronic heat flux and for the relaxation time of the electron temperature in a turbulent plasma. Anomalously large absorption and scattering of the electromagnetic waves by the ion-acoustic pulsations is predicted
National Research Council Canada - National Science Library
Long, Marshall
2014-01-01
.... Beginning with a brief history, it reviews the fundamentals of acoustics, human perception and reaction to sound, acoustic noise measurements, noise metrics, and environmental noise characterization...
International Nuclear Information System (INIS)
Nichols, R.W.
1976-01-01
The volume contains six papers which together provide an overall review of the inspection technique known as acoustic emission or stress wave emission. The titles are: a welder's introduction to acoustic emission technology; use of acoustic emission for detection of defects as they arise during fabrication; examples of laboratory application and assessment of acoustic emission in the United Kingdom; (Part I: acoustic emission behaviour of low alloy steels; Part II: fatigue crack assessment from proof testing and continuous monitoring); inspection of selected areas of engineering structures by acoustic emission; Japanese experience in laboratory and practical applications of acoustic emission to welded structures; and ASME acoustic emission code status. (U.K.)
Nonlinear Approaches in Engineering Applications
Jazar, Reza
2012-01-01
Nonlinear Approaches in Engineering Applications focuses on nonlinear phenomena that are common in the engineering field. The nonlinear approaches described in this book provide a sound theoretical base and practical tools to design and analyze engineering systems with high efficiency and accuracy and with less energy and downtime. Presented here are nonlinear approaches in areas such as dynamic systems, optimal control and approaches in nonlinear dynamics and acoustics. Coverage encompasses a wide range of applications and fields including mathematical modeling and nonlinear behavior as applied to microresonators, nanotechnologies, nonlinear behavior in soil erosion,nonlinear population dynamics, and optimization in reducing vibration and noise as well as vibration in triple-walled carbon nanotubes. This book also: Provides a complete introduction to nonlinear behavior of systems and the advantages of nonlinearity as a tool for solving engineering problems Includes applications and examples drawn from the el...
PVT Degradation Studies: Acoustic Diagnostics
Energy Technology Data Exchange (ETDEWEB)
Dib, Gerges [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tucker, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, Philip J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2017-04-01
Under certain environmental conditions, polyvinyl toluene (PVT) plastic scintillator has been observed to undergo internal fogging. This document reports on a study of acoustic techniques to determine whether they can provide a diagnostic for the fogging of PVT. Different ultrasound techniques were employed for detecting the level of internal fogging in PVT, including wave velocity measurements, attenuation, nonlinear acoustics, and acoustic microscopy. The results indicate that there are linear relations between the wave velocity and wave attenuation with the level of internal fogging. The effects of fogging on ultrasound wave attenuation is further verified by acoustic microscopy imaging, where regions with fog in the specimen demonstration higher levels of attenuation compared to clear regions. Results from the nonlinear ultrasound measurements were inconclusive due to high sensitivities to transducer coupling and fixture variabilities.
DEFF Research Database (Denmark)
Blauert, Jens
Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....
International Nuclear Information System (INIS)
Shah, Asif; Saeed, R
2011-01-01
The ion-acoustic shock waves are studied in electron-positron-ion plasma. The plasma system is composed of three components, specifically relativistic adiabatic ions, kappa distributed electrons and positrons. The Korteweg-de Vries-Burger equation is derived, solved analytically. The effects of plasma parameters on the shock strength and steepness are investigated. The numerical results are presented graphically for illustration. The results may have importance in non-thermal and relativistic plasmas of pulsar magnetosphere (Arons 2009 Astrophys. Space Sci. Library 357 373; Blasi and Amato arXiv:1007.4745V1 [astro-Ph.HE]).
1993-08-24
T. Blackstock, "Shock wave propagation and shape of the waveform," Conference on Lithotripsy (Extra-Corporeal Shock Wave Applications - Technical and...83, S5 (1988). 0574 0 b4 . D. T. Blackstock, "Physical aspects of lithotripsy ," Paper GG1, 115th Meeting, Acoustical Society of America, Seattle, 16...1991). kAlso supported in part by Grant NAG-1-1204 and University of Southampton , Eng- land. 23 1992 ONR Contract Code 1109 0 . James A. Ten Cate
An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...
Casciaro, Sergio; Demitri, Christian; Conversano, Francesco; Casciaro, Ernesto; Distante, Alessandro
2008-02-01
Native harmonics generated by nonlinear distortion of ultrasound during propagation in a medium may cause misinterpretations in spectral analysis when studying contrast agents. The aim of this paper is to quantitatively evaluate nonlinear propagation effects of diagnostic ultrasound pulses in biological tissues and to assess whether a cellulose-based hydrogel can be a suitable material for tissue mimicking purposes. Hydrogel and pig liver tissue samples of various thicknesses were insonified in a through-transmission set-up, employing 2.25-MHz pulses with different mechanical index (MI) values (range 0.06-0.60). Second harmonic and first harmonic amplitudes were extracted from spectra of received signals and their ratio was then used to compare hydrogel and liver behaviours. Resulting trends are very similar for sample thicknesses up to 8 cm and highlight a significant increase in nonlinearity for MI > 0.3, for both liver and hydrogel. A numerical procedure was also employed to calculate pressure distribution along the beam axis: these theoretical results showed a very good agreement with experimental data in the low pressure range, though failed in predicting the MI threshold. In conclusion, the hydrogel resulted to be a suitable material for manufacturing tissue mimicking phantoms, in particular to study contrast agent behaviour with a "low power approach".
Cylindrical dust acoustic waves with transverse perturbation
International Nuclear Information System (INIS)
Xue Jukui
2003-01-01
The nonlinear dust acoustic waves in dusty plasmas with the combined effects of bounded cylindrical geometry and the transverse perturbation are studied. Using the perturbation method, a cylindrical Kadomtsev-Petviashvili (CKP) equation that describes the dust acoustic waves is deduced for the first time. A particular solution of this CKP equation is also obtained. It is shown that the dust acoustic solitary waves can exist in the CKP equation
Yuldashev, Petr V.; Shmeleva, Svetlana M.; Ilyin, Sergey A.; Sapozhnikov, Oleg A.; Gavrilov, Leonid R.; Khokhlova, Vera A.
2013-04-01
The goal of this study was to investigate theoretically the effects of nonlinear propagation in a high-intensity focused ultrasound (HIFU) field produced by a therapeutic phased array and the resultant heating of tissue behind a rib cage. Three configurations of focusing were simulated: in water, in water with ribs in the beam path and in water with ribs backed by a layer of soft tissue. The Westervelt equation was used to model the nonlinear HIFU field, and a 1 MHz phased array consisting of 254 circular elements was used as a boundary condition to the model. The temperature rise in tissue was modelled using the bioheat equation, and thermally necrosed volumes were calculated using the thermal dose formulation. The shapes of lesions predicted by the modelling were compared with those previously obtained in in vitro experiments at low-power sonications. Intensity levels at the face of the array elements that corresponded to the formation of high-amplitude shock fronts in the focal region were determined as 10 W cm-2 in the free field in water and 40 W cm-2 in the presence of ribs. It was shown that exposures with shocks provided a substantial increase in tissue heating, and its better spatial localization in the main focal region only. The relative effects of overheating ribs and splitting of the focus due to the periodic structure of the ribs were therefore reduced. These results suggest that utilizing nonlinear propagation and shock formation effects can be beneficial for inducing confined HIFU lesions when irradiating through obstructions such as ribs. Design of compact therapeutic arrays to provide maximum power outputs with lower intensity levels at the elements is necessary to achieve shock wave regimes for clinically relevant sonication depths in tissue.
Improvements in Elimination of Loudspeaker Distortion in Acoustic Measurements
DEFF Research Database (Denmark)
Agerkvist, Finn T.; Torras Rosell, Antoni; McWalter, Richard Ian
2015-01-01
This paper investigates the influence of nonlinear components that contaminate the linear response of acoustic transducers, and presents improved methods for eliminating the influence of nonlinearities in acoustic measurements. The method is evaluated with pure sinusoidal signals as well as swept...
Acoustic cloaking and transformation acoustics
International Nuclear Information System (INIS)
Chen Huanyang; Chan, C T
2010-01-01
In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)
Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile
2015-03-01
The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.
Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging
2012-01-01
The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging
Nayak, Rajkishore
2016-01-01
This book highlights the manufacturing and applications of acoustic textiles in various industries. It also includes examples from different industries in which acoustic textiles can be used to absorb noise and help reduce the impact of noise at the workplace. Given the importance of noise reduction in the working environment in several industries, the book offers a valuable guide for companies, educators and researchers involved with acoustic materials.
Acoustic Parametric Array for Identifying Standoff Targets
Hinders, M. K.; Rudd, K. E.
2010-02-01
An integrated simulation method for investigating nonlinear sound beams and 3D acoustic scattering from any combination of complicated objects is presented. A standard finite-difference simulation method is used to model pulsed nonlinear sound propagation from a source to a scattering target via the KZK equation. Then, a parallel 3D acoustic simulation method based on the finite integration technique is used to model the acoustic wave interaction with the target. Any combination of objects and material layers can be placed into the 3D simulation space to study the resulting interaction. Several example simulations are presented to demonstrate the simulation method and 3D visualization techniques. The combined simulation method is validated by comparing experimental and simulation data and a demonstration of how this combined simulation method assisted in the development of a nonlinear acoustic concealed weapons detector is also presented.
Zhen, Hui-Ling; Tian, Bo; Xie, Xi-Yang; Wu, Xiao-Yu; Wen, Xiao-Yong
2018-02-01
On our previous construction [H. L. Zhen et al., Phys. Plasmas 23, 052301 (2016)] of the soliton solutions of a model describing the dynamics of the dust particles in a weakly ionized, collisional dusty plasma comprised of the negatively charged cold dust particles, hot ions, hot electrons, and stationary neutrals in the presence of an external static magnetic field, Ali et al. [Phys. Plasmas 24, 094701 (2017)] have commented that there exists a different form of Eq. (4) from that shown in Zhen et al. [Phys. Plasmas 23, 052301 (2016)] and that certain interesting phenomena with the dust neutral collision frequency ν0>0 are ignored in Zhen et al. [Phys. Plasmas 23, 052301 (2016)]. In this Reply, according to the transformation given by the Ali et al. [Phys. Plasmas 24, 094701 (2017)] comment, we present some one-, two-, and N-soliton solutions which have not been obtained in the Ali et al. [Phys. Plasmas 24, 094701 (2017)] comment. We point out that our previous solutions in Zhen et al. [Phys. Plasmas 23, 052301 (2016)] are still valid because of the similarity between the two dispersion relations of previous solutions in Zhen et al. [Phys. Plasmas 23, 052301 (2016)] and the solutions presented in this Reply. Based on our soliton solutions in this Reply, it is found that the soliton amplitude is inversely related to Zd and B0, but positively related to md and α, where α refers to the coefficient of the nonlinear term, Zd and md are the charge number and mass of a dust particle, respectively, B0 represents the strength of the external static magnetic field. We also find that the two solitons are always in parallel during the propagation.
Damarla, Thyagaraju
2015-01-01
This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code...
National Oceanic and Atmospheric Administration, Department of Commerce — Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B....
Akiyama, Iwaki
2009-01-01
The 29th International Symposium on Acoustical Imaging was held in Shonan Village, Kanagawa, Japan, April 15-18, 2007. This interdisciplinary Symposium has been taking place every two years since 1968 and forms a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. In the course of the years the volumes in the Acoustical Imaging Series have developed and become well-known and appreciated reference works. Offering both a broad perspective on the state-of-the-art in the field as well as an in-depth look at its leading edge research, this Volume 29 in the Series contains again an excellent collection of seventy papers presented in nine major categories: Strain Imaging Biological and Medical Applications Acoustic Microscopy Non-Destructive Evaluation and Industrial Applications Components and Systems Geophysics and Underwater Imaging Physics and Mathematics Medical Image Analysis FDTD method and Other Numerical Simulations Audience Researcher...
Kuttruff, Heinrich; Mommertz, Eckard
The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.
NR-code: Nonlinear reconstruction code
Yu, Yu; Pen, Ue-Li; Zhu, Hong-Ming
2018-04-01
NR-code applies nonlinear reconstruction to the dark matter density field in redshift space and solves for the nonlinear mapping from the initial Lagrangian positions to the final redshift space positions; this reverses the large-scale bulk flows and improves the precision measurement of the baryon acoustic oscillations (BAO) scale.
Fogel, Ronen; Limson, Janice; Seshia, Ashwin A
2016-06-30
Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.
Observation of self-excited acoustic vortices in defect-mediated dust acoustic wave turbulence.
Tsai, Ya-Yi; I, Lin
2014-07-01
Using the self-excited dust acoustic wave as a platform, we demonstrate experimental observation of self-excited fluctuating acoustic vortex pairs with ± 1 topological charges through spontaneous waveform undulation in defect-mediated turbulence for three-dimensional traveling nonlinear longitudinal waves. The acoustic vortex pair has helical waveforms with opposite chirality around the low-density hole filament pair in xyt space (the xy plane is the plane normal to the wave propagation direction). It is generated through ruptures of sequential crest surfaces and reconnections with their trailing ruptured crest surfaces. The initial rupture is originated from the amplitude reduction induced by the formation of the kinked wave crest strip with strong stretching through the undulation instability. Increasing rupture causes the separation of the acoustic vortex pair after generation. A similar reverse process is followed for the acoustic vortex annihilating with the opposite-charged acoustic vortex from the same or another pair generation.
International Nuclear Information System (INIS)
Cornuelle, Bruce D; Worcester, Peter F; Dzieciuch, Matthew A
2008-01-01
Ocean acoustic tomography (OAT) was proposed in 1979 by Walter Munk and Carl Wunsch as an analogue to x-ray computed axial tomography for the oceans. The oceans are opaque to most electromagnetic radiation, but there is a strong acoustic waveguide, and sound can propagate for 10 Mm and more with distinct multiply-refracted ray paths. Transmitting broadband pulses in the ocean leads to a set of impulsive arrivals at the receiver which characterize the impulse response of the sound channel. The peaks observed at the receiver are assumed to represent the arrival of energy traveling along geometric ray paths. These paths can be distinguished by arrival time, and by arrival angle when a vertical array of receivers is available. Changes in ray arrival time can be used to infer changes in ocean structure. Ray travel time measurements have been a mainstay of long-range acoustic measurements, but the strong sensitivity of ray paths to range-dependent sound speed perturbations makes the ray sampling functions uncertain in real cases. In the ray approximation travel times are sensitive to medium changes only along the corresponding eigenrays. Ray theory is an infinite-frequency approximation, and its eikonal equation has nonlinearities not found in the acoustic wave equation. We build on recent seismology results (kernels for body wave arrivals in the earth) to characterize the kernel for converting sound speed change in the ocean to travel time changes using more complete propagation physics. Wave-theoretic finite frequency kernels may show less sensitivity to small-scale sound speed structure.
Nonlinear Acoustic Metamaterials for Sound Attenuation Applications
2011-03-16
elastic guides, which are discretized into Bernoulli -Euler beam elements [29]. We first describe the equations of particles’ motion in the DE model...to 613 N in the curved one [see Fig. 15(b)]. Overall, the area under the force-time curve, which corresponds to the amount of momentum transferred
Ion-acoustic cnoidal waves in a quantum plasma
International Nuclear Information System (INIS)
Mahmood, S.; Haas, F.
2014-01-01
Nonlinear ion-acoustic cnoidal wave structures are studied in an unmagnetized quantum plasma. Using the reductive perturbation method, a Korteweg-de Vries equation is derived for appropriate boundary conditions and nonlinear periodic wave solutions are obtained. The corresponding analytical solution and numerical plots of the ion-acoustic cnoidal waves and solitons in the phase plane are presented using the Sagdeev pseudo-potential approach. The variations in the nonlinear potential of the ion-acoustic cnoidal waves are studied at different values of quantum parameter H e which is the ratio of electron plasmon energy to electron Fermi energy defined for degenerate electrons. It is found that both compressive and rarefactive ion-acoustic cnoidal wave structures are formed depending on the value of the quantum parameter. The dependence of the wavelength and frequency on nonlinear wave amplitude is also presented
International Nuclear Information System (INIS)
Straus, A.; Lopez Pumarega, M.I.; Di Gaetano, J.O.; D'Atellis, C.E.; Ruzzante, J.E.
1990-01-01
This paper is related to our activities on acoustic emission (A.E.). The work is made with different materials: metals and fibre reinforced plastics. At present, acoustic emission transducers are being developed for low and high temperature. A test to detect electrical discharges in electrical transformers was performed. Our experience in industrial tests to detect cracks or failures in tanks or tubes is also described. The use of A.E. for leak detection is considered. Works on pattern recognition of A.E. signals are also being performed. (Author)
Cowan, James
This chapter summarizes and explains key concepts of building acoustics. These issues include the behavior of sound waves in rooms, the most commonly used rating systems for sound and sound control in buildings, the most common noise sources found in buildings, practical noise control methods for these sources, and the specific topic of office acoustics. Common noise issues for multi-dwelling units can be derived from most of the sections of this chapter. Books can be and have been written on each of these topics, so the purpose of this chapter is to summarize this information and provide appropriate resources for further exploration of each topic.
Plasmon band gap generated by intense ion acoustic waves
International Nuclear Information System (INIS)
Son, S.; Ku, S.
2010-01-01
In the presence of an intense ion acoustic wave, the energy-momentum dispersion relation of plasmons is strongly modified to exhibit a band gap structure. The intensity of an ion acoustic wave might be measured from the band gap width. The plasmon band gap can be used to block the nonlinear cascading channel of the Langmuir wave decay.
1993-06-03
propagation and shape of the waveform," Conference on Lithotripsy (Extra-Corporeal Shock Wave Applications - Technical and Clinical Problems), Univer- sity of...Blackstock, "Physical aspects of lithotripsy ," Paper GG1, 115th Meeting, Acoustical Society of America, Seattle, 16-20 May 1988. ABSTRACT: J. Acoust...Am. 90, 2244(A) (1991). kAlso supported in part by Grant NAG-1-1204 and University of Southampton , Eng- land. 49 1992 ONR Contract Code 1109 JS 1. F
International Nuclear Information System (INIS)
Boyd, R.W.
1992-01-01
Nonlinear optics is the study of the interaction of intense laser light with matter. This book is a textbook on nonlinear optics at the level of a beginning graduate student. The intent of the book is to provide an introduction to the field of nonlinear optics that stresses fundamental concepts and that enables the student to go on to perform independent research in this field. This book covers the areas of nonlinear optics, quantum optics, quantum electronics, laser physics, electrooptics, and modern optics
DEFF Research Database (Denmark)
Kreutzfeldt, Jacob
2011-01-01
Under the heading of "Gang i København" a number of initiatives was presented by the Lord Mayer and the Technical and Environmental Mayer of Copenhagen in May 2006. The aim of the initiative, which roughly translates to Lively Copenhagen, was both to make Copenhagen a livelier city in terms of city...... this article outline a few approaches to a theory of acoustic territoriality....
International Nuclear Information System (INIS)
Kittmer, C.A.
1983-03-01
Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed
Bodén, Hans
2012-01-01
This paper discusses the effect of high level multi-tone acoustic excitation on the acoustic properties of perforates and liner samples. It is based on a large experimental study of the nonlinear properties of these types of samples without mean grazing or bias flow. It is known from previous studies that high level acoustic excitation at one frequency will change the acoustic impedance of perforates at other frequencies, thereby changing the boundary condition seen by the acoustic waves. Thi...
Bloembergen, Nicolaas
1996-01-01
Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe
Ocean acoustic tomography - Travel time biases
Spiesberger, J. L.
1985-01-01
The travel times of acoustic rays traced through a climatological sound-speed profile are compared with travel times computed through the same profile containing an eddy field. The accuracy of linearizing the relations between the travel time difference and the sound-speed deviation at long ranges is assessed using calculations made for two different eddy fields measured in the eastern Atlantic. Significant nonlinearities are found in some cases, and the relationships of the values of these nonlinearities to the range between source and receiver, to the anomaly size associated with the eddies, and to the positions of the eddies are studied. An analytical model of the nonlinearities is discussed.
Dust acoustic solitary and shock waves in strongly coupled dusty ...
Indian Academy of Sciences (India)
between nonlinear and dispersion effects can result in the formation of symmetrical solitary waves. Also shock ... et al have studied the effect of nonadiabatic dust charge variation on the nonlinear dust acoustic wave with ..... Figure 5 presents the border between oscillatory- and monotonic-type shock waves as functions of ...
Modeling the SAR Signature of Nonlinear Internal Waves
National Research Council Canada - National Science Library
Lettvin, Ellen E
2008-01-01
Nonlinear Internal Waves are pervasive globally, particularly in coastal waters. The currents and displacements associated with internal waves influence acoustic propagation and underwater navigation, as well as ocean transport and mixing...
... EVENTS DONATE NEWS Home Learn Back Learn about acoustic neuroma AN Facts What is acoustic neuroma? Diagnosing ... Brain Freeze ? READ MORE Read More What is acoustic neuroma? Identifying an AN Learn More Get Info ...
Acoustic properties of perforates under high level multi-tone excitation
Bodén, Hans
2013-01-01
This paper discusses the effect of high level multi-tone acoustic excitation on the acoustic properties of perforates. It is based on a large experimental study of the nonlinear properties of these types of samples without mean grazing or bias flow. Compared to previously published results the present investigation concentrates on the effect of multiple harmonics. It is known from previous studies that high level acoustic excitation at one frequency will change the acoustic impedance of perfo...
Solitary waves on nonlinear elastic rods. I
DEFF Research Database (Denmark)
Sørensen, Mads Peter; Christiansen, Peter Leth; Lomdahl, P. S.
1984-01-01
Acoustic waves on elastic rods with circular cross section are governed by improved Boussinesq equations when transverse motion and nonlinearity in the elastic medium are taken into account. Solitary wave solutions to these equations have been found. The present paper treats the interaction betwe...... nonlinearity. The balance between dispersion and nonlinearity in the equation is investigated.......Acoustic waves on elastic rods with circular cross section are governed by improved Boussinesq equations when transverse motion and nonlinearity in the elastic medium are taken into account. Solitary wave solutions to these equations have been found. The present paper treats the interaction between...... the solitary waves numerically. It is demonstrated that the waves behave almost like solitons in agreement with the fact that the improved Boussinesq equations are nearly integrable. Thus three conservation theorems can be derived from the equations. A new subsonic quasibreather is found in the case of a cubic...
Panel acoustic contribution analysis.
Wu, Sean F; Natarajan, Logesh Kumar
2013-02-01
Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated.
Yoshida, Zensho
2010-01-01
This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl
Nayfeh, Ali Hasan
1995-01-01
Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim
Acoustic and streaming velocity components in a resonant waveguide at high acoustic levels.
Daru, Virginie; Reyt, Ida; Bailliet, Hélène; Weisman, Catherine; Baltean-Carlès, Diana
2017-01-01
Rayleigh streaming is a steady flow generated by the interaction between an acoustic wave and a solid wall, generally assumed to be second order in a Mach number expansion. Acoustic streaming is well known in the case of a stationary plane wave at low amplitude: it has a half-wavelength spatial periodicity and the maximum axial streaming velocity is a quadratic function of the acoustic velocity amplitude at antinode. For higher acoustic levels, additional streaming cells have been observed. Results of laser Doppler velocimetry measurements are here compared to direct numerical simulations. The evolution of axial and radial velocity components for both acoustic and streaming velocities is studied from low to high acoustic amplitudes. Two streaming flow regimes are pointed out, the axial streaming dependency on acoustics going from quadratic to linear. The evolution of streaming flow is different for outer cells and for inner cells. Also, the hypothesis of radial streaming velocity being of second order in a Mach number expansion, is not valid at high amplitudes. The change of regime occurs when the radial streaming velocity amplitude becomes larger than the radial acoustic velocity amplitude, high levels being therefore characterized by nonlinear interaction of the different velocity components.
Drumheller, Douglas S.
2000-01-01
An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.
International Nuclear Information System (INIS)
Swift, G.W.; Martin, R.A.; Radebaugh, R.
1990-01-01
This patent describes an acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effect to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15--60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintain a cooling load of 5 W at 80 K
Palmero, Faustino; Lemos, M; Sánchez-Rey, Bernardo; Casado-Pascual, Jesús
2018-01-01
This book presents an overview of the most recent advances in nonlinear science. It provides a unified view of nonlinear properties in many different systems and highlights many new developments. While volume 1 concentrates on mathematical theory and computational techniques and challenges, which are essential for the study of nonlinear science, this second volume deals with nonlinear excitations in several fields. These excitations can be localized and transport energy and matter in the form of breathers, solitons, kinks or quodons with very different characteristics, which are discussed in the book. They can also transport electric charge, in which case they are known as polarobreathers or solectrons. Nonlinear excitations can influence function and structure in biology, as for example, protein folding. In crystals and other condensed matter, they can modify transport properties, reaction kinetics and interact with defects. There are also engineering applications in electric lattices, Josephson junction a...
Use of acoustic vortices in acoustic levitation
DEFF Research Database (Denmark)
Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller
2009-01-01
Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...
Wael Akl; A. Baz
2014-01-01
Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which a...
Boyd, Robert W
2013-01-01
Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q
Impact of loudspeaker nonlinear distortion on personal sound zones
DEFF Research Database (Denmark)
Ma, Xiaohui; J. Hegarty, Patrick; Abildgaard Pedersen, Jan
2018-01-01
Personal sound zone systems aim at creating multiple listening zones within a shared space with minimum interference between zones, but the performance is often poorer than simulations predict and effects of nonlinear distortion are sometimes audible. This paper assesses the impact of nonlinear...... distortion on sound zones through simulations and measurements performed under anechoic conditions. Two sound zones, one bright and one dark, are created with acoustic contrast control using two loudspeaker arrays driven at 250 Hz. Nonlinear distortion is modelled using second or third order nonlinearities....... Simulations show that nonlinear distortion degrades the acoustic contrast, which is confirmed by experimental measurements. The harmonic distortion is audible in the dark zone. Frequency resolved measurements reveal that harmonic distortion contributes to contrast loss, but nonlinear effects...
Springer Handbook of Acoustics
Rossing, Thomas D
2007-01-01
Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and others. The Springer Handbook of Acoustics is an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents spanning: animal acoustics including infrasound and ultrasound, environmental noise control, music and human speech and singing, physiological and psychological acoustics, architectural acoustics, physical and engineering acoustics, signal processing, medical acoustics, and ocean acoustics. This handbook reviews the most important areas of acoustics, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest rese...
DEFF Research Database (Denmark)
Peters, Brady; Tamke, Martin; Nielsen, Stig Anton
2011-01-01
Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....
National Research Council Canada - National Science Library
Drazin, P. G
1992-01-01
This book is an introduction to the theories of bifurcation and chaos. It treats the solution of nonlinear equations, especially difference and ordinary differential equations, as a parameter varies...
Gasinski, Leszek
2005-01-01
Hausdorff Measures and Capacity. Lebesgue-Bochner and Sobolev Spaces. Nonlinear Operators and Young Measures. Smooth and Nonsmooth Analysis and Variational Principles. Critical Point Theory. Eigenvalue Problems and Maximum Principles. Fixed Point Theory.
Kuttruff, Heinrich
2006-01-01
This definitive textbook provides students with a comprehensive introduction to acoustics. Beginning with the basic physical ideas, Acoustics balances the fundamentals with engineering aspects, applications and electroacoustics, also covering music, speech and the properties of human hearing. The concepts of acoustics are exposed and applied in:room acousticssound insulation in buildingsnoise controlunderwater sound and ultrasoundScientifically thorough, but with mathematics kept to a minimum, Acoustics is the perfect introduction to acoustics for students at any level of mechanical, electrical or civil engineering courses and an accessible resource for architects, musicians or sound engineers requiring a technical understanding of acoustics and their applications.
Nonlinear Bubble Dynamics And The Effects On Propagation Through Near-Surface Bubble Layers
Leighton, Timothy G.
2004-11-01
Nonlinear bubble dynamics are often viewed as the unfortunate consequence of having to use high acoustic pressure amplitudes when the void fraction in the near-surface oceanic bubble layer is great enough to cause severe attenuation (e.g. >50 dB/m). This is seen as unfortunate since existing models for acoustic propagation in bubbly liquids are based on linear bubble dynamics. However, the development of nonlinear models does more than just allow quantification of the errors associated with the use of linear models. It also offers the possibility of propagation modeling and acoustic inversions which appropriately incorporate the bubble nonlinearity. Furthermore, it allows exploration and quantification of possible nonlinear effects which may be exploited. As a result, high acoustic pressure amplitudes may be desirable even in low void fractions, because they offer opportunities to gain information about the bubble cloud from the nonlinearities, and options to exploit the nonlinearities to enhance communication and sonar in bubbly waters. This paper presents a method for calculating the nonlinear acoustic cross-sections, scatter, attenuations and sound speeds from bubble clouds which may be inhomogeneous. The method allows prediction of the time dependency of these quantities, both because the cloud may vary and because the incident acoustic pulse may have finite and arbitrary time history. The method can be readily adapted for bubbles in other environments (e.g. clouds of interacting bubbles, sediments, structures, in vivo, reverberant conditions etc.). The possible exploitation of bubble acoustics by marine mammals, and for sonar enhancement, is explored.
Directory of Open Access Journals (Sweden)
Wael Akl
2014-12-01
Full Text Available Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which are invariably heavy and bulky. The transformation acoustics relationships that govern the operation of this class of interior acoustic cloaks are presented. Physical insights are given to relate these relationships to the reasons behind the effectiveness of the proposed interior acoustic cloaks. Finite element models are presented to demonstrate the characteristics of interior acoustic cloaks used in treating the interior walls of circular and square cavities both in the time and frequency domains. The obtained results emphasize the effectiveness of the proposed interior cloaks in eliminating the reflections of the acoustic waves from the walls of the treated cavities and thereby rendering these cavities acoustically quiet. It is important to note here that the proposed interior acoustic cloaks can find applications in acoustic cavities such as aircraft cabins and auditoriums as well as many other critical applications.
High efficiency and broadband acoustic diodes
Fu, Congyi; Wang, Bohan; Zhao, Tianfei; Chen, C. Q.
2018-01-01
Energy transmission efficiency and working bandwidth are the two major factors limiting the application of current acoustic diodes (ADs). This letter presents a design of high efficiency and broadband acoustic diodes composed of a nonlinear frequency converter and a linear wave filter. The converter consists of two masses connected by a bilinear spring with asymmetric tension and compression stiffness. The wave filter is a linear mass-spring lattice (sonic crystal). Both numerical simulation and experiment show that the energy transmission efficiency of the acoustic diode can be improved by as much as two orders of magnitude, reaching about 61%. Moreover, the primary working band width of the AD is about two times of the cut-off frequency of the sonic crystal filter. The cut-off frequency dependent working band of the AD implies that the developed AD can be scaled up or down from macro-scale to micro- and nano-scale.
Acoustic Neuroma Educational Video
Full Text Available ... Facts What is acoustic neuroma? Diagnosing Symptoms Side Effects Keywords Questions to ask Choosing a healthcare provider ... Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To Ask Treatment Options Back Overview Observation ...
Acoustic Neuroma Educational Video
Full Text Available ... Facts What is acoustic neuroma? Diagnosing Symptoms Side Effects Keywords World Language Videos Questions to ask Choosing ... Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To Ask Treatment Options Back Overview Observation ...
Atlantic Herring Acoustic Surveys
National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and underwater...
Tethys Acoustic Metadata Database
National Oceanic and Atmospheric Administration, Department of Commerce — The Tethys database houses the metadata associated with the acoustic data collection efforts by the Passive Acoustic Group. These metadata include dates, locations...
Laboratory Observations of Self-Excited Dust Acoustic Shocks
Heinrich, J.; Kim, S.-H.; Merlino, R. L.
2009-09-01
Repeated, self-excited dust acoustic shock waves (DASWs) have been observed in a dc glow discharge dusty plasma using high-speed video imaging. Two major observations are reported: (1) The self-steepening of a nonlinear dust acoustic wave (DAW) into a saw-tooth wave with sharp gradient in dust density, very similar to those found in numerical solutions of the fully nonlinear fluid equations for a nondispersive DAW [B. Eliasson and P. K. Shukla, Phys. Rev. E 69, 067401 (2004)], and (2) the collision and confluence of two DASWs.
Ruszczynski, Andrzej
2011-01-01
Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates the theory and the methods of nonlinear optimization in a unified, clear, and mathematically rigorous fashion, with detailed and easy-to-follow proofs illustrated by numerous examples and figures. The book covers convex analysis, the theory of optimality conditions, duality theory, and numerical methods for solving unconstrained and constrained optimization problems. It addresses not only classical material but also modern top...
Tutorial on architectural acoustics
Shaw, Neil; Talaske, Rick; Bistafa, Sylvio
2002-11-01
This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).
Vu, Cung Khac; Nihei, Kurt Toshimi; Johnson, Paul A.; Guyer, Robert A.; Ten Cate, James A.; Le Bas, Pierre-Yves; Larmat, Carene S.
2016-06-07
A system and method of characterizing properties of a medium from a non-linear interaction are include generating, by first and second acoustic sources disposed on a surface of the medium on a first line, first and second acoustic waves. The first and second acoustic sources are controllable such that trajectories of the first and second acoustic waves intersect in a mixing zone within the medium. The method further includes receiving, by a receiver positioned in a plane containing the first and second acoustic sources, a third acoustic wave generated by a non-linear mixing process from the first and second acoustic waves in the mixing zone; and creating a first two-dimensional image of non-linear properties or a first ratio of compressional velocity and shear velocity, or both, of the medium in a first plane generally perpendicular to the surface and containing the first line, based on the received third acoustic wave.
Vibro-acoustic modulation–based damage identification in a composite skin–stiffener structure
Ooijevaar, T.H.; Rogge, M.D.; Loendersloot, Richard; Warnet, Laurent; Akkerman, Remko; Tinga, Tiedo
2016-01-01
Vibro-acoustic modulation–based damage identification relies on the modulation of a high-frequency carrier signal by an intenser low-frequency vibration signal due to damage-induced structural nonlinearities. A time domain analysis of the vibro-acoustic modulation phenomena was presented at multiple
Electron acoustic vortices in the presence of inhomogeneous current
Energy Technology Data Exchange (ETDEWEB)
Haque, Q; Masood, W; Saleem, H [Theoretical Plasma Physics Division, PINSTECH, P O Nilore, Islamabad (Pakistan)], E-mail: qamar@pinstech.org.pk
2008-03-15
Linear and nonlinear dynamics of an electron acoustic wave in an inhomogeneous magnetized plasma are studied in the presence of non-uniform background current. The modified Rayleigh instability condition is found due to shear in the magnetic field and the current. A nonlinear stationary solution is also obtained in the form of tripolar vortices. The relevance of the present study to auroral and magnetotail plasmas is pointed out.
Nonlinear ultrasonics for material state awareness
Jacobs, L. J.
2014-02-01
Predictive health monitoring of structural components will require the development of advanced sensing techniques capable of providing quantitative information on the damage state of structural materials. By focusing on nonlinear acoustic techniques, it is possible to measure absolute, strength based material parameters that can then be coupled with uncertainty models to enable accurate and quantitative life prediction. Starting at the material level, this review will present current research that involves a combination of sensing techniques and physics-based models to characterize damage in metallic materials. In metals, these nonlinear ultrasonic measurements can sense material state, before the formation of micro- and macro-cracks. Typically, cracks of a measurable size appear quite late in a component's total life, while the material's integrity in terms of toughness and strength gradually decreases due to the microplasticity (dislocations) and associated change in the material's microstructure. This review focuses on second harmonic generation techniques. Since these nonlinear acoustic techniques are acoustic wave based, component interrogation can be performed with bulk, surface and guided waves using the same underlying material physics; these nonlinear ultrasonic techniques provide results which are independent of the wave type used. Recent physics-based models consider the evolution of damage due to dislocations, slip bands, interstitials, and precipitates in the lattice structure, which can lead to localized damage.
Parametric Room Acoustic Workflows
DEFF Research Database (Denmark)
Parigi, Dario; Svidt, Kjeld; Molin, Erik
2017-01-01
The paper investigates and assesses different room acoustics software and the opportunities they offer to engage in parametric acoustics workflow and to influence architectural designs. The first step consists in the testing and benchmarking of different tools on the basis of accuracy, speed...... and interoperability with Grasshopper 3d. The focus will be placed to the benchmarking of three different acoustic analysis tools based on raytracing. To compare the accuracy and speed of the acoustic evaluation across different tools, a homogeneous set of acoustic parameters is chosen. The room acoustics parameters...... included in the set are reverberation time (EDT, RT30), clarity (C50), loudness (G), and definition (D50). Scenarios are discussed for determining at different design stages the most suitable acoustic tool. Those scenarios are characterized, by the use of less accurate but fast evaluation tools to be used...
Deryabin, M. S.; Kasyanov, D. A.; Kurin, V. V.; Garasyov, M. A.
2016-05-01
We show that a significant energy redistribution occurs in the spectrum of reflected nonlinear waves, when an intense acoustic beam is reflected from an acoustically soft boundary, which manifests itself at short wave distances from a reflecting boundary. This effect leads to the appearance of extrema in the distributions of the amplitude and intensity of the field of the reflected acoustic beam near the reflecting boundary. The results of physical experiments are confirmed by numerical modeling of the process of transformation of nonlinear waves reflected from an acoustically soft boundary. Numerical modeling was performed by means of the Khokhlov—Zabolotskaya—Kuznetsov (KZK) equation.
Acoustic Metamaterials in Aeronautics
Directory of Open Access Journals (Sweden)
Giorgio Palma
2018-06-01
Full Text Available Metamaterials, man-made composites that are scaled smaller than the wavelength, have demonstrated a huge potential for application in acoustics, allowing the production of sub-wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, and acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities for the control of acoustic patterns and sound at sub-wavelength scales. Despite the tremendous growth in research on acoustic metamaterials during the last decade, the potential of metamaterial-based technologies in aeronautics has still not been fully explored, and its utilization is still in its infancy. Thus, the principal concepts mentioned above could very well provide a means to develop devices that allow the mitigation of the impact of civil aviation noise on the community. This paper gives a review of the most relevant works on acoustic metamaterials, analyzing them for their potential applicability in aeronautics, and, in this process, identifying possible implementation areas and interesting metabehaviors. It also identifies some technical challenges and possible future directions for research with the goal of unveiling the potential of metamaterials technology in aeronautics.
On some nonlinear effects in ultrasonic fields
Tjotta
2000-03-01
Nonlinear effects associated with intense sound fields in fluids are considered theoretically. Special attention is directed to the study of higher effects that cannot be described within the standard propagation models of nonlinear acoustics (the KZK and Burgers equations). The analysis is based on the fundamental equations of motion for a thermoviscous fluid, for which thermal equations of state exist. Model equations are derived and used to analyze nonlinear sources for generation of flow and heat, and other changes in the ambient state of the fluid. Fluctuations in the coefficients of viscosity and thermal conductivity caused by the sound field, are accounted for. Also considered are nonlinear effects induced in the fluid by flexural vibrations. The intensity and absorption of finite amplitude sound waves are calculated, and related to the sources for generation of higher order effects.
Nonlinear periodic waves in dusty plasma with variable dust charge
International Nuclear Information System (INIS)
Yadav, Lakhan Lal; Bharuthram, R.
2002-01-01
Using the reductive perturbation method, we present a theory of nonlinear periodic waves, viz. the cnoidal waves, in a dusty plasma consisting of electrons, ions, and cold dust grains with charge fluctuations, which in the limiting case reduce to dust acoustic solitons. It is found that the frequency of the dust acoustic cnoidal wave increases with its amplitude. The dust charge fluctuations are found to affect the characteristics of the cnoidal waves
Non-linearity parameter of binary liquid mixtures at elevated pressures
Indian Academy of Sciences (India)
. Ultrasonic studies in liquid mixtures provide valuable information about structure and interaction in such systems. The present investigation comprises of theoretical evaluation of the acoustic non-linearity parameter / of four binary liquid ...
Czech Academy of Sciences Publication Activity Database
Dos Santos, S.; Dvořáková, Zuzana; Caliez, M.; Převorovský, Zdeněk
2015-01-01
Roč. 138, č. 3 (2015) ISSN 0001-4966 Institutional support: RVO:61388998 Keywords : acousto-mechanical characterization of skin aging * nonlinear elastic wave spectroscopy (NEWS) * PM-space statistical approach Subject RIV: BI - Acoustics
Cylindrical and spherical dust-acoustic wave modulations in dusty ...
Indian Academy of Sciences (India)
Abstract. The nonlinear wave modulation of planar and non-planar (cylindrical and spherical) dust-acoustic waves (DAW) propagating in dusty plasmas, in the presence of non-extensive distribu- tions for ions and electrons is investigated. By employing multiple scales technique, a cylindrically and spherically modified ...
Nucleus-acoustic shock waves in white dwarfs
Indian Academy of Sciences (India)
S Jannat
2018-03-09
Mar 9, 2018 ... [17] of gravitational waves emitted by two merging black holes has opened up a new era of theoretical and observational research in astrophysics [17–19] which leads us to expect that in the near future a similar or dif- ferent kind of waves (like nucleus-acoustic (NA) waves. [20,21]) and associated nonlinear ...
Nilsson, Anders
2015-01-01
This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and inter...
Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities
Indian Academy of Sciences (India)
In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all R R . Assuming the existence of an upper and of a lower ...
Handbook of Engineering Acoustics
Möser, Michael
2013-01-01
This book examines the physical background of engineering acoustics, focusing on empirically obtained engineering experience as well as on measurement techniques and engineering methods for prognostics. Its goal is not only to describe the state of art of engineering acoustics but also to give practical help to engineers in order to solve acoustic problems. It deals with the origin, the transmission and the methods of the abating different kinds of air-borne and structure-borne sounds caused by various mechanisms – from traffic to machinery and flow-induced sound. In addition the modern aspects of room and building acoustics, as well as psychoacoustics and active noise control, are covered.
Localized Acoustic Surface Modes
Farhat, Mohamed
2015-08-04
We introduce the concept of localized acoustic surface modes (ASMs). We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.
Acoustic Technology Laboratory
Federal Laboratory Consortium — This laboratory contains an electro-magnetic worldwide data collection and field measurement capability in the area of acoustic technology. Outfitted by NASA Langley...
Shallow Water Acoustic Laboratory
Federal Laboratory Consortium — FUNCTION: Supports experimental research where high-frequency acoustic scattering and surface vibration measurements of fluid-loaded and non-fluid-loaded structures...
Laboratory for Structural Acoustics
Federal Laboratory Consortium — FUNCTION: Supports experimental research where acoustic radiation, scattering, and surface vibration measurements of fluid-loaded and non-fluid-loaded structures are...
Acoustic Levitation With Less Equipment
Barmatz, M. B.; Jacobi, N.
1983-01-01
Certain chamber shapes require fewer than three acoustic drivers. Levitation at center of spherical chamber attained using only one acoustic driver. Exitation of lowest spherical mode produces asymmetric acoustic potential well.
... CALENDAR DONATE NEWS Home Learn Back Learn about acoustic neuroma AN Facts What is acoustic neuroma? Diagnosing ... Italian Japanese Korean Portuguese Romanian Spanish What is Acoustic Neuroma? Each heading slides to reveal information. Important ...
Spectrum of the seismic-electromagnetic and acoustic waves caused by seismic and volcano activity
Directory of Open Access Journals (Sweden)
S. Koshevaya
2005-01-01
Full Text Available Modeling of the spectrum of the seismo-electromagnetic and acoustic waves, caused by seismic and volcanic activity, has been done. This spectrum includes the Electromagnetic Emission (EME, due to fracturing piezoelectrics in rocks and the Acoustic Emission (AE, caused by the excitation and the nonlinear passage of acoustic waves through the Earth's crust, the atmosphere, and the ionosphere. The investigated mechanism of the EME uses the model of fracturing and the crack motion. For its analysis, we consider a piezoelectric crystal under mechanical stresses, which cause the uniform crack motion, and, consequently, in the vicinity of the moving crack also cause non-stationary polarization currents. A possible spectrum of EME has been estimated. The underground fractures produce Very Low (VLF and Extremely Low Frequency (ELF acoustic waves, while the acoustic waves at higher frequencies present high losses and, on the Earth's surface, they are quite small and are not registered. The VLF acoustic wave is subject to nonlinearity under passage through the lithosphere that leads to the generation of higher harmonics and also frequency down-conversion, namely, increasing the ELF acoustic component on the Earth's surface. In turn, a nonlinear propagation of ELF acoustic wave in the atmosphere and the ionosphere leads to emerging the ultra low frequency (ULF acousto-gravity waves in the ionosphere and possible local excitation of plasma waves.
Multi-frequency acoustic metasurface for extraordinary reflection and sound focusing
Directory of Open Access Journals (Sweden)
Yi-Fan Zhu
2016-12-01
Full Text Available We theoretically and numerically present the design of multi-frequency acoustic metasurfaces (MFAMs with simple structure that can work not only at fundamental frequency, but also at their harmonic frequencies, which breaks the single frequency limitation in conventional resonance-based acoustic metasurfaces. The phase matched condition for achromatic manipulation is discussed. We demonstrate achromatic extraordinary reflection and sound focusing at 1700Hz, 3400Hz, and 5100Hz, that is, they have the same reflection direction and the same focusing position. This significant feature may pave the way to new type of acoustic metasurface, and will also extend acoustic metasurface applications to strongly nonlinear source cases.
Self excitation of second harmonic ion-acoustic waves in a weakly magnetized plasma
International Nuclear Information System (INIS)
Tsukabayashi, I.; Yagishita, T.; Nakamura, Y.
1994-01-01
Electrostatic ion-acoustic waves in a weakly magnetized plasma are investigated experimentally. It is observed that finite amplitudes ion acoustic waves excite a new second harmonic wave train behind the initial ion waves excite a new second harmonic wave train behind the initial ion waves in a parallel magnetic field. The excitation of higher harmonic waves can be explained by non-linearity of finite amplitude ion-acoustic waves. The newly excited second harmonics waves satisfy a dispersion relation of the ion-acoustic waves. (author). 3 refs, 5 figs
Energy Technology Data Exchange (ETDEWEB)
Khanzhin, V.G.; Nikulin, S.A. [Moscow State Inst. of Steel and Alloys (Russian Federation)
2005-06-01
A study of stress-corrosion cracking (SCC) of copper in 0.1M NaNO{sub 2} aqueous solution is presented. The fracture kinetics was monitored by measuring the acoustic emission (AE) signals. Macro- and micro-fractography analysis, using scanning electron microscopy (SEM), was employed to investigate the fracture mechanisms. Estimates of stress intensity factor, KI, and J-integral were derived in order to assess the resistance of copper to stress corrosion cracking. Two kinds of SCC tests under continuous circulation of the corrosive solution were employed in the present study: 1. Constant extension rate (2x10{sup -6}/s) tests on pre-cracked, middle tension (MT) panel specimens. 2. Tests on pre-cracked, compact tension (CT) specimens at a fixed (by a fixing bolt) opening of the crack walls ({delta} = 0.3 mm, K{sub i} = 27 MPax{radical}m). The time base for these tests was about two months. After the completion of the SCC test, the CT specimen was additionally tested, under a constant-rate (0.02 mm/s) off-center extension. In the both kinds of tests, the SCC fracture kinetics is found to exhibit two typical stages: Stage 1: SCC initiation stage (after a certain incubation period, T{sub i}, measured to be T{sub i} {approx_equal} 3-4 hours for MT specimens under constant extension, the corresponding stress was {sigma} {approx_equal} 40-70 MPa, and T{sub i} {approx_equal} 200 hours for CT specimens under a fixed crack wall opening). Stage 2: Active fracture process (SCC macro-fracture) distinguished by strong AE pulses (which are registered after time T{sub 2} {approx_equal} 8 hours for MT specimens and T{sub 2} {approx_equal} 800 hours for CT specimens). Fractography analysis has shown that the zone of SCC fracture in MT specimens extends to approximately 1,500 {mu}m. A 400-700 {mu}m deep zone of brittle transgranular fracture, which included small areas showing characteristic SCC 'striations', was observed adjacent to the fatigue pre-crack area. At higher
Acoustic Neuroma Educational Video
Full Text Available ... 30041 770-205-8211 info@ANAUSA.org The world’s #1 acoustic neuroma resource Click to learn more... ... is acoustic neuroma? Diagnosing Symptoms Side Effects Keywords World Language Videos Questions to ask Choosing a healthcare ...
Acoustics Critical Readiness Review
Ballard, Kenny
2010-01-01
This presentation reviews the status of the acoustic equipment from the medical operations perspective. Included is information about the acoustic dosimeters, sound level meter, and headphones that are planned for use while on orbit. Finally there is information about on-orbit hearing assessments.
DEFF Research Database (Denmark)
2008-01-01
The Handbook of Signal Processing in Acoustics will compile the techniques and applications of signal processing as they are used in the many varied areas of Acoustics. The Handbook will emphasize the interdisciplinary nature of signal processing in acoustics. Each Section of the Handbook...... will present topics on signal processing which are important in a specific area of acoustics. These will be of interest to specialists in these areas because they will be presented from their technical perspective, rather than a generic engineering approach to signal processing. Non-specialists, or specialists...... from different areas, will find the self-contained chapters accessible and will be interested in the similarities and differences between the approaches and techniques used in different areas of acoustics....
Jensen, Finn B; Porter, Michael B; Schmidt, Henrik
2011-01-01
Since the mid-1970s, the computer has played an increasingly pivotal role in the field of ocean acoustics. Faster and less expensive than actual ocean experiments, and capable of accommodating the full complexity of the acoustic problem, numerical models are now standard research tools in ocean laboratories. The progress made in computational ocean acoustics over the last thirty years is summed up in this authoritative and innovatively illustrated new text. Written by some of the field's pioneers, all Fellows of the Acoustical Society of America, Computational Ocean Acoustics presents the latest numerical techniques for solving the wave equation in heterogeneous fluid–solid media. The authors discuss various computational schemes in detail, emphasizing the importance of theoretical foundations that lead directly to numerical implementations for real ocean environments. To further clarify the presentation, the fundamental propagation features of the techniques are illustrated in color. Computational Ocean A...
25 years of dust acoustic waves
Merlino, Robert L.; Merlino
2014-12-01
The dust acoustic wave (DAW) was first discussed by P. K. Shukla in May of 1989 at the First Capri Workshop on Dusty Plasmas. In the past 25 years, the subsequent publication of the linear and nonlinear properties of the DAW (Rao, N. N., Shukla, P. K. and Yu, M. Y. 1990 Planet. Space Sci. 38, 543) has generated and sustained a large body of theoretical and experimental research that has clarified the physics of collective effects in dusty plasmas. A unique feature of the DAW is that it can be observed (literally) using laser illumination and high-speed videography, revealing details of wave-particle interactions at an unprecedented single particle level. This paper attempts to review some of the contributions and extensions of dust acoustic wave physics, as well as identify recent findings that illustrate the potential importance of this dust wave in the agglomeration of dust particles.
Calibration of acoustic emission transducers
International Nuclear Information System (INIS)
Leschek, W.C.
1976-01-01
A method is described for calibrating an acoustic emission transducer to be used in a pre-set frequency range. The absolute reception sensitivity of a reference transducer is determined at frequencies selected within the frequency range. The reference transducer and the acoustic emission transducer are put into acoustic communication with the surface of a limited acoustic medium representing an equivalent acoustic load appreciably identical to that of the medium in which the use of the acoustic emission transducer is intended. A blank random acoustic noise is emitted in the acoustic medium in order to establish a diffuse and reverberating sound field, after which the output responses of the reference transducer and of the acoustic emission transducer are obtained with respect to the diffuse and reverberating field, for selected frequencies. The output response of the acoustic emission transducer is compared with that of the reference transducer for the selected frequencies, so as to determine the reception sensitivity of the acoustic emission transducer [fr
Steerable sound transport in a 3D acoustic network
Xia, Bai-Zhan; Jiao, Jun-Rui; Dai, Hong-Qing; Yin, Sheng-Wen; Zheng, Sheng-Jie; Liu, Ting-Ting; Chen, Ning; Yu, De-Jie
2017-10-01
Quasi-lossless and asymmetric sound transports, which are exceedingly desirable in various modern physical systems, are almost always based on nonlinear or angular momentum biasing effects with extremely high power levels and complex modulation schemes. A practical route for the steerable sound transport along any arbitrary acoustic pathway, especially in a three-dimensional (3D) acoustic network, can revolutionize the sound power propagation and the sound communication. Here, we design an acoustic device containing a regular-tetrahedral cavity with four cylindrical waveguides. A smaller regular-tetrahedral solid in this cavity is eccentrically emplaced to break spatial symmetry of the acoustic device. The numerical and experimental results show that the sound power flow can unimpededly transport between two waveguides away from the eccentric solid within a wide frequency range. Based on the quasi-lossless and asymmetric transport characteristic of the single acoustic device, we construct a 3D acoustic network, in which the sound power flow can flexibly propagate along arbitrary sound pathways defined by our acoustic devices with eccentrically emplaced regular-tetrahedral solids.
Fu, Y. B.; Ogden, R. W.
2001-05-01
This collection of papers by leading researchers in the field of finite, nonlinear elasticity concerns itself with the behavior of objects that deform when external forces or temperature gradients are applied. This process is extremely important in many industrial settings, such as aerospace and rubber industries. This book covers the various aspects of the subject comprehensively with careful explanations of the basic theories and individual chapters each covering a different research direction. The authors discuss the use of symbolic manipulation software as well as computer algorithm issues. The emphasis is placed firmly on covering modern, recent developments, rather than the very theoretical approach often found. The book will be an excellent reference for both beginners and specialists in engineering, applied mathematics and physics.
Rajasekar, Shanmuganathan
2016-01-01
This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...
Nonlinear sound generation by high energy particles
International Nuclear Information System (INIS)
Westervelt, P.J.
1978-01-01
In connection with Project DUMAND, the proposal to utilize the ocean as a giant acoustic detector of neutrinos, the applicability of a recent theory of thermoacoustic arrays [Peter J. Westervelt and Richard S. Larson, J. Acoust. Soc. Am. 54, 121 (1973)] is studied. In the static case or at very low frequencies, about 10% of the coefficient of thermal expansion for water at 20 0 C can be attributed to Debye-like modes. Debye-like modes generate sound via the nonlinear mechanism responsible for the operation of the parametric acoustic array [Peter J. Westervelt, J. Acoust. Soc. Am. 35, 535 (1963)]. The contribution of the Debye-like modes to the thermal expansion coefficient and thus to the sound pressure is essentially independent of the ambient water temperature. Hence if the Debye-like modes are not fully excited as is postulated to be the case at high frequencies, then the thermal expansion coefficient will be less than the static value by an amount that causes it to vanish at about 6 0 C instead of at 4 0 C, the temperature of maximum water density. This theory is in agreement with recent measurements of the temperature dependence of sound generated by proton deposition in water [L. Sulak, et al., Proceedings of the La Jolla Workshop on Acoustic Detection of Neutrinos, 25--29 July 1977, Scripps Institute of Oceanography, U.C.L.A., San Diego, Hugh Bradner, Ed.
Detection and Classification of Whale Acoustic Signals
Xian, Yin
This dissertation focuses on two vital challenges in relation to whale acoustic signals: detection and classification. In detection, we evaluated the influence of the uncertain ocean environment on the spectrogram-based detector, and derived the likelihood ratio of the proposed Short Time Fourier Transform detector. Experimental results showed that the proposed detector outperforms detectors based on the spectrogram. The proposed detector is more sensitive to environmental changes because it includes phase information. In classification, our focus is on finding a robust and sparse representation of whale vocalizations. Because whale vocalizations can be modeled as polynomial phase signals, we can represent the whale calls by their polynomial phase coefficients. In this dissertation, we used the Weyl transform to capture chirp rate information, and used a two dimensional feature set to represent whale vocalizations globally. Experimental results showed that our Weyl feature set outperforms chirplet coefficients and MFCC (Mel Frequency Cepstral Coefficients) when applied to our collected data. Since whale vocalizations can be represented by polynomial phase coefficients, it is plausible that the signals lie on a manifold parameterized by these coefficients. We also studied the intrinsic structure of high dimensional whale data by exploiting its geometry. Experimental results showed that nonlinear mappings such as Laplacian Eigenmap and ISOMAP outperform linear mappings such as PCA and MDS, suggesting that the whale acoustic data is nonlinear. We also explored deep learning algorithms on whale acoustic data. We built each layer as convolutions with either a PCA filter bank (PCANet) or a DCT filter bank (DCTNet). With the DCT filter bank, each layer has different a time-frequency scale representation, and from this, one can extract different physical information. Experimental results showed that our PCANet and DCTNet achieve high classification rate on the whale
Parametric Room Acoustic workflows with real-time acoustic simulation
DEFF Research Database (Denmark)
Parigi, Dario
2017-01-01
The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages......The paper investigates and assesses the opportunities that real-time acoustic simulation offer to engage in parametric acoustics workflow and to influence architectural designs from early design stages...
Propagation of three-dimensional electron-acoustic solitary waves
International Nuclear Information System (INIS)
Shalaby, M.; El-Sherif, L. S.; El-Labany, S. K.; Sabry, R.
2011-01-01
Theoretical investigation is carried out for understanding the properties of three-dimensional electron-acoustic waves propagating in magnetized plasma whose constituents are cold magnetized electron fluid, hot electrons obeying nonthermal distribution, and stationary ions. For this purpose, the hydrodynamic equations for the cold magnetized electron fluid, nonthermal electron density distribution, and the Poisson equation are used to derive the corresponding nonlinear evolution equation, Zkharov-Kuznetsov (ZK) equation, in the small- but finite- amplitude regime. The ZK equation is solved analytically and it is found that it supports both solitary and blow-up solutions. It is found that rarefactive electron-acoustic solitary waves strongly depend on the density and temperature ratios of the hot-to-cold electron species as well as the nonthermal electron parameter. Furthermore, there is a critical value for the nonthermal electron parameter, which decides whether the electron-acoustic solitary wave's amplitude is decreased or increased by changing various plasma parameters. Importantly, the change of the propagation angles leads to miss the balance between the nonlinearity and dispersion; hence, the localized pulses convert to explosive/blow-up pulses. The relevance of this study to the nonlinear electron-acoustic structures in the dayside auroral zone in the light of Viking satellite observations is discussed.
Transmission acoustic microscopy investigation
Maev, Roman; Kolosov, Oleg; Levin, Vadim; Lobkis, Oleg
The nature of acoustic contrast, i.e. the connection of the amplitude and phase of the output signal of the acoustic microscope with the local values of the acoustic parameters of the sample (density, elasticity, viscosity) is a central problem of acoustic microscopy. A considerable number of studies have been devoted to the formation of the output signal of the reflection scanning acoustic microscope. For the transmission acoustic microscope (TAM) this problem has remained almost unstudied. Experimental investigation of the confocal system of the TAM was carried out on an independently manufactured laboratory mockup of the TAM with the working frequency of the 420 MHz. Acoustic lenses with the radius of curvature of about 500 microns and aperture angle of 45 deg were polished out in the end faces of two cylindrical sound conductors made from Al2O3 single crystals with an axis parallel to the axis C of the crystal (the length of the sound conductor is 20 mm; diameter, 6 mm). At the end faces of the sound conductor, opposite to the lenses, CdS transducers with a diameter of 2 mm were disposed. The electric channel of the TAM provided a possibility for registering the amplitude of the microscope output signal in the case of the dynamic range of the 50 dB.
The accidental (acoustical) tourist
Van Kirk, Wayne
2002-11-01
The acoustical phenomenon observed at an ancient temple in the Great Ball Court at Chichen Itza was described as ''little short of amazing--an ancient whispering gallery'' by Silvanus G. Morley, leader of the Carnegie Institute's archaeological team that excavated and restored these structures in the 1920s. Since then, many others have experienced the extraordinary acoustics at Chichen Itza and other Maya sites. Despite these reports, archaeologists and acousticians have until recently shown little interest in understanding these phenomena. After experiencing Chichen Itza's remarkable acoustics as a tourist in 1994, the author commenced collecting and disseminating information about acoustical phenomena there and at other Mayan sites, hoping to stimulate interest among archaeologists and acousticians. Were these designs accidental or intentional? If intentional, how was the knowledge obtained? How were acoustical features used? This paper highlights the author's collection of anecdotal reports of mysterious Mayan acoustics (http://http://www.ianlawton.com/pa1.htm), recommended reading for scientists and engineers who wish to pursue this fascinating study. Also recounted are some of the reactions of archaeologists-ranging from curious, helpful, and insightful to humorous and appalling--to outsiders' efforts to bring serious scientific attention to the new field of acoustical archaeology.
Translational illusion of acoustic sources by transformation acoustics.
Sun, Fei; Li, Shichao; He, Sailing
2017-09-01
An acoustic illusion of creating a translated acoustic source is designed by utilizing transformation acoustics. An acoustic source shifter (ASS) composed of layered acoustic metamaterials is designed to achieve such an illusion. A practical example where the ASS is made with naturally available materials is also given. Numerical simulations verify the performance of the proposed device. The designed ASS may have some applications in, e.g., anti-sonar detection.
Acoustic building infiltration measurement system
Muehleisen, Ralph T.; Raman, Ganesh
2018-04-10
Systems and methods of detecting and identifying a leak from a container or building. Acoustic pressure and velocity are measured. Acoustic properties are acquired from the measured values. The acoustic properties are converted to infiltration/leakage information. Nearfield Acoustic Holography (NAH) may be one method to detect the leakages from a container by locating the noise sources.
Electronegative nonlinear oscillating modes in plasmas
Panguetna, Chérif Souleman; Tabi, Conrad Bertrand; Kofané, Timoléon Crépin
2018-02-01
The emergence of nonlinear modulated waves is addressed in an unmagnetized electronegative plasma made of Boltzmann electrons, Boltzmann negative ions and cold mobile positive ions. The reductive perturbation method is used to reduce the dynamics of the whole system to a cubic nonlinear Schrödinger equation, whose the nonlinear and dispersion coefficients, P and Q, are function of the negative ion parameters, namely the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn). It is observed that these parameters importantly affect the formation of modulated ion-acoustic waves, either as exact solutions or via the activation of modulational instability. Especially, the theory of modulational instability is used to show the correlation between the parametric analysis and the formation of modulated solitons, obtained here as bright envelopes and kink-wave solitons.
Acoustical heat pumping engine
Wheatley, J.C.; Swift, G.W.; Migliori, A.
1983-08-16
The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium. 2 figs.
2016-06-28
the Deep Water project and participate in the NPAL Workshops, including Art Baggeroer (MIT), J. Beron- Vera (UMiami), M. Brown (UMiami), T...Kathleen E . Wage. The North Pacific Acoustic Laboratory deep-water acoustic propagation experiments in the Philippine Sea. J. Acoust. Soc. Am., 134(4...estimate of the angle α during PhilSea09, made from ADCP measurements at the site of the DVLA. Sim. A B1 B2 B3 C D E F Prof. # 0 4 4 4 5 10 16 20 α
NONLINEAR ULTRASONIC WAVE MODULATION TOMOGRAPHY FOR DAMAGED ZONE LOCATION
Czech Academy of Sciences Publication Activity Database
Převorovský, Zdeněk
-, - (2008), s. 14-17 ISSN 1213-3825. [WCNDT /17./. Šanghaj, 24.10.2008-28.10.2008] Institutional research plan: CEZ:AV0Z20760514 Keywords : nonlinear ultrasonic spectroscopy * defects localization * aircraft structure Subject RIV: BI - Acoustics
Smoothing identification of systems with small non-linearities
Czech Academy of Sciences Publication Activity Database
Kozánek, Jan; Piranda, J.
2003-01-01
Roč. 38, č. 1 (2003), s. 71-84 ISSN 0025-6455 R&D Projects: GA ČR GA101/00/1471 Institutional research plan: CEZ:AV0Z2076919 Keywords : identification * small non-linearities * smoothing methods Subject RIV: BI - Acoustics Impact factor: 0.237, year: 2003
Nonlinear waves in electron–positron–ion plasmas including charge ...
Indian Academy of Sciences (India)
2017-01-04
Jan 4, 2017 ... The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E0 was reduced. The results are compared with satellite observations. Keywords. Nonlinear waves; low frequency; ion-acoustic waves. PACS Nos 52.35.Qz; 52.35.Fp; 52.35 ...
Nonlinear wave propagation studies, dispersion modeling, and signal parameters correction
Czech Academy of Sciences Publication Activity Database
Převorovský, Zdeněk
..: ..., 2004, 00. [European Workshop on FP6-AERONEWS /1./. Naples (IT), 13.09.2004-16.09.2004] EU Projects: European Commission(XE) 502927 - AERO-NEWS Institutional research plan: CEZ:AV0Z2076919 Keywords : nodestructive testing * nonlinear elastic wave spectroscopy Subject RIV: BI - Acoustics
Nonlinear signal processing for ultrasonic imaging of material complexity
Czech Academy of Sciences Publication Activity Database
Dos Santos, S.; Vejvodová, Šárka; Převorovský, Zdeněk
2010-01-01
Roč. 59, č. 2 (2010), s. 108-117 ISSN 1736-6046 Institutional research plan: CEZ:AV0Z20760514 Keywords : nonlinear signal processing * TR-NEWS * symmetry analysis * DORT Subject RIV: BI - Acoustics Impact factor: 0.464, year: 2010 www.eap.ee/proceedings
Radiation acoustics and its applications
International Nuclear Information System (INIS)
Lyamshev, L.M.
1992-01-01
Radiation acoustics is a new branch of acoustics, developing on the boundary of acoustics, nuclear physics, elementary particles and high-energy physics. Its fundamentals are laying in the research of acoustical effects due to the interaction of penetrating radiation with matter. The study of radiation-acoustical effects leads to the new opportunities in the penetration radiation research (acoustical detection, radiation-acoustical dosimetry), study of the physical parameters of matter, in a solution of some applied problems of nondestructive testing, and also for the radiation-acoustical influence on physical and chemical structure of the matter. Results of theoretical and experimental investigations are given. Different mechanisms of the sound generation by penetrating radiation of liquids and solids are considered. Some applications - the radiation acoustical microscopy and visualisation, the acoustical detection of high energy X-ray particles and possibility of using of high energy neutrino beams in geoacoustics - are discussed
Non-reciprocity in nonlinear elastodynamics
Blanchard, Antoine; Sapsis, Themistoklis P.; Vakakis, Alexander F.
2018-01-01
Reciprocity is a fundamental property of linear time-invariant (LTI) acoustic waveguides governed by self-adjoint operators with symmetric Green's functions. The break of reciprocity in LTI elastodynamics is only possible through the break of time reversal symmetry on the micro-level, and this can be achieved by imposing external biases, adding nonlinearities or allowing for time-varying system properties. We present a Volterra-series based asymptotic analysis for studying spatial non-reciprocity in a class of one-dimensional (1D), time-invariant elastic systems with weak stiffness nonlinearities. We show that nonlinearity is neither necessary nor sufficient for breaking reciprocity in this class of systems; rather, it depends on the boundary conditions, the symmetries of the governing linear and nonlinear operators, and the choice of the spatial points where the non-reciprocity criterion is tested. Extension of the analysis to higher dimensions and time-varying systems is straightforward from a mathematical point of view (but not in terms of new non-reciprocal physical phenomena), whereas the connection of non-reciprocity and time irreversibility can be studied as well. Finally, we show that suitably defined non-reciprocity measures enable optimization, and can provide physical understanding of the nonlinear effects in the dynamics, enabling one to establish regimes of "maximum nonlinearity." We highlight the theoretical developments by means of a numerical example.
[Nonlinear magnetohydrodynamics
International Nuclear Information System (INIS)
1994-01-01
Resistive MHD equilibrium, even for small resistivity, differs greatly from ideal equilibrium, as do the dynamical consequences of its instabilities. The requirement, imposed by Faraday's law, that time independent magnetic fields imply curl-free electric fields, greatly restricts the electric fields allowed inside a finite-resistivity plasma. If there is no flow and the implications of the Ohm's law are taken into account (and they need not be, for ideal equilibria), the electric field must equal the resistivity times the current density. The vanishing of the divergence of the current density then provides a partial differential equation which, together with boundary conditions, uniquely determines the scalar potential, the electric field, and the current density, for any given resistivity profile. The situation parallels closely that of driven shear flows in hydrodynamics, in that while dissipative steady states are somewhat more complex than ideal ones, there are vastly fewer of them to consider. Seen in this light, the vast majority of ideal MHD equilibria are just irrelevant, incapable of being set up in the first place. The steady state whose stability thresholds and nonlinear behavior needs to be investigated ceases to be an arbitrary ad hoc exercise dependent upon the whim of the investigator, but is determined by boundary conditions and choice of resistivity profile
Nonlinear excitations in two-dimensional molecular structures with impurities
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Rasmussen, Kim; Christiansen, Peter Leth
1995-01-01
We study the nonlinear dynamics of electronic excitations interacting with acoustic phonons in two-dimensional molecular structures with impurities. We show that the problem is reduced to the nonlinear Schrodinger equation with a varying coefficient. The latter represents the influence...... of the impurity. Transforming the equation to the noninertial frame of reference coupled with the center of mass we investigate the soliton behavior in the close vicinity of the impurity. With the help of the lens transformation we show that the soliton width is governed by an Ermakov-Pinney equation. We also...... excitations. Analytical results are in good agreement with numerical simulations of the nonlinear Schrodinger equation....
Generation of broadband electrostatic noise by electron acoustic solitons
International Nuclear Information System (INIS)
Dubouloz, N.; Pottelette, R.; Malingre, M.; Treumann, R.A.
1991-01-01
Broadband electrostatic noise (BEN) bursts whose amplitude sometimes reaches about 100 mV m -1 have been observed by the Viking satellite in the dayside auroral zone. These emissions have been shown to be greatly influenced by nonlinear effects and to occur simultaneously with the observation of particle distributions favouring the destabilization of the electron acoustic mode. It is shown that electron acoustic solitons passing by the satellite would generate spectra that can explain the high-frequency part of BEN, above the electron plasma frequency
A fluid dynamic approach to the dust-acoustic soliton
International Nuclear Information System (INIS)
McKenzie, J.F.; Doyle, T.B.
2002-01-01
The properties of dust-acoustic solitons are derived from a fluid dynamic viewpoint in which conservation of total momentum, combined with the Bernoulli-like energy equations for each species, yields the structure equation for the heavy (or dust) speed in the stationary wave. This fully nonlinear approach reveals the crucial role played by the heavy sonic point in limiting the collective dust-acoustic Mach number, above which solitons cannot exist. An exact solution illustrates that the cold heavy species is compressed and this implies concomitant contraints on the potential and on the flow speed of the electrons and protons in the wave
A Fluid Dynamic Approach to the Dust-Acoustic Soliton
McKenzie, J. F.; Doyle, T. B.
2002-12-01
The properties of dust-acoustic solitons are derived from a fluid dynamic viewpoint in which conservation of total momentum, combined with the Bernoulli-like energy equations for each species, yields the structure equation for the heavy (or dust) speed in the stationary wave. This fully nonlinear approach reveals the crucial role played by the heavy sonic point in limiting the collective dust-acoustic Mach number, above which solitons cannot exist. An exact solution illustrates that the cold heavy species is compressed and this implies concomitant contraints on the potential and on the flow speed of the electrons and protons in the wave.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Jianfeng; Xuan, Fu-Zhen, E-mail: fzxuan@ecust.edu.cn [MOE Key Laboratory of Pressurized System and Safety, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China)
2014-05-28
The interrupted low cycle fatigue test of austenitic stainless steel was conducted and the dislocation structure and fatigue damage was evaluated subsequently by using both transmission electron microscope and nonlinear ultrasonic wave techniques. A “mountain shape” correlation between the nonlinear acoustic parameter and the fatigue life fraction was achieved. This was ascribed to the generation and evolution of planar dislocation structure and nonplanar dislocation structure such as veins, walls, and cells. The “mountain shape” correlation was interpreted successfully by the combined contribution of dislocation monopole and dipole with an internal-stress dependent term of acoustic nonlinearity.
Collisionless damping of dust-acoustic waves in a charge varying dusty plasma with nonextensive ions
Energy Technology Data Exchange (ETDEWEB)
Amour, Rabia; Tribeche, Mouloud [Faculty of Physics, Theoretical Physics Laboratory (TPL), Plasma Physics Group (PPG), University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria)
2014-12-15
The charge variation induced nonlinear dust-acoustic wave damping in a charge varying dusty plasma with nonextensive ions is considered. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust acoustic wave propagation to be described by a damped Korteweg-de Vries (dK-dV) equation the coefficients of which depend sensitively on the nonextensive parameter q. The damping term, solely due to the dust charge variation, is affected by the ion nonextensivity. For the sake of completeness, the possible effects of nonextensivity and collisionless damping on weakly nonlinear wave packets described by the dK-dV equation are succinctly outlined by deriving a nonlinear Schrödinger-like equation with a complex nonlinear coefficient.
Collisionless damping of dust-acoustic waves in a charge varying dusty plasma with nonextensive ions
International Nuclear Information System (INIS)
Amour, Rabia; Tribeche, Mouloud
2014-01-01
The charge variation induced nonlinear dust-acoustic wave damping in a charge varying dusty plasma with nonextensive ions is considered. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust acoustic wave propagation to be described by a damped Korteweg-de Vries (dK-dV) equation the coefficients of which depend sensitively on the nonextensive parameter q. The damping term, solely due to the dust charge variation, is affected by the ion nonextensivity. For the sake of completeness, the possible effects of nonextensivity and collisionless damping on weakly nonlinear wave packets described by the dK-dV equation are succinctly outlined by deriving a nonlinear Schrödinger-like equation with a complex nonlinear coefficient
Acoustic Neuroma Educational Video
Full Text Available ... a healthcare provider Request a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a healthcare ...
Barmatz, M. B.; Granett, D.; Lee, M. C.
1984-01-01
Uncontaminated environments for highly-pure material processing provided within completely sealed levitation chamber that suspends particles by acoustic excitation. Technique ideally suited for material processing in low gravity environment of space.
National Research Council Canada - National Science Library
Homes, Christopher
1997-01-01
...). When the indirect manifestations of the ZPF are interpreted as due to radiation pressure, acoustic noise can provide an excellent analog to investigate the Casimir effect as well as other effects due to the ZPF...
Acoustic Neuroma Educational Video
Full Text Available ... a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects ... To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a healthcare provider Request a patient kit ...
Acoustic Neuroma Educational Video
Full Text Available ... Choosing a healthcare provider Request a patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing Symptoms Side effects Question To Ask Treatment Options Back Overview Observation Radiation Surgery Choosing a ...
Acoustic ambient noise recorder
Digital Repository Service at National Institute of Oceanography (India)
Saran, A.K.; Navelkar, G.S.; Almeida, A.M.; More, S.R.; Chodankar, P.V.; Murty, C.S.
with a robust outfit that can withstand high pressures and chemically corrosion resistant materials. Keeping these considerations in view, a CMOS micro-controller-based marine acoustic ambient noise recorder has been developed with a real time clock...
Acoustic Neuroma Educational Video
Full Text Available ... Learn more about ANA About ANA Mission, Vision & Values Shop ANA Leadership & Staff Annual Reports Acoustic Neuroma ... 8211 info@ANAUSA.org About ANA Mission, Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn ...
Acoustic Neuroma Educational Video
Full Text Available ... ANA About ANA Mission, Vision & Values Shop ANA Leadership & Staff Annual Reports Acoustic Neuroma Association 600 Peachtree ... info@ANAUSA.org About ANA Mission, Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn Educational ...
Acoustic Neuroma Educational Video
Full Text Available ... patient kit Treatment Options Overview Observation Radiation Surgery What is acoustic neuroma Diagnosing ... Back Community Patient Stories Share Your Story Video Stories Caregivers Milestones Gallery Submit Your Milestone Team ANA Volunteer ...
Acoustic Neuroma Educational Video
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Autonomous Acoustic Receiver System
Federal Laboratory Consortium — FUNCTION: Collects underwater acoustic data and oceanographic data. Data are recorded onboard an ocean buoy and can be telemetered to a remote ship or shore station...
Acoustic MIMO signal processing
Huang, Yiteng; Chen, Jingdong
2006-01-01
A timely and important book addressing a variety of acoustic signal processing problems under multiple-input multiple-output (MIMO) scenarios. It uniquely investigates these problems within a unified framework offering a novel and penetrating analysis.
Acoustic Neuroma Educational Video
Full Text Available ... Back Learn more about ANA About ANA Mission, Vision & Values Shop ANA Leadership & Staff Annual Reports Acoustic ... 205-8211 info@ANAUSA.org About ANA Mission, Vision & Values Leadership & Staff Annual Reports Shop ANA Home ...
Thermal Acoustic Fatigue Apparatus
Federal Laboratory Consortium — The Thermal Acoustic Fatigue Apparatus (TAFA) is a progressive wave tube test facility that is used to test structures for dynamic response and sonic fatigue due to...
Acoustic Neuroma Educational Video
Full Text Available ... Spanish Washington Support Group Leslie of Stone Mountain, ... Providers Acoustic Neuroma Association Donate Now Newly Diagnosed What is AN? Request a Patient Kit Treatment Options Get Support Find a Provider Discussion Forum ...
Acoustic Neuroma Educational Video
Full Text Available ... Mission, Vision & Values Shop ANA Leadership & Staff Annual Reports Acoustic Neuroma Association 600 Peachtree Parkway Suite 108 ... About ANA Mission, Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn Educational Video English English ...
National Aeronautics and Space Administration — An acoustic igniter eliminates the need to use electrical energy to drive spark systems to initiate combustion in liquid-propellant rockets. It does not involve the...
Department of Cybernetic Acoustics
The development of the theory, instrumentation and applications of methods and systems for the measurement, analysis, processing and synthesis of acoustic signals within the audio frequency range, particularly of the speech signal and the vibro-acoustic signal emitted by technical and industrial equipments treated as noise and vibration sources was discussed. The research work, both theoretical and experimental, aims at applications in various branches of science, and medicine, such as: acoustical diagnostics and phoniatric rehabilitation of pathological and postoperative states of the speech organ; bilateral ""man-machine'' speech communication based on the analysis, recognition and synthesis of the speech signal; vibro-acoustical diagnostics and continuous monitoring of the state of machines, technical equipments and technological processes.
Acoustic Neuroma Educational Video
Full Text Available ... 1 acoustic neuroma resource Click to learn more... LOGIN CALENDAR DONATE NEWS Home Learn Back Learn about ... Webinar Library Newsletter Library Patient Info Booklets Member Login Research ANA Survey/Registry AN Research Patient Registry ...
Acoustic Neuroma Educational Video
Full Text Available ... About ANA Mission, Vision & Values Shop ANA Leadership & Staff Annual Reports Acoustic Neuroma Association 600 Peachtree Parkway ... ANAUSA.org About ANA Mission, Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn Educational Video ...
Acoustic Neuroma Educational Video
Full Text Available ... Click to learn more... LOGIN CALENDAR DONATE NEWS Home Learn Back Learn about acoustic neuroma AN Facts ... Vision & Values Leadership & Staff Annual Reports Shop ANA Home Learn Educational Video English English Arabic Catalan Chinese ( ...
Smith, Richard W.
1979-01-01
An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.
Principles of musical acoustics
Hartmann, William M
2013-01-01
Principles of Musical Acoustics focuses on the basic principles in the science and technology of music. Musical examples and specific musical instruments demonstrate the principles. The book begins with a study of vibrations and waves, in that order. These topics constitute the basic physical properties of sound, one of two pillars supporting the science of musical acoustics. The second pillar is the human element, the physiological and psychological aspects of acoustical science. The perceptual topics include loudness, pitch, tone color, and localization of sound. With these two pillars in place, it is possible to go in a variety of directions. The book treats in turn, the topics of room acoustics, audio both analog and digital, broadcasting, and speech. It ends with chapters on the traditional musical instruments, organized by family. The mathematical level of this book assumes that the reader is familiar with elementary algebra. Trigonometric functions, logarithms and powers also appear in the book, but co...
National Aeronautics and Space Administration — Techsburg is teaming with the Vibration and Acoustics Laboratory of Virginia Tech to propose a non-linear analytical tool for designing Herschel-Quincke (HQ)...
DEFF Research Database (Denmark)
Mitchell, Peter J; Klarskov, Niels; Telford, Karen J
2011-01-01
Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis.......Anal acoustic reflectometry is a new technique of assessing anal sphincter function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, the opening and closing elastance, and hysteresis....
Nonlinear Diffusion and Transient Osmosis
International Nuclear Information System (INIS)
Igarashi, Akira; Rondoni, Lamberto; Botrugno, Antonio; Pizzi, Marco
2011-01-01
We investigate both analytically and numerically the concentration dynamics of a solution in two containers connected by a narrow and short channel, in which diffusion obeys a porous medium equation. We also consider the variation of the pressure in the containers due to the flow of matter in the channel. In particular, we identify a phenomenon, which depends on the transport of matter across nano-porous membranes, which we call ''transient osmosis . We find that nonlinear diffusion of the porous medium equation type allows numerous different osmotic-like phenomena, which are not present in the case of ordinary Fickian diffusion. Experimental results suggest one possible candidate for transiently osmotic processes. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors
Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)
1995-01-01
An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.
Westra, H.J.R.
2012-01-01
In this Thesis, nonlinear dynamics and nonlinear interactions are studied from a micromechanical point of view. Single and doubly clamped beams are used as model systems where nonlinearity plays an important role. The nonlinearity also gives rise to rich dynamic behavior with phenomena like
Mechanical Seal Opening Condition Monitoring Based on Acoustic Emission Technology
Directory of Open Access Journals (Sweden)
Erqing Zhang
2014-06-01
Full Text Available Since the measurement of mechanical sealing film thickness and just-lift-off time is very difficult, the sealing film condition monitoring method based on acoustic emission signal is proposed. The mechanical seal acoustic emission signal present obvious characteristics of time-varying nonlinear and pulsating. In this paper, the acoustic emission signal is used to monitor the seal end faces just-lift-off time and friction condition. The acoustic emission signal is decomposed by empirical mode decomposition into a series of intrinsic mode function with independent characteristics of different time scales and different frequency band. The acoustic emission signal only generated by end faces friction is obtained by eliminating the false intrinsic mode function components. The correlation coefficient of acoustic emission signal and Multi-scale Laplace Wavelet is calculated. It is proved that the maximum frequency (8000 Hz of the correlation coefficient is appeared at the spindle speed of 300 rpm. And at this time (300 rpm the end faces have just lifted off. By a set of mechanical oil seal running test, it is demonstrated that this method could accurately identify mechanical seal end faces just-lift-off time and friction condition.
Acoustic tweezing of particles using decaying opposing travelling surface acoustic waves (DOTSAW).
Ng, Jia Wei; Devendran, Citsabehsan; Neild, Adrian
2017-10-11
Surface acoustic waves offer a versatile and biocompatible method of manipulating the location of suspended particles or cells within microfluidic systems. The most common approach uses the interference of identical frequency, counter propagating travelling waves to generate a standing surface acoustic wave, in which particles migrate a distance less than half the acoustic wavelength to their nearest pressure node. The result is the formation of a periodic pattern of particles. Subsequent displacement of this pattern, the prerequisite for tweezing, can be achieved by translation of the standing wave, and with it the pressure nodes; this requires changing either the frequency of the pair of waves, or their relative phase. Here, in contrast, we examine the use of two counterpropagating traveling waves of different frequency. The non-linearity of the acoustic forces used to manipulate particles, means that a small frequency difference between the two waves creates a substantially different force field, which offers significant advantages. Firstly, this approach creates a much longer range force field, in which migration takes place across multiple wavelengths, and causes particles to be gathered together in a single trapping site. Secondly, the location of this single trapping site can be controlled by the relative amplitude of the two waves, requiring simply an attenuation of one of the electrical drive signals. Using this approach, we show that by controlling the powers of the opposing incoherent waves, 5 μm particles can be migrated laterally across a fluid flow to defined locations with an accuracy of ±10 μm.
Dynamic nonlinear elasticity in geo materials
International Nuclear Information System (INIS)
Ostrovsky, L.A.; Johnson, P.A.
2001-01-01
The nonlinear elastic behaviour of earth materials is an extremely rich topic, one that has broad implications to earth and materials sciences, including strong ground motion, rock physics, nondestructive evaluation and materials science. The mechanical properties of rock appear to place it in a broader class of materials, it can be named the Structural nonlinear elasticity class (also Mesoscopic/nano scale elasticity, or MS/NSE class). These terms are in contrast to materials that display classical, Atomic Elasticity, such as most fluids and monocrystalline solids. The difference between these two categories of materials is both in intensity and origin of their nonlinear response. The nonlinearity of atomic elastic materials is due to the atomic/molecular lattice anharmonicity. The latter is relatively small because the intermolecular forces are extremely strong. In contrast, the materials considered below contain small soft features that it is called the bond system (cracks, grain contacts, dislocations, etc.) within a hard matrix and relaxation (slow dynamical effects) are characteristic, non of which appear in atomic elastic materials. The research begins with a brief historical background from nonlinear acoustics to the recent developments in rock nonlinearity. This is followed by an overview of some representative laboratory measurements which serve as primary indicators of nonlinear behaviour, followed by theoretical development, and finally, mention a variety of observations of nonlinearity under field conditions and applications to nondestructive testing of materials. The goal is not to survey all papers published in the are but to demonstrate some experimental and theoretical results and ideas that will the reader to become oriented in this broad and rapidly growing area bridging macro-, meso- and microscale (nano scale) phenomena in physics, materials science, and geophysics
Acoustic comfort in eating establishments
DEFF Research Database (Denmark)
Svensson, David; Jeong, Cheol-Ho; Brunskog, Jonas
2014-01-01
The subjective concept of acoustic comfort in eating establishments has been investigated in this study. The goal was to develop a predictive model for the acoustic comfort, by means of simple objective parameters, while also examining which other subjective acoustic parameters could help explain...... the feeling of acoustic comfort. Through several layers of anal ysis, acoustic comfort was found to be rather complex, and could not be explained entirely by common subjective parameters such as annoyance, intelligibility or privacy. A predictive model for the mean acoustic comfort for an eating establishment...
Electron-acoustic Instability Simulated By Modified Zakharov Equations
Jásenský, V.; Fiala, V.; Vána, O.; Trávnícek, P.; Hellinger, P.
We present non-linear equations describing processes in plasma when electron - acoustic waves are excited. These waves are present for instance in the vicinity of Earth's bow shock and in the polar ionosphere. Frequently they are excited by an elec- tron beam in a plasma with two electron populations, a cold and hot one. We derive modified Zakharov equations from kinetic theory for such a case together with numer- ical method for solving of this type of equations. Bispectral analysis is used to show which non-linear wave processes are of importance in course of the instability. Finally, we compare these results with similar simulations using Vlasov approach.
Nonlinear Coherent Structures, Microbursts and Turbulence
Lakhina, G. S.
2015-12-01
Nonlinear waves are found everywhere, in fluids, atmosphere, laboratory, space and astrophysical plasmas. The interplay of nonlinear effects, dispersion and dissipation in the medium can lead to a variety of nonlinear waves and turbulence. Two cases of coherent nonlinear waves: chorus and electrostatic solitary waves (ESWs) and their impact on modifying the plasma medium are discussed. Chorus is a right-hand, circularly-polarized electromagnetic plane wave. Dayside chorus is a bursty emission composed of rising frequency "elements" with duration of ~0.1 to 1.0 s. Each element is composed of coherent subelements with durations of ~1 to 100 ms or more. The cyclotron resonant interaction between energetic electrons and the coherent chorus waves is studied. An expression for the pitch angle transport due to this interaction is derived considering a Gaussian distribution for the time duration of the chorus elements. The rapid pitch scattering can provide an explanation for the ionospheric microbursts of ~0.1 to 0.5 s in bremsstrahlung x-rays formed by ~10-100 keV precipitating electrons. On the other hand, the ESWs are observed in the electric field component parallel to the background magnetic field, and are usually bipolar or tripolar. Generation of coherent ESWs has been explained in terms of nonlinear fluid models of ion- and electron-acoustic solitons and double layers (DLs) based on Sagdeev pseudopotential technique. Fast Fourier transform of electron- and ion-acoustic solitons/DLs produces broadband wave spectra which can explain the properties of the electrostatic turbulence observed in the magnetosheath and plasma sheet boundary layer, and in the solar wind, respectively.
Nonlinear magnetoacoustic wave propagation with chemical reactions
Margulies, Timothy Scott
2002-11-01
The magnetoacoustic problem with an application to sound wave propagation through electrically conducting fluids such as the ocean in the Earth's magnetic field, liquid metals, or plasmas has been addressed taking into account several simultaneous chemical reactions. Using continuum balance equations for the total mass, linear momentum, energy; as well as Maxwell's electrodynamic equations, a nonlinear beam equation has been developed to generalize the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation for a fluid with linear viscosity but nonlinear and diffraction effects. Thermodynamic parameters are used and not tailored to only an adiabatic fluid case. The chemical kinetic equations build on a relaxing media approach presented, for example, by K. Naugolnukh and L. Ostrovsky [Nonlinear Wave Processes in Acoustics (Cambridge Univ. Press, Cambridge, 1998)] for a linearized single reaction and thermodynamic pressure equation of state. Approximations for large and small relaxation times and for magnetohydrodynamic parameters [Korsunskii, Sov. Phys. Acoust. 36 (1990)] are examined. Additionally, Cattaneo's equation for heat conduction and its generalization for a memory process rather than a Fourier's law are taken into account. It was introduced for the heat flux depends on the temperature gradient at an earlier time to generate heat pulses of finite speed.
Oblique Modulation of Ion-Acoustic Waves in a Warm Plasma
International Nuclear Information System (INIS)
Xue Jukui; Tang Rongan
2003-01-01
The stability of oblique modulation of ion-acoustic waves in an unmagnetized warm plasma is studied. A nonlinear Schroedinger equation governing the slow modulation of the wave amplitude is derived. The effect of temperature on the oblique modulational instability of the ion-acoustic wave is investigated. It is found that the ion temperature significantly changes the domain of the modulational instability in the k-θ plane
Effect of finite ion-temperature on ion-acoustic solitary waves in an inhomogeneous plasma
International Nuclear Information System (INIS)
Shivamoggi, B.K.
1981-01-01
The propagation of weakly nonlinear ion-acoustic waves in an inhomogeneous plasma is studied taking into account the effect of finite ion temperature. It is found that, whereas both the amplitude and the velocity of propagation decrease as the ion-acoustic solitary wave propagates into regions of higher density, the effect of a finite ion temperature is to reduce the amplitude but enhance the velocity of propagation of the solitary wave. (author)
Nonlinear acoustic wave propagating in one-dimensional layered system
International Nuclear Information System (INIS)
Yun, Y.; Miao, G.Q.; Zhang, P.; Huang, K.; Wei, R.J.
2005-01-01
The propagation of finite-amplitude plane sound in one-dimensional layered media is studied by the extended method of transfer matrix formalism. For the periodic layered system consisting of two alternate types of liquid, the energy distribution and the phase vectors of the interface vibration are computed and analyzed. It is found that in the pass-band, the second harmonic of sound wave can propagate with the characteristic modulation
Application of inertia-induced excitation theory for nonlinear acoustic ...
Indian Academy of Sciences (India)
estimated. By these calculations, a generalized statement is reported that all possible sound ..... we carry out order-by-order analysis of eqs (9)–(13) in a stretched coordinate system ..... The financial support by the CSIR received through.
Inhibition of nonlinear acoustic cavitation dynamics in liquid CO2
Iersel, van M.M.; Cornel, J.; Benes, N.E.; Keurentjes, J.T.F.
2007-01-01
The authors present a model to study ultrasound-induced cavitation dynamics in liquid carbon dioxide (CO2), which includes descriptions for momentum, mass, and energy transport. To assist in the interpretation of these results, numerical simulations are presented for an argon cavity in water. For
Nonlinear propagation of weakly relativistic ion-acoustic waves in ...
Indian Academy of Sciences (India)
2016-10-06
Oct 6, 2016 ... σ = 0.01 and q = 0.6, (b) for different values of q when σ = 0.01 and p = 0.4 and (c) for different values of σ when ... and electron thermal velocities, as follows: ∂ni. ∂t. +. ∂(niui). ∂x ..... [1] K A Holcomb and T Tajima, Phys. Rev ...
Acoustic Microscopy and Nonlinear Effects in Pressurized Superfluid Helium
1993-08-31
Fresnel or parabolic approxi nations [16,17]. With the development of the Khokhlov-Zabolotskaya-Kuznetsov ( KZK ) paratolic equation [18,191, which...sound waves in a thermoviscous liquid by means of the KZK equation. (2) Hart and Hamilton [261 employed a con- vergent coordinate system that...improves the efficiency of the numerical solution of the KZK equa- tion for focused beams. (3) Lucas and Muir [27] developed an equivalency relationship
Magnetoactive Acoustic Metamaterials.
Yu, Kunhao; Fang, Nicholas X; Huang, Guoliang; Wang, Qiming
2018-04-11
Acoustic metamaterials with negative constitutive parameters (modulus and/or mass density) have shown great potential in diverse applications ranging from sonic cloaking, abnormal refraction and superlensing, to noise canceling. In conventional acoustic metamaterials, the negative constitutive parameters are engineered via tailored structures with fixed geometries; therefore, the relationships between constitutive parameters and acoustic frequencies are typically fixed to form a 2D phase space once the structures are fabricated. Here, by means of a model system of magnetoactive lattice structures, stimuli-responsive acoustic metamaterials are demonstrated to be able to extend the 2D phase space to 3D through rapidly and repeatedly switching signs of constitutive parameters with remote magnetic fields. It is shown for the first time that effective modulus can be reversibly switched between positive and negative within controlled frequency regimes through lattice buckling modulated by theoretically predicted magnetic fields. The magnetically triggered negative-modulus and cavity-induced negative density are integrated to achieve flexible switching between single-negative and double-negative. This strategy opens promising avenues for remote, rapid, and reversible modulation of acoustic transportation, refraction, imaging, and focusing in subwavelength regimes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Robust Sensing of Approaching Vehicles Relying on Acoustic Cues
Directory of Open Access Journals (Sweden)
Mitsunori Mizumachi
2014-05-01
Full Text Available The latest developments in automobile design have allowed them to be equipped with various sensing devices. Multiple sensors such as cameras and radar systems can be simultaneously used for active safety systems in order to overcome blind spots of individual sensors. This paper proposes a novel sensing technique for catching up and tracking an approaching vehicle relying on an acoustic cue. First, it is necessary to extract a robust spatial feature from noisy acoustical observations. In this paper, the spatio-temporal gradient method is employed for the feature extraction. Then, the spatial feature is filtered out through sequential state estimation. A particle filter is employed to cope with a highly non-linear problem. Feasibility of the proposed method has been confirmed with real acoustical observations, which are obtained by microphones outside a cruising vehicle.
Nonplanar ion acoustic waves with kappa-distributed electrons
International Nuclear Information System (INIS)
Sahu, Biswajit
2011-01-01
Using the standard reductive perturbation technique, nonlinear cylindrical and spherical Kadomtsev-Petviashvili equations are derived for the propagation of ion acoustic solitary waves in an unmagnetized collisionless plasma with kappa distributed electrons and warm ions. The influence of kappa-distributed electrons and the effects caused by the transverse perturbation on cylindrical and spherical ion acoustic waves (IAWs) are investigated. It is observed that increase in the kappa distributed electrons (i.e., decreasing κ) decreases the amplitude of the solitary electrostatic potential structures. The numerical results are presented to understand the formation of ion acoustic solitary waves with kappa-distributed electrons in nonplanar geometry. The present investigation may have relevance in the study of propagation of IAWs in space and laboratory plasmas.
Nonlinear interactions in magnetised piezoelectric semiconductor plasmas
International Nuclear Information System (INIS)
Sharma, Giriraj; Ghosh, S.
2000-01-01
Based on hydrodynamics model of plasmas an analytical investigation of frequency modulational interaction between copropagating high frequency pump and acoustic mode and consequent amplification (steady-state and transient) of the modulated waves is carried out in a magnetised piezoelectric semiconductor medium. The phenomenon of modulation amplification is treated as four wave interaction process involving cubic nonlinearity of the medium. Gain constants, threshold-pump intensities and optimum-pulse duration for the onset of modulational instabilities are estimated. The analysis has been performed in non-dispersive regime of the acoustic mode, which is one of the preconditions for achieving an appreciable initial steady-state growth of the modulated signal wave. It is found that the transient gain diminishes very rapidly if one chooses the pump pulse duration beyond the maximum gain point. Moreover, the desired value of the gain can be obtained by adjusting intensity and pulse duration of the pump and doping concentration of the medium concerned. (author)
International Nuclear Information System (INIS)
Tournat, V.; Gusev, V.E.; Castagnede, B.
2004-01-01
First laboratory-scale experimental observation of both subharmonics excitation and significant increase in noise level caused by propagation of the acoustic wave in unconsolidated granular material is reported. The bifurcation phenomenon, taking place above a critical level of acoustic excitation (and opening the subharmonics route to chaos) is attributed to the interaction of acoustic wave with distributed system of highly nonlinear inter-grain contacts. The estimates demonstrated that these are weak contacts (loaded at least two orders of magnitude weaker than in average) that might be responsible for the observed nonlinear effects. The additional intermittent contacts created by the acoustic wave (which are open in the absence of acoustic loading) can also contribute. In the clapping (tapping) regime, each of these contacts individually is similar to an impact oscillator, for which the scenario of period doubling cascade and the transition to chaotic behavior has been predicted theoretically and observed experimentally earlier. The experiments confirm that the nonlinear interactions of acoustic waves in granular assemblages are highly sensitive to the fraction of weakly loaded (and unloaded) contacts, information on which is difficult to access by any other experimental methods
Propagation of acoustic waves in a stratified atmosphere, 1
Kalkofen, W.; Rossi, P.; Bodo, G.; Massaglia, S.
1994-01-01
This work is motivated by the chromospheric 3 minute oscillations observed in the K(sub 2v) bright points. We study acoustic gravity waves in a one-dimensional, gravitationally stratified, isothermal atmosphere. The oscillations are excited either by a velocity pulse imparted to a layer in an atmosphere of infinite vertical extent, or by a piston forming the lower boundary of a semi-infinite medium. We consider both linear and non-linear waves.
Advanced Active Acoustics Lab (AAAL)
Federal Laboratory Consortium — The Advanced Active Acoustics Lab (AAAL) is a state-of-the-art Undersea Warfare (USW) acoustic data analysis facility capable of both active and passive underwater...
Sea Turtle Acoustic Telemetry Data
National Oceanic and Atmospheric Administration, Department of Commerce — Acoustic transmitters attached to sea turtles captured in various fishing gear enable the animals to be passively tracked. Acoustic receivers set up in an array...
Perspective: Acoustic metamaterials in transition
Wu, Ying; Yang, Min; Sheng, Ping
2017-01-01
Acoustic metamaterials derive their novel characteristics from the interaction between acoustic waves with designed structures. Since its inception seventeen years ago, the field has been driven by fundamental geometric and physical principles
A Century of Acoustic Metrology
DEFF Research Database (Denmark)
Rasmussen, Knud
1998-01-01
The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect.......The development in acoustic measurement technique over the last century is reviewed with special emphasis on the metrological aspect....
Acoustic Levitation Containerless Processing
Whymark, R. R.; Rey, C. A.
1985-01-01
This research program consists of the development of acoustic containerless processing systems with applications in the areas of research in material sciences, as well as the production of new materials, solid forms with novel and unusual microstructures, fusion target spheres, and improved optical fibers. Efforts have been focused on the containerless processing at high temperatures for producing new kinds of glasses. Also, some development has occurred in the areas of containerlessly supporting liquids at room temperature, with applications in studies of fluid dynamics, potential undercooling of liquids, etc. The high temperature area holds the greatest promise for producing new kinds of glasses and ceramics, new alloys, and possibly unusual structural shapes, such as very uniform hollow glass shells for fusion target applications. High temperature acoustic levitation required for containerless processing has been demonstrated in low-g environments as well as in ground-based experiments. Future activities include continued development of the signals axis acoustic levitator.
Practical acoustic emission testing
2016-01-01
This book is intended for non-destructive testing (NDT) technicians who want to learn practical acoustic emission testing based on level 1 of ISO 9712 (Non-destructive testing – Qualification and certification of personnel) criteria. The essential aspects of ISO/DIS 18436-6 (Condition monitoring and diagnostics of machines – Requirements for training and certification of personnel, Part 6: Acoustic Emission) are explained, and readers can deepen their understanding with the help of practice exercises. This work presents the guiding principles of acoustic emission measurement, signal processing, algorithms for source location, measurement devices, applicability of testing methods, and measurement cases to support not only researchers in this field but also and especially NDT technicians.
Topological Acoustic Delay Line
Zhang, Zhiwang; Tian, Ye; Cheng, Ying; Wei, Qi; Liu, Xiaojun; Christensen, Johan
2018-03-01
Topological protected wave engineering in artificially structured media is at the frontier of ongoing metamaterials research that is inspired by quantum mechanics. Acoustic analogues of electronic topological insulators have recently led to a wealth of new opportunities in manipulating sound propagation with strikingly unconventional acoustic edge modes immune to backscattering. Earlier fabrications of topological insulators are characterized by an unreconfigurable geometry and a very narrow frequency response, which severely hinders the exploration and design of useful devices. Here we establish topologically protected sound in reconfigurable phononic crystals that can be switched on and off simply by rotating its three-legged "atoms" without altering the lattice structure. In particular, we engineer robust phase delay defects that take advantage of the ultrabroadband reflection-free sound propagation. Such topological delay lines serve as a paradigm in compact acoustic devices, interconnects, and electroacoustic integrated circuits.
Acoustic detection of pneumothorax
Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.
2003-04-01
This study aims at investigating the feasibility of using low-frequency (pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (ppneumothorax states (pPneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (pPneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.
Acoustics waves and oscillations
Sen, S.N.
2013-01-01
Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...
Vortex formation at the open end of an acoustic waveguide
Martinez Del Rio, Leon; Rendon, Pablo L.; Malaga, Carlos; Zenit, Roberto
2017-11-01
For high enough levels of acoustic pressure inside a cylindrical tube, a nonlinear mechanism is responsible for the formation of annular vortices at the open end of the tube, which results in energy loss. Higher sound pressure levels in the tube lead, in turn, to larger values of the acoustic velocity at the exit, and thus to higher Reynolds numbers. It has been observed [Buick et al., 2011] that, provided the magnitude of the acoustic velocity is large enough, two nonlinear regimes are possible: in the first regime, the vorticity appears only in the immediate vicinity of the tube; for higher velocities, vortex rings are formed at the open end of the tube and are advected outwards. We use a Lattice Boltzmann Method (LBM) to simulate the velocity and the pressure fields at the exit of the tube in 3D, with Reynolds numbers based on the acoustic boundary layer thickness 18 >Rδ > 1.8 . We also conduct experiments with phase-locked particle image velocimetry (PL-PIV) 2D within a range of 25.5 >Rδ > 10.2 . Experimental and numerical results are compared for a range of Womersley numbers. The effects of varying both the tube geometry and the end shape are addressed.
Acoustic Liners for Turbine Engines
Jones, Michael G (Inventor); Grady, Joseph E (Inventor); Kiser, James D. (Inventor); Miller, Christopher (Inventor); Heidmann, James D. (Inventor)
2016-01-01
An improved acoustic liner for turbine engines is disclosed. The acoustic liner may include a straight cell section including a plurality of cells with straight chambers. The acoustic liner may also include a bent cell section including one or more cells that are bent to extend chamber length without increasing the overall height of the acoustic liner by the entire chamber length. In some cases, holes are placed between cell chambers in addition to bending the cells, or instead of bending the cells.
Densitometry By Acoustic Levitation
Trinh, Eugene H.
1989-01-01
"Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.
Acoustic integrated extinction
Norris, Andrew N.
2015-01-01
The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122, 3206–3210. (doi:10.1121/1.2801546)) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we der...
Acoustic phenomena during boiling
International Nuclear Information System (INIS)
Dorofeev, B.M.
1985-01-01
Applied and theoretical significance of investigation into acoustic phenomena on boiling is discussed. Effect of spatial and time conditions on pressure vapour bubble has been elucidated. Collective effects were considered: acoustic interaction of bubbles, noise formation ion developed boiling, resonance and hydrodynamic autooscillations. Different methods for predicting heat transfer crisis using changes of accompanying noise characteristics were analysed. Principle peculiarities of generation mechanism of thermoacoustic autooscillations were analysed as well: formation of standing waves; change of two-phase medium contraction in a channel; relation of alternating pressure with boiling process as well as with instantaneous and local temperatures of heat transfer surface and liquid in a boundary layer
Shallow Water Acoustics Studies
2017-11-19
LE O CEAN RAPHIC I TITUTI Appli d Oc:ean Physics and E11gi1i,ering Depar1111,11t vember 9, 2017 Dr. Robert Headrick ffice of Naval Resear h, ode...UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT Applied Ocean Physics and Engineering Department...2015). [3] J.F. Lynch and A.E. Newhall, "Shallow water acoustics", book chapter in "Practical Underwater Acoustics," L. Bjorno, T. Neighbors, and D
Acoustic emission intrusion detector
International Nuclear Information System (INIS)
Carver, D.W.; Whittaker, J.W.
1980-01-01
An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal
Acoustic emission intrusion detector
International Nuclear Information System (INIS)
Carver, D.W.
1978-01-01
In order to improve the security of handling special nuclear materials at the Oak Ridge Y-12 Plant, a sensitive acoustic emission detector has been developed that will detect forcible entry through block or tile walls, concrete floors, or concrete/steel vault walls. A small, low-powered processor was designed to convert the output from a sensitive, crystal-type acoustic transducer to an alarm relay signal for use with a supervised alarm loop. The unit may be used to detect forcible entry through concrete, steel, block, tile, and/or glass
Mechel, Fridolin
2013-01-01
This book presents the theory of room acoustical fields and revises the Mirror Source Methods for practical computational use, emphasizing the wave character of acoustical fields. The presented higher methods include the concepts of “Mirror Point Sources” and “Corner sources which allow for an excellent approximation of complex room geometries and even equipped rooms. In contrast to classical description, this book extends the theory of sound fields describing them by their complex sound pressure and the particle velocity. This approach enables accurate descriptions of interference and absorption phenomena.
Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing
Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.
2009-01-01
Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in
Creep Damage Evaluation of Titanium Alloy Using Nonlinear Ultrasonic Lamb Waves
International Nuclear Information System (INIS)
Xiang Yan-Xun; Xuan Fu-Zhen; Deng Ming-Xi; Chen Hu; Chen Ding-Yue
2012-01-01
The creep damage in high temperature resistant titanium alloys Ti60 is measured using the nonlinear effect of an ultrasonic Lamb wave. The results show that the normalised acoustic nonlinearity of a Lamb wave exhibits a variation of the 'increase-decrease' tendency as a function of the creep damage. The influence of microstructure evolution on the nonlinear Lamb wave propagation has been analyzed based on metallographic studies, which reveal that the normalised acoustic nonlinearity increases due to a rising of the precipitation volume fraction and the dislocation density in the early stage, and it decreases as a combined result of dislocation change and micro-void initiation in the material. The nonlinear Lamb wave exhibits the potential for the assessment of the remaining creep life in metals
Positron-acoustic waves in an electron-positron plasma with an electron beam
International Nuclear Information System (INIS)
Nejoh, Y.N.
1996-01-01
The nonlinear wave structures of large-amplitude positron-acoustic waves are studied in an electron-positron plasma in the presence of an electron beam with finite temperature and hot electrons and positrons. The region where positron-acoustic waves exist is presented by analysing the structure of the pseudopotential. The region depends sensitively on the positron density, the positron temperature and the electron beam temperature. It is shown that the maximum amplitude of the wave decreases as the positron temperature increases, and the region of positron-acoustic waves spreads as the positron temperature increases. 11 refs., 5 figs
International Nuclear Information System (INIS)
Zhang, Shenwei; Qiu, Chunyin; Wang, Mudi; Ke, Manzhu; Liu, Zhengyou
2016-01-01
In this work, we study the acoustically mediated interaction forces among multiple well-separated spherical particles trapped in the same node or antinode plane of a standing wave. An analytical expression of the acoustic interaction force is derived, which is accurate even for the particles beyond the Rayleigh limit. Interestingly, the multi-particle system can be decomposed into a series of independent two-particle systems described by pairwise interactions. Each pairwise interaction is a long-range interaction, as characterized by a soft oscillatory attenuation (at the power exponent of n = −1 or −2). The vector additivity of the acoustic interaction force, which is not well expected considering the nonlinear nature of the acoustic radiation force, is greatly useful for exploring a system consisting of a large number of particles. The capability of self-organizing a big particle cluster can be anticipated through such acoustically controllable long-range interaction. (paper)
Variable-Position Acoustic Levitation
Barmatz, M. B.; Stoneburner, J. D.; Jacobi, N.; Wang, T. G.
1983-01-01
Method of acoustic levitation supports objects at positions other than acoustic nodes. Acoustic force is varied so it balances gravitational (or other) force, thereby maintaining object at any position within equilibrium range. Levitation method applicable to containerless processing. Such objects as table-tennis balls, hollow plastic spheres, and balsa-wood spheres levitated in laboratory by new method.
Fundamentals of Acoustics. Psychoacoustics and Hearing. Acoustical Measurements
Begault, Durand R.; Ahumada, Al (Technical Monitor)
1997-01-01
These are 3 chapters that will appear in a book titled "Building Acoustical Design", edited by Charles Salter. They are designed to introduce the reader to fundamental concepts of acoustics, particularly as they relate to the built environment. "Fundamentals of Acoustics" reviews basic concepts of sound waveform frequency, pressure, and phase. "Psychoacoustics and Hearing" discusses the human interpretation sound pressure as loudness, particularly as a function of frequency. "Acoustic Measurements" gives a simple overview of the time and frequency weightings for sound pressure measurements that are used in acoustical work.
Simulations of nonlinear continuous wave pressure fields in FOCUS
Zhao, Xiaofeng; Hamilton, Mark F.; McGough, Robert J.
2017-03-01
The Khokhlov - Zabolotskaya - Kuznetsov (KZK) equation is a parabolic approximation to the Westervelt equation that models the effects of diffraction, attenuation, and nonlinearity. Although the KZK equation is only valid in the far field of the paraxial region for mildly focused or unfocused transducers, the KZK equation is widely applied in medical ultrasound simulations. For a continuous wave input, the KZK equation is effectively modeled by the Bergen Code [J. Berntsen, Numerical Calculations of Finite Amplitude Sound Beams, in M. F. Hamilton and D. T. Blackstock, editors, Frontiers of Nonlinear Acoustics: Proceedings of 12th ISNA, Elsevier, 1990], which is a finite difference model that utilizes operator splitting. Similar C++ routines have been developed for FOCUS, the `Fast Object-Oriented C++ Ultrasound Simulator' (http://www.egr.msu.edu/˜fultras-web) to calculate nonlinear pressure fields generated by axisymmetric flat circular and spherically focused ultrasound transducers. This new routine complements an existing FOCUS program that models nonlinear ultrasound propagation with the angular spectrum approach [P. T. Christopher and K. J. Parker, J. Acoust. Soc. Am. 90, 488-499 (1991)]. Results obtained from these two nonlinear ultrasound simulation approaches are evaluated and compared for continuous wave linear simulations. The simulation results match closely in the farfield of the paraxial region, but the results differ in the nearfield. The nonlinear pressure field generated by a spherically focused transducer with a peak surface pressure of 0.2MPa radiating in a lossy medium with β = 3.5 is simulated, and the computation times are also evaluated. The nonlinear simulation results demonstrate acceptable agreement in the focal zone. These two related nonlinear simulation approaches are now included with FOCUS to enable convenient simulations of nonlinear pressure fields on desktop and laptop computers.
On Poisson Nonlinear Transformations
Directory of Open Access Journals (Sweden)
Nasir Ganikhodjaev
2014-01-01
Full Text Available We construct the family of Poisson nonlinear transformations defined on the countable sample space of nonnegative integers and investigate their trajectory behavior. We have proved that these nonlinear transformations are regular.
Improved acoustic levitation apparatus
Berge, L. H.; Johnson, J. L.; Oran, W. A.; Reiss, D. A.
1980-01-01
Concave driver and reflector enhance and shape levitation forces in acoustic resonance system. Single-mode standing-wave pattern is focused by ring element situated between driver and reflector. Concave surfaces increase levitating forces up to factor of 6 as opposed to conventional flat surfaces, making it possible to suspend heavier objects.
Crum, L. A.
1981-09-01
The primary thrust of this study was toward a more complete understanding of general aspects of acoustic cavitation. The effect of long-chain polymer additives on the cavitation threshold was investigated to determine if they reduced the acoustic cavitation threshold in a similar manner to the observed reduction in the cavitation index in hydrodynamic cavitation. Measurements were made of the acoustic cavitation threshold as a function of polymer concentration for additives such as guar gum and polyethelene oxide. The measurements were also made as a function of dissolved gas concentration, surface tension and viscosity. It was determined that there was a significant increase in the acoustic cavitation threshold for increased concentrations of the polymer additives (measurable effects could be obtained for concentrations as low as a few parts per million). One would normally expect that an additive that reduces surface tension to decrease the pressure required to cause a cavity to grow and thus these additives, at first thought, should reduce the threshold. However, even in the hydrodynamic case, the threshold was increased. In both of the hydrodynamic cases considered, the explanation for the increased threshold was given in terms of changed fluid dynamics rather than changed physical properties of the fluid.
Acoustic Neuroma Educational Video
Full Text Available ... Cumming, GA 30041 770-205-8211 info@ANAUSA.org The world’s #1 acoustic neuroma resource Click to ... Cumming, GA 30041 770-205-8211 info@ANAUSA.org About ANA Mission, Vision & Values Leadership & Staff Annual ...
DEFF Research Database (Denmark)
Elberling, C; Parbo, J; Johnsen, N J
1985-01-01
Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...
DEFF Research Database (Denmark)
Harrison, Adrian Paul; Danneskiold-Samsøe, Bente; Bartels, Else Marie
2013-01-01
Muscle sound gives a local picture of muscles involved in a particular movement and is independent of electrical signals between nerve and muscle. Sound recording (acoustic myography) is a well-known noninvasive technique that has suffered from not being easily applicable, as well as not being able...
DEFF Research Database (Denmark)
Dühring, Maria Bayard
The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...
Sitters, G.; Kamsma, D.; Thalhammer, G.; Ritsch-Marte, M.; Peterman, E.J.G.; Wuite, G.J.L.
2015-01-01
Force spectroscopy has become an indispensable tool to unravel the structural and mechanochemical properties of biomolecules. Here we extend the force spectroscopy toolbox with an acoustic manipulation device that can exert forces from subpiconewtons to hundreds of piconewtons on thousands of
Underwater Acoustic Networking Techniques
Otnes, Roald; Casari, Paolo; Goetz, Michael; Husøy, Thor; Nissen, Ivor; Rimstad, Knut; van Walree, Paul; Zorzi, Michele
2012-01-01
This literature study presents an overview of underwater acoustic networking. It provides a background and describes the state of the art of all networking facets that are relevant for underwater applications. This report serves both as an introduction to the subject and as a summary of existing protocols, providing support and inspiration for the development of network architectures.
Zijlstra, A.G.
2011-01-01
Merely the presence of compressible entities, known as bubbles, greatly enriches the physical phenomena encountered when introducing ultrasound in a liquid. Mediated by the response of these bubbles, the otherwise diffuse and relatively low energy density of the acoustic field can induce strong,
Moore, Keegan J.; Bunyan, Jonathan; Tawfick, Sameh; Gendelman, Oleg V.; Li, Shuangbao; Leamy, Michael; Vakakis, Alexander F.
2018-01-01
In linear time-invariant dynamical and acoustical systems, reciprocity holds by the Onsager-Casimir principle of microscopic reversibility, and this can be broken only by odd external biases, nonlinearities, or time-dependent properties. A concept is proposed in this work for breaking dynamic reciprocity based on irreversible nonlinear energy transfers from large to small scales in a system with nonlinear hierarchical internal structure, asymmetry, and intentional strong stiffness nonlinearity. The resulting nonreciprocal large-to-small scale energy transfers mimic analogous nonlinear energy transfer cascades that occur in nature (e.g., in turbulent flows), and are caused by the strong frequency-energy dependence of the essentially nonlinear small-scale components of the system considered. The theoretical part of this work is mainly based on action-angle transformations, followed by direct numerical simulations of the resulting system of nonlinear coupled oscillators. The experimental part considers a system with two scales—a linear large-scale oscillator coupled to a small scale by a nonlinear spring—and validates the theoretical findings demonstrating nonreciprocal large-to-small scale energy transfer. The proposed study promotes a paradigm for designing nonreciprocal acoustic materials harnessing strong nonlinearity, which in a future application will be implemented in designing lattices incorporating nonlinear hierarchical internal structures, asymmetry, and scale mixing.
Select Internet Resources on Acoustics
Directory of Open Access Journals (Sweden)
Angela R. Davis
2016-12-01
Full Text Available Merriam-Webster (2016 defines acoustics as, “a science that deals with the production, control, transmission, reception, and effects of sounds.” According to Rossing (2014, the study of acoustics began in ancient Greece with Pythagoras’ study of vibrating strings on musical instruments. Since those early beginnings, famous scientists including Rayleigh, Alexander Graham Bell, and Thomas Edison, have helped expand the field of acoustics to include architectural, physical, engineering, structural, underwater, physiological and psychological, musical acoustics, and speech. Acoustics is a highly interdisciplinary field and researchers may need resources from physics, medicine, and engineering to understand all aspects of their research.
Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong
2015-01-01
This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.
Radiative acoustic investigation of metals in the area of structural phase transition
International Nuclear Information System (INIS)
Kalinichenko, A.I.; Popov, G.F.
1989-01-01
Consideration is given to results of experimental investigations of temperature dependences of Grueneisen parameter (GP) and sound velocity for alloys with the effect of shape memory (Cu-Al-Ni and Ni-Ti) and gadolinium in the region of their structural phase transformations. Effect of thermal and spatial GP nonlinearity on the type of excited acoustic wave, as well as possibility of determining function of GP dependence with respect to nonlinear thermoacoustic response of irradiated substance are discussed
Pressure potential and stability analysis in an acoustical noncontact transportation
Li, J.; Liu, C. J.; Zhang, W. J.
2017-01-01
Near field acoustic traveling wave is one of the most popular principles in noncontact manipulations and transportations. The stability behavior is a key factor in the industrial applications of acoustical noncontact transportation. We present here an in-depth analysis of the transportation stability of a planar object levitated in near field acoustic traveling waves. To more accurately describe the pressure distributions on the radiation surface, a 3D nonlinear traveling wave model is presented. A closed form solution is derived based on the pressure potential to quantitatively calculate the restoring forces and moments under small disturbances. The physical explanations of the effects of fluid inertia and the effects of non-uniform pressure distributions are provided in detail. It is found that a vibration rail with tapered cross section provides more stable transportation than a rail with rectangular cross section. The present study sheds light on the issue of quantitative evaluation of stability in acoustic traveling waves and proposes three main factors that influence the stability: (a) vibration shape, (b) pressure distribution and (c) restoring force/moment. It helps to provide a better understanding of the physics behind the near field acoustic transportation and provide useful design and optimization tools for industrial applications.
Systematic Error of Acoustic Particle Image Velocimetry and Its Correction
Directory of Open Access Journals (Sweden)
Mickiewicz Witold
2014-08-01
Full Text Available Particle Image Velocimetry is getting more and more often the method of choice not only for visualization of turbulent mass flows in fluid mechanics, but also in linear and non-linear acoustics for non-intrusive visualization of acoustic particle velocity. Particle Image Velocimetry with low sampling rate (about 15Hz can be applied to visualize the acoustic field using the acquisition synchronized to the excitation signal. Such phase-locked PIV technique is described and used in experiments presented in the paper. The main goal of research was to propose a model of PIV systematic error due to non-zero time interval between acquisitions of two images of the examined sound field seeded with tracer particles, what affects the measurement of complex acoustic signals. Usefulness of the presented model is confirmed experimentally. The correction procedure, based on the proposed model, applied to measurement data increases the accuracy of acoustic particle velocity field visualization and creates new possibilities in observation of sound fields excited with multi-tonal or band-limited noise signals.
Melde, Kai; Mark, Andrew G; Qiu, Tian; Fischer, Peer
2016-09-22
Holographic techniques are fundamental to applications such as volumetric displays, high-density data storage and optical tweezers that require spatial control of intricate optical or acoustic fields within a three-dimensional volume. The basis of holography is spatial storage of the phase and/or amplitude profile of the desired wavefront in a manner that allows that wavefront to be reconstructed by interference when the hologram is illuminated with a suitable coherent source. Modern computer-generated holography skips the process of recording a hologram from a physical scene, and instead calculates the required phase profile before rendering it for reconstruction. In ultrasound applications, the phase profile is typically generated by discrete and independently driven ultrasound sources; however, these can only be used in small numbers, which limits the complexity or degrees of freedom that can be attained in the wavefront. Here we introduce monolithic acoustic holograms, which can reconstruct diffraction-limited acoustic pressure fields and thus arbitrary ultrasound beams. We use rapid fabrication to craft the holograms and achieve reconstruction degrees of freedom two orders of magnitude higher than commercial phased array sources. The technique is inexpensive, appropriate for both transmission and reflection elements, and scales well to higher information content, larger aperture size and higher power. The complex three-dimensional pressure and phase distributions produced by these acoustic holograms allow us to demonstrate new approaches to controlled ultrasonic manipulation of solids in water, and of liquids and solids in air. We expect that acoustic holograms will enable new capabilities in beam-steering and the contactless transfer of power, improve medical imaging, and drive new applications of ultrasound.
Acoustic field modulation in regenerators
Hu, J. Y.; Wang, W.; Luo, E. C.; Chen, Y. Y.
2016-12-01
The regenerator is a key component that transfers energy between heat and work. The conversion efficiency is significantly influenced by the acoustic field in the regenerator. Much effort has been spent to quantitatively determine this influence, but few comprehensive experimental verifications have been performed because of difficulties in modulating and measuring the acoustic field. In this paper, a method requiring two compressors is introduced and theoretically investigated that achieves acoustic field modulation in the regenerator. One compressor outputs the acoustic power for the regenerator; the other acts as a phase shifter. A RC load dissipates the acoustic power out of both the regenerator and the latter compressor. The acoustic field can be modulated by adjusting the current in the two compressors and opening the RC load. The acoustic field is measured with pressure sensors instead of flow-field imaging equipment, thereby greatly simplifying the experiment.
Controlling sound with acoustic metamaterials
DEFF Research Database (Denmark)
Cummer, Steven A. ; Christensen, Johan; Alù, Andrea
2016-01-01
Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales....... The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak objects from incident acoustic energy. Active acoustic metamaterials use external control to create......-scale metamaterial structures and converting laboratory experiments into useful devices. In this Review, we outline the designs and properties of materials with unusual acoustic parameters (for example, negative refractive index), discuss examples of extreme manipulation of sound and, finally, provide an overview...
Bubble nonlinear dynamics and stimulated scattering process
Jie, Shi; De-Sen, Yang; Sheng-Guo, Shi; Bo, Hu; Hao-Yang, Zhang; Shi-Yong, Hu
2016-02-01
A complete understanding of the bubble dynamics is deemed necessary in order to achieve their full potential applications in industry and medicine. For this purpose it is first needed to expand our knowledge of a single bubble behavior under different possible conditions including the frequency and pressure variations of the sound field. In addition, stimulated scattering of sound on a bubble is a special effect in sound field, and its characteristics are associated with bubble oscillation mode. A bubble in liquid can be considered as a representative example of nonlinear dynamical system theory with its resonance, and its dynamics characteristics can be described by the Keller-Miksis equation. The nonlinear dynamics of an acoustically excited gas bubble in water is investigated by using theoretical and numerical analysis methods. Our results show its strongly nonlinear behavior with respect to the pressure amplitude and excitation frequency as the control parameters, and give an intuitive insight into stimulated sound scattering on a bubble. It is seen that the stimulated sound scattering is different from common dynamical behaviors, such as bifurcation and chaos, which is the result of the nonlinear resonance of a bubble under the excitation of a high amplitude acoustic sound wave essentially. The numerical analysis results show that the threshold of stimulated sound scattering is smaller than those of bifurcation and chaos in the common condition. Project supported by the Program for Changjiang Scholars and Innovative Research Team in University, China (Grant No. IRT1228) and the Young Scientists Fund of the National Natural Science Foundation of China (Grant Nos. 11204050 and 11204049).
Analysis of factors influencing fire damage to concrete using nonlinear resonance vibration method
Energy Technology Data Exchange (ETDEWEB)
Park, Gang Kyu; Park, Sun Jong; Kwak, Hyo Gyoung [Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, KAIST, Daejeon (Korea, Republic of); Yim, Hong Jae [Dept. of Construction and Disaster Prevention Engineering, Kyungpook National University, Sangju (Korea, Republic of)
2015-04-15
In this study, the effects of different mix proportions and fire scenarios (exposure temperatures and post-fire-curing periods) on fire-damaged concrete were analyzed using a nonlinear resonance vibration method based on nonlinear acoustics. The hysteretic nonlinearity parameter was obtained, which can sensitively reflect the damage level of fire-damaged concrete. In addition, a splitting tensile strength test was performed on each fire-damaged specimen to evaluate the residual property. Using the results, a prediction model for estimating the residual strength of fire-damaged concrete was proposed on the basis of the correlation between the hysteretic nonlinearity parameter and the ratio of splitting tensile strength.
Phase-space topography characterization of nonlinear ultrasound waveforms.
Dehghan-Niri, Ehsan; Al-Beer, Helem
2018-03-01
Fundamental understanding of ultrasound interaction with material discontinuities having closed interfaces has many engineering applications such as nondestructive evaluation of defects like kissing bonds and cracks in critical structural and mechanical components. In this paper, to analyze the acoustic field nonlinearities due to defects with closed interfaces, the use of a common technique in nonlinear physics, based on a phase-space topography construction of ultrasound waveform, is proposed. The central idea is to complement the "time" and "frequency" domain analyses with the "phase-space" domain analysis of nonlinear ultrasound waveforms. A nonlinear time series method known as pseudo phase-space topography construction is used to construct equivalent phase-space portrait of measured ultrasound waveforms. Several nonlinear models are considered to numerically simulate nonlinear ultrasound waveforms. The phase-space response of the simulated waveforms is shown to provide different topographic information, while the frequency domain shows similar spectral behavior. Thus, model classification can be substantially enhanced in the phase-space domain. Experimental results on high strength aluminum samples show that the phase-space transformation provides a unique detection and classification capabilities. The Poincaré map of the phase-space domain is also used to better understand the nonlinear behavior of ultrasound waveforms. It is shown that the analysis of ultrasound nonlinearities is more convenient and informative in the phase-space domain than in the frequency domain. Copyright © 2017 Elsevier B.V. All rights reserved.
Hanamura, Eiichi; Yamanaka, Akio
2007-01-01
This graduate-level textbook gives an introductory overview of the fundamentals of quantum nonlinear optics. Based on the quantum theory of radiation, Quantum Nonlinear Optics incorporates the exciting developments in novel nonlinear responses of materials (plus laser oscillation and superradiance) developed over the past decade. It deals with the organization of radiation field, interaction between electronic system and radiation field, statistics of light, mutual manipulation of light and matter, laser oscillation, dynamics of light, nonlinear optical response, and nonlinear spectroscopy, as well as ultrashort and ultrastrong laser pulse. Also considered are Q-switching, mode locking and pulse compression. Experimental and theoretical aspects are intertwined throughout.
Nonlinear dynamics and complexity
Luo, Albert; Fu, Xilin
2014-01-01
This important collection presents recent advances in nonlinear dynamics including analytical solutions, chaos in Hamiltonian systems, time-delay, uncertainty, and bio-network dynamics. Nonlinear Dynamics and Complexity equips readers to appreciate this increasingly main-stream approach to understanding complex phenomena in nonlinear systems as they are examined in a broad array of disciplines. The book facilitates a better understanding of the mechanisms and phenomena in nonlinear dynamics and develops the corresponding mathematical theory to apply nonlinear design to practical engineering.
Merkel, A; Tournat, V; Gusev, V
2014-08-01
We report the experimental observation of the gravity-induced asymmetry for the nonlinear transformation of acoustic waves in a noncohesive granular phononic crystal. Because of the gravity, the contact precompression increases with depth inducing space variations of not only the linear and nonlinear elastic moduli but also of the acoustic wave dissipation. We show experimentally and explain theoretically that, in contrast to symmetric propagation of linear waves, the amplitude of the nonlinearly self-demodulated wave depends on whether the propagation of the waves is in the direction of the gravity or in the opposite direction. Among the observed nonlinear processes, we report frequency mixing of the two transverse-rotational modes belonging to the optical band of vibrations and propagating with negative phase velocities, which results in the excitation of a longitudinal wave belonging to the acoustic band of vibrations and propagating with positive phase velocity. We show that the measurements of the gravity-induced asymmetry in the nonlinear acoustic phenomena can be used to compare the in-depth distributions of the contact nonlinearity and of acoustic absorption.
Distributed nonlinear optical response
DEFF Research Database (Denmark)
Nikolov, Nikola Ivanov
2005-01-01
of bound states of out of phase bright solitons and dark solitons. Also, the newly introduced analogy between the nonlocal cubic nonlinear and the quadratic nonlinear media, presented in paper B and Chapter 3 is discussed. In particular it supplies intuitive physical meaning of the formation of solitons...... in quadratic nonlinear media. In the second part of the report (Chapter 4), the possibility to obtain light with ultrabroad spectrum due to the interplay of many nonlinear effects based on cubic nonlinearity is investigated thoroughly. The contribution of stimulated Raman scattering, a delayed nonlinear...... a modified nonlinear Schroedinger model equation. Chapter 4 and papers D and E are dedicated to this part of the research....
Nonextensive dust acoustic waves in a charge varying dusty plasma
Bacha, Mustapha; Tribeche, Mouloud
2012-01-01
Our recent analysis on nonlinear nonextensive dust-acoustic waves (DA) [Amour and Tribeche in Phys. Plasmas 17:063702, 2010] is extended to include self-consistent nonadiabatic grain charge fluctuation. The appropriate nonextensive electron charging current is rederived based on the orbit-limited motion theory. Our results reveal that the amplitude, strength and nature of the nonlinear DA waves (solitons and shocks) are extremely sensitive to the degree of ion nonextensivity. Stronger is the electron correlation, more important is the charge variation induced nonlinear wave damping. The anomalous dissipation effects may prevail over that dispersion as the electrons evolve far away from their Maxwellian equilibrium. Our investigation may be of wide relevance to astronomers and space scientists working on interstellar dusty plasmas where nonthermal distributions are turning out to be a very common and characteristic feature.
Novak, A.; Simon, L.; Lotton, P.
2018-04-01
Mechanical transducers, such as shakers, loudspeakers and compression drivers that are used as excitation devices to excite acoustical or mechanical nonlinear systems under test are imperfect. Due to their nonlinear behaviour, unwanted contributions appear at their output besides the wanted part of the signal. Since these devices are used to study nonlinear systems, it should be required to measure properly the systems under test by overcoming the influence of the nonlinear excitation device. In this paper, a simple method that corrects distorted output signal of the excitation device by means of predistortion of its input signal is presented. A periodic signal is applied to the input of the excitation device and, from analysing the output signal of the device, the input signal is modified in such a way that the undesirable spectral components in the output of the excitation device are cancelled out after few iterations of real-time processing. The experimental results provided on an electrodynamic shaker show that the spectral purity of the generated acceleration output approaches 100 dB after few iterations (1 s). This output signal, applied to the system under test, is thus cleaned from the undesirable components produced by the excitation device; this is an important condition to ensure a correct measurement of the nonlinear system under test.
Education in acoustics in Argentina
Miyara, Federico
2002-11-01
Over the last decades, education in acoustics (EA) in Argentina has experienced ups and downs due to economic and political issues interfering with long term projects. Unlike other countries, like Chile, where EA has reached maturity in spite of the acoustical industry having shown little development, Argentina has several well-established manufacturers of acoustic materials and equipment but no specific career with a major in acoustics. At the university level, acoustics is taught as a complementary--often elective--course for careers such as architecture, communication engineering, or music. In spite of this there are several research centers with programs covering environmental and community noise, effects of noise on man, acoustic signal processing, musical acoustics and acoustic emission, and several national and international meetings are held each year in which results are communicated and discussed. Several books on a variety of topics such as sound system, architectural acoustics, and noise control have been published as well. Another chapter in EA is technical and vocational education, ranging between secondary and postsecondary levels, with technical training on sound system operation or design. Over the last years there have been several attempts to implement master degrees in acoustics or audio engineering, with little or no success.
Acoustic energy harvesting based on a planar acoustic metamaterial
Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine
2016-06-01
We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.
Flat acoustic lens by acoustic grating with curled slits
Peng, Pai
2014-10-01
We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry-Perot resonance.
Nonlinear dynamics of zigzag molecular chains (in Russian)
DEFF Research Database (Denmark)
Savin, A. V.; Manevitsch, L. I.; Christiansen, Peter Leth
1999-01-01
models (two-dimensional alpha-spiral, polyethylene transzigzag backbone, and the zigzag chain of hydrogen bonds) shows that the zigzag structure essentially limits the soliton dynamics to finite, relatively narrow, supersonic soliton velocity intervals and may also result in that several acoustic soliton......Nonlinear, collective, soliton type excitations in zigzag molecular chains are analyzed. It is shown that the nonlinear dynamics of a chain dramatically changes in passing from the one-dimensional linear chain to the more realistic planar zigzag model-due, in particular, to the geometry...
Quantum acoustics with superconducting qubits
Chu, Yiwen
2017-04-01
The ability to engineer and manipulate different types of quantum mechanical objects allows us to take advantage of their unique properties and create useful hybrid technologies. Thus far, complex quantum states and exquisite quantum control have been demonstrated in systems ranging from trapped ions to superconducting resonators. Recently, there have been many efforts to extend these demonstrations to the motion of complex, macroscopic objects. These mechanical objects have important applications as quantum memories or transducers for measuring and connecting different types of quantum systems. In particular, there have been a few experiments that couple motion to nonlinear quantum objects such as superconducting qubits. This opens up the possibility of creating, storing, and manipulating non-Gaussian quantum states in mechanical degrees of freedom. However, before sophisticated quantum control of mechanical motion can be achieved, we must realize systems with long coherence times while maintaining a sufficient interaction strength. These systems should be implemented in a simple and robust manner that allows for increasing complexity and scalability in the future. In this talk, I will describe our recent experiments demonstrating a high frequency bulk acoustic wave resonator that is strongly coupled to a superconducting qubit using piezoelectric transduction. In contrast to previous experiments with qubit-mechanical systems, our device requires only simple fabrication methods, extends coherence times to many microseconds, and provides controllable access to a multitude of phonon modes. We use this system to demonstrate basic quantum operations on the coupled qubit-phonon system. Straightforward improvements to the current device will allow for advanced protocols analogous to what has been shown in optical and microwave resonators, resulting in a novel resource for implementing hybrid quantum technologies.
Directory of Open Access Journals (Sweden)
Gordon Hayward
2016-12-01
Full Text Available An acoustic prion assay has been demonstrated for sheep brain samples. Only five false positives and no false negatives were observed in a test of 45 positive and 45 negative samples. The acoustic prion sensor was constructed using a thickness shear mode quartz resonator coated with a covalently bound recombinant prion protein. The characteristic indicator of a scrapie infected sheep brain sample was an observed shoulder in the frequency decrease in response to a sample.The response of the sensor aligns with a conformational shift in the surface protein and with the propagation mechanism of the disease. This alignment is evident in the response timing and shape, dependence on concentration, cross species behaviour and impact of blood plasma. This alignment is far from sufficient to prove the mechanism of the sensor but it does offer the possibility of a rapid and inexpensive additional tool to explore prion disease. Keywords: Prions, Thickness shear mode quartz sensor
Acoustic heating produced in the thermoviscous flow of a Bingham plastic
Perelomova, Anna
2011-02-01
This study is devoted to the instantaneous acoustic heating of a Bingham plastic. The model of the Bingham plastic's viscous stress tensor includes the yield stress along with the shear viscosity, which differentiates a Bingham plastic from a viscous Newtonian fluid. A special linear combination of the conservation equations in differential form makes it possible to reduce all acoustic terms in the linear part of of the final equation governing acoustic heating, and to retain those belonging to the thermal mode. The nonlinear terms of the final equation are a result of interaction between sounds and the thermal mode. In the field of intense sound, the resulting nonlinear acoustic terms form a driving force for the heating. The final governing dynamic equation of the thermal mode is valid in a weakly nonlinear flow. It is instantaneous, and does not imply that sounds be periodic. The equations governing the dynamics of both sounds and the thermal mode depend on sign of the shear rate. An example of the propagation of a bipolar initially acoustic pulse and the evolution of the heating induced by it is illustrated and discussed.
Zoladz, T.; Earhart, E.; Fiorucci, T.
1995-01-01
Utilizing high-frequency data from a highly instrumented rotor assembly, seeded bearing defect signatures are characterized using both conventional linear approaches, such as power spectral density analysis, and recently developed nonlinear techniques such as bicoherence analysis. Traditional low-frequency (less than 20 kHz) analysis and high-frequency envelope analysis of both accelerometer and acoustic emission data are used to recover characteristic bearing distress information buried deeply in acquired data. The successful coupling of newly developed nonlinear signal analysis with recovered wideband envelope data from accelerometers and acoustic emission sensors is the innovative focus of this research.
Pevernagie, Dirk; Aarts, Ronald M; De Meyer, Micheline
2010-04-01
Snoring is a prevalent disorder affecting 20-40% of the general population. The mechanism of snoring is vibration of anatomical structures in the pharyngeal airway. Flutter of the soft palate accounts for the harsh aspect of the snoring sound. Natural or drug-induced sleep is required for its appearance. Snoring is subject to many influences such as body position, sleep stage, route of breathing and the presence or absence of sleep-disordered breathing. Its presentation may be variable within or between nights. While snoring is generally perceived as a social nuisance, rating of its noisiness is subjective and, therefore, inconsistent. Objective assessment of snoring is important to evaluate the effect of treatment interventions. Moreover, snoring carries information relating to the site and degree of obstruction of the upper airway. If evidence for monolevel snoring at the site of the soft palate is provided, the patient may benefit from palatal surgery. These considerations have inspired researchers to scrutinize the acoustic characteristics of snoring events. Similarly to speech, snoring is produced in the vocal tract. Because of this analogy, existing techniques for speech analysis have been applied to evaluate snoring sounds. It appears that the pitch of the snoring sound is in the low-frequency range (noise-like', and has scattered energy content in the higher spectral sub-bands (>500 Hz). To evaluate acoustic properties of snoring, sleep nasendoscopy is often performed. Recent evidence suggests that the acoustic quality of snoring is markedly different in drug-induced sleep as compared with natural sleep. Most often, palatal surgery alters sound characteristics of snoring, but is no cure for this disorder. It is uncertain whether the perceived improvement after palatal surgery, as judged by the bed partner, is due to an altered sound spectrum. Whether some acoustic aspects of snoring, such as changes in pitch, have predictive value for the presence of
2017-09-25
Technology Transfer at (401) 832-1511. DISTRIBUTION STATEMENT Approved for Public Release Distribution is unlimited Attorney Docket No...in the enclosure through osmosis. Valves open at a specified time after the liquid injection to free flood between the enclosure and the...the timing of the salt jets and the free-flooding valves enables a repeatable Attorney Docket No. 300070 4 of 14 acoustic pulse at low
Anisotropy of acoustic properties in paratellurite
International Nuclear Information System (INIS)
Parygin, Vladimir N.
1996-01-01
One of the peculiarities of the TeO 2 crystal consists of its strong acoustic anisotropy. This anisotropy demonstrates itself by acoustic energy walk-off and anisotropic distortion of an acoustic beam. Four constants completely characterise the acoustic anisotropy of the medium. In this paper these constants are calculated for various directions of the acoustic beam in crystal. (authors)
Canada Basin Acoustic Propagation Experiment (CANAPE)
2015-09-30
acoustic communications, acoustic navigation, or acoustic remote sensing of the ocean interior . RELATED PROJECTS The 2015 CANAPE pilot study was a...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Canada Basin Acoustic Propagation Experiment (CANAPE...ocean structure. Changes in sea ice and the water column affect both acoustic propagation and ambient noise. This implies that what was learned
Acoustically enhanced heat transport
Energy Technology Data Exchange (ETDEWEB)
Ang, Kar M.; Hung, Yew Mun; Tan, Ming K., E-mail: tan.ming.kwang@monash.edu [School of Engineering, Monash University Malaysia, 47500 Bandar Sunway, Selangor (Malaysia); Yeo, Leslie Y. [Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3001 (Australia); Friend, James R. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093 (United States)
2016-01-15
We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10{sup 6} Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξ{sub s} ∼ 10{sup −9} m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξ{sub s} ∼ 10{sup −8} m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10{sup −8} m with 10{sup 6} Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.
Anand, V T; Byrnes, D P; Walby, A P; Kerr, A G
1993-10-01
This article reviews 12 patients with bilateral acoustic neuromas. The sex incidence was equal and the mean age at diagnosis was 26.2 years. The family history was positive in nine of the patients. Five patients have had incomplete surgical removal of acoustic neuromas on both sides. Two of them are completely deaf and the other three have severe sensorineural hearing loss in one ear and no hearing in the other ear. In five patients the tumour on one side has been operated on and the other side is being observed with at least short-term preservation of good hearing. The remaining two patients died of intra-cranial complications, one of them post-operatively. Four patients developed facial palsy immediately following surgery and one developed facial weakness 6 months after surgery. Guidelines are discussed for the care of these patients including the timing of surgery and alternative treatment options (observation, radio-surgery and chemotherapy). This is essentially a group of young individuals who have had multiple operations for bilateral acoustic tumours and associated manifestations and for whom the disease and the sequelae of treatment can be tragic.
Nonlinear resonance ultrasonic vibrations in Czochralski-silicon wafers
Ostapenko, S.; Tarasov, I.
2000-04-01
A resonance effect of generation of subharmonic acoustic vibrations is observed in as-grown, oxidized, and epitaxial silicon wafers. Ultrasonic vibrations were generated into a standard 200 mm Czochralski-silicon (Cz-Si) wafer using a circular ultrasound transducer with major frequency of the radial vibrations at about 26 kHz. By tuning frequency (f) of the transducer within a resonance curve, we observed a generation of intense f/2 subharmonic acoustic mode assigned as a "whistle." The whistle mode has a threshold amplitude behavior and narrow frequency band. The whistle is attributed to a nonlinear acoustic vibration of a silicon plate. It is demonstrated that characteristics of the whistle mode are sensitive to internal stress and can be used for quality control and in-line diagnostics of oxidized and epitaxial Cz-Si wafers.
Directory of Open Access Journals (Sweden)
S. S. Ghosh
2004-01-01
Full Text Available The presence of dynamic, large amplitude solitary waves in the auroral regions of space is well known. Since their velocities are of the order of the ion acoustic speed, they may well be considered as being generated from the nonlinear evolution of ion acoustic waves. However, they do not show the expected width-amplitude correlation for K-dV solitons. Recent POLAR observations have actually revealed that the low altitude rarefactive ion acoustic solitary waves are associated with an increase in the width with increasing amplitude. This indicates that a weakly nonlinear theory is not appropriate to describe the solitary structures in the auroral regions. In the present work, a fully nonlinear analysis based on Sagdeev pseudopotential technique has been adopted for both parallel and oblique propagation of rarefactive solitary waves in a two electron temperature multi-ion plasma. The large amplitude solutions have consistently shown an increase in the width with increasing amplitude. The width-amplitude variation profile of obliquely propagating rarefactive solitary waves in a magnetized plasma have been compared with the recent POLAR observations. The width-amplitude variation pattern is found to fit well with the analytical results. It indicates that a fully nonlinear theory of ion acoustic solitary waves may well explain the observed anomalous width variations of large amplitude structures in the auroral region.
High-Frequency Seafloor Acoustics
Jackson, Darrell R
2007-01-01
High-Frequency Seafloor Acoustics is the first book in a new series sponsored by the Office of Naval Research on the latest research in underwater acoustics. This exciting new title provides ready access to experimental data, theory, and models relevant to high-frequency seafloor acoustics and will be of interest to sonar engineers and researchers working in underwater acoustics. The physical characteristics of the seafloor affecting acoustic propagation and scattering are covered, including physical and geoacoustic properties and surface roughness. Current theories for acoustic propagation in sediments are presented along with corresponding models for reflection, scattering, and seafloor penetration. The main text is backed up by an extensive bibliography and technical appendices.
Fundamentals of Shallow Water Acoustics
Katsnelson, Boris; Lynch, James
2012-01-01
Shallow water acoustics (SWA), the study of how low and medium frequency sound propagates and scatters on the continental shelves of the world's oceans, has both technical interest and a large number of practical applications. Technically, shallow water poses an interesting medium for the study of acoustic scattering, inverse theory, and propagation physics in a complicated oceanic waveguide. Practically, shallow water acoustics has interest for geophysical exploration, marine mammal studies, and naval applications. Additionally, one notes the very interdisciplinary nature of shallow water acoustics, including acoustical physics, physical oceanography, marine geology, and marine biology. In this specialized volume, the authors, all of whom have extensive at-sea experience in U.S. and Russian research efforts, have tried to summarize the main experimental, theoretical, and computational results in shallow water acoustics, with an emphasis on providing physical insight into the topics presented.
Nonlinear piezoelectricity in PZT ceramics for generating ultrasonic phase conjugate waves
Yamamoto; Kokubo; Sakai; Takagi
2000-03-01
We have succeeded in the generation of acoustic phase conjugate waves with nonlinear PZT piezoelectric ceramics and applied them to ultrasonic imaging systems. Our aim is to make a phase conjugator with 100% efficiency. For this purpose, it is important to clarify the mechanism of acoustic phase conjugation through nonlinear piezoelectricity. The process is explained by the parametric interaction via the third-order nonlinear piezoelectricity between the incident acoustic wave at angular frequency omega and the pump electric field at 2 omega. We solved the coupling equations including the third-ordered nonlinear piezoelectricity and theoretically derived the amplitude efficiency of the acoustic phase conjugation. We compared the efficiencies between the theoretical and experimental values for PZT ceramics with eight different compositions. Pb[(Zn1/3Nb2/3)(1 - x)Tix]O3 (X = 0.09, PZNT91/9) piezoelectric single crystals have been investigated for high-performance ultrasonic transducer application, because these have large piezoelectric constants, high electrical-mechanical coupling factors and high dielectric constants. We found that they have third-order nonlinear piezoelectric constants much larger than PZT and are hopeful that the material as a phase conjugator has over 100% efficiency.
Non-linear time reversal ultrasonic pseudo-tomography
Czech Academy of Sciences Publication Activity Database
Převorovský, Zdeněk; Vejvodová, Šárka; Krofta, Josef; Převorovský, David
2011-01-01
Roč. 6, 3/4 (2011), s. 206-213 ISSN 1741-8410. [NDT in Progress. Praha, 05.11.2007-07.11.2007] R&D Projects: GA MPO(CZ) FR-TI1/274 Institutional research plan: CEZ:AV0Z20760514 Keywords : NDT * nonlinear elastic wave spectroscopy * time reversal mirrors * ultrasonic pseudo-tomography Subject RIV: BI - Acoustics http://www.inderscience.com/offer.php?id=43216
Experiments on stress dependent borehole acoustic waves.
Hsu, Chaur-Jian; Kane, Michael R; Winkler, Kenneth; Wang, Canyun; Johnson, David Linton
2011-10-01
In the laboratory setup, a borehole traverses a dry sandstone formation, which is subjected to a controlled uniaxial stress in the direction perpendicular to the borehole axis. Measurements are made in a single loading-unloading stress cycle from zero to 10 MPa and then back down to zero stress. The applied stress and the presence of the borehole induce anisotropy in the bulk of the material and stress concentration around the borehole, both azimuthally and radially. Acoustic waves are generated and detected in the water-filled borehole, including compressional and shear headwaves, as well as modes of monopole, dipole, quadrupole, and higher order azimuthal symmetries. The linear and non-linear elastic parameters of the formation material are independently quantified, and utilized in conjunction with elastic theories to predict the characteristics of various borehole waves at zero and finite stress conditions. For example, an analytic theory is developed which is successfully used to estimate the changes of monopole tube mode at low frequency resulted from uniaxial stress, utilizing the measured material third order elasticity parameters. Comparisons between various measurements as well as that between experiments and theories are also presented. © 2011 Acoustical Society of America
Method and system for generating a beam of acoustic energy from a borehole, and applications thereof
Johnson, Paul A [Santa Fe, NM; Ten Cate, James A [Los Alamos, NM; Guyer, Robert [Reno, NV; Le Bas, Pierre-Yves [Los Alamos, NM; Vu, Cung [Houston, TX; Nihei, Kurt [Oakland, CA; Schmitt, Denis P [Katy, TX; Skelt, Christopher [Houston, TX
2012-02-14
A compact array of transducers is employed as a downhole instrument for acoustic investigation of the surrounding rock formation. The array is operable to generate simultaneously a first acoustic beam signal at a first frequency and a second acoustic beam signal at a second frequency different than the first frequency. These two signals can be oriented through an azimuthal rotation of the array and an inclination rotation using control of the relative phases of the signals from the transmitter elements or electromechanical linkage. Due to the non-linearity of the formation, the first and the second acoustic beam signal mix into the rock formation where they combine into a collimated third signal that propagates in the formation along the same direction than the first and second signals and has a frequency equal to the difference of the first and the second acoustic signals. The third signal is received either within the same borehole, after reflection, or another borehole, after transmission, and analyzed to determine information about rock formation. Recording of the third signal generated along several azimuthal and inclination directions also provides 3D images of the formation, information about 3D distribution of rock formation and fluid properties and an indication of the dynamic acoustic non-linearity of the formation.
Electron acoustic solitary waves in unmagnetized two electron population dense plasmas
International Nuclear Information System (INIS)
Mahmood, S.; Masood, W.
2008-01-01
The electron acoustic solitary waves are studied in unmagnetized two population electron quantum plasmas. The quantum hydrodynamic model is employed with the Sagdeev potential approach to describe the arbitrary amplitude electron acoustic waves in a two electron population dense Fermi plasma. It is found that hot electron density hump structures are formed in the subsonic region in such type of quantum plasmas. The wave amplitude as well as the width of the soliton are increased with the increase of percentage presence of cold (thinly populated) electrons in a multicomponent quantum plasma. It is found that an increase in quantum diffraction parameter broadens the nonlinear structure. Furthermore, the amplitude of the nonlinear electron acoustic wave is found to increase with the decrease in Mach number. The numerical results are also presented to understand the formation of solitons in two electron population Fermi plasmas.
International Nuclear Information System (INIS)
Kadijani, M Nouri; Abbasi, H; Pajouh, H Hakimi
2011-01-01
The effect of superthermal electrons, modeled by a Lorentzian velocity distribution function, on the oblique propagation characteristics of linear and nonlinear ion-acoustic waves in an electron-ion plasma in the presence of a uniform external magnetic field is investigated. First, the linear dispersion relations of the fast and slow modes are obtained. It is shown that the superthermal electrons make both modes propagate with smaller phase velocities. Then, the Korteweg-de Vries equation describing the propagation of nonlinear slow and fast ion-acoustic waves is derived. It is shown that the presence of superthermal electrons has a significant influence on the nature of magnetized ion-acoustic solitons. That is, for a larger population of the superthermal electrons, the soliton velocity of both modes in the laboratory frame significantly decreases and the soliton are slimmer, and on approaching the Maxwellian limit, the width becomes maximum.
2015-09-30
1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Shallow-Water Mud Acoustics William L. Siegmann...models and methods that explain observed material and acoustic properties of different physical types of shallow-ocean mud sediments. Other goals...are to assess prior data relating to the acoustic properties of mud and to provide guidance in the development and interpretation of experiments. A
Coupled Acoustic-Mechanical Bandgaps
DEFF Research Database (Denmark)
Jensen, Jakob Søndergaard; Kook, Junghwan
2016-01-01
medium and the presence of acoustic resonances. It is demonstrated that corrugation of the plate structure can introduce bending wave bandgaps and bandgaps in the acoustic domain in overlapping and audible frequency ranges. This effect is preserved also when taking the physical coupling between the two...... domains into account. Additionally, the coupling is shown to introduce extra gaps in the band structure due to modal interaction and the appearance of a cut-on frequency for the fundamental acoustic mode....
Dust ion-acoustic shock waves in magnetized pair-ion plasma with kappa distributed electrons
Kaur, B.; Singh, M.; Saini, N. S.
2018-01-01
We have performed a theoretical and numerical analysis of the three dimensional dynamics of nonlinear dust ion-acoustic shock waves (DIASWs) in a magnetized plasma, consisting of positive and negative ion fluids, kappa distributed electrons, immobile dust particulates along with positive and negative ion kinematic viscosity. By employing the reductive perturbation technique, we have derived the nonlinear Zakharov-Kuznetsov-Burgers (ZKB) equation, in which the nonlinear forces are balanced by dissipative forces (associated with kinematic viscosity). It is observed that the characteristics of DIASWs are significantly affected by superthermality of electrons, magnetic field strength, direction cosines, dust concentration, positive to negative ions mass ratio and viscosity of positive and negative ions.
Directory of Open Access Journals (Sweden)
Wei Khim Ng
2009-02-01
Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.
Ooi, Kelvin J. A.; Tan, Dawn T. H.
2017-10-01
The rapid development of graphene has opened up exciting new fields in graphene plasmonics and nonlinear optics. Graphene's unique two-dimensional band structure provides extraordinary linear and nonlinear optical properties, which have led to extreme optical confinement in graphene plasmonics and ultrahigh nonlinear optical coefficients, respectively. The synergy between graphene's linear and nonlinear optical properties gave rise to nonlinear graphene plasmonics, which greatly augments graphene-based nonlinear device performance beyond a billion-fold. This nascent field of research will eventually find far-reaching revolutionary technological applications that require device miniaturization, low power consumption and a broad range of operating wavelengths approaching the far-infrared, such as optical computing, medical instrumentation and security applications.
Acoustic Communications Measurement Systems (ACOMMS)
Federal Laboratory Consortium — FUNCTION: Design and develop adaptive signal processing techniques to improve underwater acoustic communications and networking. Phase coherent and incoherent signal...
Sinusoidal Representation of Acoustic Signals
Honda, Masaaki
Sinusoidal representation of acoustic signals has been an important tool in speech and music processing like signal analysis, synthesis and time scale or pitch modifications. It can be applicable to arbitrary signals, which is an important advantage over other signal representations like physical modeling of acoustic signals. In sinusoidal representation, acoustic signals are composed as sums of sinusoid (sine wave) with different amplitudes, frequencies and phases, which is based on the timedependent short-time Fourier transform (STFT). This article describes the principles of acoustic signal analysis/synthesis based on a sinusoid representation with focus on sine waves with rapidly varying frequency.
Guided acoustic wave inspection system
Chinn, Diane J.
2004-10-05
A system for inspecting a conduit for undesirable characteristics. A transducer system induces guided acoustic waves onto said conduit. The transducer system detects the undesirable characteristics of the conduit by receiving guided acoustic waves that contain information about the undesirable characteristics. The conduit has at least two sides and the transducer system utilizes flexural modes of propagation to provide inspection using access from only the one side of the conduit. Cracking is detected with pulse-echo testing using one transducer to both send and receive the guided acoustic waves. Thinning is detected in through-transmission testing where one transducer sends and another transducer receives the guided acoustic waves.
Tunable coupled surface acoustic cavities
de Lima, M. M.; Santos, P. V.; Kosevich, Yu. A.; Cantarero, A.
2012-06-01
We demonstrate the electric tuning of the acoustic field in acoustic microcavities (MCs) defined by a periodic arrangement of metal stripes within a surface acoustic delay line on LiNbO3 substrate. Interferometric measurements show the enhancement of the acoustic field distribution within a single MC, the presence of a "bonding" and "anti-bonding" modes for two strongly coupled MCs, as well as the positive dispersion of the "mini-bands" formed by five coupled MCs. The frequency and amplitude of the resonances can be controlled by the potential applied to the metal stripes.
Transition section for acoustic waveguides
International Nuclear Information System (INIS)
Karplus, H.H.B.
1975-01-01
A means of facilitating the transmission of acoustic waves with minimal reflection between two regions having different specific acoustic impedances is described comprising a region exhibiting a constant product of cross-sectional area and specific acoustic impedance at each cross-sectional plane along the axis of the transition region. A variety of structures that exhibit this feature is disclosed, the preferred embodiment comprising a nested structure of doubly reentrant cones. This structure is useful for monitoring the operation of nuclear reactors in which random acoustic signals are generated in the course of operation
Combined Environment Acoustic Chamber (CEAC)
Federal Laboratory Consortium — Purpose: The CEAC imposes combined acoustic, thermal and mechanical loads on aerospace structures. The CEAC is employed to measure structural response and determine...
NDE Acoustic Microscopy Research Laboratory
Federal Laboratory Consortium — The purpose is to develop advanced, more effective high-resolution micro-NDE materials characterization methods using scanning acoustic microscopy. The laboratory's...
Stationary nonlinear Airy beams
International Nuclear Information System (INIS)
Lotti, A.; Faccio, D.; Couairon, A.; Papazoglou, D. G.; Panagiotopoulos, P.; Tzortzakis, S.; Abdollahpour, D.
2011-01-01
We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.
Generalized Nonlinear Yule Models
Lansky, Petr; Polito, Federico; Sacerdote, Laura
2016-01-01
With the aim of considering models with persistent memory we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macrovolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth...
Moderately nonlinear ultrasound propagation in blood-mimicking fluid.
Kharin, Nikolay A; Vince, D Geoffrey
2004-04-01
In medical diagnostic ultrasound (US), higher than-in-water nonlinearity of body fluids and tissue usually does not produce strong nonlinearly distorted waves because of the high absorption. The relative influence of absorption and nonlinearity can be characterized by the Gol'dberg number Gamma. There are two limiting cases in nonlinear acoustics: weak waves (Gamma 1). However, at diagnostic frequencies in tissue and body fluids, the nonlinear effects and effects of absorption more likely are comparable (Gol'dberg number Gamma approximately 1). The aim of this work was to study the nonlinear propagation of a moderately nonlinear US second harmonic signal in a blood-mimicking fluid. Quasilinear solutions to the KZK equation are presented, assuming radiation from a flat and geometrically focused circular Gaussian source. The solutions are expressed in a new simplified closed form and are in very good agreement with those of previous studies measuring and modeling Gaussian beams. The solutions also show good agreement with the measurements of the beams produced by commercially available transducers, even without special Gaussian shading.
Electrostatic supersolitons and double layers at the acoustic speed
International Nuclear Information System (INIS)
Verheest, Frank; Hellberg, Manfred A.
2015-01-01
Supersolitons are characterized by subsidiary extrema on the sides of a typical bipolar electric field signature or by association with a root beyond double layers in the fully nonlinear Sagdeev pseudopotential description. It has been proven that supersolitons may exist in several plasmas having at least three constituent species, but they cannot be found in weakly nonlinear theory. Another recent aspect of pseudopotential theory is that in certain plasma models and parameter regimes solitons and/or double layers can exist at the acoustic speed, having no reductive perturbation counterparts. Importantly, they signal coexistence between solitons having positive and negative polarity, in that one solution can be realized at a time, depending on infinitesimal perturbations from the equilibrium state. Weaving the two strands together, we demonstrate here that one can even find supersolitons and double layers at the acoustic speed, as illustrated using the model of cold positive and negative ions, in the presence of nonthermal electrons following a Cairns distribution. This model has been discussed before, but the existence and properties of supersolitons at the acoustic speed were not established at the time of publication
Electrostatic supersolitons and double layers at the acoustic speed
Energy Technology Data Exchange (ETDEWEB)
Verheest, Frank, E-mail: frank.verheest@ugent.be [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B–9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Hellberg, Manfred A., E-mail: hellberg@ukzn.ac.za [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)
2015-01-15
Supersolitons are characterized by subsidiary extrema on the sides of a typical bipolar electric field signature or by association with a root beyond double layers in the fully nonlinear Sagdeev pseudopotential description. It has been proven that supersolitons may exist in several plasmas having at least three constituent species, but they cannot be found in weakly nonlinear theory. Another recent aspect of pseudopotential theory is that in certain plasma models and parameter regimes solitons and/or double layers can exist at the acoustic speed, having no reductive perturbation counterparts. Importantly, they signal coexistence between solitons having positive and negative polarity, in that one solution can be realized at a time, depending on infinitesimal perturbations from the equilibrium state. Weaving the two strands together, we demonstrate here that one can even find supersolitons and double layers at the acoustic speed, as illustrated using the model of cold positive and negative ions, in the presence of nonthermal electrons following a Cairns distribution. This model has been discussed before, but the existence and properties of supersolitons at the acoustic speed were not established at the time of publication.
Uraltseva, N N
1995-01-01
This collection focuses on nonlinear problems in partial differential equations. Most of the papers are based on lectures presented at the seminar on partial differential equations and mathematical physics at St. Petersburg University. Among the topics explored are the existence and properties of solutions of various classes of nonlinear evolution equations, nonlinear imbedding theorems, bifurcations of solutions, and equations of mathematical physics (Navier-Stokes type equations and the nonlinear Schrödinger equation). The book will be useful to researchers and graduate students working in p
Kono, Mitsuo
2010-01-01
A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.
Nonlinear optics at interfaces
International Nuclear Information System (INIS)
Chen, C.K.
1980-12-01
Two aspects of surface nonlinear optics are explored in this thesis. The first part is a theoretical and experimental study of nonlinear intraction of surface plasmons and bulk photons at metal-dielectric interfaces. The second part is a demonstration and study of surface enhanced second harmonic generation at rough metal surfaces. A general formulation for nonlinear interaction of surface plasmons at metal-dielectric interfaces is presented and applied to both second and third order nonlinear processes. Experimental results for coherent second and third harmonic generation by surface plasmons and surface coherent antiStokes Raman spectroscopy (CARS) are shown to be in good agreement with the theory
International Nuclear Information System (INIS)
Zelenyj, L.M.; Kuznetsova, M.M.
1989-01-01
Nonlinear study of magnetic perturbation development under single-mode conditions in collision-free plasma in configurations with the magnetic field shear is investigated. Results are obtained with regard of transverse component of electrical field and its effect on ion dynamics within wide range of ion Larmor radius value and values of magnetic field shear. Increments of nonlinear drift tearing mode are obtained and it is shown that excitation drastic conditions of even linearly stable modes are possible. Mechanism of instability nonlinear stabilization is considered and the value of magnetic island at the saturation threshold is estimeted. Energy of nonlinear drift tearing mode is discussed
An acoustic method for predicting relative strengths of cohesive sediment deposits
Reed, A. H.; Sanders, W. M.
2017-12-01
Cohesive sediment dynamics are fundamentally determined by sediment mineralogy, organic matter composition, ionic strength of water, and currents. These factors work to bind the cohesive sediments and to determine depositional rates. Once deposited the sediments exhibit a nonlinear response to stress and they develop increases in shear strength. Shear strength is critically important in resuspension, transport, creep, and failure predictions. Typically, shear strength is determined by point measurements, both indirectly from free-fall penetrometers or directly on cores with a shear vane. These values are then used to interpolate over larger areas. However, the remote determination of these properties would provide continuos coverage, yet it has proven difficult with sonar systems. Recently, findings from an acoustic study on cohesive sediments in a laboratory setting suggests that cohesive sediments may be differentiated using parametric acoustics; this method pulses two primary frequencies into the sediment and the resultant difference frequency is used to determine the degree of acoustic nonlinearity within the sediment. In this study, two marine clay species, kaolinite and montmorillonite, and two biopolymers, guar gum and xanthan gum were mixed to make nine different samples. The samples were evaluated in a parametric acoustic measurement tank. From the parametric acoustic measurements, the quadratic nonlinearity coefficient (beta) was determined. beta was correlated with the cation exchange capacity (CEC), an indicator of shear strength. The results indicate that increased acoustic nonlinearity correlates with increased CEC. From this work, laboratory measurements indicate that this correlation may be used evaluate geotechnical properties of cohesive sediments and may provide a means to predict sediment weakness in subaqueous environments.
Nonlinear effects on the rotor driven by a motor with limited power
Czech Academy of Sciences Publication Activity Database
Půst, Ladislav
2007-01-01
Roč. 1, č. 2 (2007), s. 603-612 ISSN 1802-680X. [Computational Mechanics 2007. Hrad Nečtiny, 05.11.2007-07.11.2007] R&D Projects: GA ČR GA101/06/0063 Institutional research plan: CEZ:AV0Z20760514 Keywords : rotor dynamics * nonlinear oscillations * weak energy source * nonlinear magnetic flux Subject RIV: BI - Acoustics
Acoustic transparency and slow sound using detuned acoustic resonators
DEFF Research Database (Denmark)
Santillan, Arturo Orozco; Bozhevolnyi, Sergey I.
2011-01-01
We demonstrate that the phenomenon of acoustic transparency and slowsound propagation can be realized with detuned acoustic resonators (DAR), mimicking thereby the effect of electromagnetically induced transparency (EIT) in atomic physics. Sound propagation in a pipe with a series of side...
Polarization Nonlinear Optics of Quadratically Nonlinear Azopolymers
International Nuclear Information System (INIS)
Konorov, S.O.; Akimov, D.A.; Ivanov, A.A.; Petrov, A.N.; Alfimov, M.V.; Yakimanskii, A.V.; Smirnov, N.N.; Ivanova, V.N.; Kudryavtsev, V.V.; Podshivalov, A.A.; Sokolova, I.M.; Zheltikov, A.M.
2005-01-01
The polarization properties of second harmonic and sum-frequency signals generated by femtosecond laser pulses in films of polymers containing covalent groups of an azobenzothiazole chromophore polarized by an external electric field are investigated. It is shown that the methods of polarization nonlinear optics make it possible to determine the structure of oriented molecular dipoles and reveal important properties of the motion of collectivized πelectrons in organic molecules with strong optical nonlinearities. The polarization measurements show that the tensor of quadratic nonlinear optical susceptibility of chromophore fragments oriented by an external field in macromolecules of the noted azopolymers has a degenerate form. This is indicative of a predominantly one-dimensional character of motion of collectivized π electrons along an extended group of atoms in such molecules
Acoustic Mechanical Feedthroughs
Sherrit, Stewart; Walkemeyer, Phillip; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea
2013-01-01
Electromagnetic motors can have problems when operating in extreme environments. In addition, if one needs to do mechanical work outside a structure, electrical feedthroughs are required to transport the electric power to drive the motor. In this paper, we present designs for driving rotary and linear motors by pumping stress waves across a structure or barrier. We accomplish this by designing a piezoelectric actuator on one side of the structure and a resonance structure that is matched to the piezoelectric resonance of the actuator on the other side. Typically, piezoelectric motors can be designed with high torques and lower speeds without the need for gears. One can also use other actuation materials such as electrostrictive, or magnetostrictive materials in a benign environment and transmit the power in acoustic form as a stress wave and actuate mechanisms that are external to the benign environment. This technology removes the need to perforate a structure and allows work to be done directly on the other side of a structure without the use of electrical feedthroughs, which can weaken the structure, pipe, or vessel. Acoustic energy is pumped as a stress wave at a set frequency or range of frequencies to produce rotary or linear motion in a structure. This method of transferring useful mechanical work across solid barriers by pumping acoustic energy through a resonant structure features the ability to transfer work (rotary or linear motion) across pressure or thermal barriers, or in a sterile environment, without generating contaminants. Reflectors in the wall of barriers can be designed to enhance the efficiency of the energy/power transmission. The method features the ability to produce a bi-directional driving mechanism using higher-mode resonances. There are a variety of applications where the presence of a motor is complicated by thermal or chemical environments that would be hostile to the motor components and reduce life and, in some instances, not be
Baryon Acoustic Oscillations reconstruction with pixels
Energy Technology Data Exchange (ETDEWEB)
Obuljen, Andrej [SISSA—International School for Advanced Studies, Via Bonomea 265, 34136 Trieste (Italy); Villaescusa-Navarro, Francisco [Center for Computational Astrophysics, 160 5th Ave, New York, NY, 10010 (United States); Castorina, Emanuele [Berkeley Center for Cosmological Physics, University of California, Berkeley, CA 94720 (United States); Viel, Matteo, E-mail: aobuljen@sissa.it, E-mail: fvillaescusa@simonsfoundation.org, E-mail: ecastorina@berkeley.edu, E-mail: viel@oats.inaf.it [INAF, Osservatorio Astronomico di Trieste, via Tiepolo 11, I-34131 Trieste (Italy)
2017-09-01
Gravitational non-linear evolution induces a shift in the position of the baryon acoustic oscillations (BAO) peak together with a damping and broadening of its shape that bias and degrades the accuracy with which the position of the peak can be determined. BAO reconstruction is a technique developed to undo part of the effect of non-linearities. We present and analyse a reconstruction method that consists of displacing pixels instead of galaxies and whose implementation is easier than the standard reconstruction method. We show that this method is equivalent to the standard reconstruction technique in the limit where the number of pixels becomes very large. This method is particularly useful in surveys where individual galaxies are not resolved, as in 21cm intensity mapping observations. We validate this method by reconstructing mock pixelated maps, that we build from the distribution of matter and halos in real- and redshift-space, from a large set of numerical simulations. We find that this method is able to decrease the uncertainty in the BAO peak position by 30-50% over the typical angular resolution scales of 21 cm intensity mapping experiments.
International Nuclear Information System (INIS)
Zhang Wan-Zhen; Chen Zhe-Bo; Xia Bin-Feng; Lin Bin; Cao Xiang-Qun
2014-01-01
Digital structured light (SL) profilometry is increasingly used in three-dimensional (3D) measurement technology. However, the nonlinearity of the off-the-shelf projectors and cameras seriously reduces the measurement accuracy. In this paper, first, we review the nonlinear effects of the projector–camera system in the phase-shifting structured light depth measurement method. We show that high order harmonic wave components lead to phase error in the phase-shifting method. Then a practical method based on frequency domain filtering is proposed for nonlinear error reduction. By using this method, the nonlinear calibration of the SL system is not required. Moreover, both the nonlinear effects of the projector and the camera can be effectively reduced. The simulations and experiments have verified our nonlinear correction method. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
International Nuclear Information System (INIS)
Matsumoto, Kunihiko; Niitsu, Mamoru; Yoshioka, Hiroshi; Tanaka, Yumiko; Anno, Izumi; Kuramoto, Kenmei; Itai, Yuji
1994-01-01
Thirty six patients were studied with a 1.5 T superconductive magnetic resonance imager. Small neurinomas appeared as homogenous intensities, large neurinomas as heterogenous intensities in T 1 and T 2 weighted images. Dural tail representing reactive change of the meninges was seen in our three acoustic neurinomas. High resolution, thin slice, MR imaging was particularly useful for intracanalicular tumor to see the relationship between the tumor and facial nerve. Total or near-total removal of tumor was performed in thirteen cases, in which functional preservation of the cochlear nerve was achieved in only three cases. (author)
International Nuclear Information System (INIS)
Kim, Yang Han
2005-09-01
This book mentions string vibration and wave, one-dimension wave and wave equation, characteristic impedance, governing equation of string, and wave energy from string, wave equation of wave and basic physical quantity like one-dimension wave equation, sound unit, sound intensity and energy, sound movement in a surface of discontinuity with transmission loss of sound by partition, and Snell's law, radiation, scatter and diffraction and sound in closed space with Sabine's theory, sound characteristic of closed space and duct acoustics.
Oscillating acoustic streaming jet
International Nuclear Information System (INIS)
Moudjed, Brahim; Botton, Valery; Henry, Daniel; Millet, Severine; Ben Hadid, Hamda; Garandet, Jean-Paul
2014-01-01
The present paper provides the first experimental investigation of an oscillating acoustic streaming jet. The observations are performed in the far field of a 2 MHz circular plane ultrasound transducer introduced in a rectangular cavity filled with water. Measurements are made by Particle Image Velocimetry (PIV) in horizontal and vertical planes near the end of the cavity. Oscillations of the jet appear in this zone, for a sufficiently high Reynolds number, as an intermittent phenomenon on an otherwise straight jet fluctuating in intensity. The observed perturbation pattern is similar to that of former theoretical studies. This intermittently oscillatory behavior is the first step to the transition to turbulence. (authors)
Acoustic classification of dwellings
DEFF Research Database (Denmark)
Berardi, Umberto; Rasmussen, Birgit
2014-01-01
insulation performance, national schemes for sound classification of dwellings have been developed in several European countries. These schemes define acoustic classes according to different levels of sound insulation. Due to the lack of coordination among countries, a significant diversity in terms...... exchanging experiences about constructions fulfilling different classes, reducing trade barriers, and finally increasing the sound insulation of dwellings.......Schemes for the classification of dwellings according to different building performances have been proposed in the last years worldwide. The general idea behind these schemes relates to the positive impact a higher label, and thus a better performance, should have. In particular, focusing on sound...
Simulation and measurement of nonlinear behavior in a high-power test cell.
Harvey, Gerald; Gachagan, Anthony
2011-04-01
High-power ultrasound has many diverse uses in process applications in industries ranging from food to pharmaceutical. Because cavitation is frequently a desirable effect within many high-power, low-frequency systems, these systems are commonly expected to feature highly nonlinear acoustic propagation because of the high input levels employed. This generation of harmonics significantly alters the field profile compared with that of a linear system, making accurate field modeling difficult. However, when the short propagation distances involved are considered, it is not unreasonable to assume that these systems may remain largely linear until the onset of cavitation, in terms of classical acoustic propagation. The purpose of this paper is to investigate the possible nonlinear effects within such systems before the onset of cavitation. A theoretical description of nonlinear propagation will be presented and the merits of common analytical models will be discussed. Following this, a numerical model of nonlinearity will be outlined and the advantages it presents for representing nonlinear effects in bounded fields will be discussed. Next, the driving equipment and transducers will be evaluated for linearity to disengage any effects from those formed in the transmission load. Finally, the linearity of the system will be measured using an acoustic hydrophone and compared with finite element analysis to confirm that nonlinear effects are not prevalent in such systems at the onset of cavitation. © 2011 IEEE
A numerical study on acoustic behavior in gas turbine combustor with acoustic resonator
International Nuclear Information System (INIS)
Park, I Sun; Sohn, Chae Hoon
2005-01-01
Acoustic behavior in gas turbine combustor with acoustic resonator is investigated numerically by adopting linear acoustic analysis. Helmholtz-type resonator is employed as acoustic resonator to suppress acoustic instability passively. The tuning frequency of acoustic resonator is adjusted by varying its length. Through harmonic analysis, acoustic-pressure responses of chamber to acoustic excitation are obtained and the resonant acoustic modes are identified. Acoustic damping effect of acoustic resonator is quantified by damping factor. As the tuning frequency of acoustic resonator approaches the target frequency of the resonant mode to be suppressed, mode split from the original resonant mode to lower and upper modes appears and thereby complex patterns of acoustic responses show up. Considering mode split and damping effect as a function of tuning frequency, it is desirable to make acoustic resonator tuned to broad-band frequencies near the maximum frequency of those of the possible upper modes
Nonlinear dynamics in Nuclotron
International Nuclear Information System (INIS)
Dinev, D.
1997-01-01
The paper represents an extensive study of the nonlinear beam dynamics in the Nuclotron. Chromatic effects, including the dependence of the betatron tunes on the amplitude, and chromatic perturbations have been investigated taking into account the measured field imperfections. Beam distortion, smear, dynamic aperture and nonlinear acceptance have been calculated for different particle energies and betatron tunes
Nonlinear Optics and Applications
Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)
2007-01-01
Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.
Acoustic Levitation With One Driver
Wang, T. G.; Rudnick, I.; Elleman, D. D.; Stoneburner, J. D.
1985-01-01
Report discusses acoustic levitation in rectangular chamber using one driver mounted at corner. Placement of driver at corner enables it to couple effectively to acoustic modes along all three axes. Use of single driver reduces cost, complexity and weight of levitation system below those of three driver system.
Acoustic Levitation With One Transducer
Barmatz, Martin B.
1987-01-01
Higher resonator modes enables simplification of equipment. Experimental acoustic levitator for high-temperature containerless processing has round cylindrical levitation chamber and only one acoustic transducer. Stable levitation of solid particle or liquid drop achieved by exciting sound in chamber to higher-order resonant mode that makes potential well for levitated particle or drop at some point within chamber.
Digital Controller For Acoustic Levitation
Tarver, D. Kent
1989-01-01
Acoustic driver digitally controls sound fields along three axes. Allows computerized acoustic levitation and manipulation of small objects for such purposes as containerless processing and nuclear-fusion power experiments. Also used for controlling motion of vibration-testing tables in three dimensions.
Acoustic engineering and technology '90
International Nuclear Information System (INIS)
1990-01-01
Acoustic monitoring, testing and diagnosis in machines, production processes and products enhance the uptimes and profitability of machinery and plants. 18 papers discuss the current state of the art of acoustic monitoring systems including integrated factory planning as well as industrial health, and noise protection. (DG) [de
Scattering Of Nonplanar Acoustic Waves
Gillman, Judith M.; Farassat, F.; Myers, M. K.
1995-01-01
Report presents theoretical study of scattering of nonplanar acoustic waves by rigid bodies. Study performed as part of effort to develop means of predicting scattering, from aircraft fuselages, of noise made by rotating blades. Basic approach was to model acoustic scattering by use of boundary integral equation to solve equation by the Galerkin method.
Acoustical Properties of Contemporary Mosques
Karaman Özgül Yılmaz; Güzel Neslihan Onat
2017-01-01
Religious buildings are important for many communities because of their representation of different beliefs. In such structures, the sense of individuality or unity & togetherness are created according to variable worship activities; these different uses have also different acoustical requirements. In order to create the desired feeling in the space at the required time, rooms should be evaluated in terms of acoustical conditions.
Acoustic Center or Time Origin?
DEFF Research Database (Denmark)
Staffeldt, Henrik
1999-01-01
The paper discusses the acoustic center in relation to measurements of loudspeaker polar data. Also, it presents the related concept time origin and discusses the deviation that appears between positions of the acoustic center found by wavefront based and time based measuring methods....
Propagation of Ion Acoustic Perturbations
DEFF Research Database (Denmark)
Pécseli, Hans
1975-01-01
Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered.......Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered....
Acoustic Emission Technology and Application
International Nuclear Information System (INIS)
Joo, Y. S.; Lim, S. H.; Eom, H. S.; Kim, J. H.; Jung, H. K.
2003-10-01
Acoustic emission is the elastic wave that is generated by the rapid release of energy from the localized sources within a material. After the observation of acoustic emission phenomenon in 1950, the research and further investigation had been performed. Acoustic emission examination becomes a rapidly matured nondestructive testing method with demonstrated capabilities for characterizing material behavior and for detecting the defect. It is of interest as a possible passive monitoring technique for detecting, locating and characterizing the defects in component and structure. Acoustic emission technology has recently strengthened the on-line monitoring application for the detection of incipient failures and the assurance of structural integrity. The field of acoustic emission testing is still growing vigorously and presents many challenges. Especially, acoustic emission has been successfully applied in the leak detection of primary pressure boundary of nuclear power plants. In this state-of-art report, the principle, measurement and field applications of acoustic emission technique is reviewed and summarized. Acoustic emission technology will contribute to the assurance of nuclear safety as the on-line monitoring technique of structural integrity of NSSS components and structures
Dynamics of beam-driven Langmuir and ion-acoustic waves including electrostatic decay
International Nuclear Information System (INIS)
Li, B.; Willes, A.J.; Robinson, P.A.; Cairns, I.H.
2003-01-01
The evolution of Langmuir waves and ion-acoustic waves stimulated by a hot electron beam in an initially homogeneous plasma is investigated numerically in time, position, and wave number space. Quasilinear interactions between the beam particles and Langmuir waves, nonlinear interactions between the Langmuir and ion-acoustic waves through Langmuir decay processes, and spontaneous emission are taken into account in the kinetic theory employed. For illustrative parameters of those in the solar wind near 1 a.u., nonlinear Langmuir decays are observed to transfer the beam-driven Langmuir waves rapidly out of resonance. The scattered Langmuir waves then undergo further decays, moving sequentially toward small wave numbers, until decay is kinematically prohibited. The main features of the evolution of Langmuir and ion-acoustic waves are spatially inhomogeneous. The scattered Langmuir spectra increase and eventually reach or exceed the beam-driven Langmuir spectra at a given spatial location (except in regions where further decays proceed). The ion-acoustic waves are relatively weak and subject to damping at the later stages of their evolution. The development of fine structures in the product Langmuir and ion-acoustic waves are observed, due to depletion of their energy by decay and dominant damping effects, respectively. The propagation of the beam is essentially unaffected by the operation of the decay process. The decay process is thus slaved to the primary beam-plasma evolution, as assumed in previous studies. A variation of the ratio of electron temperature to ion temperature is found to affect not only the ion-acoustic wave levels through effects on the damping rate, but also the dynamics of decay via effects on the decay rate. The latter was not addressed in previous studies. Furthermore, spontaneous emission of ion-acoustic waves is found to affect the dynamics of decay, thus its inclusion is necessary to correctly model the Langmuir and ion-acoustic spectra
Lugiato, Luigi; Brambilla, Massimo
2015-01-01
Guiding graduate students and researchers through the complex world of laser physics and nonlinear optics, this book provides an in-depth exploration of the dynamics of lasers and other relevant optical systems, under the umbrella of a unitary spatio-temporal vision. Adopting a balanced approach, the book covers traditional as well as special topics in laser physics, quantum electronics and nonlinear optics, treating them from the viewpoint of nonlinear dynamical systems. These include laser emission, frequency generation, solitons, optically bistable systems, pulsations and chaos and optical pattern formation. It also provides a coherent and up-to-date treatment of the hierarchy of nonlinear optical models and of the rich variety of phenomena they describe, helping readers to understand the limits of validity of each model and the connections among the phenomena. It is ideal for graduate students and researchers in nonlinear optics, quantum electronics, laser physics and photonics.
Electron/electron acoustic instability
International Nuclear Information System (INIS)
Gary, S.P.
1987-01-01
The electron acoustic wave becomes a normal mode of an unmagnetized collisionless plasma in the presence of two electron components with similar densities, but strongly disparate temperatures. The characteristic frequency of this mode is the plasma frequency of the cooler electron component. If these two electron components have a relative drift speed several times the thermal speed of the cooler component, the electron/electron acoustic instability may arise. This paper describes the parametric dependences of the threshold drift speed and maximum growth rate of this instability, and compares these with the same properties of the electron/ion acoustic instability. Under the condition of zero current, the electron/ion acoustic instability typically has the lower threshold drift speed, so that observation of the electron/electron acoustic instability is a strong indication of the presence of an electrical current in the plasma
Acoustic emission linear pulse holography
Collins, H.D.; Busse, L.J.; Lemon, D.K.
1983-10-25
This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.
International Nuclear Information System (INIS)
Nejoh, Y.N.
1997-01-01
The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with positrons. We have presented the region of existence of the ion-acoustic waves by analysing the structure of the pseudopotential. The region of existence sensitively depends on the positron to electron density ratio, the ion to electron mass ratio and the positron to electron temperature ratio. It is shown that the maximum Mach number increases as the positron temperature increases and the region of existence of the ion-acoustic waves spreads as the positron temperature increases. 12 refs., 6 figs
Damaske, Peter
2008-01-01
When one listens to music at home, one would like to have an acoustic impression close to that of being in the concert hall. Until recently this meant elaborate multi-channelled sound systems with 5 or more speakers. But head-related stereophony achieves the surround-sound effect in living rooms with only two loudspeakers. By virtue of their slight directivity as well as an electronic filter the limitations previously common to two-speaker systems can be overcome and this holds for any arbitrary two-channel recording. The book also investigates the question of how a wide and diffuse sound image can arise in concert halls and shows that the quality of concert halls decisively depends on diffuse sound images arising in the onset of reverberation. For this purpose a strong onset of reverberation is modified in an anechoic chamber by electroacoustic means. Acoustics and Hearing proposes ideas concerning signal processing in the auditory system that explain the measured results and the resultant sound effects plea...
Omnidirectional ventilated acoustic barrier
Zhang, Hai-long; Zhu, Yi-fan; Liang, Bin; Yang, Jing; Yang, Jun; Cheng, Jian-chun
2017-11-01
As an important problem in acoustics, sound insulation finds applications in a great variety of situations. In the existing schemes, however, there has always been a trade-off between the thinness of sound-insulating devices and their ventilating capabilities, limiting their potentials in the control of low-frequency sound in high ventilation environments. Here, we design and experimentally implement an omnidirectional acoustic barrier with a planar profile, subwavelength thickness ( 0.18 λ ), yet high ventilation. The proposed mechanism is based on the interference between the resonant scattering of discrete states and the background scattering of continuous states which induces a Fano-like asymmetric transmission profile. Benefitting from the binary-structured design of the coiled unit and hollow pipe, it maximally simplifies the design and fabrication while ensuring the ventilation for all the non-resonant units with open tubes. The simulated and measured results agree well, showing the effectiveness of our proposed mechanism to block low frequency sound coming from various directions while allowing 63% of the air flow to pass. We anticipate our design to open routes to design sound insulators and to enable applications in traditionally unattainable cases such as those calling for noise reduction and cooling simultaneously.
[Acoustical parameters of toys].
Harazin, Barbara
2010-01-01
Toys play an important role in the development of the sight and hearing concentration in children. They also support the development of manipulation, gently influence a child and excite its emotional activities. A lot of toys emit various sounds. The aim of the study was to assess sound levels produced by sound-emitting toys used by young children. Acoustical parameters of noise were evaluated for 16 sound-emitting plastic toys in laboratory conditions. The noise level was recorded at four different distances, 10, 20, 25 and 30 cm, from the toy. Measurements of A-weighted sound pressure levels and noise levels in octave band in the frequency range from 31.5 Hz to 16 kHz were performed at each distance. Taking into consideration the highest equivalent A-weighted sound levels produced by tested toys, they can be divided into four groups: below 70 dB (6 toys), from 70 to 74 dB (4 toys), from 75 to 84 dB (3 toys) and from 85 to 94 dB (3 toys). The majority of toys (81%) emitted dominant sound levels in octave band at the frequency range from 2 kHz to 4 kHz. Sound-emitting toys produce the highest acoustic energy at the frequency range of the highest susceptibility of the auditory system. Noise levels produced by some toys can be dangerous to children's hearing.
Directory of Open Access Journals (Sweden)
Y. G. Rapoport
2017-01-01
Full Text Available We develop theoretical basics of active experiments with two beams of acoustic waves, radiated by a ground-based sound generator. These beams are transformed into atmospheric acoustic gravity waves (AGWs, which have parameters that enable them to penetrate to the altitudes of the ionospheric E and F regions where they influence the electron concentration of the ionosphere. Acoustic waves are generated by the ground-based parametric sound generator (PSG at the two close frequencies. The main idea of the experiment is to design the output parameters of the PSG to build a cascade scheme of nonlinear wave frequency downshift transformations to provide the necessary conditions for their vertical propagation and to enable penetration to ionospheric altitudes. The PSG generates sound waves (SWs with frequencies f1 = 600 and f2 = 625 Hz and large amplitudes (100–420 m s−1. Each of these waves is modulated with the frequency of 0.016 Hz. The novelty of the proposed analytical–numerical model is due to simultaneous accounting for nonlinearity, diffraction, losses, and dispersion and inclusion of the two-stage transformation (1 of the initial acoustic waves to the acoustic wave with the difference frequency Δf = f2 − f1 in the altitude ranges 0–0.1 km, in the strongly nonlinear regime, and (2 of the acoustic wave with the difference frequency to atmospheric acoustic gravity waves with the modulational frequency in the altitude ranges 0.1–20 km, which then reach the altitudes of the ionospheric E and F regions, in a practically linear regime. AGWs, nonlinearly transformed from the sound waves, launched by the two-frequency ground-based sound generator can increase the transparency of the ionosphere for the electromagnetic waves in HF (MHz and VLF (kHz ranges. The developed theoretical model can be used for interpreting an active experiment that includes the PSG impact on the atmosphere–ionosphere system
Review of Progress in Acoustic Levitation
Andrade, Marco A. B.; Pérez, Nicolás; Adamowski, Julio C.
2018-04-01
Acoustic levitation uses acoustic radiation forces to counteract gravity and suspend objects in mid-air. Although acoustic levitation was first demonstrated almost a century ago, for a long time, it was limited to objects much smaller than the acoustic wavelength levitating at fixed positions in space. Recent advances in acoustic levitation now allow not only suspending but also rotating and translating objects in three dimensions. Acoustic levitation is also no longer restricted to small objects and can now be employed to levitate objects larger than the acoustic wavelength. This article reviews the progress of acoustic levitation, focusing on the working mechanism of different types of acoustic levitation devices developed to date. We start with a brief review of the theory. Then, we review the acoustic levitation methods to suspend objects at fixed positions, followed by the techniques that allow the manipulation of objects. Finally, we present a brief summary and offer some future perspectives for acoustic levitation.
Ficuciello, A.; Blaisot, J. B.; Richard, C.; Baillot, F.
2017-06-01
An experimental investigation of the effects of a high amplitude transverse acoustic field on coaxial jets is presented in this paper. Water and air are used as working fluids at ambient pressure. The coaxial injectors are placed on the top of a semi-open resonant cavity where the acoustic pressure fluctuations of the standing wave can reach a maximum peak-to-peak amplitude of 12 kPa at the forcing frequency of 1 kHz. Several test conditions are considered in order to quantify the influence of injection conditions, acoustic field amplitude, and injector position with respect to the standing wave acoustic field. A high speed back-light visualization technique is used to characterize the jet response. Image processing is used to obtain valuable information about the jet behavior. It is shown that the acoustic field drastically affects the atomization process for all atomization regimes. The position of the injector in the acoustic field determines the jet response, and a droplet-clustering phenomenon is highlighted in multi-point injection conditions and quantified by determining discrete droplet location distributions. A theoretical model based on nonlinear acoustics related to the spatial distribution of the radiation pressure exerted on an object explains the behavior observed.
Thermal-Acoustic Fatigue of a Multilayer Thermal Protection System in Combined Extreme Environments
Directory of Open Access Journals (Sweden)
Liu Liu
2014-06-01
Full Text Available In order to ensure integrity of thermal protection system (TPS structure for hypersonic vehicles exposed to severe operating environments, a study is undertaken to investigate the response and thermal-acoustic fatigue damage of a representative multilayer TPS structure under combined thermal and acoustic loads. An unsteady-state flight of a hypersonic vehicle is composed of a series of steady-state snapshots, and for each snapshot an acoustic load is imposed to a static steady-state TPS structure. A multistep thermal-acoustic fatigue damage intensity analysis procedure is given and consists of a heat transfer analysis, a nonlinear thermoelastic analysis, and a random response analysis under a combined loading environment and the fatigue damage intensity has been evaluated with two fatigue analysis techniques. The effects of thermally induced deterministic stress and nondeterministic dynamic stress due to the acoustic loading have been considered in the damage intensity estimation with a maximum stress fatigue model. The results show that the given thermal-acoustic fatigue intensity estimation procedure is a viable approach for life prediction of TPS structures under a typical mission cycle with combined loadings characterized by largely different time-scales. A discussion of the effects of the thermal load, the acoustic load, and fatigue analysis methodology on the fatigue damage intensity has been provided.
International Nuclear Information System (INIS)
Han, Jiu-Ning; Luo, Jun-Hua; Sun, Gui-Hua; Liu, Zhen-Lai; Ge, Su-Hong; Wang, Xin-Xing; Li, Jun-Xiu
2014-01-01
The nonlinear dynamics of nonplanar (cylindrical and spherical) electron-acoustic solitary wave structures in an unmagnetized, collisionless plasma composed of stationary ions, cold fluid electrons and hot q-nonextensive distributed electrons are theoretically studied. We discuss the effects of the nonplanar geometry, nonextensivity of hot electrons and ‘hot’ to ‘cold’ electron number density ratio on the time evolution characters of cylindrical and spherical solitary waves. Moreover, the effects of plasma parameters on the nonlinear structure induced by the interaction between two planar solitary waves are also investigated. It is found that these plasma parameters have significant influences on the properties of the above-mentioned nonlinear structures. Our theoretical study may be useful to understand the nonlinear features of electron-acoustic wave structures in astrophysical plasma systems. (paper)
Nonlinear partial differential equations for scientists and engineers
Debnath, Lokenath
1997-01-01
"An exceptionally complete overview. There are numerous examples and the emphasis is on applications to almost all areas of science and engineering. There is truly something for everyone here. This reviewer feels that it is a very hard act to follow, and recommends it strongly. [This book] is a jewel." ---Applied Mechanics Review (Review of First Edition) This expanded and revised second edition is a comprehensive and systematic treatment of linear and nonlinear partial differential equations and their varied applications. Building upon the successful material of the first book, this edition contains updated modern examples and applications from areas of fluid dynamics, gas dynamics, plasma physics, nonlinear dynamics, quantum mechanics, nonlinear optics, acoustics, and wave propagation. Methods and properties of solutions are presented, along with their physical significance, making the book more useful for a diverse readership. Topics and key features: * Thorough coverage of derivation and methods of soluti...
A Simple Model for Nonlinear Confocal Ultrasonic Beams
Zhang, Dong; Zhou, Lin; Si, Li-Sheng; Gong, Xiu-Fen
2007-01-01
A confocally and coaxially arranged pair of focused transmitter and receiver represents one of the best geometries for medical ultrasonic imaging and non-invasive detection. We develop a simple theoretical model for describing the nonlinear propagation of a confocal ultrasonic beam in biological tissues. On the basis of the parabolic approximation and quasi-linear approximation, the nonlinear Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation is solved by using the angular spectrum approach. Gaussian superposition technique is applied to simplify the solution, and an analytical solution for the second harmonics in the confocal ultrasonic beam is presented. Measurements are performed to examine the validity of the theoretical model. This model provides a preliminary model for acoustic nonlinear microscopy.
Nonlinear photonic metasurfaces
Li, Guixin; Zhang, Shuang; Zentgraf, Thomas
2017-03-01
Compared with conventional optical elements, 2D photonic metasurfaces, consisting of arrays of antennas with subwavelength thickness (the 'meta-atoms'), enable the manipulation of light-matter interactions on more compact platforms. The use of metasurfaces with spatially varying arrangements of meta-atoms that have subwavelength lateral resolution allows control of the polarization, phase and amplitude of light. Many exotic phenomena have been successfully demonstrated in linear optics; however, to meet the growing demand for the integration of more functionalities into a single optoelectronic circuit, the tailorable nonlinear optical properties of metasurfaces will also need to be exploited. In this Review, we discuss the design of nonlinear photonic metasurfaces — in particular, the criteria for choosing the materials and symmetries of the meta-atoms — for the realization of nonlinear optical chirality, nonlinear geometric Berry phase and nonlinear wavefront engineering. Finally, we survey the application of nonlinear photonic metasurfaces in optical switching and modulation, and we conclude with an outlook on their use for terahertz nonlinear optics and quantum information processing.