WorldWideScience

Sample records for acoustic waves

  1. 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...

  2. Strong acoustic wave action

    Gokhberg, M. B.

    1983-07-01

    Experiments devoted to acoustic action on the atmosphere-magnetosphere-ionosphere system using ground based strong explosions are reviewed. The propagation of acoustic waves was observed by ground observations over 2000 km in horizontal direction and to an altitude of 200 km. Magnetic variations up to 100 nT were detected by ARIEL-3 satellite near the epicenter of the explosion connected with the formation of strong field aligned currents in the magnetosphere. The enhancement of VLF emission at 800 km altitude is observed.

  3. Surface Acoustic Wave Devices

    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...... application is modulation of optical waves in waveguides. This presentation elaborates on how a SAW is generated by interdigital transducers using a 2D model of a piezoelectric, inhomogeneous material implemented in the high-level programming language Comsol Multiphysics. The SAW is send through a model of a...... output waveguide and the MZI can thus be used as an optical switch. It is explained how the mechanical model of the SAW is coupled to a model of the optical waves such that the change in effective refractive index introduced in the MZI arms by the SAW can be calculated. Results of a parameter study of...

  4. On the Synchronization of Acoustic Gravity Waves

    Lonngren, Karl E.; Bai, Er-Wei

    Using the model proposed by Stenflo, we demonstrate that acoustic gravity waves found in one region of space can be synchronized with acoustic gravity waves found in another region of space using techniques from modern control theory.

  5. Nonlinear acoustic-gravity waves

    Stenflo, Lennart; Shukla, P. K.

    2009-01-01

    Previous results on nonlinear acoustic-gravity waves are reconsidered. It turns out that the mathematical techniques used are somewhat similar to those already adopted by the plasma physics community. Consequently, a future interaction between physicists On different fields, e.g in meteorology and plasma physics, can be very fruitful.

  6. Propagation behavior of acoustic wave in wood

    Huadong Xu; Guoqi Xu; Lihai Wang; Lei Yu

    2014-01-01

    We used acoustic tests on a quarter-sawn poplar timbers to study the effects of wood anisotropy and cavity defects on acoustic wave velocity and travel path, and we investigated acoustic wave propagation behavior in wood. The timber specimens were first tested in unmodified condition and then tested after introduction of cavity defects of varying sizes to quantify the transmitting time of acoustic waves in laboratory conditions. Two-dimensional acoustic wave contour maps on the radial section of specimens were then simulated and analyzed based on the experimental data. We tested the relationship between wood grain and acoustic wave velocity as waves passed in various directions through wood. Wood anisotropy has significant effects on both velocity and travel path of acoustic waves, and the velocity of waves passing longitudinally through timbers exceeded the radial velocity. Moreover, cavity defects altered acoustic wave time contours on radial sections of timbers. Acous-tic wave transits from an excitation point to the region behind a cavity in defective wood more slowly than in intact wood.

  7. Ion Acoustic Waves in the Presence of Electron Plasma Waves

    Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

    1977-01-01

    Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave.......Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave....

  8. On Collisionless Damping of Ion Acoustic Waves

    Jensen, Vagn Orla; Petersen, P.I.

    1973-01-01

    Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero.......Exact theoretical treatments show that the damping of ion acoustic waves in collisionless plasmas does not vanish when the derivative of the undisturbed distribution function at the phase velocity equals zero....

  9. Second-order dust acoustic wave theory

    A second-order perturbation theory for non-dispersive, undamped dust acoustic waves is presented. The analysis leads to a second-order wave equation with source terms consisting of (nonlinear) products of first-order terms. The nonlinear effects included in this analysis might be useful in explaining the non-sinusoidal waveforms that are observed with large-amplitude, self-excited dust acoustic waves.

  10. Unidirectional propagation of designer surface acoustic waves

    Lu, Jiuyang; Ke, Manzhu; Liu, Zhengyou

    2014-01-01

    We propose an efficient design route to generate unidirectional propagation of the designer surface acoustic waves. The whole system consists of a periodically corrugated rigid plate combining with a pair of asymmetric narrow slits. The directionality of the structure-induced surface waves stems from the destructive interference between the evanescent waves emitted from the double slits. The theoretical prediction is validated well by simulations and experiments. Promising applications can be anticipated, such as in designing compact acoustic circuits.

  11. A New Wave of Acoustics.

    Beyer, Robert

    1981-01-01

    Surveys 50 years of acoustical studies by discussing selected topics including the ear, nonlinear representations, underwater sound, acoustical diagnostics, absorption, electrolytes, phonons, magnetic interaction, and superfluidity and the five sounds. (JN)

  12. Nonlinear interaction between acoustic gravity waves

    P. Axelsson; J. Larsson; Stenflo, L.

    1996-01-01

    The resonant interaction between three acoustic gravity waves is considered. We improve on the results of previous authors and write the new coupling coefficients in a symmetric form. Particular attention is paid to the low-frequency limit.

  13. Focusing of Acoustic Waves through Acoustic Materials with Subwavelength Structures

    Xiao, Bingmu

    2013-05-01

    In this thesis, wave propagation through acoustic materials with subwavelength slits structures is studied. Guided by the findings, acoustic wave focusing is achieved with a specific material design. By using a parameter retrieving method, an effective medium theory for a slab with periodic subwavelength cut-through slits is successfully derived. The theory is based on eigenfunction solutions to the acoustic wave equation. Numerical simulations are implemented by the finite-difference time-domain (FDTD) method for the two-dimensional acoustic wave equation. The theory provides the effective impedance and refractive index functions for the equivalent medium, which can reproduce the transmission and reflection spectral responses of the original structure. I analytically and numerically investigate both the validity and limitations of the theory, and the influences of material and geometry on the effective spectral responses are studied. Results show that large contrasts in impedance and density are conditions that validate the effective medium theory, and this approximation displays a better accuracy for a thick slab with narrow slits in it. Based on the effective medium theory developed, a design of a at slab with a snake shaped" subwavelength structure is proposed as a means of achieving acoustic focusing. The property of focusing is demonstrated by FDTD simulations. Good agreement is observed between the proposed structure and the equivalent lens pre- dicted by the theory, which leads to robust broadband focusing by a thin at slab.

  14. Exciton transport by surface acoustic waves

    Rudolph, J.; Hey, R.; Santos, P. V.

    2007-05-01

    Long-range acoustic transport of excitons in GaAs quantum wells (QWs) is demonstrated. The mobile strain field of a surface acoustic wave creates a dynamic lateral type I modulation of the conduction and valence bands in a double-quantum-well (DQW) structure. This mobile potential modulation transports long-living indirect excitons in the DQW over several hundreds of μm.

  15. Imaging of Acoustic Waves in Sand

    Deason, Vance Albert; Telschow, Kenneth Louis; Watson, Scott Marshall

    2003-08-01

    There is considerable interest in detecting objects such as landmines shallowly buried in loose earth or sand. Various techniques involving microwave, acoustic, thermal and magnetic sensors have been used to detect such objects. Acoustic and microwave sensors have shown promise, especially if used together. In most cases, the sensor package is scanned over an area to eventually build up an image or map of anomalies. We are proposing an alternate, acoustic method that directly provides an image of acoustic waves in sand or soil, and their interaction with buried objects. The INEEL Laser Ultrasonic Camera utilizes dynamic holography within photorefractive recording materials. This permits one to image and demodulate acoustic waves on surfaces in real time, without scanning. A video image is produced where intensity is directly and linearly proportional to surface motion. Both specular and diffusely reflecting surfaces can be accomodated and surface motion as small as 0.1 nm can be quantitatively detected. This system was used to directly image acoustic surface waves in sand as well as in solid objects. Waves as frequencies of 16 kHz were generated using modified acoustic speakers. These waves were directed through sand toward partially buried objects. The sand container was not on a vibration isolation table, but sat on the lab floor. Interaction of wavefronts with buried objects showed reflection, diffraction and interference effects that could provide clues to location and characteristics of buried objects. Although results are preliminary, success in this effort suggests that this method could be applied to detection of buried landmines or other near-surface items such as pipes and tanks.

  16. Topological charge pump by surface acoustic waves

    Yi, Zheng; Shi-Ping, Feng; Shi-Jie, Yang

    2016-06-01

    Quantized electron pumping by the surface acoustic wave across barriers created by a sequence of split metal gates is interpreted from the viewpoint of topology. The surface acoustic wave serves as a one-dimensional periodical potential whose energy spectrum possesses the Bloch band structure. The time-dependent phase plays the role of an adiabatic parameter of the Hamiltonian which induces a geometrical phase. The pumping currents are related to the Chern numbers of the filled bands below the Fermi energy. Based on this understanding, we predict a novel effect of quantized but non-monotonous current plateaus simultaneously pumped by two homodromous surface acoustic waves. Project supported by the National Natural Science Foundation of China (Grant No. 11374036) and the National Basic Research Program of China (Grant No. 2012CB821403).

  17. Research in acoustic and optical wave technology

    Siegman, A. E.; Auld, B. A.; Kino, G. S.; Beasley, M. R.; Byer, R. L.

    1982-04-01

    This report summaries the research progress and activity 1 April 1981 through 31 March 1982. Specific Projects are: (81-1) Interaction of Acoustic and Optical Waves with Domains in Ferroic Fibers with Bulk Materials: (B.A. Auld); (81-2) High T Josephson Junctions & Circuits (M. R. Beasley); (81-3) Optical & Nonlinear Optical Studies of Single Crystal Fibers (R. L. Byer); (81-4) Acoustic Surface Wave Scanning of Optical Images, (G. S. Kino); (81-5) Picosecond Raman Studies of Electronic Solids (A. E. Siegman).

  18. Wave Phenomena in an Acoustic Resonant Chamber

    Smith, Mary E.; And Others

    1974-01-01

    Discusses the design and operation of a high Q acoustical resonant chamber which can be used to demonstrate wave phenomena such as three-dimensional normal modes, Q values, densities of states, changes in the speed of sound, Fourier decomposition, damped harmonic oscillations, sound-absorbing properties, and perturbation and scattering problems.…

  19. Marble Ageing Characterization by Acoustic Waves

    Boudani, Mohamed El; Wilkie-Chancellier, Nicolas; Martinez, Loïc; Hébert, Ronan; Rolland, Olivier; Forst, Sébastien; Vergès-Belmin, Véronique; Serfaty, Stéphane

    In cultural heritage, statue marble characterization by acoustic waves is a well-known non-destructive method. Such investigations through the statues by time of flight method (TOF) point out sound speeds decrease with ageing. However for outdoor stored statues as the ones in the gardens of Chateau de Versailles, ageing affects mainly the surface of the Carrara marble. The present paper proposes an experimental study of the marble acoustic properties variations during accelerated laboratory ageing. The surface degradation of the marble is reproduced in laboratory for 29 mm thick marble samples by using heating/cooling thermal cycles on one face of a marble plate. Acoustic waves are generated by 1 MHz central frequency contact transducers excited by a voltage pulse placed on both sides of the plate. During the ageing and by using ad hoc transducers, the marble samples are characterized in transmission, along their volume by shear, compressional TOF measurements and along their surface by Rayleigh waves measurements. For Rayleigh waves, both TOF by transducers and laser vibrometry methods are used to detect the Rayleigh wave. The transmission measurements point out a deep decrease of the waves speeds in conjunction with a dramatic decrease of the maximum frequency transmitted. The marble acts as a low pass filter whose characteristic frequency cut decreases with ageing. This pattern occurs also for the Rayleigh wave surface measurements. The speed change in conjunction with the bandwidth translation is shown to be correlated to the material de-structuration during ageing. With a similar behavior but reversed in time, the same king of phenomena have been observed trough sol-gel materials during their structuration from liquid to solid state (Martinez, L. et all (2004). "Chirp-Z analysis for sol-gel transition monitoring". Ultrasonics, 42(1), 507-510.). A model is proposed to interpret the acoustical measurements

  20. Acoustic wave-equation-based earthquake location

    Tong, Ping; Yang, Dinghui; Liu, Qinya; Yang, Xu; Harris, Jerry

    2016-04-01

    We present a novel earthquake location method using acoustic wave-equation-based traveltime inversion. The linear relationship between the location perturbation (δt0, δxs) and the resulting traveltime residual δt of a particular seismic phase, represented by the traveltime sensitivity kernel K(t0, xs) with respect to the earthquake location (t0, xs), is theoretically derived based on the adjoint method. Traveltime sensitivity kernel K(t0, xs) is formulated as a convolution between the forward and adjoint wavefields, which are calculated by numerically solving two acoustic wave equations. The advantage of this newly derived traveltime kernel is that it not only takes into account the earthquake-receiver geometry but also accurately honours the complexity of the velocity model. The earthquake location is obtained by solving a regularized least-squares problem. In 3-D realistic applications, it is computationally expensive to conduct full wave simulations. Therefore, we propose a 2.5-D approach which assumes the forward and adjoint wave simulations within a 2-D vertical plane passing through the earthquake and receiver. Various synthetic examples show the accuracy of this acoustic wave-equation-based earthquake location method. The accuracy and efficiency of the 2.5-D approach for 3-D earthquake location are further verified by its application to the 2004 Big Bear earthquake in Southern California.

  1. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Polzikova, N. I.; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P.

    2016-05-01

    We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW) resonator (HBAR) formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE) this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  2. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    N. I. Polzikova

    2016-05-01

    Full Text Available We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW resonator (HBAR formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  3. Bi-dust acoustic waves

    Martin, P.; Castro, E.; Puerta, J. [Universidad Simon Bolivar, Apartado 89000, Caracas 1080A (Venezuela); Valdeblanquez, E. [Universidad del Zulia, facultad de Ingenieria, Apartado 4011-A 526, Maracaibo, Edo. Zulia (Venezuela)

    2006-07-01

    Low frequencies waves in plasmas with two kind of dusty grains have been studied. Each species of dust particle is characterized by the grain radius, which determines its equilibrium charge. Relative velocities between the two kinds of dust grain for the unperturbed plasma is also considered in order to study instabilities and compare with astrophysical and industrial applications. In this analysis, each dust species is handled with a simplified model of kinetic-fluid equations, and the electrons and ions are determined by Boltzmann factors. The low frequency dispersion relation for bi-dust plasma waves with non relative motion between each kind of grain leads to damped waves with two characteristic frequencies. Instabilities are produced by the relative motion between the species. The onset of these instabilities is studied as a function of the plasma dust frequencies and relative velocities among each species. (Author)

  4. Acoustic-gravity waves, theory and application

    Kadri, Usama; Farrell, William E.; Munk, Walter

    2015-04-01

    Acoustic-gravity waves (AGW) propagate in the ocean under the influence of both the compressibility of sea water and the restoring force of gravity. The gravity dependence vanishes if the wave vector is normal to the ocean surface, but becomes increasingly important as the wave vector acquires a horizontal tilt. They are excited by many sources, including non-linear surface wave interactions, disturbances of the ocean bottom (submarine earthquakes and landslides) and underwater explosions. In this introductory lecture on acoustic-gravity waves, we describe their properties, and their relation to organ pipe modes, to microseisms, and to deep ocean signatures by short surface waves. We discuss the generation of AGW by underwater earthquakes; knowledge of their behaviour with water depth can be applied for the early detection of tsunamis. We also discuss their generation by the non-linear interaction of surface gravity waves, which explains the major role they play in transforming energy from the ocean surface to the crust, as part of the microseisms phenomenon. Finally, they contribute to horizontal water transport at depth, which might affect benthic life.

  5. Acoustic Remote Sensing of Rogue Waves

    Parsons, Wade; Kadri, Usama

    2016-04-01

    We propose an early warning system for approaching rogue waves using the remote sensing of acoustic-gravity waves (AGWs) - progressive sound waves that propagate at the speed of sound in the ocean. It is believed that AGWs are generated during the formation of rogue waves, carrying information on the rogue waves at near the speed of sound, i.e. much faster than the rogue wave. The capability of identifying those special sound waves would enable detecting rogue waves most efficiently. A lot of promising work has been reported on AGWs in the last few years, part of which in the context of remote sensing as an early detection of tsunami. However, to our knowledge none of the work addresses the problem of rogue waves directly. Although there remains some uncertainty as to the proper definition of a rogue wave, there is little doubt that they exist and no one can dispute the potential destructive power of rogue waves. An early warning system for such extreme waves would become a demanding safety technology. A closed form expression was developed for the pressure induced by an impulsive source at the free surface (the Green's function) from which the solution for more general sources can be developed. In particular, we used the model of the Draupner Wave of January 1st, 1995 as a source and calculated the induced AGW signature. In particular we studied the AGW signature associated with a special feature of this wave, and characteristic of rogue waves, of the absence of any local set-down beneath the main crest and the presence of a large local set-up.

  6. Holographic imaging of surface acoustic waves

    Bruno, Francois; Royer, Daniel; Atlan, Michael

    2014-01-01

    We report on an experimental demonstration of surface acoustic waves monitoring on a thin metal plate with heterodyne optical holography. Narrowband imaging of local optical pathlength modulation is achieved with a frequency-tunable time-averaged laser Doppler holographic imaging scheme on a sensor array, at video-rate. This method enables robust and quantitative mapping of out-of-plane vibrations of nanometric amplitudes at radiofrequencies.

  7. Support minimized inversion of acoustic and elastic wave scattering

    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

  8. Isomorphic surface acoustic waves on multilayer structures

    Hunt, William D.

    2001-03-01

    There has been growing interest in recent years over the investigation of bulk acoustic waves (BAWs) which propagate along certain directions in anisotropic crystals with a minimum of diffraction. One application of these BAWs is for multichannel acousto-optic devices. The fact that the beams propagate with the minimum diffraction implies that the channels in such a device can be closely packed. Since surface acoustic waves (SAWs) are constrained to be within roughly one acoustic wavelength from the surface, the possibility exists to deposit thin films of isotropic or anisotropic material on the substrate and embue the aggregate multilayer structure with properties not present in the beginning substrate material. The characteristic investigated in this article is the velocity anisotropy which, as is known, predominates SAW diffraction. Specifically, we present a method whereby self-collimating SAWs can be generated on surfaces even though the substrate material itself does not exhibit this behavior. We discuss the particular case of a ZnO layer on (001)-cut -propagating GaAs for which a fair amount of slowness surface data exists. Finally, using angular spectrum of plane waves diffraction theory, we present data which substantiate the claim that self-collimating can more accurately be viewed as isomorphic because the SAW beam profile can propagate without changing its shape.

  9. Reverse Doppler effect in backward spin waves scattered on acoustic waves

    A. V. Chumak; Dhagat, P.; Jander, A.; Serga, A. A.; Hillebrands, B

    2009-01-01

    We report on the observation of reverse Doppler effect in backward spin waves reflected off of surface acoustic waves. The spin waves are excited in a yttrium iron garnet (YIG) film. Simultaneously, acoustic waves are also generated. The strain induced by the acoustic waves in the magnetostrictive YIG film results in the periodic modulation of the magnetic anisotropy in the film. Thus, in effect, a travelling Bragg grating for the spin waves is produced. The backward spin waves reflecting off...

  10. Non-Linear Excitation of Ion Acoustic Waves

    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....

  11. Nonlinear ion acoustic waves scattered by vortexes

    Ohno, Yuji

    2015-01-01

    The Kadomtsev--Petviashvili (KP) hierarchy is the archetype of infinite-dimensional integrable systems, which describes nonlinear ion acoustic waves in two-dimensional space. This remarkably ordered system resides on a singular submanifold (leaf) embedded in a larger phase space of more general ion acoustic waves (low-frequency electrostatic perturbations). The KP hierarchy is characterized not only by small amplitudes but also by irrotational (zero-vorticity) velocity fields. In fact, the KP equation is derived by eliminating vorticity at every order of the reductive perturbation. Here we modify the scaling of the velocity field so as to introduce a vortex term. The newly derived system of equations consists of a generalized three-dimensional KP equation and a two-dimensional vortex equation. The former describes `scattering' of vortex-free waves by ambient vortexes that are determined by the latter. We say that the vortexes are `ambient' because they do not receive reciprocal reactions from the waves (i.e.,...

  12. Broadband Acoustic Cloak for Ultrasound Waves

    Zhang, Shu; Fang, Nicholas

    2010-01-01

    Invisibility devices based on coordinate transformation have opened up a new field of considerable interest. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely serial inductors and shunt capacitors. Our experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow. Due to the non-resonant nature of the building elements, this low loss (~6dB/m) cylindrical cloak exhibits excellent invisibility over a broad frequency range from 52 to 64 kHz in the measurements. The low visibility of the cloaked object for underwater ultrasound shed a light on the fundamental understanding of ma...

  13. Measuring Acoustic Wave Transit Time in Furnace Based on Active Acoustic Source Signal

    Zhen Luo; Feng Tian; Xiao-Ping Sun

    2007-01-01

    Accurate measurement of transit time for acoustic wave between two sensors installed on two sides of a furnace is a key to implementing the temperature field measurement technique based on acoustical method. A new method for measuring transit time of acoustic wave based on active acoustic source signal is proposed in this paper, which includes the followings: the time when the acoustic source signal arrives at the two sensors is measured first; then, the difference of two arriving time arguments is computed, thereby we get the transit time of the acoustic wave between two sensors installed on the two sides of the furnace. Avoiding the restriction on acoustic source signal and background noise, the new method can get the transit time of acoustic wave with higher precision and stronger ability of resisting noise interference.

  14. Strongly driven ion acoustic waves in laser produced plasmas

    This paper present an experimental study of ion acoustic waves with wavenumbers corresponding to stimulated Brillouin scattering. Time resolved Thomson scattering in frequency and wavenumber space, has permitted to observe the dispersion relation of the waves as a function of the laser intensity. Apart from observing ion acoustic waves associated with a strong second component is observed at laser intensities above 1013Wcm-2

  15. Simulating acoustic waves in spotted stars

    Papini, Emanuele; Gizon, Laurent; Hanasoge, Shravan M

    2015-01-01

    Acoustic modes of oscillation are affected by stellar activity, however it is unclear how starspots contribute to these changes. Here we investigate the non-magnetic effects of starspots on global modes with angular degree $\\ell \\leq 2$ in highly active stars, and characterize the spot seismic signature on synthetic light curves. We perform 3D time-domain simulations of linear acoustic waves to study their interaction with a model starspot. We model the spot as a 3D change in the sound speed stratification with respect to a convectively stable stellar background, built from solar Model S. We perform a parametric study by considering different depths and perturbation amplitudes. Exact numerical simulations allow investigation of the wavefield-spot interaction beyond first order perturbation theory. The interaction of the axisymmetric modes with the starspot is strongly nonlinear. As mode frequency increases, the frequency shifts for radial modes exceed the value predicted by linear theory, while the shifts for...

  16. Acoustic field distribution of sawtooth wave with nonlinear SBE model

    For precise prediction of the acoustic field distribution of extracorporeal shock wave lithotripsy with an ellipsoid transducer, the nonlinear spheroidal beam equations (SBE) are employed to model acoustic wave propagation in medium. To solve the SBE model with frequency domain algorithm, boundary conditions are obtained for monochromatic and sawtooth waves based on the phase compensation. In numerical analysis, the influence of sinusoidal wave and sawtooth wave on axial pressure distributions are investigated

  17. Acoustic clouds: standing sound waves around a black hole analogue

    Benone, Carolina L; Herdeiro, Carlos; Radu, Eugen

    2014-01-01

    Under certain conditions sound waves in fluids experience an acoustic horizon with analogue properties to those of a black hole event horizon. In particular, a draining bathtub-like model can give rise to a rotating acoustic horizon and hence a rotating black hole (acoustic) analogue. We show that sound waves, when enclosed in a cylindrical cavity, can form stationary waves around such rotating acoustic black holes. These acoustic perturbations display similar properties to the scalar clouds that have been studied around Kerr and Kerr-Newman black holes; thus they are dubbed acoustic clouds. We make the comparison between scalar clouds around Kerr black holes and acoustic clouds around the draining bathtub explicit by studying also the properties of scalar clouds around Kerr black holes enclosed in a cavity. Acoustic clouds suggest the possibility of testing, experimentally, the existence and properties of black hole clouds, using analog models.

  18. Wave-Flow Interactions and Acoustic Streaming

    Chafin, Clifford E

    2016-01-01

    The interaction of waves and flows is a challenging topic where a complete resolution has been frustrated by the essential nonlinear features in the hydrodynamic case. Even in the case of EM waves in flowing media, the results are subtle. For a simple shear flow of constant n fluid, incident radiation is shown to be reflected and refracted in an analogous manner to Snell's law. However, the beam intensities differ and the system has an asymmetry in that an internal reflection gap opens at steep incident angles nearly oriented with the shear. For EM waves these effects are generally negligible in real systems but they introduce the topic at a reduced level of complexity of the more interesting acoustic case. Acoustic streaming is suggested, both from theory and experimental data, to be associated with vorticity generation at the driver itself. Bounds on the vorticity in bulk and nonlinear effects demonstrate that the bulk sources, even with attenuation, cannot drive such a strong flow. A review of the velocity...

  19. Dual-mode acoustic wave biosensors microarrays

    Auner, Gregory W.; Shreve, Gina; Ying, Hao; Newaz, Golam; Hughes, Chantelle; Xu, Jianzeng

    2003-04-01

    We have develop highly sensitive and selective acoustic wave biosensor arrays with signal analysis systems to provide a fingerprint for the real-time identification and quantification of a wide array of bacterial pathogens and environmental health hazards. We have developed an unique highly sensitive dual mode acoustic wave platform prototype that, when combined with phage based selective detection elements, form a durable bacteria sensor. Arrays of these new real-time biosensors are integrated to form a biosensor array on a chip. This research and development program optimizes advanced piezoelectric aluminum nitride wide bandgap semiconductors, novel micromachining processes, advanced device structures, selective phage displays development and immobilization techniques, and system integration and signal analysis technology to develop the biosensor arrays. The dual sensor platform can be programmed to sense in a gas, vapor or liquid environment by switching between acoustic wave resonate modes. Such a dual mode sensor has tremendous implications for applications involving monitoring of pathogenic microorganisms in the clinical setting due to their ability to detect airborne pathogens. This provides a number of applications including hospital settings such as intensive care or other in-patient wards for the reduction of nosocomial infections and maintenance of sterile environments in surgical suites. Monitoring for airborn pathogen transmission in public transportation areas such as airplanes may be useful for implementation of strategies for redution of airborn transmission routes. The ability to use the same sensor in the liquid sensing mode is important for tracing the source of airborn pathogens to local liquid sources. Sensing of pathogens in saliva will be useful for sensing oral pathogens and support of decision-making strategies regarding prevention of transmission and support of treatment strategies.

  20. Simulation of dust-acoustic waves

    The authors use molecular dynamics (MD) and particle-in-cell (PIC) simulation methods to investigate the dispersion relation of dust-acoustic waves in a one-dimensional, strongly coupled (Coulomb coupling parameter Λ = ratio of the Coulomb energy to the thermal energy = 120) dusty plasma. They study both cases where the dust is represented by a small number of simulation particles that form into a regular array structure (crystal limit) as well as where the dust is represented by a much larger number of particles (fluid limit)

  1. Surface acoustic wave propagation in graphene film

    Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals

  2. Surface acoustic wave propagation in graphene film

    Roshchupkin, Dmitry, E-mail: rochtch@iptm.ru; Plotitcyna, Olga; Matveev, Viktor; Kononenko, Oleg; Emelin, Evgenii; Irzhak, Dmitry [Institute of Microelectronics Technology and High-Purity Materials Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Ortega, Luc [Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS, UMR 8502, 91405 Orsay Cedex (France); Zizak, Ivo; Erko, Alexei [Institute for Nanometre Optics and Technology, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein Strasse 15, 12489 Berlin (Germany); Tynyshtykbayev, Kurbangali; Insepov, Zinetula [Nazarbayev University Research and Innovation System, 53 Kabanbay Batyr St., Astana 010000 (Kazakhstan)

    2015-09-14

    Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.

  3. Twisted Dust Acoustic Waves in Dusty Plasmas

    Shukla, P K

    2012-01-01

    We examine linear dust acoustic waves (DAWs) in a dusty plasma with strongly correlated dust grains, and discuss possibility of a twisted DA vortex beam carrying orbital angular momentum (OAM). For our purposes, we use the Boltzmann distributed electron and ion density perturbations, the dust continuity and generalized viscoelastic dust momentum equations, and Poisson's equation to obtain a dispersion relation for the modified DAWs. The effects of the polarization force, strong dust couplings, and dust charge fluctuations on the DAW spectrum are examined. Furthermore, we demonstrate that the DAW can propagate as a twisted vortex beam carrying OAM. A twisted DA vortex structure can trap and transport dust particles in dusty plasmas.

  4. An acoustic metasurface design for wave motion conversion of longitudinal waves to transverse waves using topology optimization

    Noguchi, Y.; Yamada, T.; Otomori, M.; Izui, K.; Nishiwaki, S.

    2015-11-01

    This letter presents an acoustic metasurface that converts longitudinal acoustic waves into transverse elastic waves in an acoustic-elastic coupled system. Metasurface configurations are obtained by a level set-based topology optimization method, and we describe the mechanism that changes the direction of the wave motion. Numerical examples of 2D problems with prescribed frequencies of incident acoustic waves are provided, and transverse elastic wave amplitudes are maximized by manipulating the propagation of the acoustic waves. Frequency analysis reveals that each of the different metasurface designs obtained for different wavelengths of incident waves provides peak response at the target frequency.

  5. The anisotropy of attenuation of acoustic waves in acoustic-optic crystals

    On the basis of experimental data on the attenuation of acoustic waves in crystals of lithium niobate and lithium tantalate the components of a complex elasticity tensor have been determined. The surfaces characterizing the anisotropy of the attenuation coefficient of longitudinal and transverse acoustic waves in these crystals were constructed. It is shown that the most noticeable change in the acoustic attenuation for all types of waves is observed when the direction of propagation of the acoustic wave changes from the [111] to [001] axis. (authors)

  6. Manipulation of transmitted wave front using ultrathin planar acoustic metasurfaces

    Zhai, Shilong; Chen, Huaijun; Ding, Changlin; Shen, Fangliang; Luo, Chunrong; Zhao, Xiaopeng

    2015-09-01

    Nowadays, the acoustic devices are developing toward miniaturization. However, conventional materials can hardly satisfy the requirements because of their large size and complex manufacturing process. The introduction of acoustic metasurfaces has broken these restrictions, as they are able to manipulate sound waves at will by utilizing ultrathin planar metamaterials. Here, a simple acoustic metasurface is designed and characterized, whose microstructure is constructed with a cavity filled with air and two elastic membranes on the ends of cavity. By appropriately optimizing the configurations of microstructures, the steering of transmitted wave trajectory is demonstrated, and some extraordinary phenomena are realized at 3.5 kHz, such as planar acoustic axicon, acoustic lens, the conversion from spherical waves to plane waves, and the transformation from propagating waves to surface waves.

  7. Mechanism of an acoustic wave impact on steel during solidification

    K. Nowacki; P. Musiał; T. Lis

    2013-01-01

    Acoustic steel processing in an ingot mould may be the final stage in the process of quality improvement of a steel ingot. The impact of radiation and cavitation pressure as well as the phenomena related to the acoustic wave being emitted and delivered to liquid steel affect various aspects including the internal structure fragmentation, rigidity or density of steel. The article provides an analysis of the mechanism of impact of physical phenomena caused by an acoustic wave affecting the qual...

  8. Visualization of Surface Acoustic Waves in Thin Liquid Films

    Rambach, R. W.; Taiber, J.; C. M. L. Scheck; Meyer, C.; Reboud, J.; Cooper, J M; Franke, T.

    2016-01-01

    We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with anWe demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfl...

  9. Synthesis of anisotropic swirling surface acoustic waves by inverse filter, towards integrated generators of acoustical vortices

    Riaud, Antoine; Charron, Eric; Bussonnière, Adrien; Matar, Olivier Bou

    2015-01-01

    From radio-electronics signal analysis to biological samples actuation, surface acoustic waves (SAW) are involved in a multitude of modern devices. Despite this versatility, SAW transducers developed up to date only authorize the synthesis of the most simple standing or progressive waves such as plane and focused waves. In particular, acoustical integrated sources able to generate acoustical vortices (the analogue of optical vortices) are missing. In this work, we propose a flexible tool based on inverse filter technique and arrays of SAW transducers enabling the synthesis of prescribed complex wave patterns at the surface of anisotropic media. The potential of this setup is illustrated by the synthesis of a 2D analog of 3D acoustical vortices, namely "swirling surface acoustic waves". Similarly to their 3D counterpart, they appear as concentric structures of bright rings with a phase singularity in their center resulting in a central dark spot. Swirling SAW can be useful in fragile sensors whose neighborhood...

  10. Raising Photoemission Efficiency with Surface Acoustic Waves

    A. Afanasev, F. Hassani, C.E. Korman, V.G. Dudnikov, R.P. Johnson, M. Poelker, K.E.L. Surles-Law

    2012-07-01

    We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.

  11. Ion-acoustic cnoidal waves in a quantum plasma

    Mahmood, S. [Physics Institute, Federal University of Rio Grande do Sul, RS, Porto Alegre 915051-970 (Brazil); Theoretical Physics Division (TPD), PINSTECH P.O. Nilore, Islamabad 44000 (Pakistan); Haas, F. [Physics Institute, Federal University of Rio Grande do Sul, RS, Porto Alegre 915051-970 (Brazil)

    2014-10-15

    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{sub 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.

  12. Ion-acoustic cnoidal waves in a quantum plasma

    Mahmood, Shahzad

    2016-01-01

    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.

  13. Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms

    Lay, Erin H.; Shao, Xuan-Min; Kendrick, Alexander K.; Carrano, Charles S.

    2015-07-01

    Acoustic waves with periods of 2-4 min and gravity waves with periods of 6-16 min have been detected at ionospheric heights (250-350 km) using GPS total electron content measurements. The area disturbed by these waves and the wave amplitudes have been associated with underlying thunderstorm activity. A statistical study comparing Next Generation Weather Radar thunderstorm measurements with ionospheric acoustic and gravity waves in the midlatitude U.S. Great Plains region was performed for the time period of May-July 2005. An increase of ionospheric acoustic wave disturbed area and amplitude is primarily associated with large thunderstorms (mesoscale convective systems). Ionospheric gravity wave disturbed area and amplitude scale with thunderstorm activity, with even small storms (i.e., individual storm cells) producing an increase of gravity waves.

  14. Wind, waves, and acoustic background levels at Station ALOHA

    Duennebier, Fred K.; Lukas, Roger; Nosal, Eva-Marie; Aucan, JéRome; Weller, Robert A.

    2012-03-01

    Frequency spectra from deep-ocean near-bottom acoustic measurements obtained contemporaneously with wind, wave, and seismic data are described and used to determine the correlations among these data and to discuss possible causal relationships. Microseism energy appears to originate in four distinct regions relative to the hydrophone: wind waves above the sensors contribute microseism energy observed on the ocean floor; a fraction of this local wave energy propagates as seismic waves laterally, and provides a spatially integrated contribution to microseisms observed both in the ocean and on land; waves in storms generate microseism energy in deep water that travels as seismic waves to the sensor; and waves reflected from shorelines provide opposing waves that add to the microseism energy. Correlations of local wind speed with acoustic and seismic spectral time series suggest that the local Longuet-Higgins mechanism is visible in the acoustic spectrum from about 0.4 Hz to 80 Hz. Wind speed and acoustic levels at the hydrophone are poorly correlated below 0.4 Hz, implying that the microseism energy below 0.4 Hz is not typically generated by local winds. Correlation of ocean floor acoustic energy with seismic spectra from Oahu and with wave spectra near Oahu imply that wave reflections from Hawaiian coasts, wave interactions in the deep ocean near Hawaii, and storms far from Hawaii contribute energy to the seismic and acoustic spectra below 0.4 Hz. Wavefield directionality strongly influences the acoustic spectrum at frequencies below about 2 Hz, above which the acoustic levels imply near-isotropic surface wave directionality.

  15. Propagation of plate acoustic waves in contact with fluid medium

    Ghatadi Suraji, Nagaraj

    The characteristics of acoustic waves propagating in thin piezoelectric plates in the presence of a fluid medium contacting one or both of the plate surfaces are investigated. If the velocity of plate wave in the substrate is greater than velocity of bulk wave in the fluid, then a plate acoustic wave (PAW) traveling in the substrate will radiate a bulk acoustic wave (BAW) in the fluid. It is found that, under proper conditions, efficient conversion of energy from plate acoustic waves to bulk acoustic waves and vice versa can be obtained. For example, using the fundamental anti symmetric plate wave mode (A0 mode) propagating in a lithium niobate substrate and water as the fluid, total mode conversion loss (PAW to BAW and back from BAW to PAW) of less than 3 dB has been obtained. This mode conversion principle can be used to realize miniature, high efficiency transducers for use in ultrasonic flow meters. Similar type of transducer based on conversion of energy from surface acoustic wave (SAW) to bulk acoustic wave (BAW) has been developed previously. The use of plate waves has several advantages. Since the energy of plate waves is present on both plate surfaces, the inter digital transducer (IDT) can be on the surface opposite from that which is in contact with the fluid. This protects the IDT from possible damage due to the fluid and also simplifies the job of making electrical connections to the IDT. Another advantage is that one has wider choice of substrate materials with plate waves than is the case with SAWs. Preliminary calculations indicate that the mode conversion principle can also be used to generate and detect ultrasonic waves in air. This has potential applications for realizing transducers for use in non-contact ultrasonic's. The design of an ASIC (Application Specific Integrated Circuit) chip containing an amplifier and frequency counter for use with ultrasonic transducers is also presented in this thesis.

  16. Electro-acoustic solitary waves in dusty plasmas

    present a rigorous theoretical investigation of electro- acoustic [particularly, dust-ion acoustic (DIA) and dust-acoustic (DA)] solitary waves in dusty plasmas. We employ the reductive perturbation method for small but finite amplitude solitary waves as well as the pseudo-potential approach for arbitrary amplitude ones. We also analyze the effects of non-planar geometry and dust charge fluctuations on both DIA and DA solitary waves, the effect of finite ion-temperature on DIA solitary waves, and the effects of dust-fluid temperature and non-isothermal ion distributions on DA solitary waves. It has been reported that these effects do not only significantly modify the basic features of DIA or DA solitary waves, but also introduce some important new features. The basic features and the underlying physics of DIA and DA solitary waves, which are relevant to space and laboratory dusty plasmas, are briefly discussed. (author)

  17. Controlling acoustic-wave propagation through material anisotropy

    Tehranian, Aref; Amirkhizi, Alireza V.; Irion, Jeffrey; Isaacs, Jon; Nemat-Nasser, Sia

    2009-03-01

    Acoustic-wave velocity is strongly direction dependent in an anisotropic medium. This can be used to design composites with preferred acoustic-energy transport characteristics. In a unidirectional fiber-glass composite, for example, the preferred direction corresponds to the fiber orientation which is associated with the highest stiffness and which can be used to guide the momentum and energy of the acoustic waves either away from or toward a region within the material, depending on whether one wishes to avoid or harvest the corresponding stress waves. The main focus of this work is to illustrate this phenomenon using numerical simulations and then check the results experimentally.

  18. A metasurface carpet cloak for electromagnetic, acoustic and water waves

    Yihao Yang; Huaping Wang; Faxin Yu; Zhiwei Xu; Hongsheng Chen

    2016-01-01

    We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the re...

  19. Theoretical and Experimental Study on the Acoustic Wave Energy After the Nonlinear Interaction of Acoustic Waves in Aqueous Media

    兰朝凤; 李凤臣; 陈欢; 卢迪; 杨德森; 张梦

    2015-01-01

    Based on the Burgers equation and Manley-Rowe equation, the derivation about nonlinear interaction of the acoustic waves has been done in this paper. After nonlinear interaction among the low-frequency weak waves and the pump wave, the analytical solutions of acoustic waves’ amplitude in the field are deduced. The relationship between normalized energy of high-frequency and the change of acoustic energy before and after the nonlinear interaction of the acoustic waves is analyzed. The experimental results about the changes of the acoustic energy are presented. The study shows that new frequencies are generated and the energies of the low-frequency are modulated in a long term by the pump waves, which leads the energies of the low-frequency acoustic waves to change in the pulse trend in the process of the nonlinear interaction of the acoustic waves. The increase and decrease of the energies of the low-frequency are observed under certain typical conditions, which lays a foundation for practical engineering applications.

  20. Waveform inversion of acoustic waves for explosion yield estimation

    Kim, K.; Rodgers, A.

    2016-07-01

    We present a new waveform inversion technique to estimate the energy of near-surface explosions using atmospheric acoustic waves. Conventional methods often employ air blast models based on a homogeneous atmosphere, where the acoustic wave propagation effects (e.g., refraction and diffraction) are not taken into account, and therefore, their accuracy decreases with increasing source-receiver distance. In this study, three-dimensional acoustic simulations are performed with a finite difference method in realistic atmospheres and topography, and the modeled acoustic Green's functions are incorporated into the waveform inversion for the acoustic source time functions. The strength of the acoustic source is related to explosion yield based on a standard air blast model. The technique was applied to local explosions (structure. The presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.

  1. Effect of acoustic field parameters on arc acoustic binding during ultrasonic wave-assisted arc welding.

    Xie, Weifeng; Fan, Chenglei; Yang, Chunli; Lin, Sanbao

    2016-03-01

    As a newly developed arc welding method, power ultrasound has been successfully introduced into arc and weld pool during ultrasonic wave-assisted arc welding process. The advanced process for molten metals can be realized by utilizing additional ultrasonic field. Under the action of the acoustic wave, the plasma arc as weld heat source is regulated and its characteristics make an obvious change. Compared with the conventional arc, the ultrasonic wave-assisted arc plasma is bound significantly and becomes brighter. To reveal the dependence of the acoustic binding force on acoustic field parameters, a two-dimensional acoustic field model for ultrasonic wave-assisted arc welding device is established. The influences of the radiator height, the central pore radius, the radiator radius, and curvature radius or depth of concave radiator surface are discussed using the boundary element method. Then the authors analyze the resonant mode by this relationship curve between acoustic radiation power and radiator height. Furthermore, the best acoustic binding ability is obtained by optimizing the geometric parameters of acoustic radiator. In addition, three concave radiator surfaces including spherical cap surface, paraboloid of revolution, and rotating single curved surface are investigated systematically. Finally, both the calculation and experiment suggest that, to obtain the best acoustic binding ability, the ultrasonic wave-assisted arc welding setup should be operated under the first resonant mode using a radiator with a spherical cap surface, a small central pore, a large section radius and an appropriate curvature radius. PMID:26558995

  2. Nonlinear propagation and control of acoustic waves in phononic superlattices

    Jiménez, Noé; Picó, Rubén; García-Raffi, Lluís M; Sánchez-Morcillo, Víctor J

    2015-01-01

    The propagation of intense acoustic waves in a one-dimensional phononic crystal is studied. The medium consists in a structured fluid, formed by a periodic array of fluid layers with alternating linear acoustic properties and quadratic nonlinearity coefficient. The spacing between layers is of the order of the wavelength, therefore Bragg effects such as band-gaps appear. We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g. cubic) nonlinearities, or extremely linear media (where distortion can be cancelled). The presented ideas open a way towards the control of acoustic wave propagation in nonlinear regime.

  3. Acoustic-Gravity Waves Interacting with a Rectangular Trench

    Usama Kadri

    2014-01-01

    A mathematical solution of the two-dimensional linear problem of an acoustic-gravity wave interacting with a rectangular trench, in a compressible ocean, is presented. Expressions for the flow field on both sides of the trench are derived. The dynamic bottom pressure produced by the acoustic-gravity waves on both sides of the trench is measurable, though on the transmission side it decreases with the trench depth. A successful recording of the bottom pressures could assist in the early detect...

  4. Estimating propagation velocity through a surface acoustic wave sensor

    Xu, Wenyuan; Huizinga, John S.

    2010-03-16

    Techniques are described for estimating the propagation velocity through a surface acoustic wave sensor. In particular, techniques which measure and exploit a proper segment of phase frequency response of the surface acoustic wave sensor are described for use as a basis of bacterial detection by the sensor. As described, use of velocity estimation based on a proper segment of phase frequency response has advantages over conventional techniques that use phase shift as the basis for detection.

  5. Optical transition radiation in presence of acoustic waves

    Mkrtchyan, A R; Saharian, A A

    2009-01-01

    Transition radiation from relativistic electrons is investigated in an ultrasonic superlattice excited in a finite thickness plate. In the quasi-classical approximation formulae are derived for the vector potential of the electromagnetic field and for the spectral-angular distribution of the radiation intensity. The acoustic waves generate new resonance peaks in the spectral and angular distribution of the radiation intensity. The heights of the peaks can be tuned by choosing the parameters of the acoustic wave.

  6. Use of Acoustic Waves for Pulsating Water Jet Generation

    Foldyna, Josef

    1. Rijeka: InTech Open Access Publisher, 2011 - (Beghi, M.), s. 323-342 ISBN 978-953-307-572-3 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional research plan: CEZ:AV0Z30860518 Keywords : acoustic waves * pulsating water jet * technology Subject RIV: JQ - Machines ; Tools http://www.intechopen.com/books/acoustic-waves-from-microdevices-to-helioseismology

  7. Surface Acoustic Wave (SAW Vibration Sensors

    Jerzy Filipiak

    2011-12-01

    Full Text Available In the paper a feasibility study on the use of surface acoustic wave (SAW vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit.

  8. Surface acoustic wave devices for sensor applications

    Bo, Liu; Xiao, Chen; Hualin, Cai; Mohammad, Mohammad Ali; Xiangguang, Tian; Luqi, Tao; Yi, Yang; Tianling, Ren

    2016-02-01

    Surface acoustic wave (SAW) devices have been widely used in different fields and will continue to be of great importance in the foreseeable future. These devices are compact, cost efficient, easy to fabricate, and have a high performance, among other advantages. SAW devices can work as filters, signal processing units, sensors and actuators. They can even work without batteries and operate under harsh environments. In this review, the operating principles of SAW sensors, including temperature sensors, pressure sensors, humidity sensors and biosensors, will be discussed. Several examples and related issues will be presented. Technological trends and future developments will also be discussed. Project supported by the National Natural Science Foundation of China (Nos. 60936002, 61025021, 61434001, 61574083), the State Key Development Program for Basic Research of China (No. 2015CB352100), the National Key Project of Science and Technology (No. 2011ZX02403-002) and the Special Fund for Agroscientific Research in the Public Interest of China (No. 201303107). M.A.M is additionally supported by the Postdoctoral Fellowship (PDF) program of the Natural Sciences and Engineering Research Council (NSERC) of Canada and the China Postdoctoral Science Foundation (CPSF).

  9. Nozzleless Spray Cooling Using Surface Acoustic Waves

    Ang, Kar Man; Yeo, Leslie; Friend, James; Hung, Yew Mun; Tan, Ming Kwang

    2015-11-01

    Due to its reliability and portability, surface acoustic wave (SAW) atomization is an attractive approach for the generation of monodispersed microdroplets in microfluidics devices. Here, we present a nozzleless spray cooling technique via SAW atomization with key advantage of downward scalability by simply increasing the excitation frequency. With generation of micron size droplets through surface destabilization using SAW, the clogging issues commonly encountered by spraying nozzle can be neutralized. Using deionised water, cooling is improved when the atomization rate is increased and the position of the device is optimized such that the atomized droplets can be easily seeded into the upstream of the flow circulation. Cooling is further improved with the use of nanofluids; a suspension of nanoparticles in water. By increasing nanoparticle mass concentration from 1% to 3%, cooling is enhanced due to the deposition and formation of nanoparticle clusters on heated surface and eventually increase the surface area. However, further increase the concentration to 10% reduces the cooling efficiency due to drastic increase in viscosity μ that leads to lower atomization rate which scales as ṁ ~μ - 1 / 2 .

  10. Acoustic Kappa-Density Fluctuation Waves in Suprathermal Kappa Function Fluids

    Collier, Michael R.; Roberts, Aaron; Vinas, Adolfo

    2007-01-01

    We describe a new wave mode similar to the acoustic wave in which both density and velocity fluctuate. Unlike the acoustic wave in which the underlying distribution is Maxwellian, this new wave mode occurs when the underlying distribution is a suprathermal kappa function and involves fluctuations in the power law index, kappa. This wave mode always propagates faster than the acoustic wave with an equivalent effective temperature and becomes the acoustic wave in the Maxwellian limit as kappa g...

  11. Electro-acoustic shock waves in dusty plasmas

    A rigorous theoretical investigation has been made of electro- acoustic [particularly, dust-ion acoustic (DIA) and dust-acoustic (DA)] shock waves in unmagnetized dusty plasmas. The reductive perturbation method has been employed for the study of the small but finite amplitude DIA and DA shock waves. It has been reported that the dust grain charge fluctuation can be one of the candidates for the source of dissipation, and can be responsible for the formation of DIA shock waves in an unmagnetized dusty plasma with static charged dust particles. It has also been reported that the strong co-relation among dust particles can be one of the candidates for the source of dissipation, and can be responsible for the formation of DA shock waves in an unmagnetized strongly coupled dusty plasma. The basic features and the underlying physics of DIA and DA shock waves, which are relevant to space and laboratory dusty plasmas, are briefly discussed. (author)

  12. Development of Surface Acoustic Wave Electronic Nose

    S.K. Jha

    2010-07-01

    Full Text Available The paper proposes an effective method to design and develop surface acoustic wave (SAW sensor array-based electronic nose systems for specific target applications. The paper suggests that before undertaking full hardware development empirically through hit and trial for sensor selection, it is prudent to develop accurate sensor array simulator for generating synthetic data and optimising sensor array design and pattern recognition system. The latter aspects are most time-consuming and cost-intensive parts in the development of an electronic nose system. This is because most of the electronic sensor platforms, circuit components, and electromechanical parts are available commercially-off-the-shelve (COTS, whereas knowledge about specific polymers and data analysis software are often guarded due to commercial or strategic interests. In this study, an 11-element SAW sensor array is modelled to detect and identify trinitrotoluene (TNT and dinitrotoluene (DNT explosive vapours in the presence of toluene, benzene, di-methyl methyl phosphonate (DMMP and humidity as interferents. Additive noise sources and outliers were included in the model for data generation. The pattern recognition system consists of: (i a preprocessor based on logarithmic data scaling, dimensional autoscaling, and singular value decomposition-based denoising, (ii principal component analysis (PCA-based feature extractor, and (iii an artificial neural network (ANN classifier. The efficacy of this approach is illustrated by presenting detailed PCA analysis and classification results under varied conditions of noise and outlier, and by analysing comparative performance of four classifiers (neural network, k-nearest neighbour, naïve Bayes, and support vector machine.Defence Science Journal, 2010, 60(4, pp.364-376, DOI:http://dx.doi.org/10.14429/dsj.60.493

  13. Surface wave patterns on acoustically levitated viscous liquid alloys

    Hong, Z. Y.; Yan, N.; Geng, D. L.; Wei, B.

    2014-04-01

    We demonstrate two different kinds of surface wave patterns on viscous liquid alloys, which are melted and solidified under acoustic levitation condition. These patterns are consistent with the morphologies of standing capillary waves and ensembles of oscillons, respectively. The rapid solidification of two-dimensional liquid alloy surfaces may hold them down.

  14. INTERFERENCE FRINGES OF SOLAR ACOUSTIC WAVES AROUND SUNSPOTS

    Chou, Dean-Yi; Zhao Hui; Yang, Ming-Hsu; Liang, Zhi-Chao, E-mail: chou@phys.nthu.edu.tw [Physics Department, National Tsing Hua University, Hsinchu, Taiwan (China)

    2012-10-20

    Solar acoustic waves are scattered by a sunspot due to the interaction between the acoustic waves and the sunspot. The sunspot, excited by the incident wave, generates the scattered wave. The scattered wave is added to the incident wave to form the total wave around the sunspot. The interference fringes between the scattered wave and the incident wave are visible in the intensity of the total wave because the coherent time of the incident wave is of the order of a wave period. The strength of the interference fringes anti-correlates with the width of temporal spectra of the incident wave. The separation between neighboring fringes increases with the incident wavelength and the sunspot size. The strength of the fringes increases with the radial order n of the incident wave from n = 0 to n = 2, and then decreases from n = 2 to n = 5. The interference fringes play a role analogous to holograms in optics. This study suggests the feasibility of using the interference fringes to reconstruct the scattered wavefields of the sunspot, although the quality of the reconstructed wavefields is sensitive to the noise and errors in the interference fringes.

  15. Propagation of Acoustic Waves in Troposphere and Stratosphere

    Kashyap, J M

    2016-01-01

    Acoustic waves are those waves which travel with the speed of sound through a medium. H. Lamb has derived a cutoff frequency for stratified and isothermal medium for the propagation of acoustic waves. In order to find the cutoff frequency many methods were introduced after Lamb's work. In this paper, we have chosen the method to determine cutoff frequencies for acoustic waves propagating in non-isothermal media. This turning point frequency method can be applied to various atmospheres like solar atmosphere, stellar atmosphere, earth's atmosphere etc. Here, we have analytically derived the cutoff frequency and have graphically analyzed and compared with the Lamb's cut-off frequencyfor earth's troposphere, lower and upper stratosphere.

  16. Thermo-acoustic engineering of silicon microresonators via evanescent waves

    A temperature-compensated silicon micromechanical resonator with a quadratic temperature characteristic is realized by acoustic engineering. Energy-trapped resonance modes are synthesized by acoustic coupling of propagating and evanescent extensional waves in waveguides with rectangular cross section. Highly different temperature sensitivity of propagating and evanescent waves is used to engineer the linear temperature coefficient of frequency. The resulted quadratic temperature characteristic has a well-defined turn-over temperature that can be tailored by relative energy distribution between propagating and evanescent acoustic fields. A 76 MHz prototype is implemented in single crystal silicon. Two high quality factor and closely spaced resonance modes, created from efficient energy trapping of extensional waves, are excited through thin aluminum nitride film. Having different evanescent wave constituents and energy distribution across the device, these modes show different turn over points of 67 °C and 87 °C for their quadratic temperature characteristic

  17. Propagation of acoustic gravity waves excited by explosions

    Acoustic gravity waves excited by low-altitude nuclear explosions have been observed in the ionosphere, by H.F. Doppler soundings, at horizontal distances from the source between 100 and 1200 km. The characteristics of the initial shock wave, which is observed at short range, are progressively replaced by those of the atmospheric wave guide. In particular, the dispersion properties of the signal observed in the ionosphere at long range are those of the first acoustic and gravity modes. Detailed study of the propagation times to middle and long range shows that the wave guide is mainly excited by the focalisation of acoustic energy which is produced by non-linear mechanisms at an altitude of about 100 km and at a small horizontal distance from the explosion

  18. Quantum ion-acoustic solitary waves in weak relativistic plasma

    Biswajit Sahu

    2011-06-01

    Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized twospecies relativistic quantum plasma system, comprised of electrons and ions. The one-dimensional quantum hydrodynamic model (QHD) is used to obtain a deformed Korteweg–de Vries (dKdV) equation by reductive perturbation method. A linear dispersion relation is also obtained taking into account the relativistic effect. The properties of quantum ion-acoustic solitary waves, obtained from the deformed KdV equation, are studied taking into account the quantum mechanical effects in the weak relativistic limit. It is found that relativistic effects significantly modify the properties of quantum ion-acoustic waves. Also the effect of the quantum parameter on the nature of solitary wave solutions is studied in some detail.

  19. Ionospheric signatures of acoustic waves generated by transient tropospheric forcing

    Zettergren, M. D.; Snively, J. B.

    2013-10-01

    Acoustic waves generated by tropospheric sources may attain significant amplitudes in the thermosphere and overlying ionosphere. Although they are weak precursors to gravity waves in the mesosphere below, acoustic waves may achieve temperature and vertical wind perturbations on the order of approximately tens of Kelvin and m/s throughout the E and F regions. Their perturbations to total electron content are predicted to be detectable by ground-based radar and GPS receivers; they also drive field-aligned currents that may be detectable in situ via magnetometers. Although transient and short lived, ionospheric signatures of acoustic waves may provide new and quantitative insight into the forcing of the upper atmosphere from below.

  20. Thermo-acoustic engineering of silicon microresonators via evanescent waves

    Tabrizian, R., E-mail: rtabrizi@umich.edu [Electrical Engineering and Computer Science Department, University of Michigan, Ann Arbor, Michigan 48109 (United States); Ayazi, F. [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30308 (United States)

    2015-06-29

    A temperature-compensated silicon micromechanical resonator with a quadratic temperature characteristic is realized by acoustic engineering. Energy-trapped resonance modes are synthesized by acoustic coupling of propagating and evanescent extensional waves in waveguides with rectangular cross section. Highly different temperature sensitivity of propagating and evanescent waves is used to engineer the linear temperature coefficient of frequency. The resulted quadratic temperature characteristic has a well-defined turn-over temperature that can be tailored by relative energy distribution between propagating and evanescent acoustic fields. A 76 MHz prototype is implemented in single crystal silicon. Two high quality factor and closely spaced resonance modes, created from efficient energy trapping of extensional waves, are excited through thin aluminum nitride film. Having different evanescent wave constituents and energy distribution across the device, these modes show different turn over points of 67 °C and 87 °C for their quadratic temperature characteristic.

  1. Separation of acoustic waves in isentropic flow perturbations

    Henke, Christian, E-mail: christian.henke@atlas-elektronik.com

    2015-04-15

    The present contribution investigates the mechanisms of sound generation and propagation in the case of highly-unsteady flows. Based on the linearisation of the isentropic Navier–Stokes equation around a new pathline-averaged base flow, it is demonstrated for the first time that flow perturbations of a non-uniform flow can be split into acoustic and vorticity modes, with the acoustic modes being independent of the vorticity modes. Therefore, we can propose this acoustic perturbation as a general definition of sound. As a consequence of the splitting result, we conclude that the present acoustic perturbation is propagated by the convective wave equation and fulfils Lighthill’s acoustic analogy. Moreover, we can define the deviations of the Navier–Stokes equation from the convective wave equation as “true” sound sources. In contrast to other authors, no assumptions on a slowly varying or irrotational flow are necessary. Using a symmetry argument for the conservation laws, an energy conservation result and a generalisation of the sound intensity are provided. - Highlights: • First splitting of non-uniform flows in acoustic and non-acoustic components. • These result leads to a generalisation of sound which is compatible with Lighthill’s acoustic analogy. • A closed equation for the generation and propagation of sound is given.

  2. Separation of acoustic waves in isentropic flow perturbations

    The present contribution investigates the mechanisms of sound generation and propagation in the case of highly-unsteady flows. Based on the linearisation of the isentropic Navier–Stokes equation around a new pathline-averaged base flow, it is demonstrated for the first time that flow perturbations of a non-uniform flow can be split into acoustic and vorticity modes, with the acoustic modes being independent of the vorticity modes. Therefore, we can propose this acoustic perturbation as a general definition of sound. As a consequence of the splitting result, we conclude that the present acoustic perturbation is propagated by the convective wave equation and fulfils Lighthill’s acoustic analogy. Moreover, we can define the deviations of the Navier–Stokes equation from the convective wave equation as “true” sound sources. In contrast to other authors, no assumptions on a slowly varying or irrotational flow are necessary. Using a symmetry argument for the conservation laws, an energy conservation result and a generalisation of the sound intensity are provided. - Highlights: • First splitting of non-uniform flows in acoustic and non-acoustic components. • These result leads to a generalisation of sound which is compatible with Lighthill’s acoustic analogy. • A closed equation for the generation and propagation of sound is given

  3. Oblique amplitude modulation of dust-acoustic plasma waves

    Kourakis, I.; Shukla, P. K.

    2004-01-01

    Theoretical and numerical studies are presented of the nonlinear amplitude modulation of dust-acoustic (DA) waves propagating in an unmagnetized three component, weakly-coupled, fully ionized plasma consisting of electrons, positive ions and charged dust particles, considering perturbations oblique to the carrier wave propagation direction. The stability analysis, based on a nonlinear Schroedinger-type equation (NLSE), shows that the wave may become unstable; the stability criteria depend on ...

  4. Transmission Line Based Metamaterials for Acoustic Waves

    Bongard, Frédéric; Lissek, Hervé; Mosig, Juan Ramon

    2011-01-01

    We present our recent work on a one-dimensional acoustic negative refractive index metamaterial based on the concept of dual transmission line extensively investigated in microwave engineering. The proposed structure consists of an acoustic waveguide periodically loaded with membranes realizing the function of series “capacitances” and transversally connected open channels realizing shunt “inductances”. It exhibits a negative refractive index band over almost one octave, from 0.6 to 1 kHz. Us...

  5. Acoustic tweezers via sub–time-of-flight regime surface acoustic waves

    Collins, David J.; Devendran, Citsabehsan; Ma, Zhichao; Ng, Jia Wei; Neild, Adrian; Ai, Ye

    2016-01-01

    Micrometer-scale acoustic waves are highly useful for refined optomechanical and acoustofluidic manipulation, where these fields are spatially localized along the transducer aperture but not along the acoustic propagation direction. In the case of acoustic tweezers, such a conventional acoustic standing wave results in particle and cell patterning across the entire width of a microfluidic channel, preventing selective trapping. We demonstrate the use of nanosecond-scale pulsed surface acoustic waves (SAWs) with a pulse period that is less than the time of flight between opposing transducers to generate localized time-averaged patterning regions while using conventional electrode structures. These nodal positions can be readily and arbitrarily positioned in two dimensions and within the patterning region itself through the imposition of pulse delays, frequency modulation, and phase shifts. This straightforward concept adds new spatial dimensions to which acoustic fields can be localized in SAW applications in a manner analogous to optical tweezers, including spatially selective acoustic tweezers and optical waveguides. PMID:27453940

  6. Spin wave acoustics of antiferromagnetic structures as magnetoacoustic metamaterials

    Gulyaev, Yurii V; Tarasenko, Sergei V; Shavrov, Vladimir G

    2011-06-30

    This is a review of research results on conditions under which spatially restricted low-temperature antiferromagnets and their composites can be considered as a special class of acoustic magnetic metamaterials (magnetoacoustic metamaterials). In these, the dynamic magnetoacoustic interaction produces a number of effects that are acoustic analogs of polariton effects and which are currently intensively studied in nonmagnetic acoustic metamaterials. It is shown that the elastostatic approach to the analysis of the magnetoelastic dynamics of spatially restricted compensated magnetics is an effective tool in the search for new types of resonance acoustic anomalies, part of which are typical of the magnetostatic spin wave physics (elastostatic bulk and surface spin waves, nonuniform spin-spin resonances with their participation, etc.). (reviews of topical problems)

  7. Spin wave acoustics of antiferromagnetic structures as magnetoacoustic metamaterials

    This is a review of research results on conditions under which spatially restricted low-temperature antiferromagnets and their composites can be considered as a special class of acoustic magnetic metamaterials (magnetoacoustic metamaterials). In these, the dynamic magnetoacoustic interaction produces a number of effects that are acoustic analogs of polariton effects and which are currently intensively studied in nonmagnetic acoustic metamaterials. It is shown that the elastostatic approach to the analysis of the magnetoelastic dynamics of spatially restricted compensated magnetics is an effective tool in the search for new types of resonance acoustic anomalies, part of which are typical of the magnetostatic spin wave physics (elastostatic bulk and surface spin waves, nonuniform spin-spin resonances with their participation, etc.). (reviews of topical problems)

  8. Dissipation of acoustic-gravity waves: an asymptotic approach.

    Godin, Oleg A

    2014-12-01

    Acoustic-gravity waves in the middle and upper atmosphere and long-range propagation of infrasound are strongly affected by air viscosity and thermal conductivity. To characterize the wave dissipation, it is typical to consider idealized environments, which admit plane-wave solutions. Here, an asymptotic approach is developed that relies instead on the assumption that spatial variations of environmental parameters are gradual. It is found that realistic assumptions about the atmosphere lead to rather different predictions for wave damping than do the plane-wave solutions. A modification to the Sutherland-Bass model of infrasound absorption is proposed. PMID:25480091

  9. Second harmonic interference patterns of ion-acoustic waves

    The interaction of two weakly nonlinear sinusoidal ion-acoustic waves produces mainly a fundamental and a second harmonic diffraction pattern. The former is similar to the double slit pattern well known from physical optics, while it is found that the latter resembles a linear pattern generated by the superposition of three waves. The third wave is formed by mutual nonlinear interaction of the two fundamental waves. The intensity of the second harmonic pattern is modulated by the recurrence effect and it depends also on the angle between the local wave vectors. (author)

  10. High coupling materials for thin film bulk acoustic wave resonators

    Conde, Janine

    2009-01-01

    Radio frequency (RF) filters based on bulk acoustic wave resonances in piezoelectric thin films have become indispensable components in mobile communications. The currently used material, AlN, exhibits many excellent properties for this purpose. However, its bandwidth is often a limiting factor. In addition, no tuning is possible with AlN. Ferroelectrics would offer both larger coupling to achieve larger bandwidths, and tunability. However, their acoustic properties are not well known, especi...

  11. Self excitation of second harmonic ion-acoustic waves in a weakly magnetized plasma

    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

  12. On acoustic wave generation in uniform shear flow

    Gogoberidze, G.

    2016-07-01

    The linear dynamics of acoustic waves and vortices in uniform shear flow is studied. For flows with very low shear rates, the dynamics of perturbations is adiabatic and can be described by the WKB approximation. However, for flows with moderate and high shear rates the WKB approximation is not appropriate, and alternative analysis shows that two important phenomena occur: acoustic wave over-reflection and wave generation by vortices. The later phenomenon is a known linear mechanisms for sound generation in shear flows, a mechanism that is related to the continuous spectrum that arises in linear shear flow dynamics. A detailed analytical study of these phenomena is performed and the main quantitative and qualitative characteristics of the radiated acoustic field are obtained and analyzed.

  13. Resonance scattering of radio waves in the acoustically disturbed ionosphere

    It is known that acoustic waves are excited in the atmosphere for a variety of reasons, including seismic oscillations of the earth's surface as a result of earthquakes, volcanic eruptions, explosions, and in the operation of other powerful sources of natural or artificial origin. When sound waves are sufficiently intense, they can create disturbances in the electron density at ionospheric heights. In this paper, we consider the properties of radio wave scattering off such disturbances created by infrasound waves, i.e., we consider Mandel'shtam-Brillouin scattering in the ionosphere. The authors discuss the possibility of a radiophysical enhancement of the effect connected with the phenomenon of resonance scattering of the radiowaves off the disturbances created in the medium by the acoustic wave

  14. Effect of Thermal Conduction on Acoustic Waves in Coronal Loops

    Bogdan, T. J.

    2006-05-01

    The influence of classical (Spitzer) thermal conduction on longitudinal acoustic waves in a coronal loop is determined through an idealized but exactly solvable model. The model consists of an isothermal, stratified (constant gravity) atmosphere in which a monochromatic acoustic wave, traveling in the direction of decreasing density, is imposed throughout the lower half of the atmosphere. Based on the linearized equations of motion, the complete steady state (t-->∞) solution is obtained. In addition to the imposed driving wave, the solution also contains reflected and transmitted acoustic and thermal conduction waves. The mode transformation and mixing occurs in the vicinity of the atmospheric layer where the gas pressure passes through a critical value set by the magnitude of the thermal conduction and other model parameters. For 5 minute waves in a million degree loop, this critical pressure is on the order of 8×10-4 in cgs units. Since the apex gas pressure of many coronal loops of current interest is thought to be comfortably in excess of this value, mode mixing and transformation is not likely to be a relevant factor for understanding acoustic waves in these structures. On the other hand, enhanced thermal conductivity as a result of plasma instabilities, for example, could revive the importance of this mechanism for coronal loops. If this mixing layer is present, the calculations show that the pair of thermal conduction waves invariably gains the overwhelming majority of the energy flux of the incoming acoustic wave. This energy is rapidly dissipated in the neighborhood of the mixing layer.

  15. A metasurface carpet cloak for electromagnetic, acoustic and water waves

    Yang, Yihao; Wang, Huaping; Yu, Faxin; Xu, Zhiwei; Chen, Hongsheng

    2016-01-01

    We propose a single low-profile skin metasurface carpet cloak to hide objects with arbitrary shape and size under three different waves, i.e., electromagnetic (EM) waves, acoustic waves and water waves. We first present a metasurface which can control the local reflection phase of these three waves. By taking advantage of this metasurface, we then design a metasurface carpet cloak which provides an additional phase to compensate the phase distortion introduced by a bump, thus restoring the reflection waves as if the incident waves impinge onto a flat mirror. The finite element simulation results demonstrate that an object can be hidden under these three kinds of waves with a single metasurface cloak.

  16. Analysis of Acoustic Wave Propagation in a Thin Moving Fluid

    Joly, Patrick; Weder, Ricardo

    2009-01-01

    We study the propagation of acoustic waves in a fluid that is contained in a thin two-dimensional tube, and that it is moving with a velocity profile that only depends on the transversal coordinate of the tube. The governing equations are the Galbrun equations, or, equivalently, the linearized Euler equations. We analyze the approximate model that was recently derived by Bonnet-Bendhia, Durufl\\'e and Joly to describe the propagation of the acoustic waves in the limit when the width of the tub...

  17. Amplification of acoustic evanescent waves using metamaterial slabs.

    Park, Choon Mahn; Park, Jong Jin; Lee, Seung Hwan; Seo, Yong Mun; Kim, Chul Koo; Lee, Sam H

    2011-11-01

    We amplified acoustic evanescent waves using metamaterial slabs with a negative effective density. For the amplifying effect of the slab to overcome the dissipation, it is necessary that the imaginary part of the effective density is much smaller than the real part, a condition not satisfied so far. We report the construction of membrane-based two-dimensional negative-density metamaterials which exhibited remarkably small dissipation. Using a slab of this metamaterial we realized a 17-fold net amplitude gain at a remote distance from the evanescent wave source. Potential applications include acoustic superlensing. PMID:22181610

  18. An Unconditionally Stable Method for Solving the Acoustic Wave Equation

    Zhi-Kai Fu

    2015-01-01

    Full Text Available An unconditionally stable method for solving the time-domain acoustic wave equation using Associated Hermit orthogonal functions is proposed. The second-order time derivatives in acoustic wave equation are expanded by these orthogonal basis functions. By applying Galerkin temporal testing procedure, the time variable can be eliminated from the calculations. The restriction of Courant-Friedrichs-Levy (CFL condition in selecting time step for analyzing thin layer can be avoided. Numerical results show the accuracy and the efficiency of the proposed method.

  19. Theoretical analysis of leaky surface acoustic waves of point-focused acoustic lens and some experiments

    When a point-focused acoustic lens in the scanning acoustic microscope (SAM) is faced to test specimen and defocused to some extent, two effective echoes can be obtained. One is the echo of longitudinal wave, which is normally incident upon the specimen of an on-axis beam in the central region of the lens and is reflected normal to the lens surface, hence detected by the transducer. The other is of leaky surface acoustic waves(LSAW), which are mode converted front a narrow beam of off-axis longitudinal wave, then propagate across the surface of the specimen and reradiate at angles normal to the lens surface, thus detected by the transducer. These two echoes are either interfered or separated with each other depending ell the defocused distance. It turned out theoretically that the LSAW have a narrow focal spot in the central region of the point-focused acoustic lens, whose size is approximately 40% of the LSAW wavelength. On top of that, a wavelength of LSAW is about 50% short as that of longitudinal wave. So, It is expected that high resolution images can be obtained provided LSAW are used in the scanning acoustic microscope.

  20. Stimulated electron-acoustic-wave scattering in a laser plasma

    Intense laser-plasma interaction can be a source of various electronic instabilities. Recently, stimulated backscattering from a trapped electron-acoustic wave (SEAS) (D.S. Montgomery et al., Phys. Rev. Lett. 87, 155001 (2001)) was proposed to reinterpret spectra previously attributed to stimulated Raman scattering (SRS) from unrealistically low densities. By particle simulations in a uniform plasma layer, which is overdense for ordinary SRS, strong reflection by SEAS at the electron plasma frequency is found. Transient SEAS reflectivity pulsations are followed by strong relativistic heating of electrons. Physical conditions are explained by three-wave parametric coupling between laser light, standing backscattered wave and slow electron-acoustic wave. Regions in which SEAS reflection can dominate over SRS are singled out. (author)

  1. Reflection and Transmission of Acoustic Waves at Semiconductor - Liquid Interface

    J. N. Sharma

    2011-09-01

    Full Text Available The study of reflection and transmission characteristics of acoustic waves at the interface of a semiconductor halfspace underlying an inviscid liquid has been carried out. The reflection and transmission coefficients of reflected and transmitted waves have been obtained for quasi-longitudinal (qP wave incident at the interface from fluid to semiconductor. The numerical computations of reflection and transmission coefficients have been carried out with the help of Gauss elimination method by using MATLAB programming for silicon (Si, germanium (Ge and silicon nitride (Si3N4 semiconductors. In order to interpret and compare, the computer simulated results are plotted graphically. The study may be useful in semiconductors, seismology and surface acoustic wave (SAW devices in addition to engines of the space shuttles.

  2. Surface spin-electron acoustic waves in magnetically ordered metals

    Andreev, Pavel A

    2015-01-01

    Degenerate plasmas with motionless ions show existence of three surface waves: the Langmuir wave, the electromagnetic wave, and the zeroth sound. Applying the separated spin evolution quantum hydrodynamics to half-space plasma we demonstrate the existence of the surface spin-electron acoustic wave (SSEAW). We study dispersion of the SSEAW. We show that there is hybridization between the surface Langmuir wave and the SSEAW at rather small spin polarization. In the hybridization area the dispersion branches are located close to each other. In this area there is a strong interaction between these waves leading to the energy exchange. Consequently, generating the Langmuir waves with the frequencies close to hybridization area we can generate the SSEAWs. Thus, we report a method of creation of the SEAWs.

  3. Anisotropic metamaterials for full control of acoustic waves

    Christensen, Johan; García de Abajo, F. Javier

    2012-01-01

    We show that a holey anisotropic metamaterial can exert subwavelength control over sound waves beyond that achieved with naturally occurring materials [Nature Physics 3, 851 (2007)]. We predict that, for appropriate choices of geometrical parameters, these metamaterials support negative refraction, backward wave propagation along a direction opposite with respect to the acoustic energy flow, and subwavelength imaging [Nature Physics 7, 52 (2011)] with both the source and the image situated fa...

  4. Negative refraction and backward waves in layered acoustic metamaterials

    Christensen, Johan; García de Abajo, F. Javier

    2012-01-01

    We investigate layered acoustic metamaterials capable of exhibiting a wide variety of wave propagation phenomena, including backward and forward waves with and without negative refraction. The metamaterials are formed by periodically perforated hard plates, which we describe analytically in the limit of small holes compared to both the period and the separation between plates. In particular, we derive expressions for the index of refraction and the transmission and reflection coefficients of ...

  5. Numerical modelling of nonlinear full-wave acoustic propagation

    Velasco-Segura, Roberto; Rendón, Pablo L.

    2015-10-01

    The various model equations of nonlinear acoustics are arrived at by making assumptions which permit the observation of the interaction with propagation of either single or joint effects. We present here a form of the conservation equations of fluid dynamics which are deduced using slightly less restrictive hypothesis than those necessary to obtain the well known Westervelt equation. This formulation accounts for full wave diffraction, nonlinearity, and thermoviscous dissipative effects. A two-dimensional, finite-volume method using Roe's linearisation has been implemented to obtain numerically the solution of the proposed equations. This code, which has been written for parallel execution on a GPU, can be used to describe moderate nonlinear phenomena, at low Mach numbers, in domains as large as 100 wave lengths. Applications range from models of diagnostic and therapeutic HIFU, to parametric acoustic arrays and nonlinear propagation in acoustic waveguides. Examples related to these applications are shown and discussed.

  6. Numerical modelling of nonlinear full-wave acoustic propagation

    The various model equations of nonlinear acoustics are arrived at by making assumptions which permit the observation of the interaction with propagation of either single or joint effects. We present here a form of the conservation equations of fluid dynamics which are deduced using slightly less restrictive hypothesis than those necessary to obtain the well known Westervelt equation. This formulation accounts for full wave diffraction, nonlinearity, and thermoviscous dissipative effects. A two-dimensional, finite-volume method using Roe’s linearisation has been implemented to obtain numerically the solution of the proposed equations. This code, which has been written for parallel execution on a GPU, can be used to describe moderate nonlinear phenomena, at low Mach numbers, in domains as large as 100 wave lengths. Applications range from models of diagnostic and therapeutic HIFU, to parametric acoustic arrays and nonlinear propagation in acoustic waveguides. Examples related to these applications are shown and discussed

  7. Numerical modelling of nonlinear full-wave acoustic propagation

    Velasco-Segura, Roberto, E-mail: roberto.velasco@ccadet.unam.mx; Rendón, Pablo L., E-mail: pablo.rendon@ccadet.unam.mx [Grupo de Acústica y Vibraciones, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Ciudad Universitaria, Apartado Postal 70-186, C.P. 04510, México D.F., México (Mexico)

    2015-10-28

    The various model equations of nonlinear acoustics are arrived at by making assumptions which permit the observation of the interaction with propagation of either single or joint effects. We present here a form of the conservation equations of fluid dynamics which are deduced using slightly less restrictive hypothesis than those necessary to obtain the well known Westervelt equation. This formulation accounts for full wave diffraction, nonlinearity, and thermoviscous dissipative effects. A two-dimensional, finite-volume method using Roe’s linearisation has been implemented to obtain numerically the solution of the proposed equations. This code, which has been written for parallel execution on a GPU, can be used to describe moderate nonlinear phenomena, at low Mach numbers, in domains as large as 100 wave lengths. Applications range from models of diagnostic and therapeutic HIFU, to parametric acoustic arrays and nonlinear propagation in acoustic waveguides. Examples related to these applications are shown and discussed.

  8. Acoustic nonlinearity of ultrasonic wave by crack face contacting effect

    Nonlinear acoustic effect accompanied by the propagation of ultrasonic wave has been discussed from log time before and the effort to evaluate material degradation or degree of damage by measuring this effect has been tried in recent. The mechanism for the generation of nonlinear acoustic effect was proposed by several researchers and these previous studies have identified two primary sources of the nonlinearity. One source is the anharmonicity of lattice itself. The other source is associated with the contribution of dislocation displacement. In this paper, an another new source of nonlinearity generated due to the partial contact of crack face when the ultrasonic wave passes through tiny crack is considered. At first, the mechanism of the generation of acoustic nonlinearity at the crack face by half wave model was explained and the relationship between the separation distance of crack faces and. the magnitude of nonlinearity was investigated quantitatively by fourier transform of the half wave and computer simulation. In next, the existence of the proposed new source of nonlinearity at crack face was shown experimentally in the actual case, SAM signal obtained for the Newton ring. From the result, we confirmed that the crack face contacting effect should be considered as a additive source of acoustic nonlinearity when we apply the ultrasonic nonlinearity analysis to the evaluation of material degradation.

  9. Ion Acoustic Waves in the Presence of Langmuir Oscillations

    Pécseli, Hans

    1976-01-01

    The dielectric function for long-wavelength, low-frequency ion acoustic waves in the presence of short-wavelength, high-frequency electron oscillations is presented, where the ions are described by the collision-free Vlasov equation. The effect of the electron oscillations can be appropriately de...

  10. Gasoline identifier based on SH0 plate acoustic waves.

    Kuznetsova, Iren E; Zaitsev, Boris D; Seleznev, Eugenii P; Verona, Enrico

    2016-08-01

    The present paper is devoted to the development of gasoline identifier based on zero order shear-horizontal (SH0) acoustic wave propagating in piezoelectric plate. It has been found that the permittivity of gasoline is increased when its octane number rises. The development of such identifier is experimentally demonstrated to be possible. PMID:27125559

  11. Standing surface acoustic wave (SSAW) based multichannel cell sorting

    Ding, Xiaoyun; Lin, Sz-Chin Steven; Lapsley, Michael Ian; Li, Sixing; Guo, Xiang; Chan, Chung Yu Keith; Chiang, I-Kao; Wang, Lin; McCoy, J. Philip; Huang, Tony Jun

    2012-01-01

    We introduce a novel microfluidic device for cell sorting in continuous flow using tunable standing surface acoustic waves. This method allows individual cells to be precisely directed into five different outlet channels in a single step. It is versatile, simple, label-free, non-invasive, and highly controllable.

  12. Enhancing Plasma Surface Modification using high Intensity and high Power Ultrasonic Acoustic Waves

    2010-01-01

    high intensity and high power acoustic waves (102) by at least one ultrasonic high intensity and high power acoustic wave generator (101 ), wherein the ultrasonic acoustic waves are directed to propagate towards said surface (314) of the object (100) so that a laminar boundary layer (313) of a gas or a...

  13. Subwavelength acoustic focusing by surface-wave-resonance enhanced transmission in doubly negative acoustic metamaterials

    We present analytical and numerical analyses of a yet unseen lensing paradigm that is based on a solid metamaterial slab in which the wave excitation source is attached. We propose and demonstrate sub-diffraction-limited acoustic focusing induced by surface resonant states in doubly negative metamaterials. The enhancement of evanescent waves across the metamaterial slab produced by their resonant coupling to surface waves is evidenced and quantitatively determined. The effect of metamaterial parameters on surface states, transmission, and wavenumber bandwidth is clearly identified. Based on this concept consisting of a wave source attached on the metamaterial, a high resolution of λ/28.4 is obtained with the optimum effective physical parameters, opening then an exciting way to design acoustic metamaterials for ultrasonic focused imaging

  14. Subwavelength acoustic focusing by surface-wave-resonance enhanced transmission in doubly negative acoustic metamaterials

    Zhou, Xiaoming; Badreddine Assouar, M., E-mail: Badreddine.Assouar@univ-lorraine.fr; Oudich, Mourad [CNRS, Institut Jean Lamour, Vandoeuvre-lès-Nancy F-54506 (France); Institut Jean Lamour, University of Lorraine, Boulevard des Aiguillettes, BP: 70239, 54506 Vandoeuvre-lès-Nancy (France)

    2014-11-21

    We present analytical and numerical analyses of a yet unseen lensing paradigm that is based on a solid metamaterial slab in which the wave excitation source is attached. We propose and demonstrate sub-diffraction-limited acoustic focusing induced by surface resonant states in doubly negative metamaterials. The enhancement of evanescent waves across the metamaterial slab produced by their resonant coupling to surface waves is evidenced and quantitatively determined. The effect of metamaterial parameters on surface states, transmission, and wavenumber bandwidth is clearly identified. Based on this concept consisting of a wave source attached on the metamaterial, a high resolution of λ/28.4 is obtained with the optimum effective physical parameters, opening then an exciting way to design acoustic metamaterials for ultrasonic focused imaging.

  15. Propagation-invariant waves in acoustic, optical, and radio-wave fields

    Salo, Janne

    2003-01-01

    The physical phenomena considered in this thesis are associated with electromagnetic and acoustic waves that propagate in free space or in homogeneous media without diffraction. The concept of rotationally periodic wave propagation is introduced in the first journal article included in the thesis and it is subsequently used to analyse waves that avoid diffractive deterioration by repeatedly returning to their initial shape, possibly rotated around the optical axis. Such waves constitute an es...

  16. Plasma-maser instability of the ion acoustics wave in the presence of lower hybrid wave turbulence in inhomogeneous plasma

    M Singh; P N Deka

    2006-03-01

    A theoretical study is made on the generation mechanism of ion acoustics wave in the presence of lower hybrid wave turbulence field in inhomogeneous plasma on the basis of plasma-maser interaction. The lower hybrid wave turbulence field is taken as the low-frequency turbulence field. The growth rate of test high frequency ion acoustics wave is obtained with the involvement of spatial density gradient parameter. A comparative study of the role of density gradient for the generation of ion acoustics wave on the basis of plasma-maser effect is presented. It is found that the density gradient influences the growth rate of ion acoustics wave.

  17. Controlling an acoustic wave with a cylindrically-symmetric gradient-index system

    We present a detailed theoretical description of wave propagation in an acoustic gradient-index system with cylindrical symmetry and demonstrate its potential to numerically control acoustic waves in different ways. The trajectory of an acoustic wave within the system is derived by employing the theory of geometric acoustics, and the validity of the theoretical descriptions is verified numerically by using the finite element method simulation. The results show that by tailoring the distribution function of the refractive index, the proposed system can yield a tunable manipulation of acoustic waves, such as acoustic bending, trapping, and absorbing. (paper)

  18. Synchronization of self-excited dust acoustic waves

    Suranga Ruhunusiri, W. D.; Goree, John

    2012-10-01

    Synchronization is a nonlinear phenomenon where a self-excited oscillation, like a wave in a plasma, interacts with an external driving, resulting in an adjustment of the oscillation frequency. Dust acoustic wave synchronization has been experimentally studied previously in laboratory and in microgravity conditions, e.g. [Pilch PoP 2009] and [Menzel PRL 2010]. We perform a laboratory experiment to study synchronization of self-excited dust acoustic waves. An rf glow discharge argon plasma is formed by applying a low power radio frequency voltage to a lower electrode. A 3D dust cloud is formed by levitating 4.83 micron microspheres inside a glass box placed on the lower electrode. Dust acoustic waves are self-excited with a natural frequency of 22 Hz due to an ion streaming instability. A cross section of the dust cloud is illuminated by a vertical laser sheet and imaged from the side with a digital camera. To synchronize the waves, we sinusoidally modulate the overall ion density. Differently from previous experiments, we use a driving electrode that is separate from the electrode that sustains the plasma, and we characterize synchronization by varying both driving amplitude and frequency.

  19. Chromospheric heating by acoustic waves compared to radiative cooling

    Sobotka, M; Švanda, M; Jurčák, J; del Moro, D; Berrilli, F

    2016-01-01

    Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of solar atmosphere. A weak chromospheric plage near a large solar pore NOAA 11005 was observed on October 15, 2008 in the lines Fe I 617.3 nm and Ca II 853.2 nm with the Interferometric Bidimemsional Spectrometer (IBIS) attached to the Dunn Solar Telescope. Analyzing the Ca II observations with spatial and temporal resolutions of 0.4" and 52 s, the energy deposited by acoustic waves is compared with that released by radiative losses. The deposited acoustic flux is estimated from power spectra of Doppler oscillations measured in the Ca II line core. The radiative losses are calculated using a grid of seven 1D hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of maps of radiative losses and acoustic flux is 72 %. In quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only of about 15 %. In active areas with photospheric ma...

  20. Modulational instability of ion acoustic waves in a magnetised plasma

    The modulational instability of ion acoustic waves is studied in the presence of d.c. magnetic field. It is found that while the instability sets in for wave numbers exceeding 1.47 ksub(D) in the absence of the magnetic field, the switching-on of the magnetic field can generate instability earlier. In general, two regions emerge where the waves can become modulationally unstable. The relative sizes of these regions change as the magnetic field and the angle of propagation are varied. (author)

  1. Langasite Surface Acoustic Wave Sensors: Fabrication and Testing

    Zheng, Peng; Greve, David W.; Oppenheim, Irving J.; Chin, Tao-Lun; Malone, Vanessa

    2012-02-01

    We report on the development of harsh-environment surface acoustic wave sensors for wired and wireless operation. Surface acoustic wave devices with an interdigitated transducer emitter and multiple reflectors were fabricated on langasite substrates. Both wired and wireless temperature sensing was demonstrated using radar-mode (pulse) detection. Temperature resolution of better than ±0.5°C was achieved between 200°C and 600°C. Oxygen sensing was achieved by depositing a layer of ZnO on the propagation path. Although the ZnO layer caused additional attenuation of the surface wave, oxygen sensing was accomplished at temperatures up to 700°C. The results indicate that langasite SAW devices are a potential solution for harsh-environment gas and temperature sensing.

  2. Optimization of Surface Acoustic Wave-Based Rate Sensors

    Fangqian Xu

    2015-10-01

    Full Text Available The optimization of an surface acoustic wave (SAW-based rate sensor incorporating metallic dot arrays was performed by using the approach of partial-wave analysis in layered media. The optimal sensor chip designs, including the material choice of piezoelectric crystals and metallic dots, dot thickness, and sensor operation frequency were determined theoretically. The theoretical predictions were confirmed experimentally by using the developed SAW sensor composed of differential delay line-oscillators and a metallic dot array deposited along the acoustic wave propagation path of the SAW delay lines. A significant improvement in sensor sensitivity was achieved in the case of 128° YX LiNbO3, and a thicker Au dot array, and low operation frequency were used to structure the sensor.

  3. Seismic wave imaging in visco-acoustic media

    WANG Huazhong; ZHANG Libin; MA Zaitian

    2004-01-01

    Realistic representation of the earth may be achieved by combining the mechanical properties of elastic solids and viscousliquids. That is to say, the amplitude will be attenuated withdifferent frequency and the phase will be changed in the seismicdata acquisition. In the seismic data processing, this effect mustbe compensated. In this paper, we put forward a visco-acoustic wavepropagator which is of better calculating stability and tolerablecalculating cost (little more than an acoustic wave propagator).The quite good compensation effect is demonstrated by thenumerical test results with synthetic seismic data and real data.

  4. High Frequency Acoustic Waves in the Sun's Atmosphere

    Fleck, B.; Jefferies, S. M.; McIntosh, S. W.; Severino, G.; Straus, T.; Tarbell, T. D.

    2008-09-01

    This year marks the 60th anniversary of two pioneering papers by Schwarzschild (1948) and Biermann (1948), who independently proposed that acoustic waves generated in the turbulent convection zone play an important role in the heating of the chromosphere and corona. High frequency acoustic waves have remained one of the leading contenders for solving the heating problem of the non-magnetic chromospheres of the Sun and late-type stars ever since. Earlier attempts to determine the acoustic energy flux from ground were compromised by atmospheric seeing, which has its biggest effect on the high frequency parts of the observed signal. Recently, based on a comparison of TRACE observations and 1-D simulations, Fossum & Carlsson (2005, 2006) concluded that high-frequency acoustic waves are not sufficient to heat the solar chromosphere. The same conclusion was reached by Carlsson et al. (2007) from an analysis of Hinode SOT/BFI Ca II H and blue continuum observations. Other authors (e.g. Cuntz et al. 2007; Wedemeyer-Boehm et al. 2007, Kalkofen 2007), however, questioned these results for a number of reasons. Because of its limited spatial resolution and limited sensitivity there are inherent difficulties when comparing TRACE observations with numerical simulations. Further, intensity oscillations are difficult to interpret, as they result from a phase-sensitive mix of temperature and pressure fluctuations, and non-local radiation transfer effects may complicate the picture even more. Here we revisit the role of high frequency acoustic waves in the dynamics and energetics of the Sun's atmosphere using high cadence, high resolution Doppler velocity measurements obtained with SOT/SP and SOT/NFI on Hinode.

  5. Numerics of surface acoustic wave (SAW) driven acoustic streaming and radiation force

    Nama, Nitesh; Barnkob, Rune; Kahler, Christian; Costanzo, Francesco; Jun Huang, Tony

    2015-11-01

    Recently, surface acoustic wave (SAW) based systems have shown great potential for various lab-on-a-chip applications. However, the physical understanding of the precise acoustic fields and associated acoustophoresis is rather limited. In this work, we present a numerical study of the acoustophoretic particle motion inside a SAW-actuated, liquid-filled polydimethylsiloxane (PDMS) microchannel. We utilize a perturbation approach to divide the flow variables into first- and second-order components. The first-order fields result in a time-averaged acoustic radiation force on suspended particles, as well as the time-averaged body force terms that drive the second-order fields. We model the SAW actuation by a displacement function while we utilize impedance boundary conditions to model the PDMS walls. We identify the precise acoustic fields generated inside the microchannel and investigate a range of particle sizes to characterize the transition from streaming-dominated acoustophoresis to radiation-force-dominated acoustophoresis. Lastly, we demonstrate the ability of SAW devices to tune the position of vertical pressure node inside the microchannel by tuning the phase difference between the two incoming surface acoustic waves.

  6. Tuneable film bulk acoustic wave resonators

    Gevorgian, Spartak Sh; Vorobiev, Andrei K

    2013-01-01

    To handle many standards and ever increasing bandwidth requirements, large number of filters and switches are used in transceivers of modern wireless communications systems. It makes the cost, performance, form factor, and power consumption of these systems, including cellular phones, critical issues. At present, the fixed frequency filter banks based on Film Bulk Acoustic Resonators (FBAR) are regarded as one of the most promising technologies to address performance -form factor-cost issues. Even though the FBARs improve the overall performances the complexity of these systems remains high.  Attempts are being made to exclude some of the filters by bringing the digital signal processing (including channel selection) as close to the antennas as possible. However handling the increased interference levels is unrealistic for low-cost battery operated radios. Replacing fixed frequency filter banks by one tuneable filter is the most desired and widely considered scenario. As an example, development of the softwa...

  7. Use of anisotropy to guide acoustic waves along desired trajectories

    Tehranian, Aref; Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2010-03-01

    Acoustic stress waves can be guided to follow pre-determined paths in solids, using elastic anisotropy. Recently, there has been intense interest to design materials and structures that can shield specific regions within the material by redirecting the incident stress-waves along desired paths. Some of the proposed techniques involve variable mass density and stiffness. We have designed a material with isotropic mass density but highly anisotropic elasticity that can guide incident waves along desired trajectories. Harmonic excitations are imposed, and it is shown that the stress-wave energy would travel around a protected central region. The model is also evaluated using numerical simulations, which confirm that majority of the stress-wave energy is guided around the central cavity and is delivered exactly to the opposing face in a location corresponding to the incident excitation location.

  8. Making structured metals transparent for ultrabroadband electromagnetic waves and acoustic waves

    In this review, we present our recent work on making structured metals transparent for broadband electromagnetic waves and acoustic waves via excitation of surface waves. First, we theoretically show that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic waves by relying on surface plasmons or spoof surface plasmons. Second, we experimentally demonstrate that metallic gratings with narrow slits are highly transparent for broadband terahertz waves at oblique incidence and high transmission efficiency is insensitive to the metal thickness. Further, we significantly develop oblique metal gratings transparent for broadband electromagnetic waves (including optical waves and terahertz ones) under normal incidence. In the third, we find the principles of broadband transparency for structured metals can be extended from one-dimensional metallic gratings to two-dimensional cases. Moreover, similar phenomena are found in sonic artificially metallic structures, which present the transparency for broadband acoustic waves. These investigations provide guidelines to develop many novel materials and devices, such as transparent conducting panels, antireflective solar cells, and other broadband metamaterials and stealth technologies. - Highlights: • Making structured metals transparent for ultrabroadband electromagnetic waves. • Non-resonant excitation of surface plasmons or spoof surface plasmons. • Sonic artificially metallic structures transparent for broadband acoustic waves

  9. Making structured metals transparent for ultrabroadband electromagnetic waves and acoustic waves

    Fan, Ren-Hao [National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Peng, Ru-Wen, E-mail: rwpeng@nju.edu.cn [National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Huang, Xian-Rong [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Wang, Mu [National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-07-15

    In this review, we present our recent work on making structured metals transparent for broadband electromagnetic waves and acoustic waves via excitation of surface waves. First, we theoretically show that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic waves by relying on surface plasmons or spoof surface plasmons. Second, we experimentally demonstrate that metallic gratings with narrow slits are highly transparent for broadband terahertz waves at oblique incidence and high transmission efficiency is insensitive to the metal thickness. Further, we significantly develop oblique metal gratings transparent for broadband electromagnetic waves (including optical waves and terahertz ones) under normal incidence. In the third, we find the principles of broadband transparency for structured metals can be extended from one-dimensional metallic gratings to two-dimensional cases. Moreover, similar phenomena are found in sonic artificially metallic structures, which present the transparency for broadband acoustic waves. These investigations provide guidelines to develop many novel materials and devices, such as transparent conducting panels, antireflective solar cells, and other broadband metamaterials and stealth technologies. - Highlights: • Making structured metals transparent for ultrabroadband electromagnetic waves. • Non-resonant excitation of surface plasmons or spoof surface plasmons. • Sonic artificially metallic structures transparent for broadband acoustic waves.

  10. SILICON COMPATIBLE ACOUSTIC WAVE RESONATORS: DESIGN, FABRICATION AND PERFORMANCE

    Aliza Aini Md Ralib

    2014-12-01

    Full Text Available ABSTRACT: Continuous advancement in wireless technology and silicon microfabrication has fueled exciting growth in wireless products. The bulky size of discrete vibrating mechanical devices such as quartz crystals and surface acoustic wave resonators impedes the ultimate miniaturization of single-chip transceivers. Fabrication of acoustic wave resonators on silicon allows complete integration of a resonator with its accompanying circuitry.  Integration leads to enhanced performance, better functionality with reduced cost at large volume production. This paper compiles the state-of-the-art technology of silicon compatible acoustic resonators, which can be integrated with interface circuitry. Typical acoustic wave resonators are surface acoustic wave (SAW and bulk acoustic wave (BAW resonators.  Performance of the resonator is measured in terms of quality factor, resonance frequency and insertion loss. Selection of appropriate piezoelectric material is significant to ensure sufficient electromechanical coupling coefficient is produced to reduce the insertion loss. The insulating passive SiO2 layer acts as a low loss material and aims to increase the quality factor and temperature stability of the design. The integration technique also is influenced by the fabrication process and packaging.  Packageless structure using AlN as the additional isolation layer is proposed to protect the SAW device from the environment for high reliability. Advancement in miniaturization technology of silicon compatible acoustic wave resonators to realize a single chip transceiver system is still needed. ABSTRAK: Kemajuan yang berterusan dalam teknologi tanpa wayar dan silikon telah menguatkan pertumbuhan yang menarik dalam produk tanpa wayar. Saiz yang besar bagi peralatan mekanikal bergetar seperti kristal kuarza menghalang pengecilan untuk merealisasikan peranti cip. Silikon serasi  gelombang akustik resonator mempunyai potensi yang besar untuk menggantikan unsur

  11. Optically tunable acoustic wave band-pass filter

    N. Swinteck

    2014-12-01

    Full Text Available The acoustic properties of a hybrid composite that exhibits both photonic and phononic behavior are investigated numerically with finite-element and finite-difference time-domain simulations. The structure is constituted of a periodic array of photonic resonant cavities embedded in a background superlattice. The resonant cavities contain a photo-elastic chalcogenide glass that undergoes atomic-scale structural reorganization when irradiated with light having energy close to its band-gap. Photo-excitation of the chalcogenide glass changes its elastic properties and, consequently, augments the acoustic transmission spectrum of the composite. By modulating the intensity of light irradiating the hybrid photonic/phononic structure, the position and spectral width of phonon passing-bands can be controlled. This demonstration offers the technological platform for optically-tunable acoustic wave band-pass filters.

  12. Superresolution through the topological shaping of sound with an acoustic vortex wave antenna

    Guild, Matthew D; Martin, Theodore P; Rohde, Charles A; Orris, Gregory J

    2016-01-01

    In this paper, we demonstrate far-field acoustic superresolution using shaped acoustic vortices. Compared with previously proposed near-field methods of acoustic superresolution, in this work we describe how far-field superresolution can be obtained using an acoustic vortex wave antenna. This is accomplished by leveraging the recent advances in optical vortices in conjunction with the topological diversity of a leaky wave antenna design. In particular, the use of an acoustic vortex wave antenna eliminates the need for a complicated phased array consisting of multiple active elements, and enables a superresolving aperture to be achieved with a single simple acoustic source and total aperture size less than a wavelength in diameter. A theoretical formulation is presented for the design of an acoustic vortex wave antenna with arbitrary planar arrangement, and explicit expressions are developed for the radiated acoustic pressure field. This geometric versatility enables variously-shaped acoustic vortex patterns t...

  13. Prospects for coupling Surface Acoustic Waves to superconducting qubits

    Gustafsson, Martin

    2013-03-01

    Recent years have seen great development in the quantum control of mechanical resonators. These usually consist of membranes, cantilevers or suspended beams, whose vibrational modes can be cooled to the quantum ground state. This presentation will focus on a different kind of micromechanical system, where the motion is not confined to a mode with fixed boundaries, but propagates along the surface of a microchip. These modes are known as Surface Acoustic Waves (SAWs), and superficially resemble ripples on water, moving with low loss along the surfaces of solids. On a piezoelectric substrate, electrode gratings known as Interdigital Transducers (IDTs) can be used to convert power between the electric and acoustic domains. Devices based on this effect are of profound technological importance as filters and analog signal processors in the RF domain. In the realm of quantum information processing, SAWs have primarily been used to transport carriers and excitons through piezoelectric semiconductors, in the electric potential wells propagating along with the mechanical wave. Our approach, however, is different in that we aim to explore the mechanical wave itself as a carrier of quantum information. We have previously shown that a single-electron transistor can be used as a local probe for SAWs, with encouraging sensitivity levels. Building on this, we now investigate the prospects for coupling a SAW beam directly to a superconducting qubit. By merging a circuit model for an IDT with a quasi-classical description of a transmon qubit, we estimate that the qubit can couple to an acoustic transmission line with approximately the same strength as to an electrical one. This type of coupling opens for acoustic analogs of recent experiments in microwave quantum optics, including the generation of non-classical acoustic states.

  14. A device for locating acoustic wave emitting sources

    The invention relates to a device for locating acoustic wave emitting sources. A two dimensional sensor network, with diamond-shaped (or the like) meshes, is placed on the surface of a structure in which acoustic wave emitting sources are to be located. The sensors are arranged according to two groups, each of which is connected to a clock and a counter. Every signal fed into a mesh of the network inhibits all the other sensors not belonging to said mesh; the location of the source within the diamond-shaped mesh is achieved by triangulation. This can be applied to the detection of flaws in metal structures, e.g. in nuclear reactor vessels

  15. Acoustic wave measurements in reactor-grade concretes

    In this paper, five reactor grade concretes were investigated during their initial cure period to gather information which is a suitable data base for interpreting the results of confirmatory reactor safety research programs. In particular, the concretes studied were the concrete proposed for the Clinch River Breeder Reactor (CRBR), which is a limestone mix with flyash, and two other limestone aggregate mixes and two basaltic-aggregate mixes. The curing process in these concretes was followed with strength tests and with acoustic-wave velocity measurements. The choice of the latter technique was based on the successful programs of several investigators who used acoustic waves to follow the curing process in concrete and this information was also required for instrumentation techniques that are proposed for accident simulation studies. (Auth.)

  16. HF Doppler observations of acoustic waves excited by the earthquake

    Ichinose, T.; Takagi, K.; Tanaka, T.; Okuzawa, T.; Shibata, T.; Sato, Y.; Nagasawa, C.; Ogawa, T.

    1985-01-01

    Ionospheric disturbances caused by the earthquake of a relatively small and large epicentral distance have been detected by a network of HF-Doppler sounders in central Japan and Kyoto station, respectively. The HF-Doppler data of a small epicentral distance, together with the seismic data, have been used to formulate a mechanism whereby ionospheric disturbances are produced by the Urakawa-Oki earthquake in Japan. Comparison of the dynamic spectra of these data has revealed experimentally that the atmosphere acts as a low-pass filter for upward-propagating acoustic waves. By surveying the earthquakes for which the magnitude M is larger than 6.0, researchers found the ionospheric effect in 16 cases of 82 seismic events. As almost all these effects have occurred in the daytime, it is considered that it may result from the filtering effect of the upward-propagating acoustic waves.

  17. Electron acoustic solitary waves with kappa-distributed electrons

    Devanandhan, S; Singh, S V; Lakhina, G S, E-mail: satyavir@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel (West), Navi Mumbai (India)

    2011-08-01

    Electron acoustic solitary waves are studied in a three-component, unmagnetized plasma composed of hot electrons, fluid cold electrons and ions having finite temperatures. Hot electrons are assumed to have kappa distribution. The Sagdeev pseudo-potential technique is used to study the arbitrary amplitude electron-acoustic solitary waves. It is found that inclusion of cold electron temperature shrinks the existence regime of the solitons, and soliton electric field amplitude decreases with an increase in cold electron temperature. A decrease in spectral index, {kappa}, i.e. an increase in the superthermal component of hot electrons, leads to a decrease in soliton electric field amplitude as well as the soliton velocity range. The soliton solutions do not exist beyond T{sub c}/T{sub h}>0.13 for {kappa}=3.0 and Mach number M=0.9 for the dayside auroral region parameters.

  18. A Statistical Study of Mid-latitude Thunderstorm Characteristics associated with Acoustic and Gravity Waves

    Lay, E. H.; Shao, X. M.; Kendrick, A.

    2014-12-01

    Gravity waves with periods greater than 5 minutes and acoustic waves with periods between 3 and 5 minutes have been detected at ionospheric heights (250-350 km) and associated with severe thunderstorms. Modeling results support these findings, indicating that acoustic waves should be able to reach 250-350 km within ~250 km horizontally of the source, and gravity waves should be able to propagate significantly further. However, the mechanism by which the acoustic waves are generated and the ubiquity of occurrence of both types of wave is unknown. We use GPS total electron content measurements to detect gravity and acoustic waves in the ionosphere. We perform a statistical study from 2005 May - July to compare the occurrence rate and horizontal extent of the waves to storm size and convective height from NEXRAD radar measurements. It is found that both gravity waves and acoustic wave horizontal extent is primarily associated with storm size and not convective height.

  19. Impact of Acoustic Standing Waves on Structural Responses

    Kolaini, Ali R.

    2014-01-01

    For several decades large reverberant chambers and most recently direct field acoustic testing have been used in the aerospace industry to test larger structures with low surface densities such as solar arrays and reflectors to qualify them and to detect faults in the design and fabrication. It has been reported that in reverberant chamber and direct acoustic testing, standing acoustic modes may strongly couple with the fundamental structural modes of the test hardware (Reference 1). In this paper results from a recent reverberant chamber acoustic test of a composite reflector are discussed. These results provide further convincing evidence of the acoustic standing wave and structural modes coupling phenomenon. The purpose of this paper is to alert test organizations to this phenomenon so that they can account for the potential increase in structural responses and ensure that flight hardware undergoes safe testing. An understanding of the coupling phenomenon may also help minimize the over and/or under testing that could pose un-anticipated structural and flight qualification issues.

  20. Acoustic Waves: A Route to Enhance Sodium Fast Reactor Safety

    The properties of sodium – both thermohydraulic and neutronic – offer a number of advantages when used as a coolant for fourth generation fast reactors. However, the opacity of sodium is a major drawback for the instrumentation. Acoustic waves could be an efficient means to sound this medium. An ultrasonic telemetry instrument called SONAR was used in the Phénix reactor to detect core movement, to check for missing objects and for sub-assembly handling. Acoustic methods were also used in Superphenix and considered for the EFR project as one of the monitoring solutions to detect anomalies. This paper focuses on the efforts made to develop acoustic techniques to meet the system protection and monitoring requirements. It covers various fields: the development of ultrasonic transducers such as the high-temperature ultrasonic transducer (TUSHT) which have recently been re-developed and manufactured, and current research on instrumentation methods using acoustic transducers for ASTRID. This paper discusses the development of acoustic-based instrument techniques as a means to strengthen the primary and secondary sodium system monitoring approach. In the case of TUSHTs, for example, the potential uses are: core monitoring during nominal operation, the detection of core meltdown accident initiators and fuel handling guidance. (author)

  1. High-Temperature Surface-Acoustic-Wave Transducer

    Zhao, Xiaoliang; Tittmann, Bernhard R.

    2010-01-01

    Aircraft-engine rotating equipment usually operates at high temperature and stress. Non-invasive inspection of microcracks in those components poses a challenge for the non-destructive evaluation community. A low-profile ultrasonic guided wave sensor can detect cracks in situ. The key feature of the sensor is that it should withstand high temperatures and excite strong surface wave energy to inspect surface/subsurface cracks. As far as the innovators know at the time of this reporting, there is no existing sensor that is mounted to the rotor disks for crack inspection; the most often used technology includes fluorescent penetrant inspection or eddy-current probes for disassembled part inspection. An efficient, high-temperature, low-profile surface acoustic wave transducer design has been identified and tested for nondestructive evaluation of structures or materials. The development is a Sol-Gel bismuth titanate-based surface-acoustic-wave (SAW) sensor that can generate efficient surface acoustic waves for crack inspection. The produced sensor is very thin (submillimeter), and can generate surface waves up to 540 C. Finite element analysis of the SAW transducer design was performed to predict the sensor behavior, and experimental studies confirmed the results. One major uniqueness of the Sol-Gel bismuth titanate SAW sensor is that it is easy to implement to structures of various shapes. With a spray coating process, the sensor can be applied to surfaces of large curvatures. Second, the sensor is very thin (as a coating) and has very minimal effect on airflow or rotating equipment imbalance. Third, it can withstand temperatures up to 530 C, which is very useful for engine applications where high temperature is an issue.

  2. Extremely Low-Loss Acoustic Phonons in a Quartz Bulk Acoustic Wave Resonator

    Goryachev, Maxim; Ivanov, Eugene N; Galliou, Serge; Bourquin, Roger; Tobar, Michael E

    2012-01-01

    Low-loss, high frequency acoustic resonators cooled to millikelvin temperatures are a topic of great interest for application to hybrid quantum systems. When cooled to 20 mK, we show that resonant acoustic phonon modes in a Bulk Acoustic Wave (BAW) quartz resonator demonstrate exceptionally low loss (with $Q$-factors of order billions) at frequencies of 15.6 and 65.4 MHz, with a maximum $f.Q$ product of 7.8$\\times10^{16}$ Hz. Given this result, we show that the $Q$-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained. Such resonators possess the low losses crucial for electromagnetic cooling to the phonon ground state, and the possibility of long coherence and interaction times of a few seconds, allowing multiple quantum gate operations.

  3. Ion acoustic waves in large radio-frequency electric fields

    The propagation of ion acoustic waves (IAW) in high-frequency fields is experimentally studied. The resulting phase-velocity shift and enhanced damping are observed for RF-field amplitudes up to α/sub e/ approximately equal to .5, where α/sub e/ = eE/(m/sub e/ω0v/sub e/) is the normalized amplitude. Good agreement with the theory of Albright is found. (auth)

  4. Surface acoustic wave applications of lithium niobate thin films

    A technique combining metalorganic decomposition and rf sputtering is used to grow lithium niobate (LiNbO3) thin films on diamond/silicon substrates, and surface acoustic wave (SAW) filters are fabricated by depositing interdigital transducers onto the multilayer LiNbO3/diamond/silicon structures. Microwave characterization is achieved by using a network analyzer. Evidence is found for SAW propagation in these structures. These experimental findings agree with theoretical predictions

  5. Surface acoustic wave probe implant for predicting epileptic seizures

    Gopalsami, Nachappa; Kulikov, Stanislav; Osorio, Ivan; Raptis, Apostolos C.

    2012-04-24

    A system and method for predicting and avoiding a seizure in a patient. The system and method includes use of an implanted surface acoustic wave probe and coupled RF antenna to monitor temperature of the patient's brain, critical changes in the temperature characteristic of a precursor to the seizure. The system can activate an implanted cooling unit which can avoid or minimize a seizure in the patient.

  6. Electron-acoustic plasma waves: oblique modulation and envelope solitons

    Kourakis, I.; Shukla, P. K.

    2004-01-01

    Theoretical and numerical studies are presented of the amplitude modulation of electron-acoustic waves (EAWs) propagating in space plasmas whose constituents are inertial cold electrons, Boltzmann distributed hot electrons and stationary ions. Perturbations oblique to the carrier EAW propagation direction have been considered. The stability analysis, based on a nonlinear Schroedinger equation (NLSE), reveals that the EAW may become unstable; the stability criteria depend on the angle $\\theta$...

  7. detection of buried objects using acoustic waves

    Many obstacles are faced in removing the buried landmines such as the loss or absence of maps or information about these mines and the high financial costs needed to remove these mines. So that many techniques were designed and developed for demining (detecting and clearing) these buried mines. Each technique has some strengths and drawbacks. This thesis presents a survey on the landmine detection techniques, the strengths and limitations of these techniques are highlighted and compared to show the ideal conditions and the challenges facing each technique. Furthermore, a comparison between these techniques from the points of view of cost, complexity, speed, safety, false alarms in detection and the effect of the environmental conditions is presented. one of the reliable and powerful landmine detection techniques is the Laser Doppler Vibrometer (LDV)-based Acoustic to Seismic (A/S) landmine detection system. The interpretation of the LDV-based A/S data is performed off-line manually, depending heavily on the skills, experience, alertness and consistency of a trained operator. This requires a significantly long time. Results typically suffer from inconsistency and errors, particularly when dealing with large volumes of data. This thesis proposes several image processing techniques to automate the process of landmine detection from the data scanned by the LDV-based A/S system. The obtained results are so far promising in terms of accuracy, consistency, reliability and processing speed. The previously proposed techniques for landmine detection give high false alarm rates. This thesis proposes some techniques to improve the performance of the automatic object detection techniques. These techniques are based on segmentation, masking, morphology image processing and the wavelet transform. These techniques have achieved a high detection rate.

  8. Numerical study of nonlinear full wave acoustic propagation

    Velasco-Segura, Roberto; Rendon, Pablo L.

    2013-11-01

    With the aim of describing nonlinear acoustic phenomena, a form of the conservation equations for fluid dynamics is presented, deduced using slightly less restrictive hypothesis than those necessary to obtain the well known Westervelt equation. This formulation accounts for full wave diffraction, nonlinearity, and thermoviscous dissipative effects. A CLAWPACK based, 2D finite-volume method using Roe's linearization has been implemented to obtain numerically the solution of the proposed equations. In order to validate the code, two different tests have been performed: one against a special Taylor shock-like analytic solution, the other against published results on a HIFU system, both with satisfactory results. The code is written for parallel execution on a GPU and improves performance by a factor of over 50 when compared to the standard CLAWPACK Fortran code. This code can be used to describe moderate nonlinear phenomena, at low Mach numbers, in domains as large as 100 wave lengths. Applications range from modest models of diagnostic and therapeutic HIFU, parametric acoustic arrays, to acoustic wave guides. A couple of examples will be presented showing shock formation and oblique interaction. DGAPA PAPIIT IN110411, PAEP UNAM 2013.

  9. Nonlinear progressive acoustic-gravity waves: Exact solutions

    Godin, Oleg

    2013-04-01

    We consider finite-amplitude mechanical waves in an inhomogeneous, compressible fluid in a uniform gravity field. The fluid is assumed to be inviscid, and wave motion is considered as an adiabatic thermodynamic process. The fluid either occupies an unbounded domain or has free and/or rigid boundaries. Wave motion is described by the momentum, continuity, and state equations in Lagrangian coordinates. We consider generic inhomogeneous fluids; no specific assumptions are made regarding the equation of state or spatial variations of the mass density or the sound speed in the absence of waves. The density and the sound speed are piece-wise continuous functions of position. The discontinuities represent fluid-fluid interfaces, such as the air-sea interface. Following a recent work on linear acoustic-gravity waves [O. A. Godin, Incompressible wave motion of compressible fluids, Phys. Rev. Lett., 108, 194501 (2012)], here we investigate a particular class of non-linear wave motions in fluids, in which pressure remains constant in each moving fluid parcel. Exact, analytic solutions of the non-linear hydrodynamics equations are obtained for two distinct scenarios. In the first scenario, the fluid is either unbounded or has a free surface. In the latter case, the exact analytic solution can be interpreted as a progressive surface wave. In the second scenario, the fluid has a free surface and a sloping, plane rigid boundary. Then the exact analytic solution represents an edge wave propagating horizontally along the rigid boundary. In both scenarios, the flow field associated with the finite-amplitude waves is rotational. When the sound speed tends to infinity, our results reduce to well-known finite-amplitude waves in incompressible fluids. In another limit, when the wave amplitude tends to zero, the exact solutions reduce to known results for linear waves in compressible fluids. The possibility of extending the theory to rotating fluids and fluids with a shearing background

  10. Characteristics of acoustic gravity waves obtained from Dynasonde data

    Negrea, Cǎtǎlin; Zabotin, Nikolay; Bullett, Terrence; Fuller-Rowell, Tim; Fang, Tzu-Wei; Codrescu, Mihail

    2016-04-01

    Traveling ionospheric disturbances (TIDs) are ubiquitous in the thermosphere-ionosphere and are often assumed to be caused by acoustic gravity waves (AGWs). This study performs an analysis of the TID and AGW activity above Wallops Island, VA, during October 2013. The variations in electron density and ionospheric tilts obtained with the Dynasonde technique are used as primary indicators of wave activity. The temporal and spectral characteristics of the data are discussed in detail, using also results of the Whole Atmosphere Model (WAM) and the Global Ionosphere Plasmasphere Model (GIP). The full set of propagation parameters (frequency, and the vertical, zonal and meridional wave vector components) of the TIDs is determined over the 160-220 km height range. A test of the self-consistency of these results within the confines of the theoretical AGW dispersion relation is devised. This is applied to a sample data set of 24 October 2013. A remarkable agreement has been achieved for wave periods between 52 and 21 min, for which we can rigorously claim the TIDs are caused by underlying acoustic gravity waves. The Wallops Island Dynasonde can operate for extended periods at a 2 min cadence, allowing determination of the statistical distributions of propagation parameters. A dominant population of TIDs is identified in the frequency band below 1 mHz, and for it, the distributions of the horizontal wavelengths, vertical wavelengths, and horizontal phase speeds are obtained.

  11. Ion acoustic shock wave in collisional equal mass plasma

    Adak, Ashish, E-mail: ashish-adak@yahoo.com [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Ghosh, Samiran, E-mail: sran-g@yahoo.com [Department of Applied Mathematics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700 064 (India)

    2015-10-15

    The effect of ion-ion collision on the dynamics of nonlinear ion acoustic wave in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear wave, the viscosity mediates wave dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the shock structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear wave is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic wave exhibits both oscillatory and monotonic shock structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments.

  12. Dual mode acoustic wave sensor for precise pressure reading

    Mu, Xiaojing; Kropelnicki, Piotr; Wang, Yong; Randles, Andrew Benson; Chuan Chai, Kevin Tshun; Cai, Hong; Gu, Yuan Dong

    2014-09-01

    In this letter, a Microelectromechanical system acoustic wave sensor, which has a dual mode (lateral field exited Lamb wave mode and surface acoustic wave (SAW) mode) behavior, is presented for precious pressure change read out. Comb-like interdigital structured electrodes on top of piezoelectric material aluminium nitride (AlN) are used to generate the wave modes. The sensor membrane consists of single crystalline silicon formed by backside-etching of the bulk material of a silicon on insulator wafer having variable device thickness layer (5 μm-50 μm). With this principle, a pressure sensor has been fabricated and mounted on a pressure test package with pressure applied to the backside of the membrane within a range of 0 psi to 300 psi. The temperature coefficient of frequency was experimentally measured in the temperature range of -50 °C to 300 °C. This idea demonstrates a piezoelectric based sensor having two modes SAW/Lamb wave for direct physical parameter—pressure readout and temperature cancellation which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications using the dual mode behavior of the sensor and differential readout at the same time.

  13. Ion acoustic shock wave in collisional equal mass plasma

    The effect of ion-ion collision on the dynamics of nonlinear ion acoustic wave in an unmagnetized pair-ion plasma has been investigated. The two-fluid model has been used to describe the dynamics of both positive and negative ions with equal masses. It is well known that in the dynamics of the weakly nonlinear wave, the viscosity mediates wave dissipation in presence of weak nonlinearity and dispersion. This dissipation is responsible for the shock structures in pair-ion plasma. Here, it has been shown that the ion-ion collision in presence of collective phenomena mediated by the plasma current is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The dynamics of the weakly nonlinear wave is governed by the Korteweg-de Vries Burgers equation. The analytical and numerical investigations revealed that the ion acoustic wave exhibits both oscillatory and monotonic shock structures depending on the frequency of ion-ion collision parameter. The results have been discussed in the context of the fullerene pair-ion plasma experiments

  14. Dust-acoustic rogue waves in a nonextensive plasma.

    Moslem, W M; Sabry, R; El-Labany, S K; Shukla, P K

    2011-12-01

    We present an investigation for the generation of a dust-acoustic rogue wave in a dusty plasma composed of negatively charged dust grains, as well as nonextensive electrons and ions. For this purpose, the reductive perturbation technique is used to obtain a nonlinear Schrödinger equation. The critical wave-number threshold k(c), which indicates where the modulational instability sets in, has been determined precisely for various regimes. Two different behaviors of k(c) against the nonextensive parameter q are found. For small k(c), it is found that increasing q would lead to an increase of k(c) until q approaches a certain value q(c), then further increase of q beyond q(c) decreases the value of k(c). For large k(c), the critical wave-number threshold k(c) is always increasing with q. Within the modulational instability region, a random perturbation of the amplitude grows and thus creates dust-acoustic rogue waves. In order to show that the characteristics of the rogue waves are influenced by the plasma parameters, the relevant numerical analysis of the appropriate nonlinear solution is presented. The nonlinear structure, as reported here, could be useful for controlling and maximizing highly energetic pulses in dusty plasmas. PMID:22304203

  15. Influence of surface acoustic waves induced acoustic streaming on the kinetics of electrochemical reactions

    Tietze, Sabrina; Schlemmer, Josefine; Lindner, Gerhard

    2013-12-01

    The kinetics of electrochemical reactions is controlled by diffusion processes of charge carriers across a boundary layer between the electrode and the electrolyte, which result in a shielding of the electric field inside the electrolyte and a concentration gradient across this boundary layer. In accumulators the diffusion rate determines the rather long time needed for charging, which is a major drawback for electric mobility. This diffusion boundary can be removed by acoustic streaming in the electrolyte induced by surface acoustic waves propagating of the electrode, which results in an increase of the charging current and thus in a reduction of the time needed for charging. For a quantitative study of the influence of acoustic streaming on the charge transport an electropolishing cell with vertically oriented copper electrodes and diluted H3PO4-Propanol electrolytes were used. Lamb waves with various excitation frequencies were exited on the anode with different piezoelectric transducers, which induced acoustic streaming in the overlaying electrolytic liquid. An increase of the polishing current of up to approximately 100 % has been obtained with such a set-up.

  16. Guided wave opto-acoustic device

    Jarecki, Jr., Robert L.; Rakich, Peter Thomas; Camacho, Ryan; Shin, Heedeuk; Cox, Jonathan Albert; Qiu, Wenjun; Wang, Zheng

    2016-02-23

    The various technologies presented herein relate to various hybrid phononic-photonic waveguide structures that can exhibit nonlinear behavior associated with traveling-wave forward stimulated Brillouin scattering (forward-SBS). The various structures can simultaneously guide photons and phonons in a suspended membrane. By utilizing a suspended membrane, a substrate pathway can be eliminated for loss of phonons that suppresses SBS in conventional silicon-on-insulator (SOI) waveguides. Consequently, forward-SBS nonlinear susceptibilities are achievable at about 3000 times greater than achievable with a conventional waveguide system. Owing to the strong phonon-photon coupling achievable with the various embodiments, potential application for the various embodiments presented herein cover a range of radiofrequency (RF) and photonic signal processing applications. Further, the various embodiments presented herein are applicable to applications operating over a wide bandwidth, e.g. 100 MHz to 50 GHz or more.

  17. Ion acoustic and dust acoustic waves at finite size of plasma particles

    We consider the influence of the finite size of ions on the properties of classic plasmas. We focus our attention at the ion acoustic waves for electron-ion plasmas. We also consider the dusty plasmas where we account the finite size of ions and particles of dust and consider the dispersion of dust acoustic waves. The finite size of particles is a classical effect as well as the Coulomb interaction. The finite size of particles considerably contributes to the properties of the dense plasmas in the small wavelength limit. Low temperature dense plasmas, revealing the quantum effects, are also affected by the finite size of plasma particles. Consequently, it is important to consider the finite size of ions in the quantum plasmas as well

  18. Acoustic tests of Lorentz symmetry using Bulk Acoustic Wave quartz oscillators

    Goryachev, M; Haslinger, Ph; Mizrachi, E; Anderegg, L; Müller, H; Hohensee, M; Tobar, M E

    2016-01-01

    A new method of probing Lorentz invariance in the neutron sector is described. The method is baed on stable quartz bulk acoustic wave oscillators compared on a rotating table. Due to Lorentz-invariance violation, the resonance frequencies of acoustic wave resonators depend on the direction in space via a corresponding dependence of masses of the constituent elements of solids. This dependence is measured via observation of oscillator phase noise built around such devices. The first such experiment now shows sensitivity to violation down to the limit $\\tilde{c}^n_Q=(-1.8\\pm2.2)\\times 10^{-14}$ GeV. Methods to improve the sensitivity are described together with some other applications of the technology in tests of fundamental physics.

  19. Single-electron transport driven by surface acoustic waves: Moving quantum dots versus short barriers

    Utko, Pawel; Hansen, Jørn Bindslev; Lindelof, Poul Erik;

    2007-01-01

    We have investigated the response of the acoustoelectric-current driven by a surface-acoustic wave through a quantum point contact in the closed-channel regime. Under proper conditions, the current develops plateaus at integer multiples of ef when the frequency f of the surface-acoustic wave or the...... gate voltage V-g of the point contact is varied. A pronounced 1.1 MHz beat period of the current indicates that the interference of the surface-acoustic wave with reflected waves matters. This is supported by the results obtained after a second independent beam of surface-acoustic wave was added...

  20. Ultrafast strain gauge: Observation of THz radiation coherently generated by acoustic waves

    The study of nanoscale, terahertz frequency (THz) acoustic waves has great potential for elucidating material and chemical interactions as well as nanostructure characterization. Here we report the first observation of terahertz radiation coherently generated by an acoustic wave. Such emission is directly related to the time-dependence of the stress as the acoustic wave crosses an interface between materials of differing piezoelectric response. This phenomenon enables a new class of strain wave metrology that is fundamentally distinct from optical approaches, providing passive remote sensing of the dynamics of acoustic waves with ultrafast time resolution. The new mechanism presented here enables nanostructure measurements not possible using existing optical or x-ray approaches

  1. Flow velocity measurement with the nonlinear acoustic wave scattering

    A problem of noninvasive measurement of liquid flow velocity arises in many practical applications. To this end the most often approach is the use of the linear Doppler technique. The Doppler frequency shift of signal scattered from the inhomogeneities distributed in a liquid relatively to the emitted frequency is proportional to the sound frequency and velocities of inhomogeneities. In the case of very slow flow one needs to use very high frequency sound. This approach fails in media with strong sound attenuation because acoustic wave attenuation increases with frequency and there is limit in increasing sound intensity, i.e. the cavitation threshold. Another approach which is considered in this paper is based on the method using the difference frequency Doppler Effect for flows with bubbles. This method is based on simultaneous action of two high-frequency primary acoustic waves with closed frequencies on bubbles and registration of the scattered by bubbles acoustic field at the difference frequency. The use of this method is interesting since the scattered difference frequency wave has much lower attenuation in a liquid. The theoretical consideration of the method is given in the paper. The experimental examples confirming the theoretical equations, as well as the ability of the method to be applied in medical diagnostics and in technical applications on measurement of flow velocities in liquids with strong sound attenuation is described. It is shown that the Doppler spectrum form depends on bubble concentration velocity distribution in the primary acoustic beams crossing zone that allows one to measure the flow velocity distribution

  2. Flow velocity measurement with the nonlinear acoustic wave scattering

    Didenkulov, Igor, E-mail: din@appl.sci-nnov.ru [Institute of Applied Physics, 46 Ulyanov str., Nizhny Novgorod, 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin ave., Nizhny Novgorod, 603950 (Russian Federation); Pronchatov-Rubtsov, Nikolay, E-mail: nikvas@rf.unn.ru [Lobachevsky State University of Nizhny Novgorod, 23 Gagarin ave., Nizhny Novgorod, 603950 (Russian Federation)

    2015-10-28

    A problem of noninvasive measurement of liquid flow velocity arises in many practical applications. To this end the most often approach is the use of the linear Doppler technique. The Doppler frequency shift of signal scattered from the inhomogeneities distributed in a liquid relatively to the emitted frequency is proportional to the sound frequency and velocities of inhomogeneities. In the case of very slow flow one needs to use very high frequency sound. This approach fails in media with strong sound attenuation because acoustic wave attenuation increases with frequency and there is limit in increasing sound intensity, i.e. the cavitation threshold. Another approach which is considered in this paper is based on the method using the difference frequency Doppler Effect for flows with bubbles. This method is based on simultaneous action of two high-frequency primary acoustic waves with closed frequencies on bubbles and registration of the scattered by bubbles acoustic field at the difference frequency. The use of this method is interesting since the scattered difference frequency wave has much lower attenuation in a liquid. The theoretical consideration of the method is given in the paper. The experimental examples confirming the theoretical equations, as well as the ability of the method to be applied in medical diagnostics and in technical applications on measurement of flow velocities in liquids with strong sound attenuation is described. It is shown that the Doppler spectrum form depends on bubble concentration velocity distribution in the primary acoustic beams crossing zone that allows one to measure the flow velocity distribution.

  3. Flow velocity measurement with the nonlinear acoustic wave scattering

    Didenkulov, Igor; Pronchatov-Rubtsov, Nikolay

    2015-10-01

    A problem of noninvasive measurement of liquid flow velocity arises in many practical applications. To this end the most often approach is the use of the linear Doppler technique. The Doppler frequency shift of signal scattered from the inhomogeneities distributed in a liquid relatively to the emitted frequency is proportional to the sound frequency and velocities of inhomogeneities. In the case of very slow flow one needs to use very high frequency sound. This approach fails in media with strong sound attenuation because acoustic wave attenuation increases with frequency and there is limit in increasing sound intensity, i.e. the cavitation threshold. Another approach which is considered in this paper is based on the method using the difference frequency Doppler Effect for flows with bubbles. This method is based on simultaneous action of two high-frequency primary acoustic waves with closed frequencies on bubbles and registration of the scattered by bubbles acoustic field at the difference frequency. The use of this method is interesting since the scattered difference frequency wave has much lower attenuation in a liquid. The theoretical consideration of the method is given in the paper. The experimental examples confirming the theoretical equations, as well as the ability of the method to be applied in medical diagnostics and in technical applications on measurement of flow velocities in liquids with strong sound attenuation is described. It is shown that the Doppler spectrum form depends on bubble concentration velocity distribution in the primary acoustic beams crossing zone that allows one to measure the flow velocity distribution.

  4. Synchronization of the dust acoustic wave under microgravity

    Ruhunusiri, W. D. Suranga; Goree, J.

    2013-10-01

    Synchronization is a nonlinear phenomenon where a self-excited oscillation, like a wave in a plasma, interacts with an external driving, resulting in an adjustment of the oscillation frequency. To prepare for experiments under microgravity conditions using the PK-4 facility on the International Space Station, we perform a laboratory experiment to observe synchronization of the self-excited dust acoustic wave. An rf glow discharge argon plasma is formed by applying a low power radio frequency voltage to a lower electrode. A 3D dust cloud is formed by levitating 4.83 micron microspheres inside a glass box placed on the lower electrode. The dust acoustic wave is self-excited with a natural frequency of 22 Hz due to an ion streaming instability. A cross section of the dust cloud is illuminated by a vertical laser sheet and imaged from the side with a digital camera. To synchronize the wave, we sinusoidally modulate the overall ion density. Differently from previous experiments, we use a driving electrode that is separate from the electrode that sustains the plasma, and we characterize synchronization by varying both driving amplitude and frequency. Supported by NASA's Physical Science Research Program.

  5. Overstability of acoustic waves in strongly magnetized anisotropic MHD shear flows

    Uchava, E S; Tevzadze, A G; Poedts, S

    2014-01-01

    We present a linear stability analysis of the perturbation modes in anisotropic MHD flows with velocity shear and strong magnetic field. Collisionless or weakly collisional plasma is described within the 16-momentum MHD fluid closure model, that takes into account not only the effect of pressure anisotropy, but also the effect of anisotropic heat fluxes. In this model the low frequency acoustic wave is revealed into a standard acoustic mode and higher frequency fast thermo-acoustic and lower frequency slow thermo-acoustic waves. It is shown that thermo-acoustic waves become unstable and grow exponentially when the heat flux parameter exceeds some critical value. It seems that velocity shear makes thermo-acoustic waves overstable even at subcritical heat flux parameters. Thus, when the effect of heat fluxes is not profound acoustic waves will grow due to the velocity shear, while at supercritical heat fluxes the flow reveals compressible thermal instability. Anisotropic thermal instability should be also impor...

  6. Determination of hydrocarbon levels in water via laser-induced acoustics wave

    Bidin, Noriah; Hossenian, Raheleh; Duralim, Maisarah; Krishnan, Ganesan; Marsin, Faridah Mohd; Nughro, Waskito; Zainal, Jasman

    2016-04-01

    Hydrocarbon contamination in water is a major environmental concern in terms of foreseen collapse of the natural ecosystem. Hydrocarbon level in water was determined by generating acoustic wave via an innovative laser-induced breakdown in conjunction with high-speed photographic coupling with piezoelectric transducer to trace acoustic wave propagation. A Q-switched Nd:YAG (40 mJ) was focused in cuvette-filled hydrocarbon solution at various concentrations (0-2000 ppm) to induce optical breakdown, shock wave generation and later acoustic wave propagation. A nitro-dye (ND) laser (10 mJ) was used as a flash to illuminate and frozen the acoustic wave propagation. Lasers were synchronised using a digital delay generator. The image of acoustic waves was grabbed and recorded via charged couple device (CCD) video camera at the speed of 30 frames/second with the aid of Matrox software version 9. The optical delay (0.8-10.0 μs) between the acoustic wave formation and its frozen time is recorded through photodetectors. A piezo-electric transducer (PZT) was used to trace the acoustic wave (sound signal), which cascades to a digital oscilloscope. The acoustic speed is calculated from the ratio of acoustic wave radius (1-8 mm) and optical time delay. Acoustic wave speed is found to linearly increase with hydrocarbon concentrations. The acoustic signal generation at higher hydrocarbon levels in water is attributed to supplementary mass transfer and impact on the probe. Integrated high-speed photography with transducer detection system authenticated that the signals indeed emerged from the laser-induced acoustic wave instead of photothermal processes. It is established that the acoustic wave speed in water is used as a fingerprint to detect the hydrocarbon levels.

  7. Surface Modification on Acoustic Wave Biosensors for Enhanced Specificity

    Nathan D. Gallant

    2012-09-01

    Full Text Available Changes in mass loading on the surface of acoustic biosensors result in output frequency shifts which provide precise measurements of analytes. Therefore, to detect a particular biomarker, the sensor delay path must be judiciously designed to maximize sensitivity and specificity. B-cell lymphoma 2 protein (Bcl-2 found in urine is under investigation as a biomarker for non-invasive early detection of ovarian cancer. In this study, surface chemistry and biofunctionalization approaches were evaluated for their effectiveness in presenting antibodies for Bcl-2 capture while minimizing non-specific protein adsorption. The optimal combination of sequentially adsorbing protein A/G, anti-Bcl-2 IgG and Pluronic F127 onto a hydrophobic surface provided the greatest signal-to-noise ratio and enabled the reliable detection of Bcl-2 concentrations below that previously identified for early stage ovarian cancer as characterized by a modified ELISA method. Finally, the optimal surface modification was applied to a prototype acoustic device and the frequency shift for a range of Bcl-2 concentration was quantified to demonstrate the effectiveness in surface acoustic wave (SAW-based detection applications. The surface functionalization approaches demonstrated here to specifically and sensitively detect Bcl-2 in a working ultrasonic MEMS biosensor prototype can easily be modified to detect additional biomarkers and enhance other acoustic biosensors.

  8. Longitudinal elastic wave propagation characteristics of inertant acoustic metamaterials

    Kulkarni, Prateek P.; Manimala, James M.

    2016-06-01

    Longitudinal elastic wave propagation characteristics of acoustic metamaterials with various inerter configurations are investigated using their representative one-dimensional discrete element lattice models. Inerters are dynamic mass-amplifying mechanical elements that are activated by a difference in acceleration across them. They have a small device mass but can provide a relatively large dynamic mass presence depending on accelerations in systems that employ them. The effect of introducing inerters both in local attachments and in the lattice was examined vis-à-vis the propagation characteristics of locally resonant acoustic metamaterials. A simple effective model based on mass, stiffness, or their combined equivalent was used to establish dispersion behavior and quantify attenuation within bandgaps. Depending on inerter configurations in local attachments or in the lattice, both up-shift and down-shift in the bandgap frequency range and their extent are shown to be possible while retaining static mass addition to the host structure to a minimum. Further, frequency-dependent negative and even extreme effective-stiffness regimes are encountered. The feasibility of employing tuned combinations of such mass-delimited inertant configurations to engineer acoustic metamaterials that act as high-pass filters without the use of grounded elements or even as complete longitudinal wave inhibitors is shown. Potential device implications and strategies for practical applications are also discussed.

  9. Energy Trapping in Low Phase Noise Bulk Acoustic Wave Oscillators

    In the design of resonators in low phase noise bulk acoustic wave (BAW) oscillators, maximization of quality factor is the primary target while energy trapping is not typically of concern. Analysis shows that although energy-trapping mode energy outside the electroded region decreases exponentially with distance away from the electrode edge of the wafer, the decaying wave will reflect at the wafer edge to the electroded region and generate a wave with same frequency but different phase which generates mutual modulation with resonant frequency. It is a source of phase noise and mainly affects the near-carrier-frequency phase noise. Two 120 MHz SC-cut 5th overtone UM-1 crystals with similar dynamic equivalent parameters and different shunt capacitances are compared using the same circuit. Experimental results show that energy trapping also needs to be considered in the design of resonators in low phase noise BAW oscillators

  10. Langasite Surface Acoustic Wave Gas Sensors: Modeling and Verification

    Zheng, Peng; Greve, David W; Oppenheim, Irving J

    2013-01-01

    We report finite element simulations of the effect of conductive sensing layers on the surface wave velocity of langasite substrates. The simulations include both the mechanical and electrical influences of the conducting sensing layer. We show that three-dimensional simulations are necessary because of the out-of-plane displacements of the commonly used (0, 138.5, 26.7) Euler angle. Measurements of the transducer input admittance in reflective delay-line devices yield a value for the electromechanical coupling coefficient that is in good agreement with the three-dimensional simulations on bare langasite substrate. The input admittance measurements also show evidence of excitation of an additional wave mode and excess loss due to the finger resistance. The results of these simulations and measurements will be useful in the design of surface acoustic wave gas sensors.

  11. Nonlinear acoustic waves in a collisional self-gravitating dusty plasma

    Guo Zhi-Rong; Yang Zeng-Qiang; Yin Bao-Xiang; Sun Mao-Zhu

    2010-01-01

    Using the reductive perturbation method,we investigate the small amplitude nonlinear acoustic wave in a collisional self-gravitating dusty plasma.The result shows that the small amplitude dust acoustic wave can be expressed by a modified Korteweg-de Vries equation,and the nonlinear wave is instable because of the collisions between the neutral gas molecules and the charged particles.

  12. Underwater acoustic wave generation by filamentation of terawatt ultrashort laser pulses

    Jukna, Vytautas; Milián, Carles; Brelet, Yohann; Carbonnel, Jérôme; André, Yves-Bernard; Guillermin, Régine; Sessarego, Jean-Pierre; Fattaccioli, Dominique; Mysyrowicz, André; Couairon, Arnaud; Houard, Aurélien

    2016-01-01

    Acoustic signals generated by filamentation of ultrashort TW laser pulses in water are characterized experimentally. Measurements reveal a strong influence of input pulse duration on the shape and intensity of the acoustic wave. Numerical simulations of the laser pulse nonlinear propagation and the subsequent water hydrodynamics and acoustic wave generation show that the strong acoustic emission is related to the mechanism of superfilamention in water. The elongated shape of the plasma volume where energy is deposited drives the far-field profile of the acoustic signal, which takes the form of a radially directed pressure wave with a single oscillation and a very broad spectrum.

  13. THE INFLUENCE OF WAVE PATTERNS AND FREQUENCY ON THERMO-ACOUSTIC COOLING EFFECT

    CHEN BAIMAN

    2011-06-01

    Full Text Available With the increasing environmental challenges, the search for an environmentally benign cooling technology that has simple and robust architecture continues. Thermo-acoustic refrigeration seems to be a promising candidate to fulfil these requirements. In this study, a simple thermo-acoustic refrigeration system was fabricated and tested. The thermo-acoustic refrigerator consists of acoustic driver (loudspeaker, resonator, stack, vacuum system and testing system. The effect of wave patterns and frequency on thermo-acoustic cooling effect was studied. It was found that a square wave pattern would yield superior cooling effects compared to other wave patterns tested.

  14. Visualization of Surface Acoustic Waves in Thin Liquid Films.

    Rambach, R W; Taiber, J; Scheck, C M L; Meyer, C; Reboud, J; Cooper, J M; Franke, T

    2016-01-01

    We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect. PMID:26917490

  15. Focusing of Surface Acoustic Wave on a Piezoelectric Crystal

    QIAO Dong-Hai; WANG Cheng-Hao; WANG Zuo-Qing

    2006-01-01

    @@ We investigate the focusing phenomena of a surface acoustic wave (SAW) field generated by a circular-arc interdigital transducer (IDT) on a piezoelectric crystal. A rigorous vector field theory of surface excitation on the crystal we developed previously is used to evaluate the convergent SAW field instead of the prevalent scalar angular spectrum used in optics. The theoretical results show that the anisotropy of a medium has great impact on the focusing properties of the acoustic beams, such as focal length and symmetrical distributions near the focus. A dark field method is used in experiment to observe the focusing of the SAW field optically. Although the convergent phenomena of SAW field on the anisotropic media or piezoelectric crystals are very complicated,the experimental data are in agreement with those from the rigorous theory.

  16. Visualization of Surface Acoustic Waves in Thin Liquid Films

    Rambach, R. W.; Taiber, J.; Scheck, C. M. L.; Meyer, C.; Reboud, J.; Cooper, J. M.; Franke, T.

    2016-01-01

    We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect. PMID:26917490

  17. Modulational instability of ion-acoustic waves in a warm plasma

    薛具奎; 段文山; 郎和

    2002-01-01

    Using the standard reductive perturbation technique, a nonlinear Schrodinger equation is derived to study themodulational instability of finite-amplitude ion-acoustic waves in a non-magnetized warm plasma. It is found thatthe inclusion of ion temperature in the equation modifies the nature of the ion-acoustic wave stability and the solitonstructures. The effects of ion plasma temperature on the modulational stability and ion-acoustic wave properties areinvestigated in detail.

  18. Molding acoustic, electromagnetic and water waves with a single cloak

    Xu, Jun

    2015-06-09

    We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. © 2015, Nature Publishing Group. All rights reserved.

  19. Molding acoustic, electromagnetic and water waves with a single cloak.

    Xu, Jun; Jiang, Xu; Fang, Nicholas; Georget, Elodie; Abdeddaim, Redha; Geffrin, Jean-Michel; Farhat, Mohamed; Sabouroux, Pierre; Enoch, Stefan; Guenneau, Sébastien

    2015-01-01

    We describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves. PMID:26057934

  20. System and method for sonic wave measurements using an acoustic beam source

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2015-08-11

    A method and system for investigating structure near a borehole are described herein. The method includes generating an acoustic beam by an acoustic source; directing at one or more azimuthal angles the acoustic beam towards a selected location in a vicinity of a borehole; receiving at one or more receivers an acoustic signal, the acoustic signal originating from a reflection or a refraction of the acoustic wave by a material at the selected location; and analyzing the received acoustic signal to characterize features of the material around the borehole.

  1. Passive Wireless Hydrogen Sensors Using Orthogonal Frequency Coded Acoustic Wave Devices Project

    National Aeronautics and Space Administration — This proposal describes the development of passive surface acoustic wave (SAW) based hydrogen sensors for NASA application to distributed wireless hydrogen leak...

  2. Passive Wireless Cryogenic Liquid Level Sensors Using Orthogonal Frequency Coded Acoustic Wave Devices Project

    National Aeronautics and Space Administration — This proposal describes the continued development of passive wireless surface acoustic wave (SAW) based liquid level sensors for NASA application to cryogenic...

  3. Numerical and experimental study of Lamb wave propagation in a two-dimensional acoustic black hole

    Yan, Shiling; Lomonosov, Alexey M.; Shen, Zhonghua

    2016-06-01

    The propagation of laser-generated Lamb waves in a two-dimensional acoustic black-hole structure was studied numerically and experimentally. The geometrical acoustic theory has been applied to calculate the beam trajectories in the region of the acoustic black hole. The finite element method was also used to study the time evolution of propagating waves. An optical system based on the laser-Doppler vibration method was assembled. The effect of the focusing wave and the reduction in wave speed of the acoustic black hole has been validated.

  4. Passive Wireless Hydrogen Sensors Using Orthogonal Frequency Coded Acoustic Wave Devices Project

    National Aeronautics and Space Administration — This proposal describes the continued development of passive orthogonal frequency coded (OFC) surface acoustic wave (SAW) based hydrogen sensors for NASA...

  5. Experimental quiescent drifting dusty plasmas and temporal dust acoustic wave growth

    We report on dust acoustic wave growth rate measurements taken in a dc (anode glow) discharge plasma device. By introducing a mesh with a variable bias 12-17 cm from the anode, we developed a technique to produce a drifting dusty plasma. A secondary dust cloud, free of dust acoustic waves, was trapped adjacent to the anode side of the mesh. When the mesh was returned to its floating potential, the secondary cloud was released and streamed towards the anode and primary dust cloud, spontaneously exciting dust acoustic waves. The amplitude growth of the excited dust acoustic waves was measured directly along with the wavelength and Doppler shifted frequency. These measurements were compared to fluid and kinetic dust acoustic wave theories. As the wave growth saturated a transition from linear to nonlinear waves was observed. The merging of the secondary and primary dust clouds was also observed.

  6. GPS-Acoustic Seafloor Geodesy using a Wave Glider

    Chadwell, C. D.

    2013-12-01

    The conventional approach to implement the GPS-Acoustic technique uses a ship or buoy for the interface between GPS and Acoustics. The high cost and limited availability of ships restricts occupations to infrequent campaign-style measurements. A new approach to address this problem uses a remote controlled, wave-powered sea surface vehicle, the Wave Glider. The Wave Glider uses sea-surface wave action for forward propulsion with both upward and downward motions producing forward thrust. It uses solar energy for power with solar panels charging the onboard 660 W-h battery for near continuous operation. It uses Iridium for communication providing command and control from shore plus status and user data via the satellite link. Given both the sea-surface wave action and solar energy are renewable, the vehicle can operate for extended periods (months) remotely. The vehicle can be launched from a small boat and can travel at ~ 1 kt to locations offshore. We have adapted a Wave Glider for seafloor geodesy by adding a dual frequency GPS receiver embedded in an Inertial Navigation Unit, a second GPS antenna/receiver to align the INU, and a high precision acoustic ranging system. We will report results of initial testing of the system conducted at SIO. In 2014, the new approach will be used for seafloor geodetic measurements of plate motion in the Cascadia Subduction Zone. The project is for a three-year effort to measure plate motion at three sites along an East-West profile at latitude 44.6 N, offshore Newport Oregon. One site will be located on the incoming plate to measure the present day convergence between the Juan de Fuca and North American plates and two additional sites will be located on the continental slope of NA to measure the elastic deformation due to stick-slip behavior on the mega-thrust fault. These new seafloor data will constrain existing models of slip behavior that presently are poorly constrained by land geodetic data 100 km from the deformation front.

  7. Dust-acoustic waves modulational instability and rogue waves in a polarized dusty plasma

    Bouzit, Omar; Tribeche, Mouloud [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria)

    2015-10-15

    The polarization force-induced changes in the dust-acoustic waves (DAWs) modulational instability (MI) are examined. Using the reductive perturbation method, the nonlinear Schrödinger equation that governs the MI of the DAWs is obtained. It is found that the effect of the polarization term R is to narrow the wave number domain for the onset of instability. The amplitude of the wave envelope decreases as R increases, meaning that the polarization force effects render weaker the associated DA rogue waves. The latter may therefore completely damp in the vicinity of R ∼ 1, i.e., as the polarization force becomes close to the electrostatic one (the net force acting on the dust particles becomes vanishingly small). The DA rogue wave profile is very sensitive to any change in the restoring force acting on the dust particles. It turns out that the polarization effects may completely smear out the DA rogue waves.

  8. Circuit Design of Surface Acoustic Wave Based Micro Force Sensor

    Yuanyuan Li

    2014-01-01

    Full Text Available Pressure sensors are commonly used in industrial production and mechanical system. However, resistance strain, piezoresistive sensor, and ceramic capacitive pressure sensors possess limitations, especially in micro force measurement. A surface acoustic wave (SAW based micro force sensor is designed in this paper, which is based on the theories of wavelet transform, SAW detection, and pierce oscillator circuits. Using lithium niobate as the basal material, a mathematical model is established to analyze the frequency, and a peripheral circuit is designed to measure the micro force. The SAW based micro force sensor is tested to show the reasonable design of detection circuit and the stability of frequency and amplitude.

  9. Acoustic measurements above a plate carrying Lamb waves

    Talberg, Andreas Sørbrøden

    2016-01-01

    This article presents a set of acoustic measurements conducted on the Statoil funded Behind Casing Logging Set-Up, designed by SINTEF Petroleum Research to resemble an oil well casing. A set of simple simulations using COMSOL Multiphysics were also conducted and the results compared with the measurements. The experiments consists of measuring the pressure wave radiated of a set of Lamb waves propagating in a 3 mm thick steel plate, using the so called pitch-catch method. The Lamb waves were excited by a broadband piezoelectric immersion transducer with center frequency of 1 MHz. Through measurements and analysis the group velocity of the fastest mode in the plate was found to be 3138.5 m/s. Measuring the wave radiated into the water in a grid consisting of 8x33 measuring points, the spreading of the plate wave normal to the direction of propagation was investigated. Comparing the point where the amplitude had decreased 50 % relative to the amplitude measured at the axis pointing straight forward from the tran...

  10. Helioseismology and asteroseismology: looking for gravitational waves in acoustic oscillations

    Lopes, Ilídio [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Silk, Joseph, E-mail: ilidio.lopes@tecnico.ulisboa.pt, E-mail: ilopes@uevora.pt, E-mail: silk@astro.ox.ac.uk [Institut d' Astrophysique de Paris, UMR 7095 CNRS, Université Pierre et Marie Curie, 98 bis Boulevard Arago, Paris 75014 (France)

    2014-10-10

    Current helioseismology observations allow the determination of the frequencies and surface velocity amplitudes of solar acoustic modes with exceptionally high precision. In some cases, the frequency accuracy is better than one part in a million. We show that there is a distinct possibility that quadrupole acoustic modes of low order could be excited by gravitational waves (GWs), if the GWs have a strain amplitude in the range 10{sup –20} h {sub –20} with h {sub –20} ∼ 1 or h {sub –20} ∼ 10{sup 3}, as predicted by several types of GW sources, such as galactic ultracompact binaries or extreme mass ratio inspirals and coalescence of black holes. If the damping rate at low order is 10{sup –3}η {sub N} μHz, with η {sub N} ∼ 10{sup –3}-1, as inferred from the theory of stellar pulsations, then GW radiation will lead to a maximum rms surface velocity amplitude of quadrupole modes of the order of h{sub −20}η{sub N}{sup −1}∼ 10{sup –9}-10{sup –3} cm s{sup –1}, on the verge of what is currently detectable via helioseismology. The frequency and sensitivity range probed by helioseismological acoustic modes overlap with, and complement, the capabilities of eLISA for the brightest resolved ultracompact galactic binaries.

  11. Gravitational Wave Detection with High Frequency Phonon Trapping Acoustic Cavities

    Goryachev, Maxim

    2014-01-01

    There are a number of theoretical predictions for astrophysical and cosmological objects, which emit high frequency ($10^6-10^9$~Hz) Gravitation Waves (GW) or contribute somehow to the stochastic high frequency GW background. Here we propose a new sensitive detector in this frequency band, which is based on existing cryogenic ultra-high quality factor quartz Bulk Acoustic Wave cavity technology, coupled to near-quantum-limited SQUID amplifiers at $20$~mK. We show that spectral strain sensitivities reaching $10^{-22}$ per $\\sqrt{\\text{Hz}}$ per mode is possible, which in principle can cover the frequency range with multiple ($>100$) modes with quality factors varying between $10^6-10^{10}$ allowing wide bandwidth detection. Due to its compactness and well established manufacturing process, the system is easily scalable into arrays and distributed networks that can also impact the overall sensitivity and introduce coincidence analysis to ensure no false detections.

  12. Dromion solutions for nonlinear electron acoustic waves in space plasmas

    S. S. Ghosh

    2002-01-01

    Full Text Available Recent high resolution measurements of POLAR and FAST satellites have revealed two-dimensional coherent structures in the polar cap boundary layer (PCBL region. Since the ion temperature is often observed to be greater than the electron temperature in this region, electron acoustic waves can exist as a normal mode of the plasma system. It is shown that the nonlinear evolution of such waves can be modelled by the coupled Davey-Stewartson I equations. These equations, which are a generalization of the nonlinear Schrödinger equation to two dimensions, admit exponentially localized solutions called dromions. A detailed parametric characterization of the regions of existence of such solutions is presented in the context of the PCBL region.

  13. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  14. Weakly dissipative dust-ion acoustic wave modulation

    Alinejad, H.; Mahdavi, M.; Shahmansouri, M.

    2016-01-01

    The modulational instability of dust-ion acoustic (DIA) waves in an unmagnetized dusty plasma is investigated in the presence of weak dissipations arising due to the low rates (compared to the ion oscillation frequency) of ionization recombination and ion loss. Based on the multiple space and time scales perturbation, a new modified nonlinear Schrödinger equation governing the evolution of modulated DIA waves is derived with a linear damping term. It is shown that the combined action of all dissipative mechanisms due to collisions between particles reveals the permitted maximum time for the occurrence of the modulational instability. The influence on the modulational instability regions of relevant physical parameters such as ion temperature, dust concentration, ionization, recombination and ion loss is numerically examined. It is also found that the recombination frequency controls the instability growth rate, whereas recombination and ion loss make the instability regions wider.

  15. Experimental and numerical studies on standing surface acoustic wave microfluidics.

    Mao, Zhangming; Xie, Yuliang; Guo, Feng; Ren, Liqiang; Huang, Po-Hsun; Chen, Yuchao; Rufo, Joseph; Costanzo, Francesco; Huang, Tony Jun

    2016-02-01

    Standing surface acoustic waves (SSAW) are commonly used in microfluidics to manipulate cells and other micro/nano particles. However, except for a simple one-dimensional (1D) harmonic standing waves (HSW) model, a practical model that can predict particle behaviour in SSAW microfluidics is still lacking. Herein, we established a two-dimensional (2D) SSAW microfluidic model based on the basic theory in acoustophoresis and our previous modelling strategy to predict the acoustophoresis of microparticles in SSAW microfluidics. This 2D SSAW microfluidic model considers the effects of boundary vibrations, channel materials, and channel dimensions on the acoustic propagation; as an experimental validation, the acoustophoresis of microparticles under continuous flow through narrow channels made of PDMS and silicon was studied. The experimentally observed motion of the microparticles matched well with the numerical predictions, while the 1D HSW model failed to predict many of the experimental observations. Particularly, the 1D HSW model cannot account for particle aggregation on the sidewall in PDMS channels, which is well explained by our 2D SSAW microfluidic model. Our model can be used for device design and optimization in SSAW microfluidics. PMID:26698361

  16. Calculation of surface acoustic waves in a multilayered piezoelectric structure

    Zhang Zuwei; Wen Zhiyu; Hu Jing

    2013-01-01

    The propagation properties of the surface acoustic waves (SAWs) in a ZnO-SiO2-Si multilayered piezoelectric structure are calculated by using the recursive asymptotic method.The phase velocities and the electromechanical coupling coefficients for the Rayleigh wave and the Love wave in the different ZnO-SiO2-Si structures are calculated and analyzed.The Love mode wave is found to be predominantly generated since the c-axis of the ZnO film is generally perpendicular to the substrate.In order to prove the calculated results,a Love mode SAW device based on the ZnO-SiO2-Si multilayered structure is fabricated by micromachining,and its frequency responses are detected.The experimental results are found to be mainly consistent with the calculated ones,except for the slightly larger velocities induced by the residual stresses produced in the fabrication process of the films.The deviation of the experimental results from the calculated ones is reduced by thermal annealing.

  17. Suppression of Raman gain by finite level ion acoustic waves in inhomogeneous plasma

    We have examined a complex five-wave Raman scattering event in an inhomogeneous plasma in the presence of a finite level of ion acoustic waves. The first phase involves conventional three-wave stimulated Raman scattering, followed by the decay of the Raman Langmuir wave into either a second Langmuir wave (LDI) or a second scattered light wave (EDI) and an ion acoustic wave, assumed present at a non-thermal level. These decays take place locally so that matching conditions for Raman scattering and the subsidiary decay are coincident. We have shown that the complex Raman gain is sensitive to the source levels for the amplifying waves. For LDI the gain may be suppressed or enhanced depending on the relative intensities of the two Langmuir waves while for EDI the gain is invariably suppressed. Only a very modest level of ion acoustic waves is necessary for this to occur. (authors)

  18. Ion acoustic wave collapse via two-ion wave decay: 2D Vlasov simulation and theory

    Chapman, Thomas; Berger, Richard; Banks, Jeffrey; Brunner, Stephan

    2015-11-01

    The decay of ion acoustic waves (IAWs) via two-ion wave decay may transfer energy from the electric field of the IAWs to the particles, resulting in a significant heating of resonant particles. This process has previously been shown in numerical simulations to decrease the plasma reflectivity due to stimulated Brillouin scattering. Two-ion wave decay is a fundamental property of ion acoustic waves that occurs over most if not all of the parameter space of relevance to inertial confinement fusion experiments, and can lead to a sudden collapse of IAWs. The treatment of all species kinetically, and in particular the electrons, is required to describe the decay process correctly. We present fully kinetic 2D+2V Vlasov simulations of IAWs undergoing decay to a highly nonlinear turbulent state using the code LOKI. The scaling of the decay rate with characteristic plasma parameters and wave amplitude is shown. A new theory describing two-ion wave decay in 2D, that incorporates key kinetic properties of the electrons, is presented and used to explain quantitatively for the first time the observed decay of IAWs. Work performed under auspices of U.S. DoE by LLNL, Contract DE-AC52-07NA2734. Funded by LDRD 15-ERD-038 and supported by LLNL Grand Challenge allocation.

  19. Modified ion-acoustic solitary waves in plasmas with field-aligned shear flows

    Saleem, H. [Department of Space Science, Institute of Space Technology, 1-Islamabad Highway, Islamabad (Pakistan); Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); Ali, S. [Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); National Centre for Physics (NCP) at Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Haque, Q. [Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); National Centre for Physics (NCP) at Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Theoretical Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)

    2015-08-15

    The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Korteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration.

  20. Modified ion-acoustic solitary waves in plasmas with field-aligned shear flows

    The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Korteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration

  1. Influence of acoustic waves on Radiation Spectra of Argon Gas-discharge Plasma

    Aramyan, A R

    2002-01-01

    It is shown that under the definite regime of interaction of the acoustic waves with low-temperature, partially ionized plasma it is possible to change the intensity of some spectral lines of atomic argon. It is shown also, that the dependence of the intensities of these spectral lines on the intensity of the acoustic wave has a hysteresis behavior.

  2. Double aperture focusing transducer for controlling microparticle motions in trapezoidal microchannels with surface acoustic waves

    Tan, Ming K.; Tjeung, Ricky; Ervin, Hannah; Yeo, Leslie Y.; Friend, James

    2009-09-01

    We present a method for controlling the motion of microparticles suspended in an aqueous solution, which fills in a microchannel fabricated into a piezoelectric substrate, using propagating surface acoustic waves. The cross-sectional shape of this microchannel is trapezoidal, preventing the formation of acoustic standing waves across the channel width and therefore allowing the steering of microparticles. The induced acoustic streaming transports these particles to eliminate the use of external pumps for fluid actuation.

  3. Coherent scattering of CO2 light from ion-acoustic waves

    Scattering of laser radiation from ion-acoustic waves in a plasma is investigated analytically and experimentally. The formulation predicts a coherent component of the scattered power on a largely incoherent background spectrum when the acoustic analog of Bragg's law and Doppler shift conditions are satisfied. The experiment consists of a hybrid CO2 laser system capable of either low power continuous wave or high power pulsed mode operation. A heterodyne light mixing scheme is used to detect the scattered power. The proportionality predicted by the theory is verified by scattering from externally excited acoustic and ion-acoustic waves; continuous wave and pulsed modes in each case. Measurement of the ion-acoustic dispersion relation by continuous wave scattering is also presented

  4. ANALYTICAL SOLUTION FOR WAVES IN PLANETS WITH ATMOSPHERIC SUPERROTATION. I. ACOUSTIC AND INERTIA-GRAVITY WAVES

    This paper is the first of a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting with the primitive equations for a cyclostrophic regime, we have deduced the analytical solution for the possible waves, simultaneously including the effect of the metric terms for the centrifugal force and the meridional shear of the background wind. In those cases when the conditions for the method of the multiple scales in height are met, these wave solutions are also valid when vertical shear of the background wind is present. A total of six types of waves have been found and their properties were characterized in terms of the corresponding dispersion relations and wave structures. In this first part, only waves that are direct solutions of the generic dispersion relation are studied—acoustic and inertia-gravity waves. Concerning inertia-gravity waves, we found that in the cases of short horizontal wavelengths, null background wind, or propagation in the equatorial region, only pure gravity waves are possible, while for the limit of large horizontal wavelengths and/or null static stability, the waves are inertial. The correspondence between classical atmospheric approximations and wave filtering has been examined too, and we carried out a classification of the mesoscale waves found in the clouds of Venus at different vertical levels of its atmosphere. Finally, the classification of waves in exoplanets is discussed and we provide a list of possible candidates with cyclostrophic regimes

  5. ANALYTICAL SOLUTION FOR WAVES IN PLANETS WITH ATMOSPHERIC SUPERROTATION. I. ACOUSTIC AND INERTIA-GRAVITY WAVES

    Peralta, J.; López-Valverde, M. A. [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía, 18008 Granada (Spain); Imamura, T. [Institute of Space and Astronautical Science-Japan Aerospace Exploration Agency 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Read, P. L. [Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford (United Kingdom); Luz, D. [Centro de Astronomia e Astrofísica da Universidade de Lisboa (CAAUL), Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa (Portugal); Piccialli, A., E-mail: peralta@iaa.es [LATMOS, UVSQ, 11 bd dAlembert, 78280 Guyancourt (France)

    2014-07-01

    This paper is the first of a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting with the primitive equations for a cyclostrophic regime, we have deduced the analytical solution for the possible waves, simultaneously including the effect of the metric terms for the centrifugal force and the meridional shear of the background wind. In those cases when the conditions for the method of the multiple scales in height are met, these wave solutions are also valid when vertical shear of the background wind is present. A total of six types of waves have been found and their properties were characterized in terms of the corresponding dispersion relations and wave structures. In this first part, only waves that are direct solutions of the generic dispersion relation are studied—acoustic and inertia-gravity waves. Concerning inertia-gravity waves, we found that in the cases of short horizontal wavelengths, null background wind, or propagation in the equatorial region, only pure gravity waves are possible, while for the limit of large horizontal wavelengths and/or null static stability, the waves are inertial. The correspondence between classical atmospheric approximations and wave filtering has been examined too, and we carried out a classification of the mesoscale waves found in the clouds of Venus at different vertical levels of its atmosphere. Finally, the classification of waves in exoplanets is discussed and we provide a list of possible candidates with cyclostrophic regimes.

  6. An acoustic wave equation for pure P wave in 2D TTI media

    Zhan, Ge

    2011-01-01

    In this paper, a pure P wave equation for an acoustic 2D TTI media is derived. Compared with conventional TTI coupled equations, the resulting equation is unconditionally stable due to the complete isolation of the SV wave mode. To avoid numerical dispersion and produce high quality images, the rapid expansion method REM is employed for numerical implementation. Synthetic results validate the proposed equation and show that it is a stable algorithm for modeling and reverse time migration RTM in a TTI media for any anisotropic parameter values. © 2011 Society of Exploration Geophysicists.

  7. Ion acoustic waves in multi-species plasmas

    This thesis is concerned with the propagation of small amplitude ion acoustic waves through plasmas consisting of electrons and two species of ions, each with a Maxwellian velocity distribution function. The dispersion relation, derived from the Vlasov and Poisson equations, can easily be solved by numerical methods. The thesis is divided into two parts: 1. Stationary ions: when the average velocities of all the species are zero, the waves propagate in two different ways depending on electron-to-ion temperature ratio Theta, heavy-to-light ion mass ratio M, and the light ion concentation f. Either the principal mode in two different ways of the pure heavy ion plasma can be traced continuously to the principal mode of the light ion plasma as the proportion of light ions is steadily increased, or it becomes unobservable due to damping, while a second wave appears and develops into the principal light ion mode. It is shown that critical values of f and Theta governing this behaviour are associated with certain saddle points in the dielectric function. 2. Ion beams: If a mixture of ions is electrostatically accelerated, the two species assume different velocities and an instability may develop. The dependence of marginal stability on Theta, M and f and accelerating voltage E is investigated numerically. The unstable mode may be linked to the principal slow mode of the light ion beam. Higher order mode behaviour is also investigated, and the angular dependence of the instability in three dimensions is discussed. In both cases, a degeneracy appears in the dispersion relation at critical values of parameters. The excitation level of the waves is then very large. This phenomenon is interpreted as a resonance between the two species supporting the wave

  8. A Schamel equation for ion acoustic waves in superthermal plasmas

    Williams, G., E-mail: gwilliams06@qub.ac.uk; Kourakis, I. [Centre for Plasma Physics, Department of Physics and Astronomy, Queen' s University Belfast, BT7 1NN, Northern Ireland (United Kingdom); Verheest, F. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Hellberg, M. A. [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Anowar, M. G. M. [Department of Physics, Begum Rokeya University, Rangpur, Rangpur-5400 (Bangladesh)

    2014-09-15

    An investigation of the propagation of ion acoustic waves in nonthermal plasmas in the presence of trapped electrons has been undertaken. This has been motivated by space and laboratory plasma observations of plasmas containing energetic particles, resulting in long-tailed distributions, in combination with trapped particles, whereby some of the plasma particles are confined to a finite region of phase space. An unmagnetized collisionless electron-ion plasma is considered, featuring a non-Maxwellian-trapped electron distribution, which is modelled by a kappa distribution function combined with a Schamel distribution. The effect of particle trapping has been considered, resulting in an expression for the electron density. Reductive perturbation theory has been used to construct a KdV-like Schamel equation, and examine its behaviour. The relevant configurational parameters in our study include the superthermality index κ and the characteristic trapping parameter β. A pulse-shaped family of solutions is proposed, also depending on the weak soliton speed increment u{sub 0}. The main modification due to an increase in particle trapping is an increase in the amplitude of solitary waves, yet leaving their spatial width practically unaffected. With enhanced superthermality, there is a decrease in both amplitude and width of solitary waves, for any given values of the trapping parameter and of the incremental soliton speed. Only positive polarity excitations were observed in our parametric investigation.

  9. Multiple scattering of a spherical acoustic wave from fluid spheres

    Wu, J. H.; Liu, A. Q.; Chen, H. L.; Chen, T. N.

    2006-02-01

    The multiple scattering of a spherical acoustic wave from an arbitrary number of fluid spheres is investigated theoretically. The tool to attack the multiple scattering problem is a kind of addition formulas for the spherical wave functions, which are presented in the paper, based on the bicentric expansion form of Green function in the spherical coordinates. For an arbitrary configuration of N fluid spheres, the kind of addition formulas permits the field expansions (all referred to the center of each sphere). With these the sound fields scattered by each sphere can be described by a set of N equations. The interactions between any two fluid spheres are taken into account in these equations exactly and their coefficients are coupled through double sums in the spherical wave functions. By truncating the infinite series in the equations depending on certain calculation accuracy and solving the coefficients matrix by using the Gauss-Seidel iteration method, we can obtain the scattered sound field by the configuration of the fluid spheres. Finally, the scattering calculations by using the kind of addition formulas are carried out.

  10. The shock-acoustic waves generated by the earthquakes

    Afraimovich, E L; Plotnikov, A V; Uralov, A M

    2000-01-01

    We investigate the form and dynamics of shock-acoustic waves generated by earthquakes. We use the method for detecting and locating the sources of ionospheric impulsive disturbances, based on using data from a global network of receivers of the GPS navigation system and requiring no a priori information about the place and time of associated effects. The practical implementation of the method is illustrated by a case study of earthquake effects in Turkey in 1999. It was found that in all instances the ionospheric response has the character of an N-wave. The period is 180-390 s, and the amplitude exceeds by a factor of two as a minimum the standard deviation of background fluctuations in total electron content in this range of periods under quite and moderate geomagnetic conditions. The elevation of the wave vector varies through a range of 20-44 degree, and the phase velocity (1100-1300 m/s) approaches the sound velocity at the heights of the ionospheric F-region maximum. The calculated (by neglecting refract...

  11. Dust-acoustic solitary waves in a dusty plasma with two-temperature nonthermal ions

    Zhi-Jian Zhou; Hong-Yan Wang; Kai-Biao Zhang

    2012-01-01

    By using reductive perturbation method, the nonlinear propagation of dust-acoustic waves in a dusty plasma (containing a negatively charged dust fluid, Boltzmann distributed electrons and two-temperature nonthermal ions) is investigated. The effects of two-temperature nonthermal ions on the basic properties of small but finite amplitude nonlinear dust-acoustic waves are examined. It is found that two-temperature nonthermal ions affect the basic properties of the dust-acoustic solitary waves. It is also observed that only compressive solitary waves exist in this system.

  12. Statistical Analysis of Acoustic Wave Parameters Near Solar Active Regions

    Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.

    2016-08-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.

  13. Nonlinear interaction of kinetic Alfvén waves and ion acoustic waves in coronal loops

    Sharma, Prachi; Yadav, Nitin; Sharma, R. P.

    2016-05-01

    Over the years, coronal heating has been the most fascinating question among the scientific community. In the present article, a heating mechanism has been proposed based on the wave-wave interaction. Under this wave-wave interaction, the high frequency kinetic Alfvén wave interacts with the low frequency ion acoustic wave. These waves are three dimensionally propagating and nonlinearly coupled through ponderomotive nonlinearity. A numerical code based on pseudo-spectral technique has been developed for solving these normalized dynamical equations. Localization of kinetic Alfvén wave field has been examined, and magnetic power spectrum has also been analyzed which shows the cascading of energy to higher wavenumbers, and this cascading has been found to have Kolmogorov scaling, i.e., k-5 /3 . A breakpoint appears after Kolmogorov scaling and next to this spectral break; a steeper scaling has been obtained. The presented nonlinear interaction for coronal loops plasmas is suggested to generate turbulent spectrum having Kolmogorov scaling in the inertial range and steepened scaling in the dissipation range. Since Kolmogorov turbulence is considered as the main source for coronal heating; therefore, the suggested mechanism will be a useful tool to understand the mystery of coronal loop heating through Kolmogorov turbulence and dissipation.

  14. Flow induced dust acoustic shock waves in a complex plasma

    Jaiswal, Surabhi; Bandyopadhyay, Pintu; Sen, Abhijit

    2015-11-01

    We report on experimental observations of particle flow induced large amplitude shock waves in a dusty plasma. These dust acoustic shocks (DAS) are observed for strongly supersonic flows and have been studied in a U-shaped Dusty Plasma Experimental (DPEx) device for charged kaolin dust in a background of Argon plasma. The strong flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change of the dust density near the potential hill is used to trigger the onset of high velocity dust acoustic shocks. The dynamics of the shocks are captured by fast video pictures of the structures that are illuminated by a laser sheet beam. The physical characteristics of the shock are delineated from a parametric scan of their dynamical properties over a range of plasma parameters and flow speeds. Details of these observations and a physical explanation based on model calculations will be presented.

  15. Statistical analysis of acoustic wave parameters near active regions

    Soares, M Cristina Rabello; Scherrer, Philip H

    2016-01-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyse the differences in the parameters in magnetically quiet regions nearby an active region (which we call `nearby regions'), compared with those of quiet regions at the same disc locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring diagram analysis of all active regions observed by HMI during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhancement (the `acoustic halo effect') is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes...

  16. Heterogeneous Nucleation Induced by Capillary Wave During Acoustic Levitation

    吕勇军; 解文军; 魏炳波

    2003-01-01

    The rapid solidification of acoustically levitated drops of Pb-61.9 wt. %Sn eutectic alloy is accomplished. A surface morphology of spreading ripples is observed on a sample undercooled by 15 K. The ripples originate from the centre of sample surface, which is also the heterogeneous nucleation site for eutectic growth. The Faraday instability excited by forced surface vibration has brought about these ripples. They are retained in the solidified sample if the sound pressure level exceeds the threshold pressure required for the appearance of capillary waves.Theoretical calculations indicate that both the pressure and displacement maxima exist in the central part of a levitated drop. The pressure near the sample centre can promote heterogeneous nucleation, which is in agreement qualitatively with the experimental results.

  17. Effect of the streamed negative ions on dust acoustic waves

    The propagation of streaming negative ions in the dust acoustic waves (DAWs) is investigated, including nonlinear effects such as dust charge fluctuation, dust temperature, and the negative ions. The streaming velocity of the negative ions played an essential and effective role in the DAWs characteristics. The dust charge fluctuation shows a remarkable decrease with the negative ions concentration decrement. Increasing of negative ions temperature causes an increase of the dust charge for different ratios of streaming velocity to thermal velocity (υ). Also, both of the amplitude and the width of the soliton solutions have shown strong dependence on υ as well as on the negative ions concentration. The results of this study will be useful for a better understanding of crystallization in dust plasma, especially phase transition governed from fluid state to solid state, and in a variety of modern technology applications such as fabrication of the semiconductor. (author)

  18. Investigation of surface acoustic waves in laser shock peened metals

    Ling Yuan; Gang Yan; Zhonghua Shen; Hangwei Xu; Xiaowu Ni; Jian Lu

    2008-01-01

    Laser shock peening is a well-known method for extending the fatigue life of metal components by introducing near-surface compressive residual stress. The surface acoustic waves (SAWs) are dispersive when the near-surface properties of materials are changed. So the near-surface properties (such as the thickness of hardened layers, elastic properties, residual stresses, etc.) can be analyzed by the phase velocity dispersion. To study the propagation of SAWs in metal samples after peening, a more reasonable experimental method of broadband excitation and reception is introduced. The ultrasonic signals are excited by laser and received by polyvinylindene fluoride (PVDF) transducer. The SAW signals in aluminum alloy materials with different impact times by laser shock peening are detected. Signal spectrum and phase velocity dispersion curves of SAWs are analyzed. Moreover, reasons for dispersion are discussed.

  19. Multilayer-graphene-based amplifier of surface acoustic waves

    The amplification of surface acoustic waves (SAWs) by a multilayer graphene (MLG)-based amplifier is studied. The conductivity of massless carriers (electrons or holes) in graphene in an external drift electric field is calculated using Boltzmann’s equation. At some carrier drift velocities, the real part of the variable conductivity becomes negative and MLG can be employed in SAW amplifiers. Amplification of Blustein’s and Rayleigh’s SAWs in CdS, a piezoelectric hexagonal crystal of the symmetry group C6v, is considered. The corresponding equations for SAW propagation in the device are derived and can be applied to other substrate crystals of the same symmetry. The results of the paper indicate that MLG can be considered as a perspective material for SAW amplification and related applications

  20. Surface acoustic waves in piezoelectrics with HTSC resonance film structure

    Analysis of surface acoustic wave (SAW) propagation in a periodic film structure of granulated high-temperature superconductor formed on the piezoelectric surface, is conducted. A number of notable features in the SAW characteristics is revealed. SAW parameter dependences on frequency and temperature can be of a resonance character in the region of N-S transition, in a zone, where Josephson currents on intergranular contacts of a superconductor prevail. Evaluations have shown that the resonance peak of attenuation can achieve the value of 100 decibel/cm, and SAW velocity difference in the region of resonance ΔV/V can exceed 10-2. A sharp temperature dependence of these parameters allows one to use the effects to construct bolometric acoustoelectron photoreceivers and other sensors. 9 refs.; 5 figs

  1. Meshless RBF based pseudospectral solution of acoustic wave equation

    Mishra, Pankaj K

    2015-01-01

    Chebyshev pseudospectral (PS) methods are reported to provide highly accurate solution using polynomial approximation. Use of polynomial basis functions in PS algorithms limits the formulation to univariate systems constraining it to tensor product grids for multi-dimensions. Recent studies have shown that replacing the polynomial by radial basis functions in pseudospectral method (RBF-PS) has the advantage of using irregular grids for multivariate systems. A RBF-PS algorithm has been presented here for the numerical solution of inhomogeneous Helmholtz's equation using Gaussian RBF for derivative approximation. Efficacy of RBF approximated derivatives has been checked through error analysis comparison with PS method. Comparative study of PS, RBF-PS and finite difference approach for the solution of a linear boundary value problem has been performed. Finally, a typical frequency domain acoustic wave propagation problem has been solved using Dirichlet boundary condition and a point source. The algorithm present...

  2. Multilayer-graphene-based amplifier of surface acoustic waves

    Stanislav O. Yurchenko

    2015-05-01

    Full Text Available The amplification of surface acoustic waves (SAWs by a multilayer graphene (MLG-based amplifier is studied. The conductivity of massless carriers (electrons or holes in graphene in an external drift electric field is calculated using Boltzmann’s equation. At some carrier drift velocities, the real part of the variable conductivity becomes negative and MLG can be employed in SAW amplifiers. Amplification of Blustein’s and Rayleigh’s SAWs in CdS, a piezoelectric hexagonal crystal of the symmetry group C6v, is considered. The corresponding equations for SAW propagation in the device are derived and can be applied to other substrate crystals of the same symmetry. The results of the paper indicate that MLG can be considered as a perspective material for SAW amplification and related applications.

  3. Multilayer-graphene-based amplifier of surface acoustic waves

    Yurchenko, Stanislav O., E-mail: st.yurchenko@mail.ru; Komarov, Kirill A. [Bauman Moscow State Technical University, 2-nd Baumanskaya str. 5, Moscow 105005 (Russian Federation); Pustovoit, Vladislav I. [Scientific and Technological Center of Unique Instrumentation, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-05-15

    The amplification of surface acoustic waves (SAWs) by a multilayer graphene (MLG)-based amplifier is studied. The conductivity of massless carriers (electrons or holes) in graphene in an external drift electric field is calculated using Boltzmann’s equation. At some carrier drift velocities, the real part of the variable conductivity becomes negative and MLG can be employed in SAW amplifiers. Amplification of Blustein’s and Rayleigh’s SAWs in CdS, a piezoelectric hexagonal crystal of the symmetry group C{sub 6v}, is considered. The corresponding equations for SAW propagation in the device are derived and can be applied to other substrate crystals of the same symmetry. The results of the paper indicate that MLG can be considered as a perspective material for SAW amplification and related applications.

  4. [INVITED] Laser generation and detection of ultrafast shear acoustic waves in solids and liquids

    Pezeril, Thomas

    2016-09-01

    The aim of this article is to provide an overview of the up-to-date findings related to ultrafast shear acoustic waves. Recent progress obtained for the laser generation and detection of picosecond shear acoustic waves in solids and liquids is reviewed. Examples in which the transverse isotropic symmetry of the sample structure is broken in order to permit shear acoustic wave generation through sudden laser heating are described in detail. Alternative photo-induced mechanisms for ultrafast shear acoustic generation in metals, semiconductors, insulators, magnetostrictive, piezoelectric and electrostrictive materials are reviewed as well. With reference to key experiments, an all-optical technique employed to probe longitudinal and shear structural dynamics in the GHz frequency range in ultra-thin liquid films is described. This technique, based on specific ultrafast shear acoustic transducers, has opened new perspectives that will be discussed for ultrafast shear acoustic probing of viscoelastic liquids at the nanometer scale.

  5. Study of nonlinear ion- and electron-acoustic waves in multi-component space plasmas

    G. S. Lakhina

    2008-11-01

    Full Text Available Large amplitude ion-acoustic and electron-acoustic waves in an unmagnetized multi-component plasma system consisting of cold background electrons and ions, a hot electron beam and a hot ion beam are studied using Sagdeev pseudo-potential technique. Three types of solitary waves, namely, slow ion-acoustic, ion-acoustic and electron-acoustic solitons are found provided the Mach numbers exceed the critical values. The slow ion-acoustic solitons have the smallest critical Mach numbers, whereas the electron-acoustic solitons have the largest critical Mach numbers. For the plasma parameters considered here, both type of ion-acoustic solitons have positive potential whereas the electron-acoustic solitons can have either positive or negative potential depending on the fractional number density of the cold electrons relative to that of the ions (or total electrons number density. For a fixed Mach number, increases in the beam speeds of either hot electrons or hot ions can lead to reduction in the amplitudes of the ion-and electron-acoustic solitons. However, the presence of hot electron and hot ion beams have no effect on the amplitudes of slow ion-acoustic modes. Possible application of this model to the electrostatic solitary waves (ESWs observed in the plasma sheet boundary layer is discussed.

  6. Universal instability of dust ion-sound waves and dust-acoustic waves

    It is shown that the dust ion-sound waves (DISW) and the dust-acoustic waves (DAW) are universally unstable for wave numbers less than some critical wave number. The basic dusty plasma state is assumed to be quasi-neutral with balance of the plasma particle absorption on the dust particles and the ionization with the rate proportional to the electron density. An analytical expression for the critical wave numbers, for the frequencies and for the growth rates of DISW and DAW are found using the hydrodynamic description of dusty plasma components with self-consistent treatment of the dust charge variations and by taking into account the change of the ion and electron distributions in the dust charging process. Most of the previous treatment do not take into account the latter process and do not treat the basic state self-consistently. The critical lengths corresponding to these critical wave numbers can be easily achieved in the existing experiments. It is shown that at the wave numbers larger than the critical ones DISW and DAW have a large damping which was not treated previously and which can be also measured. The instabilities found in the present work on their non linear stage can lead to formation of different types of dust self-organized structures. (author)

  7. Excitation of nonlinear ion acoustic waves in CH plasmas

    Feng, Q S; Liu, Z J; Xiao, C Z; Wang, Q; He, X T

    2016-01-01

    Excitation of nonlinear ion acoustic wave (IAW) by an external electric field is demonstrated by Vlasov simulation. The frequency calculated by the dispersion relation with no damping is verified much closer to the resonance frequency of the small-amplitude nonlinear IAW than that calculated by the linear dispersion relation. When the wave number $ k\\lambda_{De} $ increases, the linear Landau damping of the fast mode (its phase velocity is greater than any ion's thermal velocity) increases obviously in the region of $ T_i/T_e < 0.2 $ in which the fast mode is weakly damped mode. As a result, the deviation between the frequency calculated by the linear dispersion relation and that by the dispersion relation with no damping becomes larger with $k\\lambda_{De}$ increasing. When $k\\lambda_{De}$ is not large, such as $k\\lambda_{De}=0.1, 0.3, 0.5$, the nonlinear IAW can be excited by the driver with the linear frequency of the modes. However, when $k\\lambda_{De}$ is large, such as $k\\lambda_{De}=0.7$, the linear ...

  8. Mechanically robust microfluidics and bulk wave acoustics to sort microparticles

    Dauson, Erin R.; Gregory, Kelvin B.; Greve, David W.; Healy, Gregory P.; Oppenheim, Irving J.

    2016-04-01

    Sorting microparticles (or cells, or bacteria) is significant for scientific, medical and industrial purposes. Research groups have used lithium niobate SAW devices to produce standing waves, and then to align microparticles at the node lines in polydimethylsiloxane (PDMS, silicone) microfluidic channels. The "tilted angle" (skewed) configuration is a recent breakthrough producing particle trajectories that cross multiple node lines, making it practical to sort particles. However, lithium niobate wafers and PDMS microfluidic channels are not mechanically robust. We demonstrate "tilted angle" microparticle sorting in novel devices that are robust, rapidly prototyped, and manufacturable. We form our microfluidic system in a rigid polymethyl methacrylate (PMMA, acrylic) prism, sandwiched by lead-zirconium-titanate (PZT) wafers, operating in through-thickness mode with inertial backing, that produce standing bulk waves. The overall configuration is compact and mechanically robust, and actuating PZT wafers in through-thickness mode is highly efficient. Moving to this novel configuration introduced new acoustics questions involving internal reflections, but we show experimental images confirming the intended nodal geometry. Microparticles in "tilted angle" devices display undulating trajectories, where deviation from the straight path increases with particle diameter and with excitation voltage to create the mechanism by which particles are sorted. We show a simplified analytical model by which a "phase space" is constructed to characterize effective particle sorting, and we compare our experimental data to the predictions from that simplified model; precise correlation is not expected and is not observed, but the important physical trends from the model are paralleled in the measured particle trajectories.

  9. The dust acoustic waves in three dimensional scalable complex plasma

    Zhukhovitskii, D I

    2015-01-01

    Dust acoustic waves in the bulk of a dust cloud in complex plasma of low pressure gas discharge under microgravity conditions are considered. The dust component of complex plasma is assumed a scalable system that conforms to the ionization equation of state (IEOS) developed in our previous study. We find singular points of this IEOS that determine the behavior of the sound velocity in different regions of the cloud. The fluid approach is utilized to deduce the wave equation that includes the neutral drag term. It is shown that the sound velocity is fully defined by the particle compressibility, which is calculated on the basis of the scalable IEOS. The sound velocities and damping rates calculated for different 3D complex plasmas both in ac and dc discharges demonstrate a good correlation with experimental data that are within the limits of validity of the theory. The theory provides interpretation for the observed independence of the sound velocity on the coordinate and for a weak dependence on the particle ...

  10. Thickness measurement of Ni thin film using dispersion characteristics of a surface acoustic wave

    In this study, we suggest a method to measure the thickness of thin films nondestructively using the dispersion characteristics of a surface acoustic wave propagating along the thin film surface. To measure the thickness of thin films, we deposited thin films with different thicknesses on a Si (100) wafer substrate by controlling the deposit time using the E-beam evaporation method. The thickness of the thin films was measured using a scanning electron microscope. Subsequently, the surface wave velocity of the thin films with different thicknesses was measured using the V(z) curve method of scanning acoustic microscopy. The correlation between the measured thickness and surface acoustic wave velocity was verified. The wave velocity of the film decreased as the film thickness increased. Therefore, thin film thickness can be determined by measuring the dispersion characteristics of the surface acoustic wave velocity.

  11. Evidence of slow magneto-acoustic waves in photospheric observations of a sunspot

    Zharkov, S; Erdélyi, R; Thompson, M J

    2009-01-01

    We show the observational evidence for the presence of MHD waves in the solar photosphere deduced from SOHO MDI Dopplergram velocity observations. The magneto-acoustic oscillations are observed as acoustic power enhancement in the sunspot umbra at high frequency bands in the velocity component transverse to the magnetic field. We use numerical modelling of the wave propagation through localised non-uniform magnetic field concentration along with the same filtering procedure as applied to the observations to identify the observed waves. Underpinned by the results of the numerical simulations we classify the observed oscillations as slow magneto-acoustic waves excited by the trapped sub-photospheric acoustic waves. We consider the potential application of the presented method as a diagnostic tool for magnetohelioseismology.

  12. Brillouin light scattering from surface acoustic waves in a subwavelength-diameter optical fibre.

    Beugnot, Jean-Charles; Lebrun, Sylvie; Pauliat, Gilles; Maillotte, Hervé; Laude, Vincent; Sylvestre, Thibaut

    2014-01-01

    Brillouin scattering in optical fibres is a fundamental interaction between light and sound with important implications ranging from optical sensors to slow and fast light. In usual optical fibres, light both excites and feels shear and longitudinal bulk elastic waves, giving rise to forward-guided acoustic wave Brillouin scattering and backward-stimulated Brillouin scattering. In a subwavelength-diameter optical fibre, the situation changes dramatically, as we here report with the first experimental observation of Brillouin light scattering from surface acoustic waves. These Rayleigh-type surface waves travel the wire surface at a specific velocity of 3,400 m s(-1) and backscatter the light with a Doppler shift of about 6 GHz. As these acoustic resonances are sensitive to surface defects or features, surface acoustic wave Brillouin scattering opens new opportunities for various sensing applications, but also in other domains such as microwave photonics and nonlinear plasmonics. PMID:25341638

  13. Kinetic study of ion acoustic twisted waves with kappa distributed electrons

    Arshad, Kashif; Aman-ur-Rehman, Mahmood, Shahzad

    2016-05-01

    The kinetic theory of Landau damping of ion acoustic twisted modes is developed in the presence of orbital angular momentum of the helical (twisted) electric field in plasmas with kappa distributed electrons and Maxwellian ions. The perturbed distribution function and helical electric field are considered to be decomposed by Laguerre-Gaussian mode function defined in cylindrical geometry. The Vlasov-Poisson equation is obtained and solved analytically to obtain the weak damping rates of the ion acoustic twisted waves in a non-thermal plasma. The strong damping effects of ion acoustic twisted waves at low values of temperature ratio of electrons and ions are also obtained by using exact numerical method and illustrated graphically, where the weak damping wave theory fails to explain the phenomenon properly. The obtained results of Landau damping rates of the twisted ion acoustic wave are discussed at different values of azimuthal wave number and non-thermal parameter kappa for electrons.

  14. Generation of thermo-acoustic waves from pulsed solar/IR radiation

    Rahman, Aowabin

    Acoustic waves could potentially be used in a wide range of engineering applications; however, the high energy consumption in generating acoustic waves from electrical energy and the cost associated with the process limit the use of acoustic waves in industrial processes. Acoustic waves converted from solar radiation provide a feasible way of obtaining acoustic energy, without relying on conventional nonrenewable energy sources. One of the goals of this thesis project was to experimentally study the conversion of thermal to acoustic energy using pulsed radiation. The experiments were categorized into "indoor" and "outdoor" experiments, each with a separate experimental setup. The indoor experiments used an IR heater to power the thermo-acoustic lasers and were primarily aimed at studying the effect of various experimental parameters on the amplitude of sound waves in the low frequency range (below 130 Hz). The IR radiation was modulated externally using a chopper wheel and then impinged on a porous solid, which was housed inside a thermo-acoustic (TA) converter. A microphone located at a certain distance from the porous solid inside the TA converter detected the acoustic signals. The "outdoor" experiments, which were targeted at TA conversion at comparatively higher frequencies (in 200 Hz-3 kHz range) used solar energy to power the thermo-acoustic laser. The amplitudes (in RMS) of thermo-acoustic signals obtained in experiments using IR heater as radiation source were in the 80-100 dB range. The frequency of acoustic waves corresponded to the frequency of interceptions of the radiation beam by the chopper. The amplitudes of acoustic waves were influenced by several factors, including the chopping frequency, magnitude of radiation flux, type of porous material, length of porous material, external heating of the TA converter housing, location of microphone within the air column, and design of the TA converter. The time-dependent profile of the thermo-acoustic signals

  15. Generation of surface acoustic wave by laser line array and its frequency characteristics

    Surface acoustic waves are very effective for the inspection of cracks and other defects in near-field region of the sample. Surface acoustic waves were generated by illumination of a sample surface with a Q-switched Nd:YAG laser pulse. A multiple slit and a cylindrical lens were used to generate the tone-burst like surface waves. Non contact detection of laser-generated surface acoustic waves was performed with the fiber optic Sagnac interferometer on a carbon steel specimen. Rayleigh wave velocity was obtained by the cross correlation of the signals recorded at different location, and was used to estimate the predominant frequency of the surface wave. Adjustment of the center frequency of the surface wave was performed by changing the distance between the sample and the lens, and the proper range for narrowband frequency was discussed.

  16. Experiments on the acoustic solitary wave generated thermoacoustically in a looped tube

    Shimizu, Dai; Sugimoto, Nobumasa

    2015-10-01

    Emergence of an acoustic solitary wave is demonstrated in a gas-filled, looped tube with an array of Helmholtz resonators connected. The solitary wave is generated thermoacoustically and spontaneously by a pair of stacks positioned diametrically on exactly the opposite side of the loop. The temperature gradient is imposed on both stacks in the same sense along the tube. The stacks made of ceramics and of many square pores are sandwiched by hot and cold heat exchangers. The pressure profile measured and the propagation speed show good agreements with the theoretical ones of the acoustic solitary wave obtained by Sugimoto (J. Acoust. Soc. Am., 99, 1971-1976 (1996)).

  17. Optical transition radiation in presence of acoustic waves for an oblique incidence

    Mkrtchyan, A R; Saharian, A A

    2011-01-01

    Forward transition radiation is considered in an ultrasonic superlattice excited in a finite thickness plate under oblique incidence of relativistic electrons. We investigate the influence of acoustic waves on both the intensity and polarization of the radiation. In the quasi-classical approximation, formulas are derived for the vector potential of the electromagnetic field and for the spectral-angular distribution of the radiation intensity. It is shown that the acoustic waves generate new resonance peaks in the spectral and angular distributions. The heights and the location of the peaks can be controlled by choosing the parameters of the acoustic wave. The numerical examples are given for a plate of fused quartz.

  18. Modulational instability of ion-acoustic waves in plasmas with superthermal electrons

    Using the reductive perturbation technique, the modulational instability of ion- acoustic waves in a plasma containing superthermal electrons is studied. It is found that the presence of superthermal electrons significantly changes the instability domain. A Lorentzian (kappa) velocity distribution function is used to model superthermal electrons. It is shown that the presence of superthermal electrons reduces the critical frequency of the modulational instability of ion-acoustic waves. Besides, due to the presence of the superthermal electrons, ion-acoustic waves are unstable on a vaster region. Moreover, the modulational instability growth rate is larger for a larger population of superthermal electrons.

  19. Effect of adiabatic variation of dust charges on dust acoustic solitary waves in magnetized dusty plasmas

    Duan Wen-Shan

    2004-01-01

    The effect of dust charging and the influence of its adiabatic variation on dust acoustic waves is investigated. By employing the reductive perturbation technique we derived a Zakharov-Kuznetsov (ZK) equation for small amplitude dust acoustic waves. We have analytically verified that there are only rarefactive solitary waves for this system. The instability region for one-dimensional solitary wave under transverse perturbations has also been obtained. The obliquely propagating solitary waves to the z-direction for the ZK equation are given in this paper as well.

  20. Parallel electric field in the auroral ionosphere: excitation of acoustic waves by Alfvén waves

    P. L. Israelevich

    2004-09-01

    Full Text Available We investigate a new mechanism for the formation of a parallel electric field observed in the auroral ionosphere. For this purpose, the excitation of acoustic waves by propagating Alfvén waves was studied numerically. We find that the magnetic pressure perturbation due to finite amplitude Alfvén waves causes the perturbation of the plasma pressure that propagates in the form of acoustic waves, and gives rise to a parallel electric field. This mechanism explains the observations of the strong parallel electric field in the small-scale electromagnetic perturbations of the auroral ionosphere. For the cases when the parallel electric current in the small-scale auroral perturbations is so strong that the velocity of current carriers exceeds the threshold of the ion sound instability, the excited ion acoustic waves may account for the parallel electric fields as strong as tens of mV/m.

  1. Overstability of acoustic waves in strongly magnetized anisotropic MHD shear flows

    Uchava, E. S.; B. M. Shergelashvili; Tevzadze, A. G.; Poedts, S.

    2014-01-01

    We present a linear stability analysis of the perturbation modes in anisotropic MHD flows with velocity shear and strong magnetic field. Collisionless or weakly collisional plasma is described within the 16-momentum MHD fluid closure model, that takes into account not only the effect of pressure anisotropy, but also the effect of anisotropic heat fluxes. In this model the low frequency acoustic wave is revealed into a standard acoustic mode and higher frequency fast thermo-acoustic and lower ...

  2. On-chip manipulation of single microparticles, cells, and organisms using surface acoustic waves

    Ding, Xiaoyun; Lin, Sz-Chin Steven; Kiraly, Brian; Yue, Hongjun; Li, Sixing; Chiang, I-Kao; Shi, Jinjie; Benkovic, Stephen J.; Huang, Tony Jun

    2012-01-01

    Techniques that can dexterously manipulate single particles, cells, and organisms are invaluable for many applications in biology, chemistry, engineering, and physics. Here, we demonstrate standing surface acoustic wave based “acoustic tweezers” that can trap and manipulate single microparticles, cells, and entire organisms (i.e., Caenorhabditis elegans) in a single-layer microfluidic chip. Our acoustic tweezers utilize the wide resonance band of chirped interdigital transducers to achieve re...

  3. Propagation of acoustic edge waves in graphene under quantum Hall effect

    Vikström, Anton

    2014-01-01

    We consider a graphene sheet with a zigzag edge subject to a perpendicular magnetic field and investigate the propagation of in-plane acoustic edge waves under the influence of magnetically induced electronic edge states. In particular is is shown that propagation is significantly blocked for certain frequencies defined by the resonant absorption due to electronic-acoustic interaction. We suggest that strong interaction between the acoustic and electronic edge states in graphene may generate ...

  4. Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor

    Leonhard Michael Reindl

    2013-02-01

    Full Text Available Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid—liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner.

  5. Enhanced acoustic sensing through wave compression and pressure amplification in anisotropic metamaterials.

    Chen, Yongyao; Liu, Haijun; Reilly, Michael; Bae, Hyungdae; Yu, Miao

    2014-01-01

    Acoustic sensors play an important role in many areas, such as homeland security, navigation, communication, health care and industry. However, the fundamental pressure detection limit hinders the performance of current acoustic sensing technologies. Here, through analytical, numerical and experimental studies, we show that anisotropic acoustic metamaterials can be designed to have strong wave compression effect that renders direct amplification of pressure fields in metamaterials. This enables a sensing mechanism that can help overcome the detection limit of conventional acoustic sensing systems. We further demonstrate a metamaterial-enhanced acoustic sensing system that achieves more than 20 dB signal-to-noise enhancement (over an order of magnitude enhancement in detection limit). With this system, weak acoustic pulse signals overwhelmed by the noise are successfully recovered. This work opens up new vistas for the development of metamaterial-based acoustic sensors with improved performance and functionalities that are highly desirable for many applications. PMID:25316410

  6. Enhancing gas-phase reaction in a plasma using high intensity and high power ultrasonic acoustic waves

    2010-01-01

    acoustic energy by at least one ultrasonic high intensity and high power gas-jet acoustic wave generator (101), where said ultrasonic high intensity and high power acoustic waves are directed to propagate towards said plasma (104) so that at least a part of said predetermined amount of acoustic energy is......This invention relates to enhancing a gas-phase reaction in a plasma comprising: creating plasma (104) by at least one plasma source (106), and wherein that the method further comprises: generating ultrasonic high intensity and high power acoustic waves (102) having a predetermined amount of...... absorbed into said plasma (104), and where a sound pressure level of said generated ultrasonic high intensity and high power acoustic waves (102) is at least substantially 140 dB and where an acoustic power of said generated ultrasonic high intensity and high power acoustic waves (102); is at least...

  7. Bifurcations of nonlinear ion-acoustic travelling waves in a multicomponent magnetoplasma with superthermal electrons

    Selim, M. M.; El-Depsy, A.; El-Shamy, E. F.

    2015-12-01

    Properties of nonlinear ion-acoustic travelling waves propagating in a three-dimensional multicomponent magnetoplasma system composed of positive ions, negative ions and superthermal electrons are considered. Using the reductive perturbation technique (RPT), the Zkharov-Kuznetsov (ZK) equation is derived. The bifurcation theory of planar dynamical systems is applied to investigate the existence of the solitary wave solutions and the periodic travelling wave solutions of the resulting ZK equation. It is found that both compressive and rarefactive nonlinear ion-acoustic travelling waves strongly depend on the external magnetic field, the unperturbed positive-to-negative ions density ratio, the direction cosine of the wave propagation vector with the Cartesian coordinates, as well as the superthermal electron parameter. The present model may be useful for describing the formation of nonlinear ion-acoustic travelling wave in certain astrophysical scenarios, such as the D and F-regions of the Earth's ionosphere.

  8. PASSIVE WIRELESS MULTI-SENSOR TEMPERATURE AND PRESSURE SENSING SYSTEM USING ACOUSTIC WAVE DEVICES Project

    National Aeronautics and Space Administration — This proposal describes the development of passive surface acoustic wave (SAW) sensors and multi-sensor systems for NASA application to remote wireless sensing of...

  9. Passive Wireless Cryogenic Liquid Level Sensors Using Orthogonal Frequency Coded Acoustic Wave Devices Project

    National Aeronautics and Space Administration — This proposal describes the development of passive wireless surface acoustic wave (SAW) based liquid level sensors for NASA application to cryogenic liquid level...

  10. Passive Wireless Multi-Sensor Temperature and Pressure Sensing System Using Acoustic Wave Devices Project

    National Aeronautics and Space Administration — This proposal describes the continued development of passive, orthogonal frequency coded (OFC) surface acoustic wave (SAW) sensors and multi-sensor systems, an...

  11. Large amplitude Langmuir and ion-acoustic waves in a relativistic two-fluid plasma

    Large amplitude Langmuir and ion-acoustic waves in a relativistic two-fluid plasma are analysed by the pseudo-potential method. The existence conditions for relativistic nonlinear Langmuir waves depend on the relativistic effect, the particular energy and the ion mass to electron mass ratio. The allowable range of the normalized potential depends on the relativistic effect. It is shown that the Mach number has the significant effect for the formation of relativistic nonlinear ion-acoustic waves rather than the ratio of the ion-acoustic velocity to the velocity of light. The allowable range of the normalized potential depends on the Mach number. The present investigation predicts new findings of relativistic nonlinear Langmuir and ion-acoustic waves in plasmas in which high-speed electrons and ions coexist. (author)

  12. Characterization of wave physics in acoustic metamaterials using a fiber optic point detector

    Ganye, Randy; Chen, Yongyao; Liu, Haijun; Bae, Hyungdae; Wen, Zhongshan; Yu, Miao

    2016-06-01

    Due to limitations of conventional acoustic probes, full spatial field mapping (both internal and external wave amplitude and phase measurements) in acoustic metamaterials with deep subwavelength structures has not yet been demonstrated. Therefore, many fundamental wave propagation phenomena in acoustic metamaterials remain experimentally unexplored. In this work, we realized a miniature fiber optic acoustic point detector that is capable of omnidirectional detection of complex spatial acoustic fields in various metamaterial structures over a broadband spectrum. By using this probe, we experimentally characterized the wave-structure interactions in an anisotropic metamaterial waveguide. We further demonstrated that the spatial mapping of both internal and external acoustic fields of metamaterial structures can help obtain important wave propagation properties associated with material dispersion and field confinement, and develop an in-depth understanding of the waveguiding physics in metamaterials. The insights and inspirations gained from our experimental studies are valuable not only for the advancement of fundamental metamaterial wave physics but also for the development of functional metamaterial devices such as acoustic lenses, waveguides, and sensors.

  13. Mesospheric, Thermospheric, and Ionospheric Responses to Acoustic and Gravity Waves Generated by Transient Forcing

    Snively, J. B.; Zettergren, M. D.

    2014-12-01

    Strong acoustic waves with periods ~1-4 minutes have been confirmed to perturb the ionosphere following their generation by earthquakes [e.g., Garcia et al., GRL, 40(5), 2013] and volcanic eruption events [e.g., Heki, GRL, 33, L14303, 2006]. Clear acoustic and gravity wave signatures have also been reported in ionospheric data above strong tropospheric convection [Nishioka, GRL, 40(21), 2013], and prior modeling results suggest that convectively-generated acoustic waves with ~3-4 minute periods are readily detectable above their sources in TEC [Zettergren and Snively, GRL, 40(20), 2013]. These observations have provided quantitative insight into the coupling of processes occurring near Earth's surface with the upper atmosphere and ionosphere over short time-scales. Here, we investigate acoustic waves and short-period gravity waves generated by sources near ground level, and the observable responses of the mesosphere, lower-thermosphere, and ionosphere (MLTI) systems. Numerical simulations are performed using a nonlinear, compressible, atmospheric dynamics model, in cylindrically-axisymmetric coordinates, to investigate wave generation, upward propagation, steepening, and dissipation. Acoustic waves may produce observable signatures in the mesospheric hydroxyl airglow layer [e.g., Snively, GRL, 40(17), 2013], and can strongly perturb the lower-thermosphere and E- and F-region ionosphere, prior to the arrival of simultaneously-generated gravity waves. Using a coupled multi-fluid ionospheric model [Zettergren and Semeter, JGR, 117(A6), 2012], extended for mid and low latitudes using a 2D dipole magnetic field coordinate system [Zettergren and Snively, GRL, 40(20), 2013], we investigate its response to realistic acoustic wave perturbations. In particular, we demonstrate that the MLT and ionospheric responses are significantly and nonlinearly determined by the acoustic wave source geometry, spectrum, and amplitude, in addition to the local ambient state of the

  14. A method of acoustic wave registration and determination their generation region

    Here is presented a method of acoustic wave registration with using of a synchronous LF broadcasting system. This method of detection and determination of underground nuclear explosion location is based on a registration of ionospheric disturbances induced by acoustic waves at the region of LF sign al reflection. The measuring complex created in the institute of the Ionosphere /1/ allows to register amplitude-frequency characteristics of composite signal from synchronous broadcasting net

  15. Laser-induced acoustic wave generation/propagation/interaction in water in various internal channels

    Ko, Seung Hwan; Lee, Daeho; Pan, Heng; Ryu, Sang-Gil; Grigoropoulos, Costas P.; Kladias, Nick; Panides, Elias; Domoto, Gerald A.

    2010-01-01

    Short pulsed laser-induced single acoustic wave generation, propagation, interaction within a water-filled internal channel are experimentally and numerically studied. A large-area, short-duration, single-plane acoustic wave was generated by the thermoelastic interaction of a homogenized nanosecond pulsed laser beam with a liquid–solid interface and propagated at the speed of sound in water. Laser flash Schlieren photography was used to visualize the transient interaction of the plane acousti...

  16. Dust-Acoustic Waves in Strongly Coupled Dusty Plasmas Containing Variable-Charge Impurities

    XIE Bai-Song; HE Kai-Fen; M. Y. Yu

    2000-01-01

    A relatively self-consistent theory of dust-acoustic waves in the strongly coupled dusty plasmas containing variable charge impurities is given. Relevant physical processes such as dust elastic relaxation and dust charge relaxation are taken into account. It is shown that the negative dispersion of dust-acoustic waves due to the strong correlation of dusts is enhanced in the presence of dust-neutral collisions.

  17. Surface-Plasmon-Polariton (SPP)-Like Acoustic Surface Waves on Elastic Metamaterials

    Deng, Ke; He, Zhaojian; Ding, Yiqun; Zhao, Heping; Liu, Zhengyou

    2014-01-01

    We investigate the dispersion properties of the acoustic surface waves on surface of elastic metamaterials. With an analytical approach, we show that unconventional acoustic surface waves, with dispersion behaviors very similar to the electromagnetic surface plasmon polaritons (SPPs) on metal surfaces, can exist on the elastic metamaterials around the frequency at which the elastic Lam\\'e's constants satisfy lambda+mu=0. Two typical elastic metamaterials are exemplified to demonstrate such pe...

  18. Prediction and near-field observation of skull-guided acoustic waves

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2016-01-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field properties unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoaco...

  19. On the wave equation with semilinear porous acoustic boundary conditions

    Graber, Philip Jameson

    2012-05-01

    The goal of this work is to study a model of the wave equation with semilinear porous acoustic boundary conditions with nonlinear boundary/interior sources and a nonlinear boundary/interior damping. First, applying the nonlinear semigroup theory, we show the existence and uniqueness of local in time solutions. The main difficulty in proving the local existence result is that the Neumann boundary conditions experience loss of regularity due to boundary sources. Using an approximation method involving truncated sources and adapting the ideas in Lasiecka and Tataru (1993) [28], we show that the existence of solutions can still be obtained. Second, we prove that under some restrictions on the source terms, then the local solution can be extended to be global in time. In addition, it has been shown that the decay rates of the solution are given implicitly as solutions to a first order ODE and depends on the behavior of the damping terms. In several situations, the obtained ODE can be easily solved and the decay rates can be given explicitly. Third, we show that under some restrictions on the initial data and if the interior source dominates the interior damping term and if the boundary source dominates the boundary damping, then the solution ceases to exists and blows up in finite time. Moreover, in either the absence of the interior source or the boundary source, then we prove that the solution is unbounded and grows as an exponential function. © 2012 Elsevier Inc.

  20. Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.

    Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R

    2012-08-01

    Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis. PMID:22742654

  1. Acoustic Wave Velocity as a Selection Trait in Eucalyptus nitens

    David Blackburn

    2014-04-01

    Full Text Available Previous studies in Eucalyptus nitens have revealed favourable genetic correlations exist between acoustic wave velocity (AWV in standing trees and modulus of elasticity (MOE, which can determine the suitability of trees for structural timber and/or engineered wood products. This study investigates the strength and stability of genetic variation in standing tree AWV across a range of environments in Tasmania, where there are a number of large plantation estates and breeding trials. Trees under study were from open-pollinated progeny trials established in 1993. Across sites, for standing tree AWV the ranking of E. nitens races did not change and within-race additive genetic correlations were strong (0.61 to 0.99. Heritabilities (0.16 to 0.74 and coefficients of additive genetic variation (2.6 to 4.8 were moderate for this trait. Correlations between standing tree AWV and both basic density and diameter at breast height (DBH were favourable. Results indicate that there is potential to improve MOE in E. nitens through the exploitation of genetic variation in AWV among and within races, the expression of genetic variation in AWV is relatively stable across different growing environments, and past selection for basic density and growth in pulpwood breeding programs is unlikely to have adversely affected MOE.

  2. Propagation and localization of acoustic waves in Fibonacci phononic circuits

    Aynaou, H [Laboratoire de Dynamique et d' Optique des Materiaux, Departement de Physique, Faculte des Sciences, Universite Mohamed Premier, 60000 Oujda (Morocco); Boudouti, E H El [Laboratoire de Dynamique et d' Optique des Materiaux, Departement de Physique, Faculte des Sciences, Universite Mohamed Premier, 60000 Oujda (Morocco); Djafari-Rouhani, B [Laboratoire de Dynamique et Structure des Materiaux Moleculaires, UMR CNRS 8024, UFR de Physique, Universite de Lille 1, F-59655 Villeneuve d' Ascq (France); Akjouj, A [Laboratoire de Dynamique et Structure des Materiaux Moleculaires, UMR CNRS 8024, UFR de Physique, Universite de Lille 1, F-59655 Villeneuve d' Ascq (France); Velasco, V R [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)

    2005-07-13

    A theoretical investigation is made of acoustic wave propagation in one-dimensional phononic bandgap structures made of slender tube loops pasted together with slender tubes of finite length according to a Fibonacci sequence. The band structure and transmission spectrum is studied for two particular cases. (i) Symmetric loop structures, which are shown to be equivalent to diameter-modulated slender tubes. In this case, it is found that besides the existence of extended and forbidden modes, some narrow frequency bands appear in the transmission spectra inside the gaps as defect modes. The spatial localization of the modes lying in the middle of the bands and at their edges is examined by means of the local density of states. The dependence of the bandgap structure on the slender tube diameters is presented. An analysis of the transmission phase time enables us to derive the group velocity as well as the density of states in these structures. In particular, the stop bands (localized modes) may give rise to unusual (strong normal) dispersion in the gaps, yielding fast (slow) group velocities above (below) the speed of sound. (ii) Asymmetric tube loop structures, where the loops play the role of resonators that may introduce transmission zeros and hence new gaps unnoticed in the case of simple diameter-modulated slender tubes. The Fibonacci scaling property has been checked for both cases (i) and (ii), and it holds for a periodicity of three or six depending on the nature of the substrates surrounding the structure.

  3. Starch viscoelastic properties studied with an acoustic wave sensor.

    Santos, M D; Gomes, M T S R

    2014-01-01

    Gelatinization and retrogradation of starch was followed in real time with an acoustic wave sensor. This study relies on the monitorization of the frequency of oscillation of a piezoelectric quartz crystal in contact with a 2.5% emulsion of a commercial maize starch, during heating and cooling. The technique showed to be very powerful and sensitive to most of the changes described in the literature, which have been elucidated by some other techniques. The value for the temperature of gelatinization found using the sensor was confirmed by the analysis of the same starch emulsion by polarized light microscopy. Temperatures of gelatinization were found to vary with the sample heating rate, as follows: 73.5 °C at 2.0 °C/min, 66.0 °C at 1.0 °C/min, and 65.0 °C at 0.5 °C/min. Hysteresis of the studied system was evidenced by the frequency shift before heating and after cooling till the initial temperature. Analysis performed on a 1.5% emulsion of a rice starch heated at 2.0 °C/min and cooled as before, evidenced no hysteresis and showed complete reversibility, in which concerns to the series frequency of the piezoelectric quartz crystal. PMID:24274480

  4. Acoustic wave propagation in fluids with coupled chemical reactions

    This investigation presents a hydroacoustic theory which accounts for sound absorption and dispersion in a multicomponent mixture of reacting fluids (assuming a set of first-order acoustic equations without diffusion) such that several coupled reactions can occur simultaneously. General results are obtained in the form of a biquadratic characteristic equation (called the Kirchhoff-Langevin equation) for the complex propagation variable chi = - (α + iω/c) in which α is the attenuation coefficient, c is the phase speed of the progressive wave and ω is the angular frequency. Computer simulations of sound absorption spectra have been made for three different chemical systems, each comprised of two-step chemical reactions using physico-chemical data available in the literature. The chemical systems studied include: (1) water-dioxane, (2) aqueous solutions of glycine and (3) cobalt polyphosphate mixtures. Explicit comparisons are made between the exact biquadratic characteristic solution and the approximate equation (sometimes referred to as a Debye equation) previously applied to interpret the experimental data for the chemical reaction contribution to the absorption versus frequency. The relative chemical reaction and classical viscothermal contributions to the sound absorption are also presented. Several discrepancies that can arise when estimating thermodynamic data (chemical reaction heats or volume changes) for multistep chemical reaction systems when making dilute solution or constant density assumptions are discussed

  5. Surface Acoustic Wave (SAW Resonators for Monitoring Conditioning Film Formation

    Siegfried Hohmann

    2015-05-01

    Full Text Available We propose surface acoustic wave (SAW resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM sensor measurements, which confirmed the suitability of the SAW resonators for this application.

  6. Dust ion acoustic solitary waves in a collisional dusty plasma with dust grains having Gaussian distribution

    The influence of dust size distribution on the dust ion acoustic solitary waves in a collisional dusty plasma is investigated. It is found that dust size distribution changes the amplitude and width of a solitary wave. A critical wave number is derived for the existence of purely damping mode. A deformed Korteweg-de Vries (dKdV) equation is obtained for the propagation of weakly nonlinear dust ion acoustic solitary waves and the effect of different plasma parameters on the solution of this equation is also presented

  7. Propagation of flexural waves in inhomogeneous plates exhibiting hysteretic nonlinearity: Nonlinear acoustic black holes.

    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. PMID:25937493

  8. Einstein-de Broglie relations for wave packet: the acoustic world

    Simaciu, Ion; Dumitrescu, Gheorghe; Georgeta, Nan

    2015-01-01

    In this paper we study the relations of Einstein-de Broglie type for the wave packets. We assume that the wave packet is a possible model of particle . When studying the behaviour of the wave packet for standing waves, in relation to an accelerated observer (i.e. Rindler observer), there can be demonstrated that the equivalent mass of the packet is the inertial mass. In our scenario, the waves and of the wave packets are depicted by the strain induced/produced in the medium. The properties of the waves, of the wave packet and, generally, of the perturbations in a material medium suggest the existence of an acoustic world. The acoustic world has mechanical and thermodynamical properties. The perturbations that are generated and propagated in the medium are correlated by means of acoustic waves with maximum speed. The observers of this world of disturbances (namely the acoustic world) have senses that are based on the perception of mechanical waves (disturbance of any kind) and apparatus for detecting and acqui...

  9. Mesospheric airglow and ionospheric responses to upward-propagating acoustic and gravity waves above tropospheric sources

    Snively, J. B.; Zettergren, M. D.

    2013-12-01

    The existence of acoustic waves (periods ~1-5 minutes) and gravity waves (periods >4 minutes) in the ionosphere above active tropospheric convection has been appreciated for more than forty years [e.g., Georges, Rev. Geophys. and Space Phys., 11(3), 1973]. Likewise, gravity waves exhibiting cylindrical symmetry and curvature of phase fronts have been observed via imaging of the mesospheric airglow layers [e.g., Yue et al., JGR, 118(8), 2013], clearly associated with tropospheric convection; gravity wave signatures have also recently been detected above convection in ionospheric total electron content (TEC) measurements [Lay et al., GRL, 40, 2013]. We here investigate the observable features of acoustic waves, and their relationship to upward-propagating gravity waves generated by the same sources, as they arrive in the mesosphere, lower-thermosphere, and ionosphere (MLTI). Numerical simulations using a nonlinear, cylindrically-axisymmetric, compressible atmospheric dynamics model confirm that acoustic waves generated by transient tropospheric sources may produce "concentric ring" signatures in the mesospheric hydroxyl airglow layer that precede the arrival of gravity waves. As amplitudes increase with altitude and decreasing neutral density, the modeled acoustic waves achieve temperature and vertical wind perturbations on the order of ~10s of Kelvin and m/s throughout the E- and F-region. Using a coupled multi-fluid ionospheric model [Zettergren and Semeter, JGR, 117(A6), 2012], extended for low-latitudes using a 2D dipole magnetic field coordinate system, we investigate acoustic wave perturbations to the ionosphere in the meridional direction. Resulting perturbations are predicted to be detectable by ground-based radar and GPS TEC measurements, or via in situ instrumentation. Although transient and short-lived, the acoustic waves' airglow and ionospheric signatures are likely to in some cases be observable, and may provide important insight into the regional

  10. Droplets displacement and oscillations induced by ultrasonic surface acoustic waves: a quantitative study

    Brunet, P.; Baudoin, M; Matar, O. Bou; Zoueshtiagh, F.

    2010-01-01

    We present an experimental study of a droplet interacting with an ultrasonic surface acoustic wave (SAW). Depending on the amplitude of the wave, the drop can either experience an internal flow with its contact-line pinned, or (at higher amplitude) move along the direction of the wave also with internal flow. Both situations appear together with oscillations of the drop free-surface. The physical origins of the internal mixing flow as well as the drop displacement and surface waves are still ...

  11. On Mass Loading and Dissipation Measured with Acoustic Wave Sensors: A Review

    Marina V. Voinova

    2009-01-01

    Full Text Available We summarize current trends in the analysis of physical properties (surface mass density, viscosity, elasticity, friction, and charge of various thin films measured with a solid-state sensor oscillating in a gaseous or liquid environment. We cover three different types of mechanically oscillating sensors: the quartz crystal microbalance with dissipation (QCM-D monitoring, surface acoustic wave (SAW, resonators and magnetoelastic sensors (MESs. The fourth class of novel acoustic wave (AW mass sensors, namely thin-film bulk acoustic resonators (TFBARs on vibrating membranes is discussed in brief. The paper contains a survey of theoretical results and practical applications of the sensors and includes a comprehensive bibliography.

  12. Symmetrical and anti-symmetrical coherent perfect absorption for acoustic waves

    We investigate tunable acoustic absorption enabled by the coherent control of input waves. It relies on coherent perfect absorption originally proposed in optics. By designing appropriate acoustic metamaterial structures with resonating effective bulk modulus or density, we show that complete absorption of incident waves impinging on the metamaterial can be achieved for either symmetrical or anti-symmetrical inputs in the forward and backward directions. By adjusting the relative phase between the two incident beams, absorption can be tuned effectively from unity to zero, making coherent control useful in applications like acoustic modulators, noise controllers, transducers, and switches

  13. Ion-acoustic solitary waves and spectrally uniform scattering cross section enhancements

    J. Ekeberg; Wannberg, G.; Eliasson, L; Stasiewicz, K.

    2010-01-01

    Spectra measured by incoherent scatter radars are formed predominantly by scattering of the incident signal off ion-acoustic and Langmuir waves in the ionosphere. Occasionally, the upshifted and/or downshifted lines produced by the ion-acoustic waves are enhanced well above thermal levels and referred to as naturally enhanced ion-acoustic lines. In this paper, we study another kind of enhancement, which is spectrally uniform over the whole ion-line, i.e. the up- and downshifted shoulder and t...

  14. Topology optimization applied to room acoustic problems and surface acoustic wave devices

    Dühring, Maria Bayard; Sigmund, Ole; Jensen, Jakob Søndergaard;

    engineering fields such as mechanism design, fluid problems and photonic and phononic band-gap materials and structures [1,2]. In this project topology optimization is first applied to control acoustic properties in a room [3]. It is shown how the squared sound pressure amplitude in a certain part of a room...... can be minimized either by distribution of reflecting material in a design domain along the ceiling or by distribution of absorbing and reflecting material along all the walls for both 2D and 3D problems. It is also shown how the method can be used to design sound barriers. The main part of the...... shape of the frequency response. To begin with, a 2D model of a Mach-Zehnder interferometer impacted by a SAW is considered and a parameter study of the geometry to get the biggest modulation of the light waves in the interferometer arms is performed. Then a 2D filter is modeled and optimized such that...

  15. Anisotropic metamaterials for full control of acoustic waves.

    Christensen, Johan; García de Abajo, F Javier

    2012-03-23

    We study a class of acoustic metamaterials formed by layers of perforated plates and producing negative refraction and backward propagation of sound. A slab of such material is shown to act as a perfect acoustic lens, yielding images with subwavelength resolution over large distances. Our study constitutes a nontrivial extension of similar concepts from optics to acoustics, capable of sustaining negative refraction over extended angular ranges, with potential application to enhanced imaging for medical and detection purposes, acoustofluidics, and sonochemistry. PMID:22540586

  16. A study on dust acoustic traveling wave solutions and quasiperiodic route to chaos in nonthermal magnetoplasmas

    Saha, Asit; Pal, Nikhil; Saha, Tapash; Ghorui, M. K.; Chatterjee, Prasanta

    2016-06-01

    Bifurcations and chaotic behaviors of dust acoustic traveling waves in magnetoplasmas with nonthermal ions featuring Cairns-Tsallis distribution is investigated on the framework of the further modified Kadomtsev-Petviashili (FMKP) equation. The FMKP equation is derived employing the reductive perturbation technique (RPT). Bifurcations of dust acoustic traveling waves of the FMKP equation is presented. Using the bifurcation theory of planar dynamical systems, two new analytical traveling wave solutions for solitary and periodic waves are derived depending on the parameters α , α _1, q, l and U. Considering an external periodic perturbation, the chaotic behavior of dust acoustic traveling waves is investigated through quasiperiodic route to chaos. The parameter q significantly affects the chaotic behavior of the perturbed FMKP equation.

  17. Surface acoustic wave-induced precise particle manipulation in a trapezoidal glass microfluidic channel

    Surface acoustic wave (SAW) excitation of an acoustic field in a trapezoidal glass microfluidic channel for particle manipulation in continuous flow has been demonstrated. A unidirectional interdigital transducer (IDT) on a Y-cut Z-propagation lithium niobate (LiNbO3) substrate was used to excite a surface acoustic wave at approximately 35 MHz. An SU8 layer was used for adhesive bonding of the superstrate glass layer and the substrate piezoelectric layer. This work extends the use of SAWs for acoustic manipulation to also include glass channels in addition to prior work with mainly poly-di-methyl-siloxane channels. Efficient alignment of 1.9 µm polystyrene particles to narrow nodal regions was successfully demonstrated. In addition, particle alignment with only one IDT active was realized. A finite element method simulation was used to visualize the acoustic field generated in the channel and the possibility of 2D alignment into small nodal regions was demonstrated

  18. Experimental verification of theoretical equations for acoustic radiation force on compressible spherical particles in traveling waves

    Johnson, Kennita A.; Vormohr, Hannah R.; Doinikov, Alexander A.; Bouakaz, Ayache; Shields, C. Wyatt; López, Gabriel P.; Dayton, Paul A.

    2016-05-01

    Acoustophoresis uses acoustic radiation force to remotely manipulate particles suspended in a host fluid for many scientific, technological, and medical applications, such as acoustic levitation, acoustic coagulation, contrast ultrasound imaging, ultrasound-assisted drug delivery, etc. To estimate the magnitude of acoustic radiation forces, equations derived for an inviscid host fluid are commonly used. However, there are theoretical predictions that, in the case of a traveling wave, viscous effects can dramatically change the magnitude of acoustic radiation forces, which make the equations obtained for an inviscid host fluid invalid for proper estimation of acoustic radiation forces. To date, experimental verification of these predictions has not been published. Experimental measurements of viscous effects on acoustic radiation forces in a traveling wave were conducted using a confocal optical and acoustic system and values were compared with available theories. Our results show that, even in a low-viscosity fluid such as water, the magnitude of acoustic radiation forces is increased manyfold by viscous effects in comparison with what follows from the equations derived for an inviscid fluid.

  19. Characteristics and realization of the second generation surface acoustic wave's wavelet device

    Wen Changbao; Zhu Changchun; Lu Wenke; Liu Qinghong; Liu Junhua

    2006-01-01

    To overcome the bulk acoustic wave (BAW), the triple transit signals and the discontinuous frequency band in the first generation surface acoustic wave's (FGSAW's) wavelet device, the full transfer multistrip coupler (MSC) is applied to implement wavelet device, and a novel structure of the second generation surface acoustic wave's (SGSAW's) wavelet device is proposed. In the SGSAW's wavelet device, the BAW is separated and eliminated in different acoustic propagating tracks, and the triple transit signal is suppressed. For arbitrary wavelet scale device, the center frequency is three times the radius of frequency band, which ensures that the frequency band of the SGSAW's wavelet device is continuous, and avoids losing signals caused by the discontinuation of frequency band. Experimental result confirms that the BAW suppression, ripples in band, receiving loss and insertion loss of the SGSAW's wavelet device are remarkably improved compared with those of the FGSAW's wavelet device.

  20. Dependence of oscillational instabilities on the amplitude of the acoustic wave in single-axis levitators

    Orozco-Santillán, Arturo; Ruiz-Boullosa, Ricardo; Cutanda Henríquez, Vicente;

    2007-01-01

    It is well known that acoustic waves exert forces on a boundary with which they interact; these forces can be so intense that they can compensate for the weight of small objects up to a few grams. In this way, it is possible to maintain solid or liquid samples levitating in a fluid, avoiding...... the use of containers, which may be undesirable for certain applications. Moreover, small samples can be manipulated by means of acoustic waves. In this paper, we report a study on the oscillational instabilities that can appear on a levitated solid sphere in single-axis acoustic devices. A theory...... proportional to the oscillation frequency of the levitated sample. We also present experimental results that show that the oscillational instabilities can be reduced if the amplitude of the acoustic wave is increased; as a result, stable conditions can be obtained where the oscillations of the sphere...

  1. Miniature inhalation therapy platform using surface acoustic wave microfluidic atomization.

    Qi, Aisha; Friend, James R; Yeo, Leslie Y; Morton, David A V; McIntosh, Michelle P; Spiccia, Leone

    2009-08-01

    Pulmonary drug administration requires direct delivery of drug formulations into the lower pulmonary tract and alveoli of the lung in the form of inhaled particles or droplets, providing a distinct advantage over other methods for the treatment of respiratory diseases: the drug can be delivered directly to the site of inflammation, thus reducing the need for systemic exposure and the possibility of adverse effects. However, it is difficult to produce droplets of a drug solution within a narrow monodisperse size range (1-10 microm) needed for deposition in the lower pulmonary tract and alveoli. Here, we demonstrate the use of surface acoustic wave microfluidic atomization as an efficient means to generate appropriate aerosols containing a model drug, the short-acting beta2 agonist salbutamol, for the treatment of asthma. The mean aerosol diameter produced, 2.84+/-0.14 microm, lies well within the optimum size range, confirmed by a twin-stage impinger lung model, demonstrating that approximately 70 to 80% of the drug supplied to the atomizer is deposited within the lung. Our preliminary study explores how to control the aerosol diameter and lung delivery efficiency through the surface tension, viscosity, and input power, and also indicates which factors are irrelevant-like the fluid density. Even over a modest power range of 1-1.5 W, SAW atomization provides a viable and efficient generic nebulization platform for the delivery of drugs via the pulmonary route for the treatment of various diseases. The control offered over the aerosol size, low power requirements, high delivery efficiency, and the miniaturization of the system together suggest the proposed platform represents an attractive alternative to current nebulizers compatible with microfluidic technologies. PMID:19606295

  2. Effect of nonthermal ion distribution and dust temperature on nonlinear dust-acoustic solitary waves

    K Annou; R Annou

    2012-01-01

    Dust-acoustic solitary waves in unmagnetized dusty plasma whose constituents are inertial charged dust grains, Boltzmannian electrons and nonthermal ions have been investigated by taking into account finite dust temperature. The pseudopotential has been used to study solitary solution. The existence of solitary waves having negative potential is reported.

  3. Finite element analysis of surface acoustic waves in high aspect ratio electrodes

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2008-01-01

    This paper elaborates on how the finite element method is employed to model surface acoustic waves generated by high aspect ratio electrodes and their interaction with optical waves in a waveguide. With a periodic model it is shown that these electrodes act as a mechanical resonator which slows...

  4. Propagation of Ion-Acoustic Wave in an Inhomogeneous Dusty Plasma with. Dust Charge Fluctuation

    LI Jing-Ju; XIAO De-Long; LI Yang-Fang; MA Jin-Xiu

    2007-01-01

    @@ The propagation of dust ion-acoustic wave in an inhomogeneous dusty plasma is studied by taking the dust charge fluctuation and collisions into account. It is shown that the dust charge fluctuation brings a phase shift to the wave. Furthermore, because of the presence of dust charge fluctuation, a new damping term rises, which makes the damping more sharply.

  5. Lagrangean description of nonlinear dust--ion acoustic waves in dusty plasmas

    Kourakis, I.; Shukla, P.K.

    2004-01-01

    An analytical model is presented for the description of nonlinear dust-ion-acoustic waves propagating in an unmagnetized, collisionless, three component plasma composed of electrons, ions and inertial dust grains. The formulation relies on a Lagrangean approach of the plasma fluid model. The modulational stability of the wave amplitude is investigated. Different types of localized envelope electrostatic excitations are shown to exist.

  6. Ion acoustic waves in a positive ion-negative ion plasma

    Experimentally observed wave profiles of ion acoustic waves in a dispersive positive ion-negative ion plasma, reported in the literature, are compared with those theoretically derived ones. The possibility of physical applications for plasma diagnosis is suggested. (author). 3 refs, 3 figs

  7. The first radial-mode Lorentzian Landau damping of dust acoustic space-charge waves

    Lee, Myoung-Jae; Jung, Young-Dae

    2016-05-01

    The dispersion properties and the first radial-mode Lorentzian Landau damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau damping rate of the dust acoustic space-charge wave is derived in a cylindrical waveguide dusty plasma. The damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau damping rate due to the nonthermal character and geometric effects are also discussed.

  8. Eulerian Simulation of Acoustic Waves Over Long Range in Realistic Environments

    Chitta, Subhashini; Steinhoff, John

    2015-11-01

    In this paper, we describe a new method for computation of long-range acoustics. The approach is a hybrid of near and far-field methods, and is unique in its Eulerian treatment of the far-field propagation. The near-field generated by any existing method to project an acoustic solution onto a spherical surface that surrounds a source. The acoustic field on this source surface is then extended to an arbitrarily large distance in an inhomogeneous far-field. This would normally require an Eulerian solution of the wave equation. However, conventional Eulerian methods have prohibitive grid requirements. This problem is overcome by using a new method, ``Wave Confinement'' (WC) that propagates wave-identifying phase fronts as nonlinear solitary waves that live on grid indefinitely. This involves modification of wave equation by the addition of a nonlinear term without changing the basic conservation properties of the equation. These solitary waves can then be used to ``carry'' the essential integrals of the acoustic wave. For example, arrival time, centroid position and other properties that are invariant as the wave passes a grid point. Because of this property the grid can be made as coarse as necessary, consistent with overall accuracy to resolve atmospheric/ground variations. This work is being funded by the U.S. Army under a Small Business Innovation Research (SBIR) program (contract number: # W911W6-12-C-0036). The authors would like to thank Dr. Frank Caradonna and Dr. Ben W. Sim for this support.

  9. Amplification of surface acoustic waves by transverse electric current in piezoelectric semiconductors

    Gulyaev, Yuri V.

    1974-01-01

    It is shown that the principal characteristic feature of the surface acoustic waves in piezoelectrics—the presence of an alternating electric field transverse to the surface, which can be of the same order of magnitude as the longitudinal field—may not only give rise to the known transverse...... acoustoelectric effect but also lead to amplification of surface acoustic waves by electron drift perpendicular to the surface. For Love waves in a piezoelectric semiconductor film on a highly conducting substrate, the amplification coefficient is found and the conditions necessary for amplification...

  10. Excitation of Light-Induced Acoustic Waves in Doped Lithium Niobate Crystals

    2006-01-01

    The phenomena of acoustic emission in doped lithium niobate crystals were observed in the process of light-induced quasi-breakdown. It is found that the ultrasonic waves introduce into the crystal have been modulated by the low frequency acoustic waves. Its frequency increases with the rise of the intensity of incident light and its jump period of breakdown is the same as that of the photovoltaic current Ic, the change of light-induced refractive index Δn and the diffracted light intensity L. This effect was explained with the interaction of the three waves and resonant state theory. The experimental results and the theoretical analysis are in conformity.

  11. Mesospheric hydroxyl airglow signatures of acoustic and gravity waves generated by transient tropospheric forcing

    Snively, J. B.

    2013-09-01

    Numerical model results demonstrate that acoustic waves generated by tropospheric sources may produce cylindrical "concentric ring" signatures in the mesospheric hydroxyl airglow layer. They may arrive as precursors to upward propagating gravity waves, generated simultaneously by the same sources, and produce strong temperature perturbations in the thermosphere above. Transient and short-lived, the acoustic wave airglow intensity and temperature signatures are predicted to be detectable by ground-based airglow imaging systems and may provide new insight into the forcing of the upper atmosphere from below.

  12. Analytical Study of Nonlinear Dust Acoustic Waves in Two-Dimensional Dust Plasma with Dust Charge Variation

    LIN Chang; ZHANG Xiu-Lian

    2005-01-01

    The nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation is analytically investigated by using the formally variable separation approach. New analytical solutions for the governing equation of this system have been obtained for dust acoustic waves in a dust plasma for the first time. We derive exact analytical expressions for the general case of the nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation.

  13. Total transmission and total reflection of acoustic wave by zero index metamaterials loaded with general solid defects

    Wang, Ziyu; Yang, Fan; Liu, Libing; Kang, Ming; Liu, Fengming

    2013-01-01

    This work investigates acoustic wave transmission property through a zero index metamaterials (ZIM) waveguide embedded with a general solid defect. Total transmission and total reflection can be achieved by adjusting the parameters of the solid defect. We comprehensively study how longitudinal/transverse wave speeds of the solid defect affect the acoustic wave propagation through the waveguide. A two-dimensional (2D) acoustic crystals (ACs) system with zero index is used to realize these intr...

  14. A Four-Quadrant PVDF Transducer for Surface Acoustic Wave Detection

    Zhi Chen

    2012-08-01

    Full Text Available In this paper, a polyvinylidene fluoride (PVDF piezoelectric transducer was developed to detect laser-induced surface acoustic waves in a SiO2-thin film–Si-substrate structure. In order to solve the problems related to, firstly, the position of the probe, and secondly, the fact that signals at different points cannot be detected simultaneously during the detection process, a four-quadrant surface acoustic wave PVDF transducer was designed and constructed for the purpose of detecting surface acoustic waves excited by a pulse laser line source. The experimental results of the four-quadrant piezoelectric detection in comparison with the commercial nanoindentation technology were consistent, the relative error is 0.56%, and the system eliminates the piezoelectric surface wave detection direction deviation errors, improves the accuracy of the testing system by 1.30%, achieving the acquisition at the same time at different testing positions of the sample.

  15. Modulational instability of electromagnetic ion-cyclotron waves by ion acoustic waves in a collisionless plasma

    Using the hydrodynamic model for a homogeneous plasma, we have investigated the modulational instability of an electromagnetic ion-cyclotron wave by a low-frequency electrostatic ion acoustic mode in a collisionless plasma. The low-frequency nonlinearity of the instability arises through the parallel ponderomotive force on the ions, and the high-frequency nonlinearity arises through the nonlinear current densities of the ions. For typical plasma parameters n00 = 1013 cm-3, ω/sub c/i/ω0 = 1.2, B/sub s/ = 10 kG, T/sub i/ = 1 keV, T/sub i/ = 0.05 keV, and theta = 300, the growth rate of the instability turns out to be approx.104 rad sec-1 for Vertical Barv/sub 0i/xVertical BarC/sub s/Vertical Bar = 10-2, where v/sub 0i/x is the pump-induced drift velocity of the ions and C/sub s/ is the ion acoustic velocity in the plasma

  16. Subharmonics and noise excitation in transmission of acoustic wave through unconsolidated granular medium

    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

  17. Wave Number Method for Three-Dimensional Steady-State Acoustic Problems

    HUANG Fei; HE Zeng; WEI Jun-hong; PENG Wei-cai

    2007-01-01

    Based on the indirect Trefftz approach, a wave number method (WNM) is proposed to deal with three-dimensional steady-state acoustic problems. In the WNM, the dynamic pressure response variable is approximated by a set of wave functions, which exactly satisfy the Helmholtz equation. The set of wave functions comprise the exact solutions of the homogeneous part of the governing equations and some particular solution functions. The unknown coefficients of the wave functions can be obtained by enforcing the pressure approximation to satisfy the boundary conditions. Compared with the boundary element method (BEM), the WNM have a smaller system matrix, and is applicable to the radiation problems since the wave functions are independent of the domain size. A 3D acoustic cavity is exemplified to show the properties of the method. The results show that the wave number method is more efficient than the BEM, and it is fairly accurate.

  18. The patterning mechanism of carbon nanotubes using surface acoustic waves: the acoustic radiation effect or the dielectrophoretic effect.

    Ma, Zhichao; Guo, Jinhong; Liu, Yan Jun; Ai, Ye

    2015-09-01

    In this study, we present a simple technique capable of assembling and patterning suspended CNTs using a standing surface acoustic wave (SSAW) field. Individual CNTs could be assembled into larger CNT bundles and patterned in periodic positions on a substrate surface. The mechanism of the SSAW-based patterning technique has been investigated using both numerical simulation and experimental study. It has been found that the acoustic radiation effect due to the acoustic pressure field and the dielectrophoretic (DEP) effect induced by the electric field co-existing in the patterning process however play different roles depending on the properties of the suspended particles and the suspension medium. In the SSAW-based patterning of highly conductive CNTs with high aspect ratio geometry, the positive DEP effect dominates over the acoustic radiation effect. In contrast, the acoustic radiation effect dominates over the DEP effect when manipulating less conductive, spherical or low aspect ratio particles or biological cells. These results provide a meaningful insight into the mechanism of SSAW-based patterning, which is of great help to guide the effective use of this patterning technique for various applications. PMID:26239679

  19. Effects of ion-atom collisions on the propagation and damping of ion-acoustic waves

    Andersen, H.K.; D'Angelo, N.; Jensen, Vagn Orla;

    1968-01-01

    Experiments are described on ion-acoustic wave propagation and damping in alkali plasmas of various degrees of ionization. An increase of the ratio Te/Ti from 1 to approximately 3-4, caused by ion-atom collisions, results in a decrease of the (Landau) damping of the waves. At high gas pressure and....../or low wave frequency a "fluid" picture adequately describes the experimental results....

  20. Modulational Instability of Ion-Acoustic Waves in a Warm Plasma with a Relativistic Electron Beam

    XUE Ju-Kui; LANG He

    2003-01-01

    The modulational instability of ion-acoustic wave in a collisionless, unmagnetized plasma consisting ofwarm ions, hot isothermal electrons, and relativistic electron beam is studied. A modified nonlinear Schrodinger equationincluding one additional term that comes from the effect of relativistic electron beam is derived. It is found that theinclusion of a relativistic electron beam would modify the modulational instability of the wave packet and could notadmit any stationary soliton waves.

  1. Ultra-Broadband Acoustic Metasurface for Manipulating the Reflected Waves

    Zhu, Yi-Fan; Zou, Xin-Ye; Li, Rui-qi; Jiang, Xue; Tu, Juan; Liang, Bin; Cheng, Jian-Chun

    2014-01-01

    We have designed and experimentally realized an ultra-broadband acoustic metasurface (UBAM) capable of going beyond the intrinsic limitation of bandwidth in existing designs of optical/acoustical metasurfaces. Both the numerical and experimental results demonstrate that the UBAM made of subwavelength gratings can manipulate the reflected phase-front within a bandwidth larger than 2 octaves. A simple physical model based on the phased array theory is developed for interpreting this extraordina...

  2. Damping of an ion acoustic surface wave due to surface currents

    Lee, H J

    1999-01-01

    The well-known linear dispersion relation for an ion acoustic surface wave has been obtained by including the linear surface current density J sub z parallel to the interface and by neglecting the linear surface current density J sub x perpendicular to the interface. The neglect of J sub x is questionable although it leads to the popular boundary condition that the tangential electric field is continuous. In this work, linear dispersion relation for an ion acoustic surface wave is worked out by including both components of the linear current density J . When that is done, the ion acoustic wave turns out to be heavily damped. If the electron mass is taken to be zero (electrons are Bolzmann-distributed), the perpendicular component of the surface current density vanishes, and we have the well-known ion acoustic surface wave eigenmode. We conclude that an ion acoustic surface wave propagates as an eigenmode only when its phase velocity is much smaller than the electron thermal velocity.

  3. Ion-acoustic super rogue waves in ultracold neutral plasmas with nonthermal electrons

    El-Tantawy, S. A. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); El-Bedwehy, N. A. [Department of Mathematics, Faculty of Science, Damietta University, New Damietta 34517 (Egypt); El-Labany, S. K. [Department of Physics, Faculty of Science, Damietta University, New Damietta 34517 (Egypt)

    2013-07-15

    The ion-acoustic rogue waves in ultracold neutral plasmas consisting of ion fluid and nonthermal electrons are reported. A reductive perturbation method is used to obtain a nonlinear Schrödinger equation for describing the system and the modulation instability of the ion-acoustic wave is analyzed. The critical wave number k{sub c}, which indicates where the modulational instability sets in, has been determined. Moreover, the possible region for the ion-acoustic rogue waves to exist is defined precisely. The effects of the nonthermal parameter β and the ions effective temperature ratio σ{sub *} on the critical wave number k{sub c} are studied. It is found that there are two critical wave numbers in our plasma system. For low wave number, increasing β would lead to cringe k{sub c} until β approaches to its critical value β{sub c}, then further increase of β beyond β{sub c} would enhance the values of k{sub c}. For large wave numbers, the increase of β would lead to a decrease of k{sub c}. However, increasing σ{sub *} would lead to the reduction of k{sub c} for all values of the wave number. The dependence of the rogue waves profile on the plasma parameters is numerically examined. It is found that the rogue wave amplitudes have complex behavior with increasing β. Furthermore, the enhancement of σ{sub *} and the carrier wave number k reduces the rogue wave amplitude. It is noticed that near to the critical wave number, the rogue wave amplitude becomes high, but it shrinks whenever we stepped away from k{sub c}. The implications of our results in laboratory ultracold neutral plasma experiments are briefly discussed.

  4. Low-dispersion finite difference methods for acoustic waves in a pipe

    Davis, Sanford

    1991-01-01

    A new algorithm for computing one-dimensional acoustic waves in a pipe is demonstrated by solving the acoustic equations as an initial-boundary-value problem. Conventional dissipation-free second-order finite difference methods suffer severe phase distortion for grids with less that about ten mesh points per wavelength. Using the signal generation by a piston in a duct as an example, transient acoustic computations are presented using a new compact three-point algorithm which allows about 60 percent fewer mesh points per wavelength. Both pulse and harmonic excitation are considered. Coupling of the acoustic signal with the pipe resonant modes is shown to generate a complex transient wave with rich harmonic content.

  5. Wavemaker theories for acoustic-gravity waves over a finite depth

    Tian, Miao; Kadri, Usama

    2016-04-01

    Acoustic-gravity waves (hereafter AGWs) in ocean have received much interest recently, mainly with respect to early detection of tsunamis as they travel at near the speed of sound in water which makes them ideal candidates for early detection of tsunamis. While the generation mechanisms of AGWs have been studied from the perspective of vertical oscillations of seafloor (Yamamoto, 1982; Stiassnie, 2010) and triad wave-wave interaction (Longuet-Higgins 1950; Kadri and Stiassnie 2013; Kadri and Akylas 2016), in the current study we are interested in their generation by wave-structure interaction with possible application to the energy sector. Here, we develop two wavemaker theories to analyze different wave modes generated by impermeable (the classic Havelock's theory) and porous (porous wavemaker theory) plates in weakly compressible fluids. Slight modification has been made to the porous theory so that, unlike the previous theory (Chwang, 1983), the new solution depends on the geometry of the plate. The expressions for three different types of plates (piston, flap, delta-function) are introduced. Analytical solutions are also derived for the potential amplitude of the gravity, evanescent, and acoustic-gravity waves, as well as the surface elevation, velocity distribution, and pressure for AGWs. Both theories reduce to previous results for incompressible flow when the compressibility is negligible. We also show numerical examples for AGW generated in a wave flume as well as in deep ocean. Our current study sets the theoretical background towards remote sensing by AGWs, for optimized deep ocean wave-power harnessing, among others. References Chwang, A.T. 1983 A porous-wavemaker theory. Journal of Fluid Mechanics, 132, 395- 406. Kadri, U., Stiassnie, M. 2013 Generation of an acoustic-gravity wave by two gravity waves, and their subsequent mutual interaction. J. Fluid Mech. 735, R6. Kadri U., Akylas T.R. 2016 On resonant triad interactions of acoustic-gravity waves. J

  6. Computational simulation in architectural and environmental acoustics methods and applications of wave-based computation

    Sakamoto, Shinichi; Otsuru, Toru

    2014-01-01

    This book reviews a variety of methods for wave-based acoustic simulation and recent applications to architectural and environmental acoustic problems. Following an introduction providing an overview of computational simulation of sound environment, the book is in two parts: four chapters on methods and four chapters on applications. The first part explains the fundamentals and advanced techniques for three popular methods, namely, the finite-difference time-domain method, the finite element method, and the boundary element method, as well as alternative time-domain methods. The second part demonstrates various applications to room acoustics simulation, noise propagation simulation, acoustic property simulation for building components, and auralization. This book is a valuable reference that covers the state of the art in computational simulation for architectural and environmental acoustics.  

  7. Novel Acoustic Wave Microsystems for Biophysical Studies of Cells

    Senveli, Sukru Ufuk

    Single cell analysis is an important topic for understanding of diseases. In this understanding, biomechanics approach serves as an important tool as it relates and connects the mechanical properties of biological cells with diseases such as cancer. In this context, analysis methods based on ultrasonics are promising owing to their non-invasive nature and ease of use. However, there is a lack of miniature systems that provide accurate ultrasonic measurements on single cancer cells for diagnostic purposes. The platform presented in this study exploits high frequency acoustic interaction and uses direct coupling of Rayleigh type SAWs with various samples placed inside microcavities to analyze their structural properties. The samples used are aqueous glycerin solutions and polystyrene microbeads for demonstrating proper system operation, and lead up to biological cells. The microcavity is instrumental in trapping a predetermined volume of sample inside and facilitating the interaction of the surface waves with the sample in question via a resonance condition. Ultimately, the resultant SAW reaching the output transducer incurs a phase delay due to its interaction with the sample in the microcavity. The system operates in a different manner compared to similar systems as a result of multiple wave reflections in the small volume and coupling back to the piezoelectric substrate. The proposed microsystem was first analyzed using finite element methods. Liquid and solid media were modeled by considering frequency dependent characteristics. Similarly, mechanical behavior of cells with respect to different conditions is considered, and biological cells are modeled accordingly. Prototype devices were fabricated on quartz and lithium niobate in a cleanroom environment. Process steps were optimized separately for devices with microcavities. Precise fabrication, alignment, and bonding of PDMS microchannels were carried out. Soft microprobes were fabricated out of SU-8, a

  8. Propagation of dust-acoustic waves in weakly ionized plasmas with dust-charge fluctuation

    K K Mondal

    2004-11-01

    For an unmagnetized partially ionized dusty plasma containing electrons, singly charged positive ions, micron-sized massive negatively charged dust grains and a fraction of neutral atoms, dispersion relations for both the dust-ion-acoustic and the dust-acoustic waves have been derived, incorporating dust charge fluctuation. The dispersion relations, under various conditions, have been exhaustively analysed. The explicit expressions for the growth rates have also been derived.

  9. To theory of electromagnetic oscillation of acoustic waves in ferromagnetic media at high temperature

    The method for calculation of acoustic field parameters in ferromagnets, excited by electromagnetoacoustic transducers at high temperatures (in the region of Curie point) is discussed. Calculation is made by the Green function method with account of half-space depth distribution of elementary sources of elastic waves. Physical model of elementary source is presented by combination of three acoustic dipoles, the field of which is described by differential tensor of Green displacements. 17 refs., 4 figs

  10. Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies

    Tadesse, Semere Ayalew; Li, Mo

    2014-01-01

    Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acousto-optic coupling in nanophotonic devices. Here we ...

  11. 3D FEM-BEM coupled resolution for acoustic waves propagation in potential flow

    BALIN, Nolwenn; SYLVAND, Guillaume; Casenave, Fabien

    2012-01-01

    International audience In order to reduce the environmental impact of aircrafts, it is necessary to accurately simulate the acoustics waves propagation in complex environment. A classical method used to compute the noise propagation on large distances is the Boundary Element Method. However this method restricts the flow to a uniform one. To improve the level of modeling, we present here a coupling between Finite Element (FEM) and Boundary Element Methods (BEM) to solve the acoustic propag...

  12. Generation of acoustic rogue waves in dusty plasmas through three-dimensional particle focusing by distorted waveforms

    Tsai, Ya-Yi; Tsai, Jun-Yi; I, Lin

    2016-06-01

    Rogue waves--rare uncertainly emerging localized events with large amplitudes--have been experimentally observed in many nonlinear wave phenomena, such as water waves, optical waves, second sound in superfluid He II (ref. ) and ion acoustic waves in plasmas. Past studies have mainly focused on one-dimensional (1D) wave behaviour through modulation instabilities, and to a lesser extent on higher-dimensional behaviour. The question whether rogue waves also exist in nonlinear 3D acoustic-type plasma waves, the kinetic origin of their formation and their correlation with surrounding 3D waveforms are unexplored fundamental issues. Here we report the direct experimental observation of dust acoustic rogue waves in dusty plasmas and construct a picture of 3D particle focusing by the surrounding tilted and ruptured wave crests, associated with the higher probability of low-amplitude holes for rogue-wave generation.

  13. Three-dimensional manipulation of single cells using surface acoustic waves

    Guo, Feng; Mao, Zhangming; Chen, Yuchao; Xie, Zhiwei; James P Lata; Li, Peng; Ren, Liqiang; Liu, Jiayang; Yang, Jian; Dao, Ming; Suresh, Subra; Huang, Tony Jun

    2016-01-01

    We present 3D acoustic tweezers, which can trap and manipulate single cells and particles along three mutually orthogonal axes of motion by recourse to surface acoustic waves. We use 3D acoustic tweezers to pick up single cells, or entire cell assemblies, and deliver them to desired locations to create 2D and 3D cell patterns, or print the cells into complex shapes. This technology is thus shown to offer better performance over prior cell manipulation techniques in terms of both accurate and ...

  14. Anomalous width variation of rarefactive ion acoustic solitary waves in the context of auroral plasmas

    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.

  15. The Korteweg-de Vries-Zakharov-Kuznetsov equation for electron-acoustic waves

    Motivated by a recent paper [Phys. Plasmas 7, 2987 (2000)] highlighting the potential importance of the electron-acoustic wave in interpreting the solitary waves observed by high time resolution measurements of the electric field in the auroral region, the effect of a magnetic field on weakly nonlinear electron-acoustic waves is investigated. A Korteweg-de Vries-Zakharov-Kuznetsov (KdV-ZK) equation is derived for a plasma comprised of cool and hot electrons and a species of fluid ions. Two models are employed for the ions: magnetized and unmagnetized. When the ions are magnetized the frequency constraints imposed upon the electron-acoustic wave packet prove to be too limiting to be of general use. The second model, which treats the ions as a stationary neutralizing background, overcomes the restrictions imposed by the former and is more fitting for the frequency domain of the electron-acoustic wave. Plane and ellipsoidal soliton solutions are admitted by the KdV-ZK equation, the latter perhaps able to explain some of the two dimensional features of the solitary waves observed in the Earth's high altitude auroral region. Both models for the ions predict only negative potential solitons. It is discussed how the plasma model might be adapted to produce positive potential solitons

  16. Solitonic, periodic and quasiperiodic behaviors of dust ion acoustic waves in superthermal plasmas

    The solitonic, periodic, and quasiperiodic behaviors of dust ion acoustic waves in superthermal plasmas with q-nonextensive electrons are studied using the bifurcation theory of planar dynamical systems through direct approach. Using a Galilean transformation, model equations are transformed to a Hamiltonian system involving electrostatic potential. The existence of solitary and periodic waves is shown for the unperturbed Hamiltonian system. Analytical forms of these waves are presented depending on physical parameters q and μ. The effects of q and μ are studied on characteristics of nonlinear dust ion acoustic solitary and periodic waves. It is observed that parameters q and μ significantly influence the characteristics of nonlinear dust ion acoustic solitary and periodic structures. Considering an external periodic perturbation, the quasiperiodic behavior of the perturbed Hamiltonian system for dust ion acoustic waves is studied. It is seen that the unperturbed Hamiltonian system has the solitary and periodic wave solutions whereas the perturbed Hamiltonian system has quasiperiodic motion for same values of parameters q,μ and v. (author)

  17. Eigenvalue solution to the electron-collisional effect on ion-acoustic and entropy waves

    ZHENG; Jian

    2001-01-01

    [1]Braginskii,S.I.,Transport processes in a plasma,in Reviews of Plasma Physics,Vol.1,New York:Consultants Bureau,1965,205-311.[2]Ono,M.,Kulsrud,R.M.,Frequency and damping of ion acoustic waves,Phys.Fluids,1975,18(10):1287-1293.[3]Randall,C.J.,Effect of ion collisionality on ion-acoustic waves,Phys.Fluids,1982,25(12):2231-2233.[4]Tracy,M.D.,Williams,E.A.,Estabrook,K.G.et al.,Eigenvalue solution for the ion-collisional effects on ion-acoustic and entropy waves,Phys.Fluids,1993,B5(5):1430.[5]Bell,A.R.,Electron energy transport in ion waves and its relevance to laser produced plasmas,Phys.Fluids,1983,26(1):279-284.[6]Epperlein,E.M.,Short,R.W.,Simon,A.,Damping of ion-acoustic waves in the presence of electron-ion collisions,Phys.Rev.Lett.,1992,69(12):1765-1768.[7]Epperlein,E.M.,Effect of electron collisions on ion-acoustic waves and heat flow,Phys.Plasmas,1994,1(1):109-115.[8]Bychenkov,V.Y.,Myatt,J.,Rozmus,W.et al.,Quasihydrodynamic description of ion acoustic waves in a collisional plasmas,Phys.Plasmas,1994,1(8):2419-2429.[9]Bychenkov,V.Y.,Myatt,J.,Rozmus,W.et al.,Ion acoustic waves in plasmas with collisional electrons,Phys.Rev.E,1994,50(6):5134-5137.[10]Bychenkov,V.Y.,Rozmus,W.,Tikhonchuk,V.T.et al.,Nonlocal electron transport in a plasma,Phys.Rev.Lett.,1995,75(24):4405-4408.[11]Zhang,Y.Q.et al.,Density fluctuation spectra of a collision-dominated plasma measured by light scattering,Phys.Rev.Lett.,1989,62(16):1848-1851.[12]Hinton,F.L.,Collisional transport in plasma,in Handbook of Plasma Physics,Vol.1,Amsterdam:North-Holland,1983,147-199.[13]Zheng Jian,Yu Changxuan,A numerical approach to the frequencies and damping rates of ion-acoustic waves in ion-collisional plasmas,Chin.Phys.Lett.,1999,16(12):905-907.[14]Hammett,G.W.,Perkins,F.,Fluid moment models for Landau damping with application to the ion-temperature-gradient instability,Phys.Rev.Lett.,1990,64(25):3019-3022.

  18. Lateral acoustic wave resonator comprising a suspended membrane of low damping resonator material

    Olsson, Roy H.; El-Kady; , Ihab F.; Ziaei-Moayyed, Maryam; Branch; , Darren W.; Su; Mehmet F.,; Reinke; Charles M.,

    2013-09-03

    A very high-Q, low insertion loss resonator can be achieved by storing many overtone cycles of a lateral acoustic wave (i.e., Lamb wave) in a lithographically defined suspended membrane comprising a low damping resonator material, such as silicon carbide. The high-Q resonator can sets up a Fabry-Perot cavity in a low-damping resonator material using high-reflectivity acoustic end mirrors, which can comprise phononic crystals. The lateral overtone acoustic wave resonator can be electrically transduced by piezoelectric couplers. The resonator Q can be increased without increasing the impedance or insertion loss by storing many cycles or wavelengths in the high-Q resonator material, with much lower damping than the piezoelectric transducer material.

  19. Probing thermomechanics at the nanoscale: impulsively excited pseudosurface acoustic waves in hypersonic phononic crystals.

    Nardi, Damiano; Travagliati, Marco; Siemens, Mark E; Li, Qing; Murnane, Margaret M; Kapteyn, Henry C; Ferrini, Gabriele; Parmigiani, Fulvio; Banfi, Francesco

    2011-10-12

    High-frequency surface acoustic waves can be generated by ultrafast laser excitation of nanoscale patterned surfaces. Here we study this phenomenon in the hypersonic frequency limit. By modeling the thermomechanics from first-principles, we calculate the system's initial heat-driven impulsive response and follow its time evolution. A scheme is introduced to quantitatively access frequencies and lifetimes of the composite system's excited eigenmodes. A spectral decomposition of the calculated response on the eigemodes of the system reveals asymmetric resonances that result from the coupling between surface and bulk acoustic modes. This finding allows evaluation of impulsively excited pseudosurface acoustic wave frequencies and lifetimes and expands our understanding of the scattering of surface waves in mesoscale metamaterials. The model is successfully benchmarked against time-resolved optical diffraction measurements performed on one-dimensional and two-dimensional surface phononic crystals, probed using light at extreme ultraviolet and near-infrared wavelengths. PMID:21910426

  20. Local helioseismic and spectroscopic analyses of interactions between acoustic waves and a sunspot

    Rajaguru, S P; Sankarasubramanian, K; Couvidat, S; 10.1088/2041-8205/721/2/L86

    2010-01-01

    Using a high cadence imaging spectropolarimetric observation of a sunspot and its surroundings in magnetically sensitive (FeI 6173 A) and insensitive (FeI 7090 A) upper photospheric absorption lines, we map the instantaneous wave phases and helioseismic travel times as a function of observation height and inclination of magnetic field to the vertical. We confirm the magnetic inclination angle dependent transmission of incident acoustic waves into upward propagating waves, and derive (1) proof that helioseismic travel times receive direction dependent contributions from such waves and hence cause errors in conventional flow inferences, (2) evidences for acoustic wave sources beneath the umbral photosphere, and (3) significant differences in travel times measured from the chosen magnetically sensitive and insensitive spectral lines.

  1. On Mode Conversion, Reflection and Transmission of Magneto-Acoustic Waves from Above in an Isothermal Stratified Atmosphere

    Hansen, Shelley; Donea, Alina

    2015-01-01

    We use the exact solutions for magnetoacoustic waves in a two dimensional isothermal atmosphere with uniform inclined magnetic field to calculate the wave reflection, transmission, and conversion of slow and fast waves incident from above ($z=\\infty$). This is relevant to the question of whether waves excited by flares in the solar atmosphere can penetrate the Alfv\\'en/acoustic equipartition layer (which we identify as the canopy) to reach the photosphere with sufficient energy to create sunquakes. It is found that slow waves above the acoustic cutoff frequency efficiently penetrate (transmit) as acoustic (fast) waves if directed at a small attack angle to the magnetic field, with the rest converting to magnetic (slow) waves, in accord with Generalized Ray Theory. This may help explain the compact nature of seismic sources of sunquakes identified using seismic holography. The incident slow waves can also efficiently transmit at low frequency in inclined field due to the reduction in acoustic cutoff frequency ...

  2. Acoustic wave detection of chemical species electrokinetically transported within a capillary tube.

    Li, Paul C H; Prasad, Ronald

    2003-06-01

    For the first time, we report the acoustic wave detection of chemical species being transported in a capillary tube to a region where acoustic coupling occurs. The measured parameter was a change in phase, which was originally only attributed to a change in solution density as the analyte passed by the detection region. Accordingly, we report the detection of change in phase as various chemical species (e.g. Cy5 dye, Cy5-derivatized glycine and underivatized glycine) were introduced into and migrated along a capillary tube through electrokinetic processes. To improve detection sensitivity, we modified various experimental parameters, such as run buffer concentration, capillary wall thickness and transducer frequency. Although acoustic wave detection was feasible, the peak width and detection limit were inadequate as compared to conventional detection methods for HPLC or CE. Nevertheless, the effects of various physical and chemical relaxation processes on acoustic wave absorption were discussed, and this has shed some light on explaining some observations, which cannot be explained by density differences alone. Accordingly, the acoustic wave method is suggested to investigate these processes, as studied in ultrasonic relaxation spectroscopy, in a flow system. PMID:12866892

  3. Acoustic propagation through anisotropic internal wave fields: Transmission loss, cross-range coherence, and horizontal refraction

    Oba, Roger; Finette, Steven

    2002-02-01

    Results of a computer simulation study are presented for acoustic propagation in a shallow water, anisotropic ocean environment. The water column is characterized by random volume fluctuations in the sound speed field that are induced by internal gravity waves, and this variability is superimposed on a dominant summer thermocline. Both the internal wave field and resulting sound speed perturbations are represented in three-dimensional (3D) space and evolve in time. The isopycnal displacements consist of two components: a spatially diffuse, horizontally isotropic component and a spatially localized contribution from an undular bore (i.e., a solitary wave packet or solibore) that exhibits horizontal (azimuthal) anisotropy. An acoustic field is propagated through this waveguide using a 3D parabolic equation code based on differential operators representing wide-angle coverage in elevation and narrow-angle coverage in azimuth. Transmission loss is evaluated both for fixed time snapshots of the environment and as a function of time over an ordered set of snapshots which represent the time-evolving sound speed distribution. Horizontal acoustic coherence, also known as transverse or cross-range coherence, is estimated for horizontally separated points in the direction normal to the source-receiver orientation. Both transmission loss and spatial coherence are computed at acoustic frequencies 200 and 400 Hz for ranges extending to 10 km, a cross-range of 1 km, and a water depth of 68 m. Azimuthal filtering of the propagated field occurs for this environment, with the strongest variations appearing when propagation is parallel to the solitary wave depressions of the thermocline. A large anisotropic degradation in horizontal coherence occurs under the same conditions. Horizontal refraction of the acoustic wave front is responsible for the degradation, as demonstrated by an energy gradient analysis of in-plane and out-of-plane energy transfer. The solitary wave packet is

  4. Auroral ion beams and ion acoustic wave generation by fan instability

    Satellite observations indicate that efficient energy transport among various plasma particles and between plasma waves and plasma particles is taking place in auroral ion beam regions. These observations show that two characteristic wave types are associated with the auroral ion beam regions: electrostatic hydrogen cyclotron waves with frequencies above hydrogen gyrofrequency, and low frequency waves with frequencies below hydrogen gyrofrequency. We speculate that the low frequency waves can be ion acoustic waves generated through the fan instability. The presence of a cold background ion component is necessary for the onset of this instability. A cold ion component has been directly observed and has been indirectly suggested from observations of solitary wave structures. The wave-particle interaction during the development of the fan instability results in an efficient ion beam heating in the direction perpendicular to the ambient magnetic field. The fan instability development and the ion beam heating is demonstrated in a numerical particle simulation. 23 refs, 16 figs

  5. Slow Magneto-acoustic Waves Observed above Quiet-Sun Region in a Dark Cavity

    Liu, Jiajia; Wang, Yuming; Liu, Rui; Wang, Bin; Liao, Chijian; Shen, Chenglong; Zheng, Huinan; Miao, Bin; Su, Zhenpeng; Wang, S

    2012-01-01

    Waves play a crucial role in diagnosing the plasma properties of various structures in the solar corona and coronal heating. Slow magneto-acoustic (MA) waves are one of the important magnetohydrodynamic waves. In past decades, numerous slow MA waves were detected above the active regions and coronal holes, but rarely found elsewhere. Here, we investigate a `tornado'-like structure consisting of quasi-periodic streaks within a dark cavity at about 40--110 Mm above the quiet-Sun region on 2011 September 25. Our analysis reveals that these streaks are actually slow MA wave trains. The properties of these wave trains, including the phase speed, compression ratio, kinetic energy density, etc., are similar to those of the reported slow MA waves, except that the period of these waves is about 50 s, much shorter than the typical reported values (3--5 minutes).

  6. Modulation of electron-acoustic waves in a plasma with kappa distribution

    Demiray, Hilmi

    2016-03-01

    In the present work, employing a one dimensional model of an unmagnetized collisionless plasma consisting of a cold electron fluid, hot electrons obeying κ velocity distribution, and stationary ions, we study the amplitude modulation of an electron-acoustic waves by use of the conventional reductive perturbation method. Employing the field equations of such a plasma, we obtained the nonlinear Schrödinger equation as the evolution equation. Seeking a harmonic wave solution with progressive wave amplitude to the evolution equation, as opposed to the plasma with vortex distribution, the amplitude wave assumes a shock wave type of solution. Finally, the modulational stability of the wave is studied and it is observed that the wave is modulationally stable for all admissible wave numbers.

  7. Adjustable, rapidly switching microfluidic gradient generation using focused travelling surface acoustic waves

    Destgeer, Ghulam; Im, Sunghyuk; Hang Ha, Byung; Ho Jung, Jin; Ahmad Ansari, Mubashshir; Jin Sung, Hyung, E-mail: hjsung@kaist.ac.kr [Department of Mechanical Engineering, KAIST, 291 Daejak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2014-01-13

    We demonstrate a simple device to generate chemical concentration gradients in a microfluidic channel using focused travelling surface acoustic waves (F-TSAW). A pair of curved interdigitated metal electrodes deposited on the surface of a piezoelectric (LiNbO{sub 3}) substrate disseminate high frequency sound waves when actuated by an alternating current source. The F-TSAW produces chaotic acoustic streaming flow upon its interaction with the fluid inside a microfluidic channel, which mixes confluent streams of chemicals in a controlled fashion for an adjustable and rapidly switching gradient generation.

  8. Measurement of shock-induced guided and surface acoustic waves along boreholes in poroelastic materials

    Chao, G; Smeulders, D.M.J.; Van Dongen, M.E.H.

    2006-01-01

    Acoustic experiments on the propagation of guided waves along water-filled boreholes in water-saturated porous materials are reported. The experiments were conducted using a shock tube technique. An acoustic funnel structure was placed inside the tube just above the sample in order to enhance the excitation of the surface modes. A fast Fourier transform-Prony-spectral ratio method is implemented to transform the data from the time-space domain to the frequency-wave-number domain. Frequency-de...

  9. Experimental study on the relation between the water content of surface soil and the acoustic wave

    2001-01-01

    In order to investigate the relation between the water content changing of surface soil and micro-quake recorded before earthquakes, we carried out a simulation experiment in laboratory. Its purpose is to explore whether the acoustic wave generated by micro-fracturing before earthquake are able to change water content of surface soil, so as to understand the relation between thermal anomaly in the remote sensing image got from the seismogenic area and the coming earthquake. The result of the experiment shows that when the acoustic wave enters into the surface soil the water content here increases on the background of decreasing due to natural evaporation. In the meantime, temperature here decreases.

  10. Theoretical mass sensitivity of Love wave and layer guided acoustic plate mode sensors

    McHale, Glen; Newton, Michael; Martin, Fabrice

    2002-01-01

    A model for the mass sensitivity of Love wave and layer guided shear horizontal acoustic plate mode (SH–APM) sensors is developed by considering the propagation of shear horizontally polarized acoustic waves in a three layer system. A dispersion equation is derived for this three layer system and this is shown to contain the dispersion equation for the two layer system of the substrate and the guiding layer plus a term involving the third layer, which is regarded as a perturbing mass layer. T...

  11. X33 cut quartz for temperature compensated SAW (Surface Acoustic Wave) devices

    Webster, Richard T.

    1986-07-01

    An X-cut, 33.44 degree quartz crystal for propagating surface acoustic waves with a temperature stability in the order of - 0.0209 ppm/sq.cm. is described. The crystal orientation requires only a single rotation (33.44 degrees) from the crystal axes. This orientation is substantially simpler than previously reported cuts with comparable temperature stability which typically require three rotations. The X-cut orientation has a surface acoustic wave (SAW) velocity of 3175 m/sec, an electromechanical coupling of 0.0004, and a power flow angle of 2.7 degrees.

  12. Numerical modelling of the structure of electromagnetic disturbances generated by acoustic-gravity waves

    A numeric model of electromagnetic field disturbances generated under the interaction of acoustic-gravitational waves with ionospheric plasma is elaborated and vertical structure of the above disturbances is calculated. The estimates shown that electromagnetic disturbances can penetrate into neutral atmosphere and can be recorded through measurements of the variation of magnetic field and electron field vertical component near the earth is surface. A conclusion is made on a feasibility of monitoring of acoustic-gravitational wave activity in the lower thermosphere through land measurements of magnetic and electric field variations

  13. Nonlinear dust-ion-acoustic waves in a multi-ion plasma with trapped electrons

    S S Duha; B Shikha; A A Mamun

    2011-08-01

    A dusty multi-ion plasma system consisting of non-isothermal (trapped) electrons, Maxwellian (isothermal) light positive ions, warm heavy negative ions and extremely massive charge fluctuating stationary dust have been considered. The dust-ion-acoustic solitary and shock waves associated with negative ion dynamics, Maxwellian (isothermal) positive ions, trapped electrons and charge fluctuating stationary dust have been investigated by employing the reductive perturbation method. The basic features of such dust-ion-acoustic solitary and shock waves have been identified. The implications of our findings in space and laboratory dusty multi-ion plasmas are discussed.

  14. Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films

    Hines, Jacqueline H. (Inventor)

    2015-01-01

    A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.

  15. Specific Features of Destabilization of the Wave Profile During Reflection of an Intense Acoustic Beam from a Soft Boundary

    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.

  16. Spherical Kadomtsev–Petviashviliequation for dust acoustic waves with dust size distribution and two-charges-ions

    K Annou; S Bahamida; R Annou

    2011-03-01

    The nonlinear dust acoustic waves in dusty plasmas with negative as well as positive ions and the combined effects of bounded spherical geometry and the transverse perturbation and the size distribution of dust grains are studied. Using the perturbation method, a spherical Kadomtsev–Petviashvili (SKP) equation that describes the dust acoustic waves is deduced.

  17. Ion-acoustic solitary waves and spectrally uniform scattering cross section enhancements

    J. Ekeberg

    2010-06-01

    Full Text Available Spectra measured by incoherent scatter radars are formed predominantly by scattering of the incident signal off ion-acoustic and Langmuir waves in the ionosphere. Occasionally, the upshifted and/or downshifted lines produced by the ion-acoustic waves are enhanced well above thermal levels and referred to as naturally enhanced ion-acoustic lines. In this paper, we study another kind of enhancement, which is spectrally uniform over the whole ion-line, i.e. the up- and downshifted shoulder and the spectral valley in between. Based on observations made with the EISCAT Svalbard radar (ESR facility, we investigate the transient and spectrally uniform power enhancements, which can be explained by ion-acoustic solitary waves. We use a theory of nonlinear waves in a magnetized plasma to determine the properties of such waves and evaluate their effects on scattered signals measured by ESR. We suggest a new mechanism that can explain backscattered power enhancements by one order of magnitude above the thermal level and show that it is consistent with observations.

  18. Modeling of acoustic and gravity waves propagation through the atmosphere with spectral element method

    Brissaud, Q.; Garcia, R.; Martin, R.; Komatitsch, D.

    2014-12-01

    Low-frequency events such as tsunamis generate acoustic and gravity waves which quickly propagate in the atmosphere. Since the atmospheric density decreases exponentially as the altitude increases and from the conservation of the kinetic energy, those waves see their amplitude raise (to the order of 105 at 200km of altitude), allowing their detection in the upper atmosphere. Various tools have been developed through years to model this propagation, such as normal modes modeling or to a greater extent time-reversal techniques, but none offer a low-frequency multi-dimensional atmospheric wave modelling.A modeling tool is worthy interest since there are many different phenomena, from quakes to atmospheric explosions, able to propagate acoustic and gravity waves. In order to provide a fine modeling of the precise observations of these waves by GOCE satellite data, we developed a new numerical modeling tool.Starting from the SPECFEM program that already propagate waves in solid, porous or fluid media using a spectral element method, this work offers a tool with the ability to model acoustic and gravity waves propagation in a stratified attenuating atmosphere with a bottom forcing or an atmospheric source.Atmospheric attenuation is required in a proper modeling framework since it has a crucial impact on acoustic wave propagation. Indeed, it plays the role of a frequency filter that damps high-frequency signals. The bottom forcing feature has been implemented due to its ability to easily model the coupling with the Earth's or ocean's surface (that vibrates when a surface wave go through it) but also huge atmospheric events.

  19. Interaction of acoustic-gravity waves with an elastic shelf-break

    Tian, Miao; Kadri, Usama

    2016-04-01

    In contrast to surface gravity waves that induce flow field which decays exponentially with depth, acoustic-gravity waves oscillate throughout the water column. Their oscillatory profile exerts stresses to the ground which provides a natural explanation for the earth's microseism (Longuet-Higgins, 1950). This work is an extension of the shelf-break problem by Kadri and Stiassnie (2012) who considered the sea floor and the shelf-break to be rigid, and the elastic problem by Eyov et al. (2013) who illustrated the importance of the sea-floor elasticity. In this study we formulate and solve the two-dimensional problem of an incident acoustic-gravity wave mode propagating over an elastic wall and interacting with a shelf-break in a weakly compressible fluid. As the modes approach the shelf-break, part of the energy is reflected whereas the other part is transmitted. A mathematical model is formulated by matching particular solutions for each subregion of constant depth along vertical boundaries; the resulting matrix equation is then solved numerically. The physical properties of these waves are studied, and compared with those for waves over a rigid bottom. The present work broadens our knowledge of acoustic-gravity-waves propagation in realistic environment and can potentially benefit the early detection of tsunami, generated from landslides or submarine earthquakes. References Eyov E., Klar A., Kadri U. , Stiassnie M. 2013 Progressive waves in a compressible-ocean with an elastic bottom. Wave Motion 50, 929-939. Kadri, U., and M. Stiassnie, 2012 Acoustic-Gravity waves interacting with the shelf break. J. Geophys. Res. 117, C03035. Longuet-Higgins, M.S. 1950 A theory of the origin of microseisms. Philos. Trans. R. Soc. Lond. A 243, 1-35.

  20. Possible variations of E-layer electromagnetic fields by acoustic waves above earthquake preparation regions

    Meister, C.-V.; Mayer, B.; Hoffmann, D. H. H.

    2012-04-01

    The many-fluid magnetohydrodynamic theory is applied to describe the modification of the electromagnetic field of the ionospheric E-layer by acoustic-type waves. These waves originate from lower altitudes and may be caused by earthquake preparation processes. In comparison to former works, the different stratification of the positively and negatively charged ionospheric particles and of the neutral constituents is taken into account. There also the influence of the mean electric field on the different hight scales of the plasma parameters is discussed. Besides, the hight scales of the electric and magnetic wave fields are modeled. It is shown that at E-layer altitudes the acoustic waves may be converted into Alfvén waves. The dependence of these waves on the height scales of the plasma parameters of the particles and on the momentum transport between the charged and neutral particles is analysed. First estimates of the temperature variations within the E-layer because of the assumed acoustic-type waves of seismic origin are made.

  1. Dynamic motions of ion acoustic waves in plasmas with superthermal electrons

    Saha, Asit, E-mail: asit_saha123@rediffmail.com [Department of Mathematics, Sikkim Manipal Institute of Technology (India); Chatterjee, Prasanta [Department of Mathematics, Siksha Bhavana, Visva Bharati University (India); Wong, C.S. [Plasma Technology Research Centre, Department of Physics, University of Malaya, Kuala Lampur (Malaysia)

    2015-12-15

    The dynamic motions of ion acoustic waves an unmagnetized plasma with superthermal (q-non extensive) electrons are investigated employing the bifurcation theory of planar dynamical systems through direct approach. Using traveling wave transformation and initial conditions, basic equations are transformed to a planar dynamical system. Using numerical computations, all possible phase portraits of the dynamical system are presented. Corresponding to homoclinic and periodic orbits of the phase portraits, two new analytical forms of solitary and periodic wave solutions are derived depending on the non extensive parameter q and speed v of the traveling wave. Considering an external periodic perturbation, the quasiperiodic and chaotic motions of ion acoustic waves are presented. Depending upon different ranges of non extensive parameter q, the effect of q is shown on quasiperiodic and chaotic motions of ion acoustic waves with fixed value of v. It is seen that the unperturbed dynamical system has the solitary and periodic wave solutions, but the perturbed dynamical system has the quasiperiodic and chaotic motions with same values of parameters q and v. (author)

  2. Experimental study of nonlinear dust acoustic solitary waves in a dusty plasma

    Bandyopadhyay, P; Sen, A; Kaw, P K

    2008-01-01

    The excitation and propagation of finite amplitude low frequency solitary waves are investigated in an Argon plasma impregnated with kaolin dust particles. A nonlinear longitudinal dust acoustic solitary wave is excited by pulse modulating the discharge voltage with a negative potential. It is found that the velocity of the solitary wave increases and the width decreases with the increase of the modulating voltage, but the product of the solitary wave amplitude and the square of the width remains nearly constant. The experimental findings are compared with analytic soliton solutions of a model Kortweg-de Vries equation.

  3. Resonant interaction of edge dislocations with running acoustic waves

    The interaction of equilibrium clusters of straight edge dislocations with a monochromatic sound wave having a non-zero wavevector is investigated taking into account the dislocation mass. We report on a significant increase in drift velocities of clusters when the sound wave frequency approaches a cluster's eigenfrequency. Of practical importance is the increase in the drift velocity observed for clusters with a non-zero topological charge interacting with small frequency sound waves

  4. On-chip manipulation of single microparticles, cells, and organisms using surface acoustic waves

    Ding, Xiaoyun; Lin, Sz-Chin Steven; Kiraly, Brian; Yue, Hongjun; Li, Sixing; Chiang, I-Kao; Shi, Jinjie; Benkovic, Stephen J.; Huang, Tony Jun

    2012-01-01

    Techniques that can dexterously manipulate single particles, cells, and organisms are invaluable for many applications in biology, chemistry, engineering, and physics. Here, we demonstrate standing surface acoustic wave based “acoustic tweezers” that can trap and manipulate single microparticles, cells, and entire organisms (i.e., Caenorhabditis elegans) in a single-layer microfluidic chip. Our acoustic tweezers utilize the wide resonance band of chirped interdigital transducers to achieve real-time control of a standing surface acoustic wave field, which enables flexible manipulation of most known microparticles. The power density required by our acoustic device is significantly lower than its optical counterparts (10,000,000 times less than optical tweezers and 100 times less than optoelectronic tweezers), which renders the technique more biocompatible and amenable to miniaturization. Cell-viability tests were conducted to verify the tweezers’ compatibility with biological objects. With its advantages in biocompatibility, miniaturization, and versatility, the acoustic tweezers presented here will become a powerful tool for many disciplines of science and engineering. PMID:22733731

  5. Difference-frequency generation in nonlinear scattering of acoustic waves by a rigid sphere

    Silva, Glauber T

    2012-01-01

    In this paper, the partial-wave expansion method is applied to describe the difference-frequency pressure generated in a nonlinear scattering of two acoustic waves with an arbitrary wavefront by means of a rigid sphere. Particularly, the difference-frequency generation is analyzed in the nonlinear scattering with a spherical scatterer involving two intersecting plane waves in the following configurations: collinear, crossing at right angles, and counter-propagating. For the sake simplicity, the plane waves are assumed to be spatially located in a spherical region which diameter is smaller than the difference-frequency wavelength. Such arrangements can be experimentally accomplished in vibro-acoustography and nonlinear acoustic tomography techniques. It turns out to be that when the sphere radius is of the order of the primary wavelengths, and the downshift ratio (i.e. the ratio between the fundamental frequency and the difference-frequency) is larger than five, difference-frequency generation is mostly due to...

  6. Energy storage and dispersion of surface acoustic waves trapped in a periodic array of mechanical resonators

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2009-01-01

    resonators storing mechanical energy. These resonators are evanescently coupled by the surface. The dispersion diagram is presented and shows very low group velocities as the wave vector approaches the limit of the first Brillouin zone. ©2009 American Institute of Physics......It has been shown previously that surface acoustic waves can be efficiently trapped and slowed by steep ridges on a piezoelectric substrate, giving rise to two families of shear-horizontal and vertically polarized surface waves. The mechanisms of energy storage and dispersion are explored by using...... the finite element method to model surface acoustic waves generated by high aspect ratio electrodes. A periodic model is proposed including a perfectly matched layer to simulate radiation conditions away from the sources, from which the modal distributions are found. The ratio of the mechanical energy...

  7. Propagation of acoustic shock waves between parallel rigid boundaries and into shadow zones

    Desjouy, C., E-mail: cyril.desjouy@gmail.com; Ollivier, S.; Dragna, D.; Blanc-Benon, P. [Laboratoire de Mécanique des Fluides et d’Acoustique, UMR CNRS 5509, École Centrale de Lyon, Université de Lyon, 69134 Ecully Cedex (France); Marsden, O. [European Center For Medium Range Weather Forecasts, United Kingdom Shinfield (United Kingdom)

    2015-10-28

    The study of acoustic shock propagation in complex environments is of great interest for urban acoustics, but also for source localization, an underlying problematic in military applications. To give a better understanding of the phenomenon taking place during the propagation of acoustic shocks, laboratory-scale experiments and numerical simulations were performed to study the propagation of weak shock waves between parallel rigid boundaries, and into shadow zones created by corners. In particular, this work focuses on the study of the local interactions taking place between incident, reflected, and diffracted waves according to the geometry in both regular or irregular – also called Von Neumann – regimes of reflection. In this latter case, an irregular reflection can lead to the formation of a Mach stem that can modify the spatial distribution of the acoustic pressure. Short duration acoustic shock waves were produced by a 20 kilovolts electric spark source and a schlieren optical method was used to visualize the incident shockfront and the reflection/diffraction patterns. Experimental results are compared to numerical simulations based on the high-order finite difference solution of the two dimensional Navier-Stokes equations.

  8. Propagation of acoustic shock waves between parallel rigid boundaries and into shadow zones

    The study of acoustic shock propagation in complex environments is of great interest for urban acoustics, but also for source localization, an underlying problematic in military applications. To give a better understanding of the phenomenon taking place during the propagation of acoustic shocks, laboratory-scale experiments and numerical simulations were performed to study the propagation of weak shock waves between parallel rigid boundaries, and into shadow zones created by corners. In particular, this work focuses on the study of the local interactions taking place between incident, reflected, and diffracted waves according to the geometry in both regular or irregular – also called Von Neumann – regimes of reflection. In this latter case, an irregular reflection can lead to the formation of a Mach stem that can modify the spatial distribution of the acoustic pressure. Short duration acoustic shock waves were produced by a 20 kilovolts electric spark source and a schlieren optical method was used to visualize the incident shockfront and the reflection/diffraction patterns. Experimental results are compared to numerical simulations based on the high-order finite difference solution of the two dimensional Navier-Stokes equations

  9. An investigation of the influence of acoustic waves on the liquid flow through a porous material.

    Poesio, Pietro; Ooms, Gijs; Barake, Sander; van der Bas, Fred

    2002-05-01

    An experimental and theoretical investigation has been made of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material. The experiments have been performed on Berea sandstone cores. Two acoustic horns were used with frequencies of 20 and 40 kHz, and with maximum power output of 2 and 0.7 kW, respectively. Also, a temperature measurement of the flowing liquid inside the core was made. A high external pressure was applied in order to avoid cavitation. The acoustic waves were found to produce a significant effect on the pressure gradient at constant liquid flow rate through the core samples. During the application of acoustic waves the pressure gradient inside the core decreases. This effect turned out to be due to the decrease of the liquid viscosity caused by an increase in liquid temperature as a result of the acoustic energy dissipation inside the porous material. Also, a theoretical model has been developed to calculate the dissipation effect on the viscosity and on the pressure gradient. The model predictions are in reasonable agreement with the experimental data. PMID:12051421

  10. An investigation of the influence of acoustic waves on the liquid flow through a porous material

    Poesio, Pietro; Ooms, Gijs; Barake, Sander; van der Bas, Fred

    2002-05-01

    An experimental and theoretical investigation has been made of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material. The experiments have been performed on Berea sandstone cores. Two acoustic horns were used with frequencies of 20 and 40 kHz, and with maximum power output of 2 and 0.7 kW, respectively. Also, a temperature measurement of the flowing liquid inside the core was made. A high external pressure was applied in order to avoid cavitation. The acoustic waves were found to produce a significant effect on the pressure gradient at constant liquid flow rate through the core samples. During the application of acoustic waves the pressure gradient inside the core decreases. This effect turned out to be due to the decrease of the liquid viscosity caused by an increase in liquid temperature as a result of the acoustic energy dissipation inside the porous material. Also, a theoretical model has been developed to calculate the dissipation effect on the viscosity and on the pressure gradient. The model predictions are in reasonable agreement with the experimental data.

  11. Characteristics of acoustic wave from atmospheric nuclear explosions conducted at the USSR Test Sites

    Sokolova, Inna

    2015-04-01

    Availability of the acoustic wave on the record of microbarograph is one of discriminate signs of atmospheric (surface layer of atmosphere) and contact explosions. Nowadays there is large number of air wave records from chemical explosions recorded by the IMS infrasound stations installed during recent decade. But there is small number of air wave records from nuclear explosions as air and contact nuclear explosions had been conducted since 1945 to 1962, before the Limited Test Ban Treaty was signed in 1963 (the treaty banning nuclear weapon tests in the atmosphere, in outer space and under water) by the Great Britain, USSR and USA. That time there was small number of installed microbarographs. First infrasound stations in the USSR appeared in 1954, and by the moment of the USSR collapse the network consisted of 25 infrasound stations, 3 of which were located on Kazakhstan territory - in Kurchatov (East Kazakhstan), in Borovoye Observatory (North Kazakhstan) and Talgar Observatory (Northern Tien Shan). The microbarograph of Talgar Observatory was installed in 1962 and recorded large number of air nuclear explosions conducted at Semipalatinsk Test Site and Novaya Zemlya Test Site. The epicentral distance to the STS was ~700 km, and to Novaya Zemlya Test Site ~3500 km. The historical analog records of the microbarograph were analyzed on the availability of the acoustic wave. The selected records were digitized, the database of acoustic signals from nuclear explosions was created. In addition, acoustic signals from atmospheric nuclear explosions conducted at the USSR Test Sites were recorded by analogue broadband seismic stations at wide range of epicentral distances, 300-3600 km. These signals coincide well by its form and spectral content with records of microbarographs and can be used for monitoring tasks and discrimination in places where infrasound observations are absent. Nuclear explosions which records contained acoustic wave were from 0.03 to 30 kt yield for

  12. Enhanced sensitivity of a surface acoustic wave gyroscope using a progressive wave

    A surface acoustic wave (SAW)-based gyroscope with an 80 MHz central frequency was developed on two different piezoelectric substrates (128° YX LiNbO3 and ST-X quartz). A sensor was developed that contained two SAW oscillators. One oscillator was used as the sensing element and had metallic dots in the cavity between the input and output interdigital transducers (IDTs). The other oscillator was used as a reference element. Two oscillators were formed to extract the Coriolis effect by comparing the oscillation frequencies between these two delay lines, and metallic dots were used to induce a Coriolis force. Three different IDT structures were used to obtain a stable progressive SAW. Coupling of modes modeling was conducted prior to fabrication for determining the optimal device parameters. The device was fabricated and then measured on a rate table in accordance with the results of simulation. When the device was subjected to an angular rotation, the oscillation frequencies of the two oscillators were observed to differ. Depending on the angular velocity, the frequency difference was linearly modulated. The obtained sensitivity was approximately 62.57 Hz deg−1 s−1 at angular rates in the range 0–1000 deg s−1 in the case of the LiNbO3 substrate and single-phase unidirectional transducer and combed electrode structure. The dependence of the device performance on the piezoelectric substrate, IDT structure, and temperatures was also characterized. The developed device has good resistance to mechanical shock and stability to temperature

  13. Tsunami and acoustic-gravity waves in water of constant depth

    Hendin, Gali; Stiassnie, Michael [Faculty of Civil and Environmental Engineering, Technion – Israel institute of technology, Haifa 32000 (Israel)

    2013-08-15

    A study of wave radiation by a rather general bottom displacement, in a compressible ocean of otherwise constant depth, is carried out within the framework of a three-dimensional linear theory. Simple analytic expressions for the flow field, at large distance from the disturbance, are derived. Realistic numerical examples indicate that the Acoustic-Gravity waves, which significantly precede the Tsunami, are expected to leave a measurable signature on bottom-pressure records that should be considered for early detection of Tsunami.

  14. Modulation of electron-acoustic waves in a plasma with kappa distribution

    Demiray, Hilmi

    2016-01-01

    In the present work, employing a one dimensional model of an unmagnetized collisionless plasma consisting of a cold electron fluid, hot electrons obeying κ velocity distribution, and stationary ions, we study the amplitude modulation of an electron-acoustic waves by use of the conventional reductive perturbation method. Employing the field equations of such a plasma, we obtained the nonlinear Schrödinger equation as the evolution equation. Seeking a harmonic wave solution with progressive wav...

  15. Tsunami and acoustic-gravity waves in water of constant depth

    A study of wave radiation by a rather general bottom displacement, in a compressible ocean of otherwise constant depth, is carried out within the framework of a three-dimensional linear theory. Simple analytic expressions for the flow field, at large distance from the disturbance, are derived. Realistic numerical examples indicate that the Acoustic-Gravity waves, which significantly precede the Tsunami, are expected to leave a measurable signature on bottom-pressure records that should be considered for early detection of Tsunami

  16. Numerical modeling of acoustic and gravity waves propagation in the atmosphere using a spectral element method

    Martin, Roland; Brissaud, Quentin; Garcia, Raphael; Komatitsch, Dimitri

    2015-04-01

    During low-frequency events such as tsunamis, acoustic and gravity waves are generated and quickly propagate in the atmosphere. Due to the exponential decrease of the atmospheric density with the altitude, the conservation of the kinetic energy imposes that the amplitude of those waves increases (to the order of 105 at 200km of altitude), which allows their detection in the upper atmosphere. This propagation bas been modelled for years with different tools, such as normal modes modeling or to a greater extent time-reversal techniques, but a low-frequency multi-dimensional atmospheric wave modelling is still crucially needed. A modeling tool is worth of interest since there are many different sources, as earthquakes or atmospheric explosions, able to propagate acoustic and gravity waves. In order to provide a fine modeling of the precise observations of these waves by GOCE satellite data, we developed a new numerical modeling tool. By adding some developments to the SPECFEM package that already models wave propagation in solid, porous or fluid media using a spectral element method, we show here that acoustic and gravity waves propagation can now be modelled in a stratified attenuating atmosphere with a bottom forcing or an atmospheric source. The bottom forcing feature has been implemented to easily model the coupling with the Earth's or ocean's vibrating surfaces but also huge atmospheric events. Atmospheric attenuation is also introduced since it has a crucial impact on acoustic wave propagation. Indeed, it plays the role of a frequency filter that damps high-frequency signals.

  17. Tsunami and acoustic-gravity waves in water of constant depth

    Hendin, Gali; Stiassnie, Michael

    2013-08-01

    A study of wave radiation by a rather general bottom displacement, in a compressible ocean of otherwise constant depth, is carried out within the framework of a three-dimensional linear theory. Simple analytic expressions for the flow field, at large distance from the disturbance, are derived. Realistic numerical examples indicate that the Acoustic-Gravity waves, which significantly precede the Tsunami, are expected to leave a measurable signature on bottom-pressure records that should be considered for early detection of Tsunami.

  18. Use of multiple acoustic wave modes for assessment of long bones: Model study

    Tatarinov, Alexey; Sarvazyan, Noune; Sarvazyan, Armen

    2005-01-01

    Multiple acoustic wave mode method has been proposed as a new modality in axial bone QUS. The new method is based on measurement of ultrasound velocity at different ratio of wavelength to the bone thickness, and taking into account both bulk and guided waves. It allows assessment of changes in both the material properties related to porosity and mineralization as well as the cortical thickness influenced by resorption from inner layers, which are equally important in diagnostics of osteoporos...

  19. Stimulated Brillouin scattering for generating an acoustic wave in optical fibers

    Holík, M.; Mikel, Břetislav; Urban, F.

    Bellingham : SPIE, 2012, 86971I:1-6. ISBN 978-0-8194-9481-8. [CPS 2012. Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics /18./. Ostravice (CZ), 03.09.2012-07.09.2012] R&D Projects: GA TA ČR TA01010995 Institutional support: RVO:68081731 Keywords : stimulated Brillouin scattering * acoustic wave * optical fiber Subject RIV: BH - Optics, Masers, Laser s

  20. Conditions for the Observation of Two Ion-Acoustic Waves via Thomson Scattering

    郑坚; 胡广月; 王哲斌; 俞昌旋; 刘万东

    2003-01-01

    Observation of two ion-acoustic waves via Thomson scattering can provide precise measurements of plasma parameters. The conditions for the observation of two ion-acoustic modes in a two-ion plasmaare discussed.The ratio of electron temperature Te to ion temperature Ti is the critical parameter for the presence of two ion-acoustic modes, which should be in the range of 4/ZL(<~)Te/Ti(<~)2AH/ZHAL, where ZL,H are the charge states of light and heavy ions, and AL,H are the atomic numbers of light and heavy ions, respectively. As the temperature ratio varies in this range, the concentration of heavy ions must increase with the ratio Te/Ti so that the two ion-acoustic modes can have the same fluctuation levels.

  1. Rotational manipulation of single cells and organisms using acoustic waves.

    Ahmed, Daniel; Ozcelik, Adem; Bojanala, Nagagireesh; Nama, Nitesh; Upadhyay, Awani; Chen, Yuchao; Hanna-Rose, Wendy; Huang, Tony Jun

    2016-01-01

    The precise rotational manipulation of single cells or organisms is invaluable to many applications in biology, chemistry, physics and medicine. In this article, we describe an acoustic-based, on-chip manipulation method that can rotate single microparticles, cells and organisms. To achieve this, we trapped microbubbles within predefined sidewall microcavities inside a microchannel. In an acoustic field, trapped microbubbles were driven into oscillatory motion generating steady microvortices which were utilized to precisely rotate colloids, cells and entire organisms (that is, C. elegans). We have tested the capabilities of our method by analysing reproductive system pathologies and nervous system morphology in C. elegans. Using our device, we revealed the underlying abnormal cell fusion causing defective vulval morphology in mutant worms. Our acoustofluidic rotational manipulation (ARM) technique is an easy-to-use, compact, and biocompatible method, permitting rotation regardless of optical, magnetic or electrical properties of the sample under investigation. PMID:27004764

  2. Rotational manipulation of single cells and organisms using acoustic waves

    Ahmed, Daniel; Ozcelik, Adem; Bojanala, Nagagireesh; Nama, Nitesh; Upadhyay, Awani; Chen, Yuchao; Hanna-Rose, Wendy; Huang, Tony Jun

    2016-01-01

    The precise rotational manipulation of single cells or organisms is invaluable to many applications in biology, chemistry, physics and medicine. In this article, we describe an acoustic-based, on-chip manipulation method that can rotate single microparticles, cells and organisms. To achieve this, we trapped microbubbles within predefined sidewall microcavities inside a microchannel. In an acoustic field, trapped microbubbles were driven into oscillatory motion generating steady microvortices which were utilized to precisely rotate colloids, cells and entire organisms (that is, C. elegans). We have tested the capabilities of our method by analysing reproductive system pathologies and nervous system morphology in C. elegans. Using our device, we revealed the underlying abnormal cell fusion causing defective vulval morphology in mutant worms. Our acoustofluidic rotational manipulation (ARM) technique is an easy-to-use, compact, and biocompatible method, permitting rotation regardless of optical, magnetic or electrical properties of the sample under investigation. PMID:27004764

  3. Lagrangean formulation of ion- and dust-ion-acoustic waves

    Kourakis, Ioannis; Shukla, Padma Kant

    2004-01-01

    Ion-acoustic modes propagating in unmagnetized dusty plasmas are studied by applying a generic collisionless fluid model. An Eulerian-to-Lagrangean variable transformation leads to a new system of evolution equations, which may be combined into a single (rather complex) equation for the mean ion density. The linear and weakly nonlinear oscillations regimes are studied and their modulational stability is investigated. This study extends known previous results on the Lagrangian description of e...

  4. Detecting nonlinear acoustic waves in liquids with nonlinear dipole optical antennae

    Maksymov, Ivan S

    2015-01-01

    Ultrasound is an important imaging modality for biological systems. High-frequency ultrasound can also (e.g., via acoustical nonlinearities) be used to provide deeply penetrating and high-resolution imaging of vascular structure via catheterisation. The latter is an important diagnostic in vascular health. Typically, ultrasound requires sources and transducers that are greater than, or of order the same size as the wavelength of the acoustic wave. Here we design and theoretically demonstrate that single silver nanorods, acting as optical nonlinear dipole antennae, can be used to detect ultrasound via Brillouin light scattering from linear and nonlinear acoustic waves propagating in bulk water. The nanorods are tuned to operate on high-order plasmon modes in contrast to the usual approach of using fundamental plasmon resonances. The high-order operation also gives rise to enhanced optical third-harmonic generation, which provides an important method for exciting the higher-order Fabry-Perot modes of the dipole...

  5. Phase of acoustic impedance and performance of standing wave thermoacoustic coolers

    Investigations on the relations between the phase angle of the acoustic impedance at the driver piston and the system performance of a standing wave thermoacoustic cooler were performed. The system performance measured at a fixed acoustic power showed that the coefficient of performance of the standing wave thermoacoustic cooler increases as the phase angle increases when the stack temperature span is relatively low. The results were consistent with the simulation results obtained from DELTAE, a computer code based on linear thermoacoustic theory. Analysis on the temperature profiles along the stack showed that the cooling efficiency (COP) of the system could be decreased or increased as the phase angle of the acoustic impedance at the driver piston changes depending on the stack temperature spans

  6. A Novel Bulk Acoustic Wave Resonator for Filters and Sensors Applications

    Zhixin Zhang

    2015-09-01

    Full Text Available Bulk acoustic wave (BAW resonators are widely applied in filters and gravimetric sensors for physical or biochemical sensing. In this work, a new architecture of BAW resonator is demonstrated, which introduces a pair of reflection layers onto the top of a thin film bulk acoustic resonator (FBAR device. The new device can be transformed between type I and type II dispersions by varying the thicknesses of the reflection layers. A computational modeling is developed to fully investigate the acoustic waves and the dispersion types of the device theoretically. The novel structure makes it feasible to fabricate both type resonators in one filter, which offers an effective alternative to improve the pass band flatness in the filter. Additionally, this new device exhibits a high quality factor (Q in the liquid, which opens a possibility for real time measurement in solutions with a superior limitation of detection (LOD in sensor applications.

  7. Resonant attenuation of surface acoustic waves by a disordered monolayer of microspheres

    Eliason, J. K.; Vega-Flick, A.; Hiraiwa, M.; Khanolkar, A.; Gan, T.; Boechler, N.; Fang, N.; Nelson, K. A.; Maznev, A. A.

    2016-02-01

    Attenuation of surface acoustic waves (SAWs) by a disordered monolayer of polystyrene microspheres is investigated. Surface acoustic wave packets are generated by a pair of crossed laser pulses in a glass substrate coated with a thin aluminum film and detected via the diffraction of a probe laser beam. When a 170 μm-wide strip of micron-sized spheres is placed on the substrate between the excitation and detection spots, strong resonant attenuation of SAWs near 240 MHz is observed. The attenuation is caused by the interaction of SAWs with a contact resonance of the microspheres, as confirmed by acoustic dispersion measurements on the microsphere-coated area. Frequency-selective attenuation of SAWs by such a locally resonant metamaterial may lead to reconfigurable SAW devices and sensors, which can be easily manufactured via self-assembly techniques.

  8. High-resolution finite-volume methods for acoustic waves in periodic and random media

    High-resolution numerical methods originally developed for shock capturing in the context of nonlinear conservation laws are found to be very useful for solving acoustics problems in rapidly varying heterogeneous media. These methods are based on solving Riemann problems at the interface between grid cells, which resolve waves into transmitted and reflected components at each interface. The wave-propagation method developed in R. J. LeVeque [J. Comput. Phys. 131, 327 endash 353 (1997)] and implemented in the CLAWPACK software package is tested on several acoustics problems with periodic or random media in one and two space dimensions. A new limiter function is presented for solving problems in a periodic medium where numerical instabilities are observed with standard limiters. copyright 1999 Acoustical Society of America.

  9. Dynamic behavior of microscale particles controlled by standing bulk acoustic waves

    We analyze the dynamic behavior of a spherical microparticle submerged in a fluid medium, driven to the node of a standing bulk acoustic wave created by two opposing transducers. We derive the dynamics of the fluid-particle system taking into account the acoustic radiation force and the time-dependent and time-independent drag force acting on the particle. Using this dynamic model, we characterize the transient and steady-state behavior of the fluid-particle system as a function of the particle and fluid properties and the transducer operating parameters. The results show that the settling time and percent overshoot of the particle trajectory are dependent on the ratio of the acoustic radiation force and time-independent damping force. In addition, we show that the particle oscillates around the node of the standing wave with an amplitude that depends on the ratio of the time-dependent drag forces and the particle inertia.

  10. Horizontal Acoustic Barriers for Protection from Seismic Waves

    Sergey V. Kuznetsov

    2011-01-01

    Full Text Available The basic idea of a seismic barrier is to protect an area occupied by a building or a group of buildings from seismic waves. Depending on nature of seismic waves that are most probable in a specific region, different kinds of seismic barriers can be suggested. Herein, we consider a kind of a seismic barrier that represents a relatively thin surface layer that prevents surface seismic waves from propagating. The ideas for these barriers are based on one Chadwick's result concerning nonpropagation condition for Rayleigh waves in a clamped half-space, and Love's theorem that describes condition of nonexistence for Love waves. The numerical simulations reveal that to be effective the length of the horizontal barriers should be comparable to the typical wavelength.

  11. Anomalous Refraction of Acoustic Guided Waves in Solids with Geometrically Tapered Metasurfaces

    Zhu, Hongfei; Semperlotti, Fabio

    2016-07-01

    The concept of a metasurface opens new exciting directions to engineer the refraction properties in both optical and acoustic media. Metasurfaces are typically designed by assembling arrays of subwavelength anisotropic scatterers able to mold incoming wave fronts in rather unconventional ways. The concept of a metasurface was pioneered in photonics and later extended to acoustics while its application to the propagation of elastic waves in solids is still relatively unexplored. We investigate the design of acoustic metasurfaces to control elastic guided waves in thin-walled structural elements. These engineered discontinuities enable the anomalous refraction of guided wave modes according to the generalized Snell's law. The metasurfaces are made out of locally resonant toruslike tapers enabling an accurate phase shift of the incoming wave, which ultimately affects the refraction properties. We show that anomalous refraction can be achieved on transmitted antisymmetric modes (A0) either when using a symmetric (S0) or antisymmetric (A0) incident wave, the former clearly involving mode conversion. The same metasurface design also allows achieving structure embedded planar focal lenses and phase masks for nonparaxial propagation.

  12. The dynamics of surface acoustic wave-driven scaffold cell seeding.

    Bok, M.H.H.; Li, H.; Yeo, L.Y.; Friend, J.R.

    2009-01-01

    Flow visualization using fluorescent microparticles and cell viability investigations are carried out to examine the mechanisms by which cells are seeded into scaffolds driven by surface acoustic waves. The former consists of observing both the external flow prior to the entry of the suspension into

  13. Kinetic structures of shear Alfven and acoustic wave spectra in burning plasmas

    Zonca, F; Biancalani, A; Chavdarovski, I; Chen, L; Di Troia, C; Wang, X, E-mail: fulvio.zonca@enea.it

    2010-11-01

    We present a general theoretical framework for discussing the physics of low frequency fluctuation spectra of shear Alfven and acoustic waves in toroidal plasmas of fusion interest. This framework helps identifying the relevant dynamics and, thus, interpreting experimental observations. We also discuss the roles of such general theoretical framework for verification and validation of numerical simulation codes vs. analytic predictions and experimental results.

  14. Kinetic structures of shear Alfven and acoustic wave spectra in burning plasmas

    We present a general theoretical framework for discussing the physics of low frequency fluctuation spectra of shear Alfven and acoustic waves in toroidal plasmas of fusion interest. This framework helps identifying the relevant dynamics and, thus, interpreting experimental observations. We also discuss the roles of such general theoretical framework for verification and validation of numerical simulation codes vs. analytic predictions and experimental results.

  15. Cylindrical nebulons, symbolic computation and Baecklund transformation for the cosmic dust acoustic waves

    In a cosmic dusty plasma, the dust-acoustic-wave propagation may be described by a cylindrical Kadomtsev-Petviashvili equation. In this Letter, for such modeling of environments like supernova shells, Saturn's F-ring, etc., cylindrical nebulons and an auto-Baecklund transformation are presented via symbolic computation. Nebulon structures are discussed, and possibly observable effects are proposed for cosmic plasmas

  16. Observations of acoustic-wave-induced superluminescence in an argon plasma

    It is shown that in an argon discharge plasma it is possible to obtain overpopulation of certain electronic levels of atomic argon under the influence of acoustic waves. When the specified threshold is exceeded, then a superluminescence (in the form of light flashes) from the overpopulated electronic levels of atomic argon is observed

  17. Laser Plasmas : Effect of rippled laser beam on excitation of ion acoustic wave

    Nareshpal Singh Saini; Tarsem Singh Gill

    2000-11-01

    Growth of a radially symmetrical ripple, superimposed on a Gaussian laser beam in collisional unmagnetised plasma is investigated. From numerical computation, it is observed that self-focusing of main beam as well as ripple determine the growth dynamics of ripple with the distance of propagation. The effect of growing ripple on excitation of ion acoustic wave (IAW) has also been studied

  18. Ellipsometric and surface acoustic wave sensing of carbon contamination on EUV optics

    Chen, Juequan; Louis, Eric; Bijkerk, Fred; Lee, Chris J.; Wormeester, Herbert; Kunze, Reinhard; Schmidt, Hagen; Schneider, Dieter; Moors, Roel; Schaik, van Willem; Lubomska, Monika; Schellenberg, Frank M.; Fontaine, La Bruno M.

    2009-01-01

    Carbon contamination layers, deposited on extreme ultraviolet (EUV) multilayer mirrors during illumination were characterized ex situ using spectroscopic ellipsometry (SE), laser generated surface acoustic waves (LG-SAW), and by their EUV reflectance loss. We show SE is more sensitive to the deposit

  19. Transmission of wave energy in curved ducts. [acoustic propagation within rigid walls

    Rostafinski, W.

    1974-01-01

    Investigation of the ability of circular bends to transmit acoustic energy flux. A formulation of wave-energy flow is developed for motion in curved ducts. A parametric study over a range of frequencies shows the ability of circular bends to transmit energy in the case of perfectly rigid walls.

  20. Effect of ionic temperature on the modulational instability of ion acoustic waves in a collisionless plasma

    Using the Krylov--Bogoliubov--Mitropolski method, the modulational instability of ion-acoustic waves in a collisionless plasma consisting of isothermal electrons and adiabatic ions is studied. It is found that with the inclusion of ion temperature the modulational instability sets in much earlier

  1. Acoustic microfluidics: Capillary waves and vortex currents in a spherical fluid drop

    Lebedev-Stepanov, P. V.; Rudenko, O. V.

    2016-07-01

    We calculate the radiation forces in a spherical drop lying on a solid substrate. The forces form as a result of the action of a capillary wave on a fluid as it propagates along the free spherical surface. We study the structure of acoustic currents excited by the radiation forces.

  2. Detection and localization of defects in complex structures by Nonlinear Elastic Wave Spectroscopy and Acoustic Emission

    Převorovský, Zdeněk; Chlada, Milan; Krofta, Josef; Kober, Jan; Dos Santos, S.

    Le Mans: The University of Maine in Le Mans, 2013 - (Bentahar, M.; Kenderian, S.; Green, R.). s. 95 [Internanational Symposium on Nondestructive Characterization of Materials /13./. 20.05.2013-24.05.2013, Le Mans] Institutional support: RVO:61388998 Keywords : nonlinear elastic wave spectroscopy * acoustic emission * nondestructive testing * damage initiation * civil structure Subject RIV: JS - Reliability ; Quality Management, Testing

  3. Directional excitation of the designer surface acoustic waves

    Lu, Jiuyang; Qiu, Chunyin; Ke, Manzhu; Liu, Zhengyou

    2015-05-01

    We propose an efficient design route to realize directional excitation of the structure-induced surface waves for airborne sound. The whole system consists of a periodically corrugated rigid plate combining with a pair of asymmetric narrow slits. The directional excitation of the mimicked surface waves stems from the destructive interference between the evanescent waves emitted from the double slits. The directionality can be switched conveniently by tuning the external frequency. The theoretical prediction is validated well by simulations and experiments. Promising applications can be anticipated such as in designing compact devices for airborne sound.

  4. Acoustic Measurement of Surface Wave Damping by a Meniscus.

    Michel, Guillaume; Pétrélis, François; Fauve, Stéphan

    2016-04-29

    We investigate the reflection of gravity-capillary surface waves by a plane vertical barrier. The size of the meniscus is found to strongly affect reflection: the energy of the reflected wave with a pinned contact line is around twice the one corresponding to a fully developed meniscus. To perform these measurements, a new experimental setup similar to an acousto-optic modulator is developed and offers a simple way to measure the amplitude, frequency and direction of propagation of surface waves. PMID:27176523

  5. Numerical simulations of acoustically generated gravitational waves at a first order phase transition

    Hindmarsh, Mark; Huber, Stephan J.; Rummukainen, Kari; Weir, David J.

    2015-12-01

    We present details of numerical simulations of the gravitational radiation produced by a first order thermal phase transition in the early Universe. We confirm that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. We demonstrate that the sound waves have a power spectrum with a power-law form between the scales set by the average bubble separation (which sets the length scale of the fluid flow Lf) and the bubble wall width. The sound waves generate gravitational waves whose power spectrum also has a power-law form, at a rate proportional to Lf and the square of the fluid kinetic energy density. We identify a dimensionless parameter Ω˜GW characterizing the efficiency of this "acoustic" gravitational wave production whose value is 8 π Ω˜GW≃0.8 ±0.1 across all our simulations. We compare the acoustic gravitational waves with the standard prediction from the envelope approximation. Not only is the power spectrum steeper (apart from an initial transient) but the gravitational wave energy density is generically larger by the ratio of the Hubble time to the phase transition duration, which can be 2 orders of magnitude or more in a typical first order electroweak phase transition.

  6. Spin-electron acoustic waves: Linear and nonlinear regimes, and applications

    Andreev, Pavel

    2015-11-01

    Considering the spin-up and spin-down electrons as two different fluids we find corresponding hydrodynamic and kinetic equations from the Pauli equation. We find different pressure the spin-up and spin-down electrons due to different concentrations of electrons in the magnetized electron gas. This difference leads to existence of new branches of linear longitudinal waves propagating with small damping. These waves are called the spin-electron acoustic waves (SEAWs) due to linear dispersion dependence at small wave vectors. We obtain two waves at oblique propagation and one wave at propagation parallel or perpendicular to the external magnetic field. Dispersion dependences of these waves are calculated. Contribution of the Coulomb exchange interaction is included in the model and spectrums. Area of existence of nonlinear SEAWs appearing as a spin-electron acoustic soliton is found for the regime of wave propagation parallel to the external magnetic field. It is obtained that the SEAWs lead to formation of the Cooper pairs. This application of our results to the superconductivity phenomenon reveals in a model of the high-temperature superconductivity with the transition temperatures up to 300 K.

  7. Dust ion-acoustic rogue waves in a three-species ultracold quantum dusty plasmas

    Sun, Wen-Rong; Tian, Bo, E-mail: tian_bupt@163.com; Liu, Rong-Xiang; Liu, De-Yin

    2014-10-15

    Dust ion-acoustic (DIA) rogue waves are reported for a three-component ultracold quantum dusty plasma comprised of inertialess electrons, inertial ions, and negatively charged immobile dust particles. The nonlinear Schrödinger (NLS) equation appears for the low frequency limit. Modulation instability (MI) of the DIA waves is analyzed. Influence of the modulation wave number, ion-to-electron Fermi temperature ratio ρ and dust-to-ion background density ratio N{sub d} on the MI growth rate is discussed. The first- and second-order DIA rogue-wave solutions of the NLS equation are examined numerically. It is found that the enhancement of N{sub d} and carrier wave number can increase the envelope rogue-wave amplitudes. However, the increase of ρ reduces the envelope rogue-wave amplitudes. - Highlights: • The nonlinear Schrödinger equation is derived for the low frequency limit. • Modulational instability growth rate is discussed. • The first- and second-order dust ion-acoustic rogue waves are examined numerically.

  8. OPTIMIZATION OF AN ACOUSTIC LEAKY-WAVE ANTENNA BASED ON ACOUSTIC METAMATERIAL

    Esfahlani, Hussein; Karkar, Sami; Lissek, Hervé

    2013-01-01

    In recent years, an increasing number of pioneering studies have been carried out in the field of acoustic metamaterials, following the path of electromagnetic metamaterials. These artificial engineered materials are designed in such a way so as to achieve new macroscopic properties, like negative refraction, that are not readily present in nature. While the design and the fabrication of these artificial materials is a hot topic among scientists in different fields of physics such as photonic...

  9. Coronal Seismology and the Propagation of Acoustic Waves Along Coronal Loops

    Klimchuk, J A; De Moortel, I

    2004-01-01

    We use a combination of analytical theory, numerical simulation, and data analysis to study the propagation of acoustic waves along coronal loops. We show that the intensity perturbation of a wave depends on a number of factors, including dissipation of the wave energy, pressure and temperature gradients in the loop atmosphere, work action between the wave and a flow, and the sensitivity properties of the observing instrument. In particular, the scale length of the intensity perturbation varies directly with the dissipation scale length (i.e., damping length) and the scale lengths of pressure, temperature, and velocity. We simulate wave propagation in three different equilibrium loop models and find that dissipation and pressure and temperature stratification are the most important effects in the low corona where the waves are most easily detected. Velocity effects are small, and cross-sectional area variations play no direct role for lines-of-sight that are normal to the loop axis. The intensity perturbation...

  10. Topics in Lagrangian and Hamiltonian fluid dynamics: Relabeling symmetry and ion-acoustic wave stability

    Padhye, Nikhil Subhash

    1998-12-01

    Relabeling symmetries of the Lagranian action are found for the ideal, compressible fluid and magnetohydrodynamics (MHD). These give rise to conservation laws of potential vorticity (Ertel's theorem) and helicity in the ideal fluid, cross helicity in MHD, and a conservation law for an ideal fluid with three thermodynamic variables. The symmetry that gives rise to Ertel's theorem is generated by an infinite parameter group, and leads to a generalized Bianchi identity. The existence of a more general symmetry is also shown, with dependence on time and space derivatives of the fields, and corresponds to a family of conservation laws associated with the potential vorticity. In the Hamiltonian formalism, Casimir invariants of the noncanonical formulation are directly constructed from the symmetries of the reduction map from Lagrangian to Eulerian variables. Casimir invariants of MHD include a gauge-dependent family of invariants that incorporates magnetic helicity as a special case. Novel examples of finite dimensional, noncanonical Hamiltonian dynamics are also presented: the equations for a magnetic field line flow with a symmetry direction, and Frenet formulas that describe a curve in 3-space. In the study of Lyapunov stability of ion-acoustic waves, existence of negative energy perturbations is found at short wavelengths. The effect of adiabatic, ionic pressure on ion-acoustic waves is investigated, leading to explicit solitary and nonlinear periodic wave solutions for the adiabatic exponent γ = 3. In particular, solitary waves are found to exist at any wave speed above Mach number one, without an upper cutoff speed. Negative energy perturbations are found to exist despite the addition of pressure, which prevents the establishment of Lyapunov stability, however the stability of ion-acoustic waves is established in the KdV limit, in a manner far simpler than the proof of KdV soliton stability. It is also shown that the KdV free energy (Benjamin, 1972) is recovered

  11. Finite element analysis of true and pseudo surface acoustic waves in one-dimensional phononic crystals

    Graczykowski, B., E-mail: bartlomiej.graczykowski@icn.cat; Alzina, F.; Gomis-Bresco, J. [Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and the Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona (Spain); Sotomayor Torres, C. M. [Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and the Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona (Spain); ICREA—Institucio Catalana de Recerca i Estudis Avançats, 08010 Barcelona (Spain)

    2016-01-14

    In this paper, we report a theoretical investigation of surface acoustic waves propagating in one-dimensional phononic crystal. Using finite element method eigenfrequency and frequency response studies, we develop two model geometries suitable to distinguish true and pseudo (or leaky) surface acoustic waves and determine their propagation through finite size phononic crystals, respectively. The novelty of the first model comes from the application of a surface-like criterion and, additionally, functional damping domain. Exemplary calculated band diagrams show sorted branches of true and pseudo surface acoustic waves and their quantified surface confinement. The second model gives a complementary study of transmission, reflection, and surface-to-bulk losses of Rayleigh surface waves in the case of a phononic crystal with a finite number of periods. Here, we demonstrate that a non-zero transmission within non-radiative band gaps can be carried via leaky modes originating from the coupling of local resonances with propagating waves in the substrate. Finally, we show that the transmission, reflection, and surface-to-bulk losses can be effectively optimised by tuning the geometrical properties of a stripe.

  12. Finite element analysis of true and pseudo surface acoustic waves in one-dimensional phononic crystals

    In this paper, we report a theoretical investigation of surface acoustic waves propagating in one-dimensional phononic crystal. Using finite element method eigenfrequency and frequency response studies, we develop two model geometries suitable to distinguish true and pseudo (or leaky) surface acoustic waves and determine their propagation through finite size phononic crystals, respectively. The novelty of the first model comes from the application of a surface-like criterion and, additionally, functional damping domain. Exemplary calculated band diagrams show sorted branches of true and pseudo surface acoustic waves and their quantified surface confinement. The second model gives a complementary study of transmission, reflection, and surface-to-bulk losses of Rayleigh surface waves in the case of a phononic crystal with a finite number of periods. Here, we demonstrate that a non-zero transmission within non-radiative band gaps can be carried via leaky modes originating from the coupling of local resonances with propagating waves in the substrate. Finally, we show that the transmission, reflection, and surface-to-bulk losses can be effectively optimised by tuning the geometrical properties of a stripe

  13. Generation of tone burst laser ultrasonic waves and its acoustic nonlinearity

    Optical system for generating tone burst ultrasonic wave is introduced and the actual waveform is demonstrated. 4 high power pulse lasers were used for excitation and the stabilized Michelson laser interferometer was used as detection. On the other hand, we tried to investigate the nonlinear acoustic effect of the generated tone burst laser ultrasonic wave. In thermo-elastic region, the nonlinearity did not appear because the absolute amplitude of ultrasonic wave was so small less than 0.5 nm. Whereas, in ablation region, fairly strong nonlinearity appeared because the absolute amplitude of receiving signal was quite large up to about 2 nm.

  14. An undergraduate experiment demonstrating the physics of metamaterials with acoustic waves and soda cans

    Wilkinson, James T.; Whitehouse, Christopher B.; Oulton, Rupert F.; Gennaro, Sylvain D.

    2016-01-01

    We describe a novel undergraduate research project that highlights the physics of metamaterials with acoustic waves and soda cans. We confirm the Helmholtz resonance nature of a single can by measuring its amplitude and phase response to a sound wave. Arranging multiple cans in arrays smaller than the wavelength, we then design an antenna that redirects sound into a preferred direction. The antenna can be thought of as a new resonator, composed of artificially engineered meta-atoms, similar to a metamaterial. These experiments are illustrative, tactile, and open ended so as to enable students to explore the physics of matter/wave interaction.

  15. A normalized wave number variation parameter for acoustic black hole design.

    Feurtado, Philip A; Conlon, Stephen C; Semperlotti, Fabio

    2014-08-01

    In recent years, the concept of the Acoustic Black Hole has been developed as an efficient passive, lightweight absorber of bending waves in plates and beams. Theory predicts greater absorption for a higher thickness taper power. However, a higher taper power also increases the violation of an underlying theory smoothness assumption. This paper explores the effects of high taper power on the reflection coefficient and spatial change in wave number and discusses the normalized wave number variation as a spatial design parameter for performance, assessment, and optimization. PMID:25096139

  16. Collisionless damping of dust-acoustic waves in a charge varying dusty plasma with nonextensive ions

    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.

  17. Characterization of acoustic wave propagation in a concrete member after fire exposure

    Chiang, Chih-Hung; Huang, Chin-Ting

    2001-04-01

    The acoustic wave propagation in a concrete member with embedded reinforcing bars was analyzed. Fire exposure was applied to two batches of concrete specimens prior to acoustic wave characterization. The fire duration and maximum temperature were simulated for experimental studies using a custom-built electric oven. A standard ultrasonic pulse velocity testing system for concrete was used to provide the through-transmission wave propagation. Multiple peaks were found in the frequency domain based on the fast Fourier transform of the waveform. This could be due to cracks induced by the incompatibility of thermal deformation of the constituents of concrete. Further study showed bond deterioration between reinforcing bars and concrete would also contribute to the variation in frequency content of the recorded waveform.

  18. Acoustic wave absorption as a probe of dynamical geometrical response of fractional quantum Hall liquids

    Yang, Kun

    2016-04-01

    We show that an acoustic crystalline wave gives rise to an effect similar to that of a gravitational wave to an electron gas. Applying this idea to a two-dimensional electron gas in the fractional quantum Hall regime, this allows for experimental study of its intra-Landau level dynamical response in the long-wavelength limit. To study such response we generalize Haldane's geometrical description of fractional quantum Hall states to situations where the external metric is time dependent. We show that such time-dependent metric (generated by acoustic wave) couples to collective modes of the system, including a quadrapolar mode at long wavelength, and magnetoroton at finite wavelength. Energies of these modes can be revealed in spectroscopic measurements, controlled by strain-induced Fermi velocity anisotropy. We argue that such geometrical probe provides a potentially highly useful alternative probe of quantum Hall liquids, in addition to the usual electromagnetic response.

  19. Prediction and near-field observation of skull-guided acoustic waves

    Estrada, Héctor; Razansky, Daniel

    2016-01-01

    Ultrasound waves propagating in water or soft biological tissue are strongly reflected when encountering the skull, which limits the use of ultrasound-based techniques in transcranial imaging and therapeutic applications. Current knowledge on the acoustic properties of the cranial bone is restricted to far-field observations, leaving its near-field properties unexplored. We report on the existence of skull-guided acoustic waves, which was herein confirmed by near-field measurements of optoacoustically-induced responses in ex-vivo murine skulls immersed in water. Dispersion of the guided waves was found to reasonably agree with the prediction of a multilayered flat plate model. It is generally anticipated that our findings may facilitate and broaden the application of ultrasound-mediated techniques in brain diagnostics and therapy.

  20. Ion-acoustic solitary waves in ultra-relativistic degenerate pair-ion plasmas

    The arbitrary and the small amplitude ion-acoustic solitary waves (IASWs) have been studied. The former is studied by using the Sagdeev pseudo-potential approach in a plasma consisting of the degenerate ultrarelativistic electrons, positrons, and the non-relativistic classical ions. It is seen that only compressive solitary waves can propagate through such plasmas. The numerical calculations show that the region of existence of the ion-acoustic solitary waves depends upon the positron (ion) number density and the plasma thermal temperature. This study is appropriate for applications in inertial confinement fusion laboratory research as well as the study of astrophysical dense objects such as white dwarf and dense neutron stars.

  1. Electron acoustic waves in a magnetized plasma with kappa distributed ions

    Devanandhan, S.; Lakhina, G. S. [Indian Institute of Geomagnetism, Navi Mumbai (India); Singh, S. V. [Indian Institute of Geomagnetism, Navi Mumbai (India); School of Physics, University of Kwazulu-Natal, Durban (South Africa); Bharuthram, R. [University of the Western Cape, Bellville (South Africa)

    2012-08-15

    Electron acoustic solitary waves in a two component magnetized plasma consisting of fluid cold electrons and hot superthermal ions are considered. The linear dispersion relation for electron acoustic waves is derived. In the nonlinear regime, the energy integral is obtained by a Sagdeev pseudopotential analysis, which predicts negative solitary potential structures. The effects of superthermality, obliquity, temperature, and Mach number on solitary structures are studied in detail. The results show that the superthermal index {kappa} and electron to ion temperature ratio {sigma} alters the regime where solitary waves can exist. It is found that an increase in magnetic field value results in an enhancement of soliton electric field amplitude and a reduction in soliton width and pulse duration.

  2. Acoustic waves in the atmosphere and ground generated by volcanic activity

    This paper reports an interesting sequence of harmonic tremor observed in the 2011 eruption of Shinmoe-dake volcano, southern Japan. The main eruptive activity started with ashcloud forming explosive eruptions, followed by lava effusion. Harmonic tremor was transmitted into the ground and observed as seismic waves at the last stage of the effusive eruption. The tremor observed at this stage had unclear and fluctuating harmonic modes. In the atmosphere, on the other hand, many impulsive acoustic waves indicating small surface explosions were observed. When the effusion stopped and the erupted lava began explosive degassing, harmonic tremor started to be transmitted also to the atmosphere and observed as acoustic waves. Then the harmonic modes became clearer and more stable. This sequence of harmonic tremor is interpreted as a process in which volcanic degassing generates an open connection between the volcanic conduit and the atmosphere. In order to test this hypothesis, a laboratory experiment was performed and the essential features were successfully reproduced.

  3. Acoustic waves in the atmosphere and ground generated by volcanic activity

    Ichihara, Mie; Lyons, John; Oikawa, Jun; Takeo, Minoru [Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Instituto Geofisico, Escuela Politecnica Nacional, Ladron de Guevara E11-253, Aptdo 2759, Quito (Ecuador); Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan)

    2012-09-04

    This paper reports an interesting sequence of harmonic tremor observed in the 2011 eruption of Shinmoe-dake volcano, southern Japan. The main eruptive activity started with ashcloud forming explosive eruptions, followed by lava effusion. Harmonic tremor was transmitted into the ground and observed as seismic waves at the last stage of the effusive eruption. The tremor observed at this stage had unclear and fluctuating harmonic modes. In the atmosphere, on the other hand, many impulsive acoustic waves indicating small surface explosions were observed. When the effusion stopped and the erupted lava began explosive degassing, harmonic tremor started to be transmitted also to the atmosphere and observed as acoustic waves. Then the harmonic modes became clearer and more stable. This sequence of harmonic tremor is interpreted as a process in which volcanic degassing generates an open connection between the volcanic conduit and the atmosphere. In order to test this hypothesis, a laboratory experiment was performed and the essential features were successfully reproduced.

  4. Heat transfer intensification using acoustic waves in a cavity

    The presented paper concerns the idea of using a sound wave to intensify the heat transfer in thermally loaded elements of a gas turbine. The general idea of this type of cooling is described and numerical studies are presented. The applied numerical model is validated based on experimental studies. The research is focused on an improvement in cooling of thermally loaded blade corners. A new concept of the vane internal geometry that improves cooling conditions by generating a sound wave and causing unsteadiness in the flow is compared with the currently used solution. Additionally, a conjugate heat transfer analysis is performed, which allows a better validation of the results. - Highlights: • The idea of using a sound wave to intensify the heat transfer process. • Numerical model and its validation. • Heat transfer assessment based on the fluid flow modelling. • Results of the conjugate heat transfer analysis

  5. Numerical simulations of acoustically generated gravitational waves at a first order phase transition

    Hindmarsh, Mark; Rummukainen, Kari; Weir, David J

    2015-01-01

    We present details of numerical simulations of the gravitational radiation produced by a first order {thermal} phase transition in the early universe. We confirm that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. We demonstrate that the sound waves have a power spectrum with power-law form between the scales set by the average bubble separation (which sets the length scale of the fluid flow $L_\\text{f}$) and the bubble wall width. The sound waves generate gravitational waves whose power spectrum also has a power-law form, at a rate proportional to $L_\\text{f}$ and the square of the fluid kinetic energy density. We identify a dimensionless parameter $\\tilde\\Omega_\\text{GW}$ characterising the efficiency of this "acoustic" gravitational wave production whose value is $8\\pi\\tilde\\Omega_\\text{GW} \\simeq 0.8 \\pm 0.1$ across all our simulations. We compare the acoustic gravitational waves with the standard prediction from the envelope appr...

  6. Guided acoustic and optical waves in silicon-on-insulator for Brillouin scattering and optomechanics

    Sarabalis, Christopher J; Safavi-Naeini, Amir H

    2016-01-01

    We numerically study silicon waveguides on silica showing that it is possible to simultaneously guide optical and acoustic waves in the technologically important silicon on insulator (SOI) material system. Thin waveguides, or fins, exhibit geometrically softened mechanical modes at gigahertz frequencies with phase velocities below the Rayleigh velocity in glass, eliminating acoustic radiation losses. We propose slot waveguides on glass with telecom optical frequencies and strong radiation pressure forces resulting in Brillouin gains on the order of 500 and 50,000 1/(Wm) for backward and forward Brillouin scattering, respectively.

  7. Suppress the Finger Reflection Error of Littlewood-pelay Wavelet Transformation Device of Surface Acoustic Wave

    Li Yuanyuan

    2013-01-01

    Full Text Available In this study, a Wavelet Transformation (WT device of Surface Acoustic Wave (SAW technology is developed on the basis of acoustics, electronics, wavelet theory, applied mathematics and semiconductor planar technology. The Finger Reflection (FR error is the primary reason for this kind of device. To solve the problem, a mathematic model of Littlewood-pelay wavelet was established first, which is matched with the model of SAW. Using the methods of split finger and fake finger to design IDT of Littlewood-pelay WT device of SAW with L-edit software, the FR error can be reduced and the equivalent construction of IDT is simulated.

  8. Free Field Reciprocity Calibration in a Convergent Spherical Acoustic Wave of a Focusing Transducer

    寿文德; 严加勇; 王鸿樟; 钱德初

    2002-01-01

    Based on the reciprocity theorem of the acoustic field, we derive the formula of the reciprocity coefficient of a convergent spherical acoustic wave and we calculate a series of diffraction corrective factor curves of the reciprocity coefficient of transducers. Using these formulae and corrective factors, we calibrate the free field transmitting current response and the free field voltage sensitivity of a focusing transducer using the self-reciprocity method.The experimental results of the reciprocity calibration of the focusing transducer in the frequency range of 2 MHz to 5.4 MHz are presented.

  9. Extremely high Q-factor mechanical modes in quartz bulk acoustic wave resonators at millikelvin temperature

    Goryachev, M.; Creedon, D. L.; Ivanov, E. N.; Tobar, M. E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia); Galliou, S.; Bourquin, R. [Department of Time and Frequency, FEMTO-ST Institute, ENSMM, 26 Chemin de l' Épitaphe, 25000, Besançon (France)

    2014-12-04

    We demonstrate that Bulk Acoustic Wave (BAW) quartz resonator cooled down to millikelvin temperatures are excellent building blocks for hybrid quantum systems with extremely long coherence times. Two overtones of the longitudinal mode at frequencies of 15.6 and 65.4 MHz demonstrate a maximum f.Q product of 7.8×10{sup 16} Hz. With this result, the Q-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained in other mechanical systems. Tested quartz resonators possess the ultra low acoustic losses crucial for electromagnetic cooling to the phonon ground state.

  10. Simulation of an Underwater Acoustic Communication Channel Characterized by Wind-Generated Surface Waves and Bubbles

    Dol, H.S.; Colin, M.E.G.D.; Ainslie, M.A.; Walree, P.A. van; Janmaat, J.

    2012-01-01

    Sea surface scattering by wind-generated waves and bubbles is regarded to be the main non-platform related cause of the time variability of shallow acoustic communication channels. Simulations for predicting the quality of acoustic communication links in such channels thus require adequate modeling of these dynamic sea-surface effects. It is known that, for frequencies in the range 1-4 kHz, the main effect of bubbles on sea surface reflection loss is due to refraction, which can be modeled wi...

  11. Ion-implanted surface-acoustic-wave guides on lithium niobate

    Surface-acoustic-wave guides have been obtained by ion-implanting narrow channels on lithium niobate substrates. Guides of different widths have been tested at 150 MHz. Two doses of helium ions at 100 keV have been used. The acoustic power distribution profiles along a guide length close to 21 mm were determined by optical probing. Air-gap silicon convolvers have been implemented with this kind of guide. An external figure of merit equal to -49 dBm has been measured, whereas without guidance the external figure of merit is only close to -61 dBm for the same transducer pattern

  12. Visualization of Acoustic Waves Propagating within a Single Anisotropic Crystalline Plate

    Chiaki Miyasaka; Kenneth L. Telschow; Jeffry T. Sadler; Roman. Gr. Maev

    2007-04-01

    High frequency acoustic waves propagating within a thin anisotropic plate were imaged using a hybrid system consisting of an acoustic lens (Frequency: 200MHz; Point Focus) for point excitation on one side and a laser displacement interferometer for point detection on the opposite side. The laser beam spot was about 5µm diameter on the surface and the sample was scanned to provide an image of the lateral spatial distribution of the resultant displacement. Theoretical prediction of the resultant displacement was performed using the Angular Spectrum Analysis approach for propagation through the [100] oriented silicon. Comparison of the theoretical predictions with experimental measurements is presented.

  13. SHM based on Acoustic Emission and Nonlinear Elastic Wave Spectroscopy with Time Reversal Mirrors

    Převorovský, Zdeněk; Vejvodová, Šárka; Chlada, Milan; Krofta, Josef

    Drážďany: Fraunhofer Institute for Non-Destructive Testing Dresden Branch (IZFP-D), 2010, s. 1-1. ISBN N. [Dresden Aiport Seminar - Recent Trends in SHM and NDE /5./. Drážďany (DE), 03.11.2010-04.11.2010] R&D Projects: GA MPO(CZ) FR-TI1/274 Institutional research plan: CEZ:AV0Z20760514 Keywords : acoustic emission * nonlinear elastic wave spectroscopy * time reversal mirrors * defect detection * aircraft structural health monitoring Subject RIV: BI - Acoustics www.airportseminar.fraunhofer.de

  14. ST Quartz Acoustic Wave Sensors with Sectional Guiding Layers

    Glen McHale

    2008-07-01

    Full Text Available We report the effect of removing a section of guiding layer from the propagation paths of ST-quartz Love wave sensors; this offers the ease of fabrication of a polymer guiding layer whilst retaining the native surface of the quartz which may then be used for the attachment of a sensitizing layer. Data is presented for the rigid and viscous loading, which indicates a small reduction in mass sensitivity compared to a Love wave device. Biosensing capabilities of these discontinuous ‘sectional’ guiding layer devices are demonstrated using protein adsorption from solution.

  15. ST Quartz Acoustic Wave Sensors with Sectional Guiding Layers

    Glen McHale; Paul Roach; Newton, Michael I.

    2008-01-01

    We report the effect of removing a section of guiding layer from the propagation paths of ST-quartz Love wave sensors; this offers the ease of fabrication of a polymer guiding layer whilst retaining the native surface of the quartz which may then be used for the attachment of a sensitizing layer. Data is presented for the rigid and viscous loading, which indicates a small reduction in mass sensitivity compared to a Love wave device. Biosensing capabilities of these discontinuous ‘section...

  16. Gravitational and acoustic waves in an elastic medium

    Relativistic equations governing perturbations of an elastic medium under the influence of gravitational waves are derived firstly in a gauge-independent way in terms of relative strains, and secondly in terms of gauge-dependent displacements. The derivations are based on the exact nonlinear theory of elasticity in conjunction with Einstein's theory of gravity, and hence are applicable to the solid crusts and cores of neutron stars. It is shown that in the approximately Minkowskian weak-field limit the equations reduce to those derived by previous workers for application in terrestrial contexts such as the detection of gravitational waves by a Weber bar

  17. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    Mitri, F. G.

    2015-12-01

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

  18. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology–ETC, Santa Fe, New Mexico 87508 (United States)

    2015-12-07

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

  19. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries

  20. Resonance Effects of Bilayered Piezoelectric Films Used for Bulk Acoustic Wave Sensors

    ZHANG Hui; ZHANG Shu-Yi; FAN Li

    2011-01-01

    The resonance vibrations of acoustic sensors with two layers of (1120) textured hexagonal piezoelectric films are studied.When the acoustic and electric fields satisfy a special match condition,i.e.the phase variation of thickness shear mode (TSM) at each film equals π,both piezoelectric layers with opposite polarization directions reduce the first TSM and generate the second TSM with higher frequency and a higher quality factor.The excited second TSM can increase the product of the operating frequency and the quality factor,which is useful for improving the mass sensitivity and resolution of acoustic sensors.Additionally,both of the piezoelectric films have larger thickness and decrease the risk of mechanical damage in device production processes.Thin film bulk acoustic sensors have attracted great attention due to their small sizes,low power consumption and high sensitivity,etc.[1] The thickness shear mode (TSM) is more suitable for liquid sensing applications since much less acoustic energy is transferred into the liquid medium than that of longitudinal acoustic waves,due to the fact that ideal liquids cannot support propagations of shear waves.By using a TSM with a high resonance frequency,sensorsbased on thin film bulk acoustic resonator structures can be fabricated by the fixing of a sensitive coating on the surface of the device.[2] The binding events at the sensitive coating can cause a shift of the resonance frequency.[3]%The resonance vibrations of acoustic sensors with two layers of (1120) textured hexagonal piezoelectric films are studied. When the acoustic and electric fields satisfy a special match condition, I.e. The phase variation of thickness shear mode (TSM) at each film equals it, both piezoelectric layers with opposite polarization directions reduce the first TSM and generate the second TSM with higher frequency and a higher quality factor. The excited second TSM can increase the product of the operating frequency and the quality factor, which

  1. Estimation of Shear Wave Velocity in Seafloor Sediment by Seismo-Acoustic Interface Waves:. a Case Study for Geotechnical Application

    Dong, Hefeng; Hovem, Jens M.; Frivik, Svein Arne

    2006-10-01

    Estimates of shear wave velocity profiles in seafloor sediments can be obtained from inversion of measured dispersion relations of seismo-acoustic interface waves propagating along the seabed. The interface wave velocity is directly related to shear wave velocity with value of between 87-96% of the shear wave velocity, dependent on the Poission ratio of the sediments. In this paper we present two different techniques to determine the dispersion relation: a single-sensor method used to determine group velocity and a multi-sensor method used to determine the phase velocity of the interface wave. An inversion technique is used to determine shear wave velocity versus depth and it is based on singular value decomposition and regularization theory. The technique is applied to data acquired at Steinbåen outside Horten in the Oslofjorden (Norway) and compared with the result from independent core measurements taken at the same location. The results show good agreement between the two ways of determining shear wave velocity.

  2. Phase-locked stimulated Brillouin scattering seeded by a transient acoustic wave excited through an optical interference field

    A mathematical description of an experimentally-verified scheme leading to a phase-locked stimulated Brillouin scattering (SBS) is presented. It is shown that this phase-locking of the SBS process may have its origin in a transient acoustic standing wave initiated by an arising optical interference field, eventually leading to a stationary density modulation of the medium. An appropriate solution was obtained by solving the acoustic wave-equation with electrostriction as a driving force. As a consequence of the damping term being included in this equation, the acoustic standing wave becomes gradually attenuated and, contrary to the undamped solution published earlier, thus constitutes a truly transient phenomenon.

  3. Modelling Acoustic Wave Propagation in Axisymmetric Varying-Radius Waveguides

    Bæk, David; Willatzen, Morten

    2008-01-01

    A computationally fast and accurate model (a set of coupled ordinary differential equations) for fluid sound-wave propagation in infinite axisymmetric waveguides of varying radius is proposed. The model accounts for fluid heat conduction and fluid irrotational viscosity. The model problem is solv...

  4. Effects of dissipation on propagation of surface electromagnetic and acoustic waves

    Nagaraj, Nagaraj

    With the recent emergence of the field of metamaterials, the study of subwavelength propagation of plane waves and the dissipation of their energy either in the form of Joule losses in the case of electomagnetic waves or in the form of viscous dissipation in the case of acoustic waves in different interfaced media assumes great importance. With this motivation, I have worked on problems in two different areas, viz., plasmonics and surface acoustics. The first part (chapters 2 & 3) of the dissertation deals with the emerging field of plasmonics. Researchers have come up with various designs in an effort to fabricate efficient plasmonic waveguides capable of guiding plasmonic signals. However, the inherent dissipation in the form of Joule losses limits efficient usage of surface plasmon signal. A dielectric-metal-dielectric planar structure is one of the most practical plasmonic structures that can serve as an efficient waveguide to guide electromagnetic waves along the metal-dielectric boundary. I present here a theoretical study of propagation of surface plasmons along a symmetric dielectric-metal-dielectric structure and show how proper orientation of the optical axis of the anisotropic substrate enhances the propagation length. An equation for propagation length is derived in a wide range of frequencies. I also show how the frequency of coupled surface plasmons can be modulated by changing the thickness of the metal film. I propose a Kronig-Penny model for the plasmonic crystal, which in the long wavelength limit, may serve as a homogeneous dielectric substrate with high anisotropy which do not exist for natural optical crystals. In the second part (chapters 4 & 5) of the dissertation, I discuss an interesting effect of extraordinary absorption of acoustic energy due to resonant excitation of Rayleigh waves in a narrow water channel clad between two metal plates. Starting from the elastic properties of the metal plates, I derive a dispersion equation that gives

  5. Theory of reflection reflection and transmission of electromagnetic, particle and acoustic waves

    Lekner, John

    2016-01-01

    This book deals with the reflection of electromagnetic and particle waves by interfaces. The interfaces can be sharp or diffuse. The topics of the book contain absorption, inverse problems, anisotropy, pulses and finite beams, rough surfaces, matrix methods, numerical methods,  reflection of particle waves and neutron reflection. Exact general results are presented, followed by long wave reflection, variational theory, reflection amplitude equations of the Riccati type, and reflection of short waves. The Second Edition of the Theory of Reflection is an updated and much enlarged revision of the 1987 monograph. There are new chapters on periodically stratified media, ellipsometry, chiral media, neutron reflection and reflection of acoustic waves. The chapter on anisotropy is much extended, with a complete treatment of the reflection and transmission properties of arbitrarily oriented uniaxial crystals. The book gives a systematic and unified treatment reflection and transmission of electromagnetic and particle...

  6. Radiative transfer of acoustic waves in continuous complex media: Beyond the Helmholtz equation

    Baydoun, Ibrahim; Pierrat, Romain; Derode, Arnaud

    2016-01-01

    Heterogeneity can be accounted for by a random potential in the wave equation. For acoustic waves in a fluid with fluctuations of both density and compressibility (as well as for electromagnetic waves in a medium with fluctuation of both permittivity and permeability) the random potential entails a scalar and an operator contribution. For simplicity, the latter is usually overlooked in multiple scattering theory: whatever the type of waves, this simplification amounts to considering the Helmholtz equation with a sound speed $c$ depending on position $\\mathbf{r}$. In this work, a radiative transfer equation is derived from the wave equation, in order to study energy transport through a multiple scattering medium. In particular, the influence of the operator term on various transport parameters is studied, based on the diagrammatic approach of multiple scattering. Analytical results are obtained for fundamental quantities of transport theory such as the transport mean-free path $\\ell^*$, scattering phase functi...

  7. Nonplanar dust acoustic solitary waves in a strongly coupled dusty plasma with superthermal ions

    El-Labany, S. K., E-mail: skellabany@hotmail.com; Zedan, N. A., E-mail: nesreenplasma@yahoo.com [Department of Physics, Faculty of Science, Damietta University, New Damietta, P.O. 34517 Egypt (Egypt); El-Taibany, W. F., E-mail: eltaibany@hotmail.com, E-mail: eltaibany@du.edu.eg [Department of Physics, Faculty of Science, Damietta University, New Damietta, P.O. 34517 Egypt (Egypt); Department of Physics, College of Science for Girls in Abha, King Khalid University, P.O. 960 Abha (Saudi Arabia); El-Shamy, E. F., E-mail: emadel-shamy@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta, P.O. 34517 Egypt (Egypt); Department of Physics, College of Science, King Khalid University, P.O. 9004 Abha (Saudi Arabia)

    2014-12-15

    The nonplanar amplitude modulation of dust acoustic (DA) envelope solitary waves in a strongly coupled dusty plasma (SCDP) has been investigated. By using a reductive perturbation technique, a modified nonlinear Schrödinger equation (NLSE) including the effects of geometry, polarization, and ion superthermality is derived. The modulational instability (MI) of the nonlinear DA wave envelopes is investigated in both planar and nonplanar geometries. There are two stable regions for the DA wave propagation strongly affected by polarization and ion superthermality. Moreover, it is found that the nonlinear DA waves in spherical geometry are the more structurally stable. The larger growth rate of the nonlinear DA MI is observed in the cylindrical geometry. The salient characteristics of the MI in the nonplanar geometries cannot be found in the planar one. The DA wave propagation and the NLSE solutions are investigated both analytically and numerically.

  8. Acoustic-radiation-force-induced shear wave propagation in cardiac tissue

    Bouchard, Richard R.; Wolf, Patrick D.; Hsu, Stephen J.; Dumont, Douglas M.; Trahey, Gregg E.

    2009-02-01

    Shear wave elasticity imaging (SWEI) was employed to track acoustic radiation force (ARF)-induced shear waves in the myocardium of a beating heart. Shear waves were generated in and tracked through the myocardium of the left ventricular free wall (LVFW) in an in vivo heart that was exposed through a thoracotomy; matched studies were also preformed on an ex vivo myocardial specimen. Average shear wave velocities ranged from 2.22 to 2.53 m/s for the ex vivo specimen and 1.5 to 2.9 m/s (1.5-2.09 m/s during diastole; 2.9 m/s during systole) for in vivo specimens. Despite the known rotation of myocardial fiber orientation with tissue depth, there was no statistically significant shear wave velocity depth dependence observed in any of the experimental trials.

  9. Acoustic Pressure Waves in Vibrating 3-D Laminated Beam-Plate Enclosures

    Charles A. Osheku

    2009-01-01

    Full Text Available The effect of structural vibration on the propagation of acoustic pressure waves through a cantilevered 3-D laminated beam-plate enclosure is investigated analytically. For this problem, a set of well-posed partial differential equations governing the vibroacoustic wave interaction phenomenon are formulated and matched for the various vibrating boundary surfaces. By employing integral transforms, a closed form analytical expression is computed suitable for vibroacoustic modeling, design analysis, and general aerospace defensive applications. The closed-form expression takes the form of a kernel of polynomials for acoustic pressure waves showing the influence of linear interface pressure variation across the axes of vibrating boundary surfaces. Simulated results demonstrate how the mode shapes and the associated natural frequencies can be easily computed. It is shown in this paper that acoustic pressure waves propagation are dynamically stable through laminated enclosures with progressive decrement in interfacial pressure distribution under the influence of high excitation frequencies irrespective of whether the induced flow is subsonic, sonic , supersonic, or hypersonic. Hence, in practice, dynamic stability of hypersonic aircrafts or jet airplanes can be further enhanced by replacing their noise transmission systems with laminated enclosures.

  10. On waves in gases. Part I: Acoustics of jets, turbulence, and ducts

    Campos, L. M. B. C.

    1986-01-01

    This review on some aspects of waves in gases concentrates first (Part I) on modern research in the acoustics of fluids at rest or in steady or turbulent motion, in free space, in the presence of obstacles, or in ducts. The study of sound, for which the sole restoring force is pressure, will be extended in a later paper (Part II) to include the other three restoring forces, namely, gravity, electromagnetic, and Coriolis forces, leading to current research on internal, magnetic, and inertial waves and their couplings. The Introduction at the beginning of Part I, and the discussion at the end of Part II, concern all four types of waves in gases, and their relevance in physics and engineering. In Part I, the following areas of acoustics are addressed: the generation of noise by turbulence, inhomogeneities or bubbles, in natural and engineering flows, e.g., wind or jets; the scattering of sound by interfaces and diffraction by turbulence, and their effects on spectral and directional redistribution of energy; propagation in ducts, without or with mean flow, e.g., the horns of musical instruments and loudspeakers, and inlets and exhausts of engines; the effects of dissipation and nonlinearity on waves, e.g., in laboratory and engineering shock tubes, and in geophysical and astrophysical conditions. Underlying these topics is the interaction of acoustics with manking, ranging from the processes of human hearing and speech to the reproduction of desirable sounds (music) and reduction of undesirable sounds (noise).

  11. Capacitive Sensors for the Long-wave Acoustic Radiation by Directed Waves

    L.V. Zaitseva

    2016-06-01

    Full Text Available Consider from the common position present-day state, prospects and the possibility of non-destructive testing capacitive method using. Developed mathematical model of the process of acoustic wave’s excitation (longitudinal and surface with a capacitor allow carrying out the output signal calculation for the subsequent choice of methods and devices for receiving the acoustic oscillations data. A device layout has been developed for realization of capacitive method. The possibility of excitation and reception of acoustic vibrations by capacitive transducers it has been established.

  12. The Frequency and Damping of Ion Acoustic Waves in Collisional and Collisionless Two-species Plasma

    R.L. Berger; E.J. Valeo

    2004-08-18

    The dispersion properties of ion acoustic waves (IAW) are sensitive to the strength of ion-ion collisions in multi-species plasma in which the different species usually have differing charge-to-mass ratios. The modification of the frequency and damping of the fast and slow acoustic modes in a plasma composed of light (low Z) and heavy (high Z) ions is considered. In the fluid limit where the light ion scattering mean free path, {lambda}{sub th} is smaller than the acoustic wavelength, {lambda} = 2{pi}/k, the interspecies friction and heat flow carried by the light ions scattering from the heavy ions causes the damping. In the collisionless limit, k{lambda}{sub th} >> 1, Landau damping by the light ions provides the dissipation. In the intermediate regime when k{lambda}{sub th} {approx} 1, the damping is at least as large as the sum of the collisional and Landau damping.

  13. Depolarized guided acoustic wave Brillouin scattering in hollow-core photonic crystal fibers

    Zhong, Wenjia Elser née; Elser, Dominique; Heim, Bettina; Marquardt, Christoph; Leuchs, Gerd

    2015-01-01

    By performing quantum-noise-limited optical heterodyne detection, we observe polarization noise in light after propagation through a hollow-core photonic crystal fiber (PCF). We compare the noise spectrum to the one of a standard fiber and find an increase of noise even though the light is mainly transmitted in air in a hollow-core PCF. Combined with our simulation of the acoustic vibrational modes in the hollow-core PCF, we are offering an explanation for the polarization noise with a variation of guided acoustic wave Brillouin scattering (GAWBS). Here, instead of modulating the strain in the fiber core as in a solid core fiber, the acoustic vibrations in hollow-core PCF influence the effective refractive index by modulating the geometry of the photonic crystal structure. This induces polarization noise in the light guided by the photonic crystal structure.

  14. Schlieren imaging of the standing wave field in an ultrasonic acoustic levitator

    Rendon, Pablo Luis; Boullosa, Ricardo R.; Echeverria, Carlos; Porta, David

    2015-11-01

    We consider a model of a single axis acoustic levitator consisting of two cylinders immersed in air and directed along the same axis. The first cylinder has a flat termination and functions as a sound emitter, and the second cylinder, which is simply a refector, has the side facing the first cylinder cut out by a spherical surface. By making the first cylinder vibrate at ultrasonic frequencies a standing wave is produced in the air between the cylinders which makes it possible, by means of the acoustic radiation pressure, to levitate one or several small objects of different shapes, such as spheres or disks. We use schlieren imaging to observe the acoustic field resulting from the levitation of one or several objects, and compare these results to previous numerical approximations of the field obtained using a finite element method. The authors acknowledge financial support from DGAPA-UNAM through project PAPIIT IN109214.

  15. Excitation and detection of shear horizontal waves with electromagnetic acoustic transducers for nondestructive testing of plates

    Ma, Qingzeng; Jiao, Jingpin; Hu, Ping; Zhong, Xi; Wu, Bin; He, Cunfu

    2014-03-01

    The fundamental shear horizontal(SH0) wave has several unique features that are attractive for long-range nondestructive testing(NDT). By a careful design of the geometric configuration, electromagnetic acoustic transducers(EMATs) have the capability to generate a wide range of guided wave modes, such as Lamb waves and shear-horizontal(SH) waves in plates. However, the performance of EMATs is influenced by their parameters. To evaluate the performance of periodic permanent magnet(PPM) EMATs, a distributed-line-source model is developed to calculate the angular acoustic field cross-section in the far-field. Numerical analysis is conducted to investigate the performance of such EMATs with different geometric parameters, such as period and number of magnet arrays, and inner and outer coil widths. Such parameters have a great influence on the directivity of the generated SH0 waves that arises mainly in the amplitude and width of both main and side lobes. According to the numerical analysis, these parameters are optimized to obtain better directivity. Optimized PPM EMATs are designed and used for NDT of strip plates. Experimental results show that the lateral boundary of the strip plate has no perceivable influence on SH0-wave propagation, thus validating their used in NDT. The proposed model predicts the radiation pattern of PPM EMATs, and can be used for their parameter optimization.

  16. The effects of fracture permeability on acoustic wave propagation in the porous media: A microscopic perspective.

    Wang, Ding; Wang, Liji; Ding, Pinbo

    2016-08-01

    An illustrative theory is developed to analyze the acoustic wave propagation characteristics in the porous media with anisotropic permeability. We focus here on the role of fracture permeability in the unconsolidated porous media, looking in particular at the compressional P-wave phase velocity and attenuation. Two fluid pressure equilibration characteristic time factors are defined, which are corresponding to crack-pore system and crack-crack system, respectively. The theoretical results show that the dispersion and attenuation characteristics of acoustic wave are affected by porous matrix and fracture permeability simultaneously. Due to the fluid exchange that takes place between fractures and pores dominantly, the influence of the fracture connectivity on the wave propagation is very weak when the permeability of background medium is relatively high. However, correlation between wave propagation and fracture permeability is significant when the matrix permeability at a low level. A second attenuation peak occurs for the fluid flow within fractures in high-frequency region for more and more higher fracture permeability. The exact analytical solutions that are compared to numerical forward modeling of wave propagation in fractured media allow us to verify the correctness of the new model. If there exists another approach for obtaining the connectivity information of background media, we can use this model to analyze qualitatively the permeability of fractures or afford an indicator of in-situ permeability changes in a oil reservoir, for example, fracturing operations. PMID:27259119

  17. Effects of acoustic waves on stick-slip in granular media and implications for earthquakes

    Johnson, P.A.; Savage, H.; Knuth, M.; Gomberg, J.; Marone, C.

    2008-01-01

    It remains unknown how the small strains induced by seismic waves can trigger earthquakes at large distances, in some cases thousands of kilometres from the triggering earthquake, with failure often occurring long after the waves have passed. Earthquake nucleation is usually observed to take place at depths of 10-20 km, and so static overburden should be large enough to inhibit triggering by seismic-wave stress perturbations. To understand the physics of dynamic triggering better, as well as the influence of dynamic stressing on earthquake recurrence, we have conducted laboratory studies of stick-slip in granular media with and without applied acoustic vibration. Glass beads were used to simulate granular fault zone material, sheared under constant normal stress, and subject to transient or continuous perturbation by acoustic waves. Here we show that small-magnitude failure events, corresponding to triggered aftershocks, occur when applied sound-wave amplitudes exceed several microstrain. These events are frequently delayed or occur as part of a cascade of small events. Vibrations also cause large slip events to be disrupted in time relative to those without wave perturbation. The effects are observed for many large-event cycles after vibrations cease, indicating a strain memory in the granular material. Dynamic stressing of tectonic faults may play a similar role in determining the complexity of earthquake recurrence. ??2007 Nature Publishing Group.

  18. Laser-generated thermoelastic acoustic sources and acoustic waves in anisotropic plate

    XU BaiQiang; WANG Feng; FENG Jun; WANG JiJun; SUN HongXiang; LUO Ying

    2009-01-01

    The effect of anisotropy on the ultrasound wave generation and propagation in the unidirectional fi-ber-reinforced composite plate has been investigated. A quantitative numerical model for the la-ser-generated ultrasound in the thermoelastic regime was presented by using a finite element method.All factors, such as spatial and time distributions of the incident laser beam, optical penetration, ther-mal diffusivity, and source-receiver distance can be taken into account. Numerical results show that the effect on ultrasound waveform of the size of the laser volume source produces strong bipolar Iongitu-dinal waves and improves the amplitude and directivity of the longitudinal waves. A fiber-reinforced composite material exhibits isotropic or homogenous behavior for ultrasonic wave propagation per-pendicular to the fiber direction. For ultrasonic propagation along the fiber direction, ultrasonic dis-persion resulting from the inhomogeneous nature of the material affects the laser ultrasonic waveforms. As the dimensions of the laser pulse are increased in space and time, the displacement waveform be-comes broader and its magnitude decreases.

  19. Laser-generated thermoelastic acoustic sources and acoustic waves in anisotropic plate

    2009-01-01

    The effect of anisotropy on the ultrasound wave generation and propagation in the unidirectional fi- ber-reinforced composite plate has been investigated. A quantitative numerical model for the la- ser-generated ultrasound in the thermoelastic regime was presented by using a finite element method. All factors, such as spatial and time distributions of the incident laser beam, optical penetration, ther- mal diffusivity, and source-receiver distance can be taken into account. Numerical results show that the effect on ultrasound waveform of the size of the laser volume source produces strong bipolar longitu- dinal waves and improves the amplitude and directivity of the longitudinal waves. A fiber-reinforced composite material exhibits isotropic or homogenous behavior for ultrasonic wave propagation per- pendicular to the fiber direction. For ultrasonic propagation along the fiber direction, ultrasonic dis- persion resulting from the inhomogeneous nature of the material affects the laser ultrasonic waveforms. As the dimensions of the laser pulse are increased in space and time, the displacement waveform be- comes broader and its magnitude decreases.

  20. Structure design on SH wave electromagnetic acoustic transducer (EMAT)

    EMAT is being used for the volume inspection under high temperature environment in the neighborhood ISI (In Service Inspection) of MONJU reactor vessel. In order to improve the operability and durability of ISI instruments, the weight halving of the inspection robot is required. In this connection, it becomes necessary and important to lighten some related assemblies of EMAT. In the present research, along with the light weightization of SH wave EMAT, the feasibility to reduce the weight of general magnet structure in accordance with the characterization of magnetic flux density distributions is analyzed. In addition, it is found that the Halbach magnet arrangement can be used as a magnet structure of SH wave EMAT. Numerical simulation of a static magnetic field analysis is employed for characterizing the magnetic properties of the general magnet structure of SH wave EMAT, and the Halbach magnet arrangement. The magnetic flux density distributions in both structures are compared with each other to search for a more powerful magnet structure. It is noticed that the magnetic properties of magnet structure are analyzed only at room temperature in this report. The main analysis result are summarized as follows: 1. Halbach magnet arrangement can be used as a magnet structure of SH wave EMAT. 2. Halbach magnet arrangement has a more powerful magnetic flux density distribution than that for the general magnet structure. In the case of a magnet arrangement with 2.5 mm half-period, the maximum value of magnetic flux density along the normal direction in the Halbach magnet arrangement (magnet thickness a=b=1.25 mm) can be as large as 1.6 times of that in the general magnet structure. In other words, by using Halbach magnet arrangement, a powerful SH wave EMAT can be composed comparing with the general magnet structure, even if nearly the same amount of magnet is used. 3. The dependence of the magnetic flux density along the normal direction on the magnet height dimension L

  1. Tunable arrayed waveguide grating driven by surface acoustic waves

    Crespo-Poveda, Antonio; Hernández-Mínguez, Alberto; Biermann, Klaus; Tahraoui, Abbes; Gargallo, Bernardo; Muñoz, Pascual; Santos, Paulo V.; Cantarero, Andrés.; de Lima, Maurício M.

    2016-03-01

    We present a design approach for compact reconfigurable phased-array wavelength-division multiplexing (WDM) devices with N access waveguides (WGs) based on multimode interference (MMI) couplers. The proposed devices comprise two MMI couplers which are employed as power splitters and combiners, respectively, linked by an array of N single-mode WGs. First, passive devices are explored. Taking advantage of the transfer phases between the access ports of the MMI couplers, we derive very simple phase relations between the arms that provide wavelength dispersion at the output plane of the devices. When the effective refractive index of the WGs is modulated with the proper relative optical phase difference, each wavelength component can switch paths between the preset output channel and the remaining output WGs. Moreover, very simple phase relations between the modulated WGs that enable the reconfiguration of the output channel distribution when the appropriated coupling lengths of the MMI couplers are chosen are also derived. In this way, a very compact expression to calculate the channel assignment of the devices as a function of the applied phase shift is derived for the general case of N access WGs. Finally, the experimental results corresponding to an acoustically driven phased-array WDM device with five access WGs fabricated on (Al,Ga)As are shown.

  2. Temperature dependence of acoustic harmonics generated by nonlinear ultrasound wave propagation in water at various frequencies.

    Maraghechi, Borna; Hasani, Mojtaba H; Kolios, Michael C; Tavakkoli, Jahan

    2016-05-01

    Ultrasound-based thermometry requires a temperature-sensitive acoustic parameter that can be used to estimate the temperature by tracking changes in that parameter during heating. The objective of this study is to investigate the temperature dependence of acoustic harmonics generated by nonlinear ultrasound wave propagation in water at various pulse transmit frequencies from 1 to 20 MHz. Simulations were conducted using an expanded form of the Khokhlov-Zabolotskaya-Kuznetsov nonlinear acoustic wave propagation model in which temperature dependence of the medium parameters was included. Measurements were performed using single-element transducers at two different transmit frequencies of 3.3 and 13 MHz which are within the range of frequencies simulated. The acoustic pressure signals were measured by a calibrated needle hydrophone along the axes of the transducers. The water temperature was uniformly increased from 26 °C to 46 °C in increments of 5 °C. The results show that the temperature dependence of the harmonic generation is different at various frequencies which is due to the interplay between the mechanisms of absorption, nonlinearity, and focusing gain. At the transmit frequencies of 1 and 3.3 MHz, the harmonic amplitudes decrease with increasing the temperature, while the opposite temperature dependence is observed at 13 and 20 MHz. PMID:27250143

  3. Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies.

    Tadesse, Semere Ayalew; Li, Mo

    2014-01-01

    Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally, these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acousto-optic coupling in nanophotonic devices. Here we demonstrate microwave frequency surface acoustic wave transducers co-integrated with nanophotonic resonators on piezoelectric aluminum nitride substrates. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength is achieved. The phase and modal matching conditions in this scheme are investigated for efficient modulation. The new acousto-optic platform can lead to novel optical devices based on nonlinear Brillouin processes and provides a direct, wideband link between optical and microwave photons for microwave photonics and quantum optomechanics. PMID:25400144

  4. Angular oscillation of solid scatterers in response to progressive planar acoustic waves: do fish otoliths rock?

    Krysl, Petr; Hawkins, Anthony D; Schilt, Carl; Cranford, Ted W

    2012-01-01

    Fish can sense a wide variety of sounds by means of the otolith organs of the inner ear. Among the incompletely understood components of this process are the patterns of movement of the otoliths vis-à-vis fish head or whole-body movement. How complex are the motions? How does the otolith organ respond to sounds from different directions and frequencies? In the present work we examine the responses of a dense rigid scatterer (representing the otolith) suspended in an acoustic fluid to low-frequency planar progressive acoustic waves. A simple mechanical model, which predicts both translational and angular oscillation, is formulated. The responses of simple shapes (sphere and hemisphere) are analyzed with an acoustic finite element model. The hemispherical scatterer is found to oscillate both in the direction of the propagation of the progressive waves and also in the plane of the wavefront as a result of angular motion. The models predict that this characteristic will be shared by other irregularly-shaped scatterers, including fish otoliths, which could provide the fish hearing mechanisms with an additional component of oscillation and therefore one more source of acoustical cues. PMID:22912710

  5. Characterization of compressed earth blocks using low frequency guided acoustic waves.

    Ben Mansour, Mohamed; Ogam, Erick; Fellah, Z E A; Soukaina Cherif, Amel; Jelidi, Ahmed; Ben Jabrallah, Sadok

    2016-05-01

    The objective of this work was to analyze the influence of compaction pressure on the intrinsic acoustic parameters (porosity, tortuosity, air-flow resistivity, viscous, and thermal characteristic lengths) of compressed earth blocks through their identification by solving an inverse acoustic wave transmission problem. A low frequency acoustic pipe (60-6000 Hz of length 22 m, internal diameter 3.4 cm) was used for the experimental characterization of the samples. The parameters were identified by the minimization of the difference between the transmissions coefficients data obtained in the pipe with that from an analytical interaction model in which the compressed earth blocks were considered as having rigid frames. The viscous and thermal effects in the pores were accounted for by employing the Johnson-Champoux-Allard-Lafarge model. The results obtained by inversion for high-density compressed earth blocks showed some discordance between the model and experiment especially for the high frequency limit of the acoustic characteristics studied. This was as a consequence of applying high compaction pressure rendering them very highly resistive therefore degrading the signal-to-noise ratios of the transmitted waves. The results showed that the airflow resistivity was very sensitive to the degree of the applied compaction pressure used to form the blocks. PMID:27250150

  6. Traveling wave tube measurements for low-frequency properties of underwater acoustic materials

    2007-01-01

    A traveling wave tube measurement technique for measuring acoustic properties of underwater acoustic materials was developed. Water temperature and pressure environments of the ocean can be simulated in a water-filled tube, and the acoustic parameters of samples of underwater acoustic materials are measured in the range of low-frequency. A tested sample is located at central position of the tube. A pair of projectors is separately located at both ends of the tube. Using an active anechoic technique, the sound wave transmitting the tested sample is hardly reflected by the surface of secondary transducer. So the traveling sound field is built up in the tube. By separately calculating the transfer functions of every pair of double hydrophones in the sound fields from the both sides of the sample, its reflection coefficients and transmission coefficients are obtained. In the measurement system, the inside diameter of the tube is Φ208 mm, the working frequency range is from 100 to 4000 Hz, the maximum pressure is 5 MPa. The reflection coefficients and transmission coefficients of a water layer and a stainless steel layer samples are measured actually and calculated theoretically. The results show that the measured values are in good agreement with the values calculated, and the measurement uncertainty is not greater than 1.5 dB.

  7. Modulation instability and ion-acoustic rogue waves in a strongly coupled collisional plasma with nonthermal nonextensive electrons

    Guo, Shimin; Mei, Liquan; He, Yaling; Li, Ying

    2016-02-01

    The nonlinear propagation of ion-acoustic waves is theoretically reported in a collisional plasma containing strongly coupled ions and nonthermal electrons featuring Tsallis distribution. For this purpose, the nonlinear integro-differential form of the generalized hydrodynamic model is used to investigate the strong-coupling effect. The modified complex Ginzburg-Landau equation with a linear dissipative term is derived for the potential wave amplitude in the hydrodynamic regime, and the modulation instability of ion-acoustic waves is examined. When the dissipative effect is neglected, the modified complex Ginzburg-Landau equation reduces to the nonlinear Schrödinger equation. Within the unstable region, two different types of second-order ion-acoustic rogue waves including single peak type and rogue wave triplets are discussed. The effect of the plasma parameters on the rogue waves is also presented.

  8. Design and Fabrication of Acoustic Wave Actuated Microgenerator for Portable Electronic Devices

    Lai, Tenghsien; Tsou, Chingfu

    2008-01-01

    The past few years have seen an increasing focus on energy harvesting issue, including power supply for portable electric devices. Utilize scavenging ambient energy from the environment could eliminate the need for batteries and increase portable device lifetimes indefinitely. In addition, through MEMS technology fabricated micro-generator could easy integrate with these small or portable devices. Several different ambient sources, including solar, vibration and temperature effect, have already exploited [1-3]. Each energy source should be used in suitable environment, therefore to produce maximum efficiency. In this paper, we present an acoustic wave actuated micro-generator for power system by using the energy of acoustic waves, such as the sound from human voices or speakerphone, to actuate a MEMS-type electromagnetic transducer. This provides a longer device lifetime and greater power system convenience. Moreover, it is convenient to integrate MEMS-based microgenerators with small or porta le devices

  9. Surface acoustic wave regulated single photon emission from a coupled quantum dot-nanocavity system

    Weiß, Matthias; Reichert, Thorsten; Finley, Jonathan J; Wixforth, Achim; Kaniber, Michael; Krenner, Hubert J

    2016-01-01

    A coupled quantum dot--nanocavity system in the weak coupling regime of cavity quantumelectrodynamics is dynamically tuned in and out of resonance by the coherent elastic field of a $f_{\\rm SAW}\\simeq800\\,\\mathrm{MHz}$ surface acoustic wave. When the system is brought to resonance by the sound wave, light-matter interaction is strongly increased by the Purcell effect. This leads to a precisely timed single photon emission as confirmed by the second order photon correlation function $g^{(2)}$. All relevant frequencies of our experiment are faithfully identified in the Fourier transform of $g^{(2)}$, demonstrating high fidelity regulation of the stream of single photons emitted by the system. The implemented scheme can be directly extended to strongly coupled systems and acoustically drives non-adiabatic entangling quantum gates based on Landau-Zener transitions.

  10. Wireless surface acoustic wave sensors for displacement and crack monitoring in concrete structures

    Perry, M.; McKeeman, I.; Saafi, M.; Niewczas, P.

    2016-03-01

    In this work, we demonstrate that wireless surface acoustic wave devices can be used to monitor millimetre displacements in crack opening during the cyclic and static loading of reinforced concrete structures. Sensors were packaged to extend their gauge length and to protect them against brittle fracture, before being surface-mounted onto the tensioned surface of a concrete beam. The accuracy of measurements was verified using computational methods and optical-fibre strain sensors. After packaging, the displacement and temperature resolutions of the surface acoustic wave sensors were 10 μ {{m}} and 2 °C respectively. With some further work, these devices could be retrofitted to existing concrete structures to facilitate wireless structural health monitoring.

  11. Surface acoustic waves and elastic constants of InN epilayers determined by Brillouin scattering

    Jimenez-Rioboo, R.J.; Prieto, C. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, Madrid (Spain); Cusco, R.; Domenech-Amador, N.; Artus, L. [Institut Jaume Almera, Consell Superior d' Investigacions Cientifiques (CSIC), Lluis Sole i Sabaris s.n., Barcelona, Catalonia (Spain); Yamaguchi, T.; Nanishi, Y. [Faculty of Science and Engineering, Ritsumeikan University, Noji-Higashi, Kusatsu, Shiga (Japan)

    2012-06-15

    The surface acoustic wave velocity in InN has been experimentally determined by means of Brillouin scattering experiments on c - and m -face epilayers. From simulations based on the Green's function formalism we determine the shear elastic constants c{sub 66} and c{sub 44} and propose a complete set of elastic constants for wurtzite InN. The analysis of the sagittal and azimuthal dependence of the surface acoustic wave velocity indicates a slightly different elastic behavior of the m -face sample that basically affects the c{sub 44} elastic constant. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Intrinsically tunable bulk acoustic wave resonators based on sol-gel grown PMN-PT films

    Vorobiev, A.; Spreitzer, M.; Veber, A.; Suvorov, D.; Gevorgian, S.

    2014-08-01

    Intrinsically tunable bulk acoustic wave resonators, based on sol-gel 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PMN-PT) thin films, with high effective electromechanical coupling coefficient of 13% and tunability of the series resonance frequency up to 4.0% are fabricated and characterized. The enhanced electroacoustic properties of the PMN-PT resonators are attributed to the mechanism of polarization rotation occurring in the region of the morphotropic phase boundary. Electroacoustic performance of the PMN-PT resonators is analyzed using the theory of dc field-induced piezoelectric effect in ferroelectrics. Extrinsic acoustic loss in the PMN-PT resonators is analyzed using the model of the wave scattering at reflections from rough interfaces. Mechanical Q-factor of the resonators is up to 70 at 4.1 GHz and limited mainly by losses in the PMN-PT film.

  13. Longitudinal acoustic waves in layered media: Comparative study of Raman scattering and reflection delay time

    El Boudouti, E H; Zelmat, R; Bailich, R [LDOM, Departement de Physique, Faculte des Sciences, Universite Mohamed I, 60000 Oujda (Morocco); Hassouani, Y El [Universite de Bordeaux, Laboratoire de Mecanique Physique, Talence F-33405 (France); Djafari-Rouhani, B, E-mail: elboudouti@yahoo.f [Institut d' Electronique, de Microelectronique et de Nanotechnologie, UMR CNRS 8520, UFR de Physique, Universite de Lille 1, 59655 Villeneuve d' Ascq (France)

    2010-03-01

    Using a Green's function method, we present a theoretical analysis of the propagation of acoustic waves in multilayer structures. The structure studied consists of a finite superlattice (SL) made of a periodic repetition of N unit cells deposited on a substrate. Such a structure exhibits extended modes constituting the allowed bands separated by forbidden bands where localized modes associated to free surfaces, defect layers, ... may exist. These modes can be observed either by Raman scattering when an incident light is launched from vacuum towards the multilayer, or by the reflection delay time when an incident acoustic wave is launched from the substrate. Specific applications of our results are given for some available experiments in the literature (e.g., Si/Ge{sub x}Si{sub 1-x}, GaSb-AlSb) and a good agreement has been obtained between our theoretical results and the experimental data.

  14. Effect of ion viscosity on dust ion-acoustic shock waves in a nonextensive magnetoplasma

    El-Tantawy, S. A.

    2016-08-01

    The nonlinear features of dust ion-acoustic shock waves (DIASWs) in a magnetoplasma containing cold positive ions, nonextensive electrons, and immobile negatively charged dust grains taking into account the cold ion kinematic viscosity are investigated. The reductive perturbation technique is used to derive a Zakharov-Kuznetsov-Burgers (ZK-Burgers). It is found that the fundamental properties of the DIASWs are significantly modified by the different system parameters such as the nonextensive parameter, the ion gyrofrequency, the dust concentration, the viscosity parameter, and the direction cosines. Also, the polarities (positive and negative shocks) of the potential are found to exist in the plasma under consideration. The implications of our results may be used in understanding the acoustic shock waves propagation in laboratory and space plasmas.

  15. Longitudinal acoustic waves in layered media: Comparative study of Raman scattering and reflection delay time

    Using a Green's function method, we present a theoretical analysis of the propagation of acoustic waves in multilayer structures. The structure studied consists of a finite superlattice (SL) made of a periodic repetition of N unit cells deposited on a substrate. Such a structure exhibits extended modes constituting the allowed bands separated by forbidden bands where localized modes associated to free surfaces, defect layers, ... may exist. These modes can be observed either by Raman scattering when an incident light is launched from vacuum towards the multilayer, or by the reflection delay time when an incident acoustic wave is launched from the substrate. Specific applications of our results are given for some available experiments in the literature (e.g., Si/GexSi1-x, GaSb-AlSb) and a good agreement has been obtained between our theoretical results and the experimental data.

  16. Visualization of short surface acoustic waves by stroboscopic x-ray topography: analysis of contrast

    In this paper the capabilities of stroboscopic x-ray topography to visualize the propagation of short (3 crystals under SAW excitation were carried out at the ID19 beam line of the European synchrotron radiation facility. The developed theoretical analysis of the SAW-induced contrast in Bragg scattering geometry helped to optimize experimental conditions and receive high quality images with well-resolved individual acoustic wave fronts. The basic contrast mechanism is related to the SAW-induced corrugation of atomic planes that causes the focusing of x-rays. The focal distance is directly proportional to the SAW wavelength and inversely proportional to the deformation amplitude at the crystal surface. Simulations of diffraction contrast allowed us to conclude that the best contrast is achieved when the acoustic wave vector is perpendicular to the x-ray scattering plane and the sample/film distance equals 2-4 focal distances

  17. Field theory for zero sound and ion acoustic wave in astrophysical matter

    Gabadadze, Gregory; Rosen, Rachel A.

    2016-02-01

    We set up a field theory model to describe the longitudinal low-energy modes in high density matter present in white dwarf stars. At the relevant scales, ions—the nuclei of oxygen, carbon, and helium—are treated as heavy pointlike spin-0 charged particles in an effective field theory approach, while the electron dynamics is described by the Dirac Lagrangian at the one-loop level. We show that there always exists a longitudinal gapless mode in the system irrespective of whether the ions are in a plasma, crystal, or quantum liquid state. For certain values of the parameters, the gapless mode can be interpreted as a zero sound mode and, for other values, as an ion acoustic wave; we show that the zero sound and ion acoustic wave are complementary to each other. We discuss possible physical consequences of these modes for properties of white dwarfs.

  18. Field Theory for Zero Sound and Ion Acoustic Wave in Astrophysical Matter

    Gabadadze, Gregory

    2015-01-01

    We set up a field theory model to describe the longitudinal low energy modes in high density matter present in white dwarf stars. At the relevant scales, ions -- the nuclei of oxygen, carbon and helium -- are treated as heavy point-like spin-0 charged particles in an effective field theory approach, while the electron dynamics is described by the Dirac Lagrangian at the one-loop level. We show that there always exists a longitudinal gapless mode in the system irrespective whether the ions are in a plasma, crystal, or quantum liquid state. For certain values of the parameters, the gapless mode can be interpreted as a zero sound mode and, for other values, as an ion acoustic wave; we show that the zero sound and ion acoustic wave are complementary to each other. We discuss possible physical consequences of these modes for properties of white dwarfs.

  19. Evidence for short-period acoustic waves in the solar atmosphere

    Wunnenberg, M.; Kneer, F.; Hirzberger, J.

    2002-11-01

    Short-period acoustic waves are thought to supply the energy for the radiative losses of the non-magnetic chromosphere of the Sun and, in general, of late-type stars. Here, we present evidence for the existence of waves in the solar atmosphere with periods in the range of 50 s Tower Telescope at the Observatorio del Teide/Tenerife. They are subjected to speckle reconstruction and to a wavelet analysis. The atmospheric ranges forming the velocity signals are narrowed by linear combinations of Doppler maps from wavelengths near line center. The power in the short-period range is concentrated above intergranular spaces. We estimate an acoustic flux into the chromosphere of approximately 3*E6 erg cm-2 s-1, as needed for the chromospheric radiative losses.

  20. Imaging of transient surface acoustic waves by full-field photorefractive interferometry

    Xiong, Jichuan [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China); School of Electronic and Optical Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei, Nanjing 210094 (China); Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Heverlee (Belgium); Xu, Xiaodong, E-mail: xdxu@nju.edu.cn, E-mail: christ.glorieux@fys.kuleuven.be [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China); Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Heverlee (Belgium); Glorieux, Christ, E-mail: xdxu@nju.edu.cn, E-mail: christ.glorieux@fys.kuleuven.be [Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Heverlee (Belgium); Matsuda, Osamu [Division of Applied Physics, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Cheng, Liping [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China)

    2015-05-15

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz.

  1. Imaging of transient surface acoustic waves by full-field photorefractive interferometry

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz

  2. Spin-electron acoustic waves: The Landau damping and ion contribution in the spectrum

    Andreev, Pavel A.

    2016-06-01

    Separated spin-up and spin-down quantum kinetics is derived for more detailed research of the spin-electron acoustic waves (SEAWs). This kinetic theory allows us to obtain the spectrum of the SEAWs including the effects of occupation of quantum states more accurately than the quantum hydrodynamic theory. We derive and apply the quantum kinetic theory to calculate the Landau damping of the SEAWs. We consider the contribution of ions dynamics into the SEAW spectrum. We obtain the contribution of ions in the Landau damping in the temperature regime of classic ions. Kinetic analysis for the ion-acoustic, zero sound, and Langmuir waves at the separated spin-up and spin-down electron dynamics is presented as well.

  3. Frequency modulation at a moving material interface and a conservation law for wave number. [acoustic wave reflection and transmission

    Kleinstein, G. G.; Gunzburger, M. D.

    1976-01-01

    An integral conservation law for wave numbers is considered. In order to test the validity of the proposed conservation law, a complete solution for the reflection and transmission of an acoustic wave impinging normally on a material interface moving at a constant speed is derived. The agreement between the frequency condition thus deduced from the dynamic equations of motion and the frequency condition derived from the jump condition associated with the integral equation supports the proposed law as a true conservation law. Additional comparisons such as amplitude discontinuities and Snells' law in a moving media further confirm the stated proposition. Results are stated concerning frequency and wave number relations across a shock front as predicted by the proposed conservation law.

  4. Study of the Impact of Non-linear Piezoelectric Constants on the Acoustic Wave Propagation on Lithium Niobate

    C. Soumali

    2016-06-01

    Full Text Available Impact of nonlinear piezoelectric constants on surface acoustic wave propagation on a piezoelectric substrate is investigated in this work. Propagation of acoustic wave propagation under uniform stress is analyzed; the wave equation is obtained by incorporating the applied uniform stress in the equation of motion and taking account of the set of linear and nonlinear piezoelectric constants. A new method of separation between the different modes of propagation is proposed regarding the attenuation coefficients and not to the displacement vectors. Detail calculations and simulations have made for Lithium Niobate (LiNbO3; transformations between modes of propagation, under uniform stress, have been found. These results leads to conclusion that nonlinear terms affect the acoustic wave propagation and also we can make controllable acoustic devices.

  5. TOPICAL REVIEW: Sensors and actuators based on surface acoustic waves propagating along solid liquid interfaces

    Lindner, Gerhard

    2008-06-01

    The propagation of surface acoustic waves (SAWs) along solid-liquid interfaces depends sensitively on the properties of the liquid covering the solid surface and may result in a momentum transfer into the liquid and thus a propulsion effect via acoustic streaming. This review gives an overview of the design of different SAW devices used for the sensing of liquids and the basic mechanisms of the interaction of SAWs with overlaying liquids. In addition, applications of devices based on these phenomena with respect to touch sensing and the measurement of liquid properties such as density, viscosity or the composition of mixed liquids are described, including microfabricated as well as macroscopic devices made from non-piezoelectric materials. With respect to the rapidly growing field of acoustic streaming applications, recent developments in the movement of nanolitre droplets on a single piezoelectric chip, the rather macroscopic approaches to the acoustic pumping of liquids in channels and recent attempts at numerical simulations of acoustic streaming are reported.

  6. Sensors and actuators based on surface acoustic waves propagating along solid-liquid interfaces

    The propagation of surface acoustic waves (SAWs) along solid-liquid interfaces depends sensitively on the properties of the liquid covering the solid surface and may result in a momentum transfer into the liquid and thus a propulsion effect via acoustic streaming. This review gives an overview of the design of different SAW devices used for the sensing of liquids and the basic mechanisms of the interaction of SAWs with overlaying liquids. In addition, applications of devices based on these phenomena with respect to touch sensing and the measurement of liquid properties such as density, viscosity or the composition of mixed liquids are described, including microfabricated as well as macroscopic devices made from non-piezoelectric materials. With respect to the rapidly growing field of acoustic streaming applications, recent developments in the movement of nanolitre droplets on a single piezoelectric chip, the rather macroscopic approaches to the acoustic pumping of liquids in channels and recent attempts at numerical simulations of acoustic streaming are reported. (topical review)

  7. Recent advances in lateral field excited and monolithic spiral coil acoustic transduction bulk acoustic wave sensor platforms

    The quartz crystal microbalance (QCM) has been used extensively as a bulk acoustic wave (BAW) platform for applications such as chemical and biological sensors and rate monitors in thin film deposition systems. Although the QCM is capable of measuring mechanical property changes critical in many thin film deposition systems, it cannot measure electrical property changes that can occur in many sensor applications. In this paper we review the recent developments of two novel transducer configurations for BAW sensors. In the first sensor, called the lateral field excited (LFE) sensor, the transverse shear mode (TSM) in AT-cut quartz is excited by two electrodes on the reference surface, resulting in a bare sensing surface which allows both electrical and mechanical properties of target analytes to be measured. In the second sensor, called the monolithic spiral coil acoustic transduction (MSCAT) sensor, the TSM is excited by a photolithographically deposited spiral antenna on the reference surface which can excite high-order harmonics in the substrate, and potentially lead to increased sensitivity. The responses of both the LFE and MSCAT sensors to electrical and mechanical property changes of liquids have been examined and compared to the response of the standard QCM. In addition, results relating to the detection of chemical and biological target analytes using the LFE and MSCAT sensor platforms are presented

  8. Observations of acoustic-gravity waves in the ionosphere generated by severe tropospheric weather

    Šindelářová, Tereza; Burešová, Dalia; Chum, Jaroslav

    2009-01-01

    Roč. 53, č. 3 (2009), s. 403-418. ISSN 0039-3169 R&D Projects: GA ČR GA205/07/1367; GA ČR GA205/08/1356 Institutional research plan: CEZ:AV0Z30420517 Keywords : acoustic- gravity waves * ionosphere * convective storms Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.000, year: 2009

  9. Modeling of the interaction of an acoustic wave with immersed targets for telemetry of complex structures

    Lu, Bo; Darmon, Michel; Potel, Catherine; FRADKIN, Larissa; CHATILLON, Sylvain

    2012-01-01

    This study is part of the development of simulation tools for ultrasonic telemetry. Telemetry is a technique chosen for monitoring sodium-cooled fast reactors, which consists in locating various reactor structures using an ultrasonic inspection performed by immersion. In order to model the interaction between the acoustic wave and the immersed structures, classical diffraction models have been firstly evaluated for rigid structures, including the geometrical theory of diffraction (GTD) and th...

  10. Application of ion-beam-sputtered Al films to ultrathin surface acoustic wave devices

    Ion-beam sputtering technique has been applied to Al film deposition for electrodes in high-frequency surface acoustic wave devices. Al films having low resistivity and a smooth surface have been obtained, even in the ultrathin thickness range. It was shown that the ion-beam sputtering technique provided excellent thickness uniformity and controllability. This method was also applied to the deposition of highly preferred [111]-textured Al films. (author)

  11. Solid waves and acoustic emission first phase: Problems direct and inverse and equations elasto dynamics fields

    The present work is the first of a series of three memoirs briefs, destinadas to revise the classic theoretical foundations that allow to understand the generation,la diffusion and the detection of the elastic waves in those been accustomed to from the point of view of the mechanics of the means continuos. The study is faced in the mark of the non destructive rehearsals, emphasizing aspects related with the rehearsals based on the acoustic emission of the material defects

  12. Eigenvalue solution to the electron-collisional effect on ion-acoustic and entropy waves

    2001-01-01

    The linearized electron Fokker-Planck and cold-ion fluid equations are solved as an eigenvalue problem in the quasineutral limit for ionization state,Z=1,8,and 64 for ion-acoustic and entropy waves.The perturbed electron distribution function is written as a moment expansion of eigenvectors,and is used to compute collisionality-dependence macroscopic quantities in the plasma such as the generalized specific heat ratio,and the electron thermal conductivity.

  13. Interaction of a Surface Acoustic Wave with a Two-dimensional Electron Gas

    YANG Shi-Jie; ZHAO Hu; YU Yue

    2005-01-01

    When a surface acoustic wave (SAW) propagates on the surface of a GaAs semiconductor, coupling between electrons in the two-dimensional electron gas beneath the interface and the elastic host crystal through piezoelectric interaction will attenuate the SAW. The coupling coefficient is calculated for the SAW propagating along an arbitrary direction. It is found that the coupling strength is strongly dependent on the propagating direction. When the SAW propagates along the [011] direction, the coupling becomes quite weak.

  14. Surface acoustic wave based analytical system for the detection of liquid detergents

    Vivancos, José-Luis; Racz, Zoltan; Cole, Marina; Gardner, Julian W.

    2012-01-01

    A novel analytical sensing system has been designed for the characterization and discrimination of different detergents in water. This micro-sensor system could play a key role in the development of more efficient and environmentally-friendly washing machines by enabling the measurement of residual detergents. The sensing system comprises a dual shear-horizontal surface acoustic wave (SH-SAW) resonator sensor housed within a poly-dimethylsiloxane (PDMS) microfluidic chamber. Free and electric...

  15. Experimental Study of Dust Acoustic Waves in the Strongly Correlated Regime

    Bandyopadhyay, P; Sen, A

    2016-01-01

    Low frequency dust acoustic waves (DAW) were excited in a laboratory argon dusty plasma by modulating the discharge voltage with a low frequency AC signal. Metallic graphite particles were used as dust grains and a digital FFT technique was used to obtain dispersion characteristics. The experimental dispersion relation shows the reduction of phase velocity and a regime where $\\partial \\omega/\\partial k < 0$. A comparison is made with existing theoretical model.

  16. Spherical Kadomtsev-Petviashvili equation and nebulons for dust ion-acoustic waves with symbolic computation

    Plasmas and dust exist almost everywhere in the Universe. For the dust ion-acoustic waves with zenith-angle perturbation, a spherical Kadomtsev-Petviashvili equation is derived with symbolic computation. Spherical structures of the expanding dark nebulon, shrinking dark nebulon, expanding bright nebulon and shrinking bright nebulon are symbolically obtained and discussed. Possibly-observable nebulonic effects for the future space and laboratory plasma experiments are proposed

  17. Kiwi fruit (Actinidia chinensis) quality determination based on surface acoustic wave resonator combined with electronic nose

    Wei, Liu; Guohua, Hui

    2015-01-01

    In this study, electronic nose (EN) combined with a 433 MHz surface acoustic wave resonator (SAWR) was used to determine Kiwi fruit quality under 12-day storage. EN responses to Kiwi samples were measured and analyzed by principal component analysis (PCA) and stochastic resonance (SR) methods. SAWR frequency eigen values were also measured to predict freshness. Kiwi fruit sample's weight loss index and human sensory evaluation were examined to characteristic its quality and freshness. Kiwi fr...

  18. Photonic integrated single-sideband modulator / frequency shifter based on surface acoustic waves

    Barretto, Elaine Cristina Saraiva; Hvam, Jørn Märcher

    2010-01-01

    Optical frequency shifters are essential components of many systems. In this paper, a compact integrated optical frequency shifter is designed making use of the combination of surface acoustic waves and Mach-Zehnder interferometers. It has a very simple operation setup and can be fabricated in...... standard semiconductor materials. The performance of the device is analyzed in detail, and by using multi-branch interferometers, the sensitivity of the device to fabrication tolerances can be drastically reduced....

  19. Multicomponent radiatively driven stellar winds III. Radiative-acoustic waves in a two-component wind

    Krticka, Jiri; Kubat, Jiri

    2002-01-01

    We study stability of isothermal two-component radiatively driven stellar winds against one-dimensional perturbations larger than the Sobolev length, and radiative-acoustic waves in such stellar winds. We perform linear perturbation analysis in comoving fluid-frames of individual components and obtain dispersion relation in the common fluid-frame. For high density winds the velocity difference between velocities of both components is relatively small and the wind is stable for radiative-acous...

  20. Linear and nonlinear ion-acoustic waves in non-relativistic quantum plasmas with arbitrary degeneracy

    Haas, Fernando; Mahmood, Shahzad

    2016-01-01

    Linear and nonlinear ion-acoustic waves are studied in a fluid model for non-relativistic, 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 apply equally well both to fully degenerate or classical, non-degenerate limits. Ions are assumed to be cold. Quantum diffraction effects through the Bohm potential are also taken into account. A general coupling parameter valid fo...

  1. Eigenfrequencies of Ion-Acoustic Waves in the Presence of Electron-Ion Collisions

    ZHEHG Jian; YU Chang-Xuan

    2000-01-01

    Frequencies and damping rate of ion-acoustic waves in the presence of electron-ion collisions are computed by reducing the linearized electron Fokker-Planck equation and cold-ion fluid equations to an eigenvalue equation via moment expansion of the perturbation of electron distribution function. As electrons becomes less collisional, a great number of Sonine modes are needed for convergence to a desired accuracy in the calculation, which may be ascribed to the neglected electron-electron collisions.

  2. A Novel Cell-Based Hybrid Acoustic Wave Biosensor with Impedimetric Sensing Capabilities

    Ioana Voiculescu; Anis Nurashikin Nordin; Fang Li; Fei Liu

    2013-01-01

    A novel multiparametric biosensor system based on living cells will be presented. The biosensor system includes two biosensing techniques on a single device: resonant frequency measurements and electric cell-substrate impedance sensing (ECIS). The multiparametric sensor system is based on the innovative use of the upper electrode of a quartz crystal microbalance (QCM) resonator as working electrode for the ECIS technique. The QCM acoustic wave sensor consists of a thin AT-cut quartz substrate...

  3. Quantitative Determination of Size and Shape of Surface-Bound DNA Using an Acoustic Wave Sensor

    Tsortos, Achilleas; Papadakis, George; Mitsakakis, Konstantinos; Kathryn A. Melzak; Gizeli, Electra

    2008-01-01

    DNA bending plays a significant role in many biological processes, such as gene regulation, DNA replication, and chromosomal packing. Understanding how such processes take place and how they can, in turn, be regulated by artificial agents for individual oriented therapies is of importance to both biology and medicine. In this work, we describe the application of an acoustic wave device for characterizing the conformation of DNA molecules tethered to the device surface via a biotin-neutravidin...

  4. Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

    Mitri, F. G.

    2015-12-01

    The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

  5. Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

    Lipkens, Bart, E-mail: blipkens@wne.edu [Mechanical Engineering, Western New England University, Springfield, Massachusetts, 01119 (United States); Ilinskii, Yurii A., E-mail: ilinskii@gmail.com; Zabolotskaya, Evgenia A., E-mail: zheniazabolotskaya@gmail.com [Applied Research Laboratories, The University of Texas at Austin, Austin, Texas 78713–8029 (United States)

    2015-10-28

    Ultrasonic standing waves are widely used for separation applications. In MEMS applications, a half wavelength standing wave field is generated perpendicular to a laminar flow. The acoustic radiation force exerted on the particle drives the particle to the center of the MEMS channel, where concentrated particles are harvested. In macro-scale applications, the ultrasonic standing wave spans multiple wavelengths. Examples of such applications are oil/water emulsion splitting [1], and blood/lipid separation [2]. In macro-scale applications, particles are typically trapped in the standing wave, resulting in clumping or coalescence of particles/droplets. Subsequent gravitational settling results in separation of the secondary phase. An often used expression for the radiation force on a particle is that derived by Gorkov [3]. The assumptions are that the particle size is small relative to the wavelength, and therefore, only monopole and dipole scattering contributions are used to calculate the radiation force. This framework seems satisfactory for MEMS scale applications where each particle is treated separately by the standing wave, and concentrations are typically low. In macro-scale applications, particle concentration is high, and particle clumping or droplet coalescence results in particle sizes not necessarily small relative to the wavelength. Ilinskii et al. developed a framework for calculation of the acoustic radiation force valid for any size particle [4]. However, this model does not take into account particle to particle effects, which can become important as particle concentration increases. It is known that an acoustic radiation force on a particle or a droplet is determined by the local field. An acoustic radiation force expression is developed that includes the effect of particle to particle interaction. The case of two neighboring particles is considered. The approach is based on sound scattering by the particles. The acoustic field at the location of

  6. Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

    Lipkens, Bart; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.

    2015-10-01

    Ultrasonic standing waves are widely used for separation applications. In MEMS applications, a half wavelength standing wave field is generated perpendicular to a laminar flow. The acoustic radiation force exerted on the particle drives the particle to the center of the MEMS channel, where concentrated particles are harvested. In macro-scale applications, the ultrasonic standing wave spans multiple wavelengths. Examples of such applications are oil/water emulsion splitting [1], and blood/lipid separation [2]. In macro-scale applications, particles are typically trapped in the standing wave, resulting in clumping or coalescence of particles/droplets. Subsequent gravitational settling results in separation of the secondary phase. An often used expression for the radiation force on a particle is that derived by Gorkov [3]. The assumptions are that the particle size is small relative to the wavelength, and therefore, only monopole and dipole scattering contributions are used to calculate the radiation force. This framework seems satisfactory for MEMS scale applications where each particle is treated separately by the standing wave, and concentrations are typically low. In macro-scale applications, particle concentration is high, and particle clumping or droplet coalescence results in particle sizes not necessarily small relative to the wavelength. Ilinskii et al. developed a framework for calculation of the acoustic radiation force valid for any size particle [4]. However, this model does not take into account particle to particle effects, which can become important as particle concentration increases. It is known that an acoustic radiation force on a particle or a droplet is determined by the local field. An acoustic radiation force expression is developed that includes the effect of particle to particle interaction. The case of two neighboring particles is considered. The approach is based on sound scattering by the particles. The acoustic field at the location of

  7. Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

    Ultrasonic standing waves are widely used for separation applications. In MEMS applications, a half wavelength standing wave field is generated perpendicular to a laminar flow. The acoustic radiation force exerted on the particle drives the particle to the center of the MEMS channel, where concentrated particles are harvested. In macro-scale applications, the ultrasonic standing wave spans multiple wavelengths. Examples of such applications are oil/water emulsion splitting [1], and blood/lipid separation [2]. In macro-scale applications, particles are typically trapped in the standing wave, resulting in clumping or coalescence of particles/droplets. Subsequent gravitational settling results in separation of the secondary phase. An often used expression for the radiation force on a particle is that derived by Gorkov [3]. The assumptions are that the particle size is small relative to the wavelength, and therefore, only monopole and dipole scattering contributions are used to calculate the radiation force. This framework seems satisfactory for MEMS scale applications where each particle is treated separately by the standing wave, and concentrations are typically low. In macro-scale applications, particle concentration is high, and particle clumping or droplet coalescence results in particle sizes not necessarily small relative to the wavelength. Ilinskii et al. developed a framework for calculation of the acoustic radiation force valid for any size particle [4]. However, this model does not take into account particle to particle effects, which can become important as particle concentration increases. It is known that an acoustic radiation force on a particle or a droplet is determined by the local field. An acoustic radiation force expression is developed that includes the effect of particle to particle interaction. The case of two neighboring particles is considered. The approach is based on sound scattering by the particles. The acoustic field at the location of

  8. Highly asymmetric interaction forces induced by acoustic waves in coupled plate structures

    Fan, Xiying; Zhang, Shenwei; Ke, Manzhu; Liu, Zhengyou

    2015-01-01

    Mutual forces can be induced between coupled structures when illuminated by external acoustic waves. In this Letter, we propose a concept of asymmetric interaction between two coupled plate-like structures, which is generated by oppositely incident plane waves. Besides the striking contrast in magnitude, the mutual force induced by one of the incidences can be tuned extremely strong due to the resonant excitation of the flexural plate modes. The highly asymmetric interaction with enhanced strength in single side should be potentially useful, such as in designing ultrasound instruments and sensors.

  9. Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

    Bandyopadhyay, P; Sen, A; Kaw, P K

    2016-01-01

    The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and $MnO_2$ dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of $\\partial\\omega/\\partial k < 0$ are identified as signatures of dust-dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects.

  10. Models and general wave properties of two-dimensional acoustic metamaterials and media

    Bobrovnitskii, Yu. I.

    2015-05-01

    For two-dimensional linear acoustic metamaterials and media represented in the form of periodic structures made of complex cells, a general model is proposed, formulas are derived for the effective parameters and energy characteristics, and the restrictions imposed on such media are formulated. They are divided into four main types, differing in general wave properties; the differentiating features of each type are shown. Several new schemes of negative and hyperbolic types of discrete and continuous metamaterials are presented, for which the dispersion dependences are constructed and the corresponding "wave" equations are written.

  11. Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

    Bandyopadhyay, P. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)], E-mail: pintu@ipr.res.in; Prasad, G.; Sen, A.; Kaw, P.K. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

    2007-09-03

    The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO{sub 2} dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of {partial_derivative}{omega}/{partial_derivative}k<0 are identified as signatures of dust-dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects.

  12. Experimental observation of strong coupling effects on the dispersion of dust acoustic waves in a plasma

    The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO2 dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of ∂ω/∂k<0 are identified as signatures of dust-dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects

  13. Calculation of an axial temperature distribution using the reflection coefficient of an acoustic wave.

    Červenka, Milan; Bednařík, Michal

    2015-10-01

    This work verifies the idea that in principle it is possible to reconstruct axial temperature distribution of fluid employing reflection or transmission of acoustic waves. It is assumed that the fluid is dissipationless and its density and speed of sound vary along the wave propagation direction because of the fluid temperature distribution. A numerical algorithm is proposed allowing for calculation of the temperature distribution on the basis of known frequency characteristics of reflection coefficient modulus. Functionality of the algorithm is illustrated on a few examples, its properties are discussed. PMID:26520344

  14. Temperature Frequency Characteristics of Hexamethyldisiloxane (HMDSO) Polymer Coated Rayleigh Surface Acoustic Wave (SAW) Resonators for Gas-Phase Sensor Applications

    Radeva, Ekaterina I.; Esmeryan, Karekin D.; Ivan D. Avramov

    2012-01-01

    Temperature induced frequency shifts may compromise the sensor response of polymer coated acoustic wave gas-phase sensors operating in environments of variable temperature. To correct the sensor data with the temperature response of the sensor the latter must be known. This study presents and discusses temperature frequency characteristics (TFCs) of solid hexamethyldisiloxane (HMDSO) polymer coated sensor resonators using the Rayleigh surface acoustic wave (RSAW) mode on ST-cut quartz. Using ...

  15. Three-dimensional continuous particle focusing in a microfluidic channel via standing surface acoustic waves (SSAW)†

    Shi, Jinjie; Yazdi, Shahrzad; Lin, Sz-Chin Steven; Ding, Xiaoyun; Chiang, I-Kao; Sharp, Kendra; Huang, Tony Jun

    2011-01-01

    Three-dimensional (3D) continuous microparticle focusing has been achieved in a single-layer polydimethylsiloxane (PDMS) microfluidic channel using a standing surface acoustic wave (SSAW). The SSAW was generated by the interference of two identical surface acoustic waves (SAWs) created by two parallel interdigital transducers (IDTs) on a piezoelectric substrate with a microchannel precisely bonded between them. To understand the working principle of the SSAW-based 3D focusing and investigate ...

  16. Detection of Volatile Organics Using a Surface Acoustic Wave Array System

    ANDERSON, LAWRENCE F.; BARTHOLOMEW, JOHN W.; CERNOSEK, RICHARD W.; COLBURN, CHRISTOPHER W.; CROOKS, R.M.; MARTINEZ, R.F.; OSBOURN, GORDON C.; RICCO, A.J.; STATON, ALAN W.; YELTON, WILLIAM G.

    1999-10-14

    A chemical sensing system based on arrays of surface acoustic wave (SAW) delay lines has been developed for identification and quantification of volatile organic compounds (VOCs). The individual SAW chemical sensors consist of interdigital transducers patterned on the surface of an ST-cut quartz substrate to launch and detect the acoustic waves and a thin film coating in the SAW propagation path to perturb the acoustic wave velocity and attenuation during analyte sorption. A diverse set of material coatings gives the sensor arrays a degree of chemical sensitivity and selectivity. Materials examined for sensor application include the alkanethiol-based self-assembled monolayer, plasma-processed films, custom-synthesized conventional polymers, dendrimeric polymers, molecular recognition materials, electroplated metal thin films, and porous metal oxides. All of these materials target a specific chemical fi.mctionality and the enhancement of accessible film surface area. Since no one coating provides absolute analyte specificity, the array responses are further analyzed using a visual-empirical region-of-influence (VERI) pattern recognition algorithm. The chemical sensing system consists of a seven-element SAW array with accompanying drive and control electronics, sensor signal acquisition electronics, environmental vapor sampling hardware, and a notebook computer. Based on data gathered for individual sensor responses, greater than 93%-accurate identification can be achieved for any single analyte from a group of 17 VOCs and water.

  17. Very low frequency subionospheric remote sensing of thunderstorm-driven acoustic waves in the lower ionosphere

    Marshall, R. A.; Snively, J. B.

    2014-05-01

    We present observations of narrowband subionospheric VLF transmitter signals on 20 March 2001, exhibiting coherent fluctuations of over 1 dB peak to peak. Spectral analysis shows that the fluctuations have periods of 1-4min and are largely coherent. The subionospheric propagation path of the signal from Puerto Rico to Colorado passes over two regions of convective and lightning activity, as observed by GOES satellite imagery and National Lightning Detection Network lightning data. We suggest that these fluctuations are evidence of acoustic waves launched by the convective activity below, observed in the 80-90 km altitude range to which nighttime VLF subionospheric remote sensing is sensitive. These observations show that VLF subionospheric remote sensing may provide a unique, 24h remote sensing technique for acoustic and gravity wave activity. We reproduce this event in simulations using a fluid model of gravity and acoustic wave propagation to calculate the ionospheric disturbance, followed by an electromagnetic propagation model to calculate the perturbation amplitude at the location of the VLF receiver. Simulation results show that a very large and coherent convective source is required to produce these amplitude perturbations.

  18. Argon–oxygen dc magnetron discharge plasma probed with ion acoustic waves

    The precise determination of the relative concentration of negative ions is very important for the optimization of magnetron sputtering processes, especially for those undertaken in a multicomponent background produced by adding electronegative gases, such as oxygen, to the discharge. The temporal behavior of an ion acoustic wave excited from a stainless steel grid inside the plasma chamber is used to determine the relative negative ion concentration in the magnetron discharge plasma. The phase velocity of the ion acoustic wave in the presence of negative ions is found to be faster than in a pure argon plasma, and the phase velocity increases with the oxygen partial pressure. Optical emission spectroscopy further confirms the increase in the oxygen negative ion density, along with a decrease in the argon positive ion density under the same discharge conditions. The relative negative ion concentration values measured by ion acoustic waves are compared with those measured by a single Langmuir probe, and a similarity in the results obtained by both techniques is observed

  19. Reflection of acoustic wave from the elastic seabed with an overlying gassy poroelastic layer

    Chen, Weiyun; Wang, Zhihua; Zhao, Kai; Chen, Guoxing; Li, Xiaojun

    2015-10-01

    Based on the multiphase poroelasticity theory, the reflection characteristics of an obliquely incident acoustic wave upon a plane interface between overlying water and a gassy marine sediment layer with underlying elastic solid seabed are investigated. The sandwiched gassy layer is modelled as a porous material with finite thickness, which is saturated by two compressible and viscous fluids (liquid and gas). The closed-form expression for the amplitude ratio of the reflected wave, called reflection coefficient, is derived theoretically according to the boundary conditions at the upper and lower interfaces in our proposed model. Using numerical calculation, the influences of layer thickness, incident angle, wave frequency and liquid saturation of sandwiched porous layer on the reflection coefficient are analysed, respectively. It is revealed that the reflection coefficient is closely associated with incident angle and sandwiched layer thickness. Moreover, in different frequency ranges, the dependence of the wave reflection characteristics on moisture (or gas) variations in the intermediate marine sediment layer is distinguishing.

  20. Waves and Structures in Nonlinear Nondispersive Media General Theory and Applications to Nonlinear Acoustics

    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...