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Sample records for acoustic waves trapped

  1. 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

  2. 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.

  3. 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.

  4. 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...

  5. Stimulated trapped electron-acoustic wave scattering and ion-vortices in subcritical plasmas

    Stimulated trapped electron-acoustic wave scattering instability by a linearly-polarized laser interacting with a plasma layer at a subcritical density range is studied by particle simulation. Its early behavior is almost the same whether ion dynamics is taken into account or not. However,when ion dynamics is considered, a large ion acoustic wave is excited, which grows with time and eventually breaks up locally, followed by the generation of a large amplitude electromagnetic soliton. As a new phenomenon, an ion-vortex structure in ion phase-space is formed due to the ion acceleration and trapping by high local electromagnetic and electrostatic fields inside the soliton. As the electromagnetic soliton is accelerated backwards, several ion-vortices are formed in the wake behind. Ion-vortices are also found in inhomogeneous subcritical plasmas. These ion-vortices are recognized as the Kelvin-Helmholtz instability patterns, likely to be formed due to a topological defect, i.e., the plasma density cavity in the electromagnetic soliton region, which exhibit the well-known paradigmatic Ying-Yang pattern. (authors)

  6. Nonlinear propagation of dust-acoustic solitary waves in a dusty plasma with arbitrarily charged dust and trapped electrons

    O Rahman; A A Mamun

    2013-06-01

    A theoretical investigation of dust-acoustic solitary waves in three-component unmagnetized dusty plasma consisting of trapped electrons, Maxwellian ions, and arbitrarily charged cold mobile dust was done. It has been found that, owing to the departure from the Maxwellian electron distribution to a vortex-like one, the dynamics of small but finite amplitude dust-acoustic (DA) waves is governed by a nonlinear equation of modified Korteweg–de Vries (mKdV) type (instead of KdV). The reductive perturbation method was employed to study the basic features (amplitude, width, speed, etc.) of DA solitary waves which are significantly modified by the presence of trapped electrons. The implications of our results in space and laboratory plasmas are briefly discussed.

  7. Energy trapping of thickness-extensional modes in thin film bulk acoustic wave filters

    Zinan Zhao

    2016-01-01

    Full Text Available This paper presents the thickness-extensional vibration of a rectangular piezoelectric thin film bulk acoustic wave filter with two pairs of electrodes symmetrically deposited on the center of the zinc oxide film. The two-dimensional scalar differential equations which were first derived to describe in-plane vibration distribution by Tiersten and Stevens are employed. The Ritz method with trigonometric functions as basis functions is used based on a variational formulation developed in our previous paper. Free vibration resonant frequencies and corresponding modes are obtained. The modes may separate into symmetric and antisymmetric ones for such a structurally symmetric filter. Trapped modes with vibrations mainly under the driving electrodes are exhibited. The six corner-type regions of the filter neglected by Tiersten and Stevens for an approximation are taken into account in our analysis. Results show that their approximation can lead to an inaccuracy on the order of dozens of ppm for the fundamental mode, which is quite significant in filter operation and application.

  8. Energy trapping of thickness-extensional modes in thin film bulk acoustic wave filters

    Zhao, Zinan; Qian, Zhenghua; Wang, Bin

    2016-01-01

    This paper presents the thickness-extensional vibration of a rectangular piezoelectric thin film bulk acoustic wave filter with two pairs of electrodes symmetrically deposited on the center of the zinc oxide film. The two-dimensional scalar differential equations which were first derived to describe in-plane vibration distribution by Tiersten and Stevens are employed. The Ritz method with trigonometric functions as basis functions is used based on a variational formulation developed in our previous paper. Free vibration resonant frequencies and corresponding modes are obtained. The modes may separate into symmetric and antisymmetric ones for such a structurally symmetric filter. Trapped modes with vibrations mainly under the driving electrodes are exhibited. The six corner-type regions of the filter neglected by Tiersten and Stevens for an approximation are taken into account in our analysis. Results show that their approximation can lead to an inaccuracy on the order of dozens of ppm for the fundamental mode, which is quite significant in filter operation and application.

  9. Acoustic trapping of active matter.

    Takatori, Sho C; De Dier, Raf; Vermant, Jan; Brady, John F

    2016-01-01

    Confinement of living microorganisms and self-propelled particles by an external trap provides a means of analysing the motion and behaviour of active systems. Developing a tweezer with a trapping radius large compared with the swimmers' size and run length has been an experimental challenge, as standard optical traps are too weak. Here we report the novel use of an acoustic tweezer to confine self-propelled particles in two dimensions over distances large compared with the swimmers' run length. We develop a near-harmonic trap to demonstrate the crossover from weak confinement, where the probability density is Boltzmann-like, to strong confinement, where the density is peaked along the perimeter. At high concentrations the swimmers crystallize into a close-packed structure, which subsequently 'explodes' as a travelling wave when the tweezer is turned off. The swimmers' confined motion provides a measurement of the swim pressure, a unique mechanical pressure exerted by self-propelled bodies. PMID:26961816

  10. The effect of trapped electrons on the three-dimensional ion-acoustic shock wave in magnetized ionic-pair plasma

    Guo, Shimin; Mei, Liquan; He, Ya-Ling; Guo, Huaqi; Zhao, Yanjun

    2016-04-01

    The effect of trapped electrons featuring vortex-like distribution on the nonlinear behavior of a three-dimensional ion-acoustic shock wave is investigated in a magnetized ionic-pair plasma. In the long-wave approximation, the dynamics of the shock wave is governed by the (3{+}1) -dimensional Schamel-Zakharov-Kuznetsov-Burgers' equation due to the presence of trapped electrons and ion kinematic viscosity. By using the homogeneous balance principle and tanh function method, we obtain a novel exact shock wave solution of the equation. It is found for the first time that the trapped electrons can support a shock wave with only positive polarity.

  11. Dissipative dust-acoustic shock waves in a varying charge electronegative magnetized dusty plasma with trapped electrons

    Bacha, Mustapha; Tribeche, Mouloud

    2016-08-01

    The combined effects of an oblique magnetic field and electron trapping on dissipative dust-acoustic waves are examined in varying charge electronegative dusty plasmas with application to the Halley Comet plasma (˜104 km from the nucleus). A weakly nonlinear analysis is carried out to derive a modified Korteweg-de Vries-Burger-like equation. Making use of the equilibrium current balance equation, the physically admissible values of the electron trapping parameter are first constrained. We then show that the Burger dissipative term is solely due to the dust charge variation process. It is found that an increase of the magnetic field obliqueness or a decrease of its magnitude renders the shock structure more dispersive.

  12. Self-Trapping of Acoustic Polaron in One Dimension

    HOU Jun-Hua; LIANG Xi-Xia

    2007-01-01

    The ground-state energy and effective mass of an acoustic polaron in one dimension are calculated by using an electron-longitudinal-acoustic-phonon interaction Hamiltonian derived here. The self-trapping of the acoustic polaron is discussed. It is found that the critical coupling constant shifts toward weaker electron-phonon interaction with the increasing cutoff wave vector and the products of the critical coupling constant by the cutoff wave vector tend to a certain value. The self-trapping of acoustic polarons in one dimension is easier to be realized than that in three- and two-dimensional systems. The self-trapping transition of acoustic polarons is expected to be observed in the one dimensional systems of alkali halides and wide-band-gap semiconductors.

  13. 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...

  14. 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.

  15. Acoustic rainbow trapping by coiling up space.

    Ni, Xu; Wu, Ying; Chen, Ze-Guo; Zheng, Li-Yang; Xu, Ye-Long; Nayar, Priyanka; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yan-Feng

    2014-01-01

    We numerically realize the acoustic rainbow trapping effect by tapping an air waveguide with space-coiling metamaterials. Due to the high refractive-index of the space-coiling metamaterials, our device is more compact compared to the reported trapped-rainbow devices. A numerical model utilizing effective parameters is also calculated, whose results are consistent well with the direct numerical simulation of space-coiling structure. Moreover, such device with the capability of dropping different frequency components of a broadband incident temporal acoustic signal into different channels can function as an acoustic wavelength division de-multiplexer. These results may have potential applications in acoustic device design such as an acoustic filter and an artificial cochlea. PMID:25392033

  16. Acoustic rainbow trapping by coiling up space

    Ni, Xu

    2014-11-13

    We numerically realize the acoustic rainbow trapping effect by tapping an air waveguide with space-coiling metamaterials. Due to the high refractive-index of the space-coiling metamaterials, our device is more compact compared to the reported trapped-rainbow devices. A numerical model utilizing effective parameters is also calculated, whose results are consistent well with the direct numerical simulation of space-coiling structure. Moreover, such device with the capability of dropping different frequency components of a broadband incident temporal acoustic signal into different channels can function as an acoustic wavelength division de-multiplexer. These results may have potential applications in acoustic device design such as an acoustic filter and an artificial cochlea.

  17. 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...

  18. Acoustic rainbow trapping by coiling up space

    Xu Ni; Ying Wu; Ze-Guo Chen; Li-Yang Zheng; Ye-Long Xu; Priyanka Nayar; Xiao-Ping Liu; Ming-Hui Lu; Yan-Feng Chen

    2014-01-01

    We numerically realize the acoustic rainbow trapping effect by tapping an air waveguide with space-coiling metamaterials. Due to the high refractive-index of the space-coiling metamaterials, our device is more compact compared to the reported trapped-rainbow devices. A numerical model utilizing effective parameters is also calculated, whose results are consistent well with the direct numerical simulation of space-coiling structure. Moreover, such device with the capability of dropping differe...

  19. Temperature and trapping characterization of an acoustic trap with miniaturized integrated transducers--towards in-trap temperature regulation.

    Johansson, Linda; Evander, Mikael; Lilliehorn, Tobias; Almqvist, Monica; Nilsson, Johan; Laurell, Thomas; Johansson, Stefan

    2013-07-01

    An acoustic trap with miniaturized integrated transducers (MITs) for applications in non-contact trapping of cells or particles in a microfluidic channel was characterized by measuring the temperature increase and trapping strength. The fluid temperature was measured by the fluorescent response of Rhodamine B in the microchannel. The trapping strength was measured by the area of a trapped particle cluster counter-balanced by the hydrodynamic force. One of the main objectives was to obtain quantitative values of the temperature in the fluidic channel to ensure safe handling of cells and proteins. Another objective was to evaluate the trapping-to-temperature efficiency for the trap as a function of drive frequency. Thirdly, trapping-to-temperature efficiency data enables identifying frequencies and voltage values to use for in-trap temperature regulation. It is envisioned that operation with only in-trap temperature regulation enables the realization of small, simple and fast temperature-controlled trap systems. The significance of potential gradients at the trap edges due to the finite size of the miniaturized transducers for the operation was emphasized and expressed analytically. The influence of the acoustic near field was evaluated in FEM-simulation and compared with a more ideal 1D standing wave. The working principle of the trap was examined by comparing measurements of impedance, temperature increase and trapping strength with impedance transfer calculations of fluid-reflector resonances and frequencies of high reflectance at the fluid-reflector boundary. The temperature increase was found to be moderate, 7°C for a high trapping strength, at a fluid flow of 0.5mms(-1) for the optimal driving frequency. A fast temperature response with a fall time of 8s and a rise time of 11s was observed. The results emphasize the importance of selecting the proper drive frequency for long term handling of cells, as opposed to the more pragmatic way of selecting the

  20. A high-overtone bulk acoustic wave resonator-oscillator-based 4.596 GHz frequency source: Application to a coherent population trapping Cs vapor cell atomic clock

    This article reports on the design and characterization of a high-overtone bulk acoustic wave resonator (HBAR)-oscillator-based 4.596 GHz frequency source. A 2.298 GHz signal, generated by an oscillator constructed around a thermally controlled two-port aluminum nitride-sapphire HBAR resonator with a Q-factor of 24 000 at 68 °C, is frequency multiplied by 2–4.596 GHz, half of the Cs atom clock frequency. The temperature coefficient of frequency of the HBAR is measured to be −23 ppm/ °C at 2.298 GHz. The measured phase noise of the 4.596 GHz source is −105 dB rad2/Hz at 1 kHz offset and −150 dB rad2/Hz at 100 kHz offset. The 4.596 GHz output signal is used as a local oscillator in a laboratory-prototype Cs microcell-based coherent population trapping atomic clock. The signal is stabilized onto the atomic transition frequency by tuning finely a voltage-controlled phase shifter implemented in the 2.298 GHz HBAR-oscillator loop, preventing the need for a high-power-consuming direct digital synthesis. The short-term fractional frequency stability of the free-running oscillator is 1.8 × 10−9 at one second integration time. In locked regime, the latter is improved in a preliminary proof-of-concept experiment at the level of 6.6 × 10−11 τ−1/2 up to a few seconds and found to be limited by the signal-to-noise ratio of the detected CPT resonance

  1. Acoustically trapped colloidal crystals that are reconfigurable in real time.

    Caleap, Mihai; Drinkwater, Bruce W

    2014-04-29

    Photonic and phononic crystals are metamaterials with repeating unit cells that result in internal resonances leading to a range of wave guiding and filtering properties and are opening up new applications such as hyperlenses and superabsorbers. Here we show the first, to our knowledge, 3D colloidal phononic crystal that is reconfigurable in real time and demonstrate its ability to rapidly alter its frequency filtering characteristics. Our reconfigurable material is assembled from microspheres in aqueous solution, trapped with acoustic radiation forces. The acoustic radiation force is governed by an energy landscape, determined by an applied high-amplitude acoustic standing wave field, in which particles move swiftly to energy minima. This creates a colloidal crystal of several milliliters in volume with spheres arranged in an orthorhombic lattice in which the acoustic wavelength is used to control the lattice spacing. Transmission acoustic spectroscopy shows that the new colloidal crystal behaves as a phononic metamaterial and exhibits clear band-pass and band-stop frequencies which are adjusted in real time. PMID:24706925

  2. 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.

  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. 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.

  5. 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.

  6. 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

  7. 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)

  8. Wave-trapping in an inhomogeneous magnetoplasma

    The multi-dimensional wave equations for the waves propagating along a magnetic field in an inhomogeneous plasma are derived and the wave-trapping is discussed. It is shown that the wave equations are reduced to the Schroedinger-type ones in which the sign of the coefficient of the second derivative depends on (psi/theta)sub(theta=0) where psi is the angle between the field line and the ray, and theta is the angle between the field line and the wave normal. The physical reason of the wave trapping is explained by comparing the sign of (psi/theta)sub(theta=0) with that of the effective potential in the wave equation. As an example, the wave trapping of the whistler wave in geo-magnetosphere is considered. (auth.)

  9. 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.

  10. 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....

  11. Whistler wave trapping in a density crest

    The linear trapping process of whistler waves in a field-aligned density crest is investigated theoretically and experimentally below ω = ωsub(c)/2 (half gyrofrequency). The conditions of the crest trapping are derived in terms of the frequency ω/ωsub(c), the incident wave-normal angle theta sub(i), and the density ratio n sub(i)/n sub(o), where n sub(i) and n sub(o) denote the density at the incident point and that at the ridge, respectively. The oscillation length of the trapped ray path is calculated for a parabolic density profile. The experiment on antenna-excited whistler wave has been performed in a large magnetized plasma with the density crest. The phase and amplitude profile of the whistler wave is measured along and across the crest. The measurement has verified characteristic behaviors of the crest trapping. (author)

  12. Adiabatic electron response and solitary wave generation by trapped particle nonlinearity in a hydrogen plasma

    Mandal, Debraj; Sharma, Devendra [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

    2014-10-15

    The finite amplitude ion acoustic waves that trap electrons modify the structure of the evolving nonlinear soliton solutions. In the numerical simulations, self-consistently generated solitary waves are studied that emerge as a result of a current driven microinstability growing the ion acoustic mode in a collisionless Vlasov plasma. The growth saturates as a result of nonlinear effects governed by a combination of nonlinearities originating from the hydrodynamic model and kinetic particle trapping effects. The resulting solitary waves also coexist with a finite current and an electron plasma wave capable of perturbing the trapping potential. The results of multiscale simulation are analyzed and characterized following the kinetic prescription of undamped trapped particle mode in the form of phase space vortex solutions that are generalized form of Sagdeev's solitons and obey the solutions of a modified Korteweg-de Vries equation, accounting for a stronger nonlinearity originating from the electron trapping.

  13. 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....

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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)

  19. 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.

  20. 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)

  1. 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.

  2. Adiabatic nonlinear waves with trapped particles. III. Wave dynamics

    Dodin, I. Y.; Fisch, N. J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States)

    2012-01-15

    The evolution of adiabatic waves with autoresonant trapped particles is described within the Lagrangian model developed in Paper I, under the assumption that the action distribution of these particles is conserved, and, in particular, that their number within each wavelength is a fixed independent parameter of the problem. One-dimensional nonlinear Langmuir waves with deeply trapped electrons are addressed as a paradigmatic example. For a stationary wave, tunneling into overcritical plasma is explained from the standpoint of the action conservation theorem. For a nonstationary wave, qualitatively different regimes are realized depending on the initial parameter S, which is the ratio of the energy flux carried by trapped particles to that carried by passing particles. At S < 1/2, a wave is stable and exhibits group velocity splitting. At S > 1/2, the trapped-particle modulational instability (TPMI) develops, in contrast with the existing theories of the TPMI yet in agreement with the general sideband instability theory. Remarkably, these effects are not captured by the nonlinear Schroedinger equation, which is traditionally considered as a universal model of wave self-action but misses the trapped-particle oscillation-center inertia.

  3. Characterizing Electron Trapping Nonlinearity in Langmuir Waves

    Strozzi, D J; Rose, H A; Hinkel, D E; Langdon, A B; Banks, J W

    2012-01-01

    We assess when electron trapping nonlinearities are expected to be important in Langmuir waves. The basic criterion is that the effective lifetime, t_d, of resonant electrons in the trapping region of velocity space must exceed the period of trapped motion for deeply-trapped electrons, tau_B = (n_e/delta n)^{1/2} 2pi/omega_pe. A unitless figure of merit, the "bounce number" N_B = t_d/tau_B, encapsulates this condition and allows an effective threshold amplitude for which N_B=1 to be defined. The lifetime is found for convective loss (transverse and longitudinal) out of a spatially finite Langmuir wave. Simulations of driven waves with a finite transverse profile, using the 2D-2V Vlasov code Loki, show trapping nonlinearity increases continuously with N_B for side loss, and is significant for N_B ~ 1. The lifetime due to Coulomb collisions (both electron-electron and electron-ion) is also found, with pitch-angle scattering and parallel drag and diffusion treated in a unified way. A simple way to combine convec...

  4. 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.

  5. 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...

  6. Acoustically trapped colloidal crystals that are reconfigurable in real time

    Caleap, Mihai; Drinkwater, Bruce W

    2014-01-01

    We have been working on metamaterials that are reconfigurable in real time with a view to creating genuinely active metamaterials. Such materials will allow researchers to gain unprecedented control over a range of optical and acoustic wave phenomena. To date, although numerous examples of metamaterials exist, none is reconfigurable in three dimensions. We have developed a method for creating three-dimensional colloidal crystals that are reconfigurable in real time. Our method uses acoustic a...

  7. 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.

  8. 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.

  9. 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).

  10. 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).

  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. 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.…

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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)

  18. 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.

  19. 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.

  20. Observation of a single-beam gradient force acoustical trap for elastic particles: acoustical tweezers

    Baresch, Diego; Marchiano, Régis

    2016-01-01

    The ability to manipulate matter precisely is critical for the study and development of a large variety of systems. Optical tweezers are excellent tools to handle particles ranging in size from a few micrometers to hundreds of nanometers but become inefficient and damaging on larger objects. We demonstrate for the first reported time the trapping of elastic particles by the large gradient force of a single acoustical beam in three dimensions. We show that at equal power, acoustical forces overtake by 8 orders of magnitude that of optical ones on macroscopic objects. Acoustical tweezers can push, pull and accurately control both the position of the particle and the forces exerted under damage-free conditions. The large spectrum of frequencies covered by coherent ultrasonic sources will provide a wide variety of manipulation possibilities from macro- to microscopic length scales. We believe our observations improve the prospects for wider use of non-contact manipulation in biology, biophysics, microfluidics and...

  1. 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.

  2. Acoustics forces on a solid sphere in focused sound fields and their use for acoustical traps

    Cutanda Henriquez, Vicente; Juhl, Peter Møller; Kristensen, Søren H.;

    2009-01-01

    It is known that stationary sound fields can be used to levitate small objects in air; this phenomenon has potential applications in containerless processing of materials. Recently the use of acoustic forces have been considered for the manipulation of small samples, which offers several advantages...... in the cases of hazardous substances, processing of materials under pure conditions, handling of fragile or sticky objects, for instance. Several theoretical investigations on the use of focused Gaussian and Bessel acoustic beams have been reported in literature. In those papers, water has been assumed...... as the medium for the propagation of the acoustic waves. The objective of the work to be presented has been to study the extent to which it is possible to use focused sound fields for the manipulation of a rigid sphere in air. The possibility of developing acoustical tweezers has been the main motivation...

  3. 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

  4. 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.

  5. 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...

  6. 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....

  7. 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.,...

  8. Gene expression analysis of mouse embryonic stem cells following levitation in an ultrasound standing wave trap.

    Bazou, Despina; Kearney, Roisin; Mansergh, Fiona; Bourdon, Celine; Farrar, Jane; Wride, Michael

    2011-02-01

    In the present paper, gene expression analysis of mouse embryonic stem (ES) cells levitated in a novel ultrasound standing wave trap (USWT) (Bazou et al. 2005a) at variable acoustic pressures (0.08-0.85 MPa) and times (5-60 min) was performed. Our results showed that levitation of ES cells at the highest employed acoustic pressure for 60 min does not modify gene expression and cells maintain their pluripotency. Embryoid bodies (EBs) also expressed the early and late neural differentiation markers, which were also unaffected by the acoustic field. Our results suggest that the ultrasound trap microenvironment is minimally invasive as the biologic consequences of ES cell replication and EB differentiation proceed without significantly affecting gene expression. The technique holds great promise in safe cell manipulation techniques for a variety of applications including tissue engineering and regenerative medicine. PMID:21208732

  9. 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...

  10. 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.

  11. 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

  12. 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 ...

  13. 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...

  14. 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

  15. Cell Deformation by Single-beam Acoustic Trapping: A Promising Tool for Measurements of Cell Mechanics

    Hwang, Jae Youn; Kim, Jihun; Park, Jin Man; Lee, Changyang; Jung, Hayong; Lee, Jungwoo; Shung, K. Kirk

    2016-06-01

    We demonstrate a noncontact single-beam acoustic trapping method for the quantification of the mechanical properties of a single suspended cell with label-free. Experimentally results show that the single-beam acoustic trapping force results in morphological deformation of a trapped cell. While a cancer cell was trapped in an acoustic beam focus, the morphological changes of the immobilized cell were monitored using bright-field imaging. The cell deformability was then compared with that of a trapped polystyrene microbead as a function of the applied acoustic pressure for a better understanding of the relationship between the pressure and degree of cell deformation. Cell deformation was found to become more pronounced as higher pressure levels were applied. Furthermore, to determine if this acoustic trapping method can be exploited in quantifying the cell mechanics in a suspension and in a non-contact manner, the deformability levels of breast cancer cells with different degrees of invasiveness due to acoustic trapping were compared. It was found that highly-invasive breast cancer cells exhibited greater deformability than weakly-invasive breast cancer cells. These results clearly demonstrate that the single-beam acoustic trapping technique is a promising tool for non-contact quantitative assessments of the mechanical properties of single cells in suspensions with label-free.

  16. 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.

  17. 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...

  18. 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.

  19. 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

  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

    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.

  2. 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.

  3. 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)

  4. Bessel beams in tunable acoustic gradient index lenses and optical trap assisted nanolithography

    McLeod, Euan

    2009-12-01

    Bessel beams are laser beams whose shape gives them nondiffracting and self-healing properties. They find use in applications requiring a narrow laser beam with a high depth of field. The first part of this thesis presents the study of a new adaptive optical element capable of generating rapidly tunable Bessel beams: the tunable acoustic gradient index (TAG) lens. This device uses piezoelectrically-generated acoustic waves to modulate a fluid's density and refractive index, leading to electrically controllable lensing behavior. Both modeling and experiment are used to explain the observed multiscale Bessel beams. Because the TAG lens operates at frequencies of hundreds of kilohertz, the effective Bessel beam cone angle continuously varies at timescales on the order of microseconds or smaller-orders of magnitude faster than other existing technologies. In addition, the TAG lens may be driven with a Fourier superposition of multiple frequencies, which could enable the generation of arbitrary patterns. The second part of this thesis presents the application of Bessel beams in a new probe-based direct-write optical nanolithography method called optical trap assisted nanolithography (OTAN). When compared to alternative techniques, OTAN makes probe placement and parallelization easier. The method uses Bessel beam optical tweezers to trap dielectric microspheres in close proximity to a surface. These microspheres are then illuminated with pulses from a second laser beam, whose fluence is enhanced directly below the microsphere by focusing and near-field effects to a level great enough to modify the substrate. This technique is used to produce 100 nm features, which are less than lambda/3, and whose sizes agree well with finite-difference time-domain models of the experiment. A demonstration is given of how the technique can be parallelized by trapping multiple microspheres with multiple beams and exposing all spheres in unison with a single pulsed beam. Finally, modeling

  5. Trapping and controlling the dispersive wave within a solitonic well.

    Deng, Zhixiang; Fu, Xiquan; Liu, Jun; Zhao, Chujun; Wen, Shuangchun

    2016-05-16

    We have numerically studied the effect of mutual interactions between soliton and dispersive waves and the possibility to create a solitonic well consisting of initial twin-solitons moving away from each other to trap the incident dispersive wave. Different from the case of the solitonic cage formed by the velocity-matched twin-solitons, the intense dispersive wave can break up into small pulses, which are almost completely trapped within the solitonic well. Moreover, the corresponding spectrum of the trapped dispersive wave can be narrowed firstly and then expanded, and a new dispersive wave can be generated as the twin-solitons collision occurred. By adjusting either the peak power or temporal width of incident dispersive wave, both the intensity of the collision-induced dispersive wave and the position where it is generated can be controlled. PMID:27409855

  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. Rapid energization of radiation belt electrons by nonlinear wave trapping

    Y. Katoh

    2008-11-01

    Full Text Available We show that nonlinear wave trapping plays a significant role in both the generation of whistler-mode chorus emissions and the acceleration of radiation belt electrons to relativistic energies. We have performed particle simulations that successfully reproduce the generation of chorus emissions with rising tones. During this generation process we find that a fraction of resonant electrons are energized very efficiently by special forms of nonlinear wave trapping called relativistic turning acceleration (RTA and ultra-relativistic acceleration (URA. Particle energization by nonlinear wave trapping is a universal acceleration mechanism that can be effective in space and cosmic plasmas that contain a magnetic mirror geometry.

  8. Trapped particle effect on modulational instability of plasma wave

    A problem of stability of high amplitude plasma wave, in which field acceleration of particles takes place, is important in physics of high-energy plasma accelerators. Instabilities (modulational instability in particular) are factors restricting acceleration time and hindering realization of the main metric of charge density waves - extremely high acceleration rate. Trapped particle effect on modulational instability of plasma wave is considered

  9. 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...

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. Threshold for Electron Trapping Nonlinearity in Langmuir Waves

    Strozzi, D. J.; Williams, E. A.; Rose, H.A.; Hinkel, D. E.; Langdon, A. B.; Banks, J. W.

    2012-01-01

    We assess when electron trapping nonlinearity is expected to be important in Langmuir waves. The basic criterion is that the inverse of the detrapping rate nu_d of electrons in the trapping region of velocity space must exceed the bounce period of deeply-trapped electrons, tau_B = (n_e/delta n)^{1/2} 2pi/omega_pe. A unitless figure of merit, the "bounce number" N_B = 1/(nu_d tau_B), encapsulates this condition and defines a trapping threshold amplitude for which N_B=1. The detrapping rate is ...

  16. 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.

  17. 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.

  18. 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.

  19. Decelerating and trapping molecules in a traveling wave decelerator

    Quintero-Pérez, Marina; Wall, Thomas E; van der Berg, Joost E; Hoekstra, Steven; Bethlem, Hendrick L

    2013-01-01

    We present experiments on decelerating and trapping ammonia molecules using a combination of a Stark decelerator and a traveling wave decelerator. In the traveling wave decelerator a moving potential is created by a series of ring-shaped electrodes to which oscillating high voltages are applied. By lowering the frequency of the applied voltages, the molecules confined in the moving trap are decelerated and brought to a standstill. As the molecules are con?ned in a true 3D well, this new kind of deceleration has practically no losses, resulting in a great improvement on the usual Stark deceleration techniques. The necessary voltages are generated by amplifying the output of an arbitrary wave generator using fast HV-amplifiers, giving us great control over the trapped molecules. We illustrate this by experiments in which we adiabatically cool trapped NH3 and ND3 molecules and resonantly excite their motion.

  20. 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)

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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...

  9. 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

  10. 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.

  11. 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.

  12. 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).

  13. 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 .

  14. Nonlinear trapped electron response for drift wave turbulence in tokamaks

    The nonlinear trapped electron response to drift wave fluctuations is calculated using the coherent approximation to the DIA in action-angle variables appropriate for toroidal geometry. The bounce-averaged nonlinear response to low frequency electrostatic fluctuations is computed. Employing a spectrum of Pearlstein-Berk structure modes satisfying the symmetry of the ballooning representation, the nonlinear terms are evaluated explicitly. Nonlinear effects do not significantly modify the trapped electron response. Quasineutrality and the nonlinear ion response can then be used in a sheared slab to obtain the turbulence level at saturation level. The level of trapped electron diffusion is calculated

  15. 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...

  16. 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

  17. 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)

  18. Trapped mountain wave excitations over the Kathmandu valley, Nepal

    Regmi, Ram P.; Maharjan, Sangeeta

    2015-11-01

    Mid-wintertime spatial and temporal distributions of mountain wave excitation over the Kathmandu valley has been numerically simulated using Weather Research and Forecasting (WRF) modeling system. The study shows that low-level trapped mountain waves may remain very active during the night and early morning in the sky over the southern rim of the surrounding mountains, particularly, over the lee of Mt. Fulchoki. Calculations suggest that mountain wave activities are at minimum level during afternoon. The low-level trapped mountain waves in the sky over southern gateway of Tribhuvan International Airport (TIA) may pose risk for landings and takeoffs of light aircrafts. Detailed numerical and observational studies would be very important to reduce risk of air accidents and discomfort in and around the Kathmandu valley.

  19. 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

  20. Sub-wavelength energy trapping of elastic waves in a metamaterial.

    Colombi, Andrea; Roux, Philippe; Rupin, Matthieu

    2014-08-01

    Deep sub-wavelength focusing has been demonstrated for locally resonant metamaterials using electromagnetic and acoustic waves. The elastic equivalents of such objects are made of sub-wavelength resonating beams fixed to a two-dimensional plate, as presented here. Independent of a random or regular arrangement of the resonators, the metamaterial shows large bandgaps that are independent of the incident wave direction. Numerical simulations demonstrate that the insertion of a defect in the layout, as a shorter resonator, creates strong amplification of the wave-field on the defect. This energy trapping, which is localized on a spatial scale that is much smaller than the wavelength in the two-dimensional plate, leads to a >1 factor in terms of the local density of energy. PMID:25096146

  1. 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.

  2. 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.

  3. Effect of Existence of Red Blood Cells in Trapping Performance of Microbubbles by Acoustic Radiation Force

    Masuda, Kohji; Nakamoto, Ryusuke; Watarai, Nobuyuki; Koda, Ren; Taguchi, Yuto; Kozuka, Teruyuki; Miyamoto, Yoshitaka; Kakimoto, Takashi; Enosawa, Shin; Chiba, Toshio

    2011-07-01

    We have proposed a method to control microbubbles by making use of acoustic radiation force, which is generated with acoustic propagation, to correspond to therapeutic applications of ultrasound. By preventing bubbles from passing through the desired target area, the local concentration of bubbles can be enhanced. However, we have never experimentally confirmed this phenomenon under in vivo conditions or close to those. Thus, we carried out an experiment to evaluate the trapping performance of bubbles using a suspension of red blood cells (RBCs) and an artificial blood vessel. By defining the trapping index to evaluate the amount of trapped microbubbles, we have confirmed that the trapping performance was enhanced according to the concentration of RBCs and the sound pressure, but not according to the central frequency of ultrasound. The results indicate that the existence of RBCs near microbubbles contributed to the increase in the size of aggregations propelled against the vessel wall.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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 ...

  11. 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...

  12. 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)

  13. 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)

  14. 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

  15. 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)

  16. 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...

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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...

  5. 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

  6. 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

  7. Trapping of waves and null geodesics for rotating black holes

    Dyatlov, Semyon; Zworski, Maciej

    2013-01-01

    We present dynamical properties of linear waves and null geodesics valid for Kerr and Kerr-de Sitter black holes and their stationary perturbations. The two are intimately linked by the geometric optics approximation. For the nullgeodesic flow the key property is the r-normal hyperbolicity of the trapped set and for linear waves it is the distribution of quasi-normal modes: the exact quantization conditions do not hold for perturbations but the bounds on decay rates and the statistics of freq...

  8. 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.

  9. 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.

  10. 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.

  11. 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...

  12. 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 ...

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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...

  18. 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.

  19. 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.

  20. 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

  1. 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...

  2. 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

  3. 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.

  4. 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...

  5. Weak Nonlinear Matter Waves in a Trapped Spin-1 Condensates

    CAI Hong-Qiang; YANG Shu-Rong; XUE Ju-Kui

    2011-01-01

    The dynamics of the weak nonlinear matter solitary waves in a spin-1 condensates with harmonic external potential are investigated analytically by a perturbation method. It is shown that, in the small amplitude limit, the dynamics of the solitary waves are governed by a variable-coefficient Korteweg-de Vries (KdV) equation. The reduction to the (KdV) equation may be useful to understand the dynamics of nonlinear matter waves in spinor BEGs. The analytical expressions for the evolution of soliton show that the small-amplitude vector solitons of the mixed types perform harmonic oscillations in the presence of the trap. Furthermore, the emitted radiation profiles and the soliton oscillation freauencv are also obtained.

  6. 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.

  7. (2+1)-Dimensional Electron Acoustic Solitary Waves in an Unmagnetized Collisionless Plasma with Vortex-Like Hot Electrons

    LIN Mai-Mai; DUAN Wen-Shan

    2007-01-01

    In this paper,(2+1)-dimensional electron acoustic waves (EAW) in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique,respectively.The dispersion relation and a modified Kadomtsev-Petviashvili (KP) equation have been obtained for the EAW in the plasma considering a cold electron fluid and a vortex-like hot electrons.It is found from some numerical results that the parameter β (the ratio of the free hot electron temperature to the hot trapped electron temperature) effects on the amplitude and the width of the electron acoustic solitary waves (EASW).It can be indicated that the free hot electron temperature and the hot trapped electron temperature have very important effect on the characters of the propagation for the EASW.

  8. 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.

  9. 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)

  10. 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...

  11. 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.

  12. 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.

  13. 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.

  14. Dexterous acoustic trapping and patterning of particles assisted by phononic crystal plate

    In this letter, we present experimental demonstration of multi-particles trapping and patterning by the artificially engineered acoustic field of phononic crystal plate. Polystyrene particles are precisely trapped and patterned in two dimensional arrays, for example, the square, triangular, or quasi-periodic arrays, depending on the structures of the phononic crystal plates with varying sub-wavelength holes array. Analysis shows that the enhanced acoustic radiation force, induced by the resonant transmission field highly localized near the sub-wavelength apertures, accounts for the particles self-organizing. It can be envisaged that this kind of simple design of phononic crystal plates would pave an alternative route for self-assembly of particles and may be utilized in the lab-on-a-chip devices

  15. 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.

  16. 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.

  17. Screening of cell-drug interactions using acoustic trapping and MALDI MS

    Teppo, Jaakko

    2015-01-01

    The properties of liquid and gas flows in microscale systems differ from those in macroscale; microfluidics is a field of science in which these properties are investigated and utilized for the development of microscale systems. Acoustofluidics is a branch of microfluidics focusing on the movement (acoustophoresis) or localization (acoustic trapping) of particles in microchannels using ultrasound. In this work, the suitability of a new miniaturized method for the screening of cell-drug in...

  18. 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...

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. Matter-wave recombiners for trapped Bose-Einstein condensates

    Berrada, T.; van Frank, S.; Bücker, R.; Schumm, T.; Schaff, J.-F.; Schmiedmayer, J.; Julía-Díaz, B.; Polls, A.

    2016-06-01

    Interferometry with trapped atomic Bose-Einstein condensates (BECs) requires the development of techniques to recombine the two paths of the interferometer and map the accumulated phase difference to a measurable atom number difference. We have implemented and compared two recombining procedures in a double-well-based BEC interferometer. The first procedure utilizes the bosonic Josephson effect and controlled tunneling of atoms through the potential barrier, similar to laser light in an optical fiber coupler. The second one relies on the interference of the reflected and transmitted parts of the BEC wave function when impinging on the potential barrier, analogous to light impinging on a half-silvered mirror. Both schemes were implemented successfully, yielding an interferometric contrast of ˜20 % and 42% respectively. Building efficient matter-wave recombiners represents an important step towards the coherent manipulation of external quantum superposition states of BECs.

  5. 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...

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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.)

  12. 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.

  13. 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.

  14. 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.

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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 $\\theta$...

  20. 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)

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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...

  17. 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

  18. 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.

  19. 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.

  20. Near-field acoustic microbead trapping as remote anchor for single particle manipulation

    Hwang, Jae Youn [Department of Information and Communication Engineering, Daegu Gyeongbuk Institute of Science and Technology, Daegu (Korea, Republic of); Cheon, Dong Young; Shin, Hyunjune; Kim, Hyun Bin; Lee, Jungwoo, E-mail: jwlee@kw.ac.kr [Department of Electronic Engineering, Kwangwoon University, Seoul (Korea, Republic of)

    2015-05-04

    We recently proposed an analytical model of a two-dimensional acoustic trapping of polystyrene beads in the ray acoustics regime, where a bead diameter is larger than the wavelength used. As its experimental validation, this paper demonstrates the transverse (or lateral) trapping of individual polystyrene beads in the near field of focused ultrasound. A 100 μm bead is immobilized on the central beam axis by a focused sound beam from a 30 MHz single element lithium niobate transducer, after being laterally displaced through hundreds of micrometers. Maximum displacement, a longest lateral distance at which a trapped bead can be directed towards the central axis, is thus measured over a discrete frequency range from 24 MHz to 36 MHz. The displacement data are found to be between 323.7 μm and 470.2 μm, depending on the transducer's driving frequency and input voltage amplitude. The experimental results are compared with their corresponding model values, and their relative errors lie between 0.9% and 3.9%. The results suggest that this remote maneuvering technique may be employed to manipulate individual cells through solid microbeads, provoking certain cellular reactions to localized mechanical disturbance without direct contact.

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Multi-dimensional dynamics of stimulated Brillouin scattering in a laser speckle: Ion acoustic wave bowing, breakup, and laser-seeded two-ion-wave decay

    Albright, B. J.; Yin, L.; Bowers, K. J.; Bergen, B.

    2016-03-01

    Two- and three-dimensional particle-in-cell simulations of stimulated Brillouin scattering (SBS) in laser speckle geometry have been analyzed to evaluate the relative importance of competing nonlinear processes in the evolution and saturation of SBS. It is found that ion-trapping-induced wavefront bowing and breakup of ion acoustic waves (IAW) and the associated side-loss of trapped ions dominate electron-trapping-induced IAW wavefront bowing and breakup, as well as the two-ion-wave decay instability over a range of Z Te/Ti conditions and incident laser intensities. In the simulations, the latter instability does not govern the nonlinear saturation of SBS; however, evidence of two-ion-wave decay is seen, appearing as a modulation of the ion acoustic wavefronts. This modulation is periodic in the laser polarization plane, anti-symmetric across the speckle axis, and of a wavenumber matching that of the incident laser pulse. A simple analytic model is provided for how spatial "imprinting" from a high frequency inhomogeneity (in this case, the density modulation from the laser) in an unstable system with continuum eigenmodes can selectively amplify modes with wavenumbers that match that of the inhomogeneity.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. Quantum Entropic Dynamics of a Trapped Ion in a Standing Wave

    FANG Mao-Fa; ZHOU Peng; S. Swain

    2000-01-01

    By performing a unitary transformation, we transform the Hamiltonian of the trapped ion in any position of standing wave to that of the normal Jaynes-Cummings model in ionic bare basis and we obtain a general evolution operator of the trapped ion system. We study the quantum entropic dynamics of the phonons and trapped ion.Our results show that, when the trapped ion is located at the node of standing wave, the quantum entropic dynamics of phonons and trapped ion are the same as the one of the field in the Jaynes-Cummings model.When the trapped ion deviatesfrom the node of standing wave, the entropies of the phonons and ion keep their maximum value except at the initial stage, and the phonons and trapped ion become extremely entangled.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. 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...

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. Electrostatic Generation of Bulk Acoustic Waves and Electrical Parameters of Si-MEMS Resonators.

    Dulmet, Bernard; Ivan, Mihaela Eugenia; Ballandras, Sylvain

    2016-02-01

    This paper proposes an analytical approach to model the generation of bulk acoustic waves in an electrostatically excited silicon MEMS structure, as well as its electromechanical response in terms of static and dynamic displacements, electromechanical coupling, and motional current. The analysis pertains to the single-port electrostatic drive of trapped-energy thickness-extensional (TE) modes in thin plates. Both asymmetric single-side and symmetric double-side electrostatic gap configurations are modeled. Green's function is used to describe the characteristic of the static displacement of the driven surface of the structure versus the dc bias voltage, which allows us to determine the electrical response of the resonator. Optical and electrical characterizations have been performed on resonator samples operating at 10.3 MHz on the fundamental of TE mode under single-side electrostatic excitation. The various figures of merit depend on the dc bias voltage. Typical values of 9000 for the Q-factor, and of 10(-5) for the electromechanical coupling factor k(2) have been obtained with [Formula: see text] for [Formula: see text]-thick gaps. Here-considered modes have a typical temperature coefficients of frequency (TCF) close to -30 ppm/(°)C. We conclude that the practical usability of such electrostatically excited bulk acoustic waves (BAW) resonators essentially depends on the efficiency of the compensation of feed-through capacitance. PMID:26642450

  7. Coherent coupling between radiofrequency, optical and acoustic waves in piezo-optomechanical circuits

    Balram, Krishna C.; Davanço, Marcelo I.; Song, Jin Dong; Srinivasan, Kartik

    2016-05-01

    Optomechanical cavities have been studied for applications ranging from sensing to quantum information science. Here, we develop a platform for nanoscale cavity optomechanical circuits in which optomechanical cavities supporting co-localized 1,550 nm photons and 2.4 GHz phonons are combined with photonic and phononic waveguides. Working in GaAs facilitates manipulation of the localized mechanical mode either with a radiofrequency field through the piezo-electric effect, which produces acoustic waves that are routed and coupled to the optomechanical cavity by phononic-crystal waveguides, or optically through the strong photoelastic effect. Together with mechanical state preparation and sensitive readout, we use this to demonstrate an acoustic wave interference effect, similar to atomic coherent population trapping, in which radiofrequency-driven coherent mechanical motion is cancelled by optically driven motion. Manipulating cavity optomechanical systems with equal facility through both photonic and phononic channels enables new architectures for signal transduction between the optical, electrical and mechanical domains.

  8. Stability of relativistic electron trapping by strong whistler or electromagnetic ion cyclotron waves

    Artemyev, A. V.; Mourenas, D.; Agapitov, O. V.; Vainchtein, D. L.; Mozer, F. S.; Krasnoselskikh, V.

    2015-08-01

    In the present paper, we investigate the trapping of relativistic electrons by intense whistler-mode waves or electromagnetic ion cyclotron waves in the Earth's radiation belts. We consider the non-resonant impact of additional, lower amplitude magnetic field fluctuations on the stability of electron trapping. We show that such additional non-resonant fluctuations can break the adiabatic invariant corresponding to trapped electron oscillations in the effective wave potential. This destruction results in a diffusive escape of electrons from the trapped regime of motion and thus can lead to a significant reduction of the efficiency of electron acceleration. We demonstrate that when energetic electrons are trapped by intense parallel or very oblique whistler-mode waves, non-resonant magnetic field fluctuations in the whistler-mode frequency range with moderate amplitudes around 3 -15 pT (much less intense than the primary waves) can totally disrupt the trapped motion. However, the trapping of relativistic electrons by electromagnetic ion cyclotron waves is noticeably more stable. We also discuss how the proposed approach can be used to estimate the effects of wave amplitude modulations on the motion of trapped particles.

  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. Quantum teleportation of electrons in quantum wires with surface acoustic waves

    Buscemi, Fabrizio; Bertoni, Andrea

    2009-01-01

    We propose and numerically simulate a semiconductor device based on coupled quantum wires, suitable for deterministic quantum teleportation of electrons trapped in the minima of surface acoustic waves.We exploit a network of interacting semiconductor quantum wires able to provide the universal set of gates for quantum information processing, with the qubit defined by the localization of a single electron in one of two coupled channels.The numerical approach is based on a time-dependent solution of the three-particle Schr\\"odinger equation. First, a maximally entangled pair of electrons is obtained via Coulomb interaction between carriers in different channels. Then, a complete Bell-state measurement involving one electron from this pair and a third electron is performed. Finally, the teleported state is reconstructed by means of local one-qubit operations. The large estimated fidelity explicitely suggests that an efficient teleportation process could be reached in an experimental setup.