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Sample records for acoustic wave generated

  1. Acoustic wave generation by microwaves and applications to nondestructive evaluation.

    PubMed

    Hosten, Bernard; Bacon, Christophe; Guilliorit, Emmanuel

    2002-05-01

    Although acoustic wave generation by electromagnetic waves has been widely studied in the case of laser-generated ultrasounds, the literature on acoustic wave generation by thermal effects due to electromagnetic microwaves is very sparse. Several mechanisms have been suggested to explain the phenomenon of microwave generation, i.e. radiation pressure, electrostriction or thermal expansion. Now it is known that the main cause is the thermal expansion due to the microwave absorption. This paper will review the recent advances in the theory and experiments that introduce a new way to generate ultrasonic waves without contact for the purpose of nondestructive evaluation and control. The unidirectional theory based on Maxwell's equations, heat equation and thermoviscoelasticity predicts the generation of acoustic waves at interfaces and inside stratified materials. Acoustic waves are generated by a pulsed electromagnetic wave or a burst at a chosen frequency such that materials can be excited with a broad or narrow frequency range. Experiments show the generation of acoustic waves in water, viscoelastic polymers and composite materials shaped as rod and plates. From the computed and measured accelerations at interfaces, the viscoelastic and electromagnetic properties of materials such as polymers and composites can be evaluated (NDE). Preliminary examples of non-destructive testing applications are presented. PMID:12159977

  2. Generation of currents in the solar atmosphere by acoustic waves

    NASA Astrophysics Data System (ADS)

    Riutov, D. D.; Riutova, M. P.

    The novel mechanism presented for current and magnetic field generation by acoustic-wave fluxes in solar plasmas is especially potent in the region where acoustic-wave damping is due to such nonlinear effects as weak-shock formation. An evaluation is made of the significance of this effect for the solar atmosphere, under the proviso that this treatment is restricted to effects due to the usual acoustic waves. Wave absorption is governed by the classical collisional effects of thermal conductivity, viscosity, and ohmic losses.

  3. Interaction of acoustic waves generated by coupled plate

    NASA Technical Reports Server (NTRS)

    Cuschieri, J. M.

    1990-01-01

    When two substructures are coupled, the acoustic field generated by the motion of each of the substructures will interact with the motion of the other substructure. This would be the case of a structure enclosing an acoustic cavity. A technique to model the interaction of the generated sound fields from the two components of a coupled structure, and the influence of this interaction on the vibration of the structural components is presented. Using a mobility power flow approach, each element of the substructure is treated independently both when developing the structural response and when determining the acoustic field generated by this component. The presence of the other substructural components is introduced by assuming these components to be rigid baffles. The excitation of one of the substructures is assumed to be by an incident acoustic wave which is dependent of the motion of the substructure. The sound field generated by the motion of the substructure is included in the solution of the response.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. On acoustic wave generation in uniform shear flow

    NASA Astrophysics Data System (ADS)

    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.

  6. Anisotropic Swirling Surface Acoustic Waves from Inverse Filtering for On-Chip Generation of Acoustic Vortices

    NASA Astrophysics Data System (ADS)

    Riaud, Antoine; Thomas, Jean-Louis; Charron, Eric; Bussonnière, Adrien; Bou Matar, Olivier; Baudoin, Michael

    2015-09-01

    From radio-electronics signal analysis to biological sample actuation, surface acoustic waves (SAWs) are involved in a multitude of modern devices. However, only the most simple standing or progressive waves such as plane and focused waves have been explored so far. In this paper, we expand the SAW toolbox with a wave family named "swirling surface acoustic waves" which are the 2D anisotropic analogue of bulk acoustic vortices. 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. After the rigorous mathematical definition of these waves, we synthesize them experimentally through the inverse filtering technique revisited for surface waves. For this purpose, we design a setup combining arrays of interdigitated transducers and a multichannel electronic that enables one to synthesize any prescribed wave field compatible with the anisotropy of the substrate in a region called the "acoustic scene." This work opens prospects for the design of integrated acoustic vortex generators for on-chip selective acoustic tweezing.

  7. Effect of nonadiabaticity of dust charge variation on dust acoustic waves: generation of dust acoustic shock waves.

    PubMed

    Gupta, M R; Sarkar, S; Ghosh, S; Debnath, M; Khan, M

    2001-04-01

    The effect of nonadiabaticity of dust charge variation arising due to small nonzero values of tau(ch)/tau(d) has been studied where tau(ch) and tau(d) are the dust charging and dust hydrodynamical time scales on the nonlinear propagation of dust acoustic waves. Analytical investigation shows that the propagation of a small amplitude wave is governed by a Korteweg-de Vries (KdV) Burger equation. Notwithstanding the soliton decay, the "soliton mass" is conserved, but the dissipative term leads to the development of a noise tail. Nonadiabaticity generated dissipative effect causes the generation of a dust acoustic shock wave having oscillatory behavior on the downstream side. Numerical investigations reveal that the propagation of a large amplitude dust acoustic shock wave with dust density enhancement may occur only for Mach numbers lying between a minimum and a maximum value whose dependence on the dusty plasma parameters is presented. PMID:11308955

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    Acoustic signals generated by filamentation of ultrashort terawatt 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.

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

    PubMed

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

    2016-06-01

    Acoustic signals generated by filamentation of ultrashort terawatt 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. PMID:27415357

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

    SciTech Connect

    Armstrong, M; Reed, E; Kim, K; Glownia, J; Howard, W M; Piner, E; Roberts, J

    2008-08-14

    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.

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

    NASA Astrophysics Data System (ADS)

    Pezeril, Thomas

    2016-09-01

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

  12. Laser induced plane acoustic wave generation, propagation, and interaction with rigid structures in water

    NASA Astrophysics Data System (ADS)

    Ko, Seung H.; Ryu, Sang G.; Misra, Nipun; Pan, Heng; Grigoropoulos, Costas P.; Kladias, Nick; Panides, Elias; Domoto, Gerald A.

    2008-10-01

    Short pulsed laser induced single acoustic wave generation, propagation, interaction with rigid structures, and focusing in water are experimentally and numerically studied. A large area short duration single plane acoustic wave was generated by the thermoelastic interaction of a homogenized nanosecond pulsed laser beam with a liquid-solid interface and propagated at the speed of sound in water. Laser flash schlieren photography was used to visualize the transient interaction of the plane acoustic wave with various submerged rigid structures [(a) a single block, (b) double blocks, (c) 33° tilted single block, and (d) concave cylindrical acoustic lens configurations]. Excellent agreement between the experimental results and numerical simulation is observed. Our simulation results demonstrate that the laser induced planar acoustic wave can be focused down to several tens of micron size and several bars in pressure.

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

    NASA Astrophysics Data System (ADS)

    Shimizu, Dai; Sugimoto, Nobumasa

    2015-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  15. Influence of viscoelastic property on laser-generated surface acoustic waves in coating-substrate systems

    SciTech Connect

    Sun Hongxiang; Zhang Shuyi; Xu Baiqiang

    2011-04-01

    Taking account of the viscoelasticity of materials, the pulsed laser generation of surface acoustic waves in coating-substrate systems has been investigated quantitatively by using the finite element method. The displacement spectra of the surface acoustic waves have been calculated in frequency domain for different coating-substrate systems, in which the viscoelastic properties of the coatings and substrates are considered separately. Meanwhile, the temporal displacement waveforms have been obtained by applying inverse fast Fourier transforms. The numerical results of the normal surface displacements are presented for different configurations: a single plate, a slow coating on a fast substrate, and a fast coating on a slow substrate. The influences of the viscoelastic properties of the coating and the substrate on the attenuation of the surface acoustic waves have been studied. In addition, the influence of the coating thickness on the attenuation of the surface acoustic waves has been also investigated in detail.

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

    NASA Astrophysics Data System (ADS)

    Snively, J. B.

    2013-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Rahman, Aowabin

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

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

    SciTech Connect

    Destgeer, Ghulam; Im, Sunghyuk; Hang Ha, Byung; Ho Jung, Jin; Ahmad Ansari, Mubashshir; Jin Sung, Hyung

    2014-01-13

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

  19. Generation of infrasonic waves by low-frequency dust acoustic perturbations in the Earth's lower ionosphere

    SciTech Connect

    Kopnin, S. I.; Popel, S. I.

    2008-06-15

    It is shown that, during Perseid, Geminid, Orionid, and Leonid meteor showers, the excitation of low-frequency dust acoustic perturbations by modulational instability in the Earth's ionosphere can lead to the generation of infrasonic waves. The processes accompanying the propagation of these waves are considered, and the possibility of observing the waves from the Earth's surface is discussed, as well as the possible onset of acoustic gravitational vortex structures in the region of dust acoustic perturbations. The generation of such structures during Perseid, Geminid, Orionid, and Leonid meteor showers can show up as an increase in the intensity of green nightglow by an amount on the order of 10% and can be attributed to the formation of nonlinear (vortex) structures at altitudes of 110-120 km.

  20. Ionospheric response to infrasonic-acoustic waves generated by natural hazard events

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    Recent measurements of GPS-derived total electron content (TEC) reveal acoustic wave periods of ˜1-4 min in the F region ionosphere following natural hazard events, such as earthquakes, severe weather, and volcanoes. Here we simulate the ionospheric responses to infrasonic-acoustic waves, generated by vertical accelerations at the Earth's surface or within the lower atmosphere, using a compressible atmospheric dynamics model to perturb a multifluid ionospheric model. Response dependencies on wave source geometry and spectrum are investigated at middle, low, and equatorial latitudes. Results suggest constraints on wave amplitudes that are consistent with observations and that provide insight on the geographical variability of TEC signatures and their dependence on the geometry of wave velocity field perturbations relative to the ambient geomagnetic field. Asymmetries of responses poleward and equatorward from the wave sources indicate that electron perturbations are enhanced on the equatorward side while field aligned currents are driven principally on the poleward side, due to alignments of acoustic wave velocities parallel and perpendicular to field lines, respectively. Acoustic-wave-driven TEC perturbations are shown to have periods of ˜3-4 min, which are consistent with the fraction of the spectrum that remains following strong dissipation throughout the thermosphere. Furthermore, thermospheric acoustic waves couple with ion sound waves throughout the F region and topside ionosphere, driving plasma disturbances with similar periods and faster phase speeds. The associated magnetic perturbations of the simulated waves are calculated to be observable and may provide new observational insight in addition to that provided by GPS TEC measurements.

  1. Acoustic waves generated by a laser point source in an isotropic cylinder

    NASA Astrophysics Data System (ADS)

    Pan, Yongdong; Rossignol, Clément; Audoin, Bertrand

    2004-08-01

    The acoustic field of a homogeneous and isotropic cylinder generated by a laser point source in either ablation or thermoelastic regime is obtained theoretically. A three-dimensional Fourier transform is used to calculate the acoustic displacement at the cylinder surface. Experimental waveforms were measured and analyzed for both regimes. Theoretical normal displacements under either regime are calculated and compared to the experimental signals for aluminum cylinders. Very good agreements are observed in the arrival time, shape, and relative amplitude (i) of the cylindrical Rayleigh waves with different round trips, and (ii) of the various longitudinal and transverse bulk waves propagating through the cylinder or reflected at the free circular surface.

  2. Surface acoustic wave generation and detection using graphene interdigitated transducers on lithium niobate

    SciTech Connect

    Mayorov, A. S.; Hunter, N.; Muchenje, W.; Wood, C. D.; Rosamond, M.; Linfield, E. H.; Davies, A. G.; Cunningham, J. E.

    2014-02-24

    We demonstrate the feasibility of using graphene as a conductive electrode for the generation and detection of surface acoustic waves at 100 s of MHz on a lithium niobate substrate. The graphene interdigitated transducers (IDTs) show sensitivity to doping and temperature, and the characteristics of the IDTs are discussed in the context of a lossy transmission line model.

  3. Coherent Generation of Photo-Thermo-Acoustic Wave from Graphene Sheets

    PubMed Central

    Tian, Yichao; Tian, He; Wu, Y. L.; Zhu, L. L.; Tao, L. Q.; Zhang, W.; Shu, Y.; Xie, D.; Yang, Y.; Wei, Z. Y.; Lu, X. H.; Ren, Tian-Ling; Shih, Chih-Kang; Zhao, Jimin

    2015-01-01

    Many remarkable properties of graphene are derived from its large energy window for Dirac-like electronic states and have been explored for applications in electronics and photonics. In addition, strong electron-phonon interaction in graphene has led to efficient photo-thermo energy conversions, which has been harnessed for energy applications. By combining the wavelength independent absorption property and the efficient photo-thermo energy conversion, here we report a new type of applications in sound wave generation underlined by a photo-thermo-acoustic energy conversion mechanism. Most significantly, by utilizing ultrafast optical pulses, we demonstrate the ability to control the phase of sound waves generated by the photo-thermal-acoustic process. Our finding paves the way for new types of applications for graphene, such as remote non-contact speakers, optical-switching acoustic devices, etc. PMID:26053560

  4. Coherent Generation of Photo-Thermo-Acoustic Wave from Graphene Sheets.

    PubMed

    Tian, Yichao; Tian, He; Wu, Y L; Zhu, L L; Tao, L Q; Zhang, W; Shu, Y; Xie, D; Yang, Y; Wei, Z Y; Lu, X H; Ren, Tian-Ling; Shih, Chih-Kang; Zhao, Jimin

    2015-01-01

    Many remarkable properties of graphene are derived from its large energy window for Dirac-like electronic states and have been explored for applications in electronics and photonics. In addition, strong electron-phonon interaction in graphene has led to efficient photo-thermo energy conversions, which has been harnessed for energy applications. By combining the wavelength independent absorption property and the efficient photo-thermo energy conversion, here we report a new type of applications in sound wave generation underlined by a photo-thermo-acoustic energy conversion mechanism. Most significantly, by utilizing ultrafast optical pulses, we demonstrate the ability to control the phase of sound waves generated by the photo-thermal-acoustic process. Our finding paves the way for new types of applications for graphene, such as remote non-contact speakers, optical-switching acoustic devices, etc. PMID:26053560

  5. Recent advances on pipe inspection using guided waves generated by electromagnetic acoustic transducers

    NASA Astrophysics Data System (ADS)

    Vasiljevic, Milos; Kundu, Tribikram; Grill, Wolfgang; Twerdowski, Evgeny

    2008-03-01

    For several years guided waves have been used for pipe wall defect detection. Guided waves have become popular for monitoring large structures because of the capability of these waves to propagate long distances along pipes, plates, interfaces and structural boundaries before loosing their strengths. The current technological challenges are to detect small defects in the pipe wall and estimate their dimensions using appropriate guided wave modes and to generate those modes relatively easily for field applications. Electro-Magnetic Acoustic Transducers (EMAT) can generate guided waves in pipes in the field environment. This paper shows how small defects in the pipe wall can be detected and their dimensions can be estimated by appropriate signal processing technique applied to the signals generated and received by the EMAT.

  6. Surface Generated Acoustic Wave Biosensors for the Detection of Pathogens: A Review

    PubMed Central

    Rocha-Gaso, María-Isabel; March-Iborra, Carmen; Montoya-Baides, Ángel; Arnau-Vives, Antonio

    2009-01-01

    This review presents a deep insight into the Surface Generated Acoustic Wave (SGAW) technology for biosensing applications, based on more than 40 years of technological and scientific developments. In the last 20 years, SGAWs have been attracting the attention of the biochemical scientific community, due to the fact that some of these devices - Shear Horizontal Surface Acoustic Wave (SH-SAW), Surface Transverse Wave (STW), Love Wave (LW), Flexural Plate Wave (FPW), Shear Horizontal Acoustic Plate Mode (SH-APM) and Layered Guided Acoustic Plate Mode (LG-APM) - have demonstrated a high sensitivity in the detection of biorelevant molecules in liquid media. In addition, complementary efforts to improve the sensing films have been done during these years. All these developments have been made with the aim of achieving, in a future, a highly sensitive, low cost, small size, multi-channel, portable, reliable and commercially established SGAW biosensor. A setup with these features could significantly contribute to future developments in the health, food and environmental industries. The second purpose of this work is to describe the state-of-the-art of SGAW biosensors for the detection of pathogens, being this topic an issue of extremely importance for the human health. Finally, the review discuses the commercial availability, trends and future challenges of the SGAW biosensors for such applications. PMID:22346725

  7. Effect of surface acoustic waves on the catalytic decomposition of ethanol employing a comb transducer for ultrasonic generation

    SciTech Connect

    S. J. Reese; D. H. Hurley; H.W. Rollins

    2006-04-01

    The effect of surface acoustic waves, generated on a silver catalyst using a comb transducer, on the catalytic decomposition of ethanol is examined. The comb transducer employs purely mechanical means for surface acoustic wave (SAW) transduction. Unlike interdigital SAW transducers on piezoelectric substrates, the complicating effects of heat generation due to electromechanical coupling, high electric fields between adjacent electrodes, and acoustoelectric currents are avoided. The ethanol decomposition reactions are carried out at 473 K. The rates of acetaldehyde and ethylene production are retarded when acoustic waves are applied. The rates recover to varying degrees when acoustic excitation ceases.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  9. Acoustic waves generated by pulsed microwaves in viscoelastic rods: modeling and experimental verification.

    PubMed

    Bacon, C; Guilliorit, E; Hosten, B; Chimenti, D E

    2001-09-01

    The acoustic wave generation in a specimen irradiated by a pulsed microwave is predicted theoretically. The specimen is a viscoelastic rod inserted into a wave guide. The model is based on Maxwell's equations, heat equation and thermoviscoelasticity theory. Computations show the presence of temperature oscillations due to the electromagnetic interferences in the irradiated rod if its electromagnetic absorption is low. An experimental method to infer indirectly the detailed behavior of microwave-generated acoustic waves in polymer rods, including the influence of electromagnetic wave reflection at the rod ends, is presented. The method consists of measuring the oscillations in the particle acceleration detected at the end of the rod that are induced by variations in the polymer rod length. The oscillations are caused by changing electromagnetic standing-wave conditions within the rod. It is found that these oscillations are in agreement in period, amplitude, and phase, with independent values of the complex dielectric constant and complex acoustic slowness of the polyvinyl chloride samples used in the study. PMID:11572350

  10. Surface Acoustic Wave Microfluidics

    NASA Astrophysics Data System (ADS)

    Yeo, Leslie Y.; Friend, James R.

    2014-01-01

    Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10-1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a diverse range of complex fluid transport phenomena - from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization - underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions.

  11. Three-dimensional visualization of shear wave propagation generated by dual acoustic radiation pressure

    NASA Astrophysics Data System (ADS)

    Mochizuki, Yuta; Taki, Hirofumi; Kanai, Hiroshi

    2016-07-01

    An elastic property of biological soft tissue is an important indicator of the tissue status. Therefore, quantitative and noninvasive methods for elasticity evaluation have been proposed. Our group previously proposed a method using acoustic radiation pressure irradiated from two directions for elastic property evaluation, in which by measuring the propagation velocity of the shear wave generated by the acoustic radiation pressure inside the object, the elastic properties of the object were successfully evaluated. In the present study, we visualized the propagation of the shear wave in a three-dimensional space by the synchronization of signals received at various probe positions. The proposed method succeeded in visualizing the shear wave propagation clearly in the three-dimensional space of 35 × 41 × 4 mm3. These results show the high potential of the proposed method to estimate the elastic properties of the object in the three-dimensional space.

  12. Acoustic waves in the atmosphere and ground generated by volcanic activity

    SciTech Connect

    Ichihara, Mie; Lyons, John; Oikawa, Jun; Takeo, Minoru

    2012-09-04

    This paper reports an interesting sequence of harmonic tremor observed in the 2011 eruption of Shinmoe-dake volcano, southern Japan. The main eruptive activity started with ashcloud forming explosive eruptions, followed by lava effusion. Harmonic tremor was transmitted into the ground and observed as seismic waves at the last stage of the effusive eruption. The tremor observed at this stage had unclear and fluctuating harmonic modes. In the atmosphere, on the other hand, many impulsive acoustic waves indicating small surface explosions were observed. When the effusion stopped and the erupted lava began explosive degassing, harmonic tremor started to be transmitted also to the atmosphere and observed as acoustic waves. Then the harmonic modes became clearer and more stable. This sequence of harmonic tremor is interpreted as a process in which volcanic degassing generates an open connection between the volcanic conduit and the atmosphere. In order to test this hypothesis, a laboratory experiment was performed and the essential features were successfully reproduced.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  14. Electromagnetic acoustic source (EMAS) for generating shock waves and cavitation in mercury

    NASA Astrophysics Data System (ADS)

    Wang, Qi

    In the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory a vessel of liquid mercury is subjected to a proton beam. The resulting nuclear interaction produces neutrons that can be used for materials research, among other things, but also launches acoustic waves with pressures in excess of 10 MPa. The acoustic waves have high enough tensile stress to generate cavitation in the mercury which results in erosion to the steel walls of the vessel. In order to study the cavitation erosion and develop mitigation schemes it would be convenient to have a way of generating similar pressures and cavitation in mercury, without the radiation concerns associated with a proton beam. Here an electromagnetic acoustic source (EMAS) has been developed which consisted of a coil placed close to a metal plate which is in turn is in contact with a fluid. The source is driven by discharging a capacitor through the coil and results in a repulsive force on the plate launching acoustic waves in the fluid. A theoretical model is presented to predict the acoustic field from the EMAS and compares favorably with measurements made in water. The pressure from the EMAS was reported as a function of capacitance, charging voltage, number of coils, mylar thickness, and properties of the plates. The properties that resulted in the highest pressure were employed for experiments in mercury and a maximum pressure recorded was 7.1 MPa. Cavitation was assessed in water and mercury by high speed camera and by detecting acoustic emissions. Bubble clouds with lifetimes on the order of 100 µs were observed in water and on the order of 600 µs in mercury. Based on acoustic emissions the bubble radius in mercury was estimated to be 0.98 mm. Experiments to produce damage to a stainless steel plate in mercury resulted in a minimal effect after 2000 shock waves at a rate of 0.33 Hz - likely because the pressure amplitude was not high enough. In order to replicate the conditions in the SNS it is

  15. Acoustic source for generating an acoustic beam

    DOEpatents

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

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  16. Temperature dependence of acoustic harmonics generated by nonlinear ultrasound wave propagation in water at various frequencies.

    PubMed

    Maraghechi, Borna; Hasani, Mojtaba H; Kolios, Michael C; Tavakkoli, Jahan

    2016-05-01

    Ultrasound-based thermometry requires a temperature-sensitive acoustic parameter that can be used to estimate the temperature by tracking changes in that parameter during heating. The objective of this study is to investigate the temperature dependence of acoustic harmonics generated by nonlinear ultrasound wave propagation in water at various pulse transmit frequencies from 1 to 20 MHz. Simulations were conducted using an expanded form of the Khokhlov-Zabolotskaya-Kuznetsov nonlinear acoustic wave propagation model in which temperature dependence of the medium parameters was included. Measurements were performed using single-element transducers at two different transmit frequencies of 3.3 and 13 MHz which are within the range of frequencies simulated. The acoustic pressure signals were measured by a calibrated needle hydrophone along the axes of the transducers. The water temperature was uniformly increased from 26 °C to 46 °C in increments of 5 °C. The results show that the temperature dependence of the harmonic generation is different at various frequencies which is due to the interplay between the mechanisms of absorption, nonlinearity, and focusing gain. At the transmit frequencies of 1 and 3.3 MHz, the harmonic amplitudes decrease with increasing the temperature, while the opposite temperature dependence is observed at 13 and 20 MHz. PMID:27250143

  17. Generation of ion-acoustic waves in an inductively coupled, low-pressure discharge lamp

    SciTech Connect

    Camparo, J. C.; Klimcak, C. M.

    2006-04-15

    For a number of years it has been known that the alkali rf-discharge lamps used in atomic clocks can exhibit large amplitude intensity oscillations. These oscillations arise from ion-acoustic plasma waves and have typically been associated with erratic clock behavior. Though large amplitude ion-acoustic plasma waves are clearly deleterious for atomic clock operation, it does not follow that small amplitude oscillations have no utility. Here, we demonstrate two easily implemented methods for generating small amplitude ion-acoustic plasma waves in alkali rf-discharge lamps. Furthermore, we demonstrate that the frequency of these waves is proportional to the square root of the rf power driving the lamp and therefore that their examination can provide an easily accessible parameter for monitoring and controlling the lamp's plasma conditions. This has important consequences for precise timekeeping, since the atomic ground-state hyperfine transition, which is the heart of the atomic clock signal, can be significantly perturbed by changes in the lamp's output via the ac-Stark shift.

  18. Optimal shaping of acoustic resonators for the generation of high-amplitude standing waves.

    PubMed

    Červenka, Milan; Šoltés, Martin; Bednařík, Michal

    2014-09-01

    Within this paper, optimal shaping of acoustic resonators for the generation of high-amplitude standing waves through the use of evolutionary algorithms is discussed. The resonator shapes are described using sets of control points interconnected with cubic-splines. Positions of the control points are calculated by means of an evolutionary algorithm in order to maximize acoustic pressure amplitude at a given point of the resonator cavity. As an objective function for the optimization procedure, numerical solution of one-dimensional linear wave equation taking into account boundary-layer dissipation is used. Resonator shapes maximizing acoustic pressure amplitude are found in case of a piston, shaker, or loudspeaker driving. It is shown that the optimum resonator shapes depend on the method of driving. In all the cases, acoustic field attains higher amplitude in the optimized resonators than in simple-shaped non-optimized resonators of similar dimensions. Theoretical results are compared with experimental data in the case of a loudspeaker driving, good agreement of which is achieved. PMID:25190376

  19. Coherent Generation of Photo-Thermo-Acoustic Wave from Graphene Sheets

    NASA Astrophysics Data System (ADS)

    Tian, Yichao; Tian, He; Wu, Yanling; Zhu, Leilei; Tao, Luqi; Zhang, Wei; Shu, Yi; Xie, Dan; Yang, Yi; Wei, Zhiyi; Lu, Xinghua; Ren, Tian-Ling; Shih, Chih-Kang; Zhao, Jimin

    Many remarkable properties of graphene are derived from its large energy window for Dirac-like electronic states and have been explored for applications in electronics and photonics. In addition, strong electron-phonon interaction in graphene has led to efficient photo-thermo energy conversions, which has been harnessed for energy applications. By combining the wavelength independent absorption property and the efficient photo-thermo energy conversion, here we report a new type of applications in sound wave generation underlined by a photo-thermo-acoustic energy conversion mechanism. Most significantly, by utilizing ultrafast optical pulses, we demonstrate the ability to control the phase of sound waves generated by the photo-thermal-acoustic process. Our finding paves the way for new types of applications for graphene, such as remote non-contact speakers, optical-switching acoustic devices, etc. National Basic Research Program of China MOST (2012CB821402), External Cooperation Program of Chinese Academy of Sciences (GJHZ1403), and National Natural Science Foundation of China (11274372).

  20. Features of Propagation of the Acoustic-Gravity Waves Generated by High-Power Periodic Radiation

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.; Frolov, V. L.

    2013-09-01

    We present the results of the bandpass filtering of temporal variations of the Doppler frequency shift of radio signals from a vertical-sounding Doppler radar located near the city of Kharkov when the ionosphere was heated by high-power periodic (with 10 and 15-min periods) radiation from the Sura facility. The filtering was done in the ranges of periods that are close to the acoustic cutoff period and the Brunt—Väisälä period (4-6, 8-12, and 13-17 min). Oscillations with periods of 4-6 min and amplitudes of 50-100 mHz were not recorded in fact. Oscillations with periods of 8-12 and 13-17 min and amplitudes of 60-100 mHz were detected in almost all the sessions. In the former and the latter oscillations, the time of delay with respect to the heater switch-on was close to 100 min and about 40-50 min, respectively. These values correspond to group propagation velocities of about 160 and 320-400 m/s. The Doppler shift oscillations were caused by the acoustic-gravity waves which led to periodic variations in the electron number density with a relative amplitude of about 0.1-1.0%. It was demonstrated that the acoustic-gravity waves were not recorded when the effective power of the Sura facility was equal to 50 MW and they were confidently observed when the effective power was increased up to 130 MW. It is shown that the period of the wave processes was determined by the period of the heating-pause cycles, and the duration of the wave trains did not depend on the duration of the series of heating-pause cycles. The data suggest that the generation mechanism of recorded wave disturbances is different from the mechanism proposed in 1970-1990.

  1. Soliton generation via continuous stokes acoustic self-scattering of hypersonic waves in a paramagnetic crystal

    SciTech Connect

    Bugay, A. N.; Sazonov, S. V.

    2008-08-15

    A new mechanism is proposed for continuous frequency down-conversion of acoustic waves propagating in a paramagnetic crystal at a low temperature in an applied magnetic field. A transverse hypersonic pulse generating a carrier-free longitudinal strain pulse via nonlinear effects is scattered by the generated pulse. This leads to a Stokes shift in the transverse hypersonic wave proportional to its intensity, and both pulses continue to propagate in the form of a mode-locked soliton. As the transverse-pulse frequency is Stokes shifted, its spectrum becomes narrower. This process can be effectively implemented only if the linear group velocity of the transverse hypersonic pulse equals the phase velocity of the longitudinal strain wave. These velocities are renormalized by spin-phonon coupling and can be made equal by adjusting the magnitude of the applied magnetic field. The transverse structure of the soliton depends on the sign of the group velocity dispersion of the transverse component. When the dispersion is positive, planar solitons can develop whose transverse component has a topological defect of dark vortex type and longitudinal component has a hole. In the opposite case, the formation of two-component acoustic 'bullets' or vortices localized in all directions is possible.

  2. Generation of Artificial Acoustic-Gravity Waves and Traveling Ionospheric Disturbances in HF Heating Experiments

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Lee, M. C.; Cohen, J. A.; Watkins, B. J.

    2015-10-01

    We report the results of our ionospheric HF heating experiments to generate artificial acoustic-gravity waves (AGW) and traveling ionospheric disturbances (TID), which were conducted at the High-frequency Active Auroral Research Program facility in Gakona, Alaska. Based on the data from UHF radar, GPS total electron content, and ionosonde measurements, we found that artificial AGW/TID can be generated in ionospheric modification experiments by sinusoidally modulating the power envelope of the transmitted O-mode HF heater waves. In this case, the modulation frequency needs to be set below the characteristic Brunt-Vaisala frequency at the relevant altitudes. We avoided potential contamination from naturally-occurring AGW/TID of auroral origin by conducting the experiments during geomagnetically quiet time period. We determine that these artificial AGW/TID propagate away from the edge of the heated region with a horizontal speed of approximately 160 m/s.

  3. Acoustic waves generated by a laser point pulse in a transversely isotropic cylinder.

    PubMed

    Pan, Y; Perton, M; Audoin, B; Rossignol, C

    2006-01-01

    A three-dimensional (3D) model is presented to predict the acoustic waves generated by a laser point pulse in a transversely isotropic cylinder. The Fourier series expansion and the two-dimensional Fourier transform are introduced to calculate the 3D transient response under either the ablation or the thermoelastic generation. The presented physical model and the numerical inverse scheme are applied to a fiber reinforced composite cylinder with a strong anisotropy. Experimental radial displacements of the cylinder surface are detected by the laser ultrasonic technique and analyzed by the ray trajectories for both generation regimes. Corresponding theoretical displacements are obtained numerically and compared to the experimental signals. Good agreement is found between theoretical and experimental results. The focusing effects that anisotropy gives rise to are observed in both theory and experiment under either regime. PMID:16454280

  4. Generation of acoustic waves by focused infrared neodymium-laser radiation

    NASA Astrophysics Data System (ADS)

    Ward, Barry

    1991-02-01

    When the radiation from a sufficiently powerful pulsed laser is focused into the transparent gaseous, liquid or solid media, dielectric breakdown may occur around the beam waist giving rise to a short-lived high-temperature plasma which quickly heats the surrounding material. As a consequence of various energy-coupling mechanisms, this phenomenon causes the emission of one or more high-frequency ultrasonic acoustic waves whose speeds of propagation are dependent upon the physical properties of the host medium. In the high-speed photographic studies described, the 1.06 micron near-infrared radiation from an 8-ns, 10-mJ Q-switched Nd:YAG laser is focused in or onto a variety of fluid and solid materials. The rapid variations in density around the resulting plasma events are visualized using a Mach-Zehnder interferometer with a sub-nanosecond dye-laser light source and a video-imaging system. Calculations of the corresponding transient pressure distributions are then enacted from the digitally-recorded interferograms using a semi-automatic procedure under the control of a personal computer. Measurements of position, displacement, and velocity are also carried out using the same optical apparatus in schlieren and focused shadowgraph high-speed photographic measurements. The experimental work outlined in the following chapters is divided into three broad fields of interest. In the first of these, a study of the laser-generation of spherical shock waves in atmospheric air is carried out. In the second, the neodymium-laser beam is focused onto different solid-fluid interfaces resulting in the formation of bulk longitudinal and shear waves and surface acoustic waves. The interactions of these waves with various obstacles and defects are investigated with reference to their application to non-destructive testing. In the third and most important field, a detailed study of the dynamics of laser-induced cavitation bubbles in water is carried out. With regard to the associated

  5. Generation and detection of gigahertz surface acoustic waves using an elastomeric phase-shift mask

    NASA Astrophysics Data System (ADS)

    Li, Dongyao; Zhao, Peng; Zhao, Ji-Cheng; Cahill, David G.

    2013-10-01

    We describe a convenient approach for measuring the velocity vSAW of surface acoustic waves (SAWs) of the near-surface layer of a material through optical pump-probe measurements. The method has a lateral spatial resolution of <10 μm and is sensitive to the elastic constants of the material within ≈300 nm of the surface. SAWs with a wavelength of 700 nm and 500 nm are generated and detected using an elastomeric polydimethylsiloxane phase-shift mask which is fabricated using a commercially available Si grating as a mold. Time-domain electromagnetics calculations show, in agreement with experiment, that the efficiency of the phase-shift mask for generating and detecting SAWs decreases rapidly as the periodicity of the mask decreases below the optical wavelength. We validate the experimental approach using bulk and thin film samples with known elastic constants.

  6. FE simulation of laser generated surface acoustic wave propagation in skin.

    PubMed

    L'Etang, Adèle; Huang, Zhihong

    2006-12-22

    Advances in laser ultrasonics have opened new possibilities in medical applications, such as the characterization of skin properties. This paper describes the development of a multilayered finite element model (FEM) using ANSYS to simulate the propagation of laser generated thermoelastic surface acoustic waves (SAWs) through skin and to generate signals one would expect to observe without causing thermal damage to skin. A transient thermal analysis is developed to simulate the thermal effect of the laser source penetrating into the skin. The results from the thermal analysis are subsequently applied as a load to the structural analysis where the out-of-plane displacement responses are analysed in models with varying dermis layer thickness. PMID:16814352

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

    PubMed

    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

  8. Generation and Radiation of Acoustic Waves from a 2D Shear Layer

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D.

    2000-01-01

    A thin free shear layer containing an inflection point in the mean velocity profile is inherently unstable. Disturbances in the flow field can excite the unstable behavior of a shear layer, if the appropriate combination of frequencies and shear layer thicknesses exists, causing instability waves to grow. For other combinations of frequencies and thicknesses, these instability waves remain neutral in amplitude or decay in the downstream direction. A growing instability wave radiates noise when its phase velocity becomes supersonic relative to the ambient speed of sound. This occurs primarily when the mean jet flow velocity is supersonic. Thus, the small disturbances in the flow, which themselves may generate noise, have generated an additional noise source. It is the purpose of this problem to test the ability of CAA to compute this additional source of noise. The problem is idealized such that the exciting disturbance is a fixed known acoustic source pulsating at a single frequency. The source is placed inside of a 2D jet with parallel flow; hence, the shear layer thickness is constant. With the source amplitude small enough, the problem is governed by the following set of linear equations given in dimensional form.

  9. Generation and Upper Atmospheric Propagation of Acoustic Gravity Waves according to Numerical Modeling and Radio Tomography

    NASA Astrophysics Data System (ADS)

    Vorontsov, Artem; Andreeva, Elena; Nesterov, Ivan; Padokhin, Artem; Kurbatov, Grigory

    2016-04-01

    The acoustic-gravity waves (AGW) in the upper atmosphere and ionosphere can be generated by a variety of the phenomena in the near-Earth environment and atmosphere as well as by some perturbations of the Earth's ground or ocean surface. For instance, the role of the AGW sources can be played by the earthquakes, explosions, thermal heating, seisches, tsunami waves. We present the examples of AGWs excited by the tsunami waves traveling in the ocean, by seisches, and by ionospheric heating by the high-power radio wave. In the last case, the gravity waves are caused by the pulsed modulation of the heating wave. The AGW propagation in the upper atmosphere induces the variations and irregularities in the electron density distribution of the ionosphere, whose structure can be efficiently reconstructed by the method of the ionospheric radio tomography (RT) based on the data from the global navigational satellite systems (GNSS). The input data for RT diagnostics are composed of the 150/400 MHz radio signals from the low-orbiting (LO) satellites and 1.2-1.5 GHz radio signals from the high-orbiting (HO) satellites with their orbits at ~1000 and ~20000 km above the ground, respectively. These data enable ionospheric imaging on different spatiotemporal scales with different spatiotemporal resolution and coverage, which is suitable, inter alia, for tracking the waves and wave-like features in the ionosphere. In particular, we demonstrate the maps of the ionospheric responses to the tornado at Moore (Oklahoma, USA) of May 20, 2013, which are reconstructed from the HO data. We present the examples of LORT images containing the waves and wavelike disturbances associated with various sources (e.g., auroral precipitation and high-power heating of the ionosphere). We also discuss the results of modeling the AGW generation by the surface and volumetric sources. The millihertz AGW from these sources initiate the ionospheric perturbation with a typical scale of a few hundred km at the

  10. Numerical analysis of wave generation and propagation in a focused surface acoustic wave device for potential microfluidics applications.

    PubMed

    Sankaranarayanan, Subramanian K R S; Bhethanabotla, Venkat R

    2009-03-01

    We develop a 3-D finite element model of a focused surface acoustic wave (F-SAW) device based on LiNbO(3) to analyze the wave generation and propagation characteristics for devices operating at MHz frequencies with varying applied input voltages. We compare the F-SAW device to a conventional SAW device with similar substrate dimensions and transducer finger periodicity. SAW devices with concentrically shaped focused interdigital transducer fingers (F-IDTs) are found to excite waves with high intensity and high beam-width compression ratio, confined to a small localized area. F-SAW devices are more sensitive to amplitude variations at regions close to the focal point than conventional SAW devices having uniform IDT configuration. We compute F-SAW induced streaming forces and velocity fields by applying a successive approximation technique to the Navier-Stokes equation (Nyborg's theory). The maximum streaming force obtained at the focal point varies as the square of the applied input voltage. Computed streaming velocities at the focal point in F-SAW devices are at least an order of magnitude higher than those in conventional SAW devices. Simulated frequency response indicates higher insertion losses in F-SAW devices than in conventional devices, reflecting their greater utility as actuators than as sensors. Our simulation findings suggest that F-SAW devices can be utilized effectively for actuation in microfluidic applications involving diffusion limited transport processes. PMID:19411221

  11. Simulation study of melanoma detection in human skin tissues by laser-generated surface acoustic waves.

    PubMed

    Chen, Kun; Fu, Xing; Dorantes-Gonzalez, Dante J; Lu, Zimo; Li, Tingting; Li, Yanning; Wu, Sen; Hu, Xiaotang

    2014-01-01

    Air pollution has been correlated to an increasing number of cases of human skin diseases in recent years. However, the investigation of human skin tissues has received only limited attention, to the point that there are not yet satisfactory modern detection technologies to accurately, noninvasively, and rapidly diagnose human skin at epidermis and dermis levels. In order to detect and analyze severe skin diseases such as melanoma, a finite element method (FEM) simulation study of the application of the laser-generated surface acoustic wave (LSAW) technique is developed. A three-layer human skin model is built, where LSAW’s are generated and propagated, and their effects in the skin medium with melanoma are analyzed. Frequency domain analysis is used as a main tool to investigate such issues as minimum detectable size of melanoma, filtering spectra from noise and from computational irregularities, as well as on how the FEM model meshing size and computational capabilities influence the accuracy of the results. Based on the aforementioned aspects, the analysis of the signals under the scrutiny of the phase velocity dispersion curve is verified to be a reliable, a sensitive, and a promising approach for detecting and characterizing melanoma in human skin. PMID:25057963

  12. Thin film interface stresses produced by high amplitude laser generated surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Sherman, Bradley; Liou, Hong-Cin; Balogun, Oluwaseyi

    2015-10-01

    Surface acoustic waves (SAWs) have been explored for nondestructive metrology of thin film elastic properties and thickness due to confinement of their energy within a shallow depth from a material surface. In this paper, we study the dynamic interfacial stresses produced by high amplitude SAWs generated by a strongly ablative source in a thin film-substrate system, with the goal of investigating the possibility of inducing thin film delamination at high loading rates. For modeling purposes, we represent the mechanical loading resulting from the pulsed laser-sample interaction in the ablative regime by an equivalent compressive surface load, and the resulting stresses and particle velocities induced by the generated SAWs are calculated using a linear finite element model. We explore the numerical model to study the dependence of the film-substrate interface tractions on the ratio of the film thickness and SAW wavelength for a soft film on a stiff substrate. Furthermore, by matching the numerical results obtained from the finite element model with experimental results, we are able to predict the dynamic interfacial stresses for a copper film on a fused silica substrate produced by SAWs excited by a high power pulsed laser line source. This study has implications for exploring SAWs in the characterization of interfacial failure in thin-film substrate systems.

  13. Simulation study of melanoma detection in human skin tissues by laser-generated surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Chen, Kun; Fu, Xing; Dorantes-Gonzalez, Dante J.; Lu, Zimo; Li, Tingting; Li, Yanning; Wu, Sen; Hu, Xiaotang

    2014-07-01

    Air pollution has been correlated to an increasing number of cases of human skin diseases in recent years. However, the investigation of human skin tissues has received only limited attention, to the point that there are not yet satisfactory modern detection technologies to accurately, noninvasively, and rapidly diagnose human skin at epidermis and dermis levels. In order to detect and analyze severe skin diseases such as melanoma, a finite element method (FEM) simulation study of the application of the laser-generated surface acoustic wave (LSAW) technique is developed. A three-layer human skin model is built, where LSAW's are generated and propagated, and their effects in the skin medium with melanoma are analyzed. Frequency domain analysis is used as a main tool to investigate such issues as minimum detectable size of melanoma, filtering spectra from noise and from computational irregularities, as well as on how the FEM model meshing size and computational capabilities influence the accuracy of the results. Based on the aforementioned aspects, the analysis of the signals under the scrutiny of the phase velocity dispersion curve is verified to be a reliable, a sensitive, and a promising approach for detecting and characterizing melanoma in human skin.

  14. Acoustic and electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Jones, Douglas Samuel

    Theoretical models of EM and acoustic wave propagation are presented in an introductory text intended for intermediate-level science and engineering students. Chapters are devoted to the mathematical representation of acoustic and EM fields, the special theory of relativity, radiation, resonators, waveguide theory, refraction, surface waves, scattering by smooth objects, diffraction by edges, and transient waves. The mathematical tools required for the analysis (Bessel, Legendre, Mathieu, parabolic-cylinder, and spheroidal functions; tensor calculus; and the asymptotic evaluation of integrals) are covered in appendices.

  15. Generation and Radiation of Acoustic Waves from a 2-D Shear Layer using the CE/SE Method

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Wang, Xiao Y.; Chang, Sin-Chung; Jorgenson, Philip C. E.

    2000-01-01

    In the present work, the generation and radiation of acoustic waves from a 2-D shear layer problem is considered. An acoustic source inside of a 2-D jet excites an instability wave in the shear layer, resulting in sound Mach radiation. The numerical solution is obtained by solving the Euler equations using the space time conservation element and solution element (CE/SE) method. Linearization is achieved through choosing a small acoustic source amplitude. The Euler equations are nondimensionalized as instructed in the problem statement. All other conditions are the same except that the Crocco's relation has a slightly different form. In the following, after a brief sketch of the CE/SE method, the numerical results for this problem are presented.

  16. Identification of laser generated acoustic waves in the two-dimensional transient response of cylinders

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Rossignol, C.; Audoin, B.

    2005-06-01

    The published model [Appl. Phys. Lett. 82, 4379-4381 (2003)] for the two-dimensional transient wave propagation in a cylinder is modified to avoid the inherited integration of the numerical inverse scheme. The Fourier series expansion is introduced for one spatial coordinate to resolve the transient response problem: theoretical radial displacements in either the ablation or the thermoelastic regime are obtained with little numerical noise and short computation time. The normal mode expansion method fails to deliver results with the same accuracy. Acoustic waves are fully identified by the ray trajectory analysis. These identified waves are further verified on the experimental results observed with the laser ultrasonic technique. .

  17. Hydro-acoustic and tsunami waves generated by the 2012 Haida Gwaii earthquake: Modeling and in situ measurements

    NASA Astrophysics Data System (ADS)

    Abdolali, Ali; Cecioni, Claudia; Bellotti, Giorgio; Kirby, James T.

    2015-02-01

    Detection of low-frequency hydro-acoustic waves as precursor components of destructive tsunamis can enhance the promptness and the accuracy of Tsunami Early Warning Systems (TEWS). We reconstruct the hydro-acoustic wave field generated by the 2012 Haida Gwaii tsunamigenic earthquake using a 2-D horizontal numerical model based on the integration over the depth of the compressible fluid wave equation and considering a mild sloped rigid seabed. Spectral analysis of the wave field obtained at different water depths and distances from the source revealed the frequency range of low-frequency elastic oscillations of sea water. The resulting 2-D numerical model gave us the opportunity to study the hydro-acoustic wave propagation in a large-scale domain with available computers and to support the idea of deep-sea observatory and data interpretation. The model provides satisfactory results, compared with in situ measurements, in the reproduction of the long-gravitational waves. Differences between numerical results and field data are probably due to the lack of exact knowledge of sea bottom motion and to the rigid seabed approximation, indicating the need for further study of poro-elastic bottom effects.

  18. Cylindrical vector beam generation in fiber with mode selectivity and wavelength tunability over broadband by acoustic flexural wave.

    PubMed

    Zhang, Wending; Huang, Ligang; Wei, Keyan; Li, Peng; Jiang, Biqiang; Mao, Dong; Gao, Feng; Mei, Ting; Zhang, Guoquan; Zhao, Jianlin

    2016-05-16

    Theoretical analysis and experimental demonstration are presented for the generation of cylindrical vector beams (CVBs) via mode conversion in fiber from HE11 mode to TM01 and TE01 modes, which have radial and azimuthal polarizations, respectively. Intermodal coupling is caused by an acoustic flexural wave applied on the fiber, whereas polarization control is necessary for the mode conversion, i.e. HE11x→TM01 and HE11y→TE01 for acoustic vibration along the x-axis. The frequency of the RF driving signal for actuating the acoustic wave is determined by the phase matching condition that the period of acoustic wave equals the beatlength of two coupled modes. With phase matching condition tunability, this approach can be used to generate different types of CVBs at the same wavelength over a broadband. Experimental demonstration was done in the visible and communication bands. PMID:27409861

  19. Comparison with Analytical Solution: Generation and Radiation of Acoustic Waves from a 2-D Shear Layer

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D.

    2000-01-01

    An acoustic source inside of a 2-D jet excites an instability wave in the shear layer resulting in sound radiating away from the shear layer. Solve the linearized Euler equations to predict the sound radiation outside of the jet. The jet static pressure is assumed to be constant. The jet flow is parallel and symmetric about the x-axis. Use a symmetry boundary condition along the x-axis.

  20. Effects of interface bonding on acoustic wave generation in an elastic body by surface-mounted piezoelectric transducers.

    PubMed

    Li, Peng; Jin, Feng; Chen, Weiqiu; Yang, Jiashi

    2013-09-01

    We study the effects of interface bonding on acoustic wave generation in an elastic body using surface-mounted piezoelectric transducers driven electrically. A theoretical analysis is performed based on a physical model of a piezoelectric layer on an elastic substrate. The transducer-substrate interface is described by the shear-slip model, representing a viscoelastic interface. Different from the results in the literature on free vibrations of structures with weak interfaces, this paper presents an electrically forced vibration analysis. An analytical solution for the generated acoustic wave is obtained and used to calculate its energy flux and the efficiency of the transduction. The effects of the interface parameters are examined. It is found that the interface bonding affects the performance of the transducer in multiple ways, some of which may be exploitable in designs for better transducer performance. In particular, optimal transduction is not necessarily associated with a perfectly bonded interface. PMID:24658726

  1. Acoustic-gravity waves generated by atmospheric and near-surface sources

    NASA Astrophysics Data System (ADS)

    Kunitsyn, Viacheslav E.; Kholodov, Alexander S.; Krysanov, Boris Yu.; Andreeva, Elena S.; Nesterov, Ivan A.; Vorontsov, Artem M.

    2013-04-01

    Numerical simulation of the acoustic-gravity waves (AGW) generated by long-period oscillations of the Earth's (oceanic) surface, earthquakes, explosions, thermal heating, seiches, and tsunami is carried out. Wavelike disturbances are quite frequent phenomena in the atmosphere and ionosphere. These events can be caused by the impacts from space and atmosphere, by oscillations of the Earth'as surface and other near-surface events. These wavelike phenomena in the atmosphere and ionosphere appear as the alternating areas of enhanced and depleted density (in the atmosphere) or electron concentration (in the ionosphere). In the paper, AGW with typical frequencies of a few hertz - millihertz are analyzed. AGW are often observed after the atmospheric perturbations, during the earthquakes, and some time (a few days to hours) in advance of the earthquakes. Numerical simulation of the generation of AGW by long-period oscillations of the Earth's and oceanic surface, earthquakes, explosions, thermal heating, seiches, and tsunami is carried out. The AGW generated by the near-surface phenomena within a few hertz-millihertz frequency range build up at the mid-atmospheric and ionospheric altitudes, where they assume their typical spatial scales of the order of a few hundred kilometers. Oscillations of the ionospheric plasma within a few hertz-millihertz frequency range generate electromagnetic waves with corresponding frequencies as well as travelling ionospheric irregularities (TIDs). Such structures can be successfully monitored using satellite radio tomography (RT) techniques. For the purposes of RT diagnostics, 150/400 MHz transmissions from low-orbiting navigational satellites flying in polar orbits at the altitudes of about 1000 km as well as 1.2-1.5 GHz signals form high-orbiting (orbital altitudes about 20000 km) navigation systems like GPS/GLONASS are used. The results of experimental studies on generation of wavelike disturbances by particle precipitation are presented

  2. Generation of Acoustic Gravity Waves by Periodic Radio Transmissions from a High-Power Ionospheric Heater

    NASA Astrophysics Data System (ADS)

    Frolov, Vladimir; Chernogor, Leonid; Rozumenko, Victor

    The Radiophysical Research Institute (Nizhny Novgorod, Russia) and Kharkiv V. N. Karazin National University (Kharkiv, Ukraine) have studied opportunities for the effective generation of acoustic gravity waves (AGWs) in 3 - 180-min period range. The excitation of such waves was conducted for the last several years using the SURA heating facility (Nizhny Novgorod). The detection of the HF-induced AGWs was carried out in the Radiophysical Observatory located near Kharkiv City at a distance of about 960 km from the SURA. A coherent radar for vertical sounding, an ionosonde, and magnetometer chains were used in our measurements. The main results are the following (see [1-5]): 1. Infrasound oscillation trains with a period of 6 min are detected during periodic SURA heater turn-on and -off. Similar oscillation trains are detected after long time pumping, during periodic transmissions with a period of 20 s, as well as after pumping turn-off. The train recordings begin 28 - 54 min after the heater turn-on or -off, and the train propagation speeds are about 300 - 570 m/s, the value of which is close to the sound speed at upper atmospheric altitudes. The amplitude of the Doppler shift frequency is of 10 - 40 mHz, which fits to the 0.1 - 0.3% electron density disturbances at ionospheric altitudes. The amplitude of the infrasound oscillations depends on the SURA mode of operation and the state of the upper atmosphere and ionosphere. 2. High-power radio transmissions stimulate the generation (or enhancement) of waves at ionospheric altitudes in the range of internal gravity wave periods. The HF-induced waves propagate with speeds of 360 - 460 m/s and produce changes in electron density with amplitudes of 2 - 3%. The generation of such periodic perturbations is more preferable with periods of 10 - 60 minutes. Their features depend significantly on the heater mode of operation. It should be stressed that perturbation intensity increases when a pumping wave frequency approaches

  3. A numerical model for ocean ultra-low frequency noise: wave-generated acoustic-gravity and Rayleigh modes.

    PubMed

    Ardhuin, Fabrice; Lavanant, Thibaut; Obrebski, Mathias; Marié, Louis; Royer, Jean-Yves; d'Eu, Jean-François; Howe, Bruce M; Lukas, Roger; Aucan, Jerome

    2013-10-01

    The generation of ultra-low frequency acoustic noise (0.1 to 1 Hz) by the nonlinear interaction of ocean surface gravity waves is well established. More controversial are the quantitative theories that attempt to predict the recorded noise levels and their variability. Here a single theoretical framework is used to predict the noise level associated with propagating pseudo-Rayleigh modes and evanescent acoustic-gravity modes. The latter are dominant only within 200 m from the sea surface, in shallow or deep water. At depths larger than 500 m, the comparison of a numerical noise model with hydrophone records from two open-ocean sites near Hawaii and the Kerguelen islands reveal: (a) Deep ocean acoustic noise at frequencies 0.1 to 1 Hz is consistent with the Rayleigh wave theory, in which the presence of the ocean bottom amplifies the noise by 10 to 20 dB; (b) in agreement with previous results, the local maxima in the noise spectrum support the theoretical prediction for the vertical structure of acoustic modes; and (c) noise level and variability are well predicted for frequencies up to 0.4 Hz. Above 0.6 Hz, the model results are less accurate, probably due to the poor estimation of the directional properties of wind-waves with frequencies higher than 0.3 Hz. PMID:24116520

  4. Fast acoustic streaming in standing waves: generation of an additional outer streaming cell.

    PubMed

    Reyt, Ida; Daru, Virginie; Bailliet, Hélène; Moreau, Solène; Valière, Jean-Christophe; Baltean-Carlès, Diana; Weisman, Catherine

    2013-09-01

    Rayleigh streaming in a cylindrical acoustic standing waveguide is studied both experimentally and numerically for nonlinear Reynolds numbers from 1 to 30 [Re(NL)=(U0/c0)(2)(R/δν)(2), with U0 the acoustic velocity amplitude at the velocity antinode, c0 the speed of sound, R the tube radius, and δν the acoustic boundary layer thickness]. Streaming velocity is measured by means of laser Doppler velocimetry in a cylindrical resonator filled with air at atmospheric pressure at high intensity sound levels. The compressible Navier-Stokes equations are solved numerically with high resolution finite difference schemes. The resonator is excited by shaking it along the axis at imposed frequency. Results of measurements and of numerical calculation are compared with results given in the literature and with each other. As expected, the axial streaming velocity measured and calculated agrees reasonably well with the slow streaming theory for small ReNL but deviates significantly from such predictions for fast streaming (ReNL>1). Both experimental and numerical results show that when ReNL is increased, the center of the outer streaming cells are pushed toward the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes. PMID:23967913

  5. Laser generation and detection of surface acoustic waves - Elastic properties of surface layers

    NASA Astrophysics Data System (ADS)

    Neubrand, A.; Hess, P.

    1992-01-01

    A noncontact all-optical method for surface photoacoustics is described. The surface acoustic waves (SAWs) were excited employing a KrF laser and detected with a Michelson interferometer using a 633-nm HeNe laser. Due to an active stabilization scheme developed for the interferometer a surface displacement of 0.2 A could be detected. The materials investigated included pure materials such as polycrystalline aluminum, and crystalline silicon; films of gold, silver, aluminum, iron, and nickel on fused silica; and a Si:H on Si(100). In the case of pure materials the shape of the acoustic pulse and the phase velocity were determined. The dispersion of the SAW phase velocity observed for the film systems was used to extract information on the film thickness, density, and transverse and longitudinal sound velocity. Models for the theoretical treatment of film systems and the calculation of dispersion curves are presented.

  6. Nonlinear propagation of spark-generated N-waves in air: modeling and measurements using acoustical and optical methods.

    PubMed

    Yuldashev, Petr; Ollivier, Sébastien; Averiyanov, Mikhail; Sapozhnikov, Oleg; Khokhlova, Vera; Blanc-Benon, Philippe

    2010-12-01

    The propagation of nonlinear spherically diverging N-waves in homogeneous air is studied experimentally and theoretically. A spark source is used to generate high amplitude (1.4 kPa) short duration (40 μs) N-waves; acoustic measurements are performed using microphones (3 mm diameter, 150 kHz bandwidth). Numerical modeling with the generalized Burgers equation is used to reveal the relative effects of acoustic nonlinearity, thermoviscous absorption, and oxygen and nitrogen relaxation on the wave propagation. The results of modeling are in a good agreement with the measurements in respect to the wave amplitude and duration. However, the measured rise time of the front shock is ten times longer than the calculated one, which is attributed to the limited bandwidth of the microphone. To better resolve the shock thickness, a focused shadowgraphy technique is used. The recorded optical shadowgrams are compared with shadow patterns predicted by geometrical optics and scalar diffraction model of light propagation. It is shown that the geometrical optics approximation results in overestimation of the shock rise time, while the diffraction model allows to correctly resolve the shock width. A combination of microphone measurements and focused optical shadowgraphy is therefore a reliable way of studying evolution of spark-generated shock waves in air. PMID:21218866

  7. Strong acoustic wave action

    NASA Astrophysics Data System (ADS)

    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.

  8. Generation and Radiation of Acoustic Waves from a 2-D Shear Layer

    NASA Technical Reports Server (NTRS)

    Agarwal, Anurag; Morris, Philip J.

    2000-01-01

    A parallel numerical simulation of the radiation of sound from an acoustic source inside a 2-D jet is presented in this paper. This basic benchmark problem is used as a test case for scattering problems that are presently being solved by using the Impedance Mismatch Method (IMM). In this technique, a solid body in the domain is represented by setting the acoustic impedance of each medium, encountered by a wave, to a different value. This impedance discrepancy results in reflected and scattered waves with appropriate amplitudes. The great advantage of the use of this method is that no modifications to a simple Cartesian grid need to be made for complicated geometry bodies. Thus, high order finite difference schemes may be applied simply to all parts of the domain. In the IMM, the total perturbation field is split into incident and scattered fields. The incident pressure is assumed to be known and the equivalent sources for the scattered field are associated with the presence of the scattering body (through the impedance mismatch) and the propagation of the incident field through a non-uniform flow. An earlier version of the technique could only handle uniform flow in the vicinity of the source and at the outflow boundary. Scattering problems in non-uniform mean flow are of great practical importance (for example, scattering from a high lift device in a non-uniform mean flow or the effects of a fuselage boundary layer). The solution to this benchmark problem, which has an acoustic wave propagating through a non-uniform mean flow, serves as a test case for the extensions of the IMM technique.

  9. Stable Vortex Generation in Liquid Filled Wells by Mode Conversion of Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Landskron, Johannes; Schmidt, Katrin; Kufner, Maria; Lindner, Gerhard

    The formation of stable vortex flow pattern has been observed at liquid filled aluminum wells of 15 to 30 mm diameter when Lamb waves are excited on the bottom of the wells by piezoelectric transducers operated at a frequency of 1 MHz. The shape of the vortex pattern changed with the position of the transducer. Strong differences in mixing times were observed between water and ethanol when the filling level was changed and a remarkable reduction of mixing time was achieved by the addition of a small amount of detergent to water at small filling levels. Besides mixing of liquids thermal equilibration within a liquid volume was accelerated by acoustic streaming.

  10. Computation of the pressure field generated by surface acoustic waves in microchannels.

    PubMed

    Darinskii, A N; Weihnacht, M; Schmidt, H

    2016-07-01

    The high-frequency pressure induced by a surface acoustic wave in the fluid filling a microchannel is computed by solving the full scattering problem. The microchannel is fabricated inside a container attached to the top of a piezoelectric substrate where the surface wave propagates. The finite element method is used. The pressure found in this way is compared with the pressure obtained by solving boundary-value problems formulated on the basis of simplifications which have been introduced in earlier papers by other research studies. The considered example shows that the difference between the results can be significant, ranging from several tens of percent up to several times in different points inside the channel. PMID:27314212

  11. Quantum positron acoustic waves

    SciTech Connect

    Metref, Hassina; Tribeche, Mouloud

    2014-12-15

    Nonlinear quantum positron-acoustic (QPA) waves are investigated for the first time, within the theoretical framework of the quantum hydrodynamic model. In the small but finite amplitude limit, both deformed Korteweg-de Vries and generalized Korteweg-de Vries equations governing, respectively, the dynamics of QPA solitary waves and double-layers are derived. Moreover, a full finite amplitude analysis is undertaken, and a numerical integration of the obtained highly nonlinear equations is carried out. The results complement our previously published results on this problem.

  12. Simulation study and guidelines to generate Laser-induced Surface Acoustic Waves for human skin feature detection

    NASA Astrophysics Data System (ADS)

    Li, Tingting; Fu, Xing; Chen, Kun; Dorantes-Gonzalez, Dante J.; Li, Yanning; Wu, Sen; Hu, Xiaotang

    2015-12-01

    Despite the seriously increasing number of people contracting skin cancer every year, limited attention has been given to the investigation of human skin tissues. To this regard, Laser-induced Surface Acoustic Wave (LSAW) technology, with its accurate, non-invasive and rapid testing characteristics, has recently shown promising results in biological and biomedical tissues. In order to improve the measurement accuracy and efficiency of detecting important features in highly opaque and soft surfaces such as human skin, this paper identifies the most important parameters of a pulse laser source, as well as provides practical guidelines to recommended proper ranges to generate Surface Acoustic Waves (SAWs) for characterization purposes. Considering that melanoma is a serious type of skin cancer, we conducted a finite element simulation-based research on the generation and propagation of surface waves in human skin containing a melanoma-like feature, determine best pulse laser parameter ranges of variation, simulation mesh size and time step, working bandwidth, and minimal size of detectable melanoma.

  13. Microfluidic pumps employing surface acoustic waves generated in ZnO thin films

    SciTech Connect

    Du, X. Y.; Flewitt, A. J.; Milne, W. I.; Fu, Y. Q.; Luo, J. K.

    2009-01-15

    ZnO thin film based surface acoustic wave (SAW) devices have been utilized to fabricate microfluidic pumps. The SAW devices were fabricated on nanocrystalline ZnO piezoelectric thin films deposited on Si substrates using rf magnetron sputtering and use a Sezawa wave mode for effective droplet motion. The as-deposited ZnO surface is hydrophilic, with a water contact angle of {approx}75 deg., which prevents droplet pumping. Therefore, the ZnO surface was coated using a self-assembled monolayer of octadecyltrichlorosilane which forms a hydrophobic surface with a water contact angle of {approx}110 deg. Liquid droplets between 0.5 and 1 {mu}l in volume were successfully pumped on the hydrophobic ZnO surface at velocities up to 1 cm s{sup -1}. Under acoustic pressure, the water droplet on an hydrophilic surface becomes deformed, and the asymmetry in the contact angle at the trailing and leading edges allow the force acting upon the droplet to be calculated. These forces, which increase with input voltage above a threshold level, are found to be in the range of {approx}100 {mu}N. A pulsed rf signal has also been used to demonstrate precision manipulation of the liquid droplets. Furthermore, a SAW device structure is demonstrated in which the ZnO piezoelectric only exists under the input and output transducers. This structure still permits pumping, while avoiding direct contact between the piezoelectric material and the fluid. This is of particular importance for biological laboratory-on-a-chip applications.

  14. A secondary diffraction effect and the generation of Scholte-Stoneley acoustic wave on periodically corrugated surface

    NASA Astrophysics Data System (ADS)

    Liu, Jingfei; Declercq, Nico F.

    2016-05-01

    When a wideband sound beam is incident onto a periodically corrugated surface, a series of diffraction related phenomena can occur. In this work, we report the observation of a secondary diffraction, which is different from those previously investigated. The search of the physical origin of this newly observed diffraction leads to the discovery of the possibility of generating Scholte-Stoneley waves, inspired by Guo, Margetan, and Thompson's work in sound backscattering from rough surfaces, through a nonconventional energy conversion mechanism: direct coupling of the incident energy with the periodic interface. This mechanism allows for the Scholte-Stoneley wave generation at any angle of incidence, which distinguishes it from the well-known energy conversion mechanism of the diffraction-related phenomena such as acoustic Wood anomaly and backward displacement in which wave generation is highly angle dependent. The findings of this work not only enrich the understanding of the interaction of sound with periodically corrugated structures but also provide a new surface wave generation method for the potential applications in nondestructive evaluation of materials.

  15. Surface acoustic wave dust deposition monitor

    DOEpatents

    Fasching, G.E.; Smith, N.S. Jr.

    1988-02-12

    A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.

  16. Parameters effects study on pulse laser for the generation of surface acoustic waves in human skin detection applications

    NASA Astrophysics Data System (ADS)

    Li, Tingting; Fu, Xing; Dorantes-Gonzalez, Dante J.; Chen, Kun; Li, Yanning; Wu, Sen

    2015-10-01

    Laser-induced Surface Acoustic Waves (LSAWs) has been promisingly and widely used in recent years due to its rapid, high accuracy and non-contact evaluation potential of layered and thin film materials. For now, researchers have applied this technology on the characterization of materials' physical parameters, like Young's Modulus, density, and Poisson's ratio; or mechanical changes such as surface cracks and skin feature like a melanoma. While so far, little research has been done on providing practical guidelines on pulse laser parameters to best generate SAWs. In this paper finite element simulations of the thermos-elastic process based on human skin model for the generation of LSAWs were conducted to give the effects of pulse laser parameters have on the generated SAWs. And recommendations on the parameters to generate strong SAWs for detection and surface characterization without cause any damage to skin are given.

  17. Guided acoustic wave inspection system

    DOEpatents

    Chinn, Diane J.

    2004-10-05

    A system for inspecting a conduit for undesirable characteristics. A transducer system induces guided acoustic waves onto said conduit. The transducer system detects the undesirable characteristics of the conduit by receiving guided acoustic waves that contain information about the undesirable characteristics. The conduit has at least two sides and the transducer system utilizes flexural modes of propagation to provide inspection using access from only the one side of the conduit. Cracking is detected with pulse-echo testing using one transducer to both send and receive the guided acoustic waves. Thinning is detected in through-transmission testing where one transducer sends and another transducer receives the guided acoustic waves.

  18. Dust-Acoustic Waves: Visible Sound Waves

    SciTech Connect

    Merlino, Robert L.

    2009-11-10

    A historical overview of some of the early theoretical and experimental work on dust acoustic waves is given. The basic physics of the dust acoustic wave and some of the theoretical refinements that have been made, including the effects of collisions, plasma absorption, dust charge fluctuations, particle drifts and strong coupling effects are discussed. Some recent experimental findings and outstanding problems are also presented.

  19. Generation of Acoustic-Gravity Waves in Ionospheric HF Heating Experiments: Simulating Large-Scale Natural Heat Sources

    NASA Astrophysics Data System (ADS)

    Pradipta, Rezy

    In this thesis, we investigate the potential role played by large-scale anomalous heat sources (e.g. prolonged heat wave events) in generating acoustic-gravity waves (AGWs) that might trigger widespread plasma turbulence in the ionospheric layer. The main hypothesis is that, the thermal gradients associated with the heat wave fronts could act as a source of powerful AGW capable of triggering ionospheric plasma turbulence over extensive areas. In our investigations, first we are going to examine a case study of the summer 2006 North American heat wave event. Our examination of GPS-derived total electron content (TEC) data over the North American sector reveals a quite noticeable increase in the level of daily plasma density fluctuations during the summer 2006 heat wave period. Comparison with the summer 2005 and summer 2007 data further confirms that the observed increase of traveling ionospheric disturbances (TIDs) during the summer 2006 heat wave period was not simply a regular seasonal phenomenon. Furthermore, a series of field experiments had been carried out at the High-frequency Active Auroral Research Program (HAARP) facility in order to physically simulate the process of AGW/TID generation by large-scale thermal gradients in the ionosphere. In these ionospheric HF heating experiments, we create some time-varying artificial thermal gradients at an altitude of 200--300 km above the Earth's surface using vertically-transmitted amplitude-modulated 0-mode HF heater waves. For our experiments, a number of radio diagnostic instruments had been utilized to detect the characteristic signatures of heater-generated AGW/TID. So far, we have been able to obtain several affirmative indications that some artificial AGW/TID are indeed being radiated out from the heated plasma volume during the HAARP-AGW experiments. Based on the experimental evidence, we may conclude that it is certainly quite plausible for large-scale thermal gradients associated with severe heat wave

  20. On the detection of acoustic-gravity waves generated by typhoon by use of real time HF Doppler frequency shift sounding system

    NASA Astrophysics Data System (ADS)

    Huang, Yinn-Nien; Cheng, Kang; Chen, Sen-Wen

    1985-07-01

    A development of a direct vision type high-frequency Doppler frequency sounder and a setup of HF Doppler frequency sounding array at the northern part of Taiwan Island were presented. By use of all typhoons that occurred in 1982 and 1983, the detectability of the typhoon-generated acoustic-gravity waves by use of this HF Doppler frequency sounding array was presented. The results show that the acoustic-gravity waves generated by a typhoon can be detected by this sounding array; however, the detectability is only 2 out of 12.

  1. Discussion about generation mechanisms of third-order nonlinear signals in surface acoustic wave resonators based on simulation

    NASA Astrophysics Data System (ADS)

    Nakagawa, Ryo; Suzuki, Takanao; Shimizu, Hiroshi; Kyoya, Haruki; Nako, Katsuhiro; Hashimoto, Ken-ya

    2016-07-01

    In this paper, we discuss the generation mechanisms of third-order nonlinearity in surface acoustic wave (SAW) devices on the basis of simulation results, which are obtained by a proposed method for this discussion. First, eight nonlinear terms are introduced to the piezoelectric constitutive equations, and nonlinear stress and electric flux fields are estimated using linear strain and electric fields calculated by a linear analysis, i.e., the coupling of mode simulation. Then, their contributions are embedded as voltage and current sources, respectively, in an equivalent circuit model, and nonlinear signals appearing at external ports are estimated. It is shown that eight coefficients of the nonlinear terms can be determined from a series of experiments carried out at various driving and resulting frequencies. This is because the effect of each nonlinear term on the nonlinear signal outputs changes markedly with the conditions. When the coefficients are determined properly, the simulations agree well with some measurement results under various conditions.

  2. Surface acoustic wave microfluidics

    PubMed Central

    Ding, Xiaoyun; Li, Peng; Lin, Sz-Chin Steven; Stratton, Zackary S.; Nama, Nitesh; Guo, Feng; Slotcavage, Daniel; Mao, Xiaole; Shi, Jinjie; Costanzo, Francesco; Huang, Tony Jun

    2014-01-01

    The recent introduction of surface acoustic wave (SAW) technology onto lab-on-a-chip platforms has opened a new frontier in microfluidics. The advantages provided by such SAW microfluidics are numerous: simple fabrication, high biocompatibility, fast fluid actuation, versatility, compact and inexpensive devices and accessories, contact-free particle manipulation, and compatibility with other microfluidic components. We believe that these advantages enable SAW microfluidics to play a significant role in a variety of applications in biology, chemistry, engineering, and medicine. In this review article, we discuss the theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended. We then review the SAW-enabled microfluidic devices demonstrated to date, starting with devices that accomplish fluid mixing and transport through the use of travelling SAW; we follow that by reviewing the more recent innovations achieved with standing SAW that enable such actions as particle/cell focusing, sorting, and patterning. Finally, we look forward and appraise where the discipline of SAW microfluidics could go next. PMID:23900527

  3. Experimental and analytical investigation of acoustic streaming generated by standing ultrasonic waves in an open boundaries

    NASA Astrophysics Data System (ADS)

    Kwon, K.; Loh, B.-G.; Lee, D.-R.

    2007-12-01

    Acoustic streaming patterns, velocity fields, which is induced by a cylindrical ultrasonic exciter vibrating at 28.4kHz in an open physical boundaries, is analytically and experimentally investigated using Particle Imaging Velocimetry (PIV). Induced acoustic streaming patterns and velocity fields for the gaps of 18mm at which the irrotational tangential velocity becomes a maximum, resulting in a substantial increase in the acoustic streaming velocity and pronounced visualization of streaming patterns between the vibrator and quiescent glass plate are presented. The overall air flow patterns at the gaps of 24, 30, 36mm are similar to the gap of 18 mm but as the gap increases the frequency of occurrence and irregularity of vortices in the gap appear to increase. The symmetric definite steady circular flow with local vortices is observed. The maximum streaming velocity measured stands at 0.16 cm/s with a vibration amplitude of 50 micrometers. Theoretical analysis indicates that the pattern of air flow in the gap is determined by the top and bottom limiting velocities induced by acoustic streaming within the Stokes boundary layer and that the streaming pattern is symmetrical with respect to the center axis of the vibrator by reason of symmetry. The comparison between the experimental data and the theoretical estimation based on Nyborg and Jackson is performed.

  4. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Shen, Jian Qi

    2016-08-01

    In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.

  5. Swimming using surface acoustic waves.

    PubMed

    Bourquin, Yannyk; Cooper, Jonathan M

    2013-01-01

    Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel. PMID:23431358

  6. Swimming Using Surface Acoustic Waves

    PubMed Central

    Bourquin, Yannyk; Cooper, Jonathan M.

    2013-01-01

    Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel. PMID:23431358

  7. Active micromixer using surface acoustic wave streaming

    DOEpatents

    Branch; Darren W. , Meyer; Grant D. , Craighead; Harold G.

    2011-05-17

    An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

  8. Acoustic and gravity waves in the neutral atmosphere and the ionosphere, generated by severe storms

    NASA Technical Reports Server (NTRS)

    Balachandran, N. K.

    1983-01-01

    Gravity waves in the neutral atmosphere and their propagation in the ionosphere and the study of infrasonic signals from thunder were investigated. Doppler shifts of the order of 0.1 Hz are determined and they provide high-resolution measurements of the movements in the ionosphere. By using an array of transmitters with different frequencies and at different locations, the horizontal and vertical propagation vectors of disturbances propagating through the ionosphere are determined.

  9. Transverse mechanical properties of cell walls of single living plant cells probed by laser-generated acoustic waves.

    PubMed

    Gadalla, Atef; Dehoux, Thomas; Audoin, Bertrand

    2014-05-01

    Probing the mechanical properties of plant cell wall is crucial to understand tissue dynamics. However, the exact symmetry of the mechanical properties of this anisotropic fiber-reinforced composite remains uncertain. For this reason, biologically relevant measurements of the stiffness coefficients on individual living cells are a challenge. For this purpose, we have developed the single-cell optoacoustic nanoprobe (SCOPE) technique, which uses laser-generated acoustic waves to probe the stiffness, thickness and viscosity of live single-cell subcompartments. This all-optical technique offers a sub-micrometer lateral resolution, nanometer in-depth resolution, and allows the non-contact measurement of the mechanical properties of live turgid tissues without any assumption of mechanical symmetry. SCOPE experiments reveal that single-cell wall transverse stiffness in the direction perpendicular to the epidermis layer of onion cells is close to that of cellulose. This observation demonstrates that cellulose microfibrils are the main load-bearing structure in this direction, and suggests strong bonding of microfibrils by hemicelluloses. Altogether our measurement of the viscosity at high frequencies suggests that the rheology of the wall is dominated by glass-like dynamics. From a comparison with literature, we attribute this behavior to the influence of the pectin matrix. SCOPE's ability to unravel cell rheology and cell anisotropy defines a new class of experiments to enlighten cell nano-mechanics. PMID:24615232

  10. Imaging of Acoustic Waves in Sand

    SciTech Connect

    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.

  11. A simplified physical model of pressure wave dynamics and acoustic wave generation induced by laser absorption in the retina.

    PubMed

    Till, S J; Milsom, P K; Rowlands, G

    2004-07-01

    Shock waves have been proposed in the literature as a mechanism for retinal damage induced by ultra-short laser pulses. For a spherical absorber, we derive a set of linear equations describing the propagation of pressure waves. We show that the formation of shock fronts is due to the form of the absorber rather than the inclusion of nonlinear terms in the equations. The analytical technique used avoids the need for a Laplace transform approach and is easily applied to other absorber profiles. Our analysis suggests that the 'soft' nature of the membrane surrounding retinal melanosomes precludes shock waves as a mechanism for the retinal damage induced by ultra-short pulse lasers. The quantitative estimates of the pressure gradients induced by laser absorption which are made possible by this work, together with detailed meso-scale or molecular modelling, will allow alternative damage mechanisms to be identified. PMID:15210319

  12. On the Synchronization of Acoustic Gravity Waves

    NASA Astrophysics Data System (ADS)

    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.

  13. Multi-reflective acoustic wave device

    DOEpatents

    Andle, Jeffrey C.

    2006-02-21

    An acoustic wave device, which utilizes multiple localized reflections of acoustic wave for achieving an infinite impulse response while maintaining high tolerance for dampening effects, is disclosed. The device utilized a plurality of electromechanically significant electrodes disposed on most of the active surface. A plurality of sensors utilizing the disclosed acoustic wave mode device are also described.

  14. Producing undistorted acoustic sine waves.

    PubMed

    Boutin, Henri; Smith, John; Wolfe, Joe

    2014-04-01

    A simple digital method is described that can produce an undistorted acoustic sine wave using an amplifier and loudspeaker having considerable intrinsic distortion, a common situation at low frequencies and high power. The method involves, first, using a pure sine wave as the input and measuring the distortion products. An iterative procedure then progressively adds harmonics with appropriate amplitude and phase to cancel any distortion products. The method is illustrated by producing a pure 52 Hz sine wave at 107 dB sound pressure level with harmonic distortion reduced over the audible range to >65 dB below the fundamental. PMID:25234964

  15. Acoustic-gravity waves, theory and application

    NASA Astrophysics Data System (ADS)

    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.

  16. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    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.

  17. Marble Ageing Characterization by Acoustic Waves

    NASA Astrophysics Data System (ADS)

    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

  18. Surface acoustic wave oxygen sensor

    NASA Technical Reports Server (NTRS)

    Collman, James P.; Oglesby, Donald M.; Upchurch, Billy T.; Leighty, Bradley D.; Zhang, Xumu; Herrmann, Paul C.

    1994-01-01

    A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.

  19. Nonlinear positron acoustic solitary waves

    SciTech Connect

    Tribeche, Mouloud; Aoutou, Kamel; Younsi, Smain; Amour, Rabia

    2009-07-15

    The problem of nonlinear positron acoustic solitary waves involving the dynamics of mobile cold positrons is addressed. A theoretical work is presented to show their existence and possible realization in a simple four-component plasma model. The results should be useful for the understanding of the localized structures that may occur in space and laboratory plasmas as new sources of cold positrons are now well developed.

  20. Acoustic Waves in Medical Imaging and Diagnostics

    PubMed Central

    Sarvazyan, Armen P.; Urban, Matthew W.; Greenleaf, James F.

    2013-01-01

    Up until about two decades ago acoustic imaging and ultrasound imaging were synonymous. The term “ultrasonography,” or its abbreviated version “sonography” meant an imaging modality based on the use of ultrasonic compressional bulk waves. Since the 1990s numerous acoustic imaging modalities started to emerge based on the use of a different mode of acoustic wave: shear waves. It was demonstrated that imaging with these waves can provide very useful and very different information about the biological tissue being examined. We will discuss physical basis for the differences between these two basic modes of acoustic waves used in medical imaging and analyze the advantages associated with shear acoustic imaging. A comprehensive analysis of the range of acoustic wavelengths, velocities, and frequencies that have been used in different imaging applications will be presented. We will discuss the potential for future shear wave imaging applications. PMID:23643056

  1. Reflection properties of gravito-acoustic waves

    NASA Astrophysics Data System (ADS)

    Jovanović, Gordana

    2016-03-01

    We derive the dispersion equation for gravito-acoustic waves in an isothermal gravitationally stratified nonmagnetized atmosphere. In this model, with constant sound speed, it is possible to derive analytically the equations for gravito-acoustic waves. The large value of the viscous Reynolds number in the solar atmosphere imply that the dissipative terms in HD (hydrodynamics) equations are negligible. We consider the plane boundary z = 0 between two isothermal atmosphere regions and using the boundary conditions we derive the equation for the reflection coeffcient of gravito-acoustic waves. For the frequencies much greater than acoustic cutoff frequency, the reflection coefficient of the acoustic waves modified by gravity is the same as in the case of the pure acoustic waves. Reflection coefficient for the gravity waves is very high, R ≈ 1.

  2. Acoustic Remote Sensing of Rogue Waves

    NASA Astrophysics Data System (ADS)

    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.

  3. Dual output acoustic wave sensor for molecular identification

    SciTech Connect

    Frye, G.C.; Martin, S.J.

    1990-10-03

    The invention comprises a method for the identification and quantification of sorbed chemical species onto a coating of a device capable of generating and receiving an acoustic wave, by measuring the changes in the velocity of the acoustic wave resulting from the sorption of the chemical species into the coating as the wave travels through the coating and by measuring the changes in the attenuation of an acoustic wave resulting from the sorption of the chemical species into the coating as the wave travels through the coating. The inventive method further correlates the magnitudes of the changes of velocity with respect to changes of the attenuation of the acoustic wave to identify the sorbed chemical species. The absolute magnitudes of the velocity changes or the absolute magnitude of the attenuation changes are used to determine the concentration of the identified chemical species.

  4. Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms

    NASA Astrophysics Data System (ADS)

    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.

  5. Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms

    SciTech Connect

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

    2015-07-30

    Acoustic waves with periods of 2–4 min and gravity waves with periods of 6–16 min have been detected at ionospheric heights (25–350 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Air-coupled acoustic radiation force for non-contact generation of broadband mechanical waves in soft media

    NASA Astrophysics Data System (ADS)

    Ambroziński, Łukasz; Pelivanov, Ivan; Song, Shaozhen; Yoon, Soon Joon; Li, David; Gao, Liang; Shen, Tueng T.; Wang, Ruikang K.; O'Donnell, Matthew

    2016-07-01

    A non-contact method for efficient, non-invasive excitation of mechanical waves in soft media is proposed, in which we focus an ultrasound (US) signal through air onto the surface of a medium under study. The US wave reflected from the air/medium interface provides radiation force to the medium surface that launches a transient mechanical wave in the transverse (lateral) direction. The type of mechanical wave is determined by boundary conditions. To prove this concept, a home-made 1 MHz piezo-ceramic transducer with a matching layer to air sends a chirped US signal centered at 1 MHz to a 1.6 mm thick gelatin phantom mimicking soft biological tissue. A phase-sensitive (PhS)-optical coherence tomography system is used to track/image the mechanical wave. The reconstructed transient displacement of the mechanical wave in space and time demonstrates highly efficient generation, thus offering great promise for non-contact, non-invasive characterization of soft media, in general, and for elasticity measurements in delicate soft tissues and organs in bio-medicine, in particular.

  8. Isomorphic surface acoustic waves on multilayer structures

    NASA Astrophysics Data System (ADS)

    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 <110>-propagating GaAs for which a fair amount of slowness surface data exists. Finally, using angular spectrum of plane waves diffraction theory, we present data which substantiate the claim that self-collimating can more accurately be viewed as isomorphic because the SAW beam profile can propagate without changing its shape.

  9. Robust acoustic wave manipulation of bubbly liquids

    NASA Astrophysics Data System (ADS)

    Gumerov, N. A.; Akhatov, I. S.; Ohl, C.-D.; Sametov, S. P.; Khazimullin, M. V.; Gonzalez-Avila, S. R.

    2016-03-01

    Experiments with water-air bubbly liquids when exposed to acoustic fields of frequency ˜100 kHz and intensity below the cavitation threshold demonstrate that bubbles ˜30 μm in diameter can be "pushed" away from acoustic sources by acoustic radiation independently from the direction of gravity. This manifests formation and propagation of acoustically induced transparency waves (waves of the bubble volume fraction). In fact, this is a collective effect of bubbles, which can be described by a mathematical model of bubble self-organization in acoustic fields that matches well with our experiments.

  10. Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms

    DOE PAGESBeta

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

    2015-07-30

    Acoustic waves with periods of 2–4 min and gravity waves with periods of 6–16 min have been detected at ionospheric heights (25–350 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 wavemore » disturbed area and amplitude scale with thunderstorm activity, with even small storms (i.e., individual storm cells) producing an increase of gravity waves.« less

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

    SciTech Connect

    Vu, Cung Khac; Sinha, Dipen N; Pantea, Cristian; Nihei, Kurt T; Schmitt, Denis P; Skelt, Christopher

    2013-10-01

    In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency and the second frequency; and transmitting the collimated beam through a diverging acoustic lens to compensate for a refractive effect caused by the curvature of the borehole.

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

    NASA Astrophysics Data System (ADS)

    Andreev, Pavel A.; Kuz'menkov, L. S.

    2016-05-01

    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 spin-electron acoustic waves.

  14. Acoustic wave coupled magnetoelectric effect

    NASA Astrophysics Data System (ADS)

    Gao, J. S.; Zhang, N.

    2016-07-01

    Magnetoelectric (ME) coupling by acoustic waveguide was developed. Longitudinal and transversal ME effects of larger than 44 and 6 (V cm-1 Oe-1) were obtained with the waveguide-coupled ME device, respectively. Several resonant points were observed in the range of frequency lower than 47 kHz. Analysis showed that the standing waves in the waveguide were responsible for those resonances. The frequency and size dependence of the ME effects were investigated. A resonant condition about the geometrical size of the waveguide was obtained. Theory and experiments showed the resonant frequencies were closely influenced by the diameter and length of the waveguide. A series of double-peak curves of longitudinal magnetoelectric response were obtained, and their significance was discussed initially.

  15. Surface acoustic wave stabilized oscillators

    NASA Technical Reports Server (NTRS)

    Parker, T. E.

    1978-01-01

    A number of 401.2 MHz surface acoustic wave (SAW) controlled oscillators were built and tested. The performance of these oscillators was evaluated for possible use as stable oscillators in communication systems. A short term frequency stability of better than 1 x 10 to the minus 9th power for one second was measured for the SAW oscillators. Long term frequency drift was measured and was found to be dependent on SAW design and packaging. Drift rates ranging from 15 ppm in twenty weeks to 2.5 ppm in twenty weeks were observed. Some further improvement was required. The temperature dependence of the saw oscillators was evaluated and it was concluded that some form of temperature compensation will be necessary to meet the requirements of some communication systems.

  16. Surface acoustic wave stabilized oscillators

    NASA Technical Reports Server (NTRS)

    Parker, T. E.; Lee, D. L.; Leja, I.

    1979-01-01

    Four areas of surface acoustic wave (SAW) controlled oscillators were investigated and a number of 401.2 MHz oscillators were constructed that showed improved performance. Aging studies on SAW devices packaged in HC36/U cold weld enclosures produced frequency drifts as low as 0.4 ppm in 35 weeks and drift rates well under 0.5 ppm/year. Temperature compensation circuits have substantially improved oscillator temperature stability, with a deviation of + or - 4 ppm observed over the range -45 C to + 40 C. High efficiency amplifiers were constructed for SAW oscillators and a dc to RF efficiency of 44 percent was obtained for an RF output of 25 mW. Shock and vibration tests were made on four oscillators and all survived 500 G shock pulses unchanged. Only when white noise vibration (20 Hz to 2000 Hz) levels of 20 G's rms were applied did some of the devices fail.

  17. An automated code generator for three-dimensional acoustic wave propagation with geometrically complex solid-wall boundaries

    NASA Astrophysics Data System (ADS)

    Dyson, Rodger William, Jr.

    1999-10-01

    Finding the sources of noise generation in a turbofan propulsion system requires a computational tool that has sufficient fidelity to simulate steep gradients in the flow field and sufficient efficiency to run on today's computer systems. The goal of this dissertation was to develop an automated code generator for the creation of software that numerically solves the linearized Euler equations on Cartesian grids in three dimensional spatial domains containing bodies with complex shapes. It is based upon the recently developed Modified Expansion Solution Approximation (MESA) series of explicit finite-difference schemes that provide spectral-like resolution with extraordinary efficiency. The accuracy of these methods can, in theory, be arbritarily high in both space and time, without the significant inefficiences of Runge- Kutta based schemes. The complexity of coding these schemes was, however, very high, resulting in code that could not compile or took so long to write in FORTRAN that they were rendered impractical. Therefore, a tool in Mathematica was developed that could automatically code the MESA schemes into FORTRAN and the MESA schemes themselves were reformulated into a very simple form-making them practical to use without automation or very powerful with it. A method for automatically creating the MESA propagation schemes and their FORTRAN code in two and three spatial dimensions is shown with up to 29th order accuracy in space and time. Also, a method for treating solid wall boundaries in two dimensions is shown with up to 11th order accuracy on grid aligned boundaries and with up to 2nd order accuracy on generalized boundaries. Finally, an automated method for parallelizing these approaches on large scale parallel computers with near perfect scalability is presented. All these methods are combined to form a turnkey code generation tool in Mathematica that once provided the CAD geometry file can automatically simulate the acoustical physics by replacing the

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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 canceled). The presented ideas open a way towards the control of acoustic wave propagation in nonlinear regime. xml:lang="fr"

  19. Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Chirstopher

    2013-10-15

    In some aspects of the invention, a method of generating a beam of acoustic energy in a borehole is disclosed. The method includes generating a first acoustic wave at a first frequency; generating a second acoustic wave at a second frequency different than the first frequency, wherein the first acoustic wave and second acoustic wave are generated by at least one transducer carried by a tool located within the borehole; transmitting the first and the second acoustic waves into an acoustically non-linear medium, wherein the composition of the non-linear medium produces a collimated beam by a non-linear mixing of the first and second acoustic waves, wherein the collimated beam has a frequency based upon a difference between the first frequency range and the second frequency, and wherein the non-linear medium has a velocity of sound between 100 m/s and 800 m/s.

  20. Chromospheric heating by acoustic shock waves

    NASA Technical Reports Server (NTRS)

    Jordan, Stuart D.

    1993-01-01

    Work by Anderson & Athay (1989) suggests that the mechanical energy required to heat the quiet solar chromosphere might be due to the dissipation of weak acoustic shocks. The calculations reported here demonstrate that a simple picture of chromospheric shock heating by acoustic waves propagating upward through a model solar atmosphere, free of both magnetic fields and local inhomogeneities, cannot reproduce their chromospheric model. The primary reason is the tendency for vertically propagating acoustic waves in the range of allowed periods to dissipate too low in the atmosphere, providing insufficient residual energy for the middle chromosphere. The effect of diverging magnetic fields and the corresponding expanding acoustic wavefronts on the mechanical dissipation length is then discussed as a means of preserving a quasi-acoustic heating hypothesis. It is argued that this effect, in a canopy that overlies the low chromosphere, might preserve the acoustic shock hypothesis consistent with the chromospheric radiation losses computed by Anderson & Athay.

  1. A New Wave of Acoustics.

    ERIC Educational Resources Information Center

    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)

  2. Microfabricated bulk wave acoustic bandgap device

    DOEpatents

    Olsson, Roy H.; El-Kady, Ihab F.; McCormick, Frederick; Fleming, James G.; Fleming, Carol

    2010-06-08

    A microfabricated bulk wave acoustic bandgap device comprises a periodic two-dimensional array of scatterers embedded within the matrix material membrane, wherein the scatterer material has a density and/or elastic constant that is different than the matrix material and wherein the periodicity of the array causes destructive interference of the acoustic wave within an acoustic bandgap. The membrane can be suspended above a substrate by an air or vacuum gap to provide acoustic isolation from the substrate. The device can be fabricated using microelectromechanical systems (MEMS) technologies. Such microfabricated bulk wave phononic bandgap devices are useful for acoustic isolation in the ultrasonic, VHF, or UHF regime (i.e., frequencies of order 1 MHz to 10 GHz and higher, and lattice constants of order 100 .mu.m or less).

  3. Microfabricated bulk wave acoustic bandgap device

    DOEpatents

    Olsson, Roy H.; El-Kady, Ihab F.; McCormick, Frederick; Fleming, James G.; Fleming, legal representative, Carol

    2010-11-23

    A microfabricated bulk wave acoustic bandgap device comprises a periodic two-dimensional array of scatterers embedded within the matrix material membrane, wherein the scatterer material has a density and/or elastic constant that is different than the matrix material and wherein the periodicity of the array causes destructive interference of the acoustic wave within an acoustic bandgap. The membrane can be suspended above a substrate by an air or vacuum gap to provide acoustic isolation from the substrate. The device can be fabricated using microelectromechanical systems (MEMS) technologies. Such microfabricated bulk wave phononic bandgap devices are useful for acoustic isolation in the ultrasonic, VHF, or UHF regime (i.e., frequencies of order 1 MHz to 10 GHz and higher, and lattice constants of order 100 .mu.m or less).

  4. A simulation study of the convective instability and subsequent generation of Acoustic-gravity waves in the troposphere to MLT region

    NASA Astrophysics Data System (ADS)

    Tiwari, B. R.; Kherani, E. A.; Sobral, J. H. A.

    2014-12-01

    The convective instability (CI) is excited in the troposphere in the presence of negative temperature gradient. The rising bubbles generated by the instability act like pressure disturbances at the top of the troposphere and subsequently excite the acoustic-gravity waves (AGWs) in the atmosphere. These AGWs propagate radially outward towards overlying MLT region while their amplitude increases exponentially with increasing altitude. In the MLT region, these waves encounter thermal and density ducts, leading to the dissipation of these waves and subsequent generation of secondary AGWs. In this work, we present the simulation study of coupled convective instability - AGWs dynamics in the atmosphere covering troposphere to MLT region. We derive the governing hydrodynamics equations for the CI and AGWs that include the non-adiabatic dynamics of CI in the troposphere and compressible and ducting dynamics of AGWs above troposphere. These equations are solved using Finite-Time-Centered-Space difference method complemented by the Crank-Nicolson implicit scheme for the integration and Gradient-Conjugate method to solve the matrix equation. The simulation domain consists of altitude-longitude-latitude covering the tropical Brazilian region. The novel features of the present study are as follows: (1) Owing to the non-adiabatic dynamics, the CI in the troposphere grows for the adiabatically stable temperature profile (2) The growth remains linear and excite the bubbles reaching up to the base of the tropopause (~10 km altitude), (3) Thereafter, AGWs are excited attaining large amplitude in the MLT region, (4) In the MLT region, these large amplitude waves become ducted and as a result, the AGWs with short period equals to the Brunt-Vaisala period of MLT region, are amplified, (5) These ducting dynamics excite the atmospheric disturbances consist of ripples and bands, respectively associated with the short and long period AGWs.

  5. Detection of Acoustic/Infrasonic/Seismic Waves Generated by Hypersonic Re-Entry of the HAYABUSA Capsule and Fragmented Parts of the Spacecraft

    NASA Astrophysics Data System (ADS)

    Yamamoto, Masa-Yuki; Ishihara, Yoshiaki; Hiramatsu, Yoshihiro; Kitamura, Kazuki; Ueda, Masayoshi; Shiba, Yasuo; Furumoto, Muneyoshi; Fujita, Kazuhisa

    2011-10-01

    Acoustic/infrasonic/seismic waves were observed during the re-entry of the Japanese asteroid explorer ``HAYABUSA'' at 6 ground sites in Woomera, Australia, on 2010 June 13. Overpressure values of infrasound waves were detected at 3 ground sites in a range from 1.3 Pa, 1.0 Pa, and 0.7 Pa with each distance of 36.9 km, 54.9 km, and 67.8 km, respectively, apart from the SRC trajectory. Seismic waveforms through air-to-ground coupling processes were also detected at 6 sites, showing a one-to-one correspondence to infrasound waves at all simultaneous observation sites. Audible sound up to 1 kHz was recorded at one site with a distance of 67.8 km. The mother spacecraft was fragmented from 75 km down to 38 km with a few explosive enhancements of emissions. A persistent train of HAYABUSA re-entry was confirmed at an altitude range of between 92 km down to 82 km for about 3 minutes. Light curves of 136 fragmented parts of the spacecraft were analyzed in detail based on video observations taken at multiple ground sites, being classified into three types of fragmentations, i.e., melting, explosive, and re-fragmented types. In a comparison between infrasonic waves and video-image analyses, regarding the generation of sonic-boom type shock waves by hypersonically moving artificial meteors, both the sample return capsule and fragmented parts of the mother spacecraft, at an altitude of 40 ± 1 km were confirmed with a one-to-one correspondence with each other.

  6. Ion acoustic waves and related plasma observations in the solar wind

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Marsch, E.; Pilipp, W.; Schwenn, R.; Rosenbauer, H.

    1979-01-01

    The paper presents a study of the relationship between the interplanetary ion acoustic waves detected by Helios and the macroscopic and microscopic characteristics of the solar wind plasma. Two major mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. The results provide support to both mechanisms for generating the solar wind ion acoustic waves, although each mechanism has problems under certain conditions.

  7. Separation of acoustic waves in isentropic flow perturbations

    SciTech Connect

    Henke, Christian

    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.

  8. Writing magnetic patterns with surface acoustic waves

    SciTech Connect

    Li, Weiyang; Buford, Benjamin; Jander, Albrecht; Dhagat, Pallavi

    2014-05-07

    A novel patterning technique that creates magnetization patterns in a continuous magnetostrictive film with surface acoustic waves is demonstrated. Patterns of 10 μm wide stripes of alternating magnetization and a 3 μm dot of reversed magnetization are written using standing and focusing acoustic waves, respectively. The magnetization pattern is size-tunable, erasable, and rewritable by changing the magnetic field and acoustic power. This versatility, along with its solid-state implementation (no moving parts) and electronic control, renders it as a promising technique for application in magnetic recording, magnonic signal processing, magnetic particle manipulation, and spatial magneto-optical modulation.

  9. CONTROL OF LASER RADIATION PARAMETERS. GENERATION OF ULTRASHORT PULSES: Analysis of mode locking in a laser with a traveling-acoustic-wave modulator

    NASA Astrophysics Data System (ADS)

    Veselovskaya, T. V.; Klochan, E. L.; Lariontsev, E. G.

    1990-12-01

    A theoretical analysis is made of active mode locking in a solid-state laser with an acoustooptic modulator based on traveling acoustic waves. It is postulated that the acoustooptic modulator is placed in a V-shaped resonator so that diffraction feedback is established in the modulator. It is found that the transmission coefficient of the acoustooptic modulator is a function of time. The mode locking achieved in a V-shaped resonator is equivalent to that observed in lasers with intracavity frequency modulation of the radiation. An investigation is made of the stability of mode locking in a resonator with a traveling-acoustic-wave acoustooptic modulator.

  10. Tunable damper for an acoustic wave guide

    SciTech Connect

    Rogers, S.C.

    1984-06-05

    A damper for tunably damping acoustic waves in an ultrasonic waveguide is provided which may be used in a hostile environment such as a nuclear reactor. The area of the waveguide, which may be a selected size metal rod in which acoustic waves are to be damped, is wrapped, or surrounded, by a mass of stainless steel wool. The wool wrapped portion is then sandwiched between tuning plates, which may also be stainless steel, by means of clamping screws which may be adjusted to change the clamping force of the sandwiched assembly along the waveguide section. The plates are preformed along their length in a sinusoidally bent pattern with a period approximately equal to the acoustic wavelength which is to be damped. The bent pattern of the opposing plates are in phase along their length relative to their sinusoidal patterns so that as the clamping screws are tightened a bending stress is applied to the waveguide at 180/sup 0/ intervals along the damping section to oppose the acoustic wave motions in the waveguide and provide good coupling of the wool to the guide. The damper is tuned by selectively tightening the clamping screws while monitoring the amplitude of the acoustic waves launched in the waveguide. It may be selectively tuned to damp particular acoustic wave modes (torsional or extensional, for example) and/or frequencies while allowing others to pass unattenuated.

  11. Tunable damper for an acoustic wave guide

    DOEpatents

    Rogers, Samuel C.

    1984-01-01

    A damper for tunably damping acoustic waves in an ultrasonic waveguide is provided which may be used in a hostile environment such as a nuclear reactor. The area of the waveguide, which may be a selected size metal rod in which acoustic waves are to be damped, is wrapped, or surrounded, by a mass of stainless steel wool. The wool wrapped portion is then sandwiched between tuning plates, which may also be stainless steel, by means of clamping screws which may be adjusted to change the clamping force of the sandwiched assembly along the waveguide section. The plates are preformed along their length in a sinusoidally bent pattern with a period approximately equal to the acoustic wavelength which is to be damped. The bent pattern of the opposing plates are in phase along their length relative to their sinusoidal patterns so that as the clamping screws are tightened a bending stress is applied to the waveguide at 180.degree. intervals along the damping section to oppose the acoustic wave motions in the waveguide and provide good coupling of the wool to the guide. The damper is tuned by selectively tightening the clamping screws while monitoring the amplitude of the acoustic waves launched in the waveguide. It may be selectively tuned to damp particular acoustic wave modes (torsional or extensional, for example) and/or frequencies while allowing others to pass unattenuated.

  12. Tunable damper for an acoustic wave guide

    DOEpatents

    Rogers, S.C.

    1982-10-21

    A damper for tunably damping acoustic waves in an ultrasonic waveguide is provided which may be used in a hostile environment such as a nuclear reactor. The area of the waveguide, which may be a selected size metal rod in which acoustic waves are to be damped, is wrapped, or surrounded, by a mass of stainless steel wool. The wool wrapped portion is then sandwiched between tuning plates, which may also be stainless steel, by means of clamping screws which may be adjusted to change the clamping force of the sandwiched assembly along the waveguide section. The plates are preformed along their length in a sinusoidally bent pattern with a period approximately equal to the acoustic wavelength which is to be damped. The bent pattern of the opposing plates are in phase along their length relative to their sinusoidal patterns so that as the clamping screws are tightened a bending stress is applied to the waveguide at 180/sup 0/ intervals along the damping section to oppose the acoustic wave motions in the waveguide and provide good coupling of the wool to the guide. The damper is tuned by selectively tightening the clamping screws while monitoring the amplitude of the acoustic waves launched in the waveguide. It may be selectively tuned to damp particular acoustic wave modes (torsional or extensional, for example) and/or frequencies while allowing others to pass unattenuated.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Nonlinear scattering of acoustic waves by vibrating obstacles

    NASA Astrophysics Data System (ADS)

    Piquette, J. C.

    1983-06-01

    The problem of the generation of sum- and difference-frequency waves produced via the scattering of an acoustic wave by an obstacle whose surface vibrates harmonically was studied both theoretically and experimentally. The theoretical approach involved solving the nonlinear wave equation, subject to appropriate boundary conditions, by the use of a perturbation expansion of the fields and a Green's function method. In addition to ordinary rigid-body scattering, Censor predicted nongrowing waves at frequencies equal to the sum and to the difference of the frequencies of the primary waves. The solution to the nonlinear wave equation also yields scattered waves at the sum and difference frequencies. However, the nonlinearity of the medium causes these waves to grow with increasing distance from the scatter's surface and, after a very small distance, dominate those predicted by Censor. The simple-source formulation of the second-order nonlinear wave equation for a lossless fluid medium has been derived for arbitrary primary wave fields. This equation was used to solve the problem of nonlinear scattering of acoustic waves by a vibrating obstacle for three geometries: (1) a plane-wave scattering by a vibrating plane, (2) cylindrical-wave scattering by a vibrating cylinder, and (3) plane-wave scattering by a vibrating cylinder. Successful experimental validation of the theory was inhibited by previously unexpected levels of nonlinearity in the hydrophones used. Such high levels of hydrophone nonlinearity appeared in hydrophones that, by their geometry of construction, were expected to be fairly linear.

  15. INTERFERENCE FRINGES OF SOLAR ACOUSTIC WAVES AROUND SUNSPOTS

    SciTech Connect

    Chou, Dean-Yi; Zhao Hui; Yang, Ming-Hsu; Liang, Zhi-Chao

    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.

  16. Ion Acoustic Waves in Ultracold Neutral Plasmas

    SciTech Connect

    Castro, J.; McQuillen, P.; Killian, T. C.

    2010-08-06

    We photoionize laser-cooled atoms with a laser beam possessing spatially periodic intensity modulations to create ultracold neutral plasmas with controlled density perturbations. Laser-induced fluorescence imaging reveals that the density perturbations oscillate in space and time, and the dispersion relation of the oscillations matches that of ion acoustic waves, which are long-wavelength, electrostatic, density waves.

  17. Ion acoustic shock waves in degenerate plasmas

    SciTech Connect

    Akhtar, N.; Hussain, S.

    2011-07-15

    Korteweg de Vries Burgers equation for negative ion degenerate dissipative plasma has been derived using reductive perturbation technique. The quantum hydrodynamic model is used to study the quantum ion acoustic shock waves. The effects of different parameters on quantum ion acoustic shock waves are studied. It is found that quantum parameter, electrons Fermi temperature, temperature of positive and negative ions, mass ratio of positive to negative ions, viscosity, and density ratio have significant impact on the shock wave structure in negative ion degenerate plasma.

  18. The behavior of acoustic waves in the lakes bottom sediments.

    NASA Astrophysics Data System (ADS)

    Krylov, Pavel; Nourgaliev, Danis; Yasonov, Pavel

    2016-04-01

    Seismic studies are used for various tasks, such as the study of the bottom sediments properties, finding sunken objects, reconstruction the reservoir history, etc. Multiple acoustic waves are an enormous obstacle in obtaining full seismic record. Multiples from the bottom of a body of water (the surface of the base of water and the rock or sediment beneath it) and the air-water surface are common in lake seismic data. Multiple reflections on the seismic cross-sections are usually located on the double distance from the air/water surface. However, sometime multiple reflections from liquid deposits cannot be generated or they reflected from the deeper horizons. It is observed the phenomenon of changes in reflectance of the water/weakly consolidated sediments acoustic boundary under the influence of the acoustic wave. This phenomenon lies in the fact that after the first acoustic impact and reflection of acoustic wave for some time the reflectance of this boundary remains close to 0. This event on a cross-section can explain by the short-term changes in the properties of bottom sediments under the influence of shock? acoustic wave, with a further reduction of these properties to the next wave generation (generation period of 2 seconds). Perhaps in these deposits occurs thixotropic process. The paper presents the seismic acoustic cross-sections of Lake Balkhash (Kazakhstan), Turgoyak (Russia). The work was carried out according to the Russia Government's Program of Competitive Growth of Kazan Federal University, supported by the grant provided to the Kazan State University for performing the state program in the field of scientific research, and partially supported by the Russian Foundation for Basic research (grants № 14-05-00785, 16-35-00452).

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Raising Photoemission Efficiency with Surface Acoustic Waves

    SciTech Connect

    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.

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

    PubMed Central

    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

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

    PubMed

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

    2016-07-01

    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

  3. Surface acoustic wave/silicon monolithic sensor/processor

    NASA Technical Reports Server (NTRS)

    Kowel, S. T.; Kornreich, P. G.; Nouhi, A.; Kilmer, R.; Fathimulla, M. A.; Mehter, E.

    1983-01-01

    A new technique for sputter deposition of piezoelectric zinc oxide (ZnO) is described. An argon-ion milling system was converted to sputter zinc oxide films in an oxygen atmosphere using a pure zinc oxide target. Piezoelectric films were grown on silicon dioxide and silicon dioxide overlayed with gold. The sputtered films were evaluated using surface acoustic wave measurements, X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and resistivity measurements. The effect of the sputtering conditions on the film quality and the result of post-deposition annealing are discussed. The application of these films to the generation of surface acoustic waves is also discussed.

  4. Nonlinear surface acoustic waves in cubic crystals

    NASA Astrophysics Data System (ADS)

    Kumon, Ronald Edward

    Model equations developed by Hamilton, Il'inskii, and Zabolotskaya [J. Acoust. Soc. Am. 105, 639-651 (1999)] are used to perform theoretical and numerical studies of nonlinear surface acoustic waves in a variety of nonpiezoelectric cubic crystals. The basic theory underlying the model equations is outlined, quasilinear solutions of the equations are derived, and expressions are developed for the shock formation distance and nonlinearity coefficient. A time-domain equation corresponding to the frequency-domain model equations is derived and shown to reduce to a time-domain equation introduced previously for Rayleigh waves [E. A. Zabolotskaya, J. Acoust. Soc. Am. 91, 2569-2575 (1992)]. Numerical calculations are performed to predict the evolution of initially monofrequency surface waves in the (001), (110), and (111) planes of the crystals RbCl, KCl, NaCl, CaF2, SrF2, BaF2, C (diamond), Si, Ge, Al, Ni, Cu in the moverline 3m point group, and the crystals Cs-alum, NH4- alum, and K-alum in the moverline 3 point group. The calculations are based on measured second- and third- order elastic constants taken from the literature. Nonlinearity matrix elements which describe the coupling strength of harmonic interactions are shown to provide a powerful tool for characterizing waveform distortion. Simulations in the (001) and (110) planes show that in certain directions the velocity waveform distortion may change in sign, generation of one or more harmonies may be suppressed and shock formation postponed, or energy may be transferred rapidly to the highest harmonics and shock formation enhanced. Simulations in the (111) plane show that the nonlinearity matrix elements are generally complex-valued, which may lead to asymmetric distortion and the appearance of low frequency oscillations near the peaks and shocks in the velocity waveforms. A simple transformation based on the phase of the nonlinearity matrix is shown to provide a reasonable approximation of asymmetric waveform

  5. Exciton transport by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    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.

  6. High-frequency shear-horizontal surface acoustic wave sensor

    DOEpatents

    Branch, Darren W

    2013-05-07

    A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

  7. High-frequency shear-horizontal surface acoustic wave sensor

    SciTech Connect

    Branch, Darren W

    2014-03-11

    A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

  8. Deep ocean circulation by acoustic-gravity waves: from snowball to greenhouse earth

    NASA Astrophysics Data System (ADS)

    Kadri, Usama

    2015-04-01

    Acoustic-gravity waves are compression-type waves propagating with amplitudes governed by the restoring force of gravity. They are generated, among others, by wind-wave interactions, surface waves interactions, submarine earthquakes, and movements of ice-blocks. We show that acoustic-gravity waves contribute to deep ocean water transport through different climate timelines: from snowball to greenhouse earth; they cause chaotic flow trajectories of individual water parcels, which can be transported up to a few centimetres per second.

  9. Topological charge pump by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    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. Potential wells for classical acoustic waves

    NASA Astrophysics Data System (ADS)

    Chen, Shi; Lin, ShuYu; Mo, RunYang; Fu, ZhiQiang

    2014-01-01

    The acceleration theorem of Bloch waves is utilized to construct random potential wells for classical acoustic waves in systems composed of alternating `cavities' and `couplers'. One prominent advantage of this method is these `cavities' and `couplers' are all monolayer structures. It allows forming more compact classical potential wells, which leads to the miniaturization of acoustic devices. We systematically investigate properties of harmonic, tangent, hyperbolic function, and square classical potential wells in quasi-periodic superlattices. Results show these classical potential wells are analogues of quantum potential wells. Thus some technologies and concepts in quantum potential well fields may be generalized to classical acoustic wave fields. In addition, some abnormal cases regarding forming classical potential wells are also found.

  11. Observations of acoustic surface waves in outdoor sound propagation

    NASA Astrophysics Data System (ADS)

    Albert, Donald G.

    2003-05-01

    Acoustic surface waves have been detected propagating outdoors under natural conditions. Two critical experimental conditions were employed to ensure the conclusive detection of these waves. First, acoustic pulses rather than a continuous wave source allowed an examination of the waveform shape and avoided the masking of wave arrivals. Second, a snow cover provided favorable ground impedance conditions for surface waves to exist. The acoustic pulses were generated by blank pistol shots fired 1 m above the snow. The resultant waveforms were measured using a vertical array of six microphones located 60 m away from the source at heights between 0.1 and 4.75 m. A strong, low frequency ``tail'' following the initial arrival was recorded near the snow surface. This tail, and its exponential decay with height (z) above the surface (~e-αz), are diagnostic features of surface waves. The measured attenuation coefficient α was 0.28 m-1. The identification of the surface wave is confirmed by comparing the measured waveforms with waveforms predicted by the theoretical evaluation of the explicit surface wave pole term using residue theory.

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

    DOEpatents

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Acoustic waves superimposed on incompressible flows

    NASA Technical Reports Server (NTRS)

    Hodge, Steve

    1990-01-01

    The use of incompressible approximations in deriving solutions to the Lighthill wave equation was investigated for problems where an analytical solution could be found. A particular model problem involves the determination of the sound field of a spherical oscillating bubble in an ideal fluid. It is found that use of incompressible boundary conditions leads to good approximations in the important region of high acoustic wave number.

  15. Acoustic wave levitation: Handling of components

    NASA Astrophysics Data System (ADS)

    Vandaele, Vincent; Delchambre, Alain; Lambert, Pierre

    2011-06-01

    Apart from contact micromanipulation, there exists a large variety of levitation techniques among which standing wave levitation will be proposed as a way to handle (sub)millimetric components. This paper will compare analytical formulas to calculate the order of magnitude of the levitation force. It will then describe digital simulation and experimental levitation setup. Stable levitation of various components (cardboard, steel washer, ball, ceramic capacity, water droplet) was shown along 5 degrees of freedom: The only degree of freedom that could not be mastered was the rotation about the symmetry axis of the acoustic field. More importantly, the present work will show the modification of the orientation of the radial force component in the presence of an object disturbing the acoustic field. This property can be used as a new feeding strategy as it means that levitating components are spontaneously pushed toward grippers in an acoustic plane standing wave.

  16. Wave Phenomena in an Acoustic Resonant Chamber

    ERIC Educational Resources Information Center

    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.…

  17. Acoustic-Gravity Waves from Bolide Sources

    NASA Astrophysics Data System (ADS)

    Revelle, Douglas O.

    2008-06-01

    We have developed a new approach to modeling the acoustic-gravity wave (AGW) radiation from bolide sources. This first effort involves entry modeling of bolide sources that have available satellite data through procedures developed in ReVelle (Earth Moon Planets 95, 441-476, 2004a; in: A. Milani, G. Valsecchi, D. Vokrouhlicky (eds) NEO Fireball Diversity: Energetics-based Entry Modeling and Analysis Techniques, Near-earth Objects: Our Celestial Neighbors (IAU S236), 2007b). Results from the entry modeling are directly coupled to AGW production through line source blast wave theory for the initial wave amplitude and period at x=10 (at 10 blast wave radii and perpendicular to the trajectory). The second effort involves the prediction of the formation and or dominance of the propagation of the atmospheric Lamb, edge-wave composite mode in a viscous fluid (Pierce, J. Acoust. Soc. Amer. 35, 1798-1807, 1963) as a function of the source energy, horizontal range and source altitude using the Lamb wave frequency that was deduced directly during the entry modeling and that is used as a surrogate for the source energy. We have also determined that Lamb wave production by bolides at close range decreases dramatically as either the source energy decreases or the source altitude increases. Finally using procedures in Gill ( Atmospheric-Ocean Dynamics, 1982) and in Tolstoy ( Wave Propagation, 1973), we have analyzed two simple dispersion relationships and have calculated the expected dispersion for the Lamb edge-wave mode and for the excited, propagating internal acoustic waves. Finally, we have used the above formalism to fully evaluate these techniques for four large bolides, namely: the Tunguska bolide of June 30, 1908; the Revelstoke bolide of March 31, 1965; the Crete bolide of June 6, 2002 and the Antarctic bolide of September 3, 2004. Due to page limitations, we will only present results in detail for the Revelstoke bolide.

  18. Nozzleless Spray Cooling Using Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    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 .

  19. Standing surface acoustic wave (SSAW)-based cell washing

    PubMed Central

    Li, Sixing; Ding, Xiaoyun; Mao, Zhangming; Chen, Yuchao; Nama, Nitesh; Guo, Feng; Li, Peng; Wang, Lin; Cameron, Craig E.; Huang, Tony Jun

    2014-01-01

    Cell/bead washing is an indispensable sample preparation procedure used in various cell studies and analytical processes. In this article, we report a standing surface acoustic wave (SSAW)-based microfluidic device for cell and bead washing in a continuous flow. In our approach, the acoustic radiation force generated in a SSAW field is utilized to actively extract cells or beads from their original medium. A unique configuration of tilted-angle standing surface acoustic wave (taSSAW) is employed in our device, enabling us to wash beads with >98% recovery rate and >97% washing efficiency. We also demonstrate the functionality of our device by preparing high-purity (>97%) white blood cells from lysed blood samples through cell washing. Our SSAW-based cell/bead washing device has the advantages of label-free manipulation, simplicity, high biocompatibility, high recovery rate, and high washing efficiency. It can be useful for many lab-on-a-chip applications. PMID:25372273

  20. Hydromagnetic simulation of the ionospheric disturbances generated by the 2011 Tohoku-oki tsunami and associated acoustic-gravity waves

    NASA Astrophysics Data System (ADS)

    Kherani, E. A.; Lognonne, P. H.; Paula, E. R.; Rolland, L. M.

    2013-05-01

    Owing to the natural disturbances such as Earth quake/tsunami and tropospheric convection, Acosutic gravity waves (AGWs) are excited in the troposphere. These AGWs propagates upward to the thermosphere, attain large amplitude therein and subsequently dissipate, leading to the excitation of secondary AGWs which mainly propagate horizontally. Both primary and secondary AGWs significantly modify the ionosphere, leading to the Total electron Content disturances, current and magnetic disturbances. Focus of the present work is the recent Japan tsunami that occurred on 11 March 2011 over Tohoku-Oki and caused enormous damage in terms of human life and infrastructures. Moreover, it triggered nuclear catastrophe that makes it a global disaster and much more alarming. The growing concern is towards failure of short-term forecasting of this event in spite that the Japan is densely populated with the various ground based seismic instrument as well with the GPS receivers that may detect the activities in the space related to the tsunami. However, owing to these dense networks, this event is examined much more thoroughly than other big events in the past, leading to the knowledge of various interesting aspects that may be helpful in the future for the short-term forecasting of such event. One such aspect is that the effects of the seismic activities occurring deep into the ocean, are detected much more efficiently and in varieties in space (in the overlying atmosphere and ionosphere) than over the ocean or Earth's surface. In the present work, hydrodynamic and hydromagnetic simulations of the atmospheric and ionospheric anomalies are performed for the Tohoku-Oki tsunami (11 March 2011). The Tsunami-Atmosphere-Ionosphere (TAI) coupling mechanism via AGWs is explored theoretically using the TAI coupled model. In this mechanism, tsunami in the ocean excites the AGWs in the atmosphere owing to the vertical uplift which subsequently interact with the ionosphere to gives rise density

  1. Acoustic wave-equation-based earthquake location

    NASA Astrophysics Data System (ADS)

    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.

  2. Properties of materials using acoustic waves

    NASA Astrophysics Data System (ADS)

    Apfel, R. E.

    1984-10-01

    Our goal of characterizing materials using acoustic waves was forwarded through a number of projects: (1) We have refined our modulated radiation pressure technique for characterizing the interfaces between liquids so that we can automatically track changes in interfacial tension over time due to contaminants, surfactants, etc. (2) We have improved and simplified our acoustic scattering apparatus for measuring distributions of the properties of microparticle samples, which will allow us to distinguish particulates in liquids by size, compressibility, and density. (3) We are continuing work on theoretical approaches to nonlinear acoustics which should permit us to cast problems with geometric and other complexities into a manageable form. (4) Our studies of cavitation have enabled us to derive an analytic expression which predicts the acoustic pressure threshold for cavitation at the micrometer scale - where surface tension effects are important. This work has relevance to the consideration of possible bioeffects from diagnostic ultrasound. (5) Other projects include the calibration of hydrophones using acoustically levitated samples, and the investigation of solitary waves of the sort discovered by Wu, Keolian and Rudnick.

  3. Formation of ion acoustic solitary waves upstream of the earth's bow shock. [in solar wind

    NASA Technical Reports Server (NTRS)

    Pangia, M. J.; Lee, N. C.; Parks, G. K.

    1985-01-01

    The turbulent plasma development of Lee and Parks is applied to the solar wind approaching the earth's bow shock region. The ponderomotive force contribution is due to ion acoustic waves propagating in the direction of the ambient magnetic field. In this case, the envelope of the ion acoustic wave is shown to satisfy the cubic Schroedinger equation. Modulational instabilities exist for waves in the solar wind, thereby predicting the generation of solitary waves. This analysis further identifies that the ion acoustic waves which exhibit this instability have short wavelengths.

  4. Method and apparatus for generating acoustic energy

    DOEpatents

    Guerrero, Hector N.

    2002-01-01

    A method and apparatus for generating and emitting amplified coherent acoustic energy. A cylindrical transducer is mounted within a housing, the transducer having an acoustically open end and an acoustically closed end. The interior of the transducer is filled with an active medium which may include scattering nuclei. Excitation of the transducer produces radially directed acoustic energy in the active medium, which is converted by the dimensions of the transducer, the acoustically closed end thereof, and the scattering nuclei, to amplified coherent acoustic energy directed longitudinally within the transducer. The energy is emitted through the acoustically open end of the transducer. The emitted energy can be used for, among other things, effecting a chemical reaction or removing scale from the interior walls of containment vessels.

  5. Radiation dominated acoustophoresis driven by surface acoustic waves.

    PubMed

    Guo, Jinhong; Kang, Yuejun; Ai, Ye

    2015-10-01

    Acoustophoresis-based particle manipulation in microfluidics has gained increasing attention in recent years. Despite the fact that experimental studies have been extensively performed to demonstrate this technique for various microfluidic applications, numerical simulation of acoustophoresis driven by surface acoustic waves (SAWs) has still been largely unexplored. In this work, a numerical model taking into account the acoustic-piezoelectric interaction was developed to simulate the generation of a standing surface acoustic wave (SSAW) field and predict the acoustic pressure field in the liquid. Acoustic radiation dominated particle tracing was performed to simulate acoustophoresis of particles with different sizes undergoing a SSAW field. A microfluidic device composed of two interdigital transducers (IDTs) for SAW generation and a microfluidic channel was fabricated for experimental validation. Numerical simulations could well capture the focusing phenomenon of particles to the pressure nodes in the experimental observation. Further comparison of particle trajectories demonstrated considerably quantitative agreement between numerical simulations and experimental results with fitting in the applied voltage. Particle switching was also demonstrated using the fabricated device that could be further developed as an active particle sorting device. PMID:26070191

  6. Nonlinear acoustic wave propagation in atmosphere

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.

    1985-01-01

    A model problem that simulates an atmospheric acoustic wave propagation situation that is nonlinear is considered. The model is derived from the basic Euler equations for the atmospheric flow and from the regular perturbations for the acoustic part. The nonlinear effects are studied by obtaining two successive linear problems in which the second one involves the solution of the first problem. Well posedness of these problems is discussed and approximations of the radiation boundary conditions that can be used in numerical simulations are presented.

  7. Nonlinear holography for acoustic wave detection

    NASA Astrophysics Data System (ADS)

    Bortolozzo, U.; Dolfi, D.; Huignard, J. P.; Molin, S.; Peigné, A.; Residori, S.

    2015-03-01

    A liquid crystal medium is used to perform nonlinear dynamic holography and is coupled with multimode optical fibers for optical sensing applications. Thanks to the adaptive character of the nonlinear holography, and to the sensitivity of the multimode fibers, we demonstrate that the system is able to perform efficient acoustic wave detection even with noisy signals. The detection limit is estimated and multimode versus monomode optical fiber are compared. Finally, a wavelength multiplexing protocol is implemented for the spatial localization of the acoustic disturbances.

  8. Nonlinear acoustic wave propagation in atmosphere

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.

    1986-01-01

    In this paper a model problem is considered that simulates an atmospheric acoustic wave propagation situation that is nonlinear. The model is derived from the basic Euler equations for the atmospheric flow and from the regular perturbations for the acoustic part. The nonlinear effects are studied by obtaining two successive linear problems in which the second one involves the solution of the first problem. Well-posedness of these problems is discussed and approximations of the radiation boundary conditions that can be used in numerical simulations are presented.

  9. A surface-acoustic-wave-based cantilever bio-sensor.

    PubMed

    De Simoni, Giorgio; Signore, Giovanni; Agostini, Matteo; Beltram, Fabio; Piazza, Vincenzo

    2015-06-15

    A scalable surface-acoustic-wave- (SAW-) based cantilevered device for portable bio-chemical sensing applications is presented. Even in the current, proof-of-principle implementation this architecture is shown to outperform commercial quartz-crystal microbalances in terms of sensitivity. Adhesion of analytes on a functionalized surface of the cantilever shifts the resonant frequency of a SAW-generating transducer due to the stress-induced variation of the speed of surface acoustic modes. We discuss the relevance of this approach for diagnostics applications based on miniaturized devices. PMID:25643594

  10. Single crystal metal wedges for surface acoustic wave propagation

    DOEpatents

    Fisher, Edward S.

    1982-01-01

    An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

  11. Single crystal metal wedges for surface acoustic wave propagation

    DOEpatents

    Fisher, E.S.

    1980-05-09

    An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

  12. Properties of materials using acoustic waves

    NASA Astrophysics Data System (ADS)

    Apfel, R. E.

    1985-10-01

    Our goal of characterizing materials using acoustic waves was forwarded through a number of projects: (1) We have derived a theory, and tested it on tissues, for predicting the composition of composite materials using mixture rules, such as the one we derived for the nonlinear parameter two years ago; (2) We have published one article and another is in review on our use of modulated acoustic radiation pressure on levitated drops to characterize interfaces with and without surfactants. We have begun to study in a systematic way the nonlinear dynamics of drops, including drop fission: (3) we have improved apparatus for 30 MHz ultrasonic scattering from microparticles (approx. micron size), which should allow us to discriminate between different microparticles in a liquid; (4) We have begun to study the nonlinear mechanics of hydrodynamic solitons in cylindrical (2-d) geometry; and (5) We have been studying the use of acoustic levitation for transducer calibration.

  13. Wave Motion Electric Generator

    SciTech Connect

    Jacobi, E. F.; Winkler, R. J.

    1983-12-27

    Set out herein is an electrical generator conformed for installation in a buoy, the generator comprising an inverted pendulum having two windings formed at the free end thereof and aligned to articulate between two end stops each provided with a magnetic circuit. As the loops thus pass through the magnetic circuit, electrical current is induced which may be rectified through a full way rectifier to charge up a storage battery. The buoy itself may be ballasted to have its fundamental resonance at more than double the wave frequency with the result that during each passing of a wave at least two induction cycles occur.

  14. Ocean wave electric generators

    SciTech Connect

    Rosenberg, H.R.

    1986-02-04

    This patent describes an apparatus for generating electricity from ocean waves. It consists of: 1.) a hollow buoyant duck positioned in the path of waves including a core about the center axis of which the duck rotates, a lower chamber portion having liquid therein and an upper chamber portion having air therein. The air is alternately compressed and expanded by the liquid in the chamber during the rotational motion of the duck caused by waves. A turbine mounted in the upper portion of the duck is driven by the compressed and expanded air. A generator is coupled to the turbine and operated to produce electrical energy and an air bulb; 2.) a spine having a transverse axial shaft anchoring the spine to the ocean floor. The upper portion of the spine engages the duck to maintain the duck in position. The spine has a curved configuration to concentrate and direct wave energy. The spine configuration acts as a scoop to increase the height of wave peaks and as a foil to increase the depth of wave troughs.

  15. Turbulence generation by waves

    SciTech Connect

    Kaftori, D.; Nan, X.S.; Banerjee, S.

    1995-12-31

    The interaction between two-dimensional mechanically generated waves, and a turbulent stream was investigated experimentally in a horizontal channel, using a 3-D LDA synchronized with a surface position measuring device and a micro-bubble tracers flow visualization with high speed video. Results show that although the wave induced orbital motion reached all the way to the wall, the characteristics of the turbulence wall structures and the turbulence intensity close to the wall were not altered. Nor was the streaky nature of the wall layer. On the other hand, the mean velocity profile became more uniform and the mean friction velocity was increased. Close to the free surface, the turbulence intensity was substantially increased as well. Even in predominantly laminar flows, the introduction of 2-D waves causes three dimensional turbulence. The turbulence enhancement is found to be proportional to the wave strength.

  16. Reconstructing surface wave profiles from reflected acoustic pulses.

    PubMed

    Walstead, Sean P; Deane, Grant B

    2013-05-01

    Surface wave shapes are determined by analyzing underwater reflected acoustic signals. The acoustic signals (of nominal frequency 200 kHz) are forward scattered from the underside of surface waves that are generated in a wave tank and scaled to model smooth ocean swell. An inverse processing algorithm is designed and implemented to reconstruct the surface displacement profiles of the waves over one complete period. The inverse processing uses the surface scattered pulses collected at the receiver, an initial wave profile (two are considered), and a broadband forward scattering model based on Kirchhoff's diffraction formula to iteratively adjust the surface until it is considered optimized or reconstructed. Two physical length scales over which information can be known about the surface are confirmed. An outer length scale, the Fresnel zone surrounding each specular reflection point, is the only region where optimized surfaces resulting from each initial profile converge within a resolution set by the inner length scale, a quarter-wavelength of the acoustic pulse. The statistical confidence of each optimized surface is also highest within a Fresnel zone. Future design considerations are suggested such as an array of receivers that increases the region of surface reconstruction by a factor of 2 to 3. PMID:23654368

  17. Wireless Multiplexed Surface Acoustic Wave Sensors Project

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.

    2014-01-01

    Wireless Surface Acoustic Wave (SAW) Sensor is a new technology for obtaining multiple, real-time measurements under extreme environmental conditions. This project plans to develop a wireless multiplexed sensor system that uses SAW sensors, with no batteries or semiconductors, that are passive and rugged, can operate down to cryogenic temperatures and up to hundreds of degrees C, and can be used to sense a wide variety of parameters over reasonable distances (meters).

  18. Support minimized inversion of acoustic and elastic wave scattering

    SciTech Connect

    Safaeinili, A.

    1994-04-24

    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.

  19. Modulation of Radio Frequency Signals by Nonlinearly Generated Acoustic Fields

    NASA Astrophysics Data System (ADS)

    Johnson, Spencer Joseph

    Acousto-electromagnetic scattering is a process in which an acoustic excitation is utilized to induce modulation on an electromagnetic (EM) wave. This phenomenon can be exploited in remote sensing and detection schemes whereby target objects are mechanically excited by high powered acoustic waves resulting in unique object characterizations when interrogated with EM signals. Implementation of acousto-EM sensing schemes, however, are limited by a lack of fundamental understanding of the nonlinear interaction between acoustic and EM waves and inefficient simulation methods in the determination of the radiation patterns of higher order scattered acoustic fields. To address the insufficient simulation issue, a computationally efficient mathematical model describing higher order scattered sound fields, particularly of third-order in which a 40x increase in computation speed is achieved, is derived using a multi-Gaussian beam (MGB) expansion that expresses the sound field of any arbitrary axially symmetric beam as a series of Gaussian base functions. The third-order intermodulation (IM3) frequency components are produced by considering the cascaded nonlinear second-order effects when analyzing the interaction between the first- and second-order frequency components during the nonlinear scattering of sound by sound from two noncollinear ultrasonic baffled piston sources. The theory is extended to the modeling of the sound beams generated by parametric transducer arrays, showing that the MGB model can be efficiently used to calculate both the second- and third-order sound fields of the array. Additionally, a near-to-far-field (NTFF) transformation method is developed to model the far-field characteristics of scattered sound fields, extending Kirchhoff's theorem, typically applied to EM waves, determining the far-field patterns of an acoustic source from amplitude and phase measurements made in the near-field by including the higher order sound fields generated by the

  20. Interaction of surface acoustic waves with moving vortex structures in superconducting films

    SciTech Connect

    Gutlyansky, E. D.

    2007-07-15

    A method is proposed for describing a moving film vortex structure and its interaction with surface acoustic waves. It is shown that the moving vortex structure can amplify (generate) surface acoustic waves. In contrast to a similar effect in semiconductor films, this effect can appear when the velocity of the vortex structure is much lower than the velocity of the surface acoustic waves. A unidirectional collective mode is shown to exist in the moving vortex structure. This mode gives rise to an acoustic analogue of the diode effect that is resonant in the velocity of the vortex structure. This acoustic effect is manifested as an anomalous attenuation of the surface acoustic waves in the direction of the vortex-structure motion and as the absence of this attenuation for the propagation in the opposite direction.

  1. Surface acoustic wave-driven planar light-emitting device

    NASA Astrophysics Data System (ADS)

    Cecchini, Marco; De Simoni, Giorgio; Piazza, Vincenzo; Beltram, Fabio; Beere, H. E.; Ritchie, D. A.

    2004-10-01

    Electroluminescence emission controlled by means of surface acoustic waves (SAWs) in planar light-emitting diodes (pLEDs) is demonstrated. Interdigital transducers for SAW generation were integrated onto pLEDs fabricated following the scheme which we have recently developed [Cecchini et al., Appl. Phys. Lett. 82, 636 (2003)]. Current-voltage, light-voltage, and photoluminescence characteristics are presented at cryogenic temperatures. We argue that this scheme represents a valuable building block for advanced optoelectronic architectures.

  2. Torsional waves excited by electromagnetic-acoustic transducers during guided-wave acoustic inspection of pipelines

    NASA Astrophysics Data System (ADS)

    Murav'eva, O. V.; Len'kov, S. V.; Murashov, S. A.

    2016-01-01

    A theory of propagation of torsional waves excited by an electromagnetic-acoustic transducer in a pipe is proposed. This theory takes into account the excitation parameters, geometry, viscosity, and the elastic characteristics of an object. The main testing parameters (the frequency and geometry of the transducer) that determine the possibilities of guided-wave testing of pipelines of various dimensions using torsional waves are theoretically substantiated.

  3. Nonlinear ion acoustic waves scattered by vortexes

    NASA Astrophysics Data System (ADS)

    Ohno, Yuji; Yoshida, Zensho

    2016-09-01

    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., the vortex equation is independent of the wave fields). This model describes a minimal departure from the integrable KP system. By the Painlevé test, we delineate how the vorticity term violates integrability, bringing about an essential three-dimensionality to the solutions. By numerical simulation, we show how the solitons are scattered by vortexes and become chaotic.

  4. Radio wave propagation and acoustic sounding

    NASA Astrophysics Data System (ADS)

    Singal, S. P.

    Radio wave propagation of the decimetric and centimetric waves depends to a large extent on the boundary layer meteorological conditions which give rise to severe fadings, very often due to multipath propagation. Sodar is one of the inexpensive remote sensing techniques which can be employed to probe the boundary layer structure. In the paper a historical perspective has been given of the simultaneously conducted studies on radio waves and sodar at various places. The radio meteorological information needed for propagation studies has been clearly spelt out and conditions of a ray path especially in the presence of a ducting layer have been defined as giving rise to fading or signal enhancement conditions. Finally the potential of the sodar studies to obtain information about the boundary layer phenomena has been stressed, clearly spelling out the use of acoustic sounding in radio wave propagation studies.

  5. Thomson-Scattering Study of the Subharmonic Decay of Ion-Acoustic Waves Driven by the Brillouin Instability

    NASA Astrophysics Data System (ADS)

    Bandulet, H. C.; Labaune, C.; Lewis, K.; Depierreux, S.

    2004-07-01

    Thomson scattering (TS) has been used to investigate the two-ion decay instability of ion acoustic waves generated by stimulated Brillouin scattering in an underdense CH plasma. Two complementary TS diagnostics, spectrally and spatially resolved, demonstrate the occurrence of the subharmonic decay of the primary ion acoustic wave into two secondary waves. The study of the laser intensity dependence shows that the secondary ion acoustic waves are correlated with the SBS reflectivity saturation, at a level of a few percent.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Numerical Investigations of High Pressure Acoustic Waves in Resonators

    NASA Technical Reports Server (NTRS)

    Athavale, Mahesh; Pindera, Maciej; Daniels, Christopher C.; Steinetz, Bruce M.

    2004-01-01

    This presentation presents work on numerical investigations of nonlinear acoustic phenomena in resonators that can generate high-pressure waves using acoustic forcing of the flow. Time-accurate simulations of the flow in a closed cone resonator were performed at different oscillation frequencies and amplitudes, and the numerical results for the resonance frequency and fluid pressure increase match the GRC experimental data well. Work on cone resonator assembly simulations has started and will involve calculations of the flow through the resonator assembly with and without acoustic excitation. A new technique for direct calculation of resonance frequency of complex shaped resonators is also being investigated. Script-driven command procedures will also be developed for optimization of the resonator shape for maximum pressure increase.

  8. Propagation characteristics of acoustic waves in snow

    NASA Astrophysics Data System (ADS)

    Capelli, Achille; Kapil, Jagdish Chandra; Reiweger, Ingrid; Schweizer, Jürg; Or, Dani

    2015-04-01

    Acoustic emission analysis is a promising technique for monitoring snow slope stability with potential for application in early warning systems for avalanches. Current research efforts focus on identification and localization of acoustic emission features preceding snow failure and avalanches. However, our knowledge of sound propagation characteristics in snow is still limited. A review of previous studies showed that significant gaps exist and that the results of the various studies are partly contradictory. Furthermore, sound velocity and attenuation have been determined for the frequency range below 10 kHz, while recent snow failure experiments suggest that the peak frequency is in the ultrasound range between 30 kHz to 500 kHz. We therefore studied the propagation of pencil lead fracture (PLF) signals through snow in the ultrasound frequency range. This was achieved by performing laboratory experiments with columns of artificially produced snow of varying density and temperature. The attenuation constant was obtained by varying the size of the columns to eliminate possible influences of the snow-sensor coupling. The attenuation constant was measured for the entire PLF burst signal and for single frequency components. The propagation velocity was calculated from the arrival time of the acoustic signal. We then modelled the sound propagation for our experimental setup using Biot's model for wave propagation in porous media. The Model results were in good agreement with our experimental results. For the studied samples, the acoustic signals propagated as fast and slow longitudinal waves, but the main part of the energy was carried by the slow waves. The Young's modulus of our snow samples was determined from the sound velocity. This is highly relevant, as the elastic properties of snow are not well known.

  9. Acoustic and Cavitation Fields of Shock Wave Therapy Devices

    NASA Astrophysics Data System (ADS)

    Chitnis, Parag V.; Cleveland, Robin O.

    2006-05-01

    Extracorporeal shock wave therapy (ESWT) is considered a viable treatment modality for orthopedic ailments. Despite increasing clinical use, the mechanisms by which ESWT devices generate a therapeutic effect are not yet understood. The mechanistic differences in various devices and their efficacies might be dependent on their acoustic and cavitation outputs. We report acoustic and cavitation measurements of a number of different shock wave therapy devices. Two devices were electrohydraulic: one had a large reflector (HMT Ossatron) and the other was a hand-held source (HMT Evotron); the other device was a pneumatically driven device (EMS Swiss DolorClast Vet). Acoustic measurements were made using a fiber-optic probe hydrophone and a PVDF hydrophone. A dual passive cavitation detection system was used to monitor cavitation activity. Qualitative differences between these devices were also highlighted using a high-speed camera. We found that the Ossatron generated focused shock waves with a peak positive pressure around 40 MPa. The Evotron produced peak positive pressure around 20 MPa, however, its acoustic output appeared to be independent of the power setting of the device. The peak positive pressure from the DolorClast was about 5 MPa without a clear shock front. The DolorClast did not generate a focused acoustic field. Shadowgraph images show that the wave propagating from the DolorClast is planar and not focused in the vicinity of the hand-piece. All three devices produced measurable cavitation with a characteristic time (cavitation inception to bubble collapse) that varied between 95 and 209 μs for the Ossatron, between 59 and 283 μs for the Evotron, and between 195 and 431 μs for the DolorClast. The high-speed camera images show that the cavitation activity for the DolorClast is primarily restricted to the contact surface of the hand-piece. These data indicate that the devices studied here vary in acoustic and cavitation output, which may imply that the

  10. High-Temperature Surface-Acoustic-Wave Transducer

    NASA Technical Reports Server (NTRS)

    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.

  11. Electron Acoustic Waves in Pure Ion Plasmas

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.; O'Neil, T. M.; Valentini, F.

    2012-10-01

    Electron Acoustic Waves (EAWs) are the low-frequency branch of near-linear Langmuir (plasma) waves: the frequency is such that the complex dielectric function (Dr, Di) has Dr= 0; and ``flattening'' of f(v) near the wave phase velocity vph gives Di=0 and eliminates Landau damping. Here, we observe standing axisymmetric EAWs in a pure ion column.footnotetextF. Anderegg, et al., Phys. Rev. Lett. 102, 095001 (2009). At low excitation amplitudes, the EAWs have vph˜1.4 v, in close agreement with near-linear theory. At moderate excitation strengths, EAW waves are observed over a range of frequencies, with 1.3 v < vph< 2.1 v. Here, the final wave frequency may differ from the excitation frequency since the excitation modifies f (v); and recent theory analyzes frequency shifts from ``corners'' of a plateau at vph.footnotetextF. Valentini et al., arXiv:1206.3500v1. Large amplitude EAWs have strong phase-locked harmonic content, and experiments will be compared to same-geometry simulations, and to simulations of KEENfootnotetextB. Afeyan et al., Proc. Inertial Fusion Sci. and Applications 2003, A.N.S. Monterey (2004), p. 213. waves in HEDLP geometries.

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

    SciTech Connect

    Liu, Xiaozhou Zhang, Lue; Wang, Xiangda; Gong, Xiufen

    2015-10-28

    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.

  13. Observations of dust acoustic waves driven at high frequencies: Finite dust temperature effects and wave interference

    SciTech Connect

    Thomas, Edward Jr.; Fisher, Ross; Merlino, Robert L.

    2007-12-15

    An experiment has been performed to study the behavior of dust acoustic waves driven at high frequencies (f>100 Hz), extending the range of previous work. In this study, two previously unreported phenomena are observed--interference effects between naturally excited dust acoustic waves and driven dust acoustic waves, and the observation of finite dust temperature effects on the dispersion relation.

  14. Dual-mode acoustic wave biosensors microarrays

    NASA Astrophysics Data System (ADS)

    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.

  15. Volcanoes generate devastating waves

    SciTech Connect

    Lockridge, P. )

    1988-01-01

    Although volcanic eruptions can cause many frightening phenomena, it is often the power of the sea that causes many volcano-related deaths. This destruction comes from tsunamis (huge volcano-generated waves). Roughly one-fourth of the deaths occurring during volcanic eruptions have been the result of tsunamis. Moreover, a tsunami can transmit the volcano's energy to areas well outside the reach of the eruption itself. Some historic records are reviewed. Refined historical data are increasingly useful in predicting future events. The U.S. National Geophysical Data Center/World Data Center A for Solid Earth Geophysics has developed data bases to further tsunami research. These sets of data include marigrams (tide gage records), a wave-damage slide set, digital source data, descriptive material, and a tsunami wall map. A digital file contains information on methods of tsunami generation, location, and magnitude of generating earthquakes, tsunami size, event validity, and references. The data can be used to describe areas mot likely to generate tsunamis and the locations along shores that experience amplified effects from tsunamis.

  16. Prospects for coupling Surface Acoustic Waves to superconducting qubits

    NASA Astrophysics Data System (ADS)

    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.

  17. Nonextensive dust-acoustic solitary waves

    SciTech Connect

    Tribeche, M.; Merriche, A.

    2011-03-15

    The seminal paper of Mamun et al. [Phys. Plasmas 3, 702 (1996)] is revisited within the theoretical framework of the Tsallis statistical mechanics. The nonextensivity may originate from the correlation or long-range interactions in the dusty plasma. It is found that depending on whether the nonextensive parameter q is positive or negative, the dust-acoustic (DA) soliton exhibits compression for q<0 and rarefaction for q>0. The lower limit of the Mach number for the existence of DA solitary waves is greater (smaller) than its Maxwellian counterpart in the case of superextensivity (subextensivity).

  18. Simulation of dust-acoustic waves

    SciTech Connect

    Winske, D.; Murillo, M.S.; Rosenberg, M.

    1998-12-01

    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 = {Lambda} = 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).

  19. Surface acoustic wave propagation in graphene film

    SciTech Connect

    Roshchupkin, Dmitry Plotitcyna, Olga; Matveev, Viktor; Kononenko, Oleg; Emelin, Evgenii; Irzhak, Dmitry; Ortega, Luc; Zizak, Ivo; Erko, Alexei; Tynyshtykbayev, Kurbangali; Insepov, Zinetula

    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.

  20. Acoustic gravity waves: A computational approach

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.; Dutt, P. K.

    1987-01-01

    This paper discusses numerical solutions of a hyperbolic initial boundary value problem that arises from acoustic wave propagation in the atmosphere. Field equations are derived from the atmospheric fluid flow governed by the Euler equations. The resulting original problem is nonlinear. A first order linearized version of the problem is used for computational purposes. The main difficulty in the problem as with any open boundary problem is in obtaining stable boundary conditions. Approximate boundary conditions are derived and shown to be stable. Numerical results are presented to verify the effectiveness of these boundary conditions.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Physics of thermo-acoustic sound generation

    NASA Astrophysics Data System (ADS)

    Daschewski, M.; Boehm, R.; Prager, J.; Kreutzbruck, M.; Harrer, A.

    2013-09-01

    We present a generalized analytical model of thermo-acoustic sound generation based on the analysis of thermally induced energy density fluctuations and their propagation into the adjacent matter. The model provides exact analytical prediction of the sound pressure generated in fluids and solids; consequently, it can be applied to arbitrary thermal power sources such as thermophones, plasma firings, laser beams, and chemical reactions. Unlike existing approaches, our description also includes acoustic near-field effects and sound-field attenuation. Analytical results are compared with measurements of sound pressures generated by thermo-acoustic transducers in air for frequencies up to 1 MHz. The tested transducers consist of titanium and indium tin oxide coatings on quartz glass and polycarbonate substrates. The model reveals that thermo-acoustic efficiency increases linearly with the supplied thermal power and quadratically with thermal excitation frequency. Comparison of the efficiency of our thermo-acoustic transducers with those of piezoelectric-based airborne ultrasound transducers using impulse excitation showed comparable sound pressure values. The present results show that thermo-acoustic transducers can be applied as broadband, non-resonant, high-performance ultrasound sources.

  3. Dust-acoustic rogue waves in a nonextensive plasma

    SciTech Connect

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

    2011-12-15

    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 Schroedinger equation. The critical wave-number threshold k{sub c}, which indicates where the modulational instability sets in, has been determined precisely for various regimes. Two different behaviors of k{sub c} against the nonextensive parameter q are found. For small k{sub c}, it is found that increasing q would lead to an increase of k{sub c} until q approaches a certain value q{sub c}, then further increase of q beyond q{sub c} decreases the value of k{sub c}. For large k{sub c}, the critical wave-number threshold k{sub 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.

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

    PubMed

    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

  5. Dual mode acoustic wave sensor for precise pressure reading

    NASA Astrophysics Data System (ADS)

    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.

  6. Investigations of High Pressure Acoustic Waves in Resonators with Seal-Like Features

    NASA Technical Reports Server (NTRS)

    Daniels, Christopher C.; Steinetz, Bruce M.; Finkbeiner, Joshua R.; Li, Xiao-Fan; Raman, Ganesh

    2004-01-01

    1) Standing waves with maximum pressures of 188 kPa have been produced in resonators containing ambient pressure air; 2) Addition of structures inside the resonator shifts the fundamental frequency and decreases the amplitude of the generated pressure waves; 3) Addition of holes to the resonator does reduce the magnitude of the acoustic waves produced, but their addition does not prohibit the generation of large magnitude non-linear standing waves; 4) The feasibility of reducing leakage using non-linear acoustics has been confirmed.

  7. Porous silicon bulk acoustic wave resonator with integrated transducer

    PubMed Central

    2012-01-01

    We report that porous silicon acoustic Bragg reflectors and AlN-based transducers can be successfully combined and processed in a commercial solidly mounted resonator production line. The resulting device takes advantage of the unique acoustic properties of porous silicon in order to form a monolithically integrated bulk acoustic wave resonator. PMID:22776697

  8. Wave envelopes method for description of nonlinear acoustic wave propagation.

    PubMed

    Wójcik, J; Nowicki, A; Lewin, P A; Bloomfield, P E; Kujawska, T; Filipczyński, L

    2006-07-01

    A novel, free from paraxial approximation and computationally efficient numerical algorithm capable of predicting 4D acoustic fields in lossy and nonlinear media from arbitrary shaped sources (relevant to probes used in medical ultrasonic imaging and therapeutic systems) is described. The new WE (wave envelopes) approach to nonlinear propagation modeling is based on the solution of the second order nonlinear differential wave equation reported in [J. Wójcik, J. Acoust. Soc. Am. 104 (1998) 2654-2663; V.P. Kuznetsov, Akust. Zh. 16 (1970) 548-553]. An incremental stepping scheme allows for forward wave propagation. The operator-splitting method accounts independently for the effects of full diffraction, absorption and nonlinear interactions of harmonics. The WE method represents the propagating pulsed acoustic wave as a superposition of wavelet-like sinusoidal pulses with carrier frequencies being the harmonics of the boundary tone burst disturbance. The model is valid for lossy media, arbitrarily shaped plane and focused sources, accounts for the effects of diffraction and can be applied to continuous as well as to pulsed waves. Depending on the source geometry, level of nonlinearity and frequency bandwidth, in comparison with the conventional approach the Time-Averaged Wave Envelopes (TAWE) method shortens computational time of the full 4D nonlinear field calculation by at least an order of magnitude; thus, predictions of nonlinear beam propagation from complex sources (such as phased arrays) can be available within 30-60 min using only a standard PC. The approximate ratio between the computational time costs obtained by using the TAWE method and the conventional approach in calculations of the nonlinear interactions is proportional to 1/N2, and in memory consumption to 1/N where N is the average bandwidth of the individual wavelets. Numerical computations comparing the spatial field distributions obtained by using both the TAWE method and the conventional approach

  9. A New Acoustic Lens Design for Electromagnetic Shock Wave Lithotripters

    NASA Astrophysics Data System (ADS)

    Zhong, Pei; Smith, Nathan; Simmons, Neal W.; Sankin, Georgy

    2011-09-01

    The 3rd-generation electromagnetic (EM) shock wave lithotripters often have narrow focal width and high peak pressure compared to the original Dornier HM-3. In addition, the pressure waveform produced by a typical EM lithotripter has a secondary compressive wave following the tensile component that suppresses lithotripter pulse induced cavitation, which may impact negatively on stone comminution. These characteristic changes in the modern EM lithotripters may contribute in part to their reduced effectiveness observed clinically. To overcome these two drawbacks, we have designed a new acoustic lens for the Siemens Modularis EM lithotripter that produces an idealized pressure waveform similar to that of the HM-3 with broad focal width and low peak pressure. At acoustic pulse energy of 53 mJ, the new lens design enlarges the -6 dB focal width of the Modularis by 47% while significantly reducing the second compressive wave in the lithotripter pulse throughout its focal plane. After 2000 shocks, in vitro comminution produced by the original and new lens designs are 100% and 99% at the lithotripter focus, and 52±16% and 77±8% (p<0.001) at 10 mm off axis, respectively. Corresponding values for stones that are translated to mimic respiratory motion during shock wave lithotripsy are 83±4% and 91±1% (p<0.01), demonstrating the significant performance improvement provided by the new lens design.

  10. Confined aquifer as wave-guide and its responses to geo-acoustic waves

    NASA Astrophysics Data System (ADS)

    Jian, Wen-Bin; Chen, Bao-Ren; Lu, Hua-Fu

    1997-05-01

    On the basis of the hydro-geological model of a confined aquifer, the propagation mechanism of geo-acoustic waves along the confined aquifer outlined as a plate wave-guide is proposed. The harmonic frequency equation for geo-acoustic propagation along confined aquifer as waveguide is derived from Biot theory. The basic frequency of the confined aquifer with a deep well for geo-acoustic observation, located at Juxian county, Shandong province, China, is 35.0 Hz. By Wigner distribution of geo-acoustic signals observed at Juxian geo-acoustic well, the frequencies of geo-acoustics are basically the integral multiple of the basic frequency. The results show that the responses of the confined aquifer to geo-acoustic waves are characterized by frequency selection and frequency dependence. Only the waves whose frequency f is the integral multiple of basic frequency can propagate as guide waves in the aquifer, that is, the aquifer responds to the waves.

  11. Interfacial destabilization and atomization driven by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Qi, Aisha; Yeo, Leslie Y.; Friend, James R.

    2008-07-01

    Surface acoustic wave atomization is a rapid means for generating micron and submicron aerosol droplets. Little, however, is understood about the mechanisms by which these droplets form due to the complex hydrodynamic processes that occur across widely varying length and time scales. Through experiments, scaling theory, and simple numerical modeling, we elucidate the interfacial destabilization mechanisms that lead to droplet formation. Using a millimeter-order fluid drop exposed to surface acoustic waves as it sits atop a single-crystal lithium niobate piezoelectric substrate, large aerosol droplets on the length scale of the parent drop dimension are ejected through a whipping and pinch-off phenomenon, which occurs at the asymmetrically formed crest of the drop due to leakage of acoustic radiation at the Rayleigh angle. Smaller micron order droplets, on the other hand, are formed due to the axisymmetric breakup of cylindrical liquid jets that are ejected as a consequence of interfacial destabilization. The 10μm droplet dimension correlates with the jet radius and the instability wavelength, both determined from a simple scaling argument involving a viscous-capillary dominant force balance. The results are further supported by numerical solution of the evolution equation governing the interfacial profile of a sessile drop along which an acoustic pressure wave is imposed. Viscous and capillary forces dominate in the bulk of the parent drop, but inertia is dominant in the ejected jets and within a thin boundary layer adjacent to the substrate where surface and interfacial accelerations are large. With the specific exception of parent drops that spread into thin films with thicknesses on the order of the boundary layer dimension prior to atomization, the free surface of the drop is always observed to vibrate at the capillary-viscous resonance frequency—even if the exciting frequency of the surface acoustic wave is several orders of magnitude larger—contrary to

  12. Acoustically Generated Flow and Temperature Fields in a Rectangular Cavity

    NASA Astrophysics Data System (ADS)

    Farouk, Bakhtier; Oran, Elaine

    1998-11-01

    Flows induced by a vibrating transducer in a gas-filled two-dimensional cavity are investigated by solving the two-dimensional compressible Navier-Stokes equations. The transducer (driver) is located along the left vertical wall of the cavity whereas the right rigid wall acts as an acoustic reflector. Both the left and right vertical walls of the cavity are considered to be conducting (isothermal) walls. The top and the bottom walls are insulated. The frequency of the driver was varied between 10 and 500 kHz. The length of the cavity was adjusted such that standing waves are formed within the cavity, which in turn create well defined vortical flows (acoustic streaming. The characteristics of the two-dimensional acoustically generated flows are studied systematically by varying the frequency and amplitude of the motion of the transducer and the aspect ratio of the cavity. The result exhibit organized flow structures within the cavity and the existence of lateral temperature gradients. Such acoustically induced temperature gradients are essential in the operation of thermoacoustic engines and refrigerators. The effect of cooling or heating the reflector wall on the acoustically generated flows are also investigated. Long time solutions of the governing equations exhibit the existence of pseudo-steady oscillatory flow conditions.

  13. Numerical investigation of diffraction of acoustic waves by phononic crystals

    NASA Astrophysics Data System (ADS)

    Moiseyenko, Rayisa P.; Declercq, Nico F.; Laude, Vincent

    2012-05-01

    Diffraction as well as transmission of acoustic waves by two-dimensional phononic crystals (PCs) composed of steel rods in water are investigated in this paper. The finite element simulations were performed in order to compute pressure fields generated by a line source that are incident on a finite size PC. Such field maps are analyzed based on the complex band structure for the infinite periodic PC. Finite size computations indicate that the exponential decrease of the transmission at deaf frequencies is much stronger than that in Bragg band gaps.

  14. Magnetoelectric coupling by acoustic wave guide

    NASA Astrophysics Data System (ADS)

    Li, X. Y.; Liu, J.; Zhang, N.

    2016-04-01

    Magnetoelectric (ME) coupling by acoustic waveguide was developed. A very strong axial ME response was observed. The dependences of the sample size and the frequency of the ac field on the ME coupling were investigated. Several resonant points were observed in the frequency range applied (<50 kHz). Analysis shows that the standing waves transmitted in the waveguide were responsible for those resonances. And the resonant frequencies were closely influenced by the geometrical size of the waveguide. A resonant condition related to the size of the sample was obtained. The axial (or longitudinal) and transversal ME coefficients were observed to be up to 62 and 6 (V cm-1 Oe-1) at resonant points, respectively, indicating that the axial ME effect in this device was much higher than its transversal ones. A series of double-peak curves of axial ME coefficient versus magnetic field were observed. The significance of the double-peak curves was discussed.

  15. Ion-acoustic cnoidal waves in a quantum plasma

    SciTech Connect

    Mahmood, S.; Haas, F.

    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.

  16. Generation mechanism of terahertz coherent acoustic phonons in Fe

    NASA Astrophysics Data System (ADS)

    Henighan, T.; Trigo, M.; Bonetti, S.; Granitzka, P.; Higley, D.; Chen, Z.; Jiang, M. P.; Kukreja, R.; Gray, A.; Reid, A. H.; Jal, E.; Hoffmann, M. C.; Kozina, M.; Song, S.; Chollet, M.; Zhu, D.; Xu, P. F.; Jeong, J.; Carva, K.; Maldonado, P.; Oppeneer, P. M.; Samant, M. G.; Parkin, S. S. P.; Reis, D. A.; Dürr, H. A.

    2016-06-01

    We use femtosecond time-resolved hard x-ray scattering to detect coherent acoustic phonons generated during ultrafast laser excitation of ferromagnetic bcc Fe films grown on MgO(001). We observe the coherent longitudinal-acoustic phonons as a function of wave vector through analysis of the temporal oscillations in the x-ray scattering signal. The width of the extracted strain wave front associated with this coherent motion is ˜100 fs. An effective electronic Grüneisen parameter is extracted within a two-temperature model. However, ab initio calculations show that the phonons are nonthermal on the time scale of the experiment, which calls into question the validity of extracting physical constants by fitting such a two-temperature model.

  17. Activation of immobilized enzymes by acoustic wave resonance oscillation.

    PubMed

    Nishiyama, Hiroshi; Watanabe, Tomoya; Inoue, Yasunobu

    2014-12-01

    Acoustic wave resonance oscillation has been used successfully in the development of methods to activate immobilized enzyme catalysts. In this study, resonance oscillation effects were demonstrated for enzyme reactions on galactose oxidase (GAD), D-amino acid oxidase (DAAO), and L-amino acid oxidase (LAAO), all of which were immobilized covalently on a ferroelectric lead zirconate titanate (PZT) device that could generate thickness-extensional resonance oscillations (TERO) of acoustic waves. For galactose oxidation on immobilized GAD in a microreactor, TERO generation immediately increased enzyme activity 2- to 3-fold. Eliminating TERO caused a slight decrease in the activity, with ∼90% of the enhanced activity retained while the reaction proceeded. Contact of the enhanced enzyme with a galactose-free solution caused almost complete reversion of the activity to the original low level before TERO generation, indicating that, not only TERO-induced GAD activation, but also preservation of the increased activity, required a galactose substrate. Similar activity changes with TERO were observed for enzyme reactions on DAAO and LAAO. Kinetic analysis demonstrated that TERO helped strengthen the interactions of the immobilized enzyme with the reactant substrate and promoted formation of an activation complex. PMID:25442945

  18. Reverberant Acoustic Testing and Direct Field Acoustic Testing Acoustic Standing Waves and their Impact on Structural Responses

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu

    2012-01-01

    The aerospace industry has been using two methods of acoustic testing to qualify flight hardware: (1) Reverberant Acoustic Test (RAT), (2) Direct Field Acoustic Test (DFAT). The acoustic field obtained by RAT is generally understood and assumed to be diffuse, expect below Schroeder cut-of frequencies. DFAT method of testing has some distinct advantages over RAT, however the acoustic field characteristics can be strongly affected by test setup such as the speaker layouts, number and location of control microphones and control schemes. In this paper the following are discussed based on DEMO tests performed at APL and JPL: (1) Acoustic wave interference patterns and acoustic standing waves, (2) The structural responses in RAT and DFAT.

  19. Tissue differentiation using laser-induced shock waves by detection of acoustic transients through an optical wave-guide

    NASA Astrophysics Data System (ADS)

    Tschepe, Johannes; Ahrens, Thomas; Helfmann, Juergen; Mueller, Gerhard J.; Gapontsev, Valentin P.

    1993-05-01

    Some physical phenomena which occur during the fragmentation of calculi by laser induced optical break down are presented. With in vitro experiments it could be shown that the energy of the laser induced plasma and of the cavitation bubble (induced by the plasma) depends by the nature of the tissue. The laser induced plasma and the cavitation bubble generate shock waves. These sound waves are transferred via the laser fiber and detected with a piezo- electrical sensor at the proximal end. The acoustic signal contains information on the potential energy of the bubble, which depends on the energy of the plasma. The possibility of measuring the energy dependent acoustic transients allows to distinguish between hard and soft tissue and by this it is suitable for controlling the laser lithotripsy process. The transmission of acoustic transients through silica glass fibers is investigated by theoretical calculations. It shows the feasibility of silica glass fibers as an acoustic wave guide.

  20. Acoustic power absorption and enhancement generated by slow and fast MHD waves. Evidence of solar cycle velocity/intensity amplitude changes consistent with the mode conversion theory

    NASA Astrophysics Data System (ADS)

    Simoniello, R.; Finsterle, W.; García, R. A.; Salabert, D.; Jiménez, A.; Elsworth, Y.; Schunker, H.

    2010-06-01

    We used long duration, high quality, unresolved (Sun-as-a star) observations collected by the ground based network BiSON and by the instruments GOLF and VIRGO on board the ESA/NASA SOHO satellite to search for solar-cycle-related changes in mode characteristics in velocity and continuum intensity for the frequency range between 2.5 mHz <ν< 6.8 mHz. Over the ascending phase of solar cycle 23 we found a suppression in the p-mode amplitudes both in the velocity and intensity data between 2.5 mHz <ν< 4.5 mHz with a maximum suppression for frequencies in the range between 2.5 mHz <ν< 3.5 mHz. The size of the amplitude suppression is 13 ± 2 per cent for the velocity and 9 ± 2 per cent for the intensity observations. Over the range of 4.5 mHz <ν< 5.5 mHz the findings hint within the errors to a null change both in the velocity and intensity amplitudes. At still higher frequencies, in the so called High-frequency Interference Peaks (HIPs) between 5.8 mHz <ν< 6.8 mHz, we found an enhancement in the velocity amplitudes with the maximum 36 ± 7 per cent occurring for 6.3 mHz <ν< 6.8 mHz. However, in intensity observations we found a rather smaller enhancement of about 5 ± 2 per cent in the same interval. There is evidence that the frequency dependence of solar-cycle velocity amplitude changes is consistent with the theory behind the mode conversion of acoustic waves in a non-vertical magnetic field, but there are some problems with the intensity data, which may be due to the height in the solar atmosphere at which the VIRGO data are taken.

  1. Modeling of Conversion of Seismic to Acoustic Waves at the Seafloor Interface

    NASA Astrophysics Data System (ADS)

    Balanche, A.; Guennou, C.; Goslin, J.; Dziak, R.

    2007-12-01

    Hydroacoustic waves are generated at the seafloor interface, by conversion of seismic waves and travel in the water column within the SOFAR channel with little attenuation. Recording T-waves with widespread arrays of autonomous hydrophones moored in the SOFAR channel allows to detect and localize many small-magnitude earthquakes in oceanic areas. However, hydroacoustic data cannot be used straightforwardly in seismic interpretations. In particular, because the physics of the seismic to acoustic conversion and the acoustic propagation is not completely understood, no direct information on the event magnitudes, focal mechanisms and focal depths can be directly derived from the hydroacoustic signals. In order to overcome some of these limitations, we have developed a mechanical model of the conversion from seismic to acoustic waves at the seafloor interface. The modelling is achieved through major adaptations of the 2D- finite element code "FLUSOL", which was originally developed to model fluid to solid energy conversion. Velocity displacement module within fluids and solids are derived from the stress and pressure computed for each grid element. We are able to model successfully, over a 10 x 10 km-grid, the seismic to acoustic conversion of waves generated by a source in the crust. Our model shows that a source with a high S-wave content appear to be more efficient in producing T-waves than a simple explosive source that only generates P-waves. Future work include the modelling of the conversion by more realistic seafloor topographies. Finally, we will use the output of SOLFLU as input to standard long-range acoustic propagation codes made available by the marine acoustics community. The modelled T-waves generated by various source mechanisms (tectonic or magmatic) will then be compared with real data to validate our conversion model.

  2. Controlling acoustic-wave propagation through material anisotropy

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  4. Relationship between dust acoustic waves in two and three dimensions

    SciTech Connect

    Piel, A.; Goree, J.

    2006-10-15

    Low frequency electrostatic waves are investigated for a monolayer suspension of dust particles that are shielded by an ambient plasma of three-dimensional extension. The dispersion of the resulting dust acoustic surface waves is compared with dust acoustic waves in three dimensions and with lattice modes in two dimensions. It is found that the wave dispersion is determined by shielding of electric fields by electrons and ions on either side of the dust monolayer; this differs from previously studied cases of charged sheets in a vacuum. The phase velocity of these surface waves suggests the definition of a proper dust plasma frequency for monolayer systems.

  5. Relationship between dust acoustic waves in two and three dimensions

    NASA Astrophysics Data System (ADS)

    Piel, A.; Goree, J.

    2006-10-01

    Low frequency electrostatic waves are investigated for a monolayer suspension of dust particles that are shielded by an ambient plasma of three-dimensional extension. The dispersion of the resulting dust acoustic surface waves is compared with dust acoustic waves in three dimensions and with lattice modes in two dimensions. It is found that the wave dispersion is determined by shielding of electric fields by electrons and ions on either side of the dust monolayer; this differs from previously studied cases of charged sheets in a vacuum. The phase velocity of these surface waves suggests the definition of a proper dust plasma frequency for monolayer systems.

  6. Ultrafast microfluidics using surface acoustic waves

    PubMed Central

    Yeo, Leslie Y.; Friend, James R.

    2009-01-01

    We demonstrate that surface acoustic waves (SAWs), nanometer amplitude Rayleigh waves driven at megahertz order frequencies propagating on the surface of a piezoelectric substrate, offer a powerful method for driving a host of extremely fast microfluidic actuation and micro∕bioparticle manipulation schemes. We show that sessile drops can be translated rapidly on planar substrates or fluid can be pumped through microchannels at 1–10 cm∕s velocities, which are typically one to two orders quicker than that afforded by current microfluidic technologies. Through symmetry-breaking, azimuthal recirculation can be induced within the drop to drive strong inertial microcentrifugation for micromixing and particle concentration or separation. Similar micromixing strategies can be induced in the same microchannel in which fluid is pumped with the SAW by merely changing the SAW frequency to rapidly switch the uniform through-flow into a chaotic oscillatory flow by exploiting superpositioning of the irradiated sound waves from the sidewalls of the microchannel. If the flow is sufficiently quiescent, the nodes of the transverse standing wave that arises across the microchannel also allow for particle aggregation, and hence, sorting on nodal lines. In addition, the SAW also facilitates other microfluidic capabilities. For example, capillary waves excited at the free surface of a sessile drop by the SAW underneath it can be exploited for micro∕nanoparticle collection and sorting at nodal points or lines at low powers. At higher powers, the large accelerations off the substrate surface as the SAW propagates across drives rapid destabilization of the drop free surface giving rise to inertial liquid jets that persist over 1–2 cm in length or atomization of the entire drop to produce 1–10 μm monodispersed aerosol droplets, which can be exploited for ink-jet printing, mass spectrometry interfacing, or pulmonary drug delivery. The atomization of polymer∕protein solutions

  7. Waveform inversion of acoustic waves for explosion yield estimation

    NASA Astrophysics Data System (ADS)

    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 (<10 km) and provided reasonable yield estimates (<˜30% error) in the presence of realistic topography and atmospheric structure. The presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.

  8. False Paradoxes of Superposition in Electric and Acoustic Waves.

    ERIC Educational Resources Information Center

    Levine, Richard C.

    1980-01-01

    Corrected are several misconceptions concerning the apparently "missing" energy that results when acoustic or electromagnetic waves cancel by destructive interference and the wave impedance reflected to the sources of the wave energy changes so that the input power is reduced. (Author/CS)

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

    PubMed

    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

  10. MODE CONVERSION BETWEEN DIFFERENT RADIAL ORDERS FOR SOLAR ACOUSTIC WAVES SCATTERED BY SUNSPOTS

    SciTech Connect

    Zhao, Hui; Chou, Dean-Yi

    2013-11-20

    We study the mode conversion between different radial orders for solar acoustic waves interacting with sunspots. Solar acoustic waves are modified in the presence of sunspots. The modification in the wave can be viewed as that the sunspot, excited by the incident wave, generates the scattered wave, and the scattered wave is added to the incident wave to form the total wave inside and around the sunspot. The wavefunction of the acoustic wave on the solar surface is computed from the cross-correlation function. The wavefunction of the scattered wave is obtained by subtracting the wavefunction of the incident wave from that of the total wave. We use the incident waves of radial order n = 0-5 to measure the scattered wavefunctions from n to another radial order n' for NOAAs 11084 and 11092. The strength of scattered waves decreases rapidly with |Δn|, where Δn ≡ n' – n. The scattered waves of Δn = ±1 are visible for n ≤ 1, and significant for n ≥ 2. For the scattered wave of Δn = ±2, only few cases are visible. None of the scattered waves of Δn = ±3 are visible. The properties of scattered waves for Δn = 0 and Δn ≠ 0 are different. The scattered wave amplitude relative to the incident wave amplitude decreases with n for Δn = 0, while it increases with n for Δn ≠ 0. The scattered wave amplitudes of Δn = 0 are greater for the larger sunspot, while those of Δn ≠ 0 are insensitive to the sunspot size.

  11. Generation and development of small-amplitude disturbances in a laminar boundary layer in the presence of an acoustic field

    NASA Technical Reports Server (NTRS)

    Kachanov, Y. S.; Kozlov, V. V.; Levchenko, V. Y.

    1985-01-01

    A low-turbulence subsonic wind tunnel was used to study the influence of acoustic disturbances on the development of small sinusoidal oscillations (Tollmien-Schlichting waves) which constitute the initial phase of turbulent transition. It is found that acoustic waves propagating opposite to the flow generate vibrations of the model (plate) in the flow. Neither the plate vibrations nor the acoustic field itself have any appreciable influence on the stability of the laminar boundary layer. The influence of an acoustic field on laminar boundary layer disturbances is limited to the generation of Tollmien-Schlichting waves at the leading-edge of the plate.

  12. Reducing extrinsic damping of surface acoustic waves at gigahertz frequencies

    NASA Astrophysics Data System (ADS)

    Gelda, Dhruv; Sadhu, Jyothi; Ghossoub, Marc G.; Ertekin, Elif; Sinha, Sanjiv

    2016-04-01

    High-frequency surface acoustic waves (SAWs) in the gigahertz range can be generated using absorption from an ultrafast laser in a patterned metallic grating on a substrate. Reducing the attenuation at these frequencies can yield better sensors as well as enable them to better probe phonon and electron-phonon interactions near surfaces. It is not clear from existing experiments which mechanisms dominate damping at high frequencies. We calculate damping times of SAWs due to various mechanisms in the 1-100 GHz range to find that mechanical loading of the grating on the substrate dominates dissipation by radiating energy from the surface into the bulk. To overcome this and enable future measurements to probe intrinsic damping, we propose incorporating distributed acoustic Bragg reflectors in the experimental structure. Layers of alternating materials with contrasting acoustic impedances embedded a wavelength away from the surface serve to reflect energy back to the surface. Using numerical simulations, we show that a single Bragg reflector is sufficient to increase the energy density at the surface by more than five times. We quantify the resulting damping time to find that it is longer than the intrinsic damping time. The proposed structure can enable future measurements of intrinsic damping in SAWs at ˜100 GHz.

  13. Diaphragm Pressure Wave Generator Developments at Industrial Research Ltd

    NASA Astrophysics Data System (ADS)

    Caughley, A. J.; Emery, N.; Glasson, N. D.

    2010-04-01

    Industrial Research Ltd (IRL) have been developing a unique diaphragm based pressure wave generator technology for pulse tube and Stirling cryocoolers. Our system uses a metal diaphragm to separate the clean cryocooler gas circuit from a conventionally lubricated mechanical driver, thus producing a clean pressure wave with a long life drive that does not require the precision manufacture and associated costs of large linear motors. The first successful diaphragm pressure wave generator produced 3.2 kW of acoustic power at an electro-acoustic efficiency of 72% with a swept volume of 200 ml and a prototype has now accumulated over 2500 hours running. This paper describes recent developments in the technology. To explore scaling, a small diaphragm pressure wave generator with a swept volume of 20 ml has been constructed and has delivered 454 W of acoustic power at an electro-acoustic efficiency of 60%. Improvements have been made to the hydraulic force amplifier mechanism for driving the diaphragms resulting in a cheaper and lighter mechanism than the mechanical linkage originally used. To meet a customer's specific requirements, the 200 ml pressure wave generator's stroke was extended to achieve 240 ml of swept volume thereby increasing its acoustic power delivery to 4.1 kW without compromising efficiency.

  14. Characterization of energy trapping in a bulk acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    Kokkonen, Kimmo; Meltaus, Johanna; Pensala, Tuomas; Kaivola, Matti

    2010-12-01

    Acoustic wave fields both within the active electrode area of a solidly mounted 1.8 GHz bulk acoustic wave resonator, and around it in the surrounding region, are measured using a heterodyne laser interferometer. Plate-wave dispersion diagrams for both regions are extracted from the measurement data. The experimental dispersion data reveal the cutoff frequencies of the acoustic vibration modes in the region surrounding the resonator, and, therefore, the energy trapping range of the resonator can readily be determined. The measured dispersion properties of the surrounding region, together with the abruptly diminishing amplitude of the dispersion curves in the resonator, signal the onset of acoustic leakage from the resonator. This information is important for verifying and further developing the simulation tools used for the design of the resonators. Experimental wave field images, dispersion diagrams for both regions, and the threshold for energy leakage are discussed.

  15. Charging-delay induced dust acoustic collisionless shock wave: Roles of negative ions

    SciTech Connect

    Ghosh, Samiran; Bharuthram, R.; Khan, Manoranjan; Gupta, M. R.

    2006-11-15

    The effects of charging-delay and negative ions on nonlinear dust acoustic waves are investigated. It has been found that the charging-delay induced anomalous dissipation causes generation of dust acoustic collisionless shock waves in an electronegative dusty plasma. The small but finite amplitude wave is governed by a Korteweg-de Vries Burger equation in which the Burger term arises due to the charging-delay. Numerical investigations reveal that the charging-delay induced dissipation and shock strength decreases (increases) with the increase of negative ion concentration (temperature)

  16. Estimating propagation velocity through a surface acoustic wave sensor

    DOEpatents

    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.

  17. Spectral solution of acoustic wave-propagation problems

    NASA Technical Reports Server (NTRS)

    Kopriva, David A.

    1990-01-01

    The Chebyshev spectral collocation solution of acoustic wave propagation problems is considered. It is shown that the phase errors decay exponentially fast and that the number of points per wavelength is not sufficient to estimate the phase accuracy. Applications include linear propagation of a sinusoidal acoustic wavetrain in two space dimensions, and the interaction of a sound wave with the bow shock formed by placing a cylinder in a uniform Mach 4 supersonic free stream.

  18. Surface acoustic wave devices for sensor applications

    NASA Astrophysics Data System (ADS)

    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).

  19. Surface Acoustic Wave (SAW) Vibration Sensors

    PubMed Central

    Filipiak, Jerzy; Solarz, Lech; Steczko, Grzegorz

    2011-01-01

    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. PMID:22247694

  20. Surface acoustic wave (SAW) vibration sensors.

    PubMed

    Filipiak, Jerzy; Solarz, Lech; Steczko, Grzegorz

    2011-01-01

    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. PMID:22247694

  1. Transport Powder and Liquid Samples by Surface Acoustic Waves

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Louyeh, Sahar

    2009-01-01

    Sample transport is an important requirement for In-situ analysis of samples in NASA planetary exploration missions. Tests have shown that powders or liquid drops on a surface can be transported by surface acoustic waves (SAW) that are generated on the surface using interdigital transducers. The phenomena were investigated experimentally and to generate SAWs interdigital electrodes were deposited on wafers of 128 deg rotated Y-cut LiNbO?. Transporting capability of the SAW device was tested using particles of various sizes and drops of various viscosities liquids. Because of different interaction mechanisms with the SAWs, the powders and the liquid drops were observed to move in opposite directions. In the preliminary tests, a speed of 180 mm/s was achieved for powder transportation. The detailed experimental setup and results are presented in this paper. The transporting mechanism can potentially be applied to miniaturize sample analysis system or " lab-on-chip" devices.

  2. Tunable Nanowire Patterning Using Standing Surface Acoustic Waves

    PubMed Central

    Chen, Yuchao; Ding, Xiaoyun; Lin, Sz-Chin Steven; Yang, Shikuan; Huang, Po-Hsun; Nama, Nitesh; Zhao, Yanhui; Nawaz, Ahmad Ahsan; Guo, Feng; Wang, Wei; Gu, Yeyi; Mallouk, Thomas E.; Huang, Tony Jun

    2014-01-01

    Patterning of nanowires in a controllable, tunable manner is important for the fabrication of functional nanodevices. Here we present a simple approach for tunable nanowire patterning using standing surface acoustic waves (SSAW). This technique allows for the construction of large-scale nanowire arrays with well-controlled patterning geometry and spacing within 5 seconds. In this approach, SSAWs were generated by interdigital transducers (IDTs), which induced a periodic alternating current (AC) electric field on the piezoelectric substrate and consequently patterned metallic nanowires in suspension. The patterns could be deposited onto the substrate after the liquid evaporated. By controlling the distribution of the SSAW field, metallic nanowires were assembled into different patterns including parallel and perpendicular arrays. The spacing of the nanowire arrays could be tuned by controlling the frequency of the surface acoustic waves. Additionally, we observed 3D spark-shape nanowire patterns in the SSAW field. The SSAW-based nanowire-patterning technique presented here possesses several advantages over alternative patterning approaches, including high versatility, tunability, and efficiency, making it promising for device applications. PMID:23540330

  3. Tunable nanowire patterning using standing surface acoustic waves.

    PubMed

    Chen, Yuchao; Ding, Xiaoyun; Steven Lin, Sz-Chin; Yang, Shikuan; Huang, Po-Hsun; Nama, Nitesh; Zhao, Yanhui; Nawaz, Ahmad Ahsan; Guo, Feng; Wang, Wei; Gu, Yeyi; Mallouk, Thomas E; Huang, Tony Jun

    2013-04-23

    Patterning of nanowires in a controllable, tunable manner is important for the fabrication of functional nanodevices. Here we present a simple approach for tunable nanowire patterning using standing surface acoustic waves (SSAW). This technique allows for the construction of large-scale nanowire arrays with well-controlled patterning geometry and spacing within 5 s. In this approach, SSAWs were generated by interdigital transducers, which induced a periodic alternating current (ac) electric field on the piezoelectric substrate and consequently patterned metallic nanowires in suspension. The patterns could be deposited onto the substrate after the liquid evaporated. By controlling the distribution of the SSAW field, metallic nanowires were assembled into different patterns including parallel and perpendicular arrays. The spacing of the nanowire arrays could be tuned by controlling the frequency of the surface acoustic waves. Additionally, we observed 3D spark-shaped nanowire patterns in the SSAW field. The SSAW-based nanowire-patterning technique presented here possesses several advantages over alternative patterning approaches, including high versatility, tunability, and efficiency, making it promising for device applications. PMID:23540330

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

    NASA Astrophysics Data System (ADS)

    Tian, Miao; Kadri, Usama

    2016-04-01

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

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

    NASA Technical Reports Server (NTRS)

    Davis, Sanford

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  7. Using time-reversal to generate generalized transversely localized transient waves (X-waves).

    PubMed

    Walker, S C

    2009-03-01

    In the traditional approach to X-waves, the X-wave field is synthesized from a superposition of solutions to the homogenous wave equation (in three-dimensions) without regard to boundary conditions. As a consequence the synthesized solution is acausal. Here, it is shown that the solution to the inhomogenous scalar wave equation for the acoustic field from a supersonic source distribution consistent with the radiation condition, i.e., a Mach front, defines a causal X-wave. Using the connection between X-waves and a physical source, it is shown that an X-wave can be generated from a planar aperture using time-reversal. By appealing to the demonstrated self-adaptivity of time-reversal processes, the method should allow for the generation of X-waves in arbitrary (inhomogenous) media. Typically, the generation of approximate acoustic X-waves from a planar aperture is achieved using a complicated annular transducer arrangement. Here, the time-reversal method for the generation of approximate acoustic X-waves is experimentally proven using a line transducer array in two-dimensional geometry in free space. PMID:19275313

  8. Acoustic waves in a stratified atmosphere. IV. Three-dimensional nonlinear hydrodynamics

    NASA Astrophysics Data System (ADS)

    Kalkofen, W.; Rossi, P.; Bodo, G.; Massaglia, S.

    2010-09-01

    Context. The quiet solar chromosphere in the interior of supergranulation cells is believed to be heated by the dissipation of acoustic waves that originate with a typical period of 3 min in the photosphere. Aims: We investigate how the horizontal expansion with height of acoustic waves traveling upward into an isothermal, gravitationally stratified atmosphere depends on the size of the source region. Methods: We have solved the three-dimensional, nonlinear, time-dependent hydrodynamic equations for impulsively-generated, upward-propagating acoustic waves, assuming cylindrical symmetry. Results: When the diameter of the source of acoustic waves is small, the pattern of the upward-propagating waves is that of a point source, for which the energy travels upward in a vertical cone, qualitatively matching the observed pattern of bright-point expansion with height. For the largest plausible size of a source region, i.e., with granular size of 1 Mm, wave propagation in the low chromosphere is approximately that of plane waves, but in the middle and upper chromosphere it is also that of a point source. The assumption of plane-wave propagation is not a good approximation in the solar chromosphere. The upward-directed energy flux is larger than that of the solar chromosphere, at least in the middle and upper chromosphere, and probably throughout. Conclusions: Simulations of impulsively generated acoustic waves emitted from source regions with diameters that are small compared to the pressure scale height of the atmosphere qualitatively reproduce the upward expansion observed in chromospheric bright points. The emission features in the cores of the H and K lines are predicted to be blueshifted for a pulse and redshifted for the waves in its wake. The contribution of internal gravity waves to the upward energy flux is small and decreases with increasing size of the source region.

  9. Acoustic waves in gases with strong pressure gradients

    NASA Technical Reports Server (NTRS)

    Zorumski, William E.

    1989-01-01

    The effect of strong pressure gradients on the acoustic modes (standing waves) of a rectangular cavity is investigated analytically. When the cavity response is represented by a sum of modes, each mode is found to have two resonant frequencies. The lower frequency is near the Viaesaela-Brundt frequency, which characterizes the buoyant effect, and the higher frequency is above the ordinary acoustic resonance frequency. This finding shows that the propagation velocity of the acoustic waves is increased due to the pressure gradient effect.

  10. Ion Acoustic Waves, A High School Plasma Experiment

    NASA Astrophysics Data System (ADS)

    Buck, R.; Wise, J.; Gibson, N.; Buck, M.; Gekelman, W.; Wetzel, E.; Wetzel, C.; Moynihan, C.

    2001-10-01

    Over the last three the Los Angeles Physics Teachers Alliance Group (LAPTAG) has built a plasma device and designed experiments for high school students to learn about plasma properties and behavior. One of the first experiments performed by small student groups (two to three students at a time) is to create ion acoustic wave tonebursts in an Argon plasma, measure the wavelength and frequency of the wave and thereby calculate the velocity of the wave. A grid antenna immersed in the plasma, which is pulsed by a function generator, creates the waves. Measurements are made using a Langmuir probe and read out on a digital oscilloscope. From this information students calculate values such as the temperature of the plasma, the plasma density and percent ionization of the plasma. In order to do these experiments students must understand what plasma is, how plasma can be created using a helicon source, how to use an oscilloscope and many other aspects of the plasma chamber involved in the experiment. Other experiments are currently being done on the device and still others are being designed. For more information visit the LAPTAG website (http://coke.physics.ucla.edu/laptag).

  11. Multiple-frequency acoustic wave devices for chemical sensing and materials characterization in both gas and liquid phase

    DOEpatents

    Martin, S.J.; Ricco, A.J.

    1993-08-10

    A chemical or intrinsic physical property sensor is described comprising: (a) a substrate; (b) an interaction region of said substrate where the presence of a chemical or physical stimulus causes a detectable change in the velocity and/or an attenuation of an acoustic wave traversing said region; and (c) a plurality of paired input and output interdigitated electrodes patterned on the surface of said substrate where each of said paired electrodes has a distinct periodicity, where each of said paired electrodes is comprised of an input and an output electrode; (d) an input signal generation means for transmitting an input signal having a distinct frequency to a specified input interdigitated electrode of said plurality so that each input electrode receives a unique input signal, whereby said electrode responds to said input signal by generating an acoustic wave of a specified frequency, thus, said plurality responds by generating a plurality of acoustic waves of different frequencies; (e) an output signal receiving means for determining an acoustic wave velocity and an amplitude of said acoustic waves at several frequencies after said waves transverses said interaction region and comparing these values to an input acoustic wave velocity and an input acoustic wave amplitude to produce values for perturbations in acoustic wave velocities and for acoustic wave attenuation as a function of frequency, where said output receiving means is individually coupled to each of said output interdigitated electrode; (f) a computer means for analyzing a data stream comprising information from said output receiving means and from said input signal generation means to differentiate a specified response due to a perturbation from a subsequent specified response due to a subsequent perturbation to determine the chemical or intrinsic physical properties desired.

  12. Cascading processes in the nonlinear diffraction of light by standing acoustic waves

    NASA Astrophysics Data System (ADS)

    Dadoenkova, Yu. S.; Dadoenkova, N. N.; Bentivegna, F. F. L.; Lyubchanskii, I. L.; Lee, Y. P.

    2016-01-01

    The contribution of two types of cascading process to the nonlinear optical diffraction of electromagnetic waves from a standing acoustic wave in a GaAs crystal is theoretically studied. The first type of cascading process results from second-harmonic generation followed by linear acousto-optical diffraction, while the second type involves linear acousto-optical diffraction from the standing acoustic wave and subsequent sum-frequency generation. In contrast to the third, direct, nonlinear acousto-optical diffraction process we previously investigated, the photoelastic interaction between electromagnetic and acoustic waves is here linear. We establish the rules governing the cascading processes and show that in most cases the output signal simultaneously results from two or even three of the possible nonlinear diffraction mechanisms. However, we demonstrate that a careful choice of the incidence angles of the incoming electromagnetic waves, of the polarization combinations of the incoming and diffracted waves, and of the type of acoustic wave (longitudinal or transverse) makes it always possible to distinguish between the direct and either of the two cascading processes.

  13. A standing-wave flow measurement system for small diameter pipes using long acoustic waves

    NASA Astrophysics Data System (ADS)

    Ikpe, E. S.; Scarrott, G.; Weight, J. P.; Grattan, K. T. V.

    1993-09-01

    An exploratory investigation, using laboratory fabricated acoustic components, of standing-wave flow measurement techniques for liquids and gases in pipes of diameter up to about 25 mm was undertaken, using long acoustic waves. The results show a linear sensitivity based on the ``sing-around'' technique, often associated with contrapropagating time-of-flight flowmeters. A repeatability test at a volume flow rate of 1.5 l per minute indicates that, within the 95% confidence limit, only 5% of the readings will lie outside the range of 1.1-1.9 l per minute. The transducer used in the above investigation comprises a section of the pipe wall which acts as part of a resonating transmitter or detector of long waves in a fluid. The measurement cell is closed and generates a known standing-wave pattern. The results obtained suggest that, in the future, the initial accuracy obtained in this study can be significantly enhanced with further improvements to the transducers, the measurement cell, the electronics, and test procedures, on which work is continuing, to produce a device competitive with those using other technologies.

  14. Generation of acoustic self-bending and bottle beams by phase engineering

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Li, Tongcang; Zhu, Jie; Zhu, Xuefeng; Yang, Sui; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

    2014-07-01

    Directing acoustic waves along curved paths is critical for applications such as ultrasound imaging, surgery and acoustic cloaking. Metamaterials can direct waves by spatially varying the material properties through which the wave propagates. However, this approach is not always feasible, particularly for acoustic applications. Here we demonstrate the generation of acoustic bottle beams in homogeneous space without using metamaterials. Instead, the sound energy flows through a three-dimensional curved shell in air leaving a close-to-zero pressure region in the middle, exhibiting the capability of circumventing obstacles. By designing the initial phase, we develop a general recipe for creating self-bending wave packets, which can set acoustic beams propagating along arbitrary prescribed convex trajectories. The measured acoustic pulling force experienced by a rigid ball placed inside such a beam confirms the pressure field of the bottle. The demonstrated acoustic bottle and self-bending beams have potential applications in medical ultrasound imaging, therapeutic ultrasound, as well as acoustic levitations and isolations.

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

    NASA Astrophysics Data System (ADS)

    Chitta, Subhashini; Steinhoff, John

    2015-11-01

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

  16. Reconstructing surface wave profiles from reflected acoustic pulses using multiple receivers.

    PubMed

    Walstead, Sean P; Deane, Grant B

    2014-08-01

    Surface wave shapes are determined by analyzing underwater reflected acoustic signals collected at multiple receivers. The transmitted signals are of nominal frequency 300 kHz and are reflected off surface gravity waves that are paddle-generated in a wave tank. An inverse processing algorithm reconstructs 50 surface wave shapes over a length span of 2.10 m. The inverse scheme uses a broadband forward scattering model based on Kirchhoff's diffraction formula to determine wave shapes. The surface reconstruction algorithm is self-starting in that source and receiver geometry and initial estimates of wave shape are determined from the same acoustic signals used in the inverse processing. A high speed camera provides ground-truth measurements of the surface wave field for comparison with the acoustically derived surface waves. Within Fresnel zone regions the statistical confidence of the inversely optimized surface profile exceeds that of the camera profile. Reconstructed surfaces are accurate to a resolution of about a quarter-wavelength of the acoustic pulse only within Fresnel zones associated with each source and receiver pair. Multiple isolated Fresnel zones from multiple receivers extend the spatial extent of accurate surface reconstruction while overlapping Fresnel zones increase confidence in the optimized profiles there. PMID:25096095

  17. Application of surface acoustic wave devices to radio telemetry

    NASA Technical Reports Server (NTRS)

    Strasilla, U.

    1983-01-01

    Three experimental Surface Acoustic Wave Resonators (SAWR) are developed and evaluated. A desired center frequency is obtained by correct spacing of the Inter-Digital Transducers (IDT). Transmitting and receiving IDT's must be close for adequate coupling and a sufficient number of reflectors are required to create a high quality standing wave. A review of oscillator theory is given and current technology evaluated.

  18. Quantum ion-acoustic wave oscillations in metallic nanowires

    SciTech Connect

    Moradi, Afshin

    2015-05-15

    The low-frequency electrostatic waves in metallic nanowires are studied using the quantum hydrodynamic model, in which the electron and ion components of the system are regarded as a two-species quantum plasma system. The Poisson equation as well as appropriate quantum boundary conditions give the analytical expressions of dispersion relations of the surface and bulk quantum ion-acoustic wave oscillations.

  19. Observation of the coupling of the driven dust acoustic wave

    SciTech Connect

    Williams, Jeremiah D.; Duff, James

    2010-03-15

    In this study, the coupling between the naturally occurring dust acoustic wave (DAW) and the discharge current modulation is examined. It is confirmed that, when the wave is driven by modulating the discharge current, the DAW is driven at the same frequency as the current modulation.

  20. Surface wave patterns on acoustically levitated viscous liquid alloys

    NASA Astrophysics Data System (ADS)

    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.

  1. Enhancement of Focused Ultrasound Treatment by Acoustically Generated Microbubbles

    NASA Astrophysics Data System (ADS)

    Umemura, Shin-ichiro; Yoshizawa, Shin; Takagi, Ryo; Inaba, Yuta; Yasuda, Jun

    2013-07-01

    Microbubbles, whether introduced from outside the body or ultrasonically generated in situ, are known to significantly enhance the biological effects of ultrasound, including the mechanical, thermal, and sonochemical effects. Phase-change nanodroplets, which selectively accumulate in tumor tissue and whose phase changes to microbubbles can be induced by ultrasonic stimulation, have been proposed for high-intensity focused ultrasound (HIFU) tumor treatment with enhanced selectivity and efficiency. In this paper, a purely acoustic approach to generate microbubble clouds in the tissue to be treated is proposed. Short pulses of focused ultrasound with extremely high intensity, named trigger pulses, are used for exposure. They are immediately followed by focused ultrasound for heating with an intensity similar to or less than that of normal HIFU treatment. The localized generation of microbubble clouds by the trigger pulses is observed in a polyarylamide gel by a high-speed camera, and the effectiveness of the generated clouds in accelerating ultrasonically induced thermal coagulation is confirmed in excised chicken breast tissue. The use of second-harmonic superimposed waves as the trigger pulses is also proposed. The highly reproducible initiation of cavitation by waves with the negative peak pressure emphasized and the efficient expansion of the generated microbubble clouds by waves with the positive peak pressure emphasized are also observed by a high-speed camera in partially degassed water.

  2. Linear and nonlinear acoustic wave propagation in the atmosphere

    NASA Technical Reports Server (NTRS)

    Hariharan, S. I.; Yu, Ping

    1988-01-01

    The investigation of the acoustic wave propagation theory and numerical implementation for the situation of an isothermal atmosphere is described. A one-dimensional model to validate an asymptotic theory and a 3-D situation to relate to a realistic situation are considered. In addition, nonlinear wave propagation and the numerical treatment are included. It is known that the gravitational effects play a crucial role in the low frequency acoustic wave propagation. They propagate large distances and, as such, the numerical treatment of those problems become difficult in terms of posing boundary conditions which are valid for all frequencies.

  3. Fabrication of new Interdigital Transducers for Surface Acoustic Wave Device

    NASA Astrophysics Data System (ADS)

    Fissi, L. El; Jaouad, A.; Vandormael, D.; Francis, L. A.

    We investigate high-performance interdigital transducers (IDTs) for the generation of surface acoustic waves (SAWs) on AT-cut quartz, where the metal fingers are embedded in the substrate. Three micromachining techniques are used to manufacture SAW structures, namely an inductively coupled plasma, a laser etching and a reactive ion etching. An evaporated layer of Al and a Ni thick electroplating are used to grow the metals in the micromachining structures. A chemical mechanical polishing (CMP) technique is used to remove the exceeding metal and keep a flat surface. The electrical characterizations indicate that the fabricated devices are suited for sensing proposes with a low insertion loss and a linear phase. Results are reported emphasizing the efficiency of the Ni damascene process to manufacture SAW sensors with the embedded structures.

  4. Acoustic Shielding by Cavitation Bubbles in Shock Wave Lithotripsy (SWL)

    NASA Astrophysics Data System (ADS)

    Pishchalnikov, Yuri A.; McAteer, James A.; Bailey, Michael R.; Pishchalnikova, Irina V.; Williams, James C.; Evan, Andrew P.

    2006-05-01

    Lithotripter pulses (˜7-10 μs) initiate the growth of cavitation bubbles, which collapse hundreds of microseconds later. Since the bubble growth-collapse cycle trails passage of the pulse, and is ˜1000 times shorter than the pulse interval at clinically relevant firing rates, it is not expected that cavitation will affect pulse propagation. However, pressure measurements with a fiber-optic hydrophone (FOPH-500) indicate that bubbles generated by a pulse can, indeed, shield the propagation of the negative tail. Shielding was detected within 1 μs of arrival of the negative wave, contemporaneous with the first observation of expanding bubbles by high-speed camera. Reduced negative pressure was observed at 2 Hz compared to 0.5 Hz firing rate, and in water with a higher content of dissolved gas. We propose that shielding of the negative tail can be attributed to loss of acoustic energy into the expansion of cavitation bubbles.

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

    NASA Astrophysics Data System (ADS)

    Tabrizian, R.; Ayazi, F.

    2015-06-01

    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. Nonlinear electron-acoustic waves in quantum plasma

    SciTech Connect

    Sah, O. P.; Manta, J.

    2009-03-15

    The nonlinear wave structure of electron-acoustic waves (EAWs) is investigated in a three component unmagnetized dense quantum plasma consisting of two distinct groups of electrons (one inertial cold electron, and other inertialess hot electrons) and immobile ions. By employing one dimensional quantum hydrodynamic model and standard reductive perturbation technique, a Korteweg-de-Vries equation governing the dynamics of EAWs is derived. Both compressive and rarefactive solitons along with periodical potential structures are found to exist for various ranges of dimensionless quantum parameter H. The quantum mechanical effects are also examined numerically on the profiles of the amplitude and the width of electron-acoustic solitary waves. It is observed that both the amplitude and the width of electron-acoustic solitary waves are significantly affected by the parameter H. The relevance of the present investigation to the astrophysical ultradense plasmas is also discussed.

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

    SciTech Connect

    Tabrizian, R.; Ayazi, F.

    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.

  8. Broadband enhanced transmission of acoustic waves through serrated metal gratings

    NASA Astrophysics Data System (ADS)

    Qi, Dong-Xiang; Fan, Ren-Hao; Deng, Yu-Qiang; Peng, Ru-Wen; Wang, Mu; Jiangnan University Collaboration

    In this talk, we present our studies on broadband properties of acoustic waves through metal gratings. We have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing and new acoustic devices. References: [1] Dong-Xiang Qi, Yu-Qiang Deng, Di-Hu Xu, Ren-Hao Fan, Ru-Wen Peng, Ze-Guo Chen, Ming-Hui Lu, X. R. Huang and Mu Wang, Appl. Phys. Lett. 106, 011906 (2015); [2] Dong-Xiang Qi, Ren-Hao Fan, Ru-Wen Peng, Xian-Rong Huang, Ming-Hui Lu, Xu Ni, Qing Hu, and Mu Wang, Applied Physics Letters 101, 061912 (2012).

  9. Radial Shock Wave Devices Generate Cavitation

    PubMed Central

    Császár, Nikolaus B. M.; Angstman, Nicholas B.; Milz, Stefan; Sprecher, Christoph M.; Kobel, Philippe; Farhat, Mohamed; Furia, John P.; Schmitz, Christoph

    2015-01-01

    Background Conflicting reports in the literature have raised the question whether radial extracorporeal shock wave therapy (rESWT) devices and vibrating massage devices have similar energy signatures and, hence, cause similar bioeffects in treated tissues. Methods and Findings We used laser fiber optic probe hydrophone (FOPH) measurements, high-speed imaging and x-ray film analysis to compare fundamental elements of the energy signatures of two rESWT devices (Swiss DolorClast; Electro Medical Systems, Nyon, Switzerland; D-Actor 200; Storz Medical, Tägerwillen, Switzerland) and a vibrating massage device (Vibracare; G5/General Physiotherapy, Inc., Earth City, MO, USA). To assert potential bioeffects of these treatment modalities we investigated the influence of rESWT and vibrating massage devices on locomotion ability of Caenorhabditis elegans (C. elegans) worms. Results FOPH measurements demonstrated that both rESWT devices generated acoustic waves with comparable pressure and energy flux density. Furthermore, both rESWT devices generated cavitation as evidenced by high-speed imaging and caused mechanical damage on the surface of x-ray film. The vibrating massage device did not show any of these characteristics. Moreover, locomotion ability of C. elegans was statistically significantly impaired after exposure to radial extracorporeal shock waves but was unaffected after exposure of worms to the vibrating massage device. Conclusions The results of the present study indicate that both energy signature and bioeffects of rESWT devices are fundamentally different from those of vibrating massage devices. Clinical Relevance Prior ESWT studies have shown that tissues treated with sufficient quantities of acoustic sound waves undergo cavitation build-up, mechanotransduction, and ultimately, a biological alteration that “kick-starts” the healing response. Due to their different treatment indications and contra-indications rESWT devices cannot be equated to vibrating

  10. Spatial selective manipulation of microbubbles by tunable surface acoustic waves

    PubMed Central

    Zhou, Wei; Niu, Lili; Cai, Feiyan; Li, Fei; Wang, Chen; Huang, Xiaowei; Wang, Jingjing; Wu, Junru; Meng, Long; Zheng, Hairong

    2016-01-01

    A microfluidic device based on a pair of slant-finger interdigital transducers (SFITs) is developed to achieve a selective and flexible manipulation of microbubbles (MBs) by surface acoustic waves (SAWs). The resonance frequency of SAWs generated by the SFITs depends on the location of its parallel pathway; the particles at different locations of the SAWs' pathway can be controlled selectively by choosing the frequency of the excitation signal applied on the SFITs. By adjusting the input signal continuously, MBs can be transported along the acoustic aperture precisely. The displacement of MBs has a linear relationship with the frequency shift. The resolution of transportation is 15.19 ± 2.65 μm when the shift of input signal frequency is at a step of 10 kHz. In addition, the MBs can be controlled in a two-dimensional plane by combining variations of the frequency and the relative phase of the excitation signal applied on the SFITs simultaneously. This technology may open up the possibility of selectively and flexibly manipulating MBs using a simple one-dimensional device. PMID:27462381

  11. Spatial selective manipulation of microbubbles by tunable surface acoustic waves.

    PubMed

    Zhou, Wei; Niu, Lili; Cai, Feiyan; Li, Fei; Wang, Chen; Huang, Xiaowei; Wang, Jingjing; Wu, Junru; Meng, Long; Zheng, Hairong

    2016-05-01

    A microfluidic device based on a pair of slant-finger interdigital transducers (SFITs) is developed to achieve a selective and flexible manipulation of microbubbles (MBs) by surface acoustic waves (SAWs). The resonance frequency of SAWs generated by the SFITs depends on the location of its parallel pathway; the particles at different locations of the SAWs' pathway can be controlled selectively by choosing the frequency of the excitation signal applied on the SFITs. By adjusting the input signal continuously, MBs can be transported along the acoustic aperture precisely. The displacement of MBs has a linear relationship with the frequency shift. The resolution of transportation is 15.19 ± 2.65 μm when the shift of input signal frequency is at a step of 10 kHz. In addition, the MBs can be controlled in a two-dimensional plane by combining variations of the frequency and the relative phase of the excitation signal applied on the SFITs simultaneously. This technology may open up the possibility of selectively and flexibly manipulating MBs using a simple one-dimensional device. PMID:27462381

  12. Backward propagating acoustic waves in single gold nanobeams

    NASA Astrophysics Data System (ADS)

    Jean, Cyril; Belliard, Laurent; Becerra, Loïc; Perrin, Bernard

    2015-11-01

    Femtosecond pump-probe spectroscopy has been carried out on suspended gold nanostructures with a rectangular cross section lithographed on a silicon substrate. With a thickness fixed to 110 nm and a width ranging from 200 nm to 800 nm , size dependent measurements are used to distinguish which confined acoustic modes are detected. Furthermore, in order to avoid any ambiguity due to the measurement uncertainties on both the frequency and size, pump and probe beams are also spatially shifted to detect guided acoustic phonons. This leads us to the observation of backward propagating acoustic phonons in the gigahertz range ( ˜3 GHz ) in such nanostructures. While backward wave propagation in elastic waveguides has been predicted and already observed at the macroscale, very few studies have been done at the nanoscale. Here, we show that these backward waves can be used as the unique signature of the width dilatational acoustic mode.

  13. Universal Quantum Transducers Based on Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Schuetz, M. J. A.; Kessler, E. M.; Giedke, G.; Vandersypen, L. M. K.; Lukin, M. D.; Cirac, J. I.

    2015-07-01

    We propose a universal, on-chip quantum transducer based on surface acoustic waves in piezoactive materials. Because of the intrinsic piezoelectric (and/or magnetostrictive) properties of the material, our approach provides a universal platform capable of coherently linking a broad array of qubits, including quantum dots, trapped ions, nitrogen-vacancy centers, or superconducting qubits. The quantized modes of surface acoustic waves lie in the gigahertz range and can be strongly confined close to the surface in phononic cavities and guided in acoustic waveguides. We show that this type of surface acoustic excitation can be utilized efficiently as a quantum bus, serving as an on-chip, mechanical cavity-QED equivalent of microwave photons and enabling long-range coupling of a wide range of qubits.

  14. Formation of Hydro-acoustic Waves in Dissipative Coupled Weakly Compressible Fluids

    NASA Astrophysics Data System (ADS)

    Abdolali, A.; Kirby, J. T., Jr.; Bellotti, G.

    2014-12-01

    Recent advances in deep sea measurement technology provide an increasing opportunity to detect and interpret hydro-acoustic waves as a component in improved Tsunami Early Warning Systems (TEWS). For the idealized case of a homogeneous water column above a moving but otherwise rigid bottom (in terms of assessing acoustic wave interaction), the description of the infinite family of acoustic modes is characterized by local water depth at source area; i.e. the period of the first acoustic mode is given by four times the required time for sound to travel from the seabed to the surface. Spreading off from earthquake zone, the dominant spectrum is filtered and enriched by seamounts and barriers. This study focuses on the characteristics of hydro-acoustic waves generated by sudden sea bottom motion in a weakly compressible fluid coupled with an underlying sedimentary layer, where the added complexity of the sediment layer rheology leads to both the lowering of dominant spectral peaks and wave attenuation across the full spectrum. To overcome the computational difficulties of three-dimensional models, we derive a depth integrated equation valid for varying water depth and sediment thickness. Damping behavior of the two layered system is initially taken into account by introducing the viscosity of fluid-like sedimentary layer. We show that low frequency pressure waves which are precursor components of tsunamis contain information of seafloor motion.

  15. A theoretical prediction of the acoustic pressure generated by turbulence-flame front interactions

    NASA Technical Reports Server (NTRS)

    Huff, R. G.

    1984-01-01

    The equations of momentum and continuity are combined and linearized yielding the one dimensional nonhomogeneous acoustic wave equation. Three terms in the non-homogeneous equation act as acoustic sources and are taken to be forcing functions acting on the homogeneous wave equation. The three source terms are: fluctuating entropy, turbulence gradients, and turbulence-flame interactions. Each source term is discussed. The turbulence-flame interaction source is used as the basis for computing the source acoustic pressure from the Fourier transformed wave equation. Pressure fluctuations created in turbopump gas generators and turbines may act as a forcing function for turbine and propellant tube vibrations in earth to orbit space propulsion systems and could reduce their life expectancy. A preliminary assessment of the acoustic pressure fluctuations in such systems is presented.

  16. A theoretical prediction of the acoustic pressure generated by turbulence-flame front interactions

    NASA Technical Reports Server (NTRS)

    Huff, R. G.

    1984-01-01

    The equations of momentum annd continuity are combined and linearized yielding the one dimensional nonhomogeneous acoustic wave equation. Three terms in the non-homogeneous equation act as acoustic sources and are taken to be forcing functions acting on the homogeneous wave equation. The three source terms are: fluctuating entropy, turbulence gradients, and turbulence-flame interactions. Each source term is discussed. The turbulence-flame interaction source is used as the basis for computing the source acoustic pressure from the Fourier transformed wave equation. Pressure fluctuations created in turbopump gas generators and turbines may act as a forcing function for turbine and propellant tube vibrations in Earth to orbit space propulsion systems and could reduce their life expectancy. A preliminary assessment of the acoustic pressure fluctuations in such systems is presented.

  17. Modeling and experimental analysis of acoustic cavitation bubbles for Burst Wave Lithotripsy

    PubMed Central

    Maeda, Kazuki; Colonius, Tim; Kreider, Wayne; Maxwell, Adam; Cunitz, Bryan; Bailey, Michael

    2016-01-01

    A combined modeling and experimental study of acoustic cavitation bubbles that are initiated by focused ultrasound waves is reported. Focused ultrasound waves of frequency 335 kHz and peak negative pressure 8 MPa are generated in a water tank by a piezoelectric transducer to initiate cavitation. The resulting pressure field is obtained by direct numerical simulation (DNS) and used to simulate single bubble oscillation. The characteristics of cavitation bubbles observed by high-speed photography qualitatively agree withs the simulation result. Finally, bubble clouds are captured using acoustic B-mode imaging that works in synchronization with high-speed photography. PMID:27087826

  18. Coherent reflection from surface gravity water waves during reciprocal acoustic transmissions.

    PubMed

    Badiey, Mohsen; Song, Aijun; Smith, Kevin B

    2012-10-01

    During a recent experiment in Kauai, Hawaii, reciprocal transmissions were conducted between two acoustic transceivers mounted on the seafloor at a depth of 100 m. The passage of moving surface wave crests was shown to generate focused and intense coherent acoustic returns, which had increasing or decreasing delay depending on the direction of propagation relative to the direction of surface wave crests. It is shown that a rough surface two-dimensional parabolic equation model with an evolving sea surface can produce qualitative agreement with data for the dynamic surface returns. PMID:23039567

  19. Beam distortion detection and deflectometry measurements of gigahertz surface acoustic waves.

    PubMed

    Higuet, Julien; Valier-Brasier, Tony; Dehoux, Thomas; Audoin, Bertrand

    2011-11-01

    Gigahertz acoustic waves propagating on the surface of a metal halfspace are detected using different all-optical detection schemes, namely, deflectometry and beam distortion detection techniques. Both techniques are implemented by slightly modifying a conventional reflectometric setup. They are then based on the measurement of the reflectivity change but unlike reflectometric measurements, they give access to the sample surface displacement. A semi-analytical model, taking into account optical, thermal, and mechanical processes responsible for acoustic waves generation, allows analyzing the physical content of the detected waveforms. PMID:22129002

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

    PubMed

    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

  1. Electron-acoustic solitary waves in a nonextensive plasma

    SciTech Connect

    Tribeche, Mouloud; Djebarni, Lyes

    2010-12-15

    The problem of arbitrary amplitude electron-acoustic solitary waves (EASWs) in a plasma having cold fluid electrons, hot nonextensive electrons, and stationary ions is addressed. It is found that the 'Maxwellianization' process of the hot nonextensive component does not favor the propagation of the EASWs. In contrast to superthermality, nonextensivity makes the electron-acoustic solitary structure less spiky. Our theoretical analysis brings a possibility to develop more refined theories of nonlinear solitary structures in astrophysical plasmas.

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

    PubMed

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

    2011-10-12

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

  3. Probing Thermomechanics at the Nanoscale: Impulsively Excited Pseudosurface Acoustic Waves in Hypersonic Phononic Crystals

    PubMed Central

    2011-01-01

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

  4. Propagating Properties of Cylindrical Rayleigh Waves Generated by a Pulsed Laser Line Source

    NASA Astrophysics Data System (ADS)

    Hu, Wen-Xiang; Qian, Meng-Lu

    2004-07-01

    A two-dimensional theoretical model is used to analyse the acoustic field of cylindrical surface waves generated by a pulsed laser line source in the ablation regime. The complete dispersive curves for cylindrical Rayleigh wave are presented. The laser-generated transient acoustic field of cylindrical Rayleigh waves is calculated and the corresponding laser ultrasonic experiments are carried out. Both the numerical and experimental results are in good agreement.

  5. Controllable optical transparency using an acoustic standing-wave device

    NASA Astrophysics Data System (ADS)

    Moradi, Kamran; El-Zahab, Bilal

    2015-09-01

    In this paper, a suspended-particle device with controllable light transmittance was developed based on acoustic stimuli. Using a glass compartment and carbon particle suspension in an organic solvent, the device responded to acoustic stimulation by alignment of particles. The alignment of light-absorbing carbon particles afforded an increase in light transmittance as high as 84.5% and was controllable based on the control of the frequency and amplitude of the acoustic waves. The device also demonstrated alignment memory rendering it energy-efficient.

  6. Interaction of electromagnetic and acoustic waves in a stochastic atmosphere

    NASA Technical Reports Server (NTRS)

    Bhatnagar, N.; Frankel, M. S.; Peterson, A. M.

    1977-01-01

    This paper considers the interaction of electromagnetic and acoustic waves where a Radio Acoustic Sounding System (RASS) is operated in a stochastic environment characterized by turbulence, winds and mean-temperature gradients. It has been shown that for a RASS operating at acoustic frequencies below a few kilohertz propagating under typical atmospheric conditions, turbulence has little effect on the strength of the received radio signal scattered from the pulse at heights up to a few kilometers. This result implies that the received RF signal level (power) is primarily a function of sound intensity which decreases as x exp minus 2 where x is the altitude.

  7. Drift and ion acoustic wave driven vortices with superthermal electrons

    SciTech Connect

    Ali Shan, S.; Haque, Q.

    2012-08-15

    Linear and nonlinear analysis of coupled drift and acoustic mode is presented in an inhomogeneous electron-ion plasma with {kappa}-distributed electrons. A linear dispersion relation is found which shows that the phase speed of both the drift wave and the ion acoustic wave decreases in the presence of superthermal electrons. Several limiting cases are also discussed. In the nonlinear regime, stationary solutions in the form of dipolar and monopolar vortices are obtained. It is shown that the condition for the boundedness of the solution implies that the speed of drift wave driven vortices reduces with increase in superthermality effect. Ignoring density inhomogeniety, it is investigated that the lower and upper limits on the speed of the ion acoustic driven vortices spread with the inclusion of high energy electrons. The importance of results with reference to space plasmas is also pointed out.

  8. Surface Acoustic Wave Devices for Harsh Environment Wireless Sensing

    PubMed Central

    Greve, David W.; Chin, Tao-Lun; Zheng, Peng; Ohodnicki, Paul; Baltrus, John; Oppenheim, Irving J.

    2013-01-01

    Langasite surface acoustic wave devices can be used to implement harsh-environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensor with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity. PMID:23708273

  9. Surface acoustic wave devices for harsh environment wireless sensing

    SciTech Connect

    Greve, David W.; Chin, Tao -Lun; Zheng, Peng; Ohodnicki, Paul; Baltrus, John; Oppenheim, Irving J.

    2013-05-24

    In this study, langasite surface acoustic wave devices can be used to implement harsh environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensor with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity.

  10. Surface acoustic wave devices for harsh environment wireless sensing

    DOE PAGESBeta

    Greve, David W.; Chin, Tao -Lun; Zheng, Peng; Ohodnicki, Paul; Baltrus, John; Oppenheim, Irving J.

    2013-05-24

    In this study, langasite surface acoustic wave devices can be used to implement harsh environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensormore » with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity.« less

  11. Broadband metamaterial for nonresonant matching of acoustic waves

    NASA Astrophysics Data System (ADS)

    D'Aguanno, G.; Le, K. Q.; Trimm, R.; Alù, A.; Mattiucci, N.; Mathias, A. D.; Aközbek, N.; Bloemer, M. J.

    2012-03-01

    Unity transmittance at an interface between bulk media is quite common for polarized electromagnetic waves incident at the Brewster angle, but it is rarely observed for sound waves at any angle of incidence. In the following, we theoretically and experimentally demonstrate an acoustic metamaterial possessing a Brewster-like angle that is completely transparent to sound waves over an ultra-broadband frequency range with >100% bandwidth. The metamaterial, consisting of a hard metal with subwavelength apertures, provides a surface impedance matching mechanism that can be arbitrarily tailored to specific media. The nonresonant nature of the impedance matching effectively decouples the front and back surfaces of the metamaterial allowing one to independently tailor the acoustic impedance at each interface. On the contrary, traditional methods for acoustic impedance matching, for example in medical imaging, rely on resonant tunneling through a thin antireflection layer, which is inherently narrowband and angle specific.

  12. Oxygen acoustic solitary waves in a magnetized plasma

    NASA Technical Reports Server (NTRS)

    Qian, S.; Lotko, W.; Hudson, M. K.

    1989-01-01

    Ion-acoustic solitary waves in a magnetized plasma containing an arbitrary mixture of H(+) and O(+) ions are studied. A nonlinear wave equation has been derived from the Poisson-Vlasov equations, including a uniform magnetic field and dissipation due to reflected electrons. When dissipation is ignored, the equation has soliton solutions associated with both oxygen and hydrogen acoustic modes, which can be either rarefactive or compressive depending on the ion concentrations and the electron/ion temperature ratio and, more weakly, on the bulk drifts of the species. If electron reflection is included, the solitary wave can be intensified. Under somewhat restrictive conditions the oxygen solitary wave is rarefactive and propagates with a velocity comparable to that observed by the Viking satellite. The three-dimensional solitons obey a relation of scales parallel to the magnetic field and in the transverse direction. Computer simulations of one-dimensional versions of the nonlinear wave equation are presented.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Acoustic signals generated in inclined granular flows

    NASA Astrophysics Data System (ADS)

    Tan, Danielle S.; Jenkins, James T.; Keast, Stephen C.; Sachse, Wolfgang H.

    2015-10-01

    Spontaneous avalanching in specific deserts produces a low-frequency sound known as "booming." This creates a puzzle, because avalanches down the face of a dune result in collisions between sand grains that occur at much higher frequencies. Reproducing this phenomenon in the laboratory permits a better understanding of the underlying mechanisms for the generation of such lower frequency acoustic emissions, which may also be relevant to other dry granular flows. Here we report measurements of low-frequency acoustical signals, produced by dried "sounding" sand (sand capable of booming in the desert) flowing down an inclined chute. The amplitude of the signal diminishes over time but reappears upon drying of the sand. We show that the presence of this sound in the experiments may provide supporting evidence for a previously published "waveguide" explanation for booming. Also, we propose a model based on kinetic theory for a sheared inclined flow in which the flowing layer exhibits "breathing" modes superimposed on steady shearing. The predicted oscillation frequency is of a similar order of magnitude as the measurements, indicating that small perturbations can sustain oscillations of a low frequency. However, the frequency is underestimated, which indicates that the stiffness has been underestimated. Also, the model predicts a discrete spectrum of frequencies, instead of the broadband spectrum measured experimentally.

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

    PubMed

    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. PMID:26822429

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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. PMID:26822429

  18. Measurements of the force fields within an acoustic standing wave using holographic optical tweezers

    SciTech Connect

    Bassindale, P. G.; Drinkwater, B. W.; Phillips, D. B.; Barnes, A. C.

    2014-04-21

    Direct measurement of the forces experienced by micro-spheres in an acoustic standing wave device have been obtained using calibrated optical traps generated with holographic optical tweezers. A micro-sphere, which is optically trapped in three dimensions, can be moved through the acoustic device to measure forces acting upon it. When the micro-sphere is subjected to acoustic forces, it's equilibrium position is displaced to a position where the acoustic forces and optical forces are balanced. Once the optical trapping stiffness has been calibrated, observation of this displacement enables a direct measurement of the forces acting upon the micro-sphere. The measured forces are separated into a spatially oscillating component, attributed to the acoustic radiation force, and a constant force, attributed to fluid streaming. As the drive conditions of the acoustic device were varied, oscillating forces (>2.5 pN{sub pp}) and streaming forces (<0.2 pN) were measured. A 5 μm silica micro-sphere was used to characterise a 6.8 MHz standing wave, λ = 220 μm, to a spatial resolution limited by the uncertainty in the positioning of the micro-sphere (here to within 2 nm) and with a force resolution on the order of 10 fN. The results have application in the design and testing of acoustic manipulation devices.

  19. A pseudo-spin surface-acoustic-wave quantum computer.

    PubMed

    Barnes, C H W

    2003-07-15

    A modification to the surface-acoustic-wave quantum computer is described. The use of pseudo-spin qubits is introduced as a way to simplify the fabrication and programming of the computer. A form of optical readout that relies on the electrons in each surface-acoustic-wave minimum recombining with holes in a two-dimensional hole gas is suggested as a means to measure the output. The suggested modification would allow the quantum computer to be made smaller and to operate faster. PMID:12869323

  20. Particle-Wave Micro-Dynamics in Nonlinear Self-Excited Dust Acoustic Waves

    SciTech Connect

    Tsai, C.-Y.; Teng, L.-W.; Liao, C.-T.; I Lin

    2008-09-07

    The large amplitude dust acoustic wave can be self-excited in a low-pressure dusty plasma. In the wave, the nonlinear wave-particle interaction determines particle motion, which in turn determines the waveform and wave propagation. In this work, the above behaviors are investigated by directly tracking particle motion through video-microscopy. A Lagrangian picture for the wave dynamics is constructed. The wave particle interaction associated with the transition from ordered to disordered particle oscillation, the wave crest trapping and wave heating are demonstrated and discussed.

  1. Lithosphere-Atmosphere coupling: Spectral element modeling of the evolution of acoustic waves in the atmosphere from an underground source.

    NASA Astrophysics Data System (ADS)

    Averbuch, Gil; Price, Colin

    2015-04-01

    Lithosphere-Atmosphere coupling: Spectral element modeling of the evolution of acoustic waves in the atmosphere from an underground source. G. Averbuch, C. Price Department of Geosciences, Tel Aviv University, Israel Infrasound is one of the four Comprehensive Nuclear-Test Ban Treaty technologies for monitoring nuclear explosions. This technology measures the acoustic waves generated by the explosions followed by their propagation through the atmosphere. There are also natural phenomena that can act as an infrasound sources like sprites, volcanic eruptions and earthquakes. The infrasound waves generated from theses phenomena can also be detected by the infrasound arrays. In order to study the behavior of these waves, i.e. the physics of wave propagation in the atmosphere, their evolution and their trajectories, numerical methods are required. This presentation will deal with the evolution of acoustic waves generated by underground sources (earthquakes and underground explosions). A 2D Spectral elements formulation for lithosphere-atmosphere coupling will be presented. The formulation includes the elastic wave equation for the seismic waves and the momentum, mass and state equations for the acoustic waves in a moving stratified atmosphere. The coupling of the two media is made by boundary conditions that ensures the continuity of traction and velocity (displacement) in the normal component to the interface. This work has several objectives. The first is to study the evolution of acoustic waves in the atmosphere from an underground source. The second is to derive transmission coefficients for the energy flux with respect to the seismic magnitude and earth density. The third will be the generation of seismic waves from acoustic waves in the atmosphere. Is it possible?

  2. Effects of acoustic wave resonance oscillation on immobilized enzyme

    NASA Astrophysics Data System (ADS)

    Nishiyama, Hiroshi; Watanabe, Tomoya; Inoue, Yasunobu

    2014-03-01

    In aiming at developing a new method to artificially activate enzyme catalysts immobilized on surface, the effects of resonance oscillation of bulk acoustic waves were studied. Glucose oxidase (GOD) was immobilized by a covalent coupling method on a ferroelectric lead zirconate titanate (PZT) device that was able to generate thickness-extensional resonance oscillation (TERO). Glucose oxidation by the GOD enzyme was studied in a microreactor. The generation of TERO immediately increased the catalytic activity of immobilized GOD by a factor of 2-3. With turn-off of TERO, no significant activity decrease occurred, and 80-90% of the enhanced activity was maintained while the reaction proceeded. The almost complete reversion of the activity to the original low level before TERO generation was observed when the immobilized GOD was exposed to a glucose substrate-free solution. These results indicated that the presence of glucose substrate was essential for TERO-induced GOD activation and preservation of the increased activity level. The influences of reaction temperature, glucose concentration, pH, and rf electric power on the TERO activation showed that TERO strengthened the interactions of the immobilized enzyme with glucose substrate and hence promoted the formation of an activation complex.

  3. Nonlinear focusing of acoustic shock waves at a caustic cusp.

    PubMed

    Marchiano, Régis; Coulouvrat, François; Thomas, Jean-Louis

    2005-02-01

    The present study investigates the focusing of acoustical weak shock waves incoming on a cusped caustic. The theoretical model is based on the Khokhlov-Zabolotskaya equation and its specific boundary conditions. Based on the so-called Guiraud's similitude law for a step shock, a new explanation about the wavefront unfolding due to nonlinear self-refraction is proposed. This effect is shown to be associated not only to nonlinearities, as expected by previous authors, but also to the nonlocal geometry of the wavefront. Numerical simulations confirm the sensitivity of the process to wavefront geometry. Theoretical modeling and numerical simulations are substantiated by an original experiment. This one is carried out in two steps. First, the canonical Pearcey function is synthesized in linear regime by the inverse filter technique. In the second step, the same wavefront is emitted but with a high amplitude to generate shock waves during the propagation. The experimental results are compared with remarkable agreement to the numerical ones. Finally, applications to sonic boom are briefly discussed. PMID:15759678

  4. Linear coupling of acoustic and cyclotron waves in plasma flows

    SciTech Connect

    Rogava, Andria; Gogoberidze, Grigol

    2005-05-15

    It is found that in magnetized electrostatic plasma flows the velocity shear couples ion-acoustic waves with ion-cyclotron waves and leads, under favorable conditions, to their efficient reciprocal transformations. It is shown that in a two-dimensional setup this coupling has a remarkable feature: it is governed by equations that are mathematically equal to the ones describing coupling of sound waves with internal gravity waves [Rogava and Mahajan, Phys. Rev. E 55, 1185 (1997)] in neutral fluids. For flows with low shearing rates a fully analytic, quantitative description of the coupling efficiency, based on a noteworthy quantum-mechanical analogy, is given and transformation coefficients are calculated.

  5. Trapping and Frequency Variability in Electron Acoustic Waves

    SciTech Connect

    Driscoll, C. F.; Anderegg, F.; Dubin, D. H. E.; O'Neil, T. M.

    2009-11-10

    Electron Acoustic Waves (EAWs) with a phase velocity less than twice the plasma thermal velocity are observed on pure ion plasma columns. At low excitation amplitudes, the EAW frequencies agree with theory; but at moderate excitation the EAW is more frequency-variable than typical Langmuir waves, and at large excitations resonance is observed over a broad range. Laser Induced Fluorescence measurements of the wave-coherent ion velocity distribution show phase-reversals and wave-particle trapping plateaux at {+-}v{sub ph}, as expected, and corroborate the unusual role of kinetic pressure in the EAW.

  6. Linear coupling of acoustic and cyclotron waves in plasma flows

    NASA Astrophysics Data System (ADS)

    Rogava, Andria; Gogoberidze, Grigol

    2005-05-01

    It is found that in magnetized electrostatic plasma flows the velocity shear couples ion-acoustic waves with ion-cyclotron waves and leads, under favorable conditions, to their efficient reciprocal transformations. It is shown that in a two-dimensional setup this coupling has a remarkable feature: it is governed by equations that are mathematically equal to the ones describing coupling of sound waves with internal gravity waves [Rogava and Mahajan, Phys. Rev. E 55, 1185 (1997)] in neutral fluids. For flows with low shearing rates a fully analytic, quantitative description of the coupling efficiency, based on a noteworthy quantum-mechanical analogy, is given and transformation coefficients are calculated.

  7. Chromospheric Heating by Acoustic Waves Compared to Radiative Cooling

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of the solar atmosphere. A weak chromospheric plage near the large solar pore NOAA 11005 was observed on 2008 October 15, in the Fe i 617.3 nm and Ca ii 853.2 nm lines of the Interferometric Bidimemsional Spectrometer attached to the Dunn Solar Telescope. In analyzing the Ca ii observations (with spatial and temporal resolutions of 0.″4 and 52 s) the energy deposited by acoustic waves is compared to that released by radiative losses. The deposited acoustic flux is estimated from the power spectra of Doppler oscillations measured in the Ca ii line core. The radiative losses are calculated using a grid of seven one-dimensional hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of the maps of radiative losses and acoustic flux is 72%. In a quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only about 15%. In active areas with a photospheric magnetic-field strength between 300 and 1300 G and an inclination of 20°–60°, the contribution increases from 23% (chromospheric network) to 54% (a plage). However, these values have to be considered as lower limits and it might be possible that the acoustic energy flux is the main contributor to the heating of bright chromospheric network and plages.

  8. Waveform inversion of acoustic waves for explosion yield estimation

    DOE PAGESBeta

    Kim, K.; Rodgers, A. J.

    2016-07-08

    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 explosionmore » yield based on a standard air blast model. The technique was applied to local explosions (<10 km) and provided reasonable yield estimates (<~30% error) in the presence of realistic topography and atmospheric structure. In conclusion, the presented method can be extended to explosions recorded at far distance provided proper meteorological specifications.« less

  9. Chromospheric extents predicted by time-dependent acoustic wave models

    SciTech Connect

    Cuntz, M. Heidelberg Universitaet )

    1990-01-01

    Theoretical models for chromospheric structures of late-type giant stars are computed, including the time-dependent propagation of acoustic waves. Models with short-period monochromatic shock waves as well as a spectrum of acoustic waves are discussed, and the method is applied to the stars Arcturus, Aldebaran, and Betelgeuse. Chromospheric extent, defined as the monotonic decrease with height of the time-averaged electron densities, are found to be 1.12, 1.13, and 1.22 stellar radii for the three stars, respectively; this corresponds to a time-averaged electron density of 10 to the 7th/cu cm. Predictions of the extended chromospheric obtained using a simple scaling law agree well with those obtained by the time-dependent wave models; thus, the chromospheres of all stars for which the scaling law is valid consist of the same number of pressure scale heights. 74 refs.

  10. Chromospheric extents predicted by time-dependent acoustic wave models

    NASA Technical Reports Server (NTRS)

    Cuntz, Manfred

    1990-01-01

    Theoretical models for chromospheric structures of late-type giant stars are computed, including the time-dependent propagation of acoustic waves. Models with short-period monochromatic shock waves as well as a spectrum of acoustic waves are discussed, and the method is applied to the stars Arcturus, Aldebaran, and Betelgeuse. Chromospheric extent, defined as the monotonic decrease with height of the time-averaged electron densities, are found to be 1.12, 1.13, and 1.22 stellar radii for the three stars, respectively; this corresponds to a time-averaged electron density of 10 to the 7th/cu cm. Predictions of the extended chromospheric obtained using a simple scaling law agree well with those obtained by the time-dependent wave models; thus, the chromospheres of all stars for which the scaling law is valid consist of the same number of pressure scale heights.

  11. Acoustic and elastic waves in metamaterials for underwater applications

    NASA Astrophysics Data System (ADS)

    Titovich, Alexey S.

    Elastic effects in acoustic metamaterials are investigated. Water-based periodic arrays of elastic scatterers, sonic crystals, suffer from low transmission due to the impedance and index mismatch of typical engineering materials with water. A new type of acoustic metamaterial element is proposed that can be tuned to match the acoustic properties of water in the quasi-static regime. The element comprises a hollow elastic cylindrical shell fitted with an optimized internal substructure consisting of a central mass supported by an axisymmetric distribution of elastic stiffeners, which dictate the shell's effective bulk modulus and density. The derived closed form scattering solution for this system shows that the subsonic flexural waves excited in the shell by the attachment of stiffeners are suppressed by including a sufficiently large number of such stiffeners. As an example of refraction-based wave steering, a cylindrical-to-plane wave lens is designed by varying the bulk modulus in the array according to the conformal mapping of a unit circle to a square. Elastic shells provide rich scattering properties, mainly due to their ability to support highly dispersive flexural waves. Analysis of flexural-borne waves on a pair of shells yields an analytical expression for the width of a flexural resonance, which is then used with the theory of multiple scattering to accurately predict the splitting of the resonance frequency. This analysis leads to the discovery of the acoustic Poisson-like effect in a periodic wave medium. This effect redirects an incident acoustic wave by 90° in an otherwise acoustically transparent sonic crystal. An unresponsive "deaf" antisymmetric mode locked to band gap boundaries is unlocked by matching Bragg scattering with a quadrupole flexural resonance of the shell. The dynamic effect causes normal unidirectional wave motion to strongly couple to perpendicular motion, analogous to the quasi-static Poisson effect in solids. The Poisson

  12. Adiabatic trapping in coupled kinetic Alfven-acoustic waves

    SciTech Connect

    Shah, H. A.; Ali, Z.; Masood, W.

    2013-03-15

    In the present work, we have discussed the effects of adiabatic trapping of electrons on obliquely propagating Alfven waves in a low {beta} plasma. Using the two potential theory and employing the Sagdeev potential approach, we have investigated the existence of arbitrary amplitude coupled kinetic Alfven-acoustic solitary waves in both the sub and super Alfvenic cases. The results obtained have been analyzed and presented graphically and can be applied to regions of space where the low {beta} assumption holds true.

  13. Ion-Acoustic Waves in Self-Gravitaing Dusty Plasma

    SciTech Connect

    Kumar, Nagendra; Kumar, Vinod; Kumar, Anil

    2008-09-07

    The propagation and damping of low frequency ion-acoustic waves in steady state, unmagnetised, self-gravitating dusty plasma are studied taking into account two important damping mechanisms creation damping and Tromso damping. It is found that imaginary part of wave number is independent of frequency in case of creation damping. But when we consider the case of creation and Tromso damping together, an additional contribution to damping appears with the increase in frequency attributed to Tromso effect.

  14. S-Band Shallow Bulk Acoustic Wave (SBAW) microwave source

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Techniques necessary to fabricate a high performance S-band microwave single source using state-of-the-art shallow bulk acoustic wave (SBAW) were explored. The bulk wave structures of the AlN/Al 2O3 were investigated for both the R plane and basal plane of sapphire. A 1.072 GHz SBAW delay line and oscillators were developed. A method of selecting and setting oscillator output frequency by selecting substrate orientation angle was also established.

  15. Dust acoustic shock waves in two temperatures charged dusty grains

    SciTech Connect

    El-Shewy, E. K.; Abdelwahed, H. G.; Elmessary, M. A.

    2011-11-15

    The reductive perturbation method has been used to derive the Korteweg-de Vries-Burger equation and modified Korteweg-de Vries-Burger for dust acoustic shock waves in a homogeneous unmagnetized plasma having electrons, singly charged ions, hot and cold dust species with Boltzmann distributions for electrons and ions in the presence of the cold (hot) dust viscosity coefficients. The behavior of the shock waves in the dusty plasma has been investigated.

  16. Submarine volcanic activity, ocean-acoustic waves and internal ocean tides

    NASA Astrophysics Data System (ADS)

    Sugioka, Hiroko; Fukao, Yoshio; Hibiya, Toshiyuki

    2005-12-01

    Submarine volcanic event often generates acoustic waves (T-waves) traveling over long distances through the low velocity channel (SOFAR) of the ocean. By a method of coherent stacking of T-waves from a submarine volcanic activity in northern Mariana, we found a significant semidiurnal variation of T-wave travel times. The amplitude of variation is an order of larger than those reported in the previous ocean sound transmission experiments. Ray-theoretical consideration for the numerically simulated ocean tides indicates that such large T-phase travel time variation is a consequence of large up-and-down movement of seawater around the axis of the SOFAR channel due to the M2 internal tide effectively converted from external tidal forcing. T-phases, a ubiquitous feature of the ocean acoustic noise field, can be used to infer internal tidal motion and the associated ocean mixing.

  17. Evolution of nonlinear ion-acoustic solitary wave propagation in rotating plasma

    SciTech Connect

    Das, G. C.; Nag, Apratim

    2006-08-15

    A simple unmagnetized plasma rotating around an axis at an angle {theta} with the propagation direction of the acoustic mode has been taken. The nonlinear wave mode has been derived as an equivalent Sagdeev potential equation. A special procedure, known as the tanh method, has been developed to study the nonlinear wave propagation in plasma dynamics. Further, under small amplitude approximation, the nonlinear plasma acoustic mode has been exploited to study the evolution of soliton propagation in the plasma. The main emphasis has been given to the interaction of Coriolis force on the changes of coherent structure of the soliton. The solitary wave solution finds the different nature of solitons called compressive and rarefactive solitons as well as its explosions or collapses along with soliton dynamics and these have been showing exciting observations in exhibiting a narrow wave packet with the generation of high electric pressure and the growth of high energy which, in turn, yields the phenomena of radiating soliton in dynamics.

  18. Producing ion waves from acoustic pressure waves in pulsed ICP: Modeling vs. Experiments

    NASA Astrophysics Data System (ADS)

    Despiau-Pujo, Emilie; Cunge, Gilles; Darnon, Maxime; Sadeghi, Nader; Braithwaite, Nicholas

    2015-09-01

    Neutral depletion is an important phenomenon in CW high-density plasmas, mostly caused by gas heating - with a small contribution due to electron pressure Pe - under typical material processing conditions. In pulsed ICP, neutral depletion plays an important role on radical transport in the afterglow. At the beginning of the afterglow, Pe drops rapidly (10 μs) by electron cooling and the gas cools down as well. It generates a neutral pressure gradient between the plasma bulk and the reactor walls, which in turn forces the cold surrounding gas to move rapidly towards the center, thus launching an acoustic wave in the reactor. Fast gas displacement is evidenced by measuring Al atoms drift velocity in the early afterglow of a Cl2/Ar discharge by time-resolved LIF, the acoustic wave in the chamber being observed by mass spectrometry. 2D fluid simulations of Cl2 pulsed ICP predict similar results. These phenomena are further studied during both the plasma ignition and afterglow using modeling and experiments. Strong oscillations are observed both on the Cl2 neutral densities and on the ion flux. As neutrals are pushed towards (or outwards) the chamber walls by the pressure gradient, ions are also pushed in that direction through collisions, as well captured by our ion flux probe.

  19. Numerical modelling of nonlinear full-wave acoustic propagation

    NASA Astrophysics Data System (ADS)

    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.

  20. Numerical modelling of nonlinear full-wave acoustic propagation

    SciTech Connect

    Velasco-Segura, Roberto Rendón, Pablo L.

    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.

  1. Propagation of acoustic pulses in random gravity wave fields

    NASA Astrophysics Data System (ADS)

    Millet, Christophe; de La Camara, Alvaro; Lott, François

    2015-11-01

    A linear solution modeling the interaction between an incoming acoustic wave and a randomly perturbed atmosphere is developed, using the normal mode method. The wave mode structure is determined by a sound speed profile that is confining. The environmental uncertainty is described by a stochastic field obtained with a multiwave stochastic parameterization of gravity waves (GW). Using the propagating modes of the unperturbed atmosphere, the wave propagation problem is reduced to solving a system of ordinary differential equations. We focus on the asymptotic behavior of the transmitted waves in the weakly heterogeneous regime. In this regime, the coupling between the acoustic pulse and the randomly perturbed waveguides is weak and the propagation distance must be large enough for the wave to experience significant scattering. A general expression for the pressure far-field is derived in terms of saddle-point contributions. The saddle-points are obtained from a WKB approximation of the vertical eigenvalue problem. We present preliminary results that show how statistics of the transmitted signal are related to some eigenvalues and how an ``optimal'' GW field can trigger large deviations in the acoustic signals. The present model is used to explain the variability of infrasound signals.

  2. Traveling surface spin-wave resonance spectroscopy using surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Gowtham, P. G.; Moriyama, T.; Ralph, D. C.; Buhrman, R. A.

    2015-12-01

    Coherent gigahertz-frequency surface acoustic waves (SAWs) traveling on the surface of a piezoelectric crystal can, via the magnetoelastic interaction, resonantly excite traveling surface spin waves in an adjacent thin-film ferromagnet. These excited surface spin waves, traveling with a definite in-plane wave-vector q ∥ enforced by the SAW, can be detected by measuring changes in the electro-acoustical transmission of a SAW delay line. Here, we provide a demonstration that such measurements constitute a precise and quantitative technique for spin-wave spectroscopy, providing a means to determine both isotropic and anisotropic contributions to the spin-wave dispersion and damping. We demonstrate the effectiveness of this spectroscopic technique by measuring the spin-wave properties of a Ni thin film for a large range of wave vectors, | q ∥ | = 2.5 × 104-8 × 104 cm-1, over which anisotropic dipolar interactions vary from being negligible to quite significant.

  3. Corrigendum and addendum. Modeling weakly nonlinear acoustic wave propagation

    DOE PAGESBeta

    Christov, Ivan; Christov, C. I.; Jordan, P. M.

    2014-12-18

    This article presents errors, corrections, and additions to the research outlined in the following citation: Christov, I., Christov, C. I., & Jordan, P. M. (2007). Modeling weakly nonlinear acoustic wave propagation. The Quarterly Journal of Mechanics and Applied Mathematics, 60(4), 473-495.

  4. Gas dynamical approach to study dust acoustic solitary waves

    SciTech Connect

    Maitra, Sarit; Roychoudhury, Rajkumar

    2005-06-15

    Dust acoustic nonlinear waves are studied using gas dynamical approach. The structure equation for dust fluid has been obtained using the conservation laws for mass flux and momentum. The role of dust sonic point for the formation of soliton has been discussed. Conditions for the existence of soliton have been derived in terms of collective Mach number, taking into account the dust charge variation.

  5. Gasoline identifier based on SH0 plate acoustic waves.

    PubMed

    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

  6. Experimental observation of acoustic emissions generated by a pulsed proton beam from a hospital-based clinical cyclotron

    SciTech Connect

    Jones, Kevin C.; Solberg, Timothy D.; Avery, Stephen; Vander Stappen, François; Janssens, Guillaume; Prieels, Damien; Bawiec, Christopher R.; Lewin, Peter A.; Sehgal, Chandra M.

    2015-12-15

    Purpose: To measure the acoustic signal generated by a pulsed proton spill from a hospital-based clinical cyclotron. Methods: An electronic function generator modulated the IBA C230 isochronous cyclotron to create a pulsed proton beam. The acoustic emissions generated by the proton beam were measured in water using a hydrophone. The acoustic measurements were repeated with increasing proton current and increasing distance between detector and beam. Results: The cyclotron generated proton spills with rise times of 18 μs and a maximum measured instantaneous proton current of 790 nA. Acoustic emissions generated by the proton energy deposition were measured to be on the order of mPa. The origin of the acoustic wave was identified as the proton beam based on the correlation between acoustic emission arrival time and distance between the hydrophone and proton beam. The acoustic frequency spectrum peaked at 10 kHz, and the acoustic pressure amplitude increased monotonically with increasing proton current. Conclusions: The authors report the first observation of acoustic emissions generated by a proton beam from a hospital-based clinical cyclotron. When modulated by an electronic function generator, the cyclotron is capable of creating proton spills with fast rise times (18 μs) and high instantaneous currents (790 nA). Measurements of the proton-generated acoustic emissions in a clinical setting may provide a method for in vivo proton range verification and patient monitoring.

  7. Impact of Acoustic Standing Waves on Structural Responses: Reverberant Acoustic Testing (RAT) vs. Direct Field Acoustic Testing (DFAT)

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu

    2012-01-01

    Loudspeakers have been used for acoustic qualification of spacecraft, reflectors, solar panels, and other acoustically responsive structures for more than a decade. Limited measurements from some of the recent speaker tests used to qualify flight hardware have indicated significant spatial variation of the acoustic field within the test volume. Also structural responses have been reported to differ when similar tests were performed using reverberant chambers. To address the impact of non-uniform acoustic field on structural responses, a series of acoustic tests were performed using a flat panel and a 3-ft cylinder exposed to the field controlled by speakers and repeated in a reverberant chamber. The speaker testing was performed using multi-input-single-output (MISO) and multi-input-multi-output (MIMO) control schemes with and without the test articles. In this paper the spatial variation of the acoustic field due to acoustic standing waves and their impacts on the structural responses in RAT and DFAT (both using MISO and MIMO controls for DFAT) are discussed in some detail.

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

    SciTech Connect

    Zhou, Xiaoming; Badreddine Assouar, M. Oudich, Mourad

    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.

  9. Experimental and numerical investigations of resonant acoustic waves in near-critical carbon dioxide.

    PubMed

    Hasan, Nusair; Farouk, Bakhtier

    2015-10-01

    Flow and transport induced by resonant acoustic waves in a near-critical fluid filled cylindrical enclosure is investigated both experimentally and numerically. Supercritical carbon dioxide (near the critical or the pseudo-critical states) in a confined resonator is subjected to acoustic field created by an electro-mechanical acoustic transducer and the induced pressure waves are measured by a fast response pressure field microphone. The frequency of the acoustic transducer is chosen such that the lowest acoustic mode propagates along the enclosure. For numerical simulations, a real-fluid computational fluid dynamics model representing the thermo-physical and transport properties of the supercritical fluid is considered. The simulated acoustic field in the resonator is compared with measurements. The formation of acoustic streaming structures in the highly compressible medium is revealed by time-averaging the numerical solutions over a given period. Due to diverging thermo-physical properties of supercritical fluid near the critical point, large scale oscillations are generated even for small sound field intensity. The strength of the acoustic wave field is found to be in direct relation with the thermodynamic state of the fluid. The effects of near-critical property variations and the operating pressure on the formation process of the streaming structures are also investigated. Irregular streaming patterns with significantly higher streaming velocities are observed for near-pseudo-critical states at operating pressures close to the critical pressure. However, these structures quickly re-orient to the typical Rayleigh streaming patterns with the increase operating pressure. PMID:26520322

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

    PubMed

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

    2012-08-01

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

  11. Joint interpretation of infrasound, acoustic, and seismic waves from meteorites: Chelyabinsk bolide and other events

    NASA Astrophysics Data System (ADS)

    Kitov, Ivan; Rozhkov, Mikhail; Bobrov, Dmitry; Ovtchinnikov, Vladimir

    2014-05-01

    Meteorites are always the events that testing the capability of the International Monitoring System to measure and the International Data Centre to analyze sources similar to nuclear explosions. Monitoring of the Comprehensive Nuclear-Test-Ban Treaty suggests the possibility to detect infrasound (acoustic) and seismic signals from atmospheric and underground events and to locate their sources. Chelyabinsk meteor was one of the best exemplar in a row of other atmospheric events exposing the ability of IDC and IMS to handle the atmospheric explosions. The uniqueness of this event is that the generated seismic, acousto-seismic and infrasound wave fields were recorded by considerable number of IMS stations of different technologies at wide distance range. The shock waves from the Chelyabinsk meteor generated an I-phase recorded by IMS infrasound stations and a series of seismic phases. The Pn-waves were observed by five near-regional seismic stations together with Sn- and Lg-waves. They are most likely associated with the impact of the meteor debris and the location associated with their source differs by tens of kilometers from that obtained by Rayleigh and Love waves. The latter were generated by acoustic (low-amplitude shock) waves hitting the ground beneath the trajectory of the meteor. Surprisingly, these surface waves associated with the meteor and observed at least at distances of 45º were not associated with the event in the Reviewed Event Bulletin. This implies a conceptual gap in the IDC processing and fusion of acoustic and seismic waves. The trajectory of the meteorite built with the epicenters of seismic, acousto-seismic and infrasound events is in good compliance with the trajectories built by different scientific institutions including NASA. We present an approximate distribution of energy release along the trajectory and thus the amplitude of the generated shock wave. It allows interpreting the period and amplitude dependence of the LR and LQ waves on

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  13. Frequency dependence of the acoustic field generated from a spherical cavity transducer with open ends

    SciTech Connect

    Li, Faqi; Zeng, Deping; He, Min; Wang, Zhibiao E-mail: wangzhibiao@haifu.com.cn; Song, Dan; Lei, Guangrong; Lin, Zhou; Zhang, Dong E-mail: wangzhibiao@haifu.com.cn; Wu, Junru

    2015-12-15

    Resolution of high intensity focused ultrasound (HIFU) focusing is limited by the wave diffraction. We have developed a spherical cavity transducer with two open ends to improve the focusing precision without sacrificing the acoustic intensity (App Phys Lett 2013; 102: 204102). This work aims to theoretically and experimentally investigate the frequency dependence of the acoustic field generated from the spherical cavity transducer with two open ends. The device emits high intensity ultrasound at the frequency ranging from 420 to 470 kHz, and the acoustic field is measured by a fiber optic probe hydrophone. The measured results shows that the spherical cavity transducer provides high acoustic intensity for HIFU treatment only in its resonant modes, and a series of resonant frequencies can be choosen. Furthermore, a finite element model is developed to discuss the frequency dependence of the acoustic field. The numerical simulations coincide well with the measured results.

  14. Frequency dependence of the acoustic field generated from a spherical cavity transducer with open ends

    NASA Astrophysics Data System (ADS)

    Li, Faqi; Song, Dan; Zeng, Deping; Lin, Zhou; He, Min; Lei, Guangrong; Wu, Junru; Zhang, Dong; Wang, Zhibiao

    2015-12-01

    Resolution of high intensity focused ultrasound (HIFU) focusing is limited by the wave diffraction. We have developed a spherical cavity transducer with two open ends to improve the focusing precision without sacrificing the acoustic intensity (App Phys Lett 2013; 102: 204102). This work aims to theoretically and experimentally investigate the frequency dependence of the acoustic field generated from the spherical cavity transducer with two open ends. The device emits high intensity ultrasound at the frequency ranging from 420 to 470 kHz, and the acoustic field is measured by a fiber optic probe hydrophone. The measured results shows that the spherical cavity transducer provides high acoustic intensity for HIFU treatment only in its resonant modes, and a series of resonant frequencies can be choosen. Furthermore, a finite element model is developed to discuss the frequency dependence of the acoustic field. The numerical simulations coincide well with the measured results.

  15. Focused acoustic beam imaging of grain structure and local Young's modulus with Rayleigh and surface skimming longitudinal waves

    SciTech Connect

    Martin, R. W.; Sathish, S.; Blodgett, M. P.

    2013-01-25

    The interaction of a focused acoustic beam with materials generates Rayleigh surface waves (RSW) and surface skimming longitudinal waves (SSLW). Acoustic microscopic investigations have used the RSW amplitude and the velocity measurements, extensively for grain structure analysis. Although, the presence of SSLW has been recognized, it is rarely used in acoustic imaging. This paper presents an approach to perform microstructure imaging and local elastic modulus measurements by combining both RSW and SSLW. The acoustic imaging of grain structure was performed by measuring the amplitude of RSW and SSLW signal. The microstructure images obtained on the same region of the samples with RSW and SSLW are compared and the difference in the contrast observed is discussed based on the propagation characteristics of the individual surface waves. The velocity measurements are determined by two point defocus method. The surface wave velocities of RSW and SSLW of the same regions of the sample are combined and presented as average Young's modulus image.

  16. Fabrication, operation and flow visualization in surface-acoustic-wave-driven acoustic-counterflow microfluidics.

    PubMed

    Travagliati, Marco; Shilton, Richie; Beltram, Fabio; Cecchini, Marco

    2013-01-01

    Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains. PMID:24022515

  17. Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

    PubMed Central

    Travagliati, Marco; Shilton, Richie; Beltram, Fabio; Cecchini, Marco

    2013-01-01

    Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains. PMID:24022515

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

    NASA Astrophysics Data System (ADS)

    Tian, Miao; Kadri, Usama

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. Surface wave acoustics of granular packing under gravity

    NASA Astrophysics Data System (ADS)

    Clement, Eric; Bonneau, Lenaic; Andreotti, Bruno

    2009-06-01

    Due to the non-linearity of Hertzian contacts, the speed of sound in granular matter increases with pressure. For a packing under gravity and in the presence of a free surface, bulk acoustic waves cannot propagate due to the inherent refraction toward the surface (the mirage effect). Thus, only modes corresponding to surface waves (Raleigh-Hertz modes) are able to propagate the acoustic signal. First, based on a non-linear elasticity model, we describe the main features associated to these surface waves. We show that under gravity, a granular packing is from the acoustic propagation point of view an index gradient waveguide that selects modes of two distinct families i.e. the sagittal and transverse waves localized in the vicinity of the free surface. A striking feature of these surface waves is the multi-modal propagation: for both transverse and sagittal waves, we show the existence of a infinite but discrete series of propagating modes. In each case, we determine the mode shape and and the corresponding dispersion relation. In the case of a finite size system, a geometric waveguide is superimposed to the index gradient wave guide. In this later case, the dispersion relations are modified by the appearance of a cut-off frequency that scales with depth. The second part is devoted to an experimental study of surface waves propagating in a granular packing confined in a long channel. This set-up allows to tune a monomodal emission by taking advantage of the geometric waveguide features combined with properly designed emitters. For both sagittal and transverses waves, we were able to isolate a single mode (the fundamental one) and to plot the dispersion relation. This measurements agree well with the Hertzian scaling law as predicted by meanfield models. Furthermore, it allows us to determine quantitatively relations on the elastic moduli. However, we observe that our data yield a shear modulus abnormally weak when compared to several meanfield predictions.

  1. Surface wave acoustics of granular packing under gravity

    SciTech Connect

    Clement, Eric; Andreotti, Bruno; Bonneau, Lenaic

    2009-06-18

    Due to the non-linearity of Hertzian contacts, the speed of sound in granular matter increases with pressure. For a packing under gravity and in the presence of a free surface, bulk acoustic waves cannot propagate due to the inherent refraction toward the surface (the mirage effect). Thus, only modes corresponding to surface waves (Raleigh-Hertz modes) are able to propagate the acoustic signal. First, based on a non-linear elasticity model, we describe the main features associated to these surface waves. We show that under gravity, a granular packing is from the acoustic propagation point of view an index gradient waveguide that selects modes of two distinct families i.e. the sagittal and transverse waves localized in the vicinity of the free surface. A striking feature of these surface waves is the multi-modal propagation: for both transverse and sagittal waves, we show the existence of a infinite but discrete series of propagating modes. In each case, we determine the mode shape and and the corresponding dispersion relation. In the case of a finite size system, a geometric waveguide is superimposed to the index gradient wave guide. In this later case, the dispersion relations are modified by the appearance of a cut-off frequency that scales with depth. The second part is devoted to an experimental study of surface waves propagating in a granular packing confined in a long channel. This set-up allows to tune a monomodal emission by taking advantage of the geometric waveguide features combined with properly designed emitters. For both sagittal and transverses waves, we were able to isolate a single mode (the fundamental one) and to plot the dispersion relation. This measurements agree well with the Hertzian scaling law as predicted by meanfield models. Furthermore, it allows us to determine quantitatively relations on the elastic moduli. However, we observe that our data yield a shear modulus abnormally weak when compared to several meanfield predictions.

  2. Flow patterns and transport in Rayleigh surface acoustic wave streaming: combined finite element method and raytracing numerics versus experiments.

    PubMed

    Frommelt, Thomas; Gogel, Daniel; Kostur, Marcin; Talkner, Peter; Hänggi, Peter; Wixforth, Achim

    2008-10-01

    This work presents an approach for determining the streaming patterns that are generated by Rayleigh surface acoustic waves in arbitrary 3-D geometries by finite element method (FEM) simulations. An efficient raytracing algorithm is applied on the acoustic subproblem to avoid the unbearable memory demands and computational time of a conventional FEM acoustics simulation in 3-D. The acoustic streaming interaction is modeled by a body force term in the Stokes equation. In comparisons between experiments and simulated flow patterns, we demonstrate the quality of the proposed technique. PMID:18986877

  3. Synchronization of self-excited dust acoustic waves

    NASA Astrophysics Data System (ADS)

    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.

  4. Langasite Surface Acoustic Wave Sensors: Fabrication and Testing

    SciTech Connect

    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.

  5. Optimization of surface acoustic wave-based rate sensors.

    PubMed

    Xu, Fangqian; Wang, Wen; Shao, Xiuting; Liu, Xinlu; Liang, Yong

    2015-01-01

    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. PMID:26473865

  6. Optimization of Surface Acoustic Wave-Based Rate Sensors

    PubMed Central

    Xu, Fangqian; Wang, Wen; Shao, Xiuting; Liu, Xinlu; Liang, Yong

    2015-01-01

    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. PMID:26473865

  7. Propagation of three-dimensional electron-acoustic solitary waves

    SciTech Connect

    Shalaby, M.; El-Sherif, L. S.; El-Labany, S. K.; Sabry, R.

    2011-06-15

    Theoretical investigation is carried out for understanding the properties of three-dimensional electron-acoustic waves propagating in magnetized plasma whose constituents are cold magnetized electron fluid, hot electrons obeying nonthermal distribution, and stationary ions. For this purpose, the hydrodynamic equations for the cold magnetized electron fluid, nonthermal electron density distribution, and the Poisson equation are used to derive the corresponding nonlinear evolution equation, Zkharov-Kuznetsov (ZK) equation, in the small- but finite- amplitude regime. The ZK equation is solved analytically and it is found that it supports both solitary and blow-up solutions. It is found that rarefactive electron-acoustic solitary waves strongly depend on the density and temperature ratios of the hot-to-cold electron species as well as the nonthermal electron parameter. Furthermore, there is a critical value for the nonthermal electron parameter, which decides whether the electron-acoustic solitary wave's amplitude is decreased or increased by changing various plasma parameters. Importantly, the change of the propagation angles leads to miss the balance between the nonlinearity and dispersion; hence, the localized pulses convert to explosive/blow-up pulses. The relevance of this study to the nonlinear electron-acoustic structures in the dayside auroral zone in the light of Viking satellite observations is discussed.

  8. Synchronized photonic modulators driven by surface acoustic waves.

    PubMed

    Crespo-Poveda, A; Hey, R; Biermann, K; Tahraoui, A; Santos, P V; Gargallo, B; Muñoz, P; Cantarero, A; de Lima, M M

    2013-09-01

    Photonic modulators are one of the most important elements of integrated photonics. We have designed, fabricated, and characterized a tunable photonic modulator consisting of two 180°-dephased output waveguide channels, driven by a surface acoustic wave in the GHz frequency range built on (Al,Ga)As. Odd multiples of the fundamental driven frequency are enabled by adjusting the applied acoustic power. A good agreement between theory and experimental results is achieved. The device can be used as a building block for more complex integrated functionalities and can be implemented in several material platforms. PMID:24104040

  9. Modulational excitation of low-frequency dust acoustic waves in the Earth's lower ionosphere

    SciTech Connect

    Kopnin, S. I.; Popel, S. I.; Yu, M. Y.

    2007-04-15

    During the observation of Perseid, Leonid, Gemenid, and Orionid meteor showers, stable low-frequency lines in the frequency range of 20-60 Hz were recorded against the radio-frequency noise background. A physical mechanism for this effect is proposed, and it is established that the effect itself is related to the modulational interaction between electromagnetic and dust acoustic waves. The dynamics of the components of a complex (dusty) ionospheric plasma with dust produced from the evolution of meteoric material is described. The conditions for the existence of dust acoustic waves in the ionosphere are considered, and the waves are shown to dissipate energy mainly in collisions of neutral particles with charged dust grains. The modulational instability of electromagnetic waves in a complex (dusty) ionospheric plasma is analyzed and is found to be driven by the nonlinear Joule heating, the ponderomotive force, and the processes governing dust charging and dynamics. The conditions for the onset of the modulational instability of electromagnetic waves, as well as its growth rate and threshold, are determined for both daytime and nighttime. It is shown that low-frequency perturbations generated in the modulational interaction are related to dust acoustic waves.

  10. Confining capillary waves to control aerosol droplet size from surface acoustic wave nebulisation

    NASA Astrophysics Data System (ADS)

    Nazarzadeh, Elijah; Reboud, Julien; Wilson, Rab; Cooper, Jonathan M.

    Aerosols play a significant role in targeted delivery of medication through inhalation of drugs in a droplet form to the lungs. Delivery and targeting efficiencies are mainly linked to the droplet size, leading to a high demand for devices that can produce aerosols with controlled sizes in the range of 1 to 5 μm. Here we focus on enabling the control of the droplet size of a liquid sample nebulised using surface acoustic wave (SAW) generated by interdigitated transducers on a piezoelectric substrate (lithium niobate). The formation of droplets was monitored through a high-speed camera (600,000 fps) and the sizes measured using laser diffraction (Spraytec, Malvern Ltd). Results show a wide droplet size distribution (between 0.8 and 400 μm), while visual observation (at fast frame rates) revealed that the large droplets (>100 μm) are ejected due to large capillary waves (80 to 300 μm) formed at the free surface of liquid due to leakage of acoustic radiation of the SAWs, as discussed in previous literature (Qi et al. Phys Fluids, 2008). To negate this effect, we show that a modulated structure, specifically with feature sizes, typically 200 μm, prevents formation of large capillary waves by reducing the degrees of freedom of the system, enabling us to obtain a mean droplet size within the optimum range for drug delivery (<10 μm). This work was supported by an EPSRC grant (EP/K027611/1) and an ERC Advanced Investigator Award (340117-Biophononics).

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  12. Time-resolved coherent X-ray diffraction imaging of surface acoustic waves

    PubMed Central

    Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schülein, Florian J. R.; Krenner, Hubert J.; Wixforth, Achim; Salditt, Tim

    2014-01-01

    Time-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50 ps (pulse length). PMID:25294979

  13. Selective optical generation of a coherent acoustic nanocavity mode

    NASA Astrophysics Data System (ADS)

    Pascual Winter, M. F.; Rozas, G.; Jusserand, B.; Perrin, B.; Fainstein, A.; Vaccaro, P. O.; Saravanan, S.

    2007-04-01

    We report the first experimental evidence of selective generation of a confined acoustic mode in a Ga0.85In0.15As nanocavity enclosed by two Ga0.85In0.15As/AlAs phonon Bragg mirrors. Femtosecond pump-probe experiments reveal the generation of a cavity mode within the acoustic mini-gap of the mirrors, in addition to their folded acoustic modes. Selective generation of the confined mode alone is achievable for certain energies below the absorption of the quantum wells in the phonon mirrors. These energies are experimentally identified with the cavity spacer electronic transitions. The amplitude of the acoustic nanocavity mode can be controlled by detuning the excitation from the spacer transitions. The present work finds a direct interest in the seek of monochromatic MHz-THz acoustic sources.

  14. Nonlinear electron acoustic waves in presence of shear magnetic field

    SciTech Connect

    Dutta, Manjistha; Khan, Manoranjan; Ghosh, Samiran; Chakrabarti, Nikhil

    2013-12-15

    Nonlinear electron acoustic waves are studied in a quasineutral plasma in the presence of a variable magnetic field. The fluid model is used to describe the dynamics of two temperature electron species in a stationary positively charged ion background. Linear analysis of the governing equations manifests dispersion relation of electron magneto sonic wave. Whereas, nonlinear wave dynamics is being investigated by introducing Lagrangian variable method in long wavelength limit. It is shown from finite amplitude analysis that the nonlinear wave characteristics are well depicted by KdV equation. The wave dispersion arising in quasineutral plasma is induced by transverse magnetic field component. The results are discussed in the context of plasma of Earth's magnetosphere.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Diffraction of dust acoustic waves by a circular cylinder

    SciTech Connect

    Kim, S.-H.; Heinrich, J. R.; Merlino, R. L.

    2008-09-15

    The diffraction of dust acoustic (DA) waves around a long dielectric rod is observed using video imaging methods. The DA waves are spontaneously excited in a dusty plasma produced in a direct current glow discharge plasma. The rod acquires a negative charge that produces a coaxial dust void around it. The diameter of the void is the effective size of the 'obstacle' encountered by the waves. The wavelength of the DA waves is approximately the size of the void. The observations are considered in relation to the classical problem of the diffraction of sound waves from a circular cylinder, a problem first analyzed by Lord Rayleigh [Theory of Sound, 2nd ed. (MacMillan, London, 1896)].

  17. On-chip droplet production regimes using surface acoustic waves.

    PubMed

    Brenker, Jason C; Collins, David J; Van Phan, Hoang; Alan, Tuncay; Neild, Adrian

    2016-04-26

    Aqueous droplets suspended in an immiscible carrier fluid are a key tool in microfluidic chemical analysis platforms. The approaches for producing droplets in microfluidic devices can be divided into three general categories: batch emulsification, continuous production and tailored on-demand production. The major distinctions between each category are the rate of production and the degree of control over the droplet formation process in terms of the size and quantity. On-demand methods are highly desirable when, for example, small numbers or even single droplets of one sample type are required at a time. Here, we present a method for the on-demand production of femtolitre droplets, utilising a pressure source generated by high frequency surface acoustic waves (SAW). An increase in the continuous phase flow rate is enabled by a quasi-3D feature at the droplet production nozzle. A wide range of accessible flow rates permits the identification of different physical regimes in which droplets of different dimensions are produced. In the system investigated droplets measuring as little as 200 fl have been produced, ∼1/60th of the minimum volume previously reported. The experimental findings are supported by a numerical model which demonstrates the link between the number of droplets formed and the pulse length used. PMID:27045939

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

    SciTech Connect

    Fan, Ren-Hao; Peng, Ru-Wen; Huang, Xian-Rong; Wang, Mu

    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.

  19. Dispersion and mirror transmission characteristics of bulk acoustic wave resonators.

    PubMed

    Kokkonen, Kimmo; Pensala, Tuomas; Kaivola, Matti

    2011-01-01

    A heterodyne laser interferometer is used for a detailed study of the acoustic wave fields excited in a 932-MHz solidly mounted ZnO thin-film BAW resonator. The sample is manufactured on a glass substrate, which also allows direct measurement of the vibration fields from the bottom of the acoustic mirror. Vibration fields are measured both on top of the resonator and at the mirror-substrate interface in a frequency range of 350 to 1200 MHz. Plate wave dispersion diagrams are calculated from the experimental data in both cases and the transmission characteristics of the acoustic mirror are determined as a function of both frequency and lateral wave number. The experimental data are compared with 1-D and 2-D simulations to evaluate the validity of the modeling tools commonly used in mirror design. All the major features observed in the 1-D model are identified in the measured dispersion diagrams, and the mirror transmission characteristics predicted for the longitudinal waves, by both the 1-D and the 2-D models, match the measured values well. PMID:21244989

  20. Surface crack detection for Al plate using the surface acoustic waves and neural network identification

    NASA Astrophysics Data System (ADS)

    Guan, Jianfei; Shen, Zhonghua; Xu, Baiqiang; Lu, Jian; Ni, Xiaowu

    2005-01-01

    This paper utilized the Finite Element Method to investigate the transient scattering of Rayleigh wave by a surface crack in a plate. The incident wave models the guided waves generated by a pulsed line source laser irradiation on the top surface of the plate. The pulsed laser is assumed to be transient heat source, and the surface acoustic wave is calculated based on the thermoelastic theory. We have computed the different results of the Al plates with the varied depth surface-breaking crack, then attained the temporal characteristics of reflected waves and transmitted waves which are generated by the initial surface acoustic waves interacted with the surface breaking cracks with different depth. The artificial neural networks (ANN) are applied to establish the mapping relationship between the characteristic of the reflected waveform and the crack depth. The results of crack damage detection for Al plates show that the method developed in this paper can be applied to online structural damage detection and health monitoring for various industrial structures.

  1. Analysis of Measured and Simulated Supraglottal Acoustic Waves.

    PubMed

    Fraile, Rubén; Evdokimova, Vera V; Evgrafova, Karina V; Godino-Llorente, Juan I; Skrelin, Pavel A

    2016-09-01

    To date, although much attention has been paid to the estimation and modeling of the voice source (ie, the glottal airflow volume velocity), the measurement and characterization of the supraglottal pressure wave have been much less studied. Some previous results have unveiled that the supraglottal pressure wave has some spectral resonances similar to those of the voice pressure wave. This makes the supraglottal wave partially intelligible. Although the explanation for such effect seems to be clearly related to the reflected pressure wave traveling upstream along the vocal tract, the influence that nonlinear source-filter interaction has on it is not as clear. This article provides an insight into this issue by comparing the acoustic analyses of measured and simulated supraglottal and voice waves. Simulations have been performed using a high-dimensional discrete vocal fold model. Results of such comparative analysis indicate that spectral resonances in the supraglottal wave are mainly caused by the regressive pressure wave that travels upstream along the vocal tract and not by source-tract interaction. On the contrary and according to simulation results, source-tract interaction has a role in the loss of intelligibility that happens in the supraglottal wave with respect to the voice wave. This loss of intelligibility mainly corresponds to spectral differences for frequencies above 1500 Hz. PMID:26377510

  2. Acoustic wave absorption as a probe of dynamical geometrical response of fractional quantum Hall liquids

    NASA Astrophysics Data System (ADS)

    Yang, Kun

    2016-04-01

    We show that an acoustic crystalline wave gives rise to an effect similar to that of a gravitational wave to an electron gas. Applying this idea to a two-dimensional electron gas in the fractional quantum Hall regime, this allows for experimental study of its intra-Landau level dynamical response in the long-wavelength limit. To study such response we generalize Haldane's geometrical description of fractional quantum Hall states to situations where the external metric is time dependent. We show that such time-dependent metric (generated by acoustic wave) couples to collective modes of the system, including a quadrapolar mode at long wavelength, and magnetoroton at finite wavelength. Energies of these modes can be revealed in spectroscopic measurements, controlled by strain-induced Fermi velocity anisotropy. We argue that such geometrical probe provides a potentially highly useful alternative probe of quantum Hall liquids, in addition to the usual electromagnetic response.

  3. Optically tunable acoustic wave band-pass filter

    SciTech Connect

    Swinteck, N.; Lucas, P.; Deymier, P. A.

    2014-12-15

    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. TeO2 slow surface acoustic wave Bragg cell

    NASA Astrophysics Data System (ADS)

    Yao, Shi-Kay

    1991-08-01

    A newly discovered slow acoustic surface wave (SAW) on a (-110) cut TeO2 surface is reported focusing on its properties studied using a PC based numerical method. It is concluded that the slow SAW is rather tolerant to crystal surface orientation errors and has unusually deep penetration of its shear component into the thickness of substrate, about 47 wavelengths for a half amplitude point. The deep shear field is considered to be beneficial for surface acoustooptic interaction with free propagating focused laser beams. Rotation of the substrate about the z-axis makes it possible to adjust a slow SAW velocity with the potential advantage of trading acoustic velocity for less acoustic attenuation. Wider-bandwidth long signal processing time Bragg cells may be feasible utilizing this trade-off. The slow SAW device is characterized by an extremely low power consumption which might be useful for compact portable or avionics signal processing equipment applications.

  5. Surface Acoustic Waves on Piezoelectrics: The KGBS Connection

    NASA Astrophysics Data System (ADS)

    Hickernell, Fred S.

    2003-10-01

    In December of 1968 Jeffrey Bleustein of Yale University published an article in Applied Physics Letters predicting the existence of a new type of transverse surface acoustic wave that could propagate on the surface of a piezoelectric crystal. This was followed within 20 days by an article published in Soviet Physics JETP Letters by Yuri Gulyaev in January of 1969 predicting the same basic property. The wave took on the name Bleustein-Gulyaev or BG-wave, joining the names of Rayleigh, Love, Sezawa, and Stonely for distinct types of surface acoustic waves. But is there more to the story than this? Did Kagonov and Sklovskaya anticipate this development in a publication as early as 1966? Also, what about the work of Shimizu, Nakamura, and Ohta, who in April of 1969 published both theoretical and experimental verification of the existence of such a wave independent of the knowledge of the Bleustein and Gulyaev papers? This presentation explores the early roots and characteristics of what could be called the KGBS wave.

  6. Generation of instability waves at a leading edge

    NASA Technical Reports Server (NTRS)

    Goldstein, M. E.

    1982-01-01

    This paper describes the generation of instability waves downstream of a leading edge by an imposed upstream disturbance. Two cases are considered. The first is concerned with mean flows of the Blasius type wherein the instabilities are represented by Tollmien-Schlichting waves. It is shown that the latter are generated fairly far downstream of the edge and are the result of a wave length reduction process that tunes the free stream disturbances to the Tollmien-Schlichting wave length. The other case is concerned with inflectional, uni-directional, transversely sheared mean flows. Such idealized flows provide a fairly good local representation to the nearly parallel flows in jets. They can support inviscid instabilities of the Kelvin-Helmholtz type. The various mathematically permissible mechanisms that can couple these instabilities to the upstream disturbances are discussed. The results are compared to some acoustic measurements and conclusions are drawn about the generation of the instabilities in these flows.

  7. Comparison of Transmission Line Methods for Surface Acoustic Wave Modeling

    NASA Technical Reports Server (NTRS)

    Wilson, William; Atkinson, Gary

    2009-01-01

    Surface Acoustic Wave (SAW) technology is low cost, rugged, lightweight, extremely low power and can be used to develop passive wireless sensors. For these reasons, NASA is investigating the use of SAW technology for Integrated Vehicle Health Monitoring (IVHM) of aerospace structures. To facilitate rapid prototyping of passive SAW sensors for aerospace applications, SAW models have been developed. This paper reports on the comparison of three methods of modeling SAWs. The three models are the Impulse Response Method (a first order model), and two second order matrix methods; the conventional matrix approach, and a modified matrix approach that is extended to include internal finger reflections. The second order models are based upon matrices that were originally developed for analyzing microwave circuits using transmission line theory. Results from the models are presented with measured data from devices. Keywords: Surface Acoustic Wave, SAW, transmission line models, Impulse Response Method.

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

    NASA Technical Reports Server (NTRS)

    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.

  9. Angular spectrum approach for the computation of group and phase velocity surfaces of acoustic waves in anisotropic materials

    PubMed

    Pluta; Schubert; Jahny; Grill

    2000-03-01

    The decomposition of an acoustic wave into its angular spectrum representation creates an effective base for the calculation of wave propagation effects in anisotropic media. In this method, the distribution of acoustic fields is calculated in arbitrary planes from the superposition of the planar components with proper phase shifts. These phase shifts depend on the ratio of the distance between the planes to the normal component of the phase slowness vector. In anisotropic media, the phase shifts depend additionally on the changes of the slowness with respect to the direction of the propagation vector and the polarization. Those relations are obtained from the Christoffel equation. The method employing the fast Fourier transformation algorithm is especially suited for volume imaging in anisotropic media, based on holographic detection in transmission of acoustic waves generated by a point source. This technique is compared with measurements on crystals performed by phase-sensitive scanning acoustic microscopy. PMID:10829665

  10. Microfluidic integrated acoustic waving for manipulation of cells and molecules.

    PubMed

    Barani, Alireza; Paktinat, Hossein; Janmaleki, Mohsen; Mohammadi, Aminollah; Mosaddegh, Peiman; Fadaei-Tehrani, Alireza; Sanati-Nezhad, Amir

    2016-11-15

    Acoustophoresis with its simple and low-cost fabrication, rapid and localized fluid actuation, compatibility with microfluidic components, and biocompatibility for cellular studies, has been extensively integrated into microfluidics to provide on-chip microdevices for a variety of applications in biology, bioengineering and chemistry. Among different applications, noninvasive manipulation of cells and biomolecules are significantly important, which are addressed by acoustic-based microfluidics. Here in this paper, we briefly explain the principles and different configurations of acoustic wave and acoustic streaming for the manipulation of cells and molecules and overview its applications for single cell isolation, cell focusing and sorting, cell washing and patterning, cell-cell fusion and communication, and tissue engineering. We further discuss the application of acoustic-based microfluidic systems for the mixing and transport of liquids, manipulation of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) molecules, followed by explanation on the present challenges of acoustic-based microfluidics for the handling of cells and molecules, and highlighting the future directions. PMID:27262557

  11. Interaction of electromagnetic and acoustic waves in a stochastic atmosphere

    NASA Technical Reports Server (NTRS)

    Bhatnagar, N.; Peterson, A. M.

    1979-01-01

    In the Stanford radio acoustic sounding system (RASS) an electromagnetic signal is made to scatter from a moving acoustic pulse train. Under a Bragg-scatter condition maximum electromagnetic scattering occurs. The scattered radio signal contains temperature and wind information as a function of the acoustic-pulse position. In this investigation RASS performance is assessed in an atmosphere characterized by the presence of turbulence and mean atmospheric parameters. The only assumption made is that the electromagnetic wave is not affected by stochastic perturbations in the atmosphere. It is concluded that the received radio signal depends strongly on the intensity of turbulence for altitudes of the acoustic pulse greater than the coherence length of propagation. The effect of mean vertical wind and mean temperature on the strength of the received signal is also demonstrated to be insignificant. Mean horizontal winds, however, shift the focus of the reflected electromagnetic energy from its origin, resulting in a decrease in received signal level when a monostatic radio-frequency (RF) system is used. For a bistatic radar configuration with space diversified receiving antennas, the shifting of the acoustic pulse makes possible the remote measurement of the horizontal wind component.

  12. Impact of Acoustic Standing Waves on Structural Responses

    NASA Technical Reports Server (NTRS)

    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.

  13. R&D 100 Winner 2010: Acoustic Wave Biosensors

    ScienceCinema

    Larson, Richard; Branch, Darren; Edwards, Thayne

    2016-06-29

    The acoustic wave biosensor is innovative device that is a handheld, battery-powered, portable detection system capable of multiplex identification of a wide range of medically relevant pathogens and their biomolecular signatures ? viruses, bacteria, proteins, and DNA ? at clinically relevant levels. This detection occurs within minutes ? not hours ? at the point of care, whether that care is in a physician's office, a hospital bed, or at the scene of a biodefense or biomedical emergency.

  14. Application of guided acoustic waves to delamination detection

    NASA Technical Reports Server (NTRS)

    Sun, Keun J.

    1992-01-01

    Guided plate waves are able to interact with structural flaws such as delaminations and cracks due to their propagation properties highly sensitive to the thickness change in materials. A technique which employs an acoustic damper to probe the results of this interaction and then to locate flaws in a relatively short period of time is developed. With its technical advantages, this technique shows its potential application to large area structural integrity assessment.

  15. Surface acoustic wave probe implant for predicting epileptic seizures

    DOEpatents

    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.

  16. Space manufacturing of surface acoustic wave devices, appendix D

    NASA Technical Reports Server (NTRS)

    Sardella, G.

    1973-01-01

    Space manufacturing of transducers in a vibration free environment is discussed. Fabrication of the masks, and possible manufacturing of the surface acoustic wave components aboard a space laboratory would avoid the inherent ground vibrations and the frequency limitation imposed by a seismic isolator pad. The manufacturing vibration requirements are identified. The concepts of space manufacturing are analyzed. A development program for manufacturing transducers is recommended.

  17. Optimizing surface acoustic wave sensors for trace chemical detection

    SciTech Connect

    Frye, G.C.; Kottenstette, R.J.; Heller, E.J.

    1997-06-01

    This paper describes several recent advances for fabricating coated surface acoustic wave (SAW) sensors for applications requiring trace chemical detection. Specifically, we have demonstrated that high surface area microporous oxides can provide 100-fold improvements in SAW sensor responses compared with more typical polymeric coatings. In addition, we fabricated GaAs SAW devices with frequencies up to 500 MHz to provide greater sensitivity and an ideal substrate for integration with high-frequency electronics.

  18. Decay of transverse acoustic waves in a pulsed gas laser

    SciTech Connect

    Kulkarny, V.A.

    1980-11-01

    The long-term characteristics of transverse acoustic waves in the cavity of a pulsed gaseous laser were studied by analyzing them in a straight duct configuration with nonlinear techniques used in sonic boom problems. A decaying sawtooth waveform containing a shockwave reverberated in the cavity transverse to the flow direction. In the asymptotic decay, the relative pressure perturbation of the wave varies as the 2/5 power of the product of the relative overpressure from the pulse and the speed of sound in the gas.

  19. Volumetric measurements of a spatially growing dust acoustic wave

    SciTech Connect

    Williams, Jeremiah D.

    2012-11-15

    In this study, tomographic particle image velocimetry (tomo-PIV) techniques are used to make volumetric measurements of the dust acoustic wave (DAW) in a weakly coupled dusty plasma system in an argon, dc glow discharge plasma. These tomo-PIV measurements provide the first instantaneous volumetric measurement of a naturally occurring propagating DAW. These measurements reveal over the measured volume that the measured wave mode propagates in all three spatial dimensional and exhibits the same spatial growth rate and wavelength in each spatial direction.

  20. Numerical study of nonlinear full wave acoustic propagation

    NASA Astrophysics Data System (ADS)

    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.

  1. EXCITATION OF ACOUSTIC WAVES BY VORTICES IN THE QUIET SUN

    SciTech Connect

    Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A.

    2011-02-01

    The five-minute oscillations are one of the basic properties of solar convection. Observations show a mixture of a large number of acoustic wave fronts propagating from their sources. We investigate the process of acoustic waves excitation from the point of view of individual events, by using a realistic three-dimensional radiative hydrodynamic simulation of the quiet Sun. The results show that the excitation events are related to the dynamics of vortex tubes (or swirls) in intergranular lanes of solar convection. These whirlpool-like flows are characterized by very strong horizontal velocities (7-11 km s{sup -1}) and downflows ({approx}7 km s{sup -1}), and are accompanied by strong decreases of temperature, density, and pressure at the surface and 0.5-1 Mm below the surface. High-speed whirlpool flows can attract and capture other vortices. According to our simulation results the processes of vortex interaction, such as vortex annihilation, can cause excitation of acoustic waves on the Sun.

  2. Nonlinear progressive acoustic-gravity waves: Exact solutions

    NASA Astrophysics Data System (ADS)

    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

  3. Ion acoustic shock wave in collisional equal mass plasma

    NASA Astrophysics Data System (ADS)

    Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil

    2015-10-01

    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.

  4. Ion acoustic shock wave in collisional equal mass plasma

    SciTech Connect

    Adak, Ashish; Ghosh, Samiran; Chakrabarti, Nikhil

    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.

  5. Acoustic nonlinear periodic waves in pair-ion plasmas

    NASA Astrophysics Data System (ADS)

    Mahmood, Shahzad; Kaladze, Tamaz; Ur-Rehman, Hafeez

    2013-09-01

    Electrostatic acoustic nonlinear periodic (cnoidal) waves and solitons are investigated in unmagnetized pair-ion plasmas consisting of same mass and oppositely charged ion species with different temperatures. Using reductive perturbation method and appropriate boundary conditions, the Korteweg-de Vries (KdV) equation is derived. The analytical solutions of both cnoidal wave and soliton solutions are discussed in detail. The phase plane plots of cnoidal and soliton structures are shown. It is found that both compressive and rarefactive cnoidal wave and soliton structures are formed depending on the temperature ratio of positive and negative ions in pair-ion plasmas. In the special case, it is revealed that the amplitude of soliton may become larger than it is allowed by the nonlinear stationary wave theory which is equal to the quantum tunneling by particle through a potential barrier effect. The serious flaws in the earlier published results by Yadav et al., [PRE 52, 3045 (1995)] and Chawla and Misra [Phys. Plasmas 17, 102315 (2010)] of studying ion acoustic nonlinear periodic waves are also pointed out.

  6. RADIATIVE HYDRODYNAMIC SIMULATIONS OF ACOUSTIC WAVES IN SUNSPOTS

    SciTech Connect

    Bard, S.; Carlsson, M.

    2010-10-10

    We investigate the formation and evolution of the Ca II H line in a sunspot. The aim of our study is to establish the mechanisms underlying the formation of the frequently observed brightenings of small regions of sunspot umbrae known as 'umbral flashes'. We perform fully consistent NLTE radiation hydrodynamic simulations of the propagation of acoustic waves in sunspot umbrae and conclude that umbral flashes result from increased emission of the local solar material during the passage of acoustic waves originating in the photosphere and steepening to shock in the chromosphere. To quantify the significance of possible physical mechanisms that contribute to the formation of umbral flashes, we perform a set of simulations on a grid formed by different wave power spectra, different inbound coronal radiation, and different parameterized chromospheric heating. Our simulations show that the waves with frequencies in the range 4.5-7.0 mHz are critical to the formation of the observed blueshifts of umbral flashes while waves with frequencies below 4.5 mHz do not play a role despite their dominance in the photosphere. The observed emission in the Ca II H core between flashes only occurs in the simulations that include significant inbound coronal radiation and/or extra non-radiative chromospheric heating in addition to shock dissipation.

  7. Characteristics of acoustic gravity waves obtained from Dynasonde data

    NASA Astrophysics Data System (ADS)

    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.

  8. Excitation and detection of shear horizontal waves with electromagnetic acoustic transducers for nondestructive testing of plates

    NASA Astrophysics Data System (ADS)

    Ma, Qingzeng; Jiao, Jingpin; Hu, Ping; Zhong, Xi; Wu, Bin; He, Cunfu

    2014-03-01

    The fundamental shear horizontal(SH0) wave has several unique features that are attractive for long-range nondestructive testing(NDT). By a careful design of the geometric configuration, electromagnetic acoustic transducers(EMATs) have the capability to generate a wide range of guided wave modes, such as Lamb waves and shear-horizontal(SH) waves in plates. However, the performance of EMATs is influenced by their parameters. To evaluate the performance of periodic permanent magnet(PPM) EMATs, a distributed-line-source model is developed to calculate the angular acoustic field cross-section in the far-field. Numerical analysis is conducted to investigate the performance of such EMATs with different geometric parameters, such as period and number of magnet arrays, and inner and outer coil widths. Such parameters have a great influence on the directivity of the generated SH0 waves that arises mainly in the amplitude and width of both main and side lobes. According to the numerical analysis, these parameters are optimized to obtain better directivity. Optimized PPM EMATs are designed and used for NDT of strip plates. Experimental results show that the lateral boundary of the strip plate has no perceivable influence on SH0-wave propagation, thus validating their used in NDT. The proposed model predicts the radiation pattern of PPM EMATs, and can be used for their parameter optimization.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Guided wave opto-acoustic device

    DOEpatents

    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.

  11. Acoustic-radiation-force-induced shear wave propagation in cardiac tissue

    NASA Astrophysics Data System (ADS)

    Bouchard, Richard R.; Wolf, Patrick D.; Hsu, Stephen J.; Dumont, Douglas M.; Trahey, Gregg E.

    2009-02-01

    Shear wave elasticity imaging (SWEI) was employed to track acoustic radiation force (ARF)-induced shear waves in the myocardium of a beating heart. Shear waves were generated in and tracked through the myocardium of the left ventricular free wall (LVFW) in an in vivo heart that was exposed through a thoracotomy; matched studies were also preformed on an ex vivo myocardial specimen. Average shear wave velocities ranged from 2.22 to 2.53 m/s for the ex vivo specimen and 1.5 to 2.9 m/s (1.5-2.09 m/s during diastole; 2.9 m/s during systole) for in vivo specimens. Despite the known rotation of myocardial fiber orientation with tissue depth, there was no statistically significant shear wave velocity depth dependence observed in any of the experimental trials.

  12. Wave theory of turbulence in compressible media (acoustic theory of turbulence)

    NASA Technical Reports Server (NTRS)

    Kentzer, C. P.

    1975-01-01

    The generation and the transmission of sound in turbulent flows are treated as one of the several aspects of wave propagation in turbulence. Fluid fluctuations are decomposed into orthogonal Fourier components, with five interacting modes of wave propagation: two vorticity modes, one entropy mode, and two acoustic modes. Wave interactions, governed by the inhomogeneous and nonlinear terms of the perturbed Navier-Stokes equations, are modeled by random functions which give the rates of change of wave amplitudes equal to the averaged interaction terms. The statistical framework adopted is a quantum-like formulation in terms of complex distribution functions. The spatial probability distributions are given by the squares of the absolute values of the complex characteristic functions. This formulation results in nonlinear diffusion-type transport equations for the probability densities of the five modes of wave propagation.

  13. Feasibility of using nonlinear guided waves to measure acoustic nonlinearity of aluminum

    NASA Astrophysics Data System (ADS)

    Matlack, Kathryn H.; Kim, Jin-Yeon; Jacobs, Laurence J.; Qu, Jianmin

    2011-04-01

    This research investigates the feasibility of measuring acoustic nonlinearity in aluminum with different ultrasonic guided wave modes. Acoustic nonlinearity is manifested by generation of a second harmonic component in an originally monochromatic ultrasonic wave signal, and previous research has shown this correlates to an intrinsic material property. This parameter has been shown to increase with accumulated material damage - specifically in low- and high-cycle fatigue - prior to crack initiation, whereas other ultrasonic nondestructive evaluation (NDE) techniques measuring linear parameters are unable to detect damage prior to crack initiation. In structural components such as jet engines and aircraft structures subjected to fatigue damage, crack initiation does not occur until ~80% of a component's life. Thus, there is a need for structural health monitoring (SHM) techniques that can characterize material damage state prior to crack initiation, and therefore nonlinear ultrasonic techniques have the potential to be powerful NDE and SHM tools. Experimental results using Rayleigh and Lamb guided wave modes to measure acoustic nonlinearity in undamaged aluminum 6061 samples are presented, and a comparison of the efficiency of these modes to measure acoustic nonlinearity is given.

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

    SciTech Connect

    Andreev, Pavel A. Kuz'menkov, L. S.

    2015-03-15

    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.

  15. Separation of biological cells in a microfluidic device using surface acoustic waves (SAWs)

    NASA Astrophysics Data System (ADS)

    Ai, Ye; Marrone, Babetta L.

    2014-03-01

    In this study, a surface acoustic wave (SAW)-based microfluidic device has been developed to separate heterogeneous particle or cell mixtures in a continuous flow using acoustophoresis. The microfluidic device is comprised of two components, a SAW transducer and a microfluidic channel made of polydimethylsiloxane (PDMS). The SAW transducer was fabricated by patterning two pairs of interdigital electrodes on a lithium niobate (LiNbO3) piezoelectric substrate. When exciting the SAW transducer by AC signals, a standing SAW is generated along the cross-section of the channel. Solid particles immersed in the standing SAW field are accordingly pushed to the pressure node arising from the acoustic radiation force acting on the particles, referring to the acoustic particle-focusing phenomenon. Acoustic radiation force highly depends on the particle properties, resulting in different acoustic responses for different types of cells. A numerical model, coupling the piezoelectric effect in the solid substrate and acoustic pressure in the fluid, was developed to provide a better understanding of SAW-based particle manipulation. Separation of two types of fluorescent particles has been demonstrated using the developed SAW-based microfluidic device. An efficient separation of E. coli bacteria from peripheral blood mononuclear cell (PBMC) samples has also been successfully achieved. The purity of separated E. coli bacteria and separated PBMCs were over 95% and 91%, respectively, obtained by a flow cytometric analysis. The developed microfluidic device can efficiently separate E. coli bacteria from biological samples, which has potential applications in biomedical analysis and clinical diagnosis.

  16. Topics in Lagrangian and Hamiltonian fluid dynamics: Relabeling symmetry and ion-acoustic wave stability

    NASA Astrophysics Data System (ADS)

    Padhye, Nikhil Subhash

    1998-12-01

    Relabeling symmetries of the Lagranian action are found for the ideal, compressible fluid and magnetohydrodynamics (MHD). These give rise to conservation laws of potential vorticity (Ertel's theorem) and helicity in the ideal fluid, cross helicity in MHD, and a conservation law for an ideal fluid with three thermodynamic variables. The symmetry that gives rise to Ertel's theorem is generated by an infinite parameter group, and leads to a generalized Bianchi identity. The existence of a more general symmetry is also shown, with dependence on time and space derivatives of the fields, and corresponds to a family of conservation laws associated with the potential vorticity. In the Hamiltonian formalism, Casimir invariants of the noncanonical formulation are directly constructed from the symmetries of the reduction map from Lagrangian to Eulerian variables. Casimir invariants of MHD include a gauge-dependent family of invariants that incorporates magnetic helicity as a special case. Novel examples of finite dimensional, noncanonical Hamiltonian dynamics are also presented: the equations for a magnetic field line flow with a symmetry direction, and Frenet formulas that describe a curve in 3-space. In the study of Lyapunov stability of ion-acoustic waves, existence of negative energy perturbations is found at short wavelengths. The effect of adiabatic, ionic pressure on ion-acoustic waves is investigated, leading to explicit solitary and nonlinear periodic wave solutions for the adiabatic exponent γ = 3. In particular, solitary waves are found to exist at any wave speed above Mach number one, without an upper cutoff speed. Negative energy perturbations are found to exist despite the addition of pressure, which prevents the establishment of Lyapunov stability, however the stability of ion-acoustic waves is established in the KdV limit, in a manner far simpler than the proof of KdV soliton stability. It is also shown that the KdV free energy (Benjamin, 1972) is recovered

  17. Turbulence generated by a gas of electron acoustic solitons

    SciTech Connect

    Dubouloz, N.; Pottelette, R.; Malingre, M.; Treumann, R.A.

    1993-10-01

    The authors consider a gas of electron acoustic solitons propagating in a magnetized plasma, such as the auroral region. They show that such modes can exist, and propagate, and that the velocities and amplitudes of such waves, consistent with measured plasma density and temperature, are capable of explaining the high frequency part of the broadband electrostatic noise observed by the Viking satellite, which is in a spectral region forbidden to linear electrostatic waves.

  18. Flow velocity measurement with the nonlinear acoustic wave scattering

    SciTech Connect

    Didenkulov, Igor; Pronchatov-Rubtsov, Nikolay

    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

    NASA Astrophysics Data System (ADS)

    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. Synchronization of the dust acoustic wave under microgravity

    NASA Astrophysics Data System (ADS)

    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.

  1. Stability analysis for two-dimensional ion-acoustic waves in quantum plasmas

    SciTech Connect

    Seadawy, A. R.

    2014-05-15

    The quantum hydrodynamic model is applied to two-dimensional ion-acoustic waves in quantum plasmas. The two-dimensional quantum hydrodynamic model is used to obtain a deformed Kortewegde Vries (dKdV) equation by reductive perturbation method. By using the solution of auxiliary ordinary equations, a extended direct algebraic method is described to construct the exact solutions for nonlinear quantum dKdV equation. The present results are describing the generation and evolution of such waves, their interactions, and their stability.

  2. A method for the frequency control in time-resolved two-dimensional gigahertz surface acoustic wave imaging

    SciTech Connect

    Kaneko, Shogo; Tomoda, Motonobu; Matsuda, Osamu

    2014-01-15

    We describe an extension of the time-resolved two-dimensional gigahertz surface acoustic wave imaging based on the optical pump-probe technique with periodic light source at a fixed repetition frequency. Usually such imaging measurement may generate and detect acoustic waves with their frequencies only at or near the integer multiples of the repetition frequency. Here we propose a method which utilizes the amplitude modulation of the excitation pulse train to modify the generation frequency free from the mentioned limitation, and allows for the first time the discrimination of the resulted upper- and lower-side-band frequency components in the detection. The validity of the method is demonstrated in a simple measurement on an isotropic glass plate covered by a metal thin film to extract the dispersion curves of the surface acoustic waves.

  3. Modeling Nonlinear Acoustic Standing Waves in Resonators: Theory and Experiments

    NASA Technical Reports Server (NTRS)

    Raman, Ganesh; Li, Xiaofan; Finkbeiner, Joshua

    2004-01-01

    The overall goal of the cooperative research with NASA Glenn is to fundamentally understand, computationally model, and experimentally validate non-linear acoustic waves in enclosures with the ultimate goal of developing a non-contact acoustic seal. The longer term goal is to transition the Glenn acoustic seal innovation to a prototype sealing device. Lucas and coworkers are credited with pioneering work in Resonant Macrosonic Synthesis (RMS). Several Patents and publications have successfully illustrated the concept of Resonant Macrosonic Synthesis. To utilize this concept in practical application one needs to have an understanding of the details of the phenomenon and a predictive tool that can examine the waveforms produced within resonators of complex shapes. With appropriately shaped resonators one can produce un-shocked waveforms of high amplitude that would result in very high pressures in certain regions. Our goal is to control the waveforms and exploit the high pressures to produce an acoustic seal. Note that shock formation critically limits peak-to-peak pressure amplitudes and also causes excessive energy dissipation. Proper shaping of the resonator is thus critical to the use of this innovation.

  4. Finite Difference Numerical Modeling of Gravito-Acoustic Wave Propagation in a Windy and Attenuating Atmosphere

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The acoustic and gravity waves propagating in the planetary atmospheres have been studied intensively as markers of specific phenomena (tectonic events, explosions) or as contributors to the atmosphere dynamics. To get a better understanding of the physic behind these dynamic processes, both acoustic and gravity waves propagation should be modeled in an attenuating and windy 3D atmosphere from the ground to the upper thermosphere. Thus, In order to provide an efficient numerical tool at the regional or the global scale a high order finite difference time domain (FDTD) approach is proposed that relies on the linearized compressible Navier-Stokes equations (Landau 1959) with non constant physical parameters (density, viscosities and speed of sound) and background velocities (wind). One significant benefit from this code is its versatility. Indeed, it handles both acoustic and gravity waves in the same simulation that enables one to observe correlations between the two. Simulations will also be performed on 2D/3D realistic cases such as tsunamis in a full MSISE-00 atmosphere and gravity-wave generation through atmospheric explosions. Computations are validated by comparison to well-known analytical solutions based on dispersion relations in specific benchmark cases (atmospheric explosion and bottom displacement forcing).

  5. On waves in gases. Part I: Acoustics of jets, turbulence, and ducts

    NASA Astrophysics Data System (ADS)

    Campos, L. M. B. C.

    1986-01-01

    This review on some aspects of waves in gases concentrates first (Part I) on modern research in the acoustics of fluids at rest or in steady or turbulent motion, in free space, in the presence of obstacles, or in ducts. The study of sound, for which the sole restoring force is pressure, will be extended in a later paper (Part II) to include the other three restoring forces, namely, gravity, electromagnetic, and Coriolis forces, leading to current research on internal, magnetic, and inertial waves and their couplings. The Introduction at the beginning of Part I, and the discussion at the end of Part II, concern all four types of waves in gases, and their relevance in physics and engineering. In Part I, the following areas of acoustics are addressed: the generation of noise by turbulence, inhomogeneities or bubbles, in natural and engineering flows, e.g., wind or jets; the scattering of sound by interfaces and diffraction by turbulence, and their effects on spectral and directional redistribution of energy; propagation in ducts, without or with mean flow, e.g., the horns of musical instruments and loudspeakers, and inlets and exhausts of engines; the effects of dissipation and nonlinearity on waves, e.g., in laboratory and engineering shock tubes, and in geophysical and astrophysical conditions. Underlying these topics is the interaction of acoustics with manking, ranging from the processes of human hearing and speech to the reproduction of desirable sounds (music) and reduction of undesirable sounds (noise).

  6. Dust acoustic solitary waves in a quantum plasma

    SciTech Connect

    Ali, S.; Shukla, P.K.

    2006-02-15

    By employing one-dimensional quantum hydrodynamic (QHD) model for a three species quantum plasma, nonlinear properties of dust acoustic solitary waves are studied. For this purpose a Korteweg-de Vries (KdV) equation is derived, incorporating quantum corrections. The quantum mechanical effects are also examined numerically both on the profiles of the amplitude and the width of dust acoustic solitary waves. It is found that the amplitude remains constant but the width shrinks for different values of a dimensionless electron quantum parameter H{sub e}={radical}((Z{sub d0}({Dirac_h}/2{pi}){sup 2}{omega}{sub pd}{sup 2})/m{sub e}m{sub d}C{sub d}{sup 4}), where Z{sub d0} is the dust charge state, ({Dirac_h}/2{pi}) is the Planck constant divided by 2{pi}, {omega}{sub pd} is the dust plasma frequency, m{sub e} (m{sub d}) is the electron (dust) mass, and C{sub d} is the dust acoustic speed.

  7. Longitudinal elastic wave propagation characteristics of inertant acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2009-08-01

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

  9. Multilayer magnetostrictive structure based surface acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Talbi, A.; Tiercelin, N.; Bou Matar, O.

    2014-03-01

    This study addresses the experimental and theoretical investigations of guided elastic waves propagation in piezo-magnetic multi-layered structure. The structure is composed of a 20×TbCo2(5nm)/FeCo(5nm) nanostructured multi-layer deposited between two Aluminum (Al) Inter-Digitals Transducers forming a surface acoustic wave delay line, on a Y-cut LiNbO3 substrate. We compare the calculated and measured phase velocity variation under the action of the external magnetic field orientation and magnitude. We find quantitative agreement between the measured and modeled phase velocity shift for all external magnetic field configurations (hard axis and easy axis) and for different shape modes of elastic waves at their first and third harmonic operation frequencies. The shear horizontal mode exhibits a maximum phase velocity shift close to 20% for a ratio close to 1 between magneto-elastic film thickness and wavelength.

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

    SciTech Connect

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

    2013-01-01

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

  11. Determination of particle size distributions from acoustic wave propagation measurements

    SciTech Connect

    Spelt, P.D.; Norato, M.A.; Sangani, A.S.; Tavlarides, L.L.

    1999-05-01

    The wave equations for the interior and exterior of the particles are ensemble averaged and combined with an analysis by Allegra and Hawley [J. Acoust. Soc. Am. {bold 51}, 1545 (1972)] for the interaction of a single particle with the incident wave to determine the phase speed and attenuation of sound waves propagating through dilute slurries. The theory is shown to compare very well with the measured attenuation. The inverse problem, i.e., the problem of determining the particle size distribution given the attenuation as a function of frequency, is examined using regularization techniques that have been successful for bubbly liquids. It is shown that, unlike the bubbly liquids, the success of solving the inverse problem is limited since it depends strongly on the nature of particles and the frequency range used in inverse calculations. {copyright} {ital 1999 American Institute of Physics.}

  12. Piezoelectric tube rotation effect owing to surface acoustic wave excitation

    NASA Astrophysics Data System (ADS)

    Biryukov, Sergey V.; Sotnikov, Andrei; Schmidt, Hagen

    2016-03-01

    It is shown experimentally that a macroscopic cylindrical solid shaped like a piezoelectric tube can be rotated due to the excitation of surface acoustic waves (SAWs) with different amplitudes propagating in opposite directions along the solid's surface. A unidirectional SAW transducer covering the whole cylindrical surface has been used for ac voltage excitation of waves with unequal amplitudes in both directions. The pattern of such a transducer consists of a periodic comb structure with two electrodes of different width per period. An external torque is not applied to the tube and, from the outside, its movement looks like a motion under the action of an internal force. The observed mechanical response of the piezoelectric cylindrical tube to excitation of waves is due to an angular momentum of SAWs, the value of which has been directly calculated from experimental results.

  13. Excitation of Ion Acoustic Waves in Confined Plasmas with Untrapped Electrons

    NASA Astrophysics Data System (ADS)

    Schamis, Hanna; Dow, Ansel; Carlsson, Johan; Kaganovich, Igor; Khrabrov, Alexander

    2015-11-01

    Various plasma propulsion devices exhibit strong electron emission from the walls either as a result of secondary processes or due to thermionic emission. To understand the electron kinetics in plasmas with strong emission, we have performed simulations using a reduced model with the LSP particle-in-cell code. This model aims to show the instability generated by the electron emission, in the form of ion acoustic waves near the sheath. It also aims to show the instability produced by untrapped electrons that propagate across the plasma, similarly to a beam, and can drive ion acoustic waves in the plasma bulk. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No.DE-AC02-09CH11466.

  14. Imaging of transient surface acoustic waves by full-field photorefractive interferometry

    SciTech Connect

    Xiong, Jichuan; Xu, Xiaodong E-mail: christ.glorieux@fys.kuleuven.be; Glorieux, Christ E-mail: christ.glorieux@fys.kuleuven.be; Matsuda, Osamu; Cheng, Liping

    2015-05-15

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz.

  15. On the generation of double layers from ion- and electron-acoustic instabilities

    NASA Astrophysics Data System (ADS)

    Fu, Xiangrong; Cowee, Misa M.; Gary, S. Peter; Winske, Dan

    2016-03-01

    A plasma double layer (DL) is a nonlinear electrostatic structure that carries a uni-polar electric field parallel to the background magnetic field due to local charge separation. Past studies showed that DLs observed in space plasmas are mostly associated with the ion acoustic instability. Recent Van Allen Probes observations of parallel electric field structures traveling much faster than the ion acoustic speed have motivated a computational study to test the hypothesis that a new type of DLs—electron acoustic DLs—generated from the electron acoustic instability are responsible for these electric fields. Nonlinear particle-in-cell simulations yield negative results, i.e., the hypothetical electron acoustic DLs cannot be formed in a way similar to ion acoustic DLs. Linear theory analysis and the simulations show that the frequencies of electron acoustic waves are too high for ions to respond and maintain charge separation required by DLs. However, our results do show that local density perturbations in a two-electron-component plasma can result in unipolar-like electric field structures that propagate at the electron thermal speed, suggesting another potential explanation for the observations.

  16. Acoustic Aspects of Photoacoustic Signal Generation and Detection in Gases

    NASA Astrophysics Data System (ADS)

    Miklós, A.

    2015-09-01

    In this paper photoacoustic signal generation and detection in gases is investigated and discussed from the standpoint of acoustics. Four topics are considered: the effect of the absorption-desorption process of modulated and pulsed light on the heat power density released in the gas; the generation of the primary sound by the released heat in an unbounded medium; the excitation of an acoustic resonator by the primary sound; and finally, the generation of the measurable PA signal by a microphone. When light is absorbed by a molecule and the excess energy is relaxed by collisions with the surrounding molecules, the average kinetic energy, thus also the temperature of an ensemble of molecules (called "particle" in acoustics) will increase. In other words heat energy is added to the energy of the particle. The rate of the energy transfer is characterized by the heat power density. A simple two-level model of absorption-desorption is applied for describing the heat power generation process for modulated and pulsed illumination. Sound generation by a laser beam in an unbounded medium is discussed by means of the Green's function technique. It is shown that the duration of the generated sound pulse depends mostly on beam geometry. A photoacoustic signal is mostly detected in a photoacoustic cell composed of acoustic resonators, buffers, filters, etc. It is not easy to interpret the measured PA signal in such a complicated acoustic system. The acoustic response of a PA detector to different kinds of excitations (modulated cw, pulsed, periodic pulse train) is discussed. It is shown that acoustic resonators respond very differently to modulated cw excitation and to excitation by a pulse train. The microphone for detecting the PA signal is also a part of the acoustic system; its properties have to be taken into account by the design of a PA detector. The moving membrane of the microphone absorbs acoustic energy; thus, it may influence the resonance frequency and

  17. Scattering of acoustic evanescent waves by circular cylinders: Partial wave series solution

    NASA Astrophysics Data System (ADS)

    Marston, Philip L.

    2002-05-01

    Evanescent acoustical waves occur in a variety of situations such as when sound is incident on a fluid interface beyond the critical angle and when flexural waves on a plate are subsonic with respect to the surrounding fluid. The scattering by circular cylinders at normal incidence was calculated to give insight into the consequences on the scattering of the evanescence of the incident wave. To analyze the scattering, it is necessary to express the incident wave using a modified expansion involving cylindrical functions. For plane evanescent waves, the expansion becomes a double summation with products of modified and ordinary Bessel functions. The resulting modified series is found for the scattering by a fluid cylinder in an unbounded medium. The perfectly soft and rigid cases are also examined. Unlike the case of an ordinary incident wave, the counterpropagating partial waves of the same angular order have unequal magnitudes when the incident wave is evanescent. This is a consequence of the exponential dependence of the incident wave amplitude on the transverse coordinate. The associated exponential dependence of the scattering on the location of a scatterer was previously demonstrated [T. J. Matula and P. L. Marston, J. Acoust. Soc. Am. 93, 1192-1195 (1993)].

  18. High-efficiency shock-wave generator for extracorporeal lithotripsy.

    PubMed

    Broyer, P; Cathignol, D; Theillère, Y; Mestas, J L

    1996-09-01

    In extracorporeal lithotripsy, the electro-acoustic efficiency of electrohydraulic generators is limited by the inductance of the electrical discharge circuit. A new shock-wave generator is described that uses a coaxial discharge line enabling electro-acoustic efficiency to be greatly increased. The line is built using a para-electric ceramic with a relative dielectric constant of 1700, manufactured for use in high-voltage impulse mode. A coaxial spark gap, with minimal inductance, has been developed to obtain the triggered breakdown of the discharge line. Shock waves are created with a coaxial electrode plugged directly into the spark gap and immersed in an electrolyte of degassed saline. Electrode gap and electrolyte resistivity are adjusted to match the resistivity of the electrolyte volume between the underwater electrodes to the characteristic impedance of the line. The discharge line generates in the medium a rectangular current pulse with an amplitude of about 6000 A and a rise time of 50 ns. Compared with conventional generators, measurements of the expansive peak pressure pulse show an increase of 105% at 10 kV, 86.5% at 12 kV and 34.5% at 14 kV charging voltage. Electro-acoustic efficiency is found to be 11% instead of 5.5% for a conventional discharge circuit. PMID:8945854

  19. Visualization of Surface Acoustic Waves in Thin Liquid Films

    PubMed Central

    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

  20. Ultrahigh Q Bulk Acoustic Wave Cavities at the Quantum Limit

    NASA Astrophysics Data System (ADS)

    Tobar, Michael; Goryachev, Maxim; Ivanov, Eugene; van Kann, Frank; Galliou, Serge

    2015-03-01

    A Fabry-Perot cavity is an optical resonator, which can store photons for milliseconds and enhance interaction between light and matter. The acoustics analogue (phonon trapping), is the Bulk Acoustic Wave device (in thin film or crystal lattice). Measurements provide the ultimate material loss regimes, minimizing clamping losses and achieving record high Q.f products, allowing observation of various loss mechanisms such as Landau-Rumer, phonon-phonon dissipation and Rayleigh phonon scattering, as well as previously non-observed non-linear effects. This presentation will summarize our recent work towards cooling such modes to the ground state and operating the device at the Quantum Limit. This includes the first measurements of the Nyquist noise near at 4K, as well as details on using such devices to test fundamental physics. Funded by ARC Grant No. CE110001013.

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

    PubMed

    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

  2. Absorption of surface acoustic waves by topological insulator thin films

    SciTech Connect

    Li, L. L.; Xu, W.

    2014-08-11

    We present a theoretical study on the absorption of the surface acoustic waves (SAWs) by Dirac electrons in topological insulator (TI) thin films (TITFs). We find that due to momentum and energy conservation laws, the absorption of the SAWs in TITFs can only be achieved via intra-band electronic transitions. The strong absorption can be observed up to sub-terahertz frequencies. With increasing temperature, the absorption intensity increases significantly and the cut-off frequency is blue-shifted. More interestingly, we find that the absorption of the SAWs by the TITFs can be markedly enhanced by the tunable subgap in the Dirac energy spectrum of the TI surface states. Such a subgap is absent in conventional two-dimensional electron gases (2DEGs) and in the gapless Dirac 2DEG such as graphene. This study is pertinent to the exploration of the acoustic properties of TIs and to potential application of TIs as tunable SAW devices working at hypersonic frequencies.

  3. Visualization of Surface Acoustic Waves in Thin Liquid Films

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  4. Defect states of acoustic waves in a two-dimensional lattice of solid cylinders

    SciTech Connect

    Sigalas, M.M.

    1998-09-01

    Using the plane-wave expansion method, we study the propagation of acoustic waves through two-dimensional (2D) periodic composites consisting of solid cylinders in air. Defect in those structures create localized states inside the band gaps. We study both single and line defects. Line defects can act as a waveguide for acoustic waves while single defects can be used as acoustical filters. {copyright} {ital 1998 American Institute of Physics.}

  5. Cylindrical and spherical ion acoustic waves in a plasma with nonthermal electrons and warm ions

    SciTech Connect

    Sahu, Biswajit; Roychoudhury, Rajkumar

    2005-05-15

    Using the reductive perturbation technique, nonlinear cylindrical and spherical Korteweg-de Vries (KdV) and modified KdV equations are derived for ion acoustic waves in an unmagnetized plasma consisting of warm adiabatic ions and nonthermal electrons. The effects of nonthermally distributed electrons on cylindrical and spherical ion acoustic waves are investigated. It is found that the nonthermality has a very significant effect on the nature of ion acoustic waves.

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

    PubMed

    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

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

    PubMed Central

    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

  8. PHENOMENOLOGICAL STUDY OF INTERACTION BETWEEN SOLAR ACOUSTIC WAVES AND SUNSPOTS FROM MEASURED SCATTERED WAVEFUNCTIONS

    SciTech Connect

    Yang, Ming-Hsu; Chou, Dean-Yi; Liang, Zhi-Chao; Zhao Hui

    2012-08-10

    The solar acoustic waves around a sunspot are modified because of the interaction with the sunspot. The interaction can be viewed as that the sunspot, excited by the incident wave, generates the scattered wave, and the scattered wave is added to the incident wave to form the total wave around the sunspot. We define an interaction parameter, which could be complex, describing the interaction between the acoustic waves and the sunspot. The scattered wavefunction on the surface can be expressed as a two-dimensional integral of the product of the Green's function, the wavefunction, and the two-dimensional interaction parameter over the sunspot area for the Born approximation of different orders. We assume a simple model for the two-dimensional interaction parameter distribution: its absolute value is axisymmetric with a Gaussian distribution and its phase is a constant. The measured scattered wavefunctions of various modes for NOAAs 11084 and 11092 are fitted to the theoretical scattered wavefunctions to determine the three model parameters, magnitude, Gaussian radius, and phase, for the Born approximation of different orders. The three model parameters converge to some values at high-order Born approximations. The result of the first-order Born approximation is significantly different from the convergent value in some cases. The rate of convergence depends on the sunspot size and wavelength. It converges more rapidly for the smaller sunspot and longer wavelength. The magnitude increases with mode frequency and degree for each radial order. The Gaussian radius is insensitive to frequency and degree. The spatial range of the interaction parameter is greater than that of the continuum intensity deficit, but smaller than that of the acoustic power deficit of the sunspot. The phase versus phase speed falls into a small range. This suggests that the phase could be a function phase speed. NOAAs 11084 and 11092 have a similar magnitude and phase, although the ratio of their

  9. Cell separation using tilted-angle standing surface acoustic waves

    PubMed Central

    Ding, Xiaoyun; Peng, Zhangli; Lin, Sz-Chin Steven; Geri, Michela; Li, Sixing; Li, Peng; Chen, Yuchao; Dao, Ming; Suresh, Subra; Huang, Tony Jun

    2014-01-01

    Separation of cells is a critical process for studying cell properties, disease diagnostics, and therapeutics. Cell sorting by acoustic waves offers a means to separate cells on the basis of their size and physical properties in a label-free, contactless, and biocompatible manner. The separation sensitivity and efficiency of currently available acoustic-based approaches, however, are limited, thereby restricting their widespread application in research and health diagnostics. In this work, we introduce a unique configuration of tilted-angle standing surface acoustic waves (taSSAW), which are oriented at an optimally designed inclination to the flow direction in the microfluidic channel. We demonstrate that this design significantly improves the efficiency and sensitivity of acoustic separation techniques. To optimize our device design, we carried out systematic simulations of cell trajectories, matching closely with experimental results. Using numerically optimized design of taSSAW, we successfully separated 2- and 10-µm-diameter polystyrene beads with a separation efficiency of ∼99%, and separated 7.3- and 9.9-µm-polystyrene beads with an efficiency of ∼97%. We illustrate that taSSAW is capable of effectively separating particles–cells of approximately the same size and density but different compressibility. Finally, we demonstrate the effectiveness of the present technique for biological–biomedical applications by sorting MCF-7 human breast cancer cells from nonmalignant leukocytes, while preserving the integrity of the separated cells. The method introduced here thus offers a unique route for separating circulating tumor cells, and for label-free cell separation with potential applications in biological research, disease diagnostics, and clinical practice. PMID:25157150

  10. Effect of tidal internal wave fields on shallow water acoustic propagation

    NASA Astrophysics Data System (ADS)

    Lin, Ju; Wang, Huan; Sun, Junping

    2010-09-01

    Internal waves are one of the most pronounced oceanic phenomenons to the oceanographer. During past decades much effort has been made to investigate the effect of internal waves on shallow water acoustic propagation. Even though many field observations, such as SWARM '95, have provided fruitful information about the relation between internal waves and acoustic propagation, it is necessary to conduct more numerical simulations due to their extensive feasibility. In this study, the shallow water internal wave environment is constructed by using a non-hydrostatic ocean model, the open boundary forcing is set by considering single or several internal wave modes at the M2 tidal frequency. In order to show the mode coupling caused by the internal wave field more clearly, the acoustic starting field with different single normal modes is adopted. The acoustic simulation can be used to check whether a specific combination of internal wave modes is related to the mode coupling, and which mode pair will be affected. The combination of internal wave modes can be separated into several groups. Even though the internal wave fields are different among every case in each group, the acoustic field structure and the mode coupling are similar. Different acoustic normal mode coupling occurs due to the different combinations of internal wave mode forcing. When the parameters of internal wave mode are modified gently, the acoustic mode coupling becomes quite different. It is interesting and important to investigate the sensitivity of acoustic fields to the variability of the internal mode combination.

  11. Towards field and laboratory experiments with ocean acoustic-gravity waves

    NASA Astrophysics Data System (ADS)

    Oliveira, Tiago; Kadri, Usama; Lin, Ying-Tsong; Morozov, Andrey

    2016-04-01

    Acoustic-gravity waves (AGWs) can be generated in the ocean by mechanical energy transfer from the Earth's crust (e.g. earthquakes or volcanoes) and by energy transfer occurring at the water surface (e.g. interaction of opposing gravity waves, ice-quakes or localized pressure changes). Recent theoretical studies shed light on the underlying physics of the generation and propagation of AGWs in the ocean. However, these theories are yet to be verified further with very challenging field experiments due to the associated low frequency signals required, and ambient disturbances involved. Here, we present a unique setup of field experiments and large scale laboratory tests to verify the main physical properties of AGWs in ocean generated by different types of sources. We also present a novel methodology to generate and measure AGWs in the ocean.

  12. Inhomogeneous Radiation Boundary Conditions Simulating Incoming Acoustic Waves for Computational Aeroacoustics

    NASA Technical Reports Server (NTRS)

    Tam, Christopher K. W.; Fang, Jun; Kurbatskii, Konstantin A.

    1996-01-01

    A set of nonhomogeneous radiation and outflow conditions which automatically generate prescribed incoming acoustic or vorticity waves and, at the same time, are transparent to outgoing sound waves produced internally in a finite computation domain is proposed. This type of boundary condition is needed for the numerical solution of many exterior aeroacoustics problems. In computational aeroacoustics, the computation scheme must be as nondispersive ans nondissipative as possible. It must also support waves with wave speeds which are nearly the same as those of the original linearized Euler equations. To meet these requirements, a high-order/large-stencil scheme is necessary The proposed nonhomogeneous radiation and outflow boundary conditions are designed primarily for use in conjunction with such high-order/large-stencil finite difference schemes.

  13. Evaluation of the resolution of a metamaterial acoustic leaky wave antenna.

    PubMed

    Naify, Christina J; Rogers, Jeffery S; Guild, Matthew D; Rohde, Charles A; Orris, Gregory J

    2016-06-01

    Acoustic antennas have long been utilized to directionally steer acoustic waves in both air and water. Typically, these antennas are comprised of arrays of active acoustic elements, which are electronically phased to steer the acoustic profile in the desired direction. A new technology, known as an acoustic leaky wave antenna (LWA), has recently been shown to achieve directional steering of acoustic waves using a single active transducer coupled to a transmission line passive aperture. The LWA steers acoustic energy by preferential coupling to an input frequency and can be designed to steer from backfire to endfire, including broadside. This paper provides an analysis of resolution as a function of both input frequency and antenna length. Additionally, the resolution is compared to that achieved using an array of active acoustic elements. PMID:27369149

  14. Quantum corrections to nonlinear ion acoustic wave with Landau damping

    SciTech Connect

    Mukherjee, Abhik; Janaki, M. S.; Bose, Anirban

    2014-07-15

    Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to the presence of Landau damping terms has been calculated assuming the Landau damping parameter α{sub 1}=√(m{sub e}/m{sub i}) to be of the same order of the quantum parameter Q=ℏ{sup 2}/(24m{sup 2}c{sub s}{sup 2}L{sup 2}). The amplitude is shown to decay very slowly with time as determined by the quantum factor Q.

  15. Adaptive laser array-receivers for acoustic waves detection

    NASA Astrophysics Data System (ADS)

    Tuovinen, Hemmo; Murray, Todd W.; Krishnaswamy, Sridhar

    2000-05-01

    Interferometric detection systems typically use a single focused laser point receiver for the detection of acoustic waves. In some cases, where optical damage of the structure is of concern, it may be advantageous to distribute the detection laser energy over an area. This can be done, for example, by using a point-array or a line-array probe. Other advantages of an array receiver include directional sensitivity and frequency selectivity. It is important to notice that laser-array reception is possible only with self-referential interferometers. In this paper adaptive array interferometric detection schemes, which are based on wave mixing in photorefractive bismuth silicate crystal, are described. An adaptive narrow-band laser array receiver of surface acoustic waves is demonstrated. The interferometer is also configured as a linearly frequency modulated (chirped) array receiver. The chirped receiver, when excited with a similarly chirped ultrasonic source, allows pulse compression of the ultrasonic signal thus maintaining high temporal resolution. The signal-to-noise ratio for the different array detection schemes are determined and compared. Several applications of laser-array reception are presented.

  16. The evaluation and control of acoustical standing waves1

    PubMed Central

    Krasnegor, Norman A.; Hodos, William

    1974-01-01

    Calibration of a standard pigeon box subsequently modified for use as an acoustical chamber in a frequency discrimination experiment revealed that the enclosure was not acoustically “flat”. Standing waves were detected at each of the six frequencies measured. To ascertain whether the maximum standing waves recorded (3.0 dB) could serve as an added or alternative cue for pigeons tested in the chamber on a frequency discrimination problem, pure-tone intensity difference thresholds were determined for two pigeons at 1.0, 2.0, and 3.0 KHz. The results of the experiment indicated that the smallest intensity difference detectable was 10.0 dB, a value that was 7.0 dB above the maximum standing wave measured in the box. These data suggest that the modified pigeon chamber is suitable to test pure-tone frequency discriminations in pigeons in the range of 1.0 to 3.0 KHz. PMID:16811783

  17. Effect of strong coupling on dust acoustic waves and instabilities

    SciTech Connect

    Rosenberg, M. Kalman, G.

    1998-10-01

    The presence of charged dust in a plasma can lead to very low frequency dust acoustic waves and instabilities. In certain laboratory plasmas the dust is strongly coupled, as characterized by the condition {Gamma}{sub d}=Q{sub d}{sup 2} exp({minus}d/{lambda}{sub D})/dT{sub d}{ge}1, where Q{sub d} is the dust charge, {ital d} is the intergrain spacing, T{sub d} is the dust thermal energy, and {lambda}{sub D} is the plasma screening length. When the dust is strongly coupled, the spatial correlation of the grains can affect the dispersion relation of these waves. We review our recent work [1] on the dispersion properties of dust acoustic waves in the strongly coupled (liquid) phase in a dusty plasma, including also the effects of dust-neutral collisions. We then discuss a preliminary analysis of the effect of strong dust coupling on an ion dust two-stream instability in a collisional dusty plasma. Applications to laboratory dusty plasmas are discussed. {copyright} {ital 1998 American Institute of Physics.}

  18. Effect of strong coupling on dust acoustic waves and instabilities

    SciTech Connect

    Rosenberg, M.; Kalman, G.

    1998-10-21

    The presence of charged dust in a plasma can lead to very low frequency dust acoustic waves and instabilities. In certain laboratory plasmas the dust is strongly coupled, as characterized by the condition {gamma}{sub d}=Q{sub d}{sup 2} exp(-d/{lambda}{sub D})/dT{sub d}{>=}1, where Q{sub d} is the dust charge, d is the intergrain spacing, T{sub d} is the dust thermal energy, and {lambda}{sub D} is the plasma screening length. When the dust is strongly coupled, the spatial correlation of the grains can affect the dispersion relation of these waves. We review our recent work [1] on the dispersion properties of dust acoustic waves in the strongly coupled (liquid) phase in a dusty plasma, including also the effects of dust-neutral collisions. We then discuss a preliminary analysis of the effect of strong dust coupling on an ion dust two-stream instability in a collisional dusty plasma. Applications to laboratory dusty plasmas are discussed.

  19. Acoustic wave propagation in heterogeneous structures including experimental validation

    NASA Technical Reports Server (NTRS)

    Baumeister, Kenneth J.; Dahl, Milo D.

    1989-01-01

    A finite element model was developed to solve for the acoustic pressure and energy fields in a heterogeneous suppressor. The derivations from the governing equations assumed that the material properties could vary with position resulting in a heterogeneous variable property two-dimensional wave equation. This eliminated the necessity of finding the boundary conditions between different materials. For a two-media region consisting of part air and part bulk absorber, a model was used to describe the bulk absorber properties in two directions. Complex metallic structures inside the air duct are simulated by simply changing element properties from air to the structural material in a pattern to describe the desired shapes. To verify the numerical theory, experiments were conducted without flow in a rectangular duct with a single folded cavity mounted above the duct and absorbing material mounted inside a cavity. Changes in a nearly plane wave sound field were measured on the wall opposite the absorbing cavity. Fairly good agreement was found in the standing wave pattern upstream of the absorber and in the decay of pressure level opposite the absorber, as a function of distance along the duct. The finite element model provides a convenient method for evaluating the acoustic properties of bulk absorbers.

  20. Propagation and generation of waves in solar atmosphere

    NASA Astrophysics Data System (ADS)

    Routh, Swati

    The fact that the temperature increases with height in the solar atmosphere has been known for many years. To maintain this temperature increase, sources of heating must be present in the atmosphere. One of the most important, and still unsolved, problems in solar physics is to identify the basic physical processes that are responsible for this heating, and explain solar activities caused by the heating. It is also observationally well-established that the solar atmosphere shows a broad range of oscillations that are different in magnetic and non-magnetic regions of the atmosphere. The oscillations are driven by propagating waves, which cause the atmosphere to oscillate at its natural (cutoff) frequency. Since different waves have different cutoff frequencies, it is important to have a method that would allow determining such cutoffs for the solar atmosphere. In this PhD dissertation, the concept of cutoff frequency is extended to inhomogeneous atmospheres, and a general method to determine the cutoff frequency is presented. The method leads to new forms of wave equations obtained for all wave variables, and allows deriving the cutoff frequency without formally solving the wave equations. The main result is that the derived cutoff frequency is a local quantity and that its value at a given atmospheric height determines the frequency that waves must have in order to be propagating at this height. The developed method is general enough, so that it can be used to establish theoretical bases for studying the propagation and generation of different waves in the solar atmosphere. Acoustic waves play an important role in the heating of magnetic-free regions of the solar atmosphere. To determine the propagation conditions for these waves in the non-isothermal solar atmosphere, the method is used to obtain the resulting acoustic cutoff frequency. This new cutoff frequency is a local quantity and it generalizes Lamb's acoustic cutoff frequency that was obtained for an

  1. Wave activated power generation system

    SciTech Connect

    Ono, Y.

    1983-08-09

    A wave activated power generation system of the float type is disclosed, comprising at least one piston-cylinder device having an anchored cylinder and a piston slidable in the cylinder and cooperating with the cylinder to form a pumping chamber above the piston and a low pressure chamber below the piston. The cylinder has an intake port and an exhaust port both formed at an upper port thereof to communicate with the pumping chamber and each provided with a check valve. A float is connected through a cable to the piston of the piston- cylinder device. A pair of fluid storages are connected to the intake port and the exhaust port of the pumping chamber, respectively. A waterwheel generator is driven by the fluid flowing from one of the fluid storages to another. A pressure regulating device is connected to the low pressure chamber so as to maintain the low pressure chamber at a pressure lower than the pressure in the pumping chamber, the difference in pressure ceaselessly applying a downward force on the piston to keep the cable in a tensed condition.

  2. Method and apparatus of spectro-acoustically enhanced ultrasonic detection for diagnostics

    DOEpatents

    Vo-Dinh, Tuan; Norton, Stephen J.

    2001-01-01

    An apparatus for detecting a discontinuity in a material includes a source of electromagnetic radiation has a wavelength and an intensity sufficient to induce an enhancement in contrast between a manifestation of an acoustic property in the material and of the acoustic property in the discontinuity, as compared to when the material is not irradiated by the electromagnetic radiation. An acoustic emitter directs acoustic waves to the discontinuity in the material. The acoustic waves have a sensitivity to the acoustic property. An acoustic receiver receives the acoustic waves generated by the acoustic emitter after the acoustic waves have interacted with the material and the discontinuity. The acoustic receiver also generates a signal representative of the acoustic waves received by the acoustic receiver. A processor, in communication with the acoustic receiver and responsive to the signal generated by the acoustic receiver, is programmed to generate informational output about the discontinuity based on the signal generated by the acoustic receiver.

  3. Sensing the characteristic acoustic impedance of a fluid utilizing acoustic pressure waves

    PubMed Central

    Antlinger, Hannes; Clara, Stefan; Beigelbeck, Roman; Cerimovic, Samir; Keplinger, Franz; Jakoby, Bernhard

    2012-01-01

    Ultrasonic sensors can be used to determine physical fluid parameters like viscosity, density, and speed of sound. In this contribution, we present the concept for an integrated sensor utilizing pressure waves to sense the characteristic acoustic impedance of a fluid. We note that the basic setup generally allows to determine the longitudinal viscosity and the speed of sound if it is operated in a resonant mode as will be discussed elsewhere. In this contribution, we particularly focus on a modified setup where interferences are suppressed by introducing a wedge reflector. This enables sensing of the liquid's characteristic acoustic impedance, which can serve as parameter in condition monitoring applications. We present a device model, experimental results and their evaluation. PMID:23565036

  4. A high-throughput standing surface acoustic wave (SSAW)-based cell sorter

    PubMed Central

    Li, Peng; Mao, Zhangming; Huang, Po-Hsun; Rufo, Joseph; Guo, Feng; Wang, Lin; McCoy, J. Philip; Levine, Stewart J.; Huang, Tony Jun

    2015-01-01

    Acoustic-based fluorescence activated cell sorters (FACS) have drawn increased attention in recent years due to their versatility, high biocompatibility, high controllability, and simple design. However, the sorting throughput for existing acoustic cell sorters is far from optimum for practical applications. Here we report a high-throughput cell sorting method based on standing surface acoustic waves (SSAWs). We utilized a pair of focused interdigital transducers (FIDTs) to generate SSAW with high resolution and high energy efficiency. As a result, the sorting throughput is improved significantly from conventional acoustic-based cell sorting methods. We demonstrated the successful sorting of 10 μm polystyrene particles with a minimum actuation time of 72 μs, which translates to a potential sorting rate of more than 13,800 events/s. Without using a cell-detection unit, we were able to demonstrate an actual sorting throughput of 3,300 events/s. Our sorting method can be conveniently integrated with upstream detection units, and it represents an important development towards a functional acoustic-based FACS system. PMID:26289231

  5. GPS-Acoustic Seafloor Geodesy using a Wave Glider

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Bouzit, Omar; Tribeche, Mouloud

    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.

  7. Modeling of a Surface Acoustic Wave Strain Sensor

    NASA Technical Reports Server (NTRS)

    Wilson, W. C.; Atkinson, Gary M.

    2010-01-01

    NASA Langley Research Center is investigating Surface Acoustic Wave (SAW) sensor technology for harsh environments aimed at aerospace applications. To aid in development of sensors a model of a SAW strain sensor has been developed. The new model extends the modified matrix method to include the response of Orthogonal Frequency Coded (OFC) reflectors and the response of SAW devices to strain. These results show that the model accurately captures the strain response of a SAW sensor on a Langasite substrate. The results of the model of a SAW Strain Sensor on Langasite are presented

  8. Dual output acoustic wave sensor for molecular identification

    DOEpatents

    Frye, Gregory C.; Martin, Stephen J.

    1991-01-01

    A method of identification and quantification of absorbed chemical species by measuring changes in both the velocity and the attenuation of an acoustic wave traveling through a thin film into which the chemical species is sorbed. The dual output response provides two independent sensor responses from a single sensing device thereby providing twice as much information as a single output sensor. This dual output technique and analysis allows a single sensor to provide both the concentration and the identity of a chemical species or permits the number of sensors required for mixtures to be reduced by a factor of two.

  9. Hydrogen Adsorption Studies Using Surface Acoustic Waves on Nanoparticles

    SciTech Connect

    A.B. Phillips; G. Myneni; B.S. Shivaram

    2005-06-13

    Vanadium nanoparticles, on the order of 20 nm, were deposited on a quartz crystal surface acoustic wave resonator (SAW) using a Nd:YAG pulsed laser deposition system. Due to the high Q and resonant frequency of the SAW, mass changes on the order of 0.1 nanogram can be quantitatively measured. Roughly 60 nanogram of V was deposited on the SAW for these experiments. The SAW was then moved into a hydrogen high pressure cell.At room temperature and 1 atmosphere of hydrogen pressure, 1 wt% H, or H/V {approx} 0.5 (atomic ratio) absorption was measured.

  10. Location Dependence of Mass Sensitivity for Acoustic Wave Devices

    PubMed Central

    Zhang, Kewei; Chai, Yuesheng; Cheng, Z.-Y.

    2015-01-01

    It is introduced that the mass sensitivity (Sm) of an acoustic wave (AW) device with a concentrated mass can be simply determined using its mode shape function: the Sm is proportional to the square of its mode shape. By using the Sm of an AW device with a uniform mass, which is known for almost all AW devices, the Sm of an AW device with a concentrated mass at different locations can be determined. The method is confirmed by numerical simulation for one type of AW device and the results from two other types of AW devices. PMID:26404313

  11. Potential of surface acoustic wave biosensors for early sepsis diagnosis.

    PubMed

    Csete, Marie; Hunt, William D

    2013-08-01

    Early diagnosis of sepsis is a difficult problem for intensivists and new biomarkers for early diagnosis have been difficult to come by. Here we discuss the potential of adapting a technology from the electronics industry, surface acoustic wave (SAW) sensors, for diagnosis of multiple markers of sepsis in real time, using non-invasive assays of exhaled breath condensate. The principles and advantages of the SAW technology are reviewed as well as a proposed plan for adapting this flexible technology to early sepsis detection. PMID:23471596

  12. An oxygen pressure sensor using surface acoustic wave devices

    NASA Technical Reports Server (NTRS)

    Leighty, Bradley D.; Upchurch, Billy T.; Oglesby, Donald M.

    1993-01-01

    Surface acoustic wave (SAW) piezoelectric devices are finding widespread applications in many arenas, particularly in the area of chemical sensing. We have developed an oxygen pressure sensor based on coating a SAW device with an oxygen binding agent which can be tailored to provide variable sensitivity. The coating is prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer which is then sprayed onto the surface of the SAW device. Experimental data shows the feasibility of tailoring sensors to measure the partial pressure of oxygen from 2.6 to 67 KPa (20 to 500 torr). Potential applications of this technology are discussed.

  13. Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

    NASA Astrophysics Data System (ADS)

    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

  14. Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

    SciTech Connect

    Lipkens, Bart; Ilinskii, Yurii A. Zabolotskaya, Evgenia A.

    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

  15. Mechanical back-action of a spin-wave resonance in a magnetoelastic thin film on a surface acoustic wave

    NASA Astrophysics Data System (ADS)

    Gowtham, P. G.; Labanowski, D.; Salahuddin, S.

    2016-07-01

    Surface acoustic waves (SAWs) traveling on the surface of a piezoelectric crystal can, through the magnetoelastic interaction, excite traveling spin-wave resonance in a magnetic film deposited on the substrate. This spin-wave resonance in the magnetic film creates a time-ynamic surface stress of magnetoelastic origin that acts back on the surface of the piezoelectric and modifies the SAW propagation. Unlike previous analyses that treat the excitation as a magnon-phonon polariton, here the magnetoelastic film is treated as a perturbation modifying boundary conditions on the SAW. We use acoustical perturbation theory to find closed-form expressions for the back-action surface stress and strain fields and the resultant SAW velocity shifts and attenuation. We demonstrate that the shear stres fields associated with this spin-wave back-action also generate effective surface currents on the piezoelectric both in phase and out of phase with the driving SAW potential. Characterization of these surface currents and their applications in determination of the magnetoelastic coupling are discussed. The perturbative calculation is carried out explicitly to first order (a regime corresponding to many experimental situations of current interest) and we provide a sketch of the implications of the theory at higher order.

  16. Solar wind implication on dust ion acoustic rogue waves

    NASA Astrophysics Data System (ADS)

    Abdelghany, A. M.; Abd El-Razek, H. N.; Moslem, W. M.; El-Labany, S. K.

    2016-06-01

    The relevance of the solar wind with the magnetosphere of Jupiter that contains positively charged dust grains is investigated. The perturbation/excitation caused by streaming ions and electron beams from the solar wind could form different nonlinear structures such as rogue waves, depending on the dominant role of the plasma parameters. Using the reductive perturbation method, the basic set of fluid equations is reduced to modified Korteweg-de Vries (KdV) and further modified (KdV) equation. Assuming that the frequency of the carrier wave is much smaller than the ion plasma frequency, these equations are transformed into nonlinear Schrödinger equations with appropriate coefficients. Rational solution of the nonlinear Schrödinger equation shows that rogue wave envelopes are supported by the present plasma model. It is found that the existence region of rogue waves depends on the dust-acoustic speed and the streaming temperatures for both the ions and electrons. The dependence of the maximum rogue wave envelope amplitude on the system parameters has been investigated.

  17. Three dimensional full-wave nonlinear acoustic simulations: Applications to ultrasound imaging

    SciTech Connect

    Pinton, Gianmarco

    2015-10-28

    Characterization of acoustic waves that propagate nonlinearly in an inhomogeneous medium has significant applications to diagnostic and therapeutic ultrasound. The generation of an ultrasound image of human tissue is based on the complex physics of acoustic wave propagation: diffraction, reflection, scattering, frequency dependent attenuation, and nonlinearity. The nonlinearity of wave propagation is used to the advantage of diagnostic scanners that use the harmonic components of the ultrasonic signal to improve the resolution and penetration of clinical scanners. One approach to simulating ultrasound images is to make approximations that can reduce the physics to systems that have a low computational cost. Here a maximalist approach is taken and the full three dimensional wave physics is simulated with finite differences. This paper demonstrates how finite difference simulations for the nonlinear acoustic wave equation can be used to generate physically realistic two and three dimensional ultrasound images anywhere in the body. A specific intercostal liver imaging scenario for two cases: with the ribs in place, and with the ribs removed. This configuration provides an imaging scenario that cannot be performed in vivo but that can test the influence of the ribs on image quality. Several imaging properties are studied, in particular the beamplots, the spatial coherence at the transducer surface, the distributed phase aberration, and the lesion detectability for imaging at the fundamental and harmonic frequencies. The results indicate, counterintuitively, that at the fundamental frequency the beamplot improves due to the apodization effect of the ribs but at the same time there is more degradation from reverberation clutter. At the harmonic frequency there is significantly less improvement in the beamplot and also significantly less degradation from reverberation. It is shown that even though simulating the full propagation physics is computationally challenging it

  18. Three dimensional full-wave nonlinear acoustic simulations: Applications to ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Pinton, Gianmarco

    2015-10-01

    Characterization of acoustic waves that propagate nonlinearly in an inhomogeneous medium has significant applications to diagnostic and therapeutic ultrasound. The generation of an ultrasound image of human tissue is based on the complex physics of acoustic wave propagation: diffraction, reflection, scattering, frequency dependent attenuation, and nonlinearity. The nonlinearity of wave propagation is used to the advantage of diagnostic scanners that use the harmonic components of the ultrasonic signal to improve the resolution and penetration of clinical scanners. One approach to simulating ultrasound images is to make approximations that can reduce the physics to systems that have a low computational cost. Here a maximalist approach is taken and the full three dimensional wave physics is simulated with finite differences. This paper demonstrates how finite difference simulations for the nonlinear acoustic wave equation can be used to generate physically realistic two and three dimensional ultrasound images anywhere in the body. A specific intercostal liver imaging scenario for two cases: with the ribs in place, and with the ribs removed. This configuration provides an imaging scenario that cannot be performed in vivo but that can test the influence of the ribs on image quality. Several imaging properties are studied, in particular the beamplots, the spatial coherence at the transducer surface, the distributed phase aberration, and the lesion detectability for imaging at the fundamental and harmonic frequencies. The results indicate, counterintuitively, that at the fundamental frequency the beamplot improves due to the apodization effect of the ribs but at the same time there is more degradation from reverberation clutter. At the harmonic frequency there is significantly less improvement in the beamplot and also significantly less degradation from reverberation. It is shown that even though simulating the full propagation physics is computationally challenging it

  19. Virtual membrane for filtration of particles using surface acoustic waves (SAW).

    PubMed

    Fakhfouri, Armaghan; Devendran, Citsabehsan; Collins, David J; Ai, Ye; Neild, Adrian

    2016-09-21

    Surface acoustic wave (SAW) based particle manipulation is contactless, versatile, non-invasive and biocompatible making it useful for biological studies and diagnostic technologies. In this work, we present a sensitive particle sorting system, termed the virtual membrane, in which a periodic acoustic field with a wavelength on the order of particle dimensions permits size-selective filtration. Polystyrene particles that are larger than approximately 0.3 times the acoustic half-wavelength experience a force repelling them from the acoustic field. If the particle size is such that, at a given acoustic power and flow velocity, this repulsive force is dominant over the drag force, these particles will be prohibited from progressing further downstream (i.e. filtered), while smaller particles will be able to pass through the force field along the pressure nodes (akin to a filter's pores). Using this mechanism, we demonstrate high size selectivity using a standing SAW generated by opposing sets of focused interdigital transducers (FIDTs). The use of FIDTs permits the generation of a highly localized standing wave field, here used for filtration in μl min(-1) order flow rates at 10s of mW of applied power. Specifically, we demonstrate the filtration of 8 μm particles from 5 μm particles and 10.36 μm particles from 7.0 μm and 5.0 μm particles, using high frequency SAW at 258 MHz, 192.5 MHz, and 129.5 MHz, respectively. PMID:27458086

  20. Acoustic Optimization of Automotive Exhaust Heat Thermoelectric Generator

    NASA Astrophysics Data System (ADS)

    Su, C. Q.; Ye, B. Q.; Guo, X.; Hui, P.

    2012-06-01

    The potential for thermoelectric exhaust heat recovery in vehicles has been increasing with recent advances in the efficiency of thermoelectric generators (TEGs). This study analyzes the acoustic attenuation performance of exhaust-based TEGs. The acoustic characteristics of two different thermal designs of exhaust gas heat exchanger in TEGs are discussed in terms of transmission loss and acoustic insertion loss. GT-Power simulations and bench tests on a dynamometer with a high-performance production engine are carried out. Results indicate that the acoustic attenuation of TEGs could be determined and optimized. In addition, the feasibility of integration of exhaust-based TEGs and engine mufflers into the exhaust line is tested, which can help to reduce space and improve vehicle integration.

  1. 2D fluid simulations of acoustic waves in pulsed ICP discharges: Comparison with experiments

    NASA Astrophysics Data System (ADS)

    Despiau-Pujo, Emilie; Cunge, Gilles; Sadeghi, Nader; Braithwaite, N. St. J.

    2012-10-01

    Neutral depletion, which is mostly caused by gas heating under typical material processing conditions, is an important phenomenon in high-density plasmas. In low pressure pulsed discharges, experiments show that additional depletion due to electron pressure (Pe) may have a non-negligible influence on radical transport [1]. To evaluate this effect, comparisons between 2D fluid simulations and measurements of gas convection in Ar/Cl2 pulsed ICP plasmas are reported. In the afterglow, Pe drops rapidly by electron cooling which generates a neutral pressure gradient between the plasma bulk and the reactor walls. This in turn forces the cold surrounding gas to move rapidly towards the center, thus launching an acoustic wave in the reactor. Time-resolved measurements of atoms drift velocity and gas temperature by LIF and LAS in the early afterglow are consistent with gas drifting at acoustic wave velocity followed by rapid gas cooling. Similar results are predicted by the model. The ion flux at the reactor walls is also shown to oscillate in phase with the acoustic wave due to ion-neutral friction forces. Finally, during plasma ignition, experiments show opposite phenomena when Pe rises.[4pt] [1] Cunge et al, APL 96, 131501 (2010)

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

    SciTech Connect

    Lopes, Ilídio; Silk, Joseph E-mail: ilopes@uevora.pt

    2014-10-10

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

  3. A superconducting qubit coupled to propagating acoustic waves

    NASA Astrophysics Data System (ADS)

    Gustafsson, Martin V.; Aref, Thomas; Frisk Kockum, Anton; Ekström, Maria K.; Johansson, Göran; Delsing, Per

    2015-03-01

    Mechanical devices in the quantum regime have so far consisted mainly of suspended resonators, where standing modes can be populated with quanta of vibrational energy. We present a fundamentally different system, where the mechanical excitation is not restricted to a specific mode and location. Instead, we demonstrate strong non-classical coupling between propagating phonons and a superconducting qubit. The qubit is fabricated on a piezoelectric substrate, and is designed to interact with Surface Acoustic Waves (SAWs) in the gigahertz frequency range. A separate on-chip transducer allows us to launch SAWs toward the qubit from a distance and pick up SAW phonons that the qubit reflects and emits. In a series of experiments where the qubit is addressed both electrically and acoustically, we show that the qubit couples much more strongly to SAWs than to any electrical modes. The low speed of sound sets phonons apart from photons as a medium for transporting quantum information, and should enable real-time manipulation of propagating quanta. The short acoustic wavelength and strong piezoelectric coupling should also allows regimes of interaction to be explored which cannot be reached in photonic systems.

  4. Helioseismology and Asteroseismology: Looking for Gravitational Waves in Acoustic Oscillations

    NASA Astrophysics Data System (ADS)

    Lopes, Ilídio; Silk, Joseph

    2014-10-01

    Current helioseismology observations allow the determination of the frequencies and surface velocity amplitudes of solar acoustic modes with exceptionally high precision. In some cases, the frequency accuracy is better than one part in a million. We show that there is a distinct possibility that quadrupole acoustic modes of low order could be excited by gravitational waves (GWs), if the GWs have a strain amplitude in the range 10-20 h -20 with h -20 ~ 1 or h -20 ~ 103, as predicted by several types of GW sources, such as galactic ultracompact binaries or extreme mass ratio inspirals and coalescence of black holes. If the damping rate at low order is 10-3η N μHz, with η N ~ 10-3-1, as inferred from the theory of stellar pulsations, then GW radiation will lead to a maximum rms surface velocity amplitude of quadrupole modes of the order of h_{-20}\\eta _N^{-1}\\sim 10-9-10-3 cm s-1, on the verge of what is currently detectable via helioseismology. The frequency and sensitivity range probed by helioseismological acoustic modes overlap with, and complement, the capabilities of eLISA for the brightest resolved ultracompact galactic binaries.

  5. On-demand droplet splitting using surface acoustic waves.

    PubMed

    Jung, Jin Ho; Destgeer, Ghulam; Ha, Byunghang; Park, Jinsoo; Sung, Hyung Jin

    2016-08-16

    We demonstrated the operation of an acoustomicrofluidic device composed of a polydimethylsiloxane (PDMS) microchannel and a slanted-finger interdigitated transducer (SF-IDT), for the on-demand splitting of droplets in an active, accurate, rapid, and size-controllable manner. A narrow beam of surface acoustic waves (SAWs) that emanated from the SF-IDT exerted an acoustic radiation force (ARF) on the droplet's water-oil interface due to the acoustic contrast between the two fluids. The ARF split the mother droplet into two or more daughter droplets of various volumes in a split ratio that was readily controlled by varying the applied voltage or the flow rate. Theoretical estimates of the ARF acting on the droplet interface were used to investigate the mechanism underlying the droplet splitting properties and size control. The versatility of the acoustomicrofluidic device operation was demonstrated by selectively pushing/placing a suspended polystyrene particle into a specific/preferred split daughter droplet using the direct ARF acting on the particle. PMID:27435869

  6. Excitation and Damping of Acoustic Waves in Three-Dimensional Accretion Disks

    NASA Astrophysics Data System (ADS)

    Mosqueira, I.; Houben, H.

    2002-09-01

    The damping of acoustic waves plays a key role in determining the criterion for gap opening (see Estrada and Mosqueira, this conference). Because of the potential significance of gap-opening in regulating the rate of accretion and of radial migration, it is important to investigate all sources of wave damping in an accretion disk. Here we mainly discuss damping mechanisms arising from 3-D effects in disks with aspect ratio H/r ~ 0.1. A 2-D treatment is valid when the response of the disk is locally isothermal with adiabatic index γ = 1 and the vertical forcing is ignored. In that case, tidal forcing will generate a 2-D wave which is likely to damp due to wave steepening in a lengthscale of order ~ rL (with weak dependence on the mass of the pertuber), where rL is the radial location of the Lindblad resonance where the acoustic wave is launched (Goodman and Rafikov 2001; Rafikov 2002). On the other hand, vertically thermally stratified disks, as may be the case for active disks with high-optical depth, generate 3-D waves which damp due to non-linear dissipation in a lengthscale of order ~ rL/m, where m is the azimuthal wavenumber (Lubow and Ogilvie 1998). In this case, most of the angular momentum flux is carried by the f-mode; however, tidal forcing also excites other modes. Finally, in a vertically isothermal (but not radially) disk with γ = 5/3 horizontal tidal forcing excites buoyancy g waves that receive ~ 20 per cent of the energy flux for a m = 0 mode (Bate et al. 2002). These g-waves have non-zero vertical group velocity, and are excited primarily away from the midplane, where non-linear dissipation is more readily attained. The radial damping length for these waves is likely to be ~ H and only weakly dependent on the mass of the perturber. We generalize the problem to include the effects of vertical tidal forcing in a vertically isothermal atmosphere with γ > 1, and calculate the vertical flux of angular momentum of acoustic waves with m < r/H. The

  7. Preliminary measurements of thermal effects in the dust acoustic wave

    NASA Astrophysics Data System (ADS)

    Williams, Jeremiah

    2009-11-01

    A complex (dusty) plasma (CDP) is a four-component system composed of ions, electrons, neutral particles and charged microparticles. The presence of the microparticles gives rise to new plasma phenomena, including collective modes such as the dust acoustic wave. Recent measurements of the dispersion relationship of this wave mode [E. Thomas, Jr., et. al., Phys. Plasmas 14, 123701 (2007), J.D. Williams, et. al., Phys. Plasmas 15, 043704 (2008)] have shown that, over a range of neutral gas pressures, it is necessary to include thermal effects to accurately fit the measured dispersion relations. In this work, initial measurements of the dispersion relation in a new dusty plasma experiment, the Wittenberg University DUsty Plasma Experiment (WUDUPE), will be presented. In particular, the dependence of the kinetic dust temperature on the neutral gas pressure will be presented.

  8. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  9. Weakly dissipative dust-ion acoustic wave modulation

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  10. Arbitrary amplitude quantum dust ion-acoustic solitary waves

    SciTech Connect

    Tribeche, Mouloud; Ghebache, Siham; Aoutou, Kamel; Zerguini, Taha Houssine

    2008-03-15

    The one-dimensional quantum hydrodynamic model for a three-species quantum plasma is used to study the quantum counterpart of the well known dust ion-acoustic (DIA) wave. Two cases of physical interest are investigated, namely positive and negative dust charge. It is shown that only rarefactive solitary potentials associated with nonlinear quantum DIA (QDIA) waves involving electron density deeps can exist. The QDIA soliton experiences a spreading and the quantum effects tend to make it wider. Under certain conditions, the soliton enlarges and its pulse shape evolves into a broad central flat-bottomed (or table-bottomed) soliton as a limiting-amplitude member of the QDIA soliton family. Linear stability analysis as well as quasineutral solutions are succinctly outlined. The investigation could be of relevance to astrophysical quantum dusty plasmas.

  11. Nonlinear positron-acoustic waves in fully relativistic degenerate plasmas

    NASA Astrophysics Data System (ADS)

    Hossen, M. A.; Mamun, A. A.

    2016-03-01

    The nonlinear positron-acoustic (PA) waves propagating in a fully relativistic electron-positron-ion (EPI) plasma (containing degenerate electrons and positrons, and immobile heavy ions) have been theoretically investigated. A fully relativistic hydrodynamic model, which is consistent with the relativistic principle has been used, and the reductive perturbation method is employed to derive the dynamical Korteweg-de Vries equation. The dynamics of electrons as well as positrons, and the presence of immobile heavy ions are taken into account. It is found that the effects of relativistic degeneracy of electrons and positrons, static heavy ions, plasma particles velocity, enthalpy, etc have significantly modified the basic properties of the PA solitary waves propagating in the fully relativistic EPI plasmas. The application of the results of our present work in astrophysical compact objects such as white dwarfs and neutron stars, etc are briefly discussed.

  12. Anomalous refraction of guided waves via embedded acoustic metasurfaces

    NASA Astrophysics Data System (ADS)

    Zhu, Hongfei; Semperlotti, Fabio

    2016-04-01

    We illustrate the design of acoustic metasurfaces based on geometric tapers and embedded in thin-plate structures. The metasurface is an engineered discontinuity that enables anomalous refraction of guided wave modes according to the Generalized Snell's Law. Locally-resonant geometric torus-like tapers are designed in order to achieve metasurfaces having discrete phase-shift profiles that enable a high level of control of refraction of the wavefronts. Results of numerical simulations show that anomalous refraction can be achieved on transmitted anti-symmetric modes (A0) either when using a symmetric (S0) or anti-symmetric (A0) incident wave, where the former case clearly involves mode conversion mechanisms.

  13. Gravitational wave detection with high frequency phonon trapping acoustic cavities

    NASA Astrophysics Data System (ADS)

    Goryachev, Maxim; Tobar, Michael E.

    2014-11-01

    There are a number of theoretical predictions for astrophysical and cosmological objects, which emit high frequency (1 06-1 09 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 ultrahigh 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 1 0-22 per √{Hz } per mode is possible, which in principle can cover the frequency range with multiple (>100 ) modes with quality factors varying between 1 06 and 1 010 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.

  14. System for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher

    2012-07-31

    In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

  15. System for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher

    2012-09-04

    In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

  16. Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt; Schmitt, Denis P.; Skelt, Christopher

    2010-11-23

    In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

  17. Prediction of the Acoustic Field Associated with Instability Wave Source Model for a Compressible Jet

    NASA Technical Reports Server (NTRS)

    Golubev, Vladimir; Mankbadi, Reda R.; Dahl, Milo D.; Kiraly, L. James (Technical Monitor)

    2002-01-01

    This paper provides preliminary results of the study of the acoustic radiation from the source model representing spatially-growing instability waves in a round jet at high speeds. The source model is briefly discussed first followed by the analysis of the produced acoustic directivity pattern. Two integral surface techniques are discussed and compared for prediction of the jet acoustic radiation field.

  18. Comparative Study of Bio-implantable Acoustic Generator Architectures

    NASA Astrophysics Data System (ADS)

    Christensen, D.; Roundy, S.

    2013-12-01

    This paper is a comparative study of the design spaces of two bio-implantable acoustically excited generator architectures: the thickness-stretch-mode circular piezoelectric plate and the bending-mode unimorph piezoelectric diaphragm. The generators are part of an acoustic power transfer system for implanted sensors and medical devices such as glucose monitors, metabolic monitors, drug delivery systems, etc. Our studies indicate that at small sizes the diaphragm architecture outperforms the plate architecture. This paper will present the results of simulation studies and initial experiments that explore the characteristics of the two architectures and compare their performance.

  19. Precise rainbow trapping for low-frequency acoustic waves with micro Mie resonance-based structures

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Yuan, Baoguo; Cheng, Ying; Liu, Xiaojun

    2016-02-01

    We have realized the acoustic rainbow trapping in the low frequency region (200-500 Hz) through micro Mie resonance-based structures. The structure has eight channels with a high refractive index obtained by coiling space, that can excite strong interactions with incident waves and support various orders of multipoles due to the Mie resonances of the microstructure. By utilizing the structure, the precise spatial modulation of the acoustic wave is demonstrated both theoretically and experimentally. The effect of trapping broadband acoustic waves and spatially separating different frequency components are ascribed to the monopolar Mie resonances of the structures. The trapping frequency is derived and the trapping positions can be tuned arbitrarily. With enhanced wave-structure interactions and tailored frequency responses, such micro structures show precise spectral-spatial control of acoustic waves and open a diverse venue for high performance acoustic wave detection, sensing, filtering, and a nondestructive test.

  20. Acoustic Wave Chemical Microsensors in GaAs

    SciTech Connect

    Albert G. Baca; Edwin J. Heller; Gregory C. Frye-Mason; John L. Reno; Richard Kottenstette; Stephen A. Casalnuovo; Susan L. Hietala; Vincent M. Hietala

    1998-09-20

    High sensitivity acoustic wave chemical microsensors are being developed on GaAs substrates. These devices take advantage of the piezoelectric properties of GaAs as well as its mature microelectronics fabrication technology and nascent micromachining technology. The design, fabrication, and response of GaAs SAW chemical microsensors are reported. Functional integrated GaAs SAW oscillators, suitable for chemical sensing, have been produced. The integrated oscillator requires 20 mA at 3 VK, operates at frequencies up to 500 MHz, and occupies approximately 2 mmz. Discrete GaAs sensor components, including IC amplifiers, SAW delay lines, and IC phase comparators have been fabricated and tested. A temperature compensation scheme has been developed that overcomes the large temperature dependence of GaAs acoustic wave devices. Packaging issues related to bonding miniature flow channels directly to the GaAs substrates have been resolved. Micromachining techniques for fabricating FPW and TSM microsensors on thin GaAs membranes are presented and GaAs FPW delay line performance is described. These devices have potentially higher sensitivity than existing GaAs and quartz SAW sensors.

  1. A micromachined surface acoustic wave sensor for detecting inert gases

    SciTech Connect

    Ahuja, S.; Hersam, M.; Ross, C.; Chien, H.T.; Raptis, A.C.

    1996-12-31

    Surface acoustic wave (SAW) sensors must be specifically designed for each application because many variables directly affect the acoustic wave velocity. In the present work, the authors have designed, fabricated, and tested an SAW sensor for detection of metastable states of He. The sensor consists of two sets of micromachined interdigitated transducers (IDTs) and delay lines fabricated by photolithography on a single Y-cut LiNbO{sub 3} substrate oriented for Z-propagation of the SAWs. One set is used as a reference and the other set employs a delay line coated with a titanium-based thin film sensitive to electrical conductivity changes when exposed to metastable states of He. The reference sensor is used to obtain a true frequency translation in relation to a voltage controlled oscillator. An operating frequency of 109 MHz has been used, and the IDT finger width is 8 {micro}m. Variation in electrical conductivity of the thin film at the delay line due to exposure to He is detected as a frequency shift in the assembly, which is then used as a measure of the amount of metastable He exposed to the sensing film on the SAW delay line. A variation in the He pressure versus frequency shifts indicates the extent of the metastable He interaction.

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

    PubMed

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

    2016-02-01

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

  3. Guided wave acoustic monitoring of corrosion in recovery boiler tubing

    SciTech Connect

    Quarry, M J; Chinn, D J

    2004-02-19

    Corrosion of tubing used in black-liquor recovery boilers is a major concern in all pulp and paper mills. Extensive corrosion in recovery boiler tubes can result in a significant safety and environmental hazard. Considerable plant resources are expended to inspect recovery boiler tubing. Currently, visual and ultrasonic inspections are primarily used during the annual maintenance shutdown to monitor corrosion rates and cracking of tubing. This Department of Energy, Office of Industrial Technologies project is developing guided acoustic waves for use on recovery boiler tubing. The feature of this acoustic technique is its cost-effectiveness in inspecting long lengths of tubes from a single inspection point. A piezoelectric or electromagnetic transducer induces guided waves into the tubes. The transducer detects fireside defects from the coldside or fireside of the tube. Cracking and thinning on recovery boiler tubes have been detected with this technique in both laboratory and field applications. This technique appears very promising for recovery boiler tube application, potentially expediting annual inspection of tube integrity.

  4. 2-D modeling of laterally acoustically coupled thin film bulk acoustic wave resonator filters.

    PubMed

    Pensala, Tuomas; Meltaus, Johanna; Kokkonen, Kimmo; Ylilammi, Markku

    2010-11-01

    A 2-D model is developed for calculating lateral acoustical coupling between adjacent thin film BAW resonators forming an electrical N-port. The model is based on solution and superposition of lateral eigenmodes and eigenfrequencies in a structure consisting of adjacent regions with known plate wave dispersion properties. Mechanical and electrical response of the device are calculated as a superposition of eigenmodes according to voltage drive at one electrical port at a time while extracting current induced in the other ports, leading to a full Y-parameter description of the device. Exemplary cases are simulated to show the usefulness of the model in the study of the basic design rules of laterally coupled thin film BAW resonator filters. Model predictions are compared to an experimental 1.9-GHz band-pass filter based on aluminum nitride thin film technology and lateral acoustical coupling. Good agreement is obtained in prediction of passband behavior. The eigenmode-based model forms a useful tool for fast simulation of laterally coupled acoustic devices. It allows one to gain insight into basic device physics in a very intuitive fashion compared with more detailed but heavier finite element method. Shortcomings of this model and possible improvements are discussed. PMID:21041141

  5. Efficient laser generation of Lamb waves.

    PubMed

    Huke, Philipp; Schröder, Martin; Hellmers, Sandra; Kalms, Michael; Bergmann, Ralf B

    2014-10-15

    We report about the efficient generation of Lamb waves for nondestructive testing (NDT) of carbon fiber reinforced plastics (CFRP) with spatially formed laser beams. Therefore we describe the successful introduction of a liquid crystal on silicon (LCoS)-based spatial light modulator (SLM) to create predetermined spatial laser light distributions for a flexible Lamb wave excitation. We investigate the influence of the formed beam profiles of the generation laser to the resulting Lamb wave. The further objective of the study is the close adaptation of the laser-generated guided waves to a specific testing situation and an optimized defect evaluation. PMID:25361087

  6. Acoustic measurements of a liquefied cohesive sediment bed under waves

    NASA Astrophysics Data System (ADS)

    Mosquera, R.; Groposo, V.; Pedocchi, F.

    2014-04-01

    In this article the response of a cohesive sediment deposit under the action of water waves is studied with the help of laboratory experiments and an analytical model. Under the same regular wave condition three different bed responses were observed depending on the degree of consolidation of the deposit: no bed motion, bed motion of the upper layer after the action of the first waves, and massive bed motion after several waves. The kinematic of the upper 3 cm of the deposit were measured with an ultrasound acoustic profiler, while the pore-water pressure inside the bed was simultaneously measured using several pore pressure sensors. A poro-elastic model was developed to interpret the experimental observations. The model showed that the amplitude of the shear stress increased down into the bed. Then it is possible that the lower layers of the deposit experience plastic deformations, while the upper layers present just elastic deformations. Since plastic deformations in the lower layers are necessary for pore pressure build-up, the analytical model was used to interpret the experimental results and to state that liquefaction of a self consolidated cohesive sediment bed would only occur if the bed yield stress falls within the range defined by the amplitude of the shear stress inside the bed.

  7. Analyses of Acoustic Streaming Generated by Four Ultrasonic Vibrators in a Vessel

    NASA Astrophysics Data System (ADS)

    Nakagawa, Masafumi

    2004-05-01

    When ultrasonic waves are applied, the heat transfer at a heated surface in water increases markedly. The origin of this increase in heat transfer is thought to be due to the agitation effect from the microjets of cavitation and from acoustic streaming. The method in which four vibrators are used has the ability of further enhancing heat transfer. This paper presents the method using four vibrators to eject an acoustic stream jet at a selected position in the vessel. Analyses of this method are performed to establish it theoretically and to compare with an experiment previously conducted. The analyses shown in this research indicate that the aspects of acoustic streaming generated by the four vibrators in the vessel can be correctly predicted and provide a foundation for the development of using this method for the enhancement of heat transfer.

  8. Astrocytes generate Na+-mediated metabolic waves

    NASA Astrophysics Data System (ADS)

    Bernardinelli, Yann; Magistretti, Pierre J.; Chatton, Jean-Yves

    2004-10-01

    Glutamate-evoked Na+ increase in astrocytes has been identified as a signal coupling synaptic activity to glucose consumption. Astrocytes participate in multicellular signaling by transmitting intercellular Ca2+ waves. Here we show that intercellular Na+ waves are also evoked by activation of single cultured cortical mouse astrocytes in parallel with Ca2+ waves; however, there are spatial and temporal differences. Indeed, maneuvers that inhibit Ca2+ waves also inhibit Na+ waves; however, inhibition of the Na+/glutamate cotransporters or enzymatic degradation of extracellular glutamate selectively inhibit the Na+ wave. Thus, glutamate released by a Ca2+ wave-dependent mechanism is taken up by the Na+/glutamate cotransporters, resulting in a regenerative propagation of cytosolic Na+ increases. The Na+ wave gives rise to a spatially correlated increase in glucose uptake, which is prevented by glutamate transporter inhibition. Therefore, astrocytes appear to function as a network for concerted neurometabolic coupling through the generation of intercellular Na+ and metabolic waves.

  9. Generation of rogue waves in a wave tank

    NASA Astrophysics Data System (ADS)

    Lechuga, A.

    2012-04-01

    Rogue waves have been reported as causing damages and ship accidents all over the oceans of the world. For this reason in the past decades theoretical studies have been carried out with the double aim of improving the knowledge of their main characteristics and of attempting to predict its sudden appearance. As an effort on this line we are trying to generate them in a water tank. The description of the procedure to do that is the objective of this presentation. After Akhmediev et al. (2011) we use a symmetric spectrum as input on the wave maker to produce waves with a rate(Maximun wave height/ significant wave height) of 2.33 and a kurtosis of 4.77, clearly between the limits of rogue waves. As it was pointed out by Janssen (2003), Onorato et al. (2006) and Kharif, Pelinovsky and Slunyaev (2009) modulation instability is enhanced when waves depart from Gaussian statistics (i.e. big kurtosis) and therefore both numbers enforce the criterion that we are generating genuine rogue waves. The same is confirmed by Shemer (2010) and Dudley et al.(2009) from a different perspective. If besides being symmetrical the spectrum is triangular, following Akhmediev(2011),the generated waves are even more conspicuously rogue waves.

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

    PubMed Central

    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

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  13. Acoustic-wave sensor for ambient monitoring of a photoresist-stripping agent

    DOEpatents

    Pfeifer, Kent B.; Hoyt, Andrea E.; Frye, Gregory C.

    1998-01-01

    The acoustic-wave sensor. The acoustic-wave sensor is designed for ambient or vapor-phase monitoring of a photoresist-stripping agent such as N-methylpyrrolidinone (NMP), ethoxyethylpropionate (EEP) or the like. The acoustic-wave sensor comprises an acoustic-wave device such as a surface-acoustic-wave (SAW) device, a flexural-plate-wave (FPW) device, an acoustic-plate-mode (APM) device, or a thickness-shear-mode (TSM) device (also termed a quartz crystal microbalance or QCM) having a sensing region on a surface thereof. The sensing region includes a sensing film for sorbing a quantity of the photoresist-stripping agent, thereby altering or shifting a frequency of oscillation of an acoustic wave propagating through the sensing region for indicating an ambient concentration of the agent. According to preferred embodiments of the invention, the acoustic-wave device is a SAW device; and the sensing film comprises poly(vinylacetate), poly(N-vinylpyrrolidinone), or poly(vinylphenol).

  14. Acoustic-wave sensor for ambient monitoring of a photoresist-stripping agent

    DOEpatents

    Pfeifer, K.B.; Hoyt, A.E.; Frye, G.C.

    1998-08-18

    The acoustic-wave sensor is disclosed. The acoustic-wave sensor is designed for ambient or vapor-phase monitoring of a photoresist-stripping agent such as N-methylpyrrolidinone (NMP), ethoxyethylpropionate (EEP) or the like. The acoustic-wave sensor comprises an acoustic-wave device such as a surface-acoustic-wave (SAW) device, a flexural-plate-wave (FPW) device, an acoustic-plate-mode (APM) device, or a thickness-shear-mode (TSM) device (also termed a quartz crystal microbalance or QCM) having a sensing region on a surface thereof. The sensing region includes a sensing film for sorbing a quantity of the photoresist-stripping agent, thereby altering or shifting a frequency of oscillation of an acoustic wave propagating through the sensing region for indicating an ambient concentration of the agent. According to preferred embodiments of the invention, the acoustic-wave device is a SAW device; and the sensing film comprises poly(vinylacetate), poly(N-vinylpyrrolidinone), or poly(vinylphenol). 3 figs.

  15. Detection of in-plane displacements of acoustic wave fields using extrinsic Fizeau fiber interferometric sensors

    NASA Technical Reports Server (NTRS)

    Dhawan, R.; Gunther, M. F.; Claus, R. O.

    1991-01-01

    Quantitative measurements of the in-plane particle displacement components of ultrasonic surface acoustic wave fields using extrinsic Fizeau fiber interferometric (EFFI) sensors are reported. Wave propagation in materials and the fiber sensor elements are briefly discussed. Calibrated experimental results obtained for simulated acoustic emission events on homogeneous metal test specimens are reported and compared to previous results obtained using piezoelectric transducers.

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

    SciTech Connect

    Saleem, H.; Haque, Q.

    2015-08-15

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

  17. Observations of vertically propagating driven dust acoustic waves: Finite temperature effects

    SciTech Connect

    Williams, Jeremiah D.; Thomas, Edward Jr.; Marcus, Lydia

    2008-04-15

    In this study, the first measurement of the dispersion relationship for a vertically propagating (i.e., parallel to gravity), driven dust acoustic wave is reported. Finite dust temperature effects were observed in the dispersion relation of the dust acoustic wave.

  18. On the generation of internal wave modes by surface waves

    NASA Astrophysics Data System (ADS)

    Harlander, Uwe; Kirschner, Ian; Maas, Christian; Zaussinger, Florian

    2016-04-01

    Internal gravity waves play an important role in the ocean since they transport energy and momentum and the can lead to mixing when they break. Surface waves and internal gravity waves can interact. On the one hand, long internal waves imply a slow varying shear current that modifies the propagation of surface waves. Surface waves generated by the atmosphere can, on the other hand, excite internal waves by nonlinear interaction. Thereby a surface wave packet consisting of two close frequencies can resonate with a low frequency internal wave (Phillips, 1966). From a theoretical point of view, the latter has been studied intensively by using a 2-layer model, i.e. a surface layer with a strong density contrast and an internal layer with a comparable weak density contrast (Ball, 1964; Craig et al., 2010). In the present work we analyse the wave coupling for a continuously stratified fluid using a fully non-linear 2D numerical model (OpenFoam) and compare this with laboratory experiments (see Lewis et al. 1974). Surface wave modes are used as initial condition and the time development of the dominant surface and internal waves are studied by spectral and harmonic analysis. For the simple geometry of a box, the results are compared with analytical spectra of surface and gravity waves. Ball, F.K. 1964: Energy transfer between external and internal gravity waves. J. Fluid Mech. 19, 465. Craig, W., Guyenne, P., Sulem, C. 2010: Coupling between internal and surface waves. Natural Hazards 57, 617-642. Lewis, J.E., Lake, B.M., Ko, D.R.S 1974: On the interaction of internal waves and surfacr gravity waves, J. Fluid Mech. 63, 773-800. Phillips, O.M. 1966: The dynamics of the upper ocean, Cambridge University Press, 336pp.

  19. Dynamic acoustics for the STAR-100. [computer algorithms for time dependent sound waves in jet

    NASA Technical Reports Server (NTRS)

    Bayliss, A.; Turkel, E.

    1979-01-01

    An algorithm is described to compute time dependent acoustic waves in a jet. The method differs from previous methods in that no harmonic time dependence is assumed, thus permitting the study of nonharmonic acoustical behavior. Large grids are required to resolve the acoustic waves. Since the problem is nonstiff, explicit high order schemes can be used. These have been adapted to the STAR-100 with great efficiencies and permitted the efficient solution of problems which would not be feasible on a scalar machine.

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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