WorldWideScience

Sample records for frequency surface acoustic

  1. Multiharmonic Frequency-Chirped Transducers for Surface-Acoustic-Wave Optomechanics

    Science.gov (United States)

    Weiß, Matthias; Hörner, Andreas L.; Zallo, Eugenio; Atkinson, Paola; Rastelli, Armando; Schmidt, Oliver G.; Wixforth, Achim; Krenner, Hubert J.

    2018-01-01

    Wide-passband interdigital transducers are employed to establish a stable phase lock between a train of laser pulses emitted by a mode-locked laser and a surface acoustic wave generated electrically by the transducer. The transducer design is based on a multiharmonic split-finger architecture for the excitation of a fundamental surface acoustic wave and a discrete number of its overtones. Simply by introducing a variation of the transducer's periodicity p , a frequency chirp is added. This combination results in wide frequency bands for each harmonic. The transducer's conversion efficiency from the electrical to the acoustic domain is characterized optomechanically using single quantum dots acting as nanoscale pressure sensors. The ability to generate surface acoustic waves over a wide band of frequencies enables advanced acousto-optic spectroscopy using mode-locked lasers with fixed repetition rate. Stable phase locking between the electrically generated acoustic wave and the train of laser pulses is confirmed by performing stroboscopic spectroscopy on a single quantum dot at a frequency of 320 MHz. Finally, the dynamic spectral modulation of the quantum dot is directly monitored in the time domain combining stable phase-locked optical excitation and time-correlated single-photon counting. The demonstrated scheme will be particularly useful for the experimental implementation of surface-acoustic-wave-driven quantum gates of optically addressable qubits or collective quantum states or for multicomponent Fourier synthesis of tailored nanomechanical waveforms.

  2. Observation of low-frequency acoustic surface waves in the nocturnal boundary layer.

    Science.gov (United States)

    Talmadge, Carrick L; Waxler, Roger; Di, Xiao; Gilbert, Kenneth E; Kulichkov, Sergey

    2008-10-01

    A natural terrain surface, because of its porosity, can support an acoustic surface wave that is a mechanical analog of the familiar vertically polarized surface wave in AM radio transmission. At frequencies of several hundred hertz, the acoustic surface wave is attenuated over distances of a few hundred meters. At lower frequencies (e.g., below approximately 200 Hz) the attenuation is much less, allowing surface waves to propagate thousands of meters. At night, a low-frequency surface wave is generally present at long ranges even when downward refraction is weak. Thus, surface waves represent a ubiquitous nighttime transmission mode that exists even when other transmission modes are weak or absent. Data from recent nighttime field experiments and theoretical calculations are presented, demonstrating the persistence of the surface wave under different meteorological conditions. The low-frequency surface wave described here is the "quasiharmonical" tail observed previously in nighttime measurements but not identified by S. Kulichkov and his colleagues (Chunchuzov, I. P. et al. 1990. "On acoustical impulse propagation in a moving inhomogeneous atmospheric layer," J. Acoust. Soc. Am. 88, 455-461).

  3. Nanoliter-droplet acoustic streaming via ultra high frequency surface acoustic waves.

    Science.gov (United States)

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

    2014-08-06

    The relevant length scales in sub-nanometer amplitude surface acoustic wave-driven acoustic streaming are demonstrated. We demonstrate the absence of any physical limitations preventing the downscaling of SAW-driven internal streaming to nanoliter microreactors and beyond by extending SAW microfluidics up to operating frequencies in the GHz range. This method is applied to nanoliter scale fluid mixing. © 2014 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gelda, Dhruv, E-mail: gelda2@illinois.edu; Sadhu, Jyothi; Ghossoub, Marc G.; Ertekin, Elif [Department of Mechanical Science and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Sinha, Sanjiv [Department of Mechanical Science and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Micro and Nanotechnology Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)

    2016-04-28

    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.

  5. Ultrahigh-frequency surface acoustic wave generation for acoustic charge transport in silicon

    NARCIS (Netherlands)

    Büyükköse, S.; Vratzov, B.; van der Veen, Johan (CTIT); Santos, P.V.; van der Wiel, Wilfred Gerard

    2013-01-01

    We demonstrate piezo-electrical generation of ultrahigh-frequency surface acoustic waves on silicon substrates, using high-resolution UV-based nanoimprint lithography, hydrogen silsequioxane planarization, and metal lift-off. Interdigital transducers were fabricated on a ZnO layer sandwiched between

  6. Nano-optomechanical system based on microwave frequency surface acoustic waves

    Science.gov (United States)

    Tadesse, Semere Ayalew

    Cavity optomechnics studies the interaction of cavity confined photons with mechanical motion. The emergence of sophisticated nanofabrication technology has led to experimental demonstrations of a wide range of novel optomechanical systems that exhibit strong optomechanical coupling and allow exploration of interesting physical phenomena. Many of the studies reported so far are focused on interaction of photons with localized mechanical modes. For my doctoral research, I did experimental investigations to extend this study to propagating phonons. I used surface travelling acoustic waves as the mechanical element of my optomechanical system. The optical cavities constitute an optical racetrack resonator and photonic crystal nanocavity. This dissertation discusses implementation of this surface acoustic wave based optomechanical system and experimental demonstrations of important consequences of the optomechanical coupling. The discussion focuses on three important achievements of the research. First, microwave frequency surface acoustic wave transducers were co-integrated with an optical racetrack resonator on a piezoelectric aluminum nitride film deposited on an oxidized silicon substrate. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength was achieved. The phase and modal matching conditions in this paradigm were investigated for efficient optmechanical coupling. Second, the optomechanical coupling was pushed further into the sideband resolved regime by integrating the high frequency surface acoustic wave transducers with a photonic crystal nanocavity. This device was used to demonstrate optomecahnically induced transparency and absorption, one of the interesting consequences of cavity optomechanics. Phase coherent interaction of the acoustic wave with multiple nanocavities was also explored. In a related experiment, the photonic crystal nanoscavity was placed inside an acoustic

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

    Science.gov (United States)

    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.

  8. High-Frequency Seafloor Acoustics

    CERN Document Server

    Jackson, Darrell R

    2007-01-01

    High-Frequency Seafloor Acoustics is the first book in a new series sponsored by the Office of Naval Research on the latest research in underwater acoustics. This exciting new title provides ready access to experimental data, theory, and models relevant to high-frequency seafloor acoustics and will be of interest to sonar engineers and researchers working in underwater acoustics. The physical characteristics of the seafloor affecting acoustic propagation and scattering are covered, including physical and geoacoustic properties and surface roughness. Current theories for acoustic propagation in sediments are presented along with corresponding models for reflection, scattering, and seafloor penetration. The main text is backed up by an extensive bibliography and technical appendices.

  9. Photonic integrated single-sideband modulator / frequency shifter based on surface acoustic waves

    DEFF Research Database (Denmark)

    Barretto, Elaine Cristina Saraiva; Hvam, Jørn Märcher

    2010-01-01

    Optical frequency shifters are essential components of many systems. In this paper, a compact integrated optical frequency shifter is designed making use of the combination of surface acoustic waves and Mach-Zehnder interferometers. It has a very simple operation setup and can be fabricated...

  10. Resonant surface acoustic wave chemical detector

    Science.gov (United States)

    Brocato, Robert W.; Brocato, Terisse; Stotts, Larry G.

    2017-08-08

    Apparatus for chemical detection includes a pair of interdigitated transducers (IDTs) formed on a piezoelectric substrate. The apparatus includes a layer of adsorptive material deposited on a surface of the piezoelectric substrate between the IDTs, where each IDT is conformed, and is dimensioned in relation to an operating frequency and an acoustic velocity of the piezoelectric substrate, so as to function as a single-phase uni-directional transducer (SPUDT) at the operating frequency. Additionally, the apparatus includes the pair of IDTs is spaced apart along a propagation axis and mutually aligned relative to said propagation axis so as to define an acoustic cavity that is resonant to surface acoustic waves (SAWs) at the operating frequency, where a distance between each IDT of the pair of IDTs ranges from 100 wavelength of the operating frequency to 400 wavelength of the operating frequency.

  11. Band Width of Acoustic Resonance Frequency Relatively Natural Frequency of Fuel Rod Vibration

    Energy Technology Data Exchange (ETDEWEB)

    Proskuryakov, Konstantin Nicolaevich; Moukhine, V.S.; Novikov, K.S.; Galivets, E.Yu. [MPEI - TU, 14, Krasnokazarmennaya str., Moscow, 111250 (Russian Federation)

    2009-06-15

    In flow induced vibrations the fluid flow is the energy source that causes vibration. Acoustic resonance in piping may lead to severe problems due to over-stressing of components or significant losses of efficiency. Steady oscillatory flow in NPP primary loop can be induced by the pulsating flow introduced by reactor circulating pump or may be set up by self-excitation. Dynamic forces generated by the turbulent flow of coolant in reactor cores cause fuel rods (FR) and fuel assembly (FA) to vibrate. Flow-induced FR and FA vibrations can generally be broken into three groups: large amplitude 'resonance type' vibrations, which can cause immediate rod failure or severe damage to the rod and its support structure, middle amplitude 'within bandwidth of resonance frequency type' vibrations responsible for more gradual wear and fatigue at the contact surface between the fuel cladding and rod support and small amplitude vibrations, 'out of bandwidth of resonance frequency type' responsible for permissible wear and fatigue at the contact surface between the fuel cladding and rod support. Ultimately, these vibration types can result in a cladding breach, and therefore must be accounted for in the thermal hydraulic design of FR and FA and reactor internals. In paper the technique of definition of quality factor (Q) of acoustic contour of the coolant is presented. The value of Q defines a range of frequencies of acoustic fluctuations of the coolant within which the resonance of oscillations of the structure and the coolant is realized. Method of evaluation of so called band width (BW) of acoustic resonance frequency is worked out and presented in the paper. BW characterises the range of the frequency of coolant pressure oscillations within which the frequency of coolant pressure oscillations matches the fuel assembly's natural frequency of vibration (its resonance frequency). Paper show the way of detuning acoustic resonance from natural

  12. Tunable coupled surface acoustic cavities

    Science.gov (United States)

    de Lima, M. M.; Santos, P. V.; Kosevich, Yu. A.; Cantarero, A.

    2012-06-01

    We demonstrate the electric tuning of the acoustic field in acoustic microcavities (MCs) defined by a periodic arrangement of metal stripes within a surface acoustic delay line on LiNbO3 substrate. Interferometric measurements show the enhancement of the acoustic field distribution within a single MC, the presence of a "bonding" and "anti-bonding" modes for two strongly coupled MCs, as well as the positive dispersion of the "mini-bands" formed by five coupled MCs. The frequency and amplitude of the resonances can be controlled by the potential applied to the metal stripes.

  13. Interaction of surface plasmon polaritons and acoustic waves inside an acoustic cavity.

    Science.gov (United States)

    Khokhlov, Nikolai; Knyazev, Grigoriy; Glavin, Boris; Shtykov, Yakov; Romanov, Oleg; Belotelov, Vladimir

    2017-09-15

    In this Letter, we introduce an approach for manipulation of active plasmon polaritons via acoustic waves at sub-terahertz frequency range. The acoustic structures considered are designed as phononic Fabry-Perot microresonators where mirrors are presented with an acoustic superlattice and the structure's surface, and a plasmonic grating is placed on top of the acoustic cavity so formed. It provides phonon localization in the vicinity of the plasmonic grating at frequencies within the phononic stop band enhancing phonon-light interaction. We consider phonon excitation by shining a femtosecond laser pulse on the plasmonic grating. Appropriate theoretical model was used to describe the acoustic process caused by the pump laser pulse in the GaAs/AlAs-based acoustic cavity with a gold grating on top. Strongest modulation is achieved upon excitation of propagating surface plasmon polaritons and hybridization of propagating and localized plasmons. The relative changes in the optical reflectivity of the structure are more than an order of magnitude higher than for the structure without the plasmonic film.

  14. High-frequency acoustic charge transport in GaAs nanowires

    NARCIS (Netherlands)

    Büyükköse, S.; Hernandez-Minguez, A.; Vratzov, B.; Somaschini, C.; Geelhaar, L.; Riechert, H.; van der Wiel, Wilfred Gerard; Santos, P.V.

    2014-01-01

    The oscillating piezoelectric fields accompanying surface acoustic waves are able to transport charge carriers in semiconductor heterostructures. Here, we demonstrate high-frequency (above 1 GHz) acoustic charge transport in GaAs-based nanowires deposited on a piezoelectric substrate. The short

  15. Frequency Representation: Visualization and Clustering of Acoustic Data Using Self-Organizing Maps.

    Science.gov (United States)

    Guo, Xinhua; Sun, Song; Yu, Xiantao; Wang, Pan; Nakamura, Kentaro

    2017-11-01

    Extraction and display of frequency information in three-dimensional (3D) acoustic data are important steps to analyze object characteristics, because the characteristics, such as profiles, sizes, surface structures, and material properties, may show frequency dependence. In this study, frequency representation (FR) based on phase information in multispectral acoustic imaging (MSAI) is proposed to overcome the limit of intensity or amplitude information in image display. Experiments are performed on 3D acoustic data collected from a rigid surface engraved with five different letters. The results show that the proposed FR technique can not only identify the depth of the five letters by the colors representing frequency characteristics but also demonstrate the 3D image of the five letters, providing more detailed characteristics that are unavailable by conventional acoustic imaging.

  16. Surface acoustic wave coding for orthogonal frequency coded devices

    Science.gov (United States)

    Malocha, Donald (Inventor); Kozlovski, Nikolai (Inventor)

    2011-01-01

    Methods and systems for coding SAW OFC devices to mitigate code collisions in a wireless multi-tag system. Each device producing plural stepped frequencies as an OFC signal with a chip offset delay to increase code diversity. A method for assigning a different OCF to each device includes using a matrix based on the number of OFCs needed and the number chips per code, populating each matrix cell with OFC chip, and assigning the codes from the matrix to the devices. The asynchronous passive multi-tag system includes plural surface acoustic wave devices each producing a different OFC signal having the same number of chips and including a chip offset time delay, an algorithm for assigning OFCs to each device, and a transceiver to transmit an interrogation signal and receive OFC signals in response with minimal code collisions during transmission.

  17. Low frequency acoustic properties of bilayer membrane acoustic metamaterial with magnetic oscillator

    Directory of Open Access Journals (Sweden)

    Nansha Gao

    2017-07-01

    Full Text Available A bilayer membrane acoustic metamaterial was proposed to overcome the influence of the mass law on traditional acoustic materials and obtain a lightweight thin-layer structure that can effectively isolate low frequency noise. The finite element analysis (FEA results agree well with the experimental results. It is proved that the sound transmission losses (STLs of the proposed structures are higher than those of same surface density acoustic materials. The introduction of the magnetic mass block is different from the traditional design method, in which only a passive mass block is fixed on the membrane. The magnetic force will cause tension in the membrane, increase membrane prestress, and improve overall structural stiffness. The effects of the geometry size on the STLs are discussed in detail. The kind of method presented in this paper can provide a new means for engineering noise control. Keywords: Bilayer membrane acoustic metamaterial, Low frequency sound insulation, Sound transmission loss, Magnet oscillator

  18. Frequency effects on the scale and behavior of acoustic streaming.

    Science.gov (United States)

    Dentry, Michael B; Yeo, Leslie Y; Friend, James R

    2014-01-01

    Acoustic streaming underpins an exciting range of fluid manipulation phenomena of rapidly growing significance in microfluidics, where the streaming often assumes the form of a steady, laminar jet emanating from the device surface, driven by the attenuation of acoustic energy within the beam of sound propagating through the liquid. The frequencies used to drive such phenomena are often chosen ad hoc to accommodate fabrication and material issues. In this work, we seek a better understanding of the effects of sound frequency and power on acoustic streaming. We present and, using surface acoustic waves, experimentally verify a laminar jet model that is based on the turbulent jet model of Lighthill, which is appropriate for acoustic streaming seen at micro- to nanoscales, between 20 and 936 MHz and over a broad range of input power. Our model eliminates the critically problematic acoustic source singularity present in Lighthill's model, replacing it with a finite emission area and enabling determination of the streaming velocity close to the source. At high acoustic power P (and hence high jet Reynolds numbers ReJ associated with fast streaming), the laminar jet model predicts a one-half power dependence (U∼P1/2∼ ReJ) similar to the turbulent jet model. However, the laminar model may also be applied to jets produced at low powers-and hence low jet Reynolds numbers ReJ-where a linear relationship between the beam power and streaming velocity exists: U∼P∼ReJ2. The ability of the laminar jet model to predict the acoustic streaming behavior across a broad range of frequencies and power provides a useful tool in the analysis of microfluidics devices, explaining peculiar observations made by several researchers in the literature. In particular, by elucidating the effects of frequency on the scale of acoustically driven flows, we show that the choice of frequency is a vitally important consideration in the design of small-scale devices employing acoustic streaming

  19. Estimating propagation velocity through a surface acoustic wave sensor

    Science.gov (United States)

    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.

  20. Responsive acoustic surfaces

    DEFF Research Database (Denmark)

    Peters, Brady; Tamke, Martin; Nielsen, Stig Anton

    2011-01-01

    Acoustic performance is defined by the parameter of reverberation time; however, this does not capture the acoustic experience in some types of open plan spaces. As many working and learning activities now take place in open plan spaces, it is important to be able to understand and design...... for the acoustic conditions of these spaces. This paper describes an experimental research project that studied the design processes necessary to design for sound. A responsive acoustic surface was designed, fabricated and tested. This acoustic surface was designed to create specific sonic effects. The design...... was simulated using custom integrated acoustic software and also using Odeon acoustic analysis software. The research demonstrates a method for designing space- and sound-defining surfaces, defines the concept of acoustic subspace, and suggests some new parameters for defining acoustic subspaces....

  1. Anisotropic surface acoustic waves in tungsten/lithium niobate phononic crystals

    Science.gov (United States)

    Sun, Jia-Hong; Yu, Yuan-Hai

    2018-02-01

    Phononic crystals (PnC) were known for acoustic band gaps for different acoustic waves. PnCs were already applied in surface acoustic wave (SAW) devices as reflective gratings based on the band gaps. In this paper, another important property of PnCs, the anisotropic propagation, was studied. PnCs made of circular tungsten films on a lithium niobate substrate were analyzed by finite element method. Dispersion curves and equal frequency contours of surface acoustic waves in PnCs of various dimensions were calculated to study the anisotropy. The non-circular equal frequency contours and negative refraction of group velocity were observed. Then PnC was applied as an acoustic lens based on the anisotropic propagation. Trajectory of SAW passing PnC lens was calculated and transmission of SAW was optimized by selecting proper layers of lens and applying tapered PnC. The result showed that PnC lens can suppress diffraction of surface waves effectively and improve the performance of SAW devices.

  2. Distributed feedback guided surface acoustic wave microresonator

    Science.gov (United States)

    Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

    1989-08-01

    Surface acoustic wave resonators have been used in a number of applications: high-Q frequency filtering, very accurate frequency sources, etc. A major disadvantage of conventional resonators is their large dimensions, which makes them inadequate for integrated acoustics applications. In order to overcome these size limitations a new type of microresonator was designed, developed, and tested. In this paper, theoretical calculations and measurements on two kinds of such devices (a corrugated waveguide filter and a microresonator structure) are presented and their possible applications are discussed.

  3. Measured wavenumber: frequency spectrum associated with acoustic and aerodynamic wall pressure fluctuations.

    Science.gov (United States)

    Arguillat, Blandine; Ricot, Denis; Bailly, Christophe; Robert, Gilles

    2010-10-01

    Direct measurements of the wavenumber-frequency spectrum of wall pressure fluctuations beneath a turbulent plane channel flow have been performed in an anechoic wind tunnel. A rotative array has been designed that allows the measurement of a complete map, 63×63 measuring points, of cross-power spectral densities over a large area. An original post-processing has been developed to separate the acoustic and the aerodynamic exciting loadings by transforming space-frequency data into wavenumber-frequency spectra. The acoustic part has also been estimated from a simple Corcos-like model including the contribution of a diffuse sound field. The measured acoustic contribution to the surface pressure fluctuations is 5% of the measured aerodynamic surface pressure fluctuations for a velocity and boundary layer thickness relevant for automotive interior noise applications. This shows that for aerodynamically induced car interior noise, both contributions to the surface pressure fluctuations on car windows have to be taken into account.

  4. Acoustic tweezing of particles using decaying opposing travelling surface acoustic waves (DOTSAW).

    Science.gov (United States)

    Ng, Jia Wei; Devendran, Citsabehsan; Neild, Adrian

    2017-10-11

    Surface acoustic waves offer a versatile and biocompatible method of manipulating the location of suspended particles or cells within microfluidic systems. The most common approach uses the interference of identical frequency, counter propagating travelling waves to generate a standing surface acoustic wave, in which particles migrate a distance less than half the acoustic wavelength to their nearest pressure node. The result is the formation of a periodic pattern of particles. Subsequent displacement of this pattern, the prerequisite for tweezing, can be achieved by translation of the standing wave, and with it the pressure nodes; this requires changing either the frequency of the pair of waves, or their relative phase. Here, in contrast, we examine the use of two counterpropagating traveling waves of different frequency. The non-linearity of the acoustic forces used to manipulate particles, means that a small frequency difference between the two waves creates a substantially different force field, which offers significant advantages. Firstly, this approach creates a much longer range force field, in which migration takes place across multiple wavelengths, and causes particles to be gathered together in a single trapping site. Secondly, the location of this single trapping site can be controlled by the relative amplitude of the two waves, requiring simply an attenuation of one of the electrical drive signals. Using this approach, we show that by controlling the powers of the opposing incoherent waves, 5 μm particles can be migrated laterally across a fluid flow to defined locations with an accuracy of ±10 μm.

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

    Science.gov (United States)

    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.

  6. Scattering from objects and surfaces in room acoustical simulations

    DEFF Research Database (Denmark)

    Marbjerg, Gerd Høy; Brunskog, Jonas; Jeong, Cheol-Ho

    2016-01-01

    been implemented in the simulation tool PARISM (Phased Acoustical Radiosity and Image Source Method). Scattering from objects and surfaces is likely to be strongly frequency dependent and the frequency dependence can depend on their sizes, shapes and structure. The importance of the frequency...

  7. Picosecond ultrasonic study of surface acoustic waves on periodically patterned layered nanostructures.

    Science.gov (United States)

    Colletta, Michael; Gachuhi, Wanjiru; Gartenstein, Samuel A; James, Molly M; Szwed, Erik A; Daly, Brian C; Cui, Weili; Antonelli, George A

    2018-07-01

    We have used the ultrafast pump-probe technique known as picosecond ultrasonics to generate and detect surface acoustic waves on a structure consisting of nanoscale Al lines on SiO 2 on Si. We report results from ten samples with varying pitch (1000-140 nm) and SiO 2 film thickness (112 nm or 60 nm), and compare our results to an isotropic elastic calculation and a coarse-grained molecular dynamics simulation. In all cases we are able to detect and identify a Rayleigh-like surface acoustic wave with wavelength equal to the pitch of the lines and frequency in the range of 5-24 GHz. In some samples, we are able to detect additional, higher frequency surface acoustic waves or independent modes of the Al lines with frequencies close to 50 GHz. We also describe the effects of probe beam polarization on the measurement's sensitivity to the different surface modes. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Nonlinear acoustic effects in the propagation of surface acoustic waves in SrTiO3 near the structural phase transition

    International Nuclear Information System (INIS)

    Balashova, E.V.; Lemanov, V.V.; Sherman, A.B.

    1986-01-01

    Generation process of a surface acoustic wave with summarized frequency in collinear propagation of two surface acoustic waves in SrTiO 3 crystal near crystal-phase transition O n → D 4h (T c ≅ 105 K) is investigated. Anomalous increase of a nonlinear parameter Γ ∼ (T-T c ) -1 attributed to a fluctuation mechanism is observed. It is shown that the presence of a surface layer in SrTiO 3 having a higher, than in crystal volume, temperature of phase transition results in summarized frequency signal oscillation

  9. A lightweight low-frequency sound insulation membrane-type acoustic metamaterial

    Directory of Open Access Journals (Sweden)

    Kuan Lu

    2016-02-01

    Full Text Available A novel membrane-type acoustic metamaterial with a high sound transmission loss (STL at low frequencies (⩽500Hz was designed and the mechanisms were investigated by using negative mass density theory. This metamaterial’s structure is like a sandwich with a thin (thickness=0.25mm lightweight flexible rubber material within two layers of honeycomb cell plates. Negative mass density was demonstrated at frequencies below the first natural frequency, which results in the excellent low-frequency sound insulation. The effects of different structural parameters of the membrane on the sound-proofed performance at low frequencies were investigated by using finite element method (FEM. The numerical results show that, the STL can be modulated to higher value by changing the structural parameters, such as the membrane surface density, the unite cell film shape, and the membrane tension. The acoustic metamaterial proposed in this study could provide a potential application in the low-frequency noise insulation.

  10. A lightweight low-frequency sound insulation membrane-type acoustic metamaterial

    Science.gov (United States)

    Lu, Kuan; Wu, Jiu Hui; Guan, Dong; Gao, Nansha; Jing, Li

    2016-02-01

    A novel membrane-type acoustic metamaterial with a high sound transmission loss (STL) at low frequencies (⩽500Hz) was designed and the mechanisms were investigated by using negative mass density theory. This metamaterial's structure is like a sandwich with a thin (thickness=0.25mm) lightweight flexible rubber material within two layers of honeycomb cell plates. Negative mass density was demonstrated at frequencies below the first natural frequency, which results in the excellent low-frequency sound insulation. The effects of different structural parameters of the membrane on the sound-proofed performance at low frequencies were investigated by using finite element method (FEM). The numerical results show that, the STL can be modulated to higher value by changing the structural parameters, such as the membrane surface density, the unite cell film shape, and the membrane tension. The acoustic metamaterial proposed in this study could provide a potential application in the low-frequency noise insulation.

  11. Localized Acoustic Surface Modes

    KAUST Repository

    Farhat, Mohamed

    2015-08-04

    We introduce the concept of localized acoustic surface modes (ASMs). We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

  12. Frequency hopping due to acousto-electric interaction in ZnO based surface acoustic wave oscillator

    Science.gov (United States)

    Dasgupta, Daipayan; Sreenivas, K.

    2011-08-01

    A 36 MHz surface acoustic wave delay line based oscillator has been used to study the effect of acousto-electric interaction due to photo generated charge carriers in rf sputtered ZnO film under UV illumination (λ = 365 nm, 20-100 μW/cm2). Design aspects for developing a delay line based SAW oscillator are specified. The observed linear downshift in frequency (2.2 to 19.0 kHz) with varying UV intensity (20-100 μW/cm2) is related to the fractional velocity change due to acousto-electric interaction. UV illumination level of 100 μW/cm2 leads to a characteristic frequency hopping behavior arising due to a change in the oscillation criteria, and is attributed to the complex interplay between the increased attenuation and velocity shift.

  13. High frequency time modulation of neutrons by LiNbO3 crystals with surface acoustic waves excited under the diffraction condition

    International Nuclear Information System (INIS)

    Takahashi, Toshio; Granzer, E.; Kikuta, Seishi; Tomimitsu, Hiroshi; Doi, Kenji.

    1985-01-01

    High frequency time modulation of neutrons was investigated by using Y-cut LiNbO 3 crystals with surface acoustic waves excited. A double crystal arrangement of (+, -) parallel setting was used for 030 symmetric Bragg-case reflections. Synchronized standing waves with a resonance frequency of 14.26 MHz were excited on the both crystals. Variation of the diffracted intensity with phase difference between two standing waves was studied. The result showed an intensity change of diffracted neutrons with twice the resonance frequency. (author)

  14. A highly attenuating and frequency tailorable annular hole phononic crystal for surface acoustic waves.

    Science.gov (United States)

    Ash, B J; Worsfold, S R; Vukusic, P; Nash, G R

    2017-08-02

    Surface acoustic wave (SAW) devices are widely used for signal processing, sensing and increasingly for lab-on-a-chip applications. Phononic crystals can control the propagation of SAW, analogous to photonic crystals, enabling components such as waveguides and cavities. Here we present an approach for the realisation of robust, tailorable SAW phononic crystals, based on annular holes patterned in a SAW substrate. Using simulations and experiments, we show that this geometry supports local resonances which create highly attenuating phononic bandgaps at frequencies with negligible coupling of SAWs into other modes, even for relatively shallow features. The enormous bandgap attenuation is up to an order-of-magnitude larger than that achieved with a pillar phononic crystal of the same size, enabling effective phononic crystals to be made up of smaller numbers of elements. This work transforms the ability to exploit phononic crystals for developing novel SAW device concepts, mirroring contemporary progress in photonic crystals.The control and manipulation of propagating sound waves on a surface has applications in on-chip signal processing and sensing. Here, Ash et al. deviate from standard designs and fabricate frequency tailorable phononic crystals with an order-of-magnitude increase in attenuation.

  15. Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Ai, Ye

    2016-05-17

    Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

  16. Optimizing surface acoustic wave sensors for trace chemical detection

    Energy Technology Data Exchange (ETDEWEB)

    Frye, G.C.; Kottenstette, R.J.; Heller, E.J. [and others

    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.

  17. Nonlinear frequency shift of a coherent dust-acoustic wave in the presence of dust-acoustic turbulence

    International Nuclear Information System (INIS)

    Yi Sumin; Ryu, C.-M.; Yoon, Peter H.

    2003-01-01

    The nonlinear frequency shift of a low-frequency, coherent dust-acoustic wave in the presence of higher frequency dust-acoustic turbulence is investigated in the framework of weak turbulence theory. It is found that the frequency shift of the dust-acoustic wave in an unmagnetized dusty plasma is always positive irrespective of the propagation direction of the coherent wave. It is also found that turbulent waves propagating in the same direction as the coherent wave are shown to give rise to a much higher frequency shift than the opposite case. Finally, it is shown that the nonlinear frequency shift of a dust-acoustic wave is more pronounced than in the case of the customary ion-acoustic waves in fully ionized plasmas

  18. Surface acoustic waves voltage controlled directional coupler

    Science.gov (United States)

    Golan, G.; Griffel, G.; Yanilov, E.; Ruschin, S.; Seidman, A.; Croitoru, N.

    1988-10-01

    An important condition for the development of surface wave integrated-acoustic devices is the ability to guide and control the propagation of the acoustic energy. This can be implemented by deposition of metallic "loading" channels on an anisotropic piezoelectric substrate. Deposition of such two parallel channels causes an effective coupling of acoustic energy from one channel to the other. A basic requirement for this coupling effect is the existence of the two basic modes: a symmetrical and a nonsymmetrical one. A mode map that shows the number of sustained modes as a function of the device parameters (i.e., channel width; distance between channels; material velocity; and acoustical exciting frequency) is presented. This kind of map can help significantly in the design process of such a device. In this paper we devise an advanced acoustical "Y" coupler with the ability to control its effective coupling by an externally applied voltage, thereby causing modulation of the output intensities of the signals.

  19. Acoustic characteristics of bubble bursting at the surface of a high-viscosity liquid

    International Nuclear Information System (INIS)

    Liu Xiao-Bo; Zhang Jian-Run; Li Pu

    2012-01-01

    An acoustic pressure model of bubble bursting is proposed. An experiment studying the acoustic characteristics of the bursting bubble at the surface of a high-viscosity liquid is reported. It is found that the sudden bursting of a bubble at the high-viscosity liquid surface generates N-shape wave at first, then it transforms into a jet wave. The fundamental frequency of the acoustic signal caused by the bursting bubble decreases linearly as the bubble size increases. The results of the investigation can be used to understand the acoustic characteristics of bubble bursting. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  20. Characterization of microchannel anechoic corners formed by surface acoustic waves

    Science.gov (United States)

    Destgeer, Ghulam; Alam, Ashar; Ahmed, Husnain; Park, Jinsoo; Jung, Jin Ho; Park, Kwangseok; Sung, Hyung Jin

    2018-02-01

    Surface acoustic waves (SAWs) generated in a piezoelectric substrate couple with a liquid according to Snell's law such that a compressional acoustic wave propagates obliquely at a Rayleigh angle ( θ t) inside the microchannel to form a region devoid of a direct acoustic field, which is termed a microchannel anechoic corner (MAC). In the present study, we used microchannels with various heights and widths to characterize the width of the MAC region formed by a single travelling SAW. The attenuation of high-frequency SAWs produced a strong acoustic streaming flow that moved the particles in and out of the MAC region, whereas reflections of the acoustic waves within the microchannel resulted in standing acoustic waves that trapped particles at acoustic pressure nodes located within or outside of the MAC region. A range of actuation frequencies and particle diameters were used to investigate the effects of the acoustic streaming flow and the direct acoustic radiation forces by the travelling as well as standing waves on the particle motion with respect to the MAC region. The width of the MAC ( w c), measured experimentally by tracing the particles, increased with the height of the microchannel ( h m) according to a simple trigonometric equation w c = h m × tan ( θ t ).

  1. Bayesian-based estimation of acoustic surface impedance: Finite difference frequency domain approach.

    Science.gov (United States)

    Bockman, Alexander; Fackler, Cameron; Xiang, Ning

    2015-04-01

    Acoustic performance for an interior requires an accurate description of the boundary materials' surface acoustic impedance. Analytical methods may be applied to a small class of test geometries, but inverse numerical methods provide greater flexibility. The parameter estimation problem requires minimizing prediction vice observed acoustic field pressure. The Bayesian-network sampling approach presented here mitigates other methods' susceptibility to noise inherent to the experiment, model, and numerics. A geometry agnostic method is developed here and its parameter estimation performance is demonstrated for an air-backed micro-perforated panel in an impedance tube. Good agreement is found with predictions from the ISO standard two-microphone, impedance-tube method, and a theoretical model for the material. Data by-products exclusive to a Bayesian approach are analyzed to assess sensitivity of the method to nuisance parameters.

  2. Acoustic Imaging Frequency Dynamics of Ferroelectric Domains by Atomic Force Microscopy

    International Nuclear Information System (INIS)

    Kun-Yu, Zhao; Hua-Rong, Zeng; Hong-Zhang, Song; Sen-Xing, Hui; Guo-Rong, Li; Qing-Rui, Yin; Shimamura, Kiyoshi; Kannan, Chinna Venkadasamy; Villora, Encarnacion Antonia Garcia; Takekawa, Shunji; Kitamura, Kenji

    2008-01-01

    We report the acoustic imaging frequency dynamics of ferroelectric domains by low-frequency acoustic probe microscopy based on the commercial atomic force microscopy It is found that ferroelectric domain could be firstly visualized at lower frequency down to 0.5 kHz by AFM-based acoustic microscopy The frequency-dependent acoustic signal revealed a strong acoustic response in the frequency range from 7kHz to 10kHz, and reached maximum at 8.1kHz. The acoustic contrast mechanism can be ascribed to the different elastic response of ferroelectric microstructures to local elastic stress fields, which is induced by the acoustic wave transmitting in the sample when the piezoelectric transducer is vibrating and exciting acoustic wave under ac electric fields due to normal piezoelectric effects. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

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

    International Nuclear Information System (INIS)

    Li, L. L.; Xu, W.

    2014-01-01

    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

  4. Dispersion of acoustic surface waves by velocity gradients

    Science.gov (United States)

    Kwon, S. D.; Kim, H. C.

    1987-10-01

    The perturbation theory of Auld [Acoustic Fields and Waves in Solids (Wiley, New York, 1973), Vol. II, p. 294], which describes the effect of a subsurface gradient on the velocity dispersion of surface waves, has been modified to a simpler form by an approximation using a newly defined velocity gradient for the case of isotropic materials. The modified theory is applied to nitrogen implantation in AISI 4140 steel with a velocity gradient of Gaussian profile, and compared with dispersion data obtained by the ultrasonic right-angle technique in the frequency range from 2.4 to 14.8 MHz. The good agreement between experiments and our theory suggests that the compound layer in the subsurface region plays a dominant role in causing the dispersion of acoustic surface waves.

  5. Frequency response improvement of a two-port surface acoustic wave device based on epitaxial AlN thin film

    Science.gov (United States)

    Gao, Junning; Hao, Zhibiao; Luo, Yi; Li, Guoqiang

    2018-01-01

    This paper presents an exploration on improving the frequency response of the symmetrical two-port AlN surface acoustic wave (SAW) device, using epitaxial AlN thin film on (0001) sapphire as the piezoelectric substrate. The devices were fabricated by lift-off processes with Ti/Al composite electrodes as interleaved digital transducers (IDT). The impact of DL and the number of the IDT finger pairs on the frequency response was carefully investigated. The overall properties of the device are found to be greatly improved with DL elongation, indicated by the reduced pass band ripple and increased stop band rejection ratio. The rejection increases by 8.3 dB when DL elongates from 15.5λ to 55.5λ and 4.4 dB further accompanying another 50λ elongation. This is because larger DL repels the stray acoustic energy out of the propagation path and provides a cleaner traveling channel for functional SAW, and at the same time restrains electromagnetic feedthrough. It is also found that proper addition of the IDT finger pairs is beneficial for the device response, indicated by the ripple reduction and the insertion loss drop.

  6. Frequency Selection for Multi-frequency Acoustic Measurement of Suspended Sediment

    Science.gov (United States)

    Chen, X.; HO, H.; Fu, X.

    2017-12-01

    Multi-frequency acoustic measurement of suspended sediment has found successful applications in marine and fluvial environments. Difficult challenges remain in regard to improving its effectiveness and efficiency when applied to high concentrations and wide size distributions in rivers. We performed a multi-frequency acoustic scattering experiment in a cylindrical tank with a suspension of natural sands. The sands range from 50 to 600 μm in diameter with a lognormal size distribution. The bulk concentration of suspended sediment varied from 1.0 to 12.0 g/L. We found that the commonly used linear relationship between the intensity of acoustic backscatter and suspended sediment concentration holds only at sufficiently low concentrations, for instance below 3.0 g/L. It fails at a critical value of concentration that depends on measurement frequency and the distance between the transducer and the target point. Instead, an exponential relationship was found to work satisfactorily throughout the entire range of concentration. The coefficient and exponent of the exponential function changed, however, with the measuring frequency and distance. Considering the increased complexity of inverting the concentration values when an exponential relationship prevails, we further analyzed the relationship between measurement error and measuring frequency. It was also found that the inversion error may be effectively controlled within 5% if the frequency is properly set. Compared with concentration, grain size was found to heavily affect the selection of optimum frequency. A regression relationship for optimum frequency versus grain size was developed based on the experimental results.

  7. Measurement of acoustic glitches in solar-type stars from oscillation frequencies observed by Kepler

    Energy Technology Data Exchange (ETDEWEB)

    Mazumdar, A. [Homi Bhabha Centre for Science Education, TIFR, V. N. Purav Marg, Mankhurd, Mumbai 400088 (India); Monteiro, M. J. P. F. G.; Cunha, M. S. [Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Ballot, J. [CNRS, Institut de Recherche en Astrophysique et Planétologie, 14 avenue Edouard Belin, F-31400 Toulouse (France); Antia, H. M. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Basu, S. [Astronomy Department, Yale University, P.O. Box 208101, New Haven, CT 065208101 (United States); Houdek, G.; Silva Aguirre, V.; Christensen-Dalsgaard, J.; Metcalfe, T. S. [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Mathur, S. [High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO 80307 (United States); García, R. A. [Laboratoire AIM, CEA/DSM, CNRS, Université Paris Diderot, IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Salabert, D. [Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d' Azur, F-06304 Nice (France); Verner, G. A.; Chaplin, W. J. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Sanderfer, D. T. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Seader, S. E.; Smith, J. C. [SETI Institute/NASA Ames Research Center, Moffett Field, CA 94035 (United States)

    2014-02-10

    For the very best and brightest asteroseismic solar-type targets observed by Kepler, the frequency precision is sufficient to determine the acoustic depths of the surface convective layer and the helium ionization zone. Such sharp features inside the acoustic cavity of the star, which we call acoustic glitches, create small oscillatory deviations from the uniform spacing of frequencies in a sequence of oscillation modes with the same spherical harmonic degree. We use these oscillatory signals to determine the acoustic locations of such features in 19 solar-type stars observed by the Kepler mission. Four independent groups of researchers utilized the oscillation frequencies themselves, the second differences of the frequencies and the ratio of the small and large separation to locate the base of the convection zone and the second helium ionization zone. Despite the significantly different methods of analysis, good agreement was found between the results of these four groups, barring a few cases. These results also agree reasonably well with the locations of these layers in representative models of the stars. These results firmly establish the presence of the oscillatory signals in the asteroseismic data and the viability of several techniques to determine the location of acoustic glitches inside stars.

  8. Bubble dynamics under acoustic excitation with multiple frequencies

    International Nuclear Information System (INIS)

    Zhang, Y N; Zhang, Y N; Li, S C

    2015-01-01

    Because of its magnificent mechanical and chemical effects, acoustic cavitation plays an important role in a broad range of biomedical, chemical and mechanical engineering problems. Particularly, irradiation of the multiple frequency acoustic wave could enhance the effects of cavitation. The advantages of employment of multi-frequency ultrasonic field include decreasing the cavitation thresholds, promoting cavitation nuclei generation, increasing the mass transfer and improving energy efficiency. Therefore, multi-frequency ultrasonic systems are employed in a variety of applications, e.g., to enhance the intensity of sonoluminenscence, to increase efficiency of sonochemical reaction, to improve the accuracy of ultrasound imaging and the efficiency of tissue ablation. Compared to single-frequency systems, a lot of new features of bubble dynamics exist in multi-frequency systems, such as special properties of oscillating bubbles, unique resonances in the bubble response curves, and unusual chaotic behaviours. In present paper, the underlying mechanisms of the cavitation effects under multi-frequency acoustical excitation are also briefly introduced

  9. Multi-frequency acoustic metasurface for extraordinary reflection and sound focusing

    Directory of Open Access Journals (Sweden)

    Yi-Fan Zhu

    2016-12-01

    Full Text Available We theoretically and numerically present the design of multi-frequency acoustic metasurfaces (MFAMs with simple structure that can work not only at fundamental frequency, but also at their harmonic frequencies, which breaks the single frequency limitation in conventional resonance-based acoustic metasurfaces. The phase matched condition for achromatic manipulation is discussed. We demonstrate achromatic extraordinary reflection and sound focusing at 1700Hz, 3400Hz, and 5100Hz, that is, they have the same reflection direction and the same focusing position. This significant feature may pave the way to new type of acoustic metasurface, and will also extend acoustic metasurface applications to strongly nonlinear source cases.

  10. Response mechanism for surface acoustic wave gas sensors based on surface-adsorption.

    Science.gov (United States)

    Liu, Jiansheng; Lu, Yanyan

    2014-04-16

    A theoretical model is established to describe the response mechanism of surface acoustic wave (SAW) gas sensors based on physical adsorption on the detector surface. Wohljent's method is utilized to describe the relationship of sensor output (frequency shift of SAW oscillator) and the mass loaded on the detector surface. The Brunauer-Emmett-Teller (BET) formula and its improved form are introduced to depict the adsorption behavior of gas on the detector surface. By combining the two methods, we obtain a theoretical model for the response mechanism of SAW gas sensors. By using a commercial SAW gas chromatography (GC) analyzer, an experiment is performed to measure the frequency shifts caused by different concentration of dimethyl methylphosphonate (DMMP). The parameters in the model are given by fitting the experimental results and the theoretical curve agrees well with the experimental data.

  11. Single-transducer dual-frequency ultrasound generation to enhance acoustic cavitation.

    Science.gov (United States)

    Liu, Hao-Li; Hsieh, Chao-Ming

    2009-03-01

    Dual- or multiple-frequency ultrasound stimulation is capable of effectively enhancing the acoustic cavitation effect over single-frequency ultrasound. Potential application of this sonoreactor design has been widely proposed such as on sonoluminescence, sonochemistry enhancement, and transdermal drug release enhancement. All currently available sonoreactor designs employed multiple piezoelectric transducers for generating single-frequency ultrasonic waves separately and then these waves were mixed and interfered in solutions. The purpose of this research is to propose a novel design of generating dual-frequency ultrasonic waves with single piezoelectric elements, thereby enhancing acoustic cavitation. Macroscopic bubbles were detected optically, and they were quantified at either a single-frequency or for different frequency combinations for determining their efficiency for enhancing acoustic cavitation. Visible bubbles were optically detected and hydrogen peroxide was measured to quantify acoustic cavitation. Test water samples with different gas concentrations and different power levels were used to determine the efficacy of enhancing acoustic cavitation of this design. The spectrum obtained from the backscattered signals was also recorded and examined to confirm the occurrence of stable cavitation. The results confirmed that single-element dual-frequency ultrasound stimulation can enhance acoustic cavitation. Under certain testing conditions, the generation of bubbles can be enhanced up to a level of five times higher than the generation of bubbles in single-frequency stimulation, and can increase the hydrogen peroxide production up to an increase of one fold. This design may serve as a useful alternative for future sonoreactor design owing to its simplicity to produce dual- or multiple-frequency ultrasound.

  12. Implementation of acoustic demultiplexing with membrane-type metasurface in low frequency range

    Science.gov (United States)

    Chen, Xing; Liu, Peng; Hou, Zewei; Pei, Yongmao

    2017-04-01

    Wavelength division multiplexing technology, adopted to increase the information density, plays a significant role in optical communication. However, in acoustics, a similar function can be hardly implemented due to the weak dispersion in natural acoustic materials. Here, an acoustic demultiplexer, based on the concept of metasurfaces, is proposed for splitting acoustic waves and propagating along different trajectories in a low frequency range. An acoustic metasurface, containing multiple resonant units, is designed with various phase profiles for different frequencies. Originating from the highly dispersive properties, the resonant units are independent and merely work in the vicinity of their resonant frequencies. Therefore, by combing multiple resonant units appropriately, the phenomena of anomalous reflection, acoustic focusing, and acoustic wave bending can occur in different frequencies. The proposed acoustic demultiplexer has advantages on the subwavelength scale and the versatility in wave control, providing a strategy for separating acoustic waves with different Fourier components.

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

    Science.gov (United States)

    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.

  14. Effect of surface parameter of interband surface mode frequencies of finite diatomic chain

    International Nuclear Information System (INIS)

    Puszkarski, H.

    1982-07-01

    The surface modes of a finite diatomic chain of alternating atoms (M 1 not= M 2 ) are investigated. The surface force constants are assumed to differ from the bulk ones, with the resulting surface parameter a-tilde identical on both ends of the chain. Criteria, governing the existence of interband surface (IBS) modes with frequencies lying in the forbidden gap between acoustical and optical bulk bands for natural (a = 1) as well as non-natural (a not= 1) surface defect, are analysed by the difference equation method. It is found that the IBS modes localize, depending on the value of the surface parameter a, either at the surface of lighter atoms (if a-tilde is positive), or at that of heavier atoms (if a-tilde is negative). Two, one of no IBS modes are found to exist in the chain depending on the relation between the mass ratio and surface parameter - quantities on which the surface localization increment t-tilde depends. If two modes are present (one acoustical and the other optical), their frequencies are disposed symmetrically with respect to the middle of the forbidden gap, provided the surface defect is natural, or asymmetrically - if it is other than natural. If the localization of the IBS mode exceeds a well defined critical value tsub(c), the mode frequency becomes complex, indicating that the mode undergoes a damping. A comparison of the present results and those obtained by Wallis for the diatomic chain with natural surface defect is also given. (author)

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

    International Nuclear Information System (INIS)

    Sun Hongxiang; Zhang Shuyi; Xu Baiqiang

    2011-01-01

    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. A differential optical interferometer for measuring short pulses of surface acoustic waves.

    Science.gov (United States)

    Shaw, Anurupa; Teyssieux, Damien; Laude, Vincent

    2017-09-01

    The measurement of the displacements caused by the propagation of a short pulse of surface acoustic waves on a solid substrate is investigated. A stabilized time-domain differential interferometer is proposed, with the surface acoustic wave (SAW) sample placed outside the interferometer. Experiments are conducted with surface acoustic waves excited by a chirped interdigital transducer on a piezoelectric lithium niobate substrate having an operational bandwidth covering the 200-400MHz frequency range and producing 10-ns pulses with 36nm maximum out-of-plane displacement. The interferometric response is compared with a direct electrical measurement obtained with a receiving wide bandwidth interdigital transducer and good correspondence is observed. The effects of varying the path difference of the interferometer and the measurement position on the surface are discussed. Pulse compression along the chirped interdigital transducer is observed experimentally. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Propagation of high frequency electrostatic surface waves along the planar interface between plasma and dusty plasma

    Science.gov (United States)

    Mishra, Rinku; Dey, M.

    2018-04-01

    An analytical model is developed that explains the propagation of a high frequency electrostatic surface wave along the interface of a plasma system where semi-infinite electron-ion plasma is interfaced with semi-infinite dusty plasma. The model emphasizes that the source of such high frequency waves is inherent in the presence of ion acoustic and dust ion acoustic/dust acoustic volume waves in electron-ion plasma and dusty plasma region. Wave dispersion relation is obtained for two distinct cases and the role of plasma parameters on wave dispersion is analyzed in short and long wavelength limits. The normalized surface wave frequency is seen to grow linearly for lower wave number but becomes constant for higher wave numbers in both the cases. It is observed that the normalized frequency depends on ion plasma frequencies when dust oscillation frequency is neglected.

  18. High-frequency modulation of ion-acoustic waves.

    Science.gov (United States)

    Albright, N. W.

    1972-01-01

    A large amplitude, high-frequency electromagnetic oscillation is impressed on a nonrelativistic, collisionless plasma from an external source. The frequency is chosen to be far from the plasma frequency (in fact, lower). The resulting electron velocity distribution function strongly modifies the propagation of ion-acoustic waves parallel to the oscillating electric field. The complex frequency is calculated numerically.

  19. The near-field acoustic levitation for spheres by transducer with concave spherical radiating surface

    International Nuclear Information System (INIS)

    Liu, Jian Fang; Sun, Xu Guang; Jiao, Xiao Yang; Chen, Hong Xia; Hua, Shun Ming; Zhang, Hong Chun

    2013-01-01

    To levitate ICF target spheres in the near-field acoustic levitation, a transducer with concave spherical radiating surface and a nearfield acoustic levitation system is established. The concave spherical radiating surface of the transducer is designed by the finite element parametric method. Then the levitation height and levitation perturbation of spheres with different mass and diameters in the near-field acoustic levitation system are tested and discussed in the driving voltage at 400V, 500V and 600V, respectively, when the levitation system is under the resonant frequency. Finally, based on the experimental results, the height formula of the near-field acoustic levitation for spheres is deduced by introducing a coupling coefficient.

  20. The near-field acoustic levitation for spheres by transducer with concave spherical radiating surface

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jian Fang; Sun, Xu Guang; Jiao, Xiao Yang; Chen, Hong Xia [Jilin University, Changchun (China); Hua, Shun Ming [Zhejiang University, Ningbo (China); Zhang, Hong Chun [Aviation University of AirForce, Changchun (China)

    2013-02-15

    To levitate ICF target spheres in the near-field acoustic levitation, a transducer with concave spherical radiating surface and a nearfield acoustic levitation system is established. The concave spherical radiating surface of the transducer is designed by the finite element parametric method. Then the levitation height and levitation perturbation of spheres with different mass and diameters in the near-field acoustic levitation system are tested and discussed in the driving voltage at 400V, 500V and 600V, respectively, when the levitation system is under the resonant frequency. Finally, based on the experimental results, the height formula of the near-field acoustic levitation for spheres is deduced by introducing a coupling coefficient.

  1. The influence of environmental parameters on the optimal frequency in a shallow underwater acoustic channel

    Science.gov (United States)

    Zarnescu, George

    2015-02-01

    In a shallow underwater acoustic channel the delayed replicas of a transmitted signal are mainly due to the interactions with the sea surface and the bottom layer. If a specific underwater region on the globe is considered, for which the sedimentary layer structure is constant across the transmission distance, then the variability of the amplitude-delay profile is determined by daily and seasonal changes of the sound speed profile (SSP) and by weather changes, such as variations of the wind speed. Such a parameter will influence the attenuation at the surface, the noise level and the profile of the sea surface. The temporal variation of the impulse response in a shallow underwater acoustic channel determines the variability of the optimal transmission frequency. If the ways in which the optimal frequency changes can be predicted, then an adaptive analog transceiver can be easily designed for an underwater acoustic modem or it can be found when a communication link has high throughput. In this article it will be highlighted the way in which the amplitude-delay profile is affected by the sound speed profile, wind speed and channel depth and also will be emphasized the changes of the optimal transmission frequency in a configuration, where the transmitter and receiver are placed on the seafloor and the bathymetry profile will be considered flat, having a given composition.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    We have investigated the response of the acoustoelectric-current driven by a surface-acoustic wave through a quantum point contact in the closed-channel regime. Under proper conditions, the current develops plateaus at integer multiples of ef when the frequency f of the surface-acoustic wave...... or the gate voltage V-g of the point contact is varied. A pronounced 1.1 MHz beat period of the current indicates that the interference of the surface-acoustic wave with reflected waves matters. This is supported by the results obtained after a second independent beam of surface-acoustic wave was added......, traveling in opposite direction. We have found that two sub-intervals can be distinguished within the 1.1 MHz modulation period, where two different sets of plateaus dominate the acoustoelectric-current versus gate-voltage characteristics. In some cases, both types of quantized steps appeared simultaneously...

  3. Photonic Mach-Zehnder modulators driven by surface acoustic waves in AlGaAs technology

    Science.gov (United States)

    Crespo-Poveda, A.; Gargallo, B.; Artundo, I.; Doménech, J. D.; Muñoz, P.; Hey, R.; Biermann, K.; Tahraoui, A.; Santos, P. V.; Cantarero, A.; de Lima, M. M.

    2014-03-01

    In this paper, photonic devices driven by surface acoustic waves and operating in the GHz frequency range are presented. The devices were designed and fabricated in (Al,Ga)As technology. In contrast to previously realized modulators, where part of the light transmission is lost due to destructive interference, in the present devices light only switches paths, avoiding losses. One of the devices presents two output channels with 180°-dephasing synchronization. Odd multiples of the fundamental driving frequency are enabled by adjusting the applied acoustic power. A second and more complex photonic integrated device, based on the acoustic modulation of tunable Arrayed Waveguide Gratings, is also proposed.

  4. Frequency degeneracy of acoustic waves in two-dimensional phononic crystals

    International Nuclear Information System (INIS)

    Darinskii, A N; Le Clezio, E; Feuillard, G

    2007-01-01

    Degeneracies of acoustic wave spectra in 2D phononic crystals (PC) and PC slabs are studied. A PC structure is constituted of parallel steel rods immersed into water and forming the quadratic lattice. Given the projection k z of the wave vector on the direction of rods, the bulk wave spectrum of the infinite PC is a set of frequency surfaces f i (k x , k y ), i = 1,2,..., where k x,y are the components of the wave vector in the plane perpendicular to the rods. An investigation is performed of the shape of frequency surfaces in the vicinity of points (k dx , k dy ), where these surfaces fall into contact. In addition, the evolution of the degeneracy with changing rod radius and cross-section shape is examined. Degeneracy in the spectrum of leaky modes propagating along a single waveguide in a PC slab is also investigated

  5. Surface acoustic load sensing using a face-shear PIN-PMN-PT single-crystal resonator.

    Science.gov (United States)

    Kim, Kyungrim; Zhang, Shujun; Jiang, Xiaoning

    2012-11-01

    Pb(In(0.5)Nb(0.5))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) resonators for surface acoustic load sensing are presented in this paper. Different acoustic loads are applied to thickness mode, thickness-shear mode, and face-shear mode resonators, and the electrical impedances at resonance and anti-resonance frequencies are recorded. More than one order of magnitude higher sensitivity (ratio of electrical impedance change to surface acoustic impedance change) at the resonance is achieved for the face-shear-mode resonator compared with other resonators with the same dimensions. The Krimholtz, Leedom, and Matthaei (KLM) model is used to verify the surface acoustic loading effect on the electrical impedance spectrum of face-shear PIN-PMN-PT single-crystal resonators. The demonstrated high sensitivity of face-shear mode resonators to surface loads is promising for a broad range of applications, including artificial skin, biological and chemical sensors, touch screens, and other touch-based sensors.

  6. Dual-band frequency selective surface with large band separation and stable performance

    International Nuclear Information System (INIS)

    Zhou Hang; Qu Shao-Bo; Lin Bao-Qin; Wang Jia-Fu; Ma Hua; Zhang Jie-Qiu; Peng Wei-Dong; Bai Peng; Wang Xu-Hua; Xu Zhuo

    2012-01-01

    A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  7. A radioisotope-powered surface acoustic wave transponder

    International Nuclear Information System (INIS)

    Tin, S; Lal, A

    2009-01-01

    We demonstrate a 63 Ni radioisotope-powered pulse transponder that has a SAW (surface acoustic wave) device as the frequency transmission frequency selector. Because the frequency is determined by a SAW device, narrowband detection with an identical SAW device enables the possibility for a long-distance RF-link. The SAW transponders can be buried deep into structural constructs such as steel and concrete, where changing batteries or harvesting vibration or EM energy is not a reliable option. RF-released power to radioisotope- released power amplification is 10 8 , even when regulatory safe amounts of 63 Ni are used. Here we have achieved an 800 µW pulse (315 MHz, 10 µs pause) across a 50 Ω load every 3 min, using a 1.5 milli-Ci 63 Ni source

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

    Science.gov (United States)

    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.

  9. The effects of two counterpropagating surface acoustic wave beams on single electron acoustic charge transport

    International Nuclear Information System (INIS)

    He Jianhong; Guo Huazhong; Song Li; Zhang Wei; Gao Jie; Lu Chuan

    2010-01-01

    We present a comprehensive study of the effects of two counterpropagating surface acoustic waves on the acoustoelectric current of single electron transport devices. A significant improvement in the accuracy of current quantization is achieved as a result of an additional surface acoustic wave beam. The experiments reveal the sinusoidally periodical modulation in the acoustoelectric current characteristic as a function of the relative phase of the two surface acoustic wave beams. Besides, by using standing surface acoustic waves, the acoustoelectric current is detected which we consider as the so-called anomalous acoustoelectric current produced by acoustic wave mechanical deformations. This kind current is contributed to one component of the acoustoelectric current in surface acoustic wave device, which could enable us to establish a more adequate description of acoustoelectric effects on single-electron acoustic charge transport.

  10. Controlled rotation and translation of spherical particles or living cells by surface acoustic waves.

    Science.gov (United States)

    Bernard, Ianis; Doinikov, Alexander A; Marmottant, Philippe; Rabaud, David; Poulain, Cédric; Thibault, Pierre

    2017-07-11

    We show experimental evidence of the acoustically-assisted micromanipulation of small objects like solid particles or blood cells, combining rotation and translation, using high frequency surface acoustic waves. This was obtained from the leakage in a microfluidic channel of two standing waves arranged perpendicularly in a LiNbO 3 piezoelectric substrate working at 36.3 MHz. By controlling the phase lag between the emitters, we could, in addition to translation, generate a swirling motion of the emitting surface which, in turn, led to the rapid rotation of spherical polystyrene Janus beads suspended in the channel and of human red and white blood cells up to several rounds per second. We show that these revolution velocities are compatible with a torque caused by the acoustic streaming that develops at the particles surface, like that first described by [F. Busse et al., J. Acoust. Soc. Am., 1981, 69(6), 1634-1638]. This device, based on standard interdigitated transducers (IDTs) adjusted to emit at equal frequencies, opens a way to a large range of applications since it allows the simultaneous control of the translation and rotation of hard objects, as well as the investigation of the response of cells to shear stress.

  11. Frequency degeneracy of acoustic waves in two-dimensional phononic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Darinskii, A N [Institute of Crystallography RAS, Leninskiy pr. 59, Moscow, 119333 (Russian Federation); Le Clezio, E [Universite Francois Rabelais de Tours, ENI Val de Loire, LUSSI, FRE CNRS 2448, rue de la Chocolaterie, BP3410, 41034 Blois (France); Feuillard, G [Universite Francois Rabelais de Tours, ENI Val de Loire, LUSSI, FRE CNRS 2448, rue de la Chocolaterie, BP3410, 41034 Blois (France)

    2007-12-15

    Degeneracies of acoustic wave spectra in 2D phononic crystals (PC) and PC slabs are studied. A PC structure is constituted of parallel steel rods immersed into water and forming the quadratic lattice. Given the projection k{sub z} of the wave vector on the direction of rods, the bulk wave spectrum of the infinite PC is a set of frequency surfaces f{sub i}(k{sub x}, k{sub y}), i = 1,2,..., where k{sub x,y} are the components of the wave vector in the plane perpendicular to the rods. An investigation is performed of the shape of frequency surfaces in the vicinity of points (k{sub dx}, k{sub dy}), where these surfaces fall into contact. In addition, the evolution of the degeneracy with changing rod radius and cross-section shape is examined. Degeneracy in the spectrum of leaky modes propagating along a single waveguide in a PC slab is also investigated.

  12. Surface acoustic wave oxygen pressure sensor

    Science.gov (United States)

    Oglesby, Donald M. (Inventor); Upchurch, Billy T. (Inventor); Leighty, Bradley D. (Inventor)

    1994-01-01

    A transducer for the measurement of absolute gas-state oxygen pressure from pressures of less than 100 Pa to atmospheric pressure (1.01 x 10(exp 5) Pa) is based on a standard surface acoustic wave (SAW) device. The piezoelectric material of the SAW device is coated with a compound which will selectively and reversibly bind oxygen. When oxygen is bound by the coating, the mass of the coating increases by an amount equal to the mass of the bound oxygen. Such an increase in the mass of the coating causes a corresponding decrease in the resonant frequency of the SAW device.

  13. Modulation of photonic structures by surface acoustic waves

    International Nuclear Information System (INIS)

    Mauricio M de Lima Jr; Santos, Paulo V

    2005-01-01

    This paper reviews the interaction between coherently stimulated acoustic phonons in the form of surface acoustic waves with light beams in semiconductor based photonic structures. We address the generation of surface acoustic wave modes in these structures as well as the technological aspects related to control of the propagation and spatial distribution of the acoustic fields. The microscopic mechanisms responsible for the interaction between light and surface acoustic modes in different structures are then reviewed. Particular emphasis is given to the acousto-optical interaction in semiconductor microcavities and its application in photon control. These structures exhibit high optical modulation levels under acoustic excitation and are compatible with integrated light sources and detectors

  14. Bending and splitting of spoof surface acoustic waves through structured rigid surface

    Directory of Open Access Journals (Sweden)

    Sujun Xie

    2018-03-01

    Full Text Available In this paper, we demonstrated that a 90°-bended imaging of spoof surface acoustic waves with subwavelength resolution of 0.316λ can be realized by a 45° prism-shaped surface phononic crystal (SPC, which is composed of borehole arrays with square lattice in a rigid plate. Furthermore, by combining two identical prism-shaped phononic crystal to form an interface (to form a line-defect, the excited spoof surface acoustic waves can be split into bended and transmitted parts. The power ratio between the bended and transmitted surface waves can be tuned arbitrarily by adjusting the defect size. This acoustic system is believed to have potential applications in various multifunctional acoustic solutions integrated by different acoustical devices.

  15. Calibration of acoustic emission transducers

    International Nuclear Information System (INIS)

    Leschek, W.C.

    1976-01-01

    A method is described for calibrating an acoustic emission transducer to be used in a pre-set frequency range. The absolute reception sensitivity of a reference transducer is determined at frequencies selected within the frequency range. The reference transducer and the acoustic emission transducer are put into acoustic communication with the surface of a limited acoustic medium representing an equivalent acoustic load appreciably identical to that of the medium in which the use of the acoustic emission transducer is intended. A blank random acoustic noise is emitted in the acoustic medium in order to establish a diffuse and reverberating sound field, after which the output responses of the reference transducer and of the acoustic emission transducer are obtained with respect to the diffuse and reverberating field, for selected frequencies. The output response of the acoustic emission transducer is compared with that of the reference transducer for the selected frequencies, so as to determine the reception sensitivity of the acoustic emission transducer [fr

  16. Acoustically Induced Microparticle Orbiting and Clustering on a Solid Surface

    Science.gov (United States)

    Abdel-Fattah, A.; Tarimala, S.; Roberts, P. M.

    2008-12-01

    Behavior of colloidal particles in the bulk solution or at interfaces under the effect of high-frequency acoustics is critical to many seemingly different applications ranging from enhanced oil recovery to improved mixing in microfluidic channels and from accelerated contaminant extractions to surface cleaning, drug delivery and microelectronics. It can be detrimental or beneficial, depending on the application. In medical research, flow cytometry and microfluidics, for example, acoustically induced clustering of tracer particles and/or their sticking to the walls of channels, vessels, or tubes often becomes a problem. On the other hand, it can be tailored to enhance processes such as mixing in microfluidic devices, particle separation and sizing, and power generation microdevices. To better understand the underlying mechanisms, microscopic visualization experiments were performed in which polystyrene fluorescent (468/508 nm wavelength) microspheres with a mean diameter of 2.26-µm and density of 1.05 g/cm3, were suspended in either de-ionized water or a 0.1M NaCl solution. The freshly-prepared colloidal suspension was injected into a parallel-plate glass flow cell, which was subjected to high-frequency acoustics (200-500 kHz) through a piezoelectric transducer attached to one of the cell's outer walls. When the suspending medium is de-ionized water, acoustic stimulation of the cell at 313 kHz induced three distinct particle behaviors: 1) entrainment and bulk transport via wavelength-scale Rayleigh streaming, 2) transport via direct radiation forces to concentrate at nodal or anti-nodal planes, and 3) entrapment via boundary layer vorticular microstreaming resulting in mobile particles orbiting deposited particles. This latter phenomenon is intriguing. It occurs at specific frequencies and the shape of the orbits is determined by the applied frequency, whereas the rotation speed is proportional to the applied amplitude. At the higher ionic strength, on the other

  17. High transmission acoustic focusing by impedance-matched acoustic meta-surfaces

    KAUST Repository

    Al Jahdali, Rasha

    2016-01-19

    Impedance is an important issue in the design of acoustic lenses because mismatched impedance is detrimental to real focusing applications. Here, we report two designs of acoustic lenses that focus acoustic waves in water and air, respectively. They are tailored by acoustic meta-surfaces, which are rigid thin plates decorated with periodically distributed sub-wavelength slits. Their respective building blocks are constructed from the coiling-up spaces in water and the layered structures in air. Analytic analysis based on coupled-mode theory and transfer matrix reveals that the impedances of the lenses are matched to those of the background media. With these impedance-matched acoustic lenses, we demonstrate the acoustic focusing effect by finite-element simulations.

  18. High transmission acoustic focusing by impedance-matched acoustic meta-surfaces

    KAUST Repository

    Al Jahdali, Rasha; Wu, Ying

    2016-01-01

    Impedance is an important issue in the design of acoustic lenses because mismatched impedance is detrimental to real focusing applications. Here, we report two designs of acoustic lenses that focus acoustic waves in water and air, respectively. They are tailored by acoustic meta-surfaces, which are rigid thin plates decorated with periodically distributed sub-wavelength slits. Their respective building blocks are constructed from the coiling-up spaces in water and the layered structures in air. Analytic analysis based on coupled-mode theory and transfer matrix reveals that the impedances of the lenses are matched to those of the background media. With these impedance-matched acoustic lenses, we demonstrate the acoustic focusing effect by finite-element simulations.

  19. Surface acoustic wave dust deposition monitor

    Science.gov (United States)

    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.

  20. Estimating surface acoustic impedance with the inverse method.

    Science.gov (United States)

    Piechowicz, Janusz

    2011-01-01

    Sound field parameters are predicted with numerical methods in sound control systems, in acoustic designs of building and in sound field simulations. Those methods define the acoustic properties of surfaces, such as sound absorption coefficients or acoustic impedance, to determine boundary conditions. Several in situ measurement techniques were developed; one of them uses 2 microphones to measure direct and reflected sound over a planar test surface. Another approach is used in the inverse boundary elements method, in which estimating acoustic impedance of a surface is expressed as an inverse boundary problem. The boundary values can be found from multipoint sound pressure measurements in the interior of a room. This method can be applied to arbitrarily-shaped surfaces. This investigation is part of a research programme on using inverse methods in industrial room acoustics.

  1. Low frequency acoustic properties of a honeycomb-silicone rubber acoustic metamaterial

    Science.gov (United States)

    Gao, Nansha; Hou, Hong

    2017-04-01

    In order to overcome the influence of mass law on traditional acoustic materials and obtain a lightweight thin-layer structure which can effectively isolate the low frequency noises, a honeycomb-silicone rubber acoustic metamaterial was proposed. Experimental results show that the sound transmission loss (STL) of acoustic metamaterial in this paper is greatly higher than that of monolayer silicone rubber metamaterial. Based on the band structure, modal shapes, as well as the sound transmission simulation, the sound insulation mechanism of the designed honeycomb-silicone rubber structure was analyzed from a new perspective, which had been validated experimentally. Side length of honeycomb structure and thickness of the unit structure would affect STL in damping control zone. Relevant conclusions and design method provide a new concept for engineering noise control.

  2. Surface Acoustic Wave Devices

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...

  3. Understanding seafloor morphology using remote high frequency acoustic methods: An appraisal to modern techniques and its effectiveness

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.

    Content-Type text/plain; charset=UTF-8 179 Understanding seafloor morphology using remote high frequency acoustic methods: an appraisal to modern techniques and its effectiveness Bishwajit Chakraborty National institute of Oceanography.... The two third of the earth surface i.e. 362 million square km (70 %) is covered by the ocean. In order to understand the seafloor various methods like: application of remote acoustic techniques, seafloor photographic and geological sampling techniques...

  4. An acoustic radiator with integrated cavity and active control of surface vibration

    NARCIS (Netherlands)

    Berkhoff, Arthur; Tajdari, Farnaz

    2017-01-01

    This paper presents a method to realize an acoustic source for low frequencies with relatively small thickness. A honeycomb plate structure which is open on one side combines the radiating surface and the major part of the air cavity. The vibration of the plate is controlled with a decentralized

  5. Spectral element method for elastic and acoustic waves in frequency domain

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Linlin; Zhou, Yuanguo; Wang, Jia-Min; Zhuang, Mingwei [Institute of Electromagnetics and Acoustics, and Department of Electronic Science, Xiamen, 361005 (China); Liu, Na, E-mail: liuna@xmu.edu.cn [Institute of Electromagnetics and Acoustics, and Department of Electronic Science, Xiamen, 361005 (China); Liu, Qing Huo, E-mail: qhliu@duke.edu [Department of Electrical and Computer Engineering, Duke University, Durham, NC, 27708 (United States)

    2016-12-15

    Numerical techniques in time domain are widespread in seismic and acoustic modeling. In some applications, however, frequency-domain techniques can be advantageous over the time-domain approach when narrow band results are desired, especially if multiple sources can be handled more conveniently in the frequency domain. Moreover, the medium attenuation effects can be more accurately and conveniently modeled in the frequency domain. In this paper, we present a spectral-element method (SEM) in frequency domain to simulate elastic and acoustic waves in anisotropic, heterogeneous, and lossy media. The SEM is based upon the finite-element framework and has exponential convergence because of the use of GLL basis functions. The anisotropic perfectly matched layer is employed to truncate the boundary for unbounded problems. Compared with the conventional finite-element method, the number of unknowns in the SEM is significantly reduced, and higher order accuracy is obtained due to its spectral accuracy. To account for the acoustic-solid interaction, the domain decomposition method (DDM) based upon the discontinuous Galerkin spectral-element method is proposed. Numerical experiments show the proposed method can be an efficient alternative for accurate calculation of elastic and acoustic waves in frequency domain.

  6. Circuit quantum acoustodynamics with surface acoustic waves.

    Science.gov (United States)

    Manenti, Riccardo; Kockum, Anton F; Patterson, Andrew; Behrle, Tanja; Rahamim, Joseph; Tancredi, Giovanna; Nori, Franco; Leek, Peter J

    2017-10-17

    The experimental investigation of quantum devices incorporating mechanical resonators has opened up new frontiers in the study of quantum mechanics at a macroscopic level. It has recently been shown that surface acoustic waves (SAWs) can be piezoelectrically coupled to superconducting qubits, and confined in high-quality Fabry-Perot cavities in the quantum regime. Here we present measurements of a device in which a superconducting qubit is coupled to a SAW cavity, realising a surface acoustic version of cavity quantum electrodynamics. We use measurements of the AC Stark shift between the two systems to determine the coupling strength, which is in agreement with a theoretical model. This quantum acoustodynamics architecture may be used to develop new quantum acoustic devices in which quantum information is stored in trapped on-chip acoustic wavepackets, and manipulated in ways that are impossible with purely electromagnetic signals, due to the 10 5 times slower mechanical waves.In this work, Manenti et al. present measurements of a device in which a tuneable transmon qubit is piezoelectrically coupled to a surface acoustic wave cavity, realising circuit quantum acoustodynamic architecture. This may be used to develop new quantum acoustic devices.

  7. Magneto-thermal-acoustic differential-frequency imaging of magnetic nanoparticle with magnetic spatial localization: a theoretical prediction

    Science.gov (United States)

    Piao, Daqing

    2017-02-01

    The magneto-thermo-acoustic effect that we predicted in 2013 refers to the generation of acoustic-pressure wave from magnetic nanoparticle (MNP) when thermally mediated under an alternating magnetic field (AMF) at a pulsed or frequency-chirped application. Several independent experimental studies have since validated magneto-thermoacoustic effect, and a latest report has discovered acoustic-wave generation from MNP at the second-harmonic frequency of the AMF when operating continuously. We propose that applying two AMFs with differing frequencies to MNP will produce acoustic-pressure wave at the summation and difference of the two frequencies, in addition to the two second-harmonic frequencies. Analysis of the specific absorption dynamics of the MNP when exposed to two AMFs of differing frequencies has shown some interesting patterns of acoustic-intensity at the multiple frequency components. The ratio of the acoustic-intensity at the summation-frequency over that of the difference-frequency is determined by the frequency-ratio of the two AMFs, but remains independent of the AMF strengths. The ratio of the acoustic-intensity at the summation- or difference-frequency over that at each of the two second-harmonic frequencies is determined by both the frequency-ratio and the field-strength-ratio of the two AMFs. The results indicate a potential strategy for localization of the source of a continuous-wave magneto-thermalacoustic signal by examining the frequency spectrum of full-field non-differentiating acoustic detection, with the field-strength ratio changed continuously at a fixed frequency-ratio. The practicalities and challenges of this magnetic spatial localization approach for magneto-thermo-acoustic imaging using a simple envisioned set of two AMFs arranged in parallel to each other are discussed.

  8. Modeling of a Surface Acoustic Wave Strain Sensor

    Science.gov (United States)

    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

  9. A low frequency acoustic insulator by using the acoustic metasurface to a Helmholtz resonator

    Science.gov (United States)

    Zhao, Xiang; Cai, Li; Yu, Dianlong; Lu, Zhimiao; Wen, Jihong

    2017-06-01

    Acoustic metasurfaces (AMSs) are able to manipulate wavefronts at an anomalous angle through a subwavelength layer. Their application provide a new way to control sound waves in addition to traditional materials. In this work, we introduced the AMS into the design of a Helmholtz resonator (HR) and studied the acoustic transmission through the modified HR in a pipe with one branch. The variation of sound insulation capacity with the phase gradient of the AMS was studied, and the results show that the AMS can remarkably lower the frequency band of the sound insulation without increasing the size. Our investigation provides a new degree of freedom for acoustic control with a Helmholtz resonator, which is of great significance in acoustic metasurface theory and sound insulation design.

  10. Specularity of longitudinal acoustic phonons at rough surfaces

    Science.gov (United States)

    Gelda, Dhruv; Ghossoub, Marc G.; Valavala, Krishna; Ma, Jun; Rajagopal, Manjunath C.; Sinha, Sanjiv

    2018-01-01

    The specularity of phonons at crystal surfaces is of direct importance to thermal transport in nanostructures and to dissipation in nanomechanical resonators. Wave scattering theory provides a framework for estimating wavelength-dependent specularity, but experimental validation remains elusive. Widely available thermal conductivity data presents poor validation since the involvement of the infinitude of phonon wavelengths in thermal transport presents an underconstrained test for specularity theory. Here, we report phonon specularity by measuring the lifetimes of individual coherent longitudinal acoustic phonon modes excited in ultrathin (36-205 nm) suspended silicon membranes at room temperature over the frequency range ˜20 -118 GHz. Phonon surface scattering dominates intrinsic Akhiezer damping at frequencies ≳60 GHz, enabling measurements of phonon boundary scattering time over wavelengths ˜72 -140 nm . We obtain detailed statistics of the surface roughness at the top and bottom surfaces of membranes using HRTEM imaging. We find that the specularity of the excited modes are in good agreement with solutions of wave scattering only when the TEM statistics are corrected for projection errors. The often-cited Ziman formula for phonon specularity also appears in good agreement with the data, contradicting previous results. This work helps to advance the fundamental understanding of phonon scattering at the surfaces of nanostructures.

  11. High Frequency Acoustic Propagation using Level Set Methods

    Science.gov (United States)

    2007-01-01

    solution of the high frequency approximation to the wave equation. Traditional solutions to the Eikonal equation in high frequency acoustics are...the Eikonal equation derived from the high frequency approximation to the wave equation, ucuH ∇±=∇ )(),( xx , with the nonnegative function c(x...For simplicity, we only consider the case ucuH ∇+=∇ )(),( xx . Two difficulties must be addressed when solving the Eikonal equation in a fixed

  12. Continuous micro-vortex-based nanoparticle manipulation via focused surface acoustic waves.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Han, Jongyoon; Ai, Ye

    2016-12-20

    Despite increasing demand in the manipulation of nanoscale objects for next generation biological and industrial processes, there is a lack of methods for reliable separation, concentration and purification of nanoscale objects. Acoustic methods have proven their utility in contactless manipulation of microscale objects mainly relying on the acoustic radiation effect, though the influence of acoustic streaming has typically prevented manipulation at smaller length scales. In this work, however, we explicitly take advantage of the strong acoustic streaming in the vicinity of a highly focused, high frequency surface acoustic wave (SAW) beam emanating from a series of focused 6 μm substrate wavelength interdigital transducers patterned on a piezoelectric lithium niobate substrate and actuated with a 633 MHz sinusoidal signal. This streaming field serves to focus fluid streamlines such that incoming particles interact with the acoustic field similarly regardless of their initial starting positions, and results in particle displacements that would not be possible with a travelling acoustic wave force alone. This streaming-induced manipulation of nanoscale particles is maximized with the formation of micro-vortices that extend the width of the microfluidic channel even with the imposition of a lateral flow, occurring when the streaming-induced flow velocities are an order of magnitude larger than the lateral one. We make use of this acoustic streaming to demonstrate the continuous and differential focusing of 100 nm, 300 nm and 500 nm particles.

  13. In-plane confinement and waveguiding of surface acoustic waves through line defects in pillars-based phononic crystal

    Directory of Open Access Journals (Sweden)

    Abdelkrim Khelif

    2011-12-01

    Full Text Available We present a theoretical analysis of an in-plane confinement and a waveguiding of surface acoustic waves in pillars-based phononic crystal. The artificial crystal is made up of cylindrical pillars placed on a semi-infinite medium and arranged in a square array. With a well-chosen of the geometrical parameters, this pillars-based system can display two kinds of complete band gaps for guided waves propagating near the surface, a low frequency gap based on locally resonant mode of pillars as well as a higher frequency gap appearing at Bragg scattering regime. In addition, we demonstrate a waveguiding of surface acoustic wave inside an extended linear defect created by removing rows of pillars in the perfect crystal. We discuss the transmission and the polarization of such confined mode appearing in the higher frequency band gap. We highlight the strong similarity of such defect mode and the Rayleigh wave of free surface medium. An efficient finite element analysis is used to simulate the propagation of guided waves through silicon pillars on a silicon substrate.

  14. Simulation and Optimization of Surface Acoustic Wave Devises

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    2007-01-01

    In this paper a method to model the interaction of the mechanical field from a surface acoustic wave and the optical field in the waveguides of a Mach-Zehnder interferometer is presented. The surface acoustic waves are generated by interdigital transducers using a plane strain model...... in effective refractive index introduced in the Mach-Zehnder interferometer arms by the stresses from the surface acoustic wave is calculated. It is shown that the effective refractive index of the fundamental optical mode increases at a surface acoustic wave crest and decreases at a trough. The height...... of a piezoelectric, inhomogeneous material and reflections from the boundaries are avoided by applying perfectly matched layers. The optical modes in the waveguides are modeled by the time-harmonic wave equation for the magnetic field. The two models are coupled using the stress-optical relation and the change...

  15. Variations in frequency content of acoustic emission during extension of HF-1 steel

    International Nuclear Information System (INIS)

    Hartman, W.F.; Kline, R.A.

    1977-01-01

    Acoustic emissions resulting from continuous, dead-weight, tensile loading of quenched and tempered HF-1 steel were analyzed for frequency content. Three distinct frequency spectra were observed. These correspond to microplasticity, plasticity and deformation after recovery. It is shown that frequency analysis of acoustic emission can be a sensitive evaluation technique for assessing structural integrity

  16. Heat Transfer Characteristics of a Focused Surface Acoustic Wave (F-SAW Device for Interfacial Droplet Jetting

    Directory of Open Access Journals (Sweden)

    Donghwi Lee

    2018-06-01

    Full Text Available In this study, we investigate the interfacial droplet jetting characteristics and thermal stability of a focused surface acoustic wave device (F-SAW. An F-SAW device capable of generating a 20 MHz surface acoustic wave by applying sufficient radio frequency power (2–19 W on a 128°-rotated YX-cut piezoelectric lithium niobate substrate for interfacial droplet jetting is proposed. The interfacial droplet jetting characteristics were visualized by a shadowgraph method using a high-speed camera, and a heat transfer experiment was conducted using K-type thermocouples. The interfacial droplet jetting characteristics (jet angle and height were analyzed for two different cases by applying a single interdigital transducer and two opposite interdigital transducers. Surface temperature variations were analyzed with radio frequency input power increases to evaluate the thermal stability of the F-SAW device in air and water environments. We demonstrate that the maximum temperature increase of the F-SAW device in the water was 1/20 of that in the air, owing to the very high convective heat transfer coefficient of the water, resulting in prevention of the performance degradation of the focused acoustic wave device.

  17. Flow profiling of a surface acoustic wave nanopump

    OpenAIRE

    Guttenberg, Z.; Rathgeber, A.; Keller, S.; Rädler, J. O.; Wixforth, A.; Kostur, M.; Schindler, M.; Talkner, P.

    2004-01-01

    The flow profile in a capillary gap and the pumping efficiency of an acoustic micropump employing Surface Acoustic Waves is investigated both experimentally and theoretically. Such ultrasonic surface waves on a piezoelectric substrate strongly couple to a thin liquid layer and generate an internal streaming within the fluid. Such acoustic streaming can be used for controlled agitation during, e.g., microarray hybridization. We use fluorescence correlation spectroscopy and fluorescence microsc...

  18. A low frequency acoustic insulator by using the acoustic metasurface to a Helmholtz resonator

    Directory of Open Access Journals (Sweden)

    Xiang Zhao

    2017-06-01

    Full Text Available Acoustic metasurfaces (AMSs are able to manipulate wavefronts at an anomalous angle through a subwavelength layer. Their application provide a new way to control sound waves in addition to traditional materials. In this work, we introduced the AMS into the design of a Helmholtz resonator (HR and studied the acoustic transmission through the modified HR in a pipe with one branch. The variation of sound insulation capacity with the phase gradient of the AMS was studied, and the results show that the AMS can remarkably lower the frequency band of the sound insulation without increasing the size. Our investigation provides a new degree of freedom for acoustic control with a Helmholtz resonator, which is of great significance in acoustic metasurface theory and sound insulation design.

  19. Asymmetric acoustic transmission in multiple frequency bands

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hong-xiang, E-mail: jsdxshx@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Yuan, Shou-qi, E-mail: Shouqiy@ujs.edu.cn [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Zhang, Shu-yi [Laboratory of Modern Acoustics, Institute of Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-11-23

    We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices.

  20. Asymmetric acoustic transmission in multiple frequency bands

    International Nuclear Information System (INIS)

    Sun, Hong-xiang; Yuan, Shou-qi; Zhang, Shu-yi

    2015-01-01

    We report both experimentally and numerically that the multi-band device of the asymmetric acoustic transmission is realized by placing two periodic gratings with different periods on both sides of two brass plates immersed in water. The asymmetric acoustic transmission can exist in four frequency bands below 1500 kHz, which arises from the interaction between various diffractions from the two gratings and Lamb modes in the brass plates immersed in water. The results indicate that the device has the advantages of multiple band, broader bandwidth, and simpler structure. Our finding should have great potential applications in ultrasonic devices

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

    Directory of Open Access Journals (Sweden)

    Yuanyuan Li

    2014-01-01

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

  2. In Situ Acoustic Monitoring of Thermal Spray Process Using High-Frequency Impulse Measurements

    Science.gov (United States)

    Tillmann, Wolfgang; Walther, Frank; Luo, Weifeng; Haack, Matthias; Nellesen, Jens; Knyazeva, Marina

    2018-01-01

    In order to guarantee their protective function, thermal spray coatings must be free from cracks, which expose the substrate surface to, e.g., corrosive media. Cracks in thermal spray coatings are usually formed because of tensile residual stresses. Most commonly, the crack occurrence is determined after the thermal spraying process by examination of metallographic cross sections of the coating. Recent efforts focus on in situ monitoring of crack formation by means of acoustic emission analysis. However, the acoustic signals related to crack propagation can be absorbed by the noise of the thermal spraying process. In this work, a high-frequency impulse measurement technique was applied to separate different acoustic sources by visualizing the characteristic signal of crack formation via quasi-real-time Fourier analysis. The investigations were carried out on a twin wire arc spraying process, utilizing FeCrBSi as a coating material. The impact of the process parameters on the acoustic emission spectrum was studied. Acoustic emission analysis enables to obtain global and integral information on the formed cracks. The coating morphology and coating defects were inspected using light microscopy on metallographic cross sections. Additionally, the resulting crack patterns were imaged in 3D by means of x-ray microtomography.

  3. Frequency effect on p-nitrophenol degradation under conditions of strict acoustic and electric control

    Directory of Open Access Journals (Sweden)

    Chang-ping Zhu

    2011-03-01

    Full Text Available The process of decomposing p-nitrophenol (PNP with power ultrasound requires strict control of acoustic and electric conditions. In this study, the conditions, including acoustic power and acoustic intensity, but not ultrasonic frequency, were controlled strictly at constant levels. The absorbency and the COD concentrations of the samples were measured in order to show the variation of the sample concentration. The results show significant differences in the trend of the solution degradation rate as acoustic power increases after the PNP solution (with a concentration of 114 mg/L and a pH value of 5.4 is irradiated for 60 min with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1 130.0 kHz. The degradation rate of the solution increases with time and acoustic power (acoustic intensity. On the other hand, the degradation rate of the solution is distinctly dependent on frequency when the acoustic power and intensity are strictly controlled and maintained at constant levels. The degradation rate of the PNP solution declines with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1 130.0 kHz; the COD concentration, on the contrary, increase.

  4. Spider web-structured labyrinthine acoustic metamaterials for low-frequency sound control

    Science.gov (United States)

    Krushynska, A. O.; Bosia, F.; Miniaci, M.; Pugno, N. M.

    2017-10-01

    Attenuating low-frequency sound remains a challenge, despite many advances in this field. Recently-developed acoustic metamaterials are characterized by unusual wave manipulation abilities that make them ideal candidates for efficient subwavelength sound control. In particular, labyrinthine acoustic metamaterials exhibit extremely high wave reflectivity, conical dispersion, and multiple artificial resonant modes originating from the specifically-designed topological architectures. These features enable broadband sound attenuation, negative refraction, acoustic cloaking and other peculiar effects. However, hybrid and/or tunable metamaterial performance implying enhanced wave reflection and simultaneous presence of conical dispersion at desired frequencies has not been reported so far. In this paper, we propose a new type of labyrinthine acoustic metamaterials (LAMMs) with hybrid dispersion characteristics by exploiting spider web-structured configurations. The developed design approach consists in adding a square surrounding frame to sectorial circular-shaped labyrinthine channels described in previous publications (e.g. (11)). Despite its simplicity, this approach provides tunability in the metamaterial functionality, such as the activation/elimination of subwavelength band gaps and negative group-velocity modes by increasing/decreasing the edge cavity dimensions. Since these cavities can be treated as extensions of variable-width internal channels, it becomes possible to exploit geometrical features, such as channel width, to shift the band gap position and size to desired frequencies. Time transient simulations demonstrate the effectiveness of the proposed metastructures for wave manipulation in terms of transmission or reflection coefficients, amplitude attenuation and time delay at subwavelength frequencies. The obtained results can be important for practical applications of LAMMs such as lightweight acoustic barriers with enhanced broadband wave

  5. Spider web-structured labyrinthine acoustic metamaterials for low-frequency sound control

    International Nuclear Information System (INIS)

    Krushynska, A O; Bosia, F; Miniaci, M; Pugno, N M

    2017-01-01

    Attenuating low-frequency sound remains a challenge, despite many advances in this field. Recently-developed acoustic metamaterials are characterized by unusual wave manipulation abilities that make them ideal candidates for efficient subwavelength sound control. In particular, labyrinthine acoustic metamaterials exhibit extremely high wave reflectivity, conical dispersion, and multiple artificial resonant modes originating from the specifically-designed topological architectures. These features enable broadband sound attenuation, negative refraction, acoustic cloaking and other peculiar effects. However, hybrid and/or tunable metamaterial performance implying enhanced wave reflection and simultaneous presence of conical dispersion at desired frequencies has not been reported so far. In this paper, we propose a new type of labyrinthine acoustic metamaterials (LAMMs) with hybrid dispersion characteristics by exploiting spider web-structured configurations. The developed design approach consists in adding a square surrounding frame to sectorial circular-shaped labyrinthine channels described in previous publications (e.g. (11)). Despite its simplicity, this approach provides tunability in the metamaterial functionality, such as the activation/elimination of subwavelength band gaps and negative group-velocity modes by increasing/decreasing the edge cavity dimensions. Since these cavities can be treated as extensions of variable-width internal channels, it becomes possible to exploit geometrical features, such as channel width, to shift the band gap position and size to desired frequencies. Time transient simulations demonstrate the effectiveness of the proposed metastructures for wave manipulation in terms of transmission or reflection coefficients, amplitude attenuation and time delay at subwavelength frequencies. The obtained results can be important for practical applications of LAMMs such as lightweight acoustic barriers with enhanced broadband wave

  6. Surface-acoustic-wave (SAW) flow sensor

    Science.gov (United States)

    Joshi, Shrinivas G.

    1991-03-01

    The use of a surface-acoustic-wave (SAW) device to measure the rate of gas flow is described. A SAW oscillator heated to a suitable temperature above ambient is placed in the path of a flowing gas. Convective cooling caused by the gas flow results in a change in the oscillator frequency. A 73-MHz oscillator fabricated on 128 deg rotated Y-cut lithium niobate substrate and heated to 55 C above ambient shows a frequency variation greater than 142 kHz for flow-rate variation from 0 to 1000 cu cm/min. The output of the sensor can be calibrated to provide a measurement of volume flow rate, pressure differential across channel ports, or mass flow rate. High sensitivity, wide dynamic range, and direct digital output are among the attractive features of this sensor. Theoretical expressions for the sensitivity and response time of the sensor are derived. It is shown that by using ultrasonic Lamb waves propagating in thin membranes, a flow sensor with faster response than a SAW sensor can be realized.

  7. Simultaneous measurement of surface tension and viscosity using freely decaying oscillations of acoustically levitated droplets

    Science.gov (United States)

    Kremer, J.; Kilzer, A.; Petermann, M.

    2018-01-01

    Oscillations of small liquid drops around a spherical shape have been of great interest to scientists measuring physical properties such as interfacial tension and viscosity, over the last few decades. A powerful tool for contactless positioning is acoustic levitation, which has been used to simultaneously determine the surface tension and viscosity of liquids at ambient pressure. In order to extend this acoustic levitation measurement method to high pressure systems, the method is first evaluated under ambient pressure. To measure surface tension and viscosity using acoustically levitated oscillating drops, an image analysis method has to be developed and factors which may affect measurement, such as sound field or oscillation amplitude, have to be analyzed. In this paper, we describe the simultaneous measurement of surface tension and viscosity using freely decaying shape oscillations of acoustically levitated droplets of different liquids (silicone oils AK 5 and AK 10, squalane, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol) in air. These liquids vary in viscosity from 2 to about 30 mPa s. An acoustic levitation system, including an optimized standing wave acoustic levitator and a high-speed camera, was used for this study. An image analysis was performed with a self-written Matlab® code. The frequency of oscillation and the damping constant, required for the determination of surface tension and viscosity, respectively, were calculated from the evolution of the equatorial and polar radii. The results and observations are compared to data from the literature in order to analyze the accuracy of surface tension and viscosity determination, as well as the effect of non-spherical drop shape or amplitude of oscillation on measurement.

  8. Frequency Shift of a Rotating Mass-Imbalance Immersed in an Acoustic Fluid

    International Nuclear Information System (INIS)

    Stephen R. Novascone; David M. Weinberg; Michael J. Anderson

    2005-01-01

    In this paper, we describe a physical mechanism that relates a measurable behavior of a vibrating device to the physical properties of a surrounding acoustic medium. The vibrating device under consideration is a rotating imbalance immersed in an unbounded acoustic fluid. It is assumed that the rotating imbalance is driven by an electromagnetic motor excited by a given DC voltage. If nonlinearities are ignored, the steady state operational frequency of such a device is determined by a balance between the applied electromagnetic and opposing frictional torque on the rotating imbalance. If nonlinearities are retained, it is shown that under certain circumstances, the surrounding acoustic medium exerts an additional time-averaged opposing torque on the rotating imbalance that reduces the operational frequency of the device. Consequently, the operational frequency of the device becomes linked to the physical properties of the surrounding medium. Analytical calculations showed that the radiative resistance of an acoustic fluid caused the opposing torque. The shift in frequency is proportional to the radiative resistance and the square of the rotating eccentricity, but inversely proportional the total transducer mass and the damping effect of the DC motor

  9. Frequency domain finite-element and spectral-element acoustic wave modeling using absorbing boundaries and perfectly matched layer

    Science.gov (United States)

    Rahimi Dalkhani, Amin; Javaherian, Abdolrahim; Mahdavi Basir, Hadi

    2018-04-01

    Wave propagation modeling as a vital tool in seismology can be done via several different numerical methods among them are finite-difference, finite-element, and spectral-element methods (FDM, FEM and SEM). Some advanced applications in seismic exploration benefit the frequency domain modeling. Regarding flexibility in complex geological models and dealing with the free surface boundary condition, we studied the frequency domain acoustic wave equation using FEM and SEM. The results demonstrated that the frequency domain FEM and SEM have a good accuracy and numerical efficiency with the second order interpolation polynomials. Furthermore, we developed the second order Clayton and Engquist absorbing boundary condition (CE-ABC2) and compared it with the perfectly matched layer (PML) for the frequency domain FEM and SEM. In spite of PML method, CE-ABC2 does not add any additional computational cost to the modeling except assembling boundary matrices. As a result, considering CE-ABC2 is more efficient than PML for the frequency domain acoustic wave propagation modeling especially when computational cost is high and high-level absorbing performance is unnecessary.

  10. Impact of acoustic airflow on intrasinus drug deposition: New insights into the vibrating mode and the optimal acoustic frequency to enhance the delivery of nebulized antibiotic.

    Science.gov (United States)

    Leclerc, Lara; Merhie, Amira El; Navarro, Laurent; Prévôt, Nathalie; Durand, Marc; Pourchez, Jérémie

    2015-10-15

    We investigated the impact of vibrating acoustic airflow, the high frequency (f≥100 Hz) and the low frequency (f≤45 Hz) sound waves, on the enhancement of intrasinus drug deposition. (81m)Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2-fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses, respectively. We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Flexible structured high-frequency film bulk acoustic resonator for flexible wireless electronics

    International Nuclear Information System (INIS)

    Zhou, Changjian; Shu, Yi; Yang, Yi; Ren, Tian-Ling; Jin, Hao; Dong, Shu-Rong; Chan, Mansun

    2015-01-01

    Flexible electronics have inspired many novel and very important applications in recent years and various flexible electronic devices such as diodes, transistors, circuits, sensors, and radiofrequency (RF) passive devices including antennas and inductors have been reported. However, the lack of a high-performance RF resonator is one of the key bottlenecks to implement flexible wireless electronics. In this study, for the first time, a novel ultra-flexible structured film bulk acoustic resonator (FBAR) is proposed. The flexible FBAR is fabricated on a flexible polyimide substrate using piezoelectric thin film aluminum nitride (AlN) for acoustic wave excitation. Both the shear wave and longitudinal wave can be excited under the surface interdigital electrodes configuration we proposed. In the case of the thickness extension mode, a flexible resonator with a working frequency as high as of 5.2325 GHz has been realized. The resonators stay fully functional under bending status and after repeated bending and re-flattening operations. This flexible high-frequency resonator will serve as a key building block for the future flexible wireless electronics, greatly expanding the application scope of flexible electronics. (paper)

  12. Observation of frequency cutoff for self-excited dust acoustic waves

    Science.gov (United States)

    Nosenko, V.; Zhdanov, S. K.; Morfill, G. E.; Kim, S.-H.; Heinrich, J.; Merlino, R. L.

    2009-11-01

    Complex (dusty) plasmas consist of fine solid particles suspended in a weakly ionized gas. Complex plasmas are excellent model systems to study wave phenomena down to the level of individual ``atoms''. Spontaneously excited dust acoustic waves were observed with high temporal resolution in a suspension of micron-size kaolin particles in a dc discharge in argon. Wave activity was found at frequencies as high as 400 Hz. At high wave numbers, the wave dispersion relation was acoustic-like (frequency proportional to wave number). At low wave numbers, the wave frequency did not tend to zero, but reached a cutoff frequency fc instead. The value of fc declined with distance from the anode. We propose a simple model that explains the observed cutoff by particle confinement in plasma. The existence of a cutoff frequency is very important for the propagation of waves: the waves excited above fc are propagating, and those below fc are evanescent.

  13. Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces.

    Science.gov (United States)

    Clare, Elizabeth L; Holderied, Marc W

    2015-09-01

    Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an 'acoustic shadow' cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for 'acoustic camouflage' as an anti-predator defence mechanism.

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

    International Nuclear Information System (INIS)

    Ishikawa, Isao; Suzuki, Yoshiaki; Ogura, Yukio; Katakura, Kageyoshi

    1997-01-01

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

  15. Simultaneous masking between electric and acoustic stimulation in cochlear implant users with residual low-frequency hearing.

    Science.gov (United States)

    Krüger, Benjamin; Büchner, Andreas; Nogueira, Waldo

    2017-09-01

    Ipsilateral electric-acoustic stimulation (EAS) is becoming increasingly important in cochlear implant (CI) treatment. Improvements in electrode designs and surgical techniques have contributed to improved hearing preservation during implantation. Consequently, CI implantation criteria have been expanded toward people with significant residual low-frequency hearing, who may benefit from the combined use of both the electric and acoustic stimulation in the same ear. However, only few studies have investigated the mutual interaction between electric and acoustic stimulation modalities. This work characterizes the interaction between both stimulation modalities using psychophysical masking experiments and cone beam computer tomography (CBCT). Two psychophysical experiments for electric and acoustic masking were performed to measure the hearing threshold elevation of a probe stimulus in the presence of a masker stimulus. For electric masking, the probe stimulus was an acoustic tone while the masker stimulus was an electric pulse train. For acoustic masking, the probe stimulus was an electric pulse train and the masker stimulus was an acoustic tone. Five EAS users, implanted with a CI and ipsilateral residual low-frequency hearing, participated in the study. Masking was determined at different electrodes and different acoustic frequencies. CBCT scans were used to determine the individual place-pitch frequencies of the intracochlear electrode contacts by using the Stakhovskaya place-to-frequency transformation. This allows the characterization of masking as a function of the difference between electric and acoustic stimulation sites, which we term the electric-acoustic frequency difference (EAFD). The results demonstrate a significant elevation of detection thresholds for both experiments. In electric masking, acoustic-tone thresholds increased exponentially with decreasing EAFD. In contrast, for the acoustic masking experiment, threshold elevations were present

  16. Dielectric and acoustical high frequency characterisation of PZT thin films

    International Nuclear Information System (INIS)

    Conde, Janine; Muralt, Paul

    2010-01-01

    Pb(Zr, Ti)O 3 (PZT) is an interesting material for bulk acoustic wave resonator applications due to its high electromechanical coupling constant, which would enable fabrication of large bandwidth frequency filters. The major challenge of the PZT solid solution system is to overcome mechanical losses generally observed in PZT ceramics. To increase the understanding of these losses in textured thin films, thin film bulk acoustic resonators (TFBAR's) based on PZT thin films with compositions either in the tetragonal region or at the morphotropic phase boundary and (111) or {100} textures were fabricated and studied up to 2 GHz. The dielectric and elastic materials coefficients were extracted from impedance measurements at the resonance frequency. The dispersion of the dielectric constant was obtained from impedance measurements up to 2 GHz. The films with varying compositions, textures and deposition methods (sol-gel or sputtering) were compared in terms of dielectric and acoustical properties.

  17. Dielectric and acoustical high frequency characterisation of PZT thin films

    Science.gov (United States)

    Conde, Janine; Muralt, Paul

    2010-02-01

    Pb(Zr, Ti)O3 (PZT) is an interesting material for bulk acoustic wave resonator applications due to its high electromechanical coupling constant, which would enable fabrication of large bandwidth frequency filters. The major challenge of the PZT solid solution system is to overcome mechanical losses generally observed in PZT ceramics. To increase the understanding of these losses in textured thin films, thin film bulk acoustic resonators (TFBAR's) based on PZT thin films with compositions either in the tetragonal region or at the morphotropic phase boundary and (111) or {100} textures were fabricated and studied up to 2 GHz. The dielectric and elastic materials coefficients were extracted from impedance measurements at the resonance frequency. The dispersion of the dielectric constant was obtained from impedance measurements up to 2 GHz. The films with varying compositions, textures and deposition methods (sol-gel or sputtering) were compared in terms of dielectric and acoustical properties.

  18. Surface Acoustic Wave (SAW for Chemical Sensing Applications of Recognition Layers

    Directory of Open Access Journals (Sweden)

    Adnan Mujahid

    2017-11-01

    Full Text Available Surface acoustic wave (SAW resonators represent some of the most prominent acoustic devices for chemical sensing applications. As their frequency ranges from several hundred MHz to GHz, therefore they can record remarkably diminutive frequency shifts resulting from exceptionally small mass loadings. Their miniaturized design, high thermal stability and possibility of wireless integration make these devices highly competitive. Owing to these special characteristics, they are widely accepted as smart transducers that can be combined with a variety of recognition layers based on host-guest interactions, metal oxide coatings, carbon nanotubes, graphene sheets, functional polymers and biological receptors. As a result of this, there is a broad spectrum of SAW sensors, i.e., having sensing applications ranging from small gas molecules to large bio-analytes or even whole cell structures. This review shall cover from the fundamentals to modern design developments in SAW devices with respect to interfacial receptor coatings for exemplary sensor applications. The related problems and their possible solutions shall also be covered, with a focus on emerging trends and future opportunities for making SAW as established sensing technology.

  19. Surface Acoustic Wave (SAW) for Chemical Sensing Applications of Recognition Layers.

    Science.gov (United States)

    Mujahid, Adnan; Dickert, Franz L

    2017-11-24

    Surface acoustic wave (SAW) resonators represent some of the most prominent acoustic devices for chemical sensing applications. As their frequency ranges from several hundred MHz to GHz, therefore they can record remarkably diminutive frequency shifts resulting from exceptionally small mass loadings. Their miniaturized design, high thermal stability and possibility of wireless integration make these devices highly competitive. Owing to these special characteristics, they are widely accepted as smart transducers that can be combined with a variety of recognition layers based on host-guest interactions, metal oxide coatings, carbon nanotubes, graphene sheets, functional polymers and biological receptors. As a result of this, there is a broad spectrum of SAW sensors, i.e., having sensing applications ranging from small gas molecules to large bio-analytes or even whole cell structures. This review shall cover from the fundamentals to modern design developments in SAW devices with respect to interfacial receptor coatings for exemplary sensor applications. The related problems and their possible solutions shall also be covered, with a focus on emerging trends and future opportunities for making SAW as established sensing technology.

  20. A high-performance lab-on-a-chip liquid sensor employing surface acoustic wave resonance

    Science.gov (United States)

    Kustanovich, K.; Yantchev, V.; Kirejev, V.; Jeffries, G. D. M.; Lobovkina, T.; Jesorka, A.

    2017-11-01

    We demonstrate herein a new concept for lab-on-a-chip in-liquid sensing, through integration of surface acoustic wave resonance (SAR) in a one-port configuration with a soft polymer microfluidic delivery system. In this concept, the reflective gratings of a one-port surface acoustic wave (SAW) resonator are employed as mass loading-sensing elements, while the SAW transducer is protected from the measurement environment. We describe the design, fabrication, implementation, and characterization using liquid medium. The sensor operates at a frequency of 185 MHz and has demonstrated a comparable sensitivity to other SAW in-liquid sensors, while offering quality factor (Q) value in water of about 250, low impedance and fairly low susceptibility to viscous damping. For proof of principle, sensing performance was evaluated by means of binding 40 nm neutravidin-coated SiO2 nanoparticles to a biotin-labeled lipid bilayer deposited over the reflectors. Frequency shifts were determined for every step of the affinity assay. Demonstration of this integrated technology highlights the potential of SAR technology for in-liquid sensing.

  1. Challenges and regulatory considerations in the acoustic measurement of high-frequency (>20 MHz) ultrasound.

    Science.gov (United States)

    Nagle, Samuel M; Sundar, Guru; Schafer, Mark E; Harris, Gerald R; Vaezy, Shahram; Gessert, James M; Howard, Samuel M; Moore, Mary K; Eaton, Richard M

    2013-11-01

    This article examines the challenges associated with making acoustic output measurements at high ultrasound frequencies (>20 MHz) in the context of regulatory considerations contained in the US Food and Drug Administration industry guidance document for diagnostic ultrasound devices. Error sources in the acoustic measurement, including hydrophone calibration and spatial averaging, nonlinear distortion, and mechanical alignment, are evaluated, and the limitations of currently available acoustic measurement instruments are discussed. An uncertainty analysis of acoustic intensity and power measurements is presented, and an example uncertainty calculation is done on a hypothetical 30-MHz high-frequency ultrasound system. This analysis concludes that the estimated measurement uncertainty of the acoustic intensity is +73%/-86%, and the uncertainty in the mechanical index is +37%/-43%. These values exceed the respective levels in the Food and Drug Administration guidance document of 30% and 15%, respectively, which are more representative of the measurement uncertainty associated with characterizing lower-frequency ultrasound systems. Recommendations made for minimizing the measurement uncertainty include implementing a mechanical positioning system that has sufficient repeatability and precision, reconstructing the time-pressure waveform via deconvolution using the hydrophone frequency response, and correcting for hydrophone spatial averaging.

  2. Low-Frequency Acoustic Noise Mitigation Characteristics of Metamaterials-Inspired Vibro-Impact Structures

    Science.gov (United States)

    Rekhy, Anuj

    Acoustic absorbers like foams, fiberglass or liners have been used commonly in structures for infrastructural, industrial, automotive and aerospace applications to mitigate noise. However, these conventional materials have limited effectiveness to mitigate low-frequency (LF) acoustic waves with frequency less than 400 Hz owing to the need for impractically large mass or volume. LF acoustic waves contribute significantly towards environmental noise pollution as well as unwanted structural responses. Therefore, there is a need to develop lightweight, compact, structurally-integrated solutions to mitigate LF noise in several applications. Inspired by metamaterials, which are man-made structural materials that derive their unique dynamic behavior not just from material constituents but more so from engineered configurations, tuned mass-loaded membranes as vibro-impact attachments on a baseline structure are investigated to determine their performance as a LF acoustic barrier. The hypothesis is that the LF incident waves are up-converted via impact to higher modes in the baseline structure which are far more evanescent and may then be effectively mitigated using conventional means. Such Metamaterials-Inspired Vibro-Impact Structures (MIVIS) could be tuned to match the dominant frequency content of LF acoustic sources in specific applications. Prototype MIVIS unit cells were designed and tested to study the energy transfer mechanism via impact-induced frequency up-conversion, and the consequent sound transmission loss. Structural acoustic simulations were done to predict responses using models based on normal incidence transmission loss tests. Experimental proof-of-concept was achieved and further correlations to simulations were utilized to optimize the energy up-conversion mechanism using parametric studies. Up to 36 dB of sound transmission loss increase is obtained at the anti-resonance frequency (326 Hz) within a tunable LF bandwidth of about 200 Hz while impact

  3. Dielectric and acoustical high frequency characterisation of PZT thin films

    Energy Technology Data Exchange (ETDEWEB)

    Conde, Janine; Muralt, Paul, E-mail: janine.conde@epfl.ch [Department of Materials Science, EPFL (Switzerland)

    2010-02-15

    Pb(Zr, Ti)O{sub 3} (PZT) is an interesting material for bulk acoustic wave resonator applications due to its high electromechanical coupling constant, which would enable fabrication of large bandwidth frequency filters. The major challenge of the PZT solid solution system is to overcome mechanical losses generally observed in PZT ceramics. To increase the understanding of these losses in textured thin films, thin film bulk acoustic resonators (TFBAR's) based on PZT thin films with compositions either in the tetragonal region or at the morphotropic phase boundary and (111) or {l_brace}100{r_brace} textures were fabricated and studied up to 2 GHz. The dielectric and elastic materials coefficients were extracted from impedance measurements at the resonance frequency. The dispersion of the dielectric constant was obtained from impedance measurements up to 2 GHz. The films with varying compositions, textures and deposition methods (sol-gel or sputtering) were compared in terms of dielectric and acoustical properties.

  4. Study of non-spherical bubble oscillations near a surface in a weak acoustic standing wave field.

    Science.gov (United States)

    Xi, Xiaoyu; Cegla, Frederic; Mettin, Robert; Holsteyns, Frank; Lippert, Alexander

    2014-04-01

    The interaction of acoustically driven bubbles with a wall is important in many applications of ultrasound and cavitation, as the close boundary can severely alter the bubble dynamics. In this paper, the non-spherical surface oscillations of bubbles near a surface in a weak acoustic standing wave field are investigated experimentally and numerically. The translation, the volume, and surface mode oscillations of bubbles near a flat glass surface were observed by a high speed camera in a standing wave cell at 46.8 kHz. The model approach is based on a modified Keller-Miksis equation coupled to surface mode amplitude equations in the first order, and to the translation equations. Modifications are introduced due to the adjacent wall. It was found that a bubble's oscillation mode can change in the presence of the wall, as compared to the bubble in the bulk liquid. In particular, the wall shifts the instability pressure thresholds to smaller driving frequencies for fixed bubble equilibrium radii, or to smaller equilibrium radii for fixed excitation frequency. This can destabilize otherwise spherical bubbles, or stabilize bubbles undergoing surface oscillations in the bulk. The bubble dynamics observed in experiment demonstrated the same trend as the theoretical results.

  5. Surface acoustic wave micromotor with arbitrary axis rotational capability

    Science.gov (United States)

    Tjeung, Ricky T.; Hughes, Mark S.; Yeo, Leslie Y.; Friend, James R.

    2011-11-01

    A surface acoustic wave (SAW) actuated rotary motor is reported here, consisting of a millimeter-sized spherical metal rotor placed on the surface of a lead zirconate titanate piezoelectric substrate upon which the SAW is made to propagate. At the design frequency of 3.2 MHz and with a fixed preload of 41.1 μN, the maximum rotational speed and torque achieved were approximately 1900 rpm and 5.37 μN-mm, respectively, producing a maximum output power of 1.19 μW. The surface vibrations were visualized using laser Doppler vibrometry and indicate that the rotational motion arises due to retrograde elliptical motions of the piezoelectric surface elements. Rotation about orthogonal axes in the plane of the substrate has been obtained by using orthogonally placed interdigital electrodes on the substrate to generate SAW impinging on the rotor, offering a means to generate rotation about an arbitrary axis in the plane of the substrate.

  6. AlScN thin film based surface acoustic wave devices with enhanced microfluidic performance

    International Nuclear Information System (INIS)

    Wang, W B; Xuan, W P; Chen, J K; Wang, X Z; Luo, J K; Fu, Y Q; Chen, J J; Duan, P F; Mayrhofer, P; Bittner, A; Schmid, U

    2016-01-01

    This paper reports the characterization of scandium aluminum nitride (Al 1−xS c xN , x   =  27%) films and discusses surface acoustic wave (SAW) devices based on them. Both AlScN and AlN films were deposited on silicon by sputtering and possessed columnar microstructures with (0 0 0 2) crystal orientation. The AlScN/Si SAW devices showed improved electromechanical coupling coefficients ( K 2 , ∼2%) compared with pure AlN films (<0.5%). The performance of the two types of devices was also investigated and compared, using acoustofluidics as an example. The AlScN/Si SAW devices achieved much lower threshold powers for the acoustic streaming and pumping of liquid droplets, and the acoustic streaming and pumping velocities were 2  ×  and 3  ×  those of the AlN/Si SAW devices, respectively. Mechanical characterization showed that the Young’s modulus and hardness of the AlN film decreased significantly when Sc was doped, and this was responsible for the decreased acoustic velocity and resonant frequency, and the increased temperature coefficient of frequency, of the AlScN SAW devices. (paper)

  7. Infrared beam-steering using acoustically modulated surface plasmons over a graphene monolayer

    KAUST Repository

    Chen, Paiyen

    2014-09-01

    We model and design a graphene-based infrared beamformer based on the concept of leaky-wave (fast traveling wave) antennas. The excitation of infrared surface plasmon polaritons (SPPs) over a \\'one-atom-thick\\' graphene monolayer is typically associated with intrinsically \\'slow light\\'. By modulating the graphene with elastic vibrations based on flexural waves, a dynamic diffraction grating can be formed on the graphene surface, converting propagating SPPs into fast surface waves, able to radiate directive infrared beams into the background medium. This scheme allows fast on-off switching of infrared emission and dynamic tuning of its radiation pattern, beam angle and frequency of operation, by simply varying the acoustic frequency that controls the effective grating period. We envision that this graphene beamformer may be integrated into reconfigurable transmitter/receiver modules, switches and detectors for THz and infrared wireless communication, sensing, imaging and actuation systems.

  8. High-Temperature Surface-Acoustic-Wave Transducer

    Science.gov (United States)

    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.

  9. Acoustic properties of a porous glass (vycor) at hypersonic frequencies

    International Nuclear Information System (INIS)

    Levelut, C; Pelous, J

    2007-01-01

    Brillouin scattering experiments have been performed from 5 to 1600 K in vycor, a porous silica glass. The acoustic velocity and attenuation at hypersonic frequencies are compared to those of bulk silica and others porous silica samples. The experimental evidence for the influence of porosity on the scattering by acoustic waves is compared to calculations. The correlation between internal friction and thermal conductivity at low temperature is discussed

  10. Frequency Domain Multi-parameter Full Waveform Inversion for Acoustic VTI Media

    KAUST Repository

    Djebbi, Ramzi

    2017-05-26

    Multi-parameter full waveform inversion (FWI) for transversely isotropic (TI) media with vertical axis of symmetry (VTI) suffers from the trade-off between the parameters. The trade-off results in the leakage of one parameter\\'s update into the other during the inversion. It affects the accuracy and convergence of the inversion. The sensitivity analyses suggested a parameterisation using the horizontal velocity vh, epsilon and eta to reduce the trade-off for surface recorded seismic data.We test the (vh, epsilon, eta) parameterisation for acoustic VTI media using a scattering integral (SI) based inversion. The data is modeled in frequency domain and the model is updated using a preconditioned conjugate gradient method. We applied the method to the VTI Marmousi II model and in the inversion, we keep eta parameter fixed as the background initial model and we invert simultaneously for both vh and epsilon. The results show the suitability of the parameterisation for multi-parameter VTI acoustic inversion as well as the accuracy of the inversion approach.

  11. Acoustic detection of pneumothorax

    Science.gov (United States)

    Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.

    2003-04-01

    This study aims at investigating the feasibility of using low-frequency (pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (ppneumothorax states (pPneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (pPneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.

  12. Particle separation by phase modulated surface acoustic waves.

    Science.gov (United States)

    Simon, Gergely; Andrade, Marco A B; Reboud, Julien; Marques-Hueso, Jose; Desmulliez, Marc P Y; Cooper, Jonathan M; Riehle, Mathis O; Bernassau, Anne L

    2017-09-01

    High efficiency isolation of cells or particles from a heterogeneous mixture is a critical processing step in lab-on-a-chip devices. Acoustic techniques offer contactless and label-free manipulation, preserve viability of biological cells, and provide versatility as the applied electrical signal can be adapted to various scenarios. Conventional acoustic separation methods use time-of-flight and achieve separation up to distances of quarter wavelength with limited separation power due to slow gradients in the force. The method proposed here allows separation by half of the wavelength and can be extended by repeating the modulation pattern and can ensure maximum force acting on the particles. In this work, we propose an optimised phase modulation scheme for particle separation in a surface acoustic wave microfluidic device. An expression for the acoustic radiation force arising from the interaction between acoustic waves in the fluid was derived. We demonstrated, for the first time, that the expression of the acoustic radiation force differs in surface acoustic wave and bulk devices, due to the presence of a geometric scaling factor. Two phase modulation schemes are investigated theoretically and experimentally. Theoretical findings were experimentally validated for different mixtures of polystyrene particles confirming that the method offers high selectivity. A Monte-Carlo simulation enabled us to assess performance in real situations, including the effects of particle size variation and non-uniform acoustic field on sorting efficiency and purity, validating the ability to separate particles with high purity and high resolution.

  13. Modulation of cavity-polaritons by surface acoustic waves

    DEFF Research Database (Denmark)

    de Lima, M. M.; Poel, Mike van der; Hey, R.

    2006-01-01

    We modulate cavity-polaritons using surface acoustic waves. The corresponding formation of a mini-Brillouin zone and band folding of the polariton dispersion is demonstrated for the first time. Results are in good agreement with model calculations.......We modulate cavity-polaritons using surface acoustic waves. The corresponding formation of a mini-Brillouin zone and band folding of the polariton dispersion is demonstrated for the first time. Results are in good agreement with model calculations....

  14. Surface Acoustic Wave Devices for Harsh Environment Wireless Sensing

    Directory of Open Access Journals (Sweden)

    David W. Greve

    2013-05-01

    Full Text Available 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.

  15. Analytical and numerical calculations of optimum design frequency for focused ultrasound therapy and acoustic radiation force.

    Science.gov (United States)

    Ergün, A Sanlı

    2011-10-01

    Focused ultrasound therapy relies on acoustic power absorption by tissue. The stronger the absorption the higher the temperature increase is. However, strong acoustic absorption also means faster attenuation and limited penetration depth. Hence, there is a trade-off between heat generation efficacy and penetration depth. In this paper, we formulated the acoustic power absorption as a function of frequency and attenuation coefficient, and defined two figures of merit to measure the power absorption: spatial peak of the acoustic power absorption density, and the acoustic power absorbed within the focal area. Then, we derived "rule of thumb" expressions for the optimum frequencies that maximized these figures of merit given the target depth and homogeneous tissue type. We also formulated a method to calculate the optimum frequency for inhomogeneous tissue given the tissue composition for situations where the tissue structure can be assumed to be made of parallel layers of homogeneous tissue. We checked the validity of the rules using linear acoustic field simulations. For a one-dimensional array of 4cm acoustic aperture, and for a two-dimensional array of 4×4cm(2) acoustic aperture, we found that the power absorbed within the focal area is maximized at 0.86MHz, and 0.79MHz, respectively, when the target depth is 4cm in muscle tissue. The rules on the other hand predicted the optimum frequencies for acoustic power absorption as 0.9MHz and 0.86MHz, respectively for the 1D and 2D array case, which are within 6% and 9% of the field simulation results. Because radiation force generated by an acoustic wave in a lossy propagation medium is approximately proportional to the acoustic power absorption, these rules can be used to maximize acoustic radiation force generated in tissue as well. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Flow profiling of a surface-acoustic-wave nanopump

    Science.gov (United States)

    Guttenberg, Z.; Rathgeber, A.; Keller, S.; Rädler, J. O.; Wixforth, A.; Kostur, M.; Schindler, M.; Talkner, P.

    2004-11-01

    The flow profile in a capillary gap and the pumping efficiency of an acoustic micropump employing surface acoustic waves is investigated both experimentally and theoretically. Ultrasonic surface waves on a piezoelectric substrate strongly couple to a thin liquid layer and generate a quadrupolar streaming pattern within the fluid. We use fluorescence correlation spectroscopy and fluorescence microscopy as complementary tools to investigate the resulting flow profile. The velocity was found to depend on the applied power approximately linearly and to decrease with the inverse third power of the distance from the ultrasound generator on the chip. The found properties reveal acoustic streaming as a promising tool for the controlled agitation during microarray hybridization.

  17. Shallow Water Acoustic Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Supports experimental research where high-frequency acoustic scattering and surface vibration measurements of fluid-loaded and non-fluid-loaded structures...

  18. Extreme Low Frequency Acoustic Measurement System

    Science.gov (United States)

    Shams, Qamar A. (Inventor); Zuckerwar, Allan J. (Inventor)

    2017-01-01

    The present invention is an extremely low frequency (ELF) microphone and acoustic measurement system capable of infrasound detection in a portable and easily deployable form factor. In one embodiment of the invention, an extremely low frequency electret microphone comprises a membrane, a backplate, and a backchamber. The backchamber is sealed to allow substantially no air exchange between the backchamber and outside the microphone. Compliance of the membrane may be less than ambient air compliance. The backplate may define a plurality of holes and a slot may be defined between an outer diameter of the backplate and an inner wall of the microphone. The locations and sizes of the holes, the size of the slot, and the volume of the backchamber may be selected such that membrane motion is substantially critically damped.

  19. Acoustic signal analysis in the creeping discharge

    International Nuclear Information System (INIS)

    Nakamiya, T; Sonoda, Y; Tsuda, R; Ebihara, K; Ikegami, T

    2008-01-01

    We have previously succeeded in measuring the acoustic signal due to the dielectric barrier discharge and discriminating the dominant frequency components of the acoustic signal. The dominant frequency components appear over 20kHz of acoustic signal by the dielectric barrier discharge. Recently surface discharge control technology has been focused from practical applications such as ozonizer, NO X reactors, light source or display. The fundamental experiments are carried to examine the creeping discharge using the acoustic signal. When the high voltage (6kV, f = 10kHz) is applied to the electrode, the discharge current flows and the acoustic sound is generated. The current, voltage waveforms of creeping discharge and the sound signal detected by the condenser microphone are stored in the digital memory scope. In this scheme, Continuous Wavelet Transform (CWT) is applied to discriminate the acoustic sound of the micro discharge and the dominant frequency components are studied. CWT results of sound signal show the frequency spectrum of wideband up to 100kHz. In addition, the energy distributions of acoustic signal are examined by CWT

  20. Nondestructive testing of thin films using surface acoustic waves and laser ultrasonics

    Science.gov (United States)

    Jenot, Frédéric; Fourez, Sabrina; Ouaftouh, Mohammadi; Duquennoy, Marc

    2018-04-01

    Thin films are widely used in many fields such as electronics, optics or materials science. For example, they find applications in thermal or mechanical sensors design. They are also very useful as protective or reinforcement layers for many structures. However, some coating defects such as thickness variations, microfissuring or poor adhesion are common problems. Therefore, nondestructive testing of these structures using acoustic waves generated and detected by lasers represents a major interest. Indeed, in comparison with conventional methods based on the use of piezoelectric transducers, laser ultrasonics leads to non-contact investigations with a large bandwidth. Usually, bulk acoustic waves are used and a pulse-echo technique is considered that needs high frequencies and implies local measurements. In order to avoid this limitation, we propose to use surface acoustic waves in a frequency range up to 45 MHz. The samples consist of a micrometric gold layer deposited on silicon substrates. In a first part, using dispersion analysis, theoretical and experimental results clearly reveal that the first Rayleigh mode allows the detection of film thickness variations and open cracks. In a second part, a localized adhesion defect is introduced in a similar sample. The effects of such a flaw on the Rayleigh modes dispersion curves are theoretically described. Finally, we experimentally show that the first Rayleigh mode allows the defect detection only under specific conditions.

  1. Active micromixer using surface acoustic wave streaming

    Science.gov (United States)

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

    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.

  2. Nonlinear generation of non-acoustic modes by low-frequency sound in a vibrationally relaxing gas

    International Nuclear Information System (INIS)

    Perelomova, A.

    2010-01-01

    Two dynamic equations referring to a weakly nonlinear and weakly dispersive flow of a gas in which molecular vibrational relaxation takes place, are derived. The first one governs an excess temperature associated with the thermal mode, and the second one describes variations in vibrational energy. Both quantities refer to non-wave types of gas motion. These variations are caused by the nonlinear transfer of acoustic energy into thermal mode and internal vibrational degrees of freedom of a relaxing gas. The final dynamic equations are instantaneous; they include a quadratic nonlinear acoustic source, reflecting the nonlinear character of interaction of low-frequency acoustic and non-acoustic motions of the fluid. All types of sound, periodic or aperiodic, may serve as an acoustic source of both phenomena. The low-frequency sound is considered in this study. Some conclusions about temporal behavior of non-acoustic modes caused by periodic and aperiodic sound are made. Under certain conditions, acoustic cooling takes place instead of heating. (author)

  3. Acoustic tweezers: patterning cells and microparticles using standing surface acoustic waves (SSAW).

    Science.gov (United States)

    Shi, Jinjie; Ahmed, Daniel; Mao, Xiaole; Lin, Sz-Chin Steven; Lawit, Aitan; Huang, Tony Jun

    2009-10-21

    Here we present an active patterning technique named "acoustic tweezers" that utilizes standing surface acoustic wave (SSAW) to manipulate and pattern cells and microparticles. This technique is capable of patterning cells and microparticles regardless of shape, size, charge or polarity. Its power intensity, approximately 5x10(5) times lower than that of optical tweezers, compares favorably with those of other active patterning methods. Flow cytometry studies have revealed it to be non-invasive. The aforementioned advantages, along with this technique's simple design and ability to be miniaturized, render the "acoustic tweezers" technique a promising tool for various applications in biology, chemistry, engineering, and materials science.

  4. Writing magnetic patterns with surface acoustic waves

    Energy Technology Data Exchange (ETDEWEB)

    Li, Weiyang; Buford, Benjamin; Jander, Albrecht; Dhagat, Pallavi, E-mail: dhagat@eecs.oregonstate.edu [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331 (United States)

    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.

  5. Radiation dominated acoustophoresis driven by surface acoustic waves.

    Science.gov (United States)

    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. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. A boundary integral equation method using auxiliary interior surface approach for acoustic radiation and scattering in two dimensions.

    Science.gov (United States)

    Yang, S A

    2002-10-01

    This paper presents an effective solution method for predicting acoustic radiation and scattering fields in two dimensions. The difficulty of the fictitious characteristic frequency is overcome by incorporating an auxiliary interior surface that satisfies certain boundary condition into the body surface. This process gives rise to a set of uniquely solvable boundary integral equations. Distributing monopoles with unknown strengths over the body and interior surfaces yields the simple source formulation. The modified boundary integral equations are further transformed to ordinary ones that contain nonsingular kernels only. This implementation allows direct application of standard quadrature formulas over the entire integration domain; that is, the collocation points are exactly the positions at which the integration points are located. Selecting the interior surface is an easy task. Moreover, only a few corresponding interior nodal points are sufficient for the computation. Numerical calculations consist of the acoustic radiation and scattering by acoustically hard elliptic and rectangular cylinders. Comparisons with analytical solutions are made. Numerical results demonstrate the efficiency and accuracy of the current solution method.

  7. Terahertz acoustic phonon detection from a compact surface layer of spherical nanoparticles powder mixture of aluminum, alumina and multi-walled carbon nanotube

    Science.gov (United States)

    Abouelsayed, A.; Ebrahim, M. R.; El hotaby, W.; Hassan, S. A.; Al-Ashkar, Emad

    2017-10-01

    We present terahertz spectroscopy study on spherical nanoparticles powder mixture of aluminum, alumina, and MWCNTs induced by surface mechanical attrition treatment (SMAT) of aluminum substrates. Surface alloying of AL, Al2O3 0.95% and MWCNTs 0.05% powder mixture was produced during SMAT process, where a compact surface layer of about 200 μm due to ball bombardment was produced from the mixture. Al2O3 alumina powder played a significant role in MWCNTs distribution on surface, those were held in deformation surface cites of micro-cavities due to SMAT process of Al. The benefits are the effects on resulted optical properties of the surface studied at the terahertz frequency range due to electrical isolation confinement effects and electronic resonance disturbances exerted on Al electronic resonance at the same range of frequencies. THz acoustic phonon around 0.53-0.6 THz (17-20 cm-1) were observed at ambient conditions for the spherical nanoparticles powder mixture of Al, Al2O3 and MWCNTs. These results suggested that the presence of Al2O3 and MWCNTs during SMAT process leads to the optically detection of such acoustic phonon in the THz frequency range.

  8. Surface acoustic waves in acoustic superlattice lithium niobate coated with a waveguide layer

    Science.gov (United States)

    Yang, G. Y.; Du, J. K.; Huang, B.; Jin, Y. A.; Xu, M. H.

    2017-04-01

    The effects of the waveguide layer on the band structure of Rayleigh waves are studied in this work based on a one-dimensional acoustic superlattice lithium niobate substrate coated with a waveguide layer. The present phononic structure is formed by the periodic domain-inverted single crystal that is the Z-cut lithium niobate substrate with a waveguide layer on the upper surface. The plane wave expansion method (PWE) is adopted to determine the band gap behavior of the phononic structure and validated by the finite element method (FEM). The FEM is also used to investigate the transmission of Rayleigh waves in the phononic structure with the interdigital transducers by means of the commercial package COMSOL. The results show that, although there is a homogeneous waveguide layer on the surface, the band gap of Rayleigh waves still exist. It is also found that increasing the thickness of the waveguide layer, the band width narrows and the band structure shifts to lower frequency. The present approach can be taken as an efficient tool in designing of phononic structures with waveguide layer.

  9. Surface acoustic waves in acoustic superlattice lithium niobate coated with a waveguide layer

    Directory of Open Access Journals (Sweden)

    G. Y. Yang

    2017-04-01

    Full Text Available The effects of the waveguide layer on the band structure of Rayleigh waves are studied in this work based on a one-dimensional acoustic superlattice lithium niobate substrate coated with a waveguide layer. The present phononic structure is formed by the periodic domain-inverted single crystal that is the Z-cut lithium niobate substrate with a waveguide layer on the upper surface. The plane wave expansion method (PWE is adopted to determine the band gap behavior of the phononic structure and validated by the finite element method (FEM. The FEM is also used to investigate the transmission of Rayleigh waves in the phononic structure with the interdigital transducers by means of the commercial package COMSOL. The results show that, although there is a homogeneous waveguide layer on the surface, the band gap of Rayleigh waves still exist. It is also found that increasing the thickness of the waveguide layer, the band width narrows and the band structure shifts to lower frequency. The present approach can be taken as an efficient tool in designing of phononic structures with waveguide layer.

  10. Frequency and Thermal Behavior of Acoustic Absorption in ɛ-GaSe Crystals

    Science.gov (United States)

    Dzhafarova, S. Z.

    2018-04-01

    The paper presents results of measuring acoustic absorption in ɛ-GaSe crystals. The absorption of a longitudinal wave which propagates normal to the crystal layers, quadratically depends on frequency. However, it does not depend on temperature, i.e. it displays an Akhiezer behavior although its absolute value considerably exceeds the expected. The analysis of the frequency and thermal behavior of absorption of piezoelectric waves propagating along the layers, includes the deduction of contribution made by the interaction between waves and charge carriers. This analysis shows the linear dependence between the lattice absorption of these waves and the frequency. The linear frequency and weak temperature dependences of the acoustic absorption characterize the additional ultra-Akhiezer absorption in glasses. In our case, it can be caused by various polytypes forming in GaSe crystals which differ merely in a mutual arrangement of layers.

  11. Enhancing the beamforming map of spherical arrays at low frequencies using acoustic holography

    DEFF Research Database (Denmark)

    Tiana Roig, Elisabet; Torras Rosell, Antoni; Fernandez Grande, Efren

    2014-01-01

    Recent studies have shown that the localization of acoustic sources based on circular arrays can be improved at low frequencies by combining beamforming with acoustic holography. This paper extends this technique to the three dimensional case by making use of spherical arrays. The pressure captur...

  12. Membrane-constrained acoustic metamaterials for low frequency sound insulation

    Science.gov (United States)

    Wang, Xiaole; Zhao, Hui; Luo, Xudong; Huang, Zhenyu

    2016-01-01

    We present a constrained membrane-type acoustic metamaterial (CMAM) that employs constraint sticks to add out-of-plane dimensions in the design space of MAM. A CMAM sample, which adopts constraint sticks to suppress vibrations at the membrane center, was fabricated to achieve a sound transmission loss (STL) peak of 26 dB at 140 Hz, with the static areal density of 6.0 kg/m2. The working mechanism of the CMAM as an acoustic metamaterial is elucidated by calculating the averaged normal displacement, the equivalent areal density, and the effective dynamic mass of a unit cell through finite element simulations. Furthermore, the vibration modes of the CMAM indicate that the eigenmodes related to STL dips are shifted into high frequencies, thus broadening its effective bandwidth significantly. Three samples possessing the same geometry and material but different constraint areas were fabricated to illustrate the tunability of STL peaks at low frequencies.

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

    Science.gov (United States)

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

    2016-02-09

    The ability of surface acoustic waves to trap and manipulate micrometer-scale particles and biological cells has led to many applications involving "acoustic tweezers" in biology, chemistry, engineering, and medicine. Here, we present 3D acoustic tweezers, which use surface acoustic waves to create 3D trapping nodes for the capture and manipulation of microparticles and cells along three mutually orthogonal axes. In this method, we use standing-wave phase shifts to move particles or cells in-plane, whereas the amplitude of acoustic vibrations is used to control particle motion along an orthogonal plane. We demonstrate, through controlled experiments guided by simulations, how acoustic vibrations result in micromanipulations in a microfluidic chamber by invoking physical principles that underlie the formation and regulation of complex, volumetric trapping nodes of particles and biological cells. We further show how 3D acoustic tweezers can be used to pick up, translate, and print single cells and cell assemblies to create 2D and 3D structures in a precise, noninvasive, label-free, and contact-free manner.

  14. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    Science.gov (United States)

    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.

  15. Acoustic tomography in the atmospheric surface layer

    Directory of Open Access Journals (Sweden)

    A. Ziemann

    Full Text Available Acoustic tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area-averaged values of meteorological parameters. As a result consistent data will be obtained for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of acoustic tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. Therefore, to provide a general overview of sound propagation under various atmospheric conditions a two-dimensional ray-tracing model according to a modified version of Snell's law is used. The state of the crossed atmosphere can be estimated from measurements of acoustic travel time between sources and receivers at different points. Derivation of area-averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all acoustic paths. Thereby, the applied straight ray two-dimensional tomographic model using SIRT (simultaneous iterative reconstruction technique is characterised as a method with small computational requirements, satisfactory convergence and stability properties as well as simple handling, especially, during online evaluation.

    Key words. Meteorology and atmospheric dynamics (turbulence; instruments and techniques.

  16. Picosecond ultrasonic study of surface acoustic waves on titanium nitride nanostructures

    International Nuclear Information System (INIS)

    Bjornsson, M. M.; Connolly, A. B.; Mahat, S.; Rachmilowitz, B. E.; Daly, B. C.; Antonelli, G. A.; Myers, A.; Singh, K. J.; Yoo, H. J.; King, S. W.

    2015-01-01

    We have measured surface acoustic waves on nanostructured TiN wires overlaid on multiple thin films on a silicon substrate using the ultrafast pump-probe technique known as picosecond ultrasonics. We find a prominent oscillation in the range of 11–54 GHz for samples with varying pitch ranging from 420 nm down to 168 nm. We find that the observed oscillation increases monotonically in frequency with decrease in pitch, but that the increase is not linear. By comparing our data to two-dimensional mechanical simulations of the nanostructures, we find that the type of surface oscillation to which we are sensitive changes depending on the pitch of the sample. Surface waves on substrates that are loaded by thin films can take multiple forms, including Rayleigh-like waves, Sezawa waves, and radiative (leaky) surface waves. We describe evidence for detection of modes that display characteristics of these three surface wave types

  17. Design and simulation study of high frequency response for surface acoustic wave device by using CST software

    Science.gov (United States)

    Zakaria, M. R.; Hashim, U.; Amin, Mohd Hasrul I. M.; Ayub, R. Mat; Hashim, M. N.; Adam, T.

    2015-05-01

    This paper focuses on the enhancement and improvement of the Surface Acoustic Wave (SAW) device performance. Due to increased demand in the international market for biosensor product, the product must be emphasized in terms of quality. However, within the technological advances, demand for device with low cost, high efficiency and friendly-user preferred. Surface Acoustic Wave (SAW) device with the combination of pair electrode know as Interdigital Transducer (IDT) was fabricated on a piezoelectric substrate. The design of Interdigital Transducer (IDT) parameter is changes in several sizes and values for which it is able to provide greater efficiency in sensing sensitivity by using process simulation with CST STUDIO Suite software. In addition, Interdigital Transducer (IDT) parameters also changed to be created the products with a smaller size and easy to handle where it also reduces the cost of this product. Parameter values of an Interdigital Transducer (IDT) will be changed in the design is the total number of fingers pair, finger length, finger width and spacing, aperture and also the thickness of the Interdigital Transducer (IDT). From the result, the performance of the sensor is improved significantly after modification is done.

  18. Passive wireless surface acoustic wave sensors for monitoring sequestration sites CO2 emission

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yizhong [Univ. of Pittsburgh, PA (United States); Chyu, Minking [Univ. of Pittsburgh, PA (United States); Wang, Qing-Ming [Univ. of Pittsburgh, PA (United States)

    2013-02-14

    University of Pittsburgh’s Transducer lab has teamed with the U.S. Department of Energy’s National Energy Technology Laboratory (DOE NETL) to conduct a comprehensive study to develop/evaluate low-cost, efficient CO2 measuring technologies for geological sequestration sites leakage monitoring. A passive wireless CO2 sensing system based on surface acoustic wave technology and carbon nanotube nanocomposite was developed. Surface acoustic wave device was studied to determine the optimum parameters. Delay line structure was adopted as basic sensor structure. CNT polymer nanocomposite was fabricated and tested under different temperature and strain condition for natural environment impact evaluation. Nanocomposite resistance increased for 5 times under pure strain, while the temperature dependence of resistance for CNT solely was -1375ppm/°C. The overall effect of temperature on nanocomposite resistance was -1000ppm/°C. The gas response of the nanocomposite was about 10% resistance increase under pure CO2 . The sensor frequency change was around 300ppm for pure CO2 . With paralyne packaging, the sensor frequency change from relative humidity of 0% to 100% at room temperature decreased from over 1000ppm to less than 100ppm. The lowest detection limit of the sensor is 1% gas concentration, with 36ppm frequency change. Wireless module was tested and showed over one foot transmission distance at preferred parallel orientation.

  19. Quantum Control of a Nitrogen-Vacancy Center using Surface Acoustic Waves in the Resolved Sideband Limit

    Science.gov (United States)

    Golter, David; Oo, Thein; Amezcua, Maira; Wang, Hailin

    Micro-electromechanical systems research is producing increasingly sophisticated tools for nanophononic applications. Such technology is well-suited for achieving chip-based, integrated acoustic control of solid-state quantum systems. We demonstrate such acoustic control in an important solid-state qubit, the diamond nitrogen-vacancy (NV) center. Using an interdigitated transducer to generate a surface acoustic wave (SAW) field in a bulk diamond, we observe phonon-assisted sidebands in the optical excitation spectrum of a single NV center. This exploits the strong strain sensitivity of the NV excited states. The mechanical frequencies far exceed the relevant optical linewidths, reaching the resolved-sideband regime. This enables us to use the SAW field for driving Rabi oscillations on the phonon-assisted optical transition. These results stimulate the further integration of SAW-based technologies with the NV center system.

  20. Acoustic non-diffracting Airy beam

    International Nuclear Information System (INIS)

    Lin, Zhou; Guo, Xiasheng; Tu, Juan; Ma, Qingyu; Wu, Junru; Zhang, Dong

    2015-01-01

    The acoustic non-diffracting Airy beam as its optical counterpart has unique features of self-bending and self-healing. The complexity of most current designs handicaps its applications. A simple design of an acoustic source capable of generating multi-frequency and broad-band acoustic Airy beam has been theoretically demonstrated by numerical simulations. In the design, a piston transducer is corrugated to induce spatial phase variation for transducing the Airy function. The piston's surface is grooved in a pattern that the width of each groove corresponds to the half wavelength of Airy function. The resulted frequency characteristics and its dependence on the size of the piston source are also discussed. This simple design may promote the wide applications of acoustic Airy beam particularly in the field of medical ultrasound

  1. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    Science.gov (United States)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in

  2. Analysis of Flame Extinguishment and Height in Low Frequency Acoustically Excited Methane Jet Diffusion Flame

    Science.gov (United States)

    Zong, Ruowen; Kang, Ruxue; Liu, Chen; Zhang, Zhiyang; Zhi, Youran

    2018-01-01

    The exploration of microgravity conditions in space is increasing and existing fire extinguishing technology is often inadequate for fire safety in this special environment. As a result, improving the efficiency of portable extinguishers is of growing importance. In this work, a visual study of the effects on methane jet diffusion flames by low frequency sound waves is conducted to assess the extinguishing ability of sound waves. With a small-scale sound wave extinguishing bench, the extinguishing ability of certain frequencies of sound waves are identified, and the response of the flame height is observed and analyzed. Results show that the flame structure changes with disturbance due to low frequency sound waves of 60-100 Hz, and quenches at effective frequencies in the range of 60-90 Hz. In this range, 60 Hz is considered to be the quick extinguishing frequency, while 70-90 Hz is the stable extinguishing frequency range. For a fixed frequency, the flame height decreases with sound pressure level (SPL). The flame height exhibits the greatest sensitivity to the 60 Hz acoustic waves, and the least to the 100 Hz acoustic waves. The flame height decreases almost identically with disturbance by 70-90 Hz acoustic waves.

  3. Surface acoustic wave actuated cell sorting (SAWACS).

    Science.gov (United States)

    Franke, T; Braunmüller, S; Schmid, L; Wixforth, A; Weitz, D A

    2010-03-21

    We describe a novel microfluidic cell sorter which operates in continuous flow at high sorting rates. The device is based on a surface acoustic wave cell-sorting scheme and combines many advantages of fluorescence activated cell sorting (FACS) and fluorescence activated droplet sorting (FADS) in microfluidic channels. It is fully integrated on a PDMS device, and allows fast electronic control of cell diversion. We direct cells by acoustic streaming excited by a surface acoustic wave which deflects the fluid independently of the contrast in material properties of deflected objects and the continuous phase; thus the device underlying principle works without additional enhancement of the sorting by prior labelling of the cells with responsive markers such as magnetic or polarizable beads. Single cells are sorted directly from bulk media at rates as fast as several kHz without prior encapsulation into liquid droplet compartments as in traditional FACS. We have successfully directed HaCaT cells (human keratinocytes), fibroblasts from mice and MV3 melanoma cells. The low shear forces of this sorting method ensure that cells survive after sorting.

  4. Acoustically enhanced heat transport

    Energy Technology Data Exchange (ETDEWEB)

    Ang, Kar M.; Hung, Yew Mun; Tan, Ming K., E-mail: tan.ming.kwang@monash.edu [School of Engineering, Monash University Malaysia, 47500 Bandar Sunway, Selangor (Malaysia); Yeo, Leslie Y. [Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3001 (Australia); Friend, James R. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093 (United States)

    2016-01-15

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10{sup 6} Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξ{sub s} ∼ 10{sup −9} m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξ{sub s} ∼ 10{sup −8} m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10{sup −8} m with 10{sup 6} Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.

  5. Acoustic frequency filter based on anisotropic topological phononic crystals

    KAUST Repository

    Chen, Zeguo

    2017-11-02

    We present a design of acoustic frequency filter based on a two-dimensional anisotropic phononic crystal. The anisotropic band structure exhibits either a directional or a combined (global + directional) bandgap at certain frequency regions, depending on the geometry. When the time-reversal symmetry is broken, it may introduce a topologically nontrivial bandgap. The induced nontrivial bandgap and the original directional bandgap result in various interesting wave propagation behaviors, such as frequency filter. We develop a tight-binding model to characterize the effective Hamiltonian of the system, from which the contribution of anisotropy is explicitly shown. Different from the isotropic cases, the Zeeman-type splitting is not linear and the anisotropic bandgap makes it possible to achieve anisotropic propagation characteristics along different directions and at different frequencies.

  6. Acoustic frequency filter based on anisotropic topological phononic crystals

    KAUST Repository

    Chen, Zeguo; Zhao, Jiajun; Mei, Jun; Wu, Ying

    2017-01-01

    We present a design of acoustic frequency filter based on a two-dimensional anisotropic phononic crystal. The anisotropic band structure exhibits either a directional or a combined (global + directional) bandgap at certain frequency regions, depending on the geometry. When the time-reversal symmetry is broken, it may introduce a topologically nontrivial bandgap. The induced nontrivial bandgap and the original directional bandgap result in various interesting wave propagation behaviors, such as frequency filter. We develop a tight-binding model to characterize the effective Hamiltonian of the system, from which the contribution of anisotropy is explicitly shown. Different from the isotropic cases, the Zeeman-type splitting is not linear and the anisotropic bandgap makes it possible to achieve anisotropic propagation characteristics along different directions and at different frequencies.

  7. Enhanced sources of acoustic power surrounding AR 11429

    International Nuclear Information System (INIS)

    Donea, Alina; Hanson, Christopher

    2013-01-01

    Multi-frequency power maps of the local acoustic oscillations show acoustic enhancements (''acoustic-power halos'') at high frequencies surrounding large active region. Computational seismic holography reveals a high-frequency ''acoustic-emission halo'', or ''seismic glory'' surrounding large active regions. In this study, we have applied computational seismic holography to map the seismic seismic source density surrounding AR 11429. Studies of HMI/SDO Doppler data, shows that the ''acoustic halos'' and the ''seismic glories'' are prominent at high frequencies 5–8 mHz. We investigate morphological properties of acoustic-power and acoustic emission halos around an active region to see if they are spatially correlated. Details about the local magnetic field from vectormagnetograms of AR 11429 are included. We identify a 15'' region of seismic deficit power (dark moat) shielding the white-light boundary of the active region. The size of the seismic moat is related to region of intermediate magnetic field strength. The acoustic moat is circled by the halo of enhanced seismic amplitude as well as enhanced seismic emission. Overall, the results suggest that features are related. However, if we narrow the frequency band to 5.5 – 6.5 mHz, we find that the seismic source density dominates over the local acoustic power, suggesting the existence of sources that emit more energy downward into the solar interior than upward toward the solar surface.

  8. Development of Lightweight, Compact, Structurally-Integrated Acoustic Liners for Broadband Low-Frequency Noise Mitigation

    Science.gov (United States)

    Chambers, Andrew T.

    Airborne noise with a low dominant frequency content (scope of conventional acoustic noise mitigation techniques using liners, foams or claddings owing to mass and volume considerations. Its low evanescence contributes significantly to environmental noise pollution, and unwanted structural vibrations causing diminished efficiency, comfort, payload integrity and mission capabilities. An alternative approach using liner configurations with realistic mass and volume constraints having innovative 'folded' core geometries is investigated to ascertain its low-frequency noise absorption characteristics. In contrast to mass-driven approaches, the folded core approach relies on tailoring interactions between acoustic resonances to tune the liner's impedance to suit the dominant low-frequency content of the source. This allows to keep non-structural mass-addition to a minimum, while retaining an overall thickness comparable to conventional liners for these low-frequency liner designs. The relative acoustic performance of various candidate folded core designs is evaluated by means of a new composite metric termed the Low-Frequency Performance (LFP) factor, which is educed from the absorption coefficient spectrum obtained using Zwikker-Kosten Transmission Line (ZKTL) theory-based numerical studies. An LFP-based software tool is developed to determine optimal 3D cavity packing for a prescribed liner volume and target frequency range. ZKTL-based parametric studies on core dimensions and face sheet porosity are utilized for detailed design of test articles. Experimental verification of absorption coefficient spectra conducted using 3D printed test articles in a normal incidence acoustic impedance tube yield good correlation with simulations. More than 100 Hz of continuous bandwidth with an absorption coefficient greater than 0.6 is shown to be possible in the 300 to 400 Hz range with a 38.1-mm (1.5-inch) thick liner. Further, the influence of face sheet type, Mach number, and

  9. Fatigue level estimation of monetary bills based on frequency band acoustic signals with feature selection by supervised SOM

    Science.gov (United States)

    Teranishi, Masaru; Omatu, Sigeru; Kosaka, Toshihisa

    Fatigued monetary bills adversely affect the daily operation of automated teller machines (ATMs). In order to make the classification of fatigued bills more efficient, the development of an automatic fatigued monetary bill classification method is desirable. We propose a new method by which to estimate the fatigue level of monetary bills from the feature-selected frequency band acoustic energy pattern of banking machines. By using a supervised self-organizing map (SOM), we effectively estimate the fatigue level using only the feature-selected frequency band acoustic energy pattern. Furthermore, the feature-selected frequency band acoustic energy pattern improves the estimation accuracy of the fatigue level of monetary bills by adding frequency domain information to the acoustic energy pattern. The experimental results with real monetary bill samples reveal the effectiveness of the proposed method.

  10. A numerical study on acoustic behavior in gas turbine combustor with acoustic resonator

    International Nuclear Information System (INIS)

    Park, I Sun; Sohn, Chae Hoon

    2005-01-01

    Acoustic behavior in gas turbine combustor with acoustic resonator is investigated numerically by adopting linear acoustic analysis. Helmholtz-type resonator is employed as acoustic resonator to suppress acoustic instability passively. The tuning frequency of acoustic resonator is adjusted by varying its length. Through harmonic analysis, acoustic-pressure responses of chamber to acoustic excitation are obtained and the resonant acoustic modes are identified. Acoustic damping effect of acoustic resonator is quantified by damping factor. As the tuning frequency of acoustic resonator approaches the target frequency of the resonant mode to be suppressed, mode split from the original resonant mode to lower and upper modes appears and thereby complex patterns of acoustic responses show up. Considering mode split and damping effect as a function of tuning frequency, it is desirable to make acoustic resonator tuned to broad-band frequencies near the maximum frequency of those of the possible upper modes

  11. Measurement of pressure on a surface using bubble acoustic resonances

    International Nuclear Information System (INIS)

    Aldham, Ben; Manasseh, Richard; Liffman, Kurt; Šutalo, Ilija D; Illesinghe, Suhith; Ooi, Andrew

    2010-01-01

    The frequency response of gas bubbles as a function of liquid ambient pressure was measured and compared with theory. A bubble size with equivalent spherical radius of 2.29 mm was used over a frequency range of 1000–1500 Hz. The ultimate aim is to develop an acoustic sensor that can measure static pressure and is sensitive to variations as small as a few kPa. The classical bubble resonance frequency is known to vary with ambient pressure. Experiments were conducted with a driven bubble in a pressurizable tank with a signal processing system designed to extract the resonant peak. Since the background response of the containing tank is significant, particularly near tank-modal resonances, it must be carefully removed from the bubble response signal. A dual-hydrophone method was developed to allow rapid and reliable real-time measurements. The expected pressure dependence was found. In order to obtain a reasonable match with theory, the classical theory was modified by the introduction of a 'mirror bubble' to account for the influence of a nearby surface. (technical design note)

  12. Model Equation for Acoustic Nonlinear Measurement of Dispersive Specimens at High Frequency

    Science.gov (United States)

    Zhang, Dong; Kushibiki, Junichi; Zou, Wei

    2006-10-01

    We present a theoretical model for acoustic nonlinearity measurement of dispersive specimens at high frequency. The nonlinear Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation governs the nonlinear propagation in the SiO2/specimen/SiO2 multi-layer medium. The dispersion effect is considered in a special manner by introducing the frequency-dependant sound velocity in the KZK equation. Simple analytic solutions are derived by applying the superposition technique of Gaussian beams. The solutions are used to correct the diffraction and dispersion effects in the measurement of acoustic nonlinearity of cottonseed oil in the frequency range of 33-96 MHz. Regarding two different ultrasonic devices, the accuracies of the measurements are improved to ±2.0% and ±1.3% in comparison with ±9.8% and ±2.9% obtained from the previous plane wave model.

  13. High-spatial-resolution sub-surface imaging using a laser-based acoustic microscopy technique.

    Science.gov (United States)

    Balogun, Oluwaseyi; Cole, Garrett D; Huber, Robert; Chinn, Diane; Murray, Todd W; Spicer, James B

    2011-01-01

    Scanning acoustic microscopy techniques operating at frequencies in the gigahertz range are suitable for the elastic characterization and interior imaging of solid media with micrometer-scale spatial resolution. Acoustic wave propagation at these frequencies is strongly limited by energy losses, particularly from attenuation in the coupling media used to transmit ultrasound to a specimen, leading to a decrease in the depth in a specimen that can be interrogated. In this work, a laser-based acoustic microscopy technique is presented that uses a pulsed laser source for the generation of broadband acoustic waves and an optical interferometer for detection. The use of a 900-ps microchip pulsed laser facilitates the generation of acoustic waves with frequencies extending up to 1 GHz which allows for the resolution of micrometer-scale features in a specimen. Furthermore, the combination of optical generation and detection approaches eliminates the use of an ultrasonic coupling medium, and allows for elastic characterization and interior imaging at penetration depths on the order of several hundred micrometers. Experimental results illustrating the use of the laser-based acoustic microscopy technique for imaging micrometer-scale subsurface geometrical features in a 70-μm-thick single-crystal silicon wafer with a (100) orientation are presented.

  14. Source Identification in Structural Acoustics with an Inverse Frequency Response Function Technique

    NARCIS (Netherlands)

    Visser, Rene

    2002-01-01

    Inverse source identification based on acoustic measurements is essential for the investigation and understanding of sound fields generated by structural vibrations of various devices and machinery. Acoustic pressure measurements performed on a grid in the nearfield of a surface can be used to

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

    Directory of Open Access Journals (Sweden)

    Zhi Chen

    2012-08-01

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

  16. High Frequency Acoustic Microscopy for the Determination of Porosity and Young's Modulus in High Burnup Uranium Dioxide Nuclear Fuel

    Science.gov (United States)

    Marchetti, Mara; Laux, Didier; Cappia, Fabiola; Laurie, M.; Van Uffelen, P.; Rondinella, V. V.; Wiss, T.; Despaux, G.

    2016-06-01

    During irradiation UO2 nuclear fuel experiences the development of a non-uniform distribution of porosity which contributes to establish varying mechanical properties along the radius of the pellet. Radial variations of both porosity and elastic properties in high burnup UO2 pellet can be investigated via high frequency acoustic microscopy. For this purpose ultrasound waves are generated by a piezoelectric transducer and focused on the sample, after having travelled through a coupling liquid. The elastic properties of the material are related to the velocity of the generated Rayleigh surface wave (VR). A UO2 pellet with a burnup of 67 GWd/tU was characterized using the acoustic microscope installed in the hot cells of the JRC-ITU at a 90 MHz frequency, with methanol as coupling liquid. VR was measured at different radial positions. A good agreement was found, when comparing the porosity values obtained via acoustic microscopy with those determined using SEM image analysis, especially in the areas close to the centre. In addition, Young's modulus was calculated and its radial profile was correlated to the corresponding burnup profile and to the hardness radial profile data obtained by Vickers micro-indentation.

  17. Fundamentals of Acoustics. Psychoacoustics and Hearing. Acoustical Measurements

    Science.gov (United States)

    Begault, Durand R.; Ahumada, Al (Technical Monitor)

    1997-01-01

    These are 3 chapters that will appear in a book titled "Building Acoustical Design", edited by Charles Salter. They are designed to introduce the reader to fundamental concepts of acoustics, particularly as they relate to the built environment. "Fundamentals of Acoustics" reviews basic concepts of sound waveform frequency, pressure, and phase. "Psychoacoustics and Hearing" discusses the human interpretation sound pressure as loudness, particularly as a function of frequency. "Acoustic Measurements" gives a simple overview of the time and frequency weightings for sound pressure measurements that are used in acoustical work.

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

    Science.gov (United States)

    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.

  19. Modal analysis and cut-off conditions of multichannel surface-acoustic-waveguide structures.

    Science.gov (United States)

    Griffel, G; Golan, G; Ruschin, S; Seidman, A; Croitoru, N

    1988-01-01

    Multichannel guides for surface acoustic waves can improve the efficiency of SAW (surface acoustic-wave) devices significantly. Focusing, steering, and modulating the propagating acoustical modes can be achieved similarly to optical waveguided devices. A general formulation is presented for the analysis of the lateral waveguiding properties of Rayleigh modes in surfaces loaded with deposited strips of different materials. General expressions are obtained for the number of modes and cutoff conditions in these structures. As examples of applications, a simple directional coupler and an electrically controlled coupler are proposed.

  20. ZnO film for application in surface acoustic wave device

    International Nuclear Information System (INIS)

    Du, X Y; Fu, Y Q; Tan, S C; Luo, J K; Flewitt, A J; Maeng, S; Kim, S H; Choi, Y J; Lee, D S; Park, N M; Park, J; Milne, W I

    2007-01-01

    High quality, c-axis oriented zinc oxide (ZnO) thin films were grown on silicon substrate using RF magnetron sputtering. Surface acoustic wave (SAW) devices were fabricated with different thickness of ZnO ranging from 1.2 to 5.5 μmUm and the frequency responses were characterized using a network analyzer. Thick ZnO films produce the strongest transmission and reflection signals from the SAW devices. The SAW propagation velocity is also strongly dependent on ZnO film thickness. The performance of the ZnO SAW devices could be improved with addition of a SiO 2 layer, in name of reflection signal amplitude and phase velocity of Rayleigh wave

  1. Time domain acoustic contrast control implementation of sound zones for low-frequency input signals

    DEFF Research Database (Denmark)

    Schellekens, Daan H. M.; Møller, Martin Bo; Olsen, Martin

    2016-01-01

    Sound zones are two or more regions within a listening space where listeners are provided with personal audio. Acoustic contrast control (ACC) is a sound zoning method that maximizes the average squared sound pressure in one zone constrained to constant pressure in other zones. State......-of-the-art time domain broadband acoustic contrast control (BACC) methods are designed for anechoic environments. These methods are not able to realize a flat frequency response in a limited frequency range within a reverberant environment. Sound field control in a limited frequency range is a requirement...... to accommodate the effective working range of the loudspeakers. In this paper, a new BACC method is proposed which results in an implementation realizing a flat frequency response in the target zone. This method is applied in a bandlimited low-frequency scenario where the loudspeaker layout surrounds two...

  2. Spatial filtering of audible sound with acoustic landscapes

    Science.gov (United States)

    Wang, Shuping; Tao, Jiancheng; Qiu, Xiaojun; Cheng, Jianchun

    2017-07-01

    Acoustic metasurfaces manipulate waves with specially designed structures and achieve properties that natural materials cannot offer. Similar surfaces work in audio frequency range as well and lead to marvelous acoustic phenomena that can be perceived by human ears. Being intrigued by the famous Maoshan Bugle phenomenon, we investigate large scale metasurfaces consisting of periodic steps of sizes comparable to the wavelength of audio frequency in both time and space domains. We propose a theoretical method to calculate the scattered sound field and find that periodic corrugated surfaces work as spatial filters and the frequency selective character can only be observed at the same side as the incident wave. The Maoshan Bugle phenomenon can be well explained with the method. Finally, we demonstrate that the proposed method can be used to design acoustical landscapes, which transform impulsive sound into famous trumpet solos or other melodious sound.

  3. High frequency acoustic microscopy for the determination of porosity and Young's modulus in high burnup uranium dioxide nuclear fuel

    International Nuclear Information System (INIS)

    Marchetti, M.; Laux, D.; Cappia, F.; Laurie, M.; Van Uffelen, P.; Rondinella, V.V.; Despaux, G.

    2015-01-01

    During irradiation UO 2 nuclear fuel experiences the development of a non-uniform distribution of porosity which contributes to establish varying mechanical properties along the radius of the pellet. Radial variations of the porosity and of elastic properties in high burnup UO 2 pellet can be investigated via high frequency acoustic microscopy. Ultrasound waves are generated by a piezoelectric transducer and focused on the sample, after having travelled through a coupling liquid. The elastic properties of the material are related to the velocity of the generated Rayleigh surface wave (VR). A 67 MWd/kgU UO 2 pellet was characterized using the acoustic microscope installed in the hot cells of the Institute of Transuranium Elements: 90 MHz frequency was applied, methanol was used as coupling liquid and VR was measured at different radial positions. By comparing the porosity values obtained via acoustic microscopy with those determined using ceramographic image analysis a good agreement was found, especially in the areas close to the centre. In addition Young's modulus was calculated and its radial profile was correlated to the corresponding burnup profile. (authors)

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

    Science.gov (United States)

    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.

  5. Determination of acoustic properties of thin polymer films utilizing the frequency dependence of the reflection coefficient of ultrasound.

    Science.gov (United States)

    Tohmyoh, Hironori; Sakamoto, Yuhei

    2015-11-01

    This paper reports on a technique to measure the acoustic properties of a thin polymer film utilizing the frequency dependence of the reflection coefficient of ultrasound reflected back from a system comprising a reflection plate, the film, and a material that covers the film. The frequency components of the echo reflected from the back of the plate, where the film is attached, take their minimum values at the resonant frequency, and from these frequency characteristics, the acoustic impedance, sound velocity, and the density of the film can be determined. We applied this technique to characterize an ion exchange membrane, which has high water absorbability, and successfully determined the acoustic properties of the membrane without getting it wet.

  6. An open-structure sound insulator against low-frequency and wide-band acoustic waves

    Science.gov (United States)

    Chen, Zhe; Fan, Li; Zhang, Shu-yi; Zhang, Hui; Li, Xiao-juan; Ding, Jin

    2015-10-01

    To block sound, i.e., the vibration of air, most insulators are based on sealed structures and prevent the flow of the air. In this research, an acoustic metamaterial adopting side structures, loops, and labyrinths, arranged along a main tube, is presented. By combining the accurately designed side structures, an extremely wide forbidden band with a low cut-off frequency of 80 Hz is produced, which demonstrates a powerful low-frequency and wide-band sound insulation ability. Moreover, by virtue of the bypass arrangement, the metamaterial is based on an open structure, and thus air flow is allowed while acoustic waves can be insulated.

  7. One-dimensional rigid film acoustic metamaterials

    Science.gov (United States)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng

    2015-11-01

    We have designed a 1D film-type acoustic metamaterial structure consisting of several polymer films directly stacked on each other. It is experimentally revealed that the mass density law can be broken by such structures in the low frequency range. By comparing the sound transmission loss (STL) curves of structures with different numbers of cycles, materials and incident sound directions, several physical properties of the 1D film-type acoustic metamaterial are revealed, which consist of cyclical effects, surface effects and orientation effects. It is suggested that the excellent low frequency sound insulation capacity is influenced by both the cycle number and the stiffness of the film surface. Meanwhile, the surface effect plays a dominant role among these physical properties. Due to the surface acoustic property, for structures with a particular combination form, the STL dominated by the cyclical effects may reach saturation with increasing number of construction periods. Moreover, in some cases, the sound insulation ability is diverse for different sound incidence directions. This kind of 1D film-type periodic structure with these special physical properties provides a new concept for the regulation of sound waves.

  8. One-dimensional rigid film acoustic metamaterials

    International Nuclear Information System (INIS)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng

    2015-01-01

    We have designed a 1D film-type acoustic metamaterial structure consisting of several polymer films directly stacked on each other. It is experimentally revealed that the mass density law can be broken by such structures in the low frequency range. By comparing the sound transmission loss (STL) curves of structures with different numbers of cycles, materials and incident sound directions, several physical properties of the 1D film-type acoustic metamaterial are revealed, which consist of cyclical effects, surface effects and orientation effects. It is suggested that the excellent low frequency sound insulation capacity is influenced by both the cycle number and the stiffness of the film surface. Meanwhile, the surface effect plays a dominant role among these physical properties. Due to the surface acoustic property, for structures with a particular combination form, the STL dominated by the cyclical effects may reach saturation with increasing number of construction periods. Moreover, in some cases, the sound insulation ability is diverse for different sound incidence directions. This kind of 1D film-type periodic structure with these special physical properties provides a new concept for the regulation of sound waves. (paper)

  9. Acoustic biosensors.

    Science.gov (United States)

    Fogel, Ronen; Limson, Janice; Seshia, Ashwin A

    2016-06-30

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  10. Resonance cones below the ion cyclotron frequency: theory and experiment

    International Nuclear Information System (INIS)

    Bellan, P.

    1976-03-01

    The resonance cones existing below the ion cyclotron frequency, ω/sub c/sub i//, are shown, theoretically and experimentally, to be the asymptotes of hyperbolic constant-phase surfaces of low-frequency ion acoustic waves. Above ω/sub c/sub i// the surfaces transform into ellipses that are related to the electrostatic ion cyclotron waves and ion acoustic waves

  11. Geodesic acoustic eigenmode for tokamak equilibrium with maximum of local GAM frequency

    Energy Technology Data Exchange (ETDEWEB)

    Lakhin, V.P. [NRC “Kurchatov Institute”, Moscow (Russian Federation); Sorokina, E.A., E-mail: sorokina.ekaterina@gmail.com [NRC “Kurchatov Institute”, Moscow (Russian Federation); Peoples' Friendship University of Russia, Moscow (Russian Federation)

    2014-01-24

    The geodesic acoustic eigenmode for tokamak equilibrium with the maximum of local GAM frequency is found analytically in the frame of MHD model. The analysis is based on the asymptotic matching technique.

  12. Thermo-acoustic instabilities of high-frequency combustion in rocket engines; Instabilites thermo-acoustiques de combustion haute-frequence dans les moteurs fusees

    Energy Technology Data Exchange (ETDEWEB)

    Cheuret, F

    2005-10-15

    Rocket motors are confined environments where combustion occurs in extreme conditions. Combustion instabilities can occur at high frequencies; they are tied to the acoustic modes of the combustion chamber. A common research chamber, CRC, allows us to study the response of a turbulent two-phase flame to acoustic oscillations of low or high amplitudes. The chamber is characterised under cold conditions to obtain, in particular, the relative damping coefficient of acoustic oscillations. The structure and frequency of the modes are determined in the case where the chamber is coupled to a lateral cavity. We have used a powder gun to study the response to a forced acoustic excitation at high amplitude. The results guide us towards shorter flames. The injectors were then modified to study the combustion noise level as a function of injection conditions. The speed of the gas determines whether the flames are attached or lifted. The noise level of lifted flames is higher. That of attached flames is proportional to the Weber number. The shorter flames whose length is less than the radius of the CRC, necessary condition to obtain an effective coupling, are the most sensitive to acoustic perturbations. The use of a toothed wheel at different positions in the chamber allowed us to obtain informations on the origin of the thermo-acoustic coupling, main objective of this thesis. The flame is sensitive to pressure acoustic oscillations, with a quasi-zero response time. These observations suggest that under the conditions of the CRC, we observe essentially the response of chemical kinetics to pressure oscillations. (author)

  13. Investigation of bulk acoustic microwaves excited by an interdigital transducer

    Directory of Open Access Journals (Sweden)

    Reshotka O. G.

    2015-12-01

    Full Text Available Excitation of bulk and surface acoustic waves with the interdigital transducer (IDT, which is deposited on the surface of piezoelectric crystal, is widely used in the development of devices in acoustoelectronics and in the design of the microwave acousto-optic deflectors. Excitation of bulk acoustic waves by IDT in the devices on surface acoustic waves leads to the appearance of spurious signals. At the same time excitation of bulk acoustic waves with IDT from the surface of lithium niobate crystals allows creating high frequency acousto-optic deflectors, which makes possible to significantly simplify the technology of their production. Therefore, significant attention is paid to the task of excitation and distribution of bulk acoustic waves with IDT including recent times by the method of simulation of their excitation and distribution. The obtained theoretical results require experimental verification. This paper documents the visualization of acoustic beams excited with IDT from the XY-surface of lithium niobate crystals. The Bragg cells with LiNbO3 crystals coated with IDT with a different period of electrodes were manufactured for the experimental research of excitation and distribution of bulk acoustic waves. Visualization results have shown that the acoustic waves excited with IDT distribute in both the Fresnel zone and the Fraunhofer zone. The length of these zones is caused by individual elementary emitters of which consists the IDT (by their size. At the same time the far zone for IDT is located at distances much greater than the actual size of the LiNbO3 crystals. This peculiarity is not always taken into account when calculating diffraction. The achieved results can be used to design high-frequency acousto-optic devices, as well as in the development of devices based on surface acoustic waves.

  14. An acoustic metamaterial composed of multi-layer membrane-coated perforated plates for low-frequency sound insulation

    Science.gov (United States)

    Fan, Li; Chen, Zhe; Zhang, Shu-yi; Ding, Jin; Li, Xiao-juan; Zhang, Hui

    2015-04-01

    Insulating against low-frequency sound (below 500 Hz ) remains challenging despite the progress that has been achieved in sound insulation and absorption. In this work, an acoustic metamaterial based on membrane-coated perforated plates is presented for achieving sound insulation in a low-frequency range, even covering the lower audio frequency limit, 20 Hz . Theoretical analysis and finite element simulations demonstrate that this metamaterial can effectively block acoustic waves over a wide low-frequency band regardless of incident angles. Two mechanisms, non-resonance and monopolar resonance, operate in the metamaterial, resulting in a more powerful sound insulation ability than that achieved using periodically arranged multi-layer solid plates.

  15. Long Elastic Open Neck Acoustic Resonator for low frequency absorption

    Science.gov (United States)

    Simon, Frank

    2018-05-01

    Passive acoustic liners, used in aeronautic engine nacelles to reduce radiated fan noise, have a quarter-wavelength behavior, because of perforated sheets backed by honeycombs (with one or two degrees of freedom). However, their acoustic absorption ability is naturally limited to medium and high frequencies because of constraints in thickness. The low ratio "plate thickness/hole diameter" generates impedance levels dependent on the incident sound pressure level and the grazing mean flow (by a mechanism of nonlinear dissipation through vortex shedding), which penalises the optimal design of liners. The aim of this paper is to overcome this problem by a concept called LEONAR ("Long Elastic Open Neck Acoustic Resonator"), in which a perforated plate is coupled with tubes of variable lengths inserted in a limited volume of a back cavity. To do this, experimental and theoretical studies, using different types of liners (material nature, hole diameter, tube length, cavity thickness) are described in this paper. It is shown that the impedance can be precisely determined with an analytical approach based on parallel transfer matrices of tubes coupled to the cavity. Moreover, the introduction of tubes in a cavity of a conventional resonator generates a significant shift in the frequency range of absorption towards lower frequencies or allows a reduction of cavity thickness. The impedance is practically independent of sound pressure level because of a high ratio "tube length/tube hole diameter". Finally, a test led in an aeroacoustic bench suggests that a grazing flow at a bulk Mach number of 0.3 has little impact on the impedance value. These first results allow considering these resonators with linear behavior as an alternative to classical resonators, in particular, as needed for future Ultra High Bypass Ratio engines with shorter and thinner nacelles.

  16. In Situ Evaluation of Density, Viscosity and Thickness of Adsorbed Soft Layers by Combined Surface Acoustic Wave and Surface Plasmon Resonance

    OpenAIRE

    Francis, L.; Friedt, J. -M.; Zhou, C.; Bertrand, P.

    2003-01-01

    We show the theoretical and experimental combination of acoustic and optical methods for the in situ quantitative evaluation of the density, the viscosity and the thickness of soft layers adsorbed on chemically tailored metal surfaces. For the highest sensitivity and an operation in liquids, a Love mode surface acoustic wave (SAW) sensor with a hydrophobized gold coated sensing area is the acoustic method, while surface plasmon resonance (SPR) on the same gold surface as the optical method is...

  17. Gravity enhanced acoustic levitation method and apparatus

    Science.gov (United States)

    Barmatz, M. B.; Allen, J. L.; Granett, D. (Inventor)

    1985-01-01

    An acoustic levitation system is provided for acoustically levitating an object by applying a single frequency from a transducer into a resonant chamber surrounding the object. The chamber includes a stabilizer location along its height, where the side walls of the chamber are angled so they converge in an upward direction. When an acoustic standing wave pattern is applied between the top and bottom of the chamber, a levitation surface within the stabilizer does not lie on a horizontal plane, but instead is curved with a lowermost portion near the vertical axis of the chamber. As a result, an acoustically levitated object is urged by gravity towards the lowermost location on the levitation surface, so the object is kept away from the side walls of the chamber.

  18. An acoustic vector based approach to locate low frequency noise sources in 3D

    NARCIS (Netherlands)

    Bree, H.-E. de; Ostendorf, C.; Basten, T.

    2009-01-01

    Although low frequency noise is an issue of huge societal importance, traditional acoustic testing methods have limitations in finding the low frequency source. It is hard to determine the direction of the noise using traditional microphones. Three dimensional sound probes capturing the particle

  19. The near-field acoustic levitation of high-mass rotors

    International Nuclear Information System (INIS)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B.

    2014-01-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope

  20. The near-field acoustic levitation of high-mass rotors

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2014-10-15

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  1. The near-field acoustic levitation of high-mass rotors.

    Science.gov (United States)

    Hong, Z Y; Lü, P; Geng, D L; Zhai, W; Yan, N; Wei, B

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  2. Acoustic loss and frequency stability studies of gamma- and proton-irradiated alpha-quartz crystal resonators

    International Nuclear Information System (INIS)

    Suter, J.J.

    1988-01-01

    This work examines the radiation-induced effects in alpha-quartz crystal resonators and distinguishes the various acoustic losses responsible for the frequency susceptibility over these dose ranges. Simulation of low-earth-orbit proton radiation was accomplished with protons from the Harvard University Cyclotron using a novel proton-beam modulator, which was designed to emulate a 10-120 MeV proton spectrum for the radiation susceptibility and acoustic-loss studies on AT quartz resonators. Quartz resonators having aluminum defect center concentrations between 0.01 and 19 ppm experienced proton-induced frequency shifts not correlated to their aluminum impurity content. It was also found that AT quartz resonators of the electrode-less BVA design experienced the smallest frequency shifts. Experiments conducted with 1.25-MeV gamma rays from a cobalt 60 source demonstrated identical frequency shifts in quartz, indicating that the energy losses of gamma rays and protons in quartz over the examined dose and energy ranges were similar. Acoustic-loss measurements conducted over the 0.3-70 K range revealed that the phonon-phonon and two-level energy excitation peaks near 20 and 5 K, respectively, were not affected by proton or cobalt 60 radiation

  3. High frequency acoustic microscopy for the determination of porosity and Young's modulus in high burnup uranium dioxide nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti, M. [European Commission, Joint Research Centre, Institute for Transuranium Elements P.O. Box 2340 76125 Karlsruhe (Germany); University of Montpellier, IES, UMR 5214, F-34000, Montpellier (France); Laux, D. [University of Montpellier, IES, UMR 5214, F-34000, Montpellier (France); CNRS, IES, UMR 5214, F-34000, Montpellier (France); Cappia, F. [European Commission, Joint Research Centre, Institute for Transuranium Elements P.O. Box 2340 76125 Karlsruhe (Germany); Technische Universitaet Muenchen, Department of Nuclear Engineering, Boltzmannstrasse 15, 85747 Garching bei Munchen (Germany); Laurie, M.; Van Uffelen, P.; Rondinella, V.V. [European Commission, Joint Research Centre, Institute for Transuranium Elements P.O. Box 2340 76125 Karlsruhe (Germany); Despaux, G. [University of Montpellier, IES, UMR 5214, F-34000, Montpellier (France); CNRS, IES, UMR 5214, F-34000, Montpellier (France)

    2015-07-01

    During irradiation UO{sub 2} nuclear fuel experiences the development of a non-uniform distribution of porosity which contributes to establish varying mechanical properties along the radius of the pellet. Radial variations of the porosity and of elastic properties in high burnup UO{sub 2} pellet can be investigated via high frequency acoustic microscopy. Ultrasound waves are generated by a piezoelectric transducer and focused on the sample, after having travelled through a coupling liquid. The elastic properties of the material are related to the velocity of the generated Rayleigh surface wave (VR). A 67 MWd/kgU UO{sub 2} pellet was characterized using the acoustic microscope installed in the hot cells of the Institute of Transuranium Elements: 90 MHz frequency was applied, methanol was used as coupling liquid and VR was measured at different radial positions. By comparing the porosity values obtained via acoustic microscopy with those determined using ceramographic image analysis a good agreement was found, especially in the areas close to the centre. In addition Young's modulus was calculated and its radial profile was correlated to the corresponding burnup profile. (authors)

  4. Electromagnetic-acoustic coupling in ferromagnetic metals at liquid-helium temperatures

    DEFF Research Database (Denmark)

    Gordon, R A

    1981-01-01

    Electromagnetic-acoustic coupling at the surface and in the bulk of ferromagnetic metals at liquid-helium temperatures has been studied using electromagnetically excited acoustic standing-wave resonances at MHz frequencies in a number of ferromagnetic metals and alloys of commercial interest...

  5. Near-surface viscosity measurements with a love acoustic wave device

    International Nuclear Information System (INIS)

    Collings, A.F.; Cooper, B.J.; Lappas, S.; Sor, J.A.

    1999-01-01

    Full text: In the last decade, considerable research effort has been directed towards interfacing piezoelectric transducers with biological detection systems to produce efficient and highly selective biosensors. Several types of piezoelectric or, more specifically, acoustic wave transducers have been investigated. Our group has developed Love wave (guided surface skimming wave) devices which are made by attaching a thin overlayer with the appropriate acoustic properties to the surface of a conventional surface horizontal mode device. An optimised layer concentrates most of the propagating wave energy in the guiding layer and can improve the device sensitivity in detecting gas-phase mass loading on the surface some 20- to 40-fold. Love wave devices used in liquid phase sensing will also respond to viscous, as well as mass, loading on the device surface. We have studied the propagation of viscous waves into liquid sitting on a Love wave device both theoretically and experimentally. Modelling of the effect of a viscous liquid layer on a Love wave propagating in a layered medium predicts the velocity profile in the solid substrate and in the adjoining liquid. This is a function of the thickness of the guiding layer, the elastic properties of the guiding layer and the piezoelectric substrate, and of the viscosity and density of the liquid layer. We report here on measurements of the viscosity of aqueous glycerine solutions made with a quartz Love wave device with a 5.5 μm SiO 2 guiding layer. The linear relationship between the decrease in the device frequency and the square root of the viscosity density product is accurately observed at Newtonian viscosities. At higher viscosities, there is an increase in damping, the insertion loss of the device saturates, Δf is no longer proportional to (ηp) l/2 and reaches a maximum. We also show results for the determination of the gelation time in protein and inorganic aqueous gels and for the rate of change of viscosity with

  6. Acousto-optical interaction of surface acoustic and optical waves in a two-dimensional phoxonic crystal hetero-structure cavity.

    Science.gov (United States)

    Ma, Tian-Xue; Zou, Kui; Wang, Yue-Sheng; Zhang, Chuanzeng; Su, Xiao-Xing

    2014-11-17

    Phoxonic crystal is a promising material for manipulating sound and light simultaneously. In this paper, we theoretically demonstrate the propagation of acoustic and optical waves along the truncated surface of a two-dimensional square-latticed phoxonic crystal. Further, a phoxonic crystal hetero-structure cavity is proposed, which can simultaneously confine surface acoustic and optical waves. The interface motion and photoelastic effects are taken into account in the acousto-optical coupling. The results show obvious shifts in eigenfrequencies of the photonic cavity modes induced by different phononic cavity modes. The symmetry of the phononic cavity modes plays a more important role in the single-phonon exchange process than in the case of the multi-phonon exchange. Under the same deformation, the frequency shift of the photonic transverse electric mode is larger than that of the transverse magnetic mode.

  7. Surface acoustic wave sensors with Graphene/PANI nanocomposites for nitric oxide detection

    Science.gov (United States)

    Wang, Beibei; Zheng, Lei; Zhou, Lingling

    2017-12-01

    Surface acoustic wave sensors with grapheme/PANI nanocomposite sensitive films for detecting nitric oxide (NO) were fabricated and experimentally studied. Morphological characterization and functionalization of the sensing material were explored using SEM and FTIR, respectively. The study of sensor response compared film sensitivity, response time, reversibility, and limit of detection for nanocomposite films, pure grapheme and pure PANI to the detection of NO. The response and recovery times were 40s and 20s when detecting 4ppm NO, respectively. The frequency response was discovered to be linear in the NO concentration range 1-50 ppm. The nanocomposite sensors had improved sensitivities compared to the polymer devices, and better response times.

  8. Auto-identification of engine fault acoustic signal through inverse trigonometric instantaneous frequency analysis

    Directory of Open Access Journals (Sweden)

    Dayong Ning

    2016-03-01

    Full Text Available The acoustic signals of internal combustion engines contain valuable information about the condition of engines. These signals can be used to detect incipient faults in engines. However, these signals are complex and composed of a faulty component and other noise signals of background. As such, engine conditions’ characteristics are difficult to extract through wavelet transformation and acoustic emission techniques. In this study, an instantaneous frequency analysis method was proposed. A new time–frequency model was constructed using a fixed amplitude and a variable cycle sine function to fit adjacent points gradually from a time domain signal. The instantaneous frequency corresponds to single value at any time. This study also introduced instantaneous frequency calculation on the basis of an inverse trigonometric fitting method at any time. The mean value of all local maximum values was then considered to identify the engine condition automatically. Results revealed that the mean of local maximum values under faulty conditions differs from the normal mean. An experiment case was also conducted to illustrate the availability of the proposed method. Using the proposed time–frequency model, we can identify engine condition and determine abnormal sound produced by faulty engines.

  9. Acoustic characterization of a nonlinear vibroacoustic absorber at low frequencies and high sound levels

    Science.gov (United States)

    Chauvin, A.; Monteil, M.; Bellizzi, S.; Côte, R.; Herzog, Ph.; Pachebat, M.

    2018-03-01

    A nonlinear vibroacoustic absorber (Nonlinear Energy Sink: NES), involving a clamped thin membrane made in Latex, is assessed in the acoustic domain. This NES is here considered as an one-port acoustic system, analyzed at low frequencies and for increasing excitation levels. This dynamic and frequency range requires a suitable experimental technique, which is presented first. It involves a specific impedance tube able to deal with samples of sufficient size, and reaching high sound levels with a guaranteed linear response thank's to a specific acoustic source. The identification method presented here requires a single pressure measurement, and is calibrated from a set of known acoustic loads. The NES reflection coefficient is then estimated at increasing source levels, showing its strong level dependency. This is presented as a mean to understand energy dissipation. The results of the experimental tests are first compared to a nonlinear viscoelastic model of the membrane absorber. In a second step, a family of one degree of freedom models, treated as equivalent Helmholtz resonators is identified from the measurements, allowing a parametric description of the NES behavior over a wide range of levels.

  10. Observation of sagittal X-ray diffraction by surface acoustic waves in Bragg geometry.

    Science.gov (United States)

    Vadilonga, Simone; Zizak, Ivo; Roshchupkin, Dmitry; Evgenii, Emelin; Petsiuk, Andrei; Leitenberger, Wolfram; Erko, Alexei

    2017-04-01

    X-ray Bragg diffraction in sagittal geometry on a Y-cut langasite crystal (La 3 Ga 5 SiO 14 ) modulated by Λ = 3 µm Rayleigh surface acoustic waves was studied at the BESSY II synchrotron radiation facility. Owing to the crystal lattice modulation by the surface acoustic wave diffraction, satellites appear. Their intensity and angular separation depend on the amplitude and wavelength of the ultrasonic superlattice. Experimental results are compared with the corresponding theoretical model that exploits the kinematical diffraction theory. This experiment shows that the propagation of the surface acoustic waves creates a dynamical diffraction grating on the crystal surface, and this can be used for space-time modulation of an X-ray beam.

  11. Marble Ageing Characterization by Acoustic Waves

    Science.gov (United States)

    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

  12. Spectrum of the seismic-electromagnetic and acoustic waves caused by seismic and volcano activity

    Directory of Open Access Journals (Sweden)

    S. Koshevaya

    2005-01-01

    Full Text Available Modeling of the spectrum of the seismo-electromagnetic and acoustic waves, caused by seismic and volcanic activity, has been done. This spectrum includes the Electromagnetic Emission (EME, due to fracturing piezoelectrics in rocks and the Acoustic Emission (AE, caused by the excitation and the nonlinear passage of acoustic waves through the Earth's crust, the atmosphere, and the ionosphere. The investigated mechanism of the EME uses the model of fracturing and the crack motion. For its analysis, we consider a piezoelectric crystal under mechanical stresses, which cause the uniform crack motion, and, consequently, in the vicinity of the moving crack also cause non-stationary polarization currents. A possible spectrum of EME has been estimated. The underground fractures produce Very Low (VLF and Extremely Low Frequency (ELF acoustic waves, while the acoustic waves at higher frequencies present high losses and, on the Earth's surface, they are quite small and are not registered. The VLF acoustic wave is subject to nonlinearity under passage through the lithosphere that leads to the generation of higher harmonics and also frequency down-conversion, namely, increasing the ELF acoustic component on the Earth's surface. In turn, a nonlinear propagation of ELF acoustic wave in the atmosphere and the ionosphere leads to emerging the ultra low frequency (ULF acousto-gravity waves in the ionosphere and possible local excitation of plasma waves.

  13. Perturbation measurement of waveguides for acoustic thermometry

    Science.gov (United States)

    Lin, H.; Feng, X. J.; Zhang, J. T.

    2013-09-01

    Acoustic thermometers normally embed small acoustic transducers in the wall bounding a gas-filled cavity resonator. At high temperature, insulators of transducers loss electrical insulation and degrade the signal-to-noise ratio. One essential solution to this technical trouble is to couple sound by acoustic waveguides between resonator and transducers. But waveguide will break the ideal acoustic surface and bring perturbations(Δf+ig) to the ideal resonance frequency. The perturbation model for waveguides was developed based on the first-order acoustic theory in this paper. The frequency shift Δf and half-width change g caused by the position, length and radius of waveguides were analyzed using this model. Six different length of waveguides (52˜1763 mm) were settled on the cylinder resonator and the perturbation (Δf+ig) were measured at T=332 K and p=250˜500 kPa. The experiment results agreed with the theoretical prediction very well.

  14. Integrated immunoassay using tuneable surface acoustic waves and lensfree detection.

    Science.gov (United States)

    Bourquin, Yannyk; Reboud, Julien; Wilson, Rab; Zhang, Yi; Cooper, Jonathan M

    2011-08-21

    The diagnosis of infectious diseases in the Developing World is technologically challenging requiring complex biological assays with a high analytical performance, at minimal cost. By using an opto-acoustic immunoassay technology, integrating components commonly used in mobile phone technologies, including surface acoustic wave (SAW) transducers to provide pressure driven flow and a CMOS camera to enable lensfree detection technique, we demonstrate the potential to produce such an assay. To achieve this, antibody functionalised microparticles were manipulated on a low-cost disposable cartridge using the surface acoustic waves and were then detected optically. Our results show that the biomarker, interferon-γ, used for the diagnosis of diseases such as latent tuberculosis, can be detected at pM concentrations, within a few minutes (giving high sensitivity at a minimal cost). This journal is © The Royal Society of Chemistry 2011

  15. On-line surveillance of lubricants in bearings by means of surface acoustic waves.

    Science.gov (United States)

    Lindner, Gerhard; Schmitt, Martin; Schubert, Josephine; Krempel, Sandro; Faustmann, Hendrik

    2010-01-01

    The acoustic wave propagation in bearings filled with lubricants and driven by pulsed excitation of surface acoustic waves has been investigated with respect to the presence and the distribution of different lubricants. Experimental setups, which are based on the mode conversion between surface acoustic waves and compression waves at the interface between a solid substrate of the bearing and a lubricant are described. The results of preliminary measurements at linear friction bearings, rotation ball bearings and axial cylinder roller bearings are presented.

  16. Fatigue crack propagation of super duplex stainless steel and time-frequency analysis of acoustic emission

    International Nuclear Information System (INIS)

    Lee, Sang Kee; Nam, Ki Woo; Kang, Chang Yong; Do, Jae Yoon

    2000-01-01

    On this study, the fatigue crack propagation of super duplex stainless steel is investigated in conditions of various volume fraction of austenite phase by changing heat treatment temperature. And we analysed acoustic emission signals during the fatigue test by time-frequency analysis methods. As the temperature of heat treatment increased, volume fraction of austenite decreased and coarse grain was obtained. The specimen heat treated at 1200 deg. C had longer fatigue life and slower rate of crack growth. As a result of time-frequency analyze of acoustic emission signals during fatigue test, main frequency was 200∼300 kHz having no correlation with heat treatment and crack length, and 500 kHz was obtained by dimple and separate of inclusion

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

    DEFF Research Database (Denmark)

    2010-01-01

    high intensity and high power acoustic waves (102) by at least one ultrasonic high intensity and high power acoustic wave generator (101 ), wherein the ultrasonic acoustic waves are directed to propagate towards said surface (314) of the object (100) so that a laminar boundary layer (313) of a gas...... or a mixture of gases (500) flow in contact with said solid object (100) is thinned or destructed for at least a part of said surface (314). In this way, the plasma can more efficiently access and influence the surface of the solid object to be treated by the plasma, which speeds the process time up...

  18. Surface acoustic wave propagation in graphene film

    International Nuclear Information System (INIS)

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

    2015-01-01

    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

  19. Masking release with changing fundamental frequency: Electric acoustic stimulation resembles normal hearing subjects.

    Science.gov (United States)

    Auinger, Alice Barbara; Riss, Dominik; Liepins, Rudolfs; Rader, Tobias; Keck, Tilman; Keintzel, Thomas; Kaider, Alexandra; Baumgartner, Wolf-Dieter; Gstoettner, Wolfgang; Arnoldner, Christoph

    2017-07-01

    It has been shown that patients with electric acoustic stimulation (EAS) perform better in noisy environments than patients with a cochlear implant (CI). One reason for this could be the preserved access to acoustic low-frequency cues including the fundamental frequency (F0). Therefore, our primary aim was to investigate whether users of EAS experience a release from masking with increasing F0 difference between target talker and masking talker. The study comprised 29 patients and consisted of three groups of subjects: EAS users, CI users and normal-hearing listeners (NH). All CI and EAS users were implanted with a MED-EL cochlear implant and had at least 12 months of experience with the implant. Speech perception was assessed with the Oldenburg sentence test (OlSa) using one sentence from the test corpus as speech masker. The F0 in this masking sentence was shifted upwards by 4, 8, or 12 semitones. For each of these masker conditions the speech reception threshold (SRT) was assessed by adaptively varying the masker level while presenting the target sentences at a fixed level. A statistically significant improvement in speech perception was found for increasing difference in F0 between target sentence and masker sentence in EAS users (p = 0.038) and in NH listeners (p = 0.003). In CI users (classic CI or EAS users with electrical stimulation only) speech perception was independent from differences in F0 between target and masker. A release from masking with increasing difference in F0 between target and masking speech was only observed in listeners and configurations in which the low-frequency region was presented acoustically. Thus, the speech information contained in the low frequencies seems to be crucial for allowing listeners to separate multiple sources. By combining acoustic and electric information, EAS users even manage tasks as complicated as segregating the audio streams from multiple talkers. Preserving the natural code, like fine-structure cues in

  20. Characterizing riverbed sediment using high-frequency acoustics 1: spectral properties of scattering

    Science.gov (United States)

    Buscombe, Daniel D.; Grams, Paul E.; Kaplinski, Matt A.

    2014-01-01

    Bed-sediment classification using high-frequency hydro-acoustic instruments is challenging when sediments are spatially heterogeneous, which is often the case in rivers. The use of acoustic backscatter to classify sediments is an attractive alternative to analysis of topography because it is potentially sensitive to grain-scale roughness. Here, a new method is presented which uses high-frequency acoustic backscatter from multibeam sonar to classify heterogeneous riverbed sediments by type (sand, gravel,rock) continuously in space and at small spatial resolution. In this, the first of a pair of papers that examine the scattering signatures from a heterogeneous riverbed, methods are presented to construct spatially explicit maps of spectral properties from geo-referenced point clouds of geometrically and radiometrically corrected echoes. Backscatter power spectra are computed to produce scale and amplitude metrics that collectively characterize the length scales of stochastic measures of riverbed scattering, termed ‘stochastic geometries’. Backscatter aggregated over small spatial scales have spectra that obey a power-law. This apparently self-affine behavior could instead arise from morphological- and grain-scale roughnesses over multiple overlapping scales, or riverbed scattering being transitional between Rayleigh and geometric regimes. Relationships exist between stochastic geometries of backscatter and areas of rough and smooth sediments. However, no one parameter can uniquely characterize a particular substrate, nor definitively separate the relative contributions of roughness and acoustic impedance (hardness). Combinations of spectral quantities do, however, have the potential to delineate riverbed sediment patchiness, in a data-driven approach comparing backscatter with bed-sediment observations (which is the subject of part two of this manuscript).

  1. Elastic Characterization of Transparent and Opaque Films, Multilayers and Acoustic Resonators by Surface Brillouin Scattering: A Review

    Directory of Open Access Journals (Sweden)

    Giovanni Carlotti

    2018-01-01

    Full Text Available There is currently a renewed interest in the development of experimental methods to achieve the elastic characterization of thin films, multilayers and acoustic resonators operating in the GHz range of frequencies. The potentialities of surface Brillouin light scattering (surf-BLS for this aim are reviewed in this paper, addressing the various situations that may occur for the different types of structures. In particular, the experimental methodology and the amount of information that can be obtained depending on the transparency or opacity of the film material, as well as on the ratio between the film thickness and the light wavelength, are discussed. A generalization to the case of multilayered samples is also provided, together with an outlook on the capability of the recently developed micro-focused scanning version of the surf-BLS technique, which opens new opportunities for the imaging of the spatial profile of the acoustic field in acoustic resonators and in artificially patterned metamaterials, such as phononic crystals.

  2. Use of acoustic wave travel-time measurements to probe the near-surface layers of the Sun

    Science.gov (United States)

    Jefferies, S. M.; Osaki, Y.; Shibahashi, H.; Duvall, T. L., Jr.; Harvey, J. W.; Pomerantz, M. A.

    1994-01-01

    The variation of solar p-mode travel times with cyclic frequency nu is shown to provide information on both the radial variation of the acoustic potential and the depth of the effective source of the oscillations. Observed travel-time data for waves with frequency lower than the acoustic cutoff frequency for the solar atmosphere (approximately equals 5.5 mHz) are inverted to yield the local acoustic cutoff frequency nu(sub c) as a function of depth in the outer convection zone and lower atmosphere of the Sun. The data for waves with nu greater than 5.5 mHz are used to show that the source of the p-mode oscillations lies approximately 100 km beneath the base of the photosphere. This depth is deeper than that determined using a standard mixing-length calculation.

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

    Science.gov (United States)

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

    2012-07-10

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

  4. Development of a combined surface plasmon resonance/surface acoustic wave device for the characterization of biomolecules

    International Nuclear Information System (INIS)

    Bender, Florian; Tsortos, Achilleas; Papadakis, George; Gizeli, Electra; Roach, Paul; Newton, Michael I; McHale, Glen

    2009-01-01

    It is known that acoustic sensor devices, if operated in liquid phase, are sensitive not just to the mass of the analyte but also to various other parameters, such as size, shape, charge and elastic constants of the analyte as well as bound and viscously entrained water. This can be used to extract valuable information about a biomolecule, particularly if the acoustic device is combined with another sensor element which is sensitive to the mass or amount of analyte only. The latter is true in good approximation for various optical sensor techniques. This work reports on the development of a combined surface plasmon resonance/surface acoustic wave sensor system which is designed for the investigation of biomolecules such as proteins or DNA. Results for the deposition of neutravidin and DNA are reported

  5. Diamond: a material for acoustic devices

    OpenAIRE

    MORTET, Vincent; WILLIAMS, Oliver; HAENEN, Ken

    2008-01-01

    Diamond has been foreseen to replace silicon for high power, high frequency electronic applications or for devices that operates in harsh environments. However, diamond electronic devices are still in the laboratory stage due to the lack of large substrates and the complexity of diamond doping. On another hand, surface acoustic wave filters based on diamond are commercially available. Diamond is especially suited for acoustic applications because of its exceptional mechanical properties. The ...

  6. Ultra-thin smart acoustic metasurface for low-frequency sound insulation

    Science.gov (United States)

    Zhang, Hao; Xiao, Yong; Wen, Jihong; Yu, Dianlong; Wen, Xisen

    2016-04-01

    Insulating low-frequency sound is a conventional challenge due to the high areal mass required by mass law. In this letter, we propose a smart acoustic metasurface consisting of an ultra-thin aluminum foil bonded with piezoelectric resonators. Numerical and experimental results show that the metasurface can break the conventional mass law of sound insulation by 30 dB in the low frequency regime (sound insulation performance is attributed to the infinite effective dynamic mass density produced by the smart resonators. It is also demonstrated that the excellent sound insulation property can be conveniently tuned by simply adjusting the external circuits instead of modifying the structure of the metasurface.

  7. Spontaneous acoustic emission of a corrugated shock wave in the presence of a reflecting surface

    International Nuclear Information System (INIS)

    Wouchuk, J.G.; Lopez Cavada, J.

    2004-01-01

    An analytic model to study perturbation evolution in the space between a corrugated shock and a piston surface is presented. The conditions for stable oscillation patterns are obtained by looking at the poles of the exact Laplace transform. It is seen that besides the standard D'yakov-Kontorovich (DK) mode of oscillation, the shock surface can exhibit an additional finite set of discrete frequencies, due to the interaction with the piston which reflects sound waves from behind. The additional eigenmodes are excited when the shock is launched at t=0 + . The first eigenmode (the DK mode) is always present, if the Hugoniot curve has the correct slope in the V-p plane. However, the additional frequencies could be excited for strong enough shocks. The predictions of the model are verified for particular cases by studying a van der Waals gas, as in the work of Bates and Montgomery [Phys. Fluids 11, 462 (1999); Phys. Rev. Lett. 84, 1180 (2000)]. Only acoustic emission modes are considered

  8. Acoustic lenses

    International Nuclear Information System (INIS)

    Kittmer, C.A.

    1983-03-01

    Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed

  9. Universal Quantum Transducers Based on Surface Acoustic Waves

    NARCIS (Netherlands)

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

    2015-01-01

    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,

  10. Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise

    Directory of Open Access Journals (Sweden)

    Lipiński Marcin

    2016-06-01

    Full Text Available The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

  11. Non-invasive thermal profiling of silicon wafer surface during RTP using acoustic and signal processing techniques

    Science.gov (United States)

    Syed, Ahmed Rashid

    Among the great physical challenges faced by the current front-end semiconductor equipment manufacturers is the accurate and repeatable surface temperature measurement of wafers during various fabrication steps. Close monitoring of temperature is essential in that it ensures desirable device characteristics to be reliably reproduced across various wafer lots. No where is the need to control temperature more pronounced than it is during Rapid Thermal Processing (RTP) which involves temperature ramp rates in excess of 200°C/s. This dissertation presents an elegant and practical approach to solve the wafer surface temperature estimation problem, in context of RTP, by deploying hardware that acquires the necessary data while preserving the integrity and purity of the wafer. In contrast to the widely used wafer-contacting (and hence contaminating) methods, such as bonded thermocouples, or environment sensitive schemes, such as light-pipes and infrared pyrometry, the proposed research explores the concept of utilizing Lamb (acoustic) waves to detect changes in wafer surface temperature, during RTP. Acoustic waves are transmitted to the wafer via an array of quartz rods that normally props the wafer inside an RTP chamber. These waves are generated using piezoelectric transducers affixed to the bases of the quartz rods. The group velocity of Lamb waves traversing the wafer surface undergoes a monotonic decrease with rise in wafer temperature. The correspondence of delay in phase of the received Lamb waves and the ambient temperature, along all direct paths between sending and receiving transducers, yields a psuedo real-time thermal image of the wafer. Although the custom built hardware-setup implements the above "proof-of-concept" scheme by transceiving acoustic signals at a single frequency, the real-world application will seek to enhance the data acquistion. rate (>1000 temperature measurements per seconds) by sending and receiving Lamb waves at multiple frequencies (by

  12. Reverberant acoustic energy in auditoria that comprise systems of coupled rooms

    Science.gov (United States)

    Summers, Jason E.

    2003-11-01

    A frequency-dependent model for reverberant energy in coupled rooms is developed and compared with measurements for a 1:10 scale model and for Bass Hall, Ft. Worth, TX. At high frequencies, prior statistical-acoustics models are improved by geometrical-acoustics corrections for decay within sub-rooms and for energy transfer between sub-rooms. Comparisons of computational geometrical acoustics predictions based on beam-axis tracing with scale model measurements indicate errors resulting from tail-correction assuming constant quadratic growth of reflection density. Using ray tracing in the late part corrects this error. For mid-frequencies, the models are modified to account for wave effects at coupling apertures by including power transmission coefficients. Similarly, statical-acoustics models are improved through more accurate estimates of power transmission measurements. Scale model measurements are in accord with the predicted behavior. The edge-diffraction model is adapted to study transmission through apertures. Multiple-order scattering is theoretically and experimentally shown inaccurate due to neglect of slope diffraction. At low frequencies, perturbation models qualitatively explain scale model measurements. Measurements confirm relation of coupling strength to unperturbed pressure distribution on coupling surfaces. Measurements in Bass Hall exhibit effects of the coupled stage house. High frequency predictions of statistical acoustics and geometrical acoustics models and predictions of coupling apertures all agree with measurements.

  13. Dual fiber Bragg gratings configuration-based fiber acoustic sensor for low-frequency signal detection

    Science.gov (United States)

    Yang, Dong; Wang, Shun; Lu, Ping; Liu, Deming

    2014-11-01

    We propose and fabricate a new type fiber acoustic sensor based on dual fiber Bragg gratings (FBGs) configuration. The acoustic sensor head is constructed by putting the sensing cells enclosed in an aluminum cylinder space built by two Cband FBGs and a titanium diaphragm of 50 um thickness. One end of each FBG is longitudinally adhered to the diaphragm by UV glue. Both of the two FBGs are employed for reflecting light. The dual FBGs play roles not only as signal transmission system but also as sensing component, and they demodulate each other's optical signal mutually during the measurement. Both of the two FBGs are pre-strained and the output optical power experiences fluctuation in a linear relationship along with a variation of axial strain and surrounding acoustic interference. So a precise approach to measure the frequency and sound pressure of the acoustic disturbance is achieved. Experiments are performed and results show that a relatively flat frequency response in a range from 200 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 21 dB is obtained. The maximum sound pressure sensitivity of 11.35mV/Pa is achieved with the Rsquared value of 0.99131 when the sound pressure in the range of 87.7-106.6dB. It has potential applications in low frequency signal detection. Owing to its direct self-demodulation method, the sensing system reveals the advantages of easy to demodulate, good temperature stability and measurement reliability. Besides, performance of the proposed sensor could be improved by optimizing the parameters of the sensor, especially the diaphragm.

  14. Mach-Zehnder interferometric photonic crystal fiber for low acoustic frequency detections

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, Dnyandeo; Rao, Ch. N.; Kale, S. N., E-mail: sangeetakale2004@gmail.com [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411 025, Maharashtra (India); Choubey, Ravi Kant [Department of Applied Physics, Amity Institute of Applied Sciences, Amity University, Noida 201 313 (India)

    2016-01-25

    Low frequency under-water acoustic signal detections are challenging, especially for marine applications. A Mach-Zehnder interferometric hydrophone is demonstrated using polarization-maintaining photonic-crystal-fiber (PM-PCF), spliced between two single-mode-fibers, operated at 1550 nm source. These data are compared with standard hydrophone, single-mode and multimode fiber. The PM-PCF sensor shows the highest response with a power shift (2.32 dBm) and a wavelength shift (392.8 pm) at 200 Hz. High birefringence values and the effect of the imparted acoustic pressure on this fiber, introducing the difference between the fast and slow axis changes, owing to the phase change in the propagation waves, demonstrate the strain-optic properties of the sensor.

  15. Frequency tunable surface magneto elastic waves

    NARCIS (Netherlands)

    Janusonis, J.; Chang, C. L.; van Loosdrecht, P. H. M.; Tobey, R. I.

    2015-01-01

    We use the transient grating technique to generate narrow-band, widely tunable, in-plane surface magnetoelastic waves in a nickel film. We monitor both the structural deformation of the acoustic wave and the accompanying magnetic precession and witness their intimate coupling in the time domain.

  16. Investigation of air-assisted sprays submitted to high frequency transverse acoustic fields: Droplet clustering

    Science.gov (United States)

    Ficuciello, A.; Blaisot, J. B.; Richard, C.; Baillot, F.

    2017-06-01

    An experimental investigation of the effects of a high amplitude transverse acoustic field on coaxial jets is presented in this paper. Water and air are used as working fluids at ambient pressure. The coaxial injectors are placed on the top of a semi-open resonant cavity where the acoustic pressure fluctuations of the standing wave can reach a maximum peak-to-peak amplitude of 12 kPa at the forcing frequency of 1 kHz. Several test conditions are considered in order to quantify the influence of injection conditions, acoustic field amplitude, and injector position with respect to the standing wave acoustic field. A high speed back-light visualization technique is used to characterize the jet response. Image processing is used to obtain valuable information about the jet behavior. It is shown that the acoustic field drastically affects the atomization process for all atomization regimes. The position of the injector in the acoustic field determines the jet response, and a droplet-clustering phenomenon is highlighted in multi-point injection conditions and quantified by determining discrete droplet location distributions. A theoretical model based on nonlinear acoustics related to the spatial distribution of the radiation pressure exerted on an object explains the behavior observed.

  17. Spatial Release From Masking in Simulated Cochlear Implant Users With and Without Access to Low-Frequency Acoustic Hearing

    Directory of Open Access Journals (Sweden)

    Ben Williges

    2015-12-01

    Full Text Available For normal-hearing listeners, speech intelligibility improves if speech and noise are spatially separated. While this spatial release from masking has already been quantified in normal-hearing listeners in many studies, it is less clear how spatial release from masking changes in cochlear implant listeners with and without access to low-frequency acoustic hearing. Spatial release from masking depends on differences in access to speech cues due to hearing status and hearing device. To investigate the influence of these factors on speech intelligibility, the present study measured speech reception thresholds in spatially separated speech and noise for 10 different listener types. A vocoder was used to simulate cochlear implant processing and low-frequency filtering was used to simulate residual low-frequency hearing. These forms of processing were combined to simulate cochlear implant listening, listening based on low-frequency residual hearing, and combinations thereof. Simulated cochlear implant users with additional low-frequency acoustic hearing showed better speech intelligibility in noise than simulated cochlear implant users without acoustic hearing and had access to more spatial speech cues (e.g., higher binaural squelch. Cochlear implant listener types showed higher spatial release from masking with bilateral access to low-frequency acoustic hearing than without. A binaural speech intelligibility model with normal binaural processing showed overall good agreement with measured speech reception thresholds, spatial release from masking, and spatial speech cues. This indicates that differences in speech cues available to listener types are sufficient to explain the changes of spatial release from masking across these simulated listener types.

  18. Wind Turbine Acoustic Investigation: Infrasound and Low-Frequency Noise--A Case Study

    Science.gov (United States)

    Ambrose, Stephen E.; Rand, Robert W.; Krogh, Carmen M. E.

    2012-01-01

    Wind turbines produce sound that is capable of disturbing local residents and is reported to cause annoyance, sleep disturbance, and other health-related impacts. An acoustical study was conducted to investigate the presence of infrasonic and low-frequency noise emissions from wind turbines located in Falmouth, Massachusetts, USA. During the…

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

    Directory of Open Access Journals (Sweden)

    Siegfried Hohmann

    2015-05-01

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

  20. Physically based method for measuring suspended-sediment concentration and grain size using multi-frequency arrays of acoustic-doppler profilers

    Science.gov (United States)

    Topping, David J.; Wright, Scott A.; Griffiths, Ronald; Dean, David

    2014-01-01

    As the result of a 12-year program of sediment-transport research and field testing on the Colorado River (6 stations in UT and AZ), Yampa River (2 stations in CO), Little Snake River (1 station in CO), Green River (1 station in CO and 2 stations in UT), and Rio Grande (2 stations in TX), we have developed a physically based method for measuring suspended-sediment concentration and grain size at 15-minute intervals using multifrequency arrays of acoustic-Doppler profilers. This multi-frequency method is able to achieve much higher accuracies than single-frequency acoustic methods because it allows removal of the influence of changes in grain size on acoustic backscatter. The method proceeds as follows. (1) Acoustic attenuation at each frequency is related to the concentration of silt and clay with a known grain-size distribution in a river cross section using physical samples and theory. (2) The combination of acoustic backscatter and attenuation at each frequency is uniquely related to the concentration of sand (with a known reference grain-size distribution) and the concentration of silt and clay (with a known reference grain-size distribution) in a river cross section using physical samples and theory. (3) Comparison of the suspended-sand concentrations measured at each frequency using this approach then allows theory-based calculation of the median grain size of the suspended sand and final correction of the suspended-sand concentration to compensate for the influence of changing grain size on backscatter. Although this method of measuring suspended-sediment concentration is somewhat less accurate than using conventional samplers in either the EDI or EWI methods, it is much more accurate than estimating suspended-sediment concentrations using calibrated pump measurements or single-frequency acoustics. Though the EDI and EWI methods provide the most accurate measurements of suspended-sediment concentration, these measurements are labor-intensive, expensive, and

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

    DEFF Research Database (Denmark)

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

    can be minimized either by distribution of reflecting material in a design domain along the ceiling or by distribution of absorbing and reflecting material along all the walls for both 2D and 3D problems. It is also shown how the method can be used to design sound barriers. The main part...... in order to optimize more complicated SAW structures such as acoustic horns which focus the SAWs to a small area. [1] M. P. Bendsøe, O. Sigmund, “Topology optimization, theory, methods and applications”, Springer Verlag Berlin Heidelberg New York, 2nd edition, (2003). ISBN 3-540-42992-1. [2] J. S. Jensen......, Berlin, (2000). ISBN 3-540-67232-X. [5] M. M. de Lima Jr and P. V. Santos, “Modulation of photonic structures by surface acoustic waves”, Rep. Prog. Phys., 68 1639-1701 (2005)...

  2. Combined failure acoustical diagnosis based on improved frequency domain blind deconvolution

    International Nuclear Information System (INIS)

    Pan, Nan; Wu, Xing; Chi, YiLin; Liu, Xiaoqin; Liu, Chang

    2012-01-01

    According to gear box combined failure extraction in complex sound field, an acoustic fault detection method based on improved frequency domain blind deconvolution was proposed. Follow the frequency-domain blind deconvolution flow, the morphological filtering was firstly used to extract modulation features embedded in the observed signals, then the CFPA algorithm was employed to do complex-domain blind separation, finally the J-Divergence of spectrum was employed as distance measure to resolve the permutation. Experiments using real machine sound signals was carried out. The result demonstrate this algorithm can be efficiently applied to gear box combined failure detection in practice.

  3. High-frequency acoustic spectrum analyzer based on polymer integrated optics

    Science.gov (United States)

    Yacoubian, Araz

    This dissertation presents an acoustic spectrum analyzer based on nonlinear polymer-integrated optics. The device is used in a scanning heterodyne geometry by zero biasing a Michelson interferometer. It is capable of detecting vibrations from DC to the GHz range. Initial low frequency experiments show that the device is an effective tool for analyzing an acoustic spectrum even in noisy environments. Three generations of integrated sensors are presented, starting with a very lossy (86 dB total insertion loss) initial device that detects vibrations as low as λ/10, and second and third generation improvements with a final device of 44 dB total insertion loss. The sensor was further tested for detecting a pulsed laser-excited vibration and resonances due to the structure of the sample. The data are compared to the acoustic spectrum measured using a low loss passive fiber interferometer detection scheme which utilizes a high speed detector. The peaks present in the passive detection scheme are clearly visible with our sensor data, which have a lower noise floor. Hybrid integration of GHz electronics is also investigated in this dissertation. A voltage controlled oscillator (VCO) is integrated on a polymer device using a new approach. The VCO is shown to operate as specified by the manufacturer, and the RF signal is efficiently launched onto the micro-strip line used for EO modulation. In the future this technology can be used in conjunction with the presented sensor to produce a fully integrated device containing high frequency drive electronics controlled by low DC voltage. Issues related to device fabrication, loss analysis, RF power delivery to drive circuitry, efficient poling of large area samples, and optimizing poling conditions are also discussed throughout the text.

  4. Charge pumping in InAs nanowires by surface acoustic waves

    NARCIS (Netherlands)

    Roddaro, Stefano; Strambini, Elia; Romeo, Lorenzo; Piazza, Vincenzo; Nilsson, Kristian; Samuelson, Lars; Beltram, Fabio

    2010-01-01

    We investigate the interaction between surface acoustic waves on a piezoelectric LiNbO3 substrate and charge carriers in InAs nanowire transistors. Interdigital transducers are used to excite electromechanical waves on the chip surface and their influence on the transport in the nanowire devices is

  5. Carrier frequency offset estimation for an acoustic-electric channel using 16 QAM modulation

    Science.gov (United States)

    Cunningham, Michael T.; Anderson, Leonard A.; Wilt, Kyle R.; Chakraborty, Soumya; Saulnier, Gary J.; Scarton, Henry A.

    2016-05-01

    Acoustic-electric channels can be used to send data through metallic barriers, enabling communications where electromagnetic signals are ineffective. This paper considers an acoustic-electric channel that is formed by mounting piezoelectric transducers on metallic barriers that are separated by a thin water layer. The transducers are coupled to the barriers using epoxy and the barriers are positioned to axially-align the PZTs, maximizing energy transfer efficiency. The electrical signals are converted by the transmitting transducers into acoustic waves, which propagate through the elastic walls and water medium to the receiving transducers. The reverberation of the acoustic signals in these channels can produce multipath distortion with a significant delay spread that introduces inter-symbol interference (ISI) into the received signal. While the multipath effects can be severe, the channel does not change rapidly which makes equalization easier. Here we implement a 16-QAM system on this channel, including a method for obtaining accurate carrier frequency offset (CFO) estimates in the presence of the quasi-static multipath propagation. A raised-power approach is considered but found to suffer from excessive data noise resulting from the ISI. An alternative approach that utilizes a pilot tone burst at the start of a data packet is used for CFO estimation and found to be effective. The autocorrelation method is used to estimate the frequency of the received burst. A real-time prototype of the 16 QAM system that uses a Texas Instruments MSP430 microcontroller-based transmitter and a personal computer-based receiver is presented along with performance results.

  6. Theoretical vibro-acoustic modeling of acoustic noise transmission through aircraft windows

    Science.gov (United States)

    Aloufi, Badr; Behdinan, Kamran; Zu, Jean

    2016-06-01

    In this paper, a fully vibro-acoustic model for sound transmission across a multi-pane aircraft window is developed. The proposed model is efficiently applied for a set of window models to perform extensive theoretical parametric studies. The studied window configurations generally simulate the passenger window designs of modern aircraft classes which have an exterior multi-Plexiglas pane, an interior single acrylic glass pane and a dimmable glass ("smart" glass), all separated by thin air cavities. The sound transmission loss (STL) characteristics of three different models, triple-, quadruple- and quintuple-paned windows identical in size and surface density, are analyzed for improving the acoustic insulation performances. Typical results describing the influence of several system parameters, such as the thicknesses, number and spacing of the window panes, on the transmission loss are then investigated. In addition, a comparison study is carried out to evaluate the acoustic reduction capability of each window model. The STL results show that the higher frequencies sound transmission loss performance can be improved by increasing the number of window panels, however, the low frequency performance is decreased, particularly at the mass-spring resonances.

  7. Grating-assisted surface acoustic wave directional couplers

    Science.gov (United States)

    Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

    1991-07-01

    Physical properties of novel grating-assisted Y directional couplers are examined using the coupled-mode theory. A general formalism for the analysis of the lateral perturbed directional coupler properties is presented. Explicit expressions for waveguide key parameters such as coupling length, grating period, and other structural characterizations, are obtained. The influence of other physical properties such as time and frequency response or cutoff conditions are also analyzed. A plane grating-assisted directional coupler is presented and examined as a basic component in the integrated acoustic technology.

  8. Dynamic Leidenfrost temperature on micro-textured surfaces: Acoustic wave absorption into thin vapor layer

    Science.gov (United States)

    Jerng, Dong Wook; Kim, Dong Eok

    2018-01-01

    The dynamic Leidenfrost phenomenon is governed by three types of pressure potentials induced via vapor hydrodynamics, liquid dynamic pressure, and the water hammer effect resulting from the generation of acoustic waves at the liquid-vapor interface. The prediction of the Leidenfrost temperature for a dynamic droplet needs quantitative evaluation and definition for each of the pressure fields. In particular, the textures on a heated surface can significantly affect the vapor hydrodynamics and the water hammer pressure. We present a quantitative model for evaluating the water hammer pressure on micro-textured surfaces taking into account the absorption of acoustic waves into the thin vapor layer. The model demonstrates that the strength of the acoustic flow into the liquid droplet, which directly contributes to the water hammer pressure, depends on the magnitude of the acoustic resistance (impedance) in the droplet and the vapor region. In consequence, the micro-textures of the surface and the increased spacing between them reduce the water hammer coefficient ( kh ) defined as the ratio of the acoustic flow into the droplet to total generated flow. Aided by numerical calculations that solve the laminar Navier-Stokes equation for the vapor flow, we also predict the dynamic Leidenfrost temperature on a micro-textured surface with reliable accuracy consistent with the experimental data.

  9. Head Injury and Intracranial Pressure Monitor Using Ultrasonic and Low-Frequency Acoustic (ULFA) Detection

    National Research Council Canada - National Science Library

    Vo-Dinh, Tuan

    2001-01-01

    The main objective of this research project is the development of a non-invasive method and instrument for head injury detection and monitoring using a new approach based on ultrasonic and low-frequency acoustic (ULFA...

  10. Bilinear Time-frequency Analysis for Lamb Wave Signal Detected by Electromagnetic Acoustic Transducer

    Science.gov (United States)

    Sun, Wenxiu; Liu, Guoqiang; Xia, Hui; Xia, Zhengwu

    2018-03-01

    Accurate acquisition of the detection signal travel time plays a very important role in cross-hole tomography. The experimental platform of aluminum plate under the perpendicular magnetic field is established and the bilinear time-frequency analysis methods, Wigner-Ville Distribution (WVD) and the pseudo-Wigner-Ville distribution (PWVD), are applied to analyse the Lamb wave signals detected by electromagnetic acoustic transducer (EMAT). By extracting the same frequency component of the time-frequency spectrum as the excitation frequency, the travel time information can be obtained. In comparison with traditional linear time-frequency analysis method such as short-time Fourier transform (STFT), the bilinear time-frequency analysis method PWVD is more appropriate in extracting travel time and recognizing patterns of Lamb wave.

  11. Excitation of hypersonic acoustic waves in diamond-based piezoelectric layered structure on the microwave frequencies up to 20GHz.

    Science.gov (United States)

    Sorokin, B P; Kvashnin, G M; Novoselov, A S; Bormashov, V S; Golovanov, A V; Burkov, S I; Blank, V D

    2017-07-01

    First ultrahigh frequency (UHF) investigation of quality factor Q for the piezoelectric layered structure «Al/(001)AlN/Mo/(100) diamond» has been executed in a broad frequency band from 1 up to 20GHz. The record-breaking Q·f quality parameter up to 2.7·10 14 Hz has been obtained close to 20GHz. Frequency dependence of the form factor m correlated with quality factor has been analyzed by means of computer simulation, and non-monotonic frequency dependence can be explained by proper features of thin-film piezoelectric transducer (TFPT). Excluding the minimal Q magnitudes measured at the frequency points associated with minimal TFPT effectiveness, one can prove a rule of Qf∼f observed for diamond on the frequencies above 1GHz and defined by Landau-Rumer's acoustic attenuation mechanism. Synthetic IIa-type diamond single crystal as a substrate material for High-overtone Bulk Acoustic Resonator (HBAR) possesses some excellent acoustic properties in a wide microwave band and can be successfully applied for design of acoustoelectronic devices, especially the ones operating at a far UHF band. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Directory of Open Access Journals (Sweden)

    N. I. Polzikova

    2016-05-01

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

  13. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Energy Technology Data Exchange (ETDEWEB)

    Polzikova, N. I., E-mail: polz@cplire.ru; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P. [Kotel’nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences, Mokhovaya 11, building 7, Moscow, 125009 (Russian Federation)

    2016-05-15

    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.

  14. Acoustic-wave sensor for ambient monitoring of a photoresist-stripping agent

    Science.gov (United States)

    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. Surface Acoustic WaveAmmonia Sensors Based on ST-cut Quartz under Periodic Al Structure

    Directory of Open Access Journals (Sweden)

    Ming-Yau Su

    2009-02-01

    Full Text Available Surface acoustic wave (SAW devices are key components for sensing applications. SAW propagation under a periodic grating was investigated in this work. The theoretical method used here is the space harmonic method. We also applied the results of SAW propagation studied in this work to design a two-port resonator with an Al grating on ST-cut quartz. The measured frequency responses of the resonator were similar to the simulation ones. Then, the chemical interface of polyaniline/WO3 composites was coated on the SAW sensor for ammonia detection. The SAW sensor responded to ammonia gas and could be regenerated using dry nitrogen.

  16. Acoustic cloaking and transformation acoustics

    International Nuclear Information System (INIS)

    Chen Huanyang; Chan, C T

    2010-01-01

    In this review, we give a brief introduction to the application of the new technique of transformation acoustics, which draws on a correspondence between coordinate transformation and material properties. The technique is formulated for both acoustic waves and linear liquid surface waves. Some interesting conceptual devices can be designed for manipulating acoustic waves. For example, we can design acoustic cloaks that make an object invisible to acoustic waves, and the cloak can either encompass or lie outside the object to be concealed. Transformation acoustics, as an analog of transformation optics, can go beyond invisibility cloaking. As an illustration for manipulating linear liquid surface waves, we show that a liquid wave rotator can be designed and fabricated to rotate the wave front. The acoustic transformation media require acoustic materials which are anisotropic and inhomogeneous. Such materials are difficult to find in nature. However, composite materials with embedded sub-wavelength resonators can in principle be made and such 'acoustic metamaterials' can exhibit nearly arbitrary values of effective density and modulus tensors to satisfy the demanding material requirements in transformation acoustics. We introduce resonant sonic materials and Helmholtz resonators as examples of acoustic metamaterials that exhibit resonant behaviour in effective density and effective modulus. (topical review)

  17. CAMEX-3 JPL SURFACE ACOUSTIC WAVE (SAW) HYGROMETER V1

    Data.gov (United States)

    National Aeronautics and Space Administration — This CAMEX-3 Jet Propulsion Laboratory (JPL) Surface Acoustic Wave (SAW) Hygrometer dataset consists of dewpoint timeline measurements acquired during each DC-8...

  18. An Electronic-Nose Sensor Node Based on a Polymer-Coated Surface Acoustic Wave Array for Wireless Sensor Network Applications

    Science.gov (United States)

    Tang, Kea-Tiong; Li, Cheng-Han; Chiu, Shih-Wen

    2011-01-01

    This study developed an electronic-nose sensor node based on a polymer-coated surface acoustic wave (SAW) sensor array. The sensor node comprised an SAW sensor array, a frequency readout circuit, and an Octopus II wireless module. The sensor array was fabricated on a large K2 128° YX LiNbO3 sensing substrate. On the surface of this substrate, an interdigital transducer (IDT) was produced with a Cr/Au film as its metallic structure. A mixed-mode frequency readout application specific integrated circuit (ASIC) was fabricated using a TSMC 0.18 μm process. The ASIC output was connected to a wireless module to transmit sensor data to a base station for data storage and analysis. This sensor node is applicable for wireless sensor network (WSN) applications. PMID:22163865

  19. An electronic-nose sensor node based on a polymer-coated surface acoustic wave array for wireless sensor network applications.

    Science.gov (United States)

    Tang, Kea-Tiong; Li, Cheng-Han; Chiu, Shih-Wen

    2011-01-01

    This study developed an electronic-nose sensor node based on a polymer-coated surface acoustic wave (SAW) sensor array. The sensor node comprised an SAW sensor array, a frequency readout circuit, and an Octopus II wireless module. The sensor array was fabricated on a large K(2) 128° YX LiNbO3 sensing substrate. On the surface of this substrate, an interdigital transducer (IDT) was produced with a Cr/Au film as its metallic structure. A mixed-mode frequency readout application specific integrated circuit (ASIC) was fabricated using a TSMC 0.18 μm process. The ASIC output was connected to a wireless module to transmit sensor data to a base station for data storage and analysis. This sensor node is applicable for wireless sensor network (WSN) applications.

  20. An Electronic-Nose Sensor Node Based on a Polymer-Coated Surface Acoustic Wave Array for Wireless Sensor Network Applications

    Directory of Open Access Journals (Sweden)

    Kea-Tiong Tang

    2011-04-01

    Full Text Available This study developed an electronic-nose sensor node based on a polymer-coated surface acoustic wave (SAW sensor array. The sensor node comprised an SAW sensor array, a frequency readout circuit, and an Octopus II wireless module. The sensor array was fabricated on a large K2 128° YX LiNbO3 sensing substrate. On the surface of this substrate, an interdigital transducer (IDT was produced with a Cr/Au film as its metallic structure. A mixed-mode frequency readout application specific integrated circuit (ASIC was fabricated using a TSMC 0.18 μm process. The ASIC output was connected to a wireless module to transmit sensor data to a base station for data storage and analysis. This sensor node is applicable for wireless sensor network (WSN applications.

  1. Low-frequency acoustic atomization with oscillatory flow around micropillars in a microfluidic device

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Yin Nee, E-mail: mailccheung@gmail.com, E-mail: mtnwong@ntu.edu.sg; Wong, Teck Neng, E-mail: mailccheung@gmail.com, E-mail: mtnwong@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore); Nguyen, Nam Trung, E-mail: nam-trung.nguyen@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Brisbane QLD 4111 (Australia)

    2014-10-06

    This letter reports a low frequency acoustic atomization technique with oscillatory extensional flow around micropillars. Large droplets passing through two micropillars are elongated. Small droplets are then produced through the pinch-off process at the spindle-shape ends. As the actuation frequency increases, the droplet size decreases with increasing monodispersity. This method is suitable for in-situ mass production of fine droplets in a multi-phase environment without external pumping. Small particles encapsulation was demonstrated with the current technique.

  2. Frequency Response of the Sample Vibration Mode in Scanning Probe Acoustic Microscope

    International Nuclear Information System (INIS)

    Ya-Jun, Zhao; Qian, Cheng; Meng-Lu, Qian

    2010-01-01

    Based on the interaction mechanism between tip and sample in the contact mode of a scanning probe acoustic microscope (SPAM), an active mass of the sample is introduced in the mass-spring model. The tip motion and frequency response of the sample vibration mode in the SPAM are calculated by the Lagrange equation with dissipation function. For the silicon tip and glass assemblage in the SPAM the frequency response is simulated and it is in agreement with the experimental result. The living myoblast cells on the glass slide are imaged at resonance frequencies of the SPAM system, which are 20kHz, 30kHz and 120kHz. It is shown that good contrast of SPAM images could be obtained when the system is operated at the resonance frequencies of the system in high and low-frequency regions

  3. Acoustic characterization of a CANDU primary heat transport pump at the blade-passing frequency

    International Nuclear Information System (INIS)

    Rzentkowski, G.; Zbroja, S.

    2000-01-01

    In this paper, we examine the acoustics of a single-stage, double-volute CANDU heat transport pump based on a full-scale experimental investigation. We estimate the strength of source variables (acoustic pressure and velocity) and establish the pump characteristics as an acoustic source at the blade-passing frequency. We conduct this analysis by first assessing the resonance effects in the test loop, and then decomposing the measured signal into the components associated with pump action and loop acoustics with the use of a simple pump model. The pump model is based on a linear superposition of pressure wave transmission and excitation. The results of this analysis indicate that the pump source variables are nearly free of acoustic resonance effects in the test loop. The source pressure and velocity are each estimated at approximately 10 kPa (zero-to-peak). The results also indicate that the pump may act as both a pressure and a velocity source. At the loop resonance, the pump acoustic behavior is exclusively governed by the pressure term. This observation leads to the conclusion that the maximum amplification of pressure pulsations in a reactor heat transport system may be predicted by modeling the pump as a pressure source. (orig.)

  4. Sustainable Acoustic Metasurfaces for Sound Control

    Directory of Open Access Journals (Sweden)

    Paola Gori

    2016-01-01

    Full Text Available Sound attenuation with conventional acoustic materials is subject to the mass law and requires massive and bulky structures at low frequencies. A possible alternative solution is provided by the use of metamaterials, which are artificial materials properly engineered to obtain properties and characteristics that it is not possible to find in natural materials. Theory and applications of metamaterials, already consolidated in electromagnetism, can be extended to acoustics; in particular, they can be applied to improve the properties of acoustical panels. The design of acoustic metasurfaces that could effectively control transmitted sound in unconventional ways appears a significant subject to be investigated, given its wide-ranging possible applications. In this contribution, we investigate the application of a metasurface-inspired technique to achieve the acoustical insulation of an environment. The designed surface has subwavelength thickness and structuring and could be realized with cheap, lightweight and sustainable materials. We present a few examples of such structures and analyze their acoustical behavior by means of full-wave simulations.

  5. Swept frequency acoustic interferometry technique for chemical weapons verification and monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, D.N.; Anthony, B.W.; Lizon, D.C.

    1995-03-01

    Nondestructive evaluation (NDE) techniques are important for rapid on-site verification and monitoring of chemical munitions, such as artillery shells and bulk containers. Present NDE techniques provide only limited characterizations of such munitions. This paper describes the development of a novel noninvasive technique, swept-frequency acoustic interferometry (SFAI), that significantly enhances the capability of munitions characterizations. The SFAI technique allows very accurate and simultaneous determination of sound velocity and attenuation of chemical agents over a large frequency range inside artillery shells, in addition to determining agent density. The frequency-dependent sound velocity and attenuation can, in principle, provide molecular relaxation properties of the chemical agent. The same instrument also enables a direct fill-level measurement in bulk containers. Industrial and other applications of this general-purpose technique are also discussed.

  6. Comparison of spatial frequency domain features for the detection of side attack explosive ballistics in synthetic aperture acoustics

    Science.gov (United States)

    Dowdy, Josh; Anderson, Derek T.; Luke, Robert H.; Ball, John E.; Keller, James M.; Havens, Timothy C.

    2016-05-01

    Explosive hazards in current and former conflict zones are a threat to both military and civilian personnel. As a result, much effort has been dedicated to identifying automated algorithms and systems to detect these threats. However, robust detection is complicated due to factors like the varied composition and anatomy of such hazards. In order to solve this challenge, a number of platforms (vehicle-based, handheld, etc.) and sensors (infrared, ground penetrating radar, acoustics, etc.) are being explored. In this article, we investigate the detection of side attack explosive ballistics via a vehicle-mounted acoustic sensor. In particular, we explore three acoustic features, one in the time domain and two on synthetic aperture acoustic (SAA) beamformed imagery. The idea is to exploit the varying acoustic frequency profile of a target due to its unique geometry and material composition with respect to different viewing angles. The first two features build their angle specific frequency information using a highly constrained subset of the signal data and the last feature builds its frequency profile using all available signal data for a given region of interest (centered on the candidate target location). Performance is assessed in the context of receiver operating characteristic (ROC) curves on cross-validation experiments for data collected at a U.S. Army test site on different days with multiple target types and clutter. Our preliminary results are encouraging and indicate that the top performing feature is the unrolled two dimensional discrete Fourier transform (DFT) of SAA beamformed imagery.

  7. Passive Wireless Hydrogen Sensors Using Orthogonal Frequency Coded Acoustic Wave Devices, Phase I

    Data.gov (United States)

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

  8. Surface Wave Focusing and Acoustic Communications in the Surf Zone

    National Research Council Canada - National Science Library

    Preisig, James

    2004-01-01

    The forward scattering of acoustic signals off of shoaling surface gravity waves in the surf zone results in a time-varying channel impulse response that is characterized by intense, rapidly fluctuating arrivals...

  9. Impulse excitation scanning acoustic microscopy for local quantification of Rayleigh surface wave velocity using B-scan analysis

    Science.gov (United States)

    Cherry, M.; Dierken, J.; Boehnlein, T.; Pilchak, A.; Sathish, S.; Grandhi, R.

    2018-01-01

    A new technique for performing quantitative scanning acoustic microscopy imaging of Rayleigh surface wave (RSW) velocity was developed based on b-scan processing. In this technique, the focused acoustic beam is moved through many defocus distances over the sample and excited with an impulse excitation, and advanced algorithms based on frequency filtering and the Hilbert transform are used to post-process the b-scans to estimate the Rayleigh surface wave velocity. The new method was used to estimate the RSW velocity on an optically flat E6 glass sample, and the velocity was measured at ±2 m/s and the scanning time per point was on the order of 1.0 s, which are both improvement from the previous two-point defocus method. The new method was also applied to the analysis of two titanium samples, and the velocity was estimated with very low standard deviation in certain large grains on the sample. A new behavior was observed with the b-scan analysis technique where the amplitude of the surface wave decayed dramatically on certain crystallographic orientations. The new technique was also compared with previous results, and the new technique has been found to be much more reliable and to have higher contrast than previously possible with impulse excitation.

  10. Surface Acoustic Waves to Drive Plant Transpiration.

    Science.gov (United States)

    Gomez, Eliot F; Berggren, Magnus; Simon, Daniel T

    2017-03-31

    Emerging fields of research in electronic plants (e-plants) and agro-nanotechnology seek to create more advanced control of plants and their products. Electronic/nanotechnology plant systems strive to seamlessly monitor, harvest, or deliver chemical signals to sense or regulate plant physiology in a controlled manner. Since the plant vascular system (xylem/phloem) is the primary pathway used to transport water, nutrients, and chemical signals-as well as the primary vehicle for current e-plant and phtyo-nanotechnology work-we seek to directly control fluid transport in plants using external energy. Surface acoustic waves generated from piezoelectric substrates were directly coupled into rose leaves, thereby causing water to rapidly evaporate in a highly localized manner only at the site in contact with the actuator. From fluorescent imaging, we find that the technique reliably delivers up to 6x more water/solute to the site actuated by acoustic energy as compared to normal plant transpiration rates and 2x more than heat-assisted evaporation. The technique of increasing natural plant transpiration through acoustic energy could be used to deliver biomolecules, agrochemicals, or future electronic materials at high spatiotemporal resolution to targeted areas in the plant; providing better interaction with plant physiology or to realize more sophisticated cyborg systems.

  11. Absorption of longitudinal high-frequency acoustic waves in Ysub(3-x)Lusub(x)Alsub(5)Osub(12) crystals

    International Nuclear Information System (INIS)

    Gulyaev, Yu.V.; Ivanov, S.N.; Kozorezov, A.G.; Kotelyanskij, I.M.; Medved', V.V.; Akhmetov, S.F.; Davydchenko, A.G.

    1983-01-01

    Absorption of longitudinal high frequency acoustic waves in Ysub(3-x)Lusub(x)Alsub(5)Osub(12) l0<=x<=3) crystals is investigated theoretically and experimentally at temperatures T<80 K in the case when the absorption in a pure crystal is due to three-phonon processes. It is shown that the absorption of acoustic waves depends pronouncedly on the impurity concentration. The frequency dependence of sound absorption at low temperatures is found to possess a number of peculiarities. The form of the dependence qualitatively corresponds to that predicted theoretically

  12. Enhanced Sensitivity of Surface Acoustic Wave-Based Rate Sensors Incorporating Metallic Dot Arrays

    Directory of Open Access Journals (Sweden)

    Wen Wang

    2014-02-01

    Full Text Available A new surface acoustic wave (SAW-based rate sensor pattern incorporating metallic dot arrays was developed in this paper. Two parallel SAW delay lines with a reverse direction and an operation frequency of 80 MHz on a same X-112°Y LiTaO3 wafer are fabricated as the feedback of two SAW oscillators, and mixed oscillation frequency was used to characterize the external rotation. To enhance the Coriolis force effect acting on the SAW propagation, a copper (Cu dot array was deposited along the SAW propagation path of the SAW devices. The approach of partial-wave analysis in layered media was referred to analyze the response mechanisms of the SAW based rate sensor, resulting in determination of the optimal design parameters. To improve the frequency stability of the oscillator, the single phase unidirectional transducers (SPUDTs and combed transducer were used to form the SAW device to minimize the insertion loss and accomplish the single mode selection, respectively. Excellent long-term (measured in hours frequency stability of 0.1 ppm/h was obtained. Using the rate table with high precision, the performance of the developed SAW rate sensor was evaluated experimentally; satisfactory detection sensitivity (16.7 Hz∙deg∙s−1 and good linearity were observed.

  13. Novel types of surface acoustic wave microreflectors - Performance analysis and simulations

    Science.gov (United States)

    Golan, G.; Griffel, G.; Seidman, A.; Croitoru, N.

    1990-06-01

    Surface acoustic waves for micrograting reflectors have been characterized. Based on the perturbation theory, eight different types of structures on an acoustic waveguide were analyzed. Results of simulations of all eight types of corrugation structures were evaluated in order to find the least leaky waveguide, the most efficient reflector (with minimum necessary perturbations), and the optimal mode shape for improved performances. General design curves are presented in order to illustrate the behavior of the incident and reflected waves under a variety of structural conditions. Analytic expressions for the calculations of the mode amplitude and mode shape, and for general acoustic corrugations are derived and then the simulations results are presented.

  14. Control of cavity acoustics by surface waviness in landing configurations

    CSIR Research Space (South Africa)

    Dala, L

    2014-08-01

    Full Text Available ): 2321-3051 INTERNATIONAL JOURNAL OF RESEARCH IN AERONAUTICAL AND MECHANICAL ENGINEERING Control of Cavity Acoustics by Surface Waviness In Landing Configurations Laurent Dala CSIR, DPSS/Aeronautics Systems, Pretoria 0001, South Africa...

  15. Silence on Shangri-La: Attenuation of Huygens acoustic signals suggests surface volatiles

    Science.gov (United States)

    Lorenz, Ralph D.; Leese, Mark R.; Hathi, Brijen; Zarnecki, John C.; Hagermann, Axel; Rosenberg, Phil; Towner, Martin C.; Garry, James; Svedhem, Håkan

    2014-01-01

    Objective. Characterize and understand acoustic instrument performance on the surface of Titan. Methods. The Huygens probe measured the speed of sound in Titan's atmosphere with a 1 MHz pulse time-of-flight transducer pair near the bottom of the vehicle. We examine the fraction of pulses correctly received as a function of time. Results. This system returned good data from about 11 km altitude, where the atmosphere became thick enough to effectively transmit the sound, down to the surface just before landing: these data have been analyzed previously. After an initial transient at landing, the instrument operated nominally for about 10 min, recording pulses much as during descent. The fraction of pulses detected then declined and the transmitted sound ceased to be detected altogether, despite no indication of instrument or probe configuration changes. Conclusions. The most likely explanation appears to be absorption of the signal by polyatomic gases with relaxation losses at the instrument frequency, such as ethane, acetylene and carbon dioxide. These vapors, detected independently by the GCMS instrument, were evolved from the surface material by the warmth leaking from the probe, and confirm the nature of the surface materials as 'damp' with a cocktail of volatile compounds. Some suggestions for future missions are considered. Practice implications. None.

  16. Wireless Multiplexed Surface Acoustic Wave Sensors Project

    Science.gov (United States)

    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).

  17. Laser-induced acoustic imaging of underground objects

    Science.gov (United States)

    Li, Wen; DiMarzio, Charles A.; McKnight, Stephen W.; Sauermann, Gerhard O.; Miller, Eric L.

    1999-02-01

    This paper introduces a new demining technique based on the photo-acoustic interaction, together with results from photo- acoustic experiments. We have buried different types of targets (metal, rubber and plastic) in different media (sand, soil and water) and imaged them by measuring reflection of acoustic waves generated by irradiation with a CO2 laser. Research has been focused on the signal acquisition and signal processing. A deconvolution method using Wiener filters is utilized in data processing. Using a uniform spatial distribution of laser pulses at the ground's surface, we obtained 3D images of buried objects. The images give us a clear representation of the shapes of the underground objects. The quality of the images depends on the mismatch of acoustic impedance of the buried objects, the bandwidth and center frequency of the acoustic sensors and the selection of filter functions.

  18. New specimen design for studying the growth of small fatigue cracks with surface acoustic waves

    Science.gov (United States)

    London, Blair

    1985-08-01

    The study of small surface fatigue cracks in AISI 4140 quenched and tempered steel by a nondestructive surface acoustic wave technique is summarized. A novel cantilevered bending, plate-type fatigue specimen is described that is compatible with the acoustic method. Small cracks are initiated from a 25-μm deep surface pit produced by an electrospark machine. The importance of studying these cracks which closely approximate naturally occurring fatigue cracks is briefly discussed.

  19. Detection of bioagents using a shear horizontal surface acoustic wave biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Richard S; Hjelle, Brian; Hall, Pam R; Brown, David C; Bisoffi, Marco; Brozik, Susan M; Branch, Darren W; Edwards, Thayne L; Wheeler, David

    2014-04-29

    A biosensor combining the sensitivity of surface acoustic waves (SAW) generated at a frequency of 325 MHz with the specificity provided by antibodies and other ligands for the detection of viral agents. In a preferred embodiment, a lithium tantalate based SAW transducer with silicon dioxide waveguide sensor platform featuring three test and one reference delay lines was used to adsorb antibodies directed against Coxsackie virus B4 or the negative-stranded category A bioagent Sin Nombre virus (SNV). Rapid detection of increasing concentrations of viral particles was linear over a range of order of magnitude for both viruses, and the sensor's selectivity for its target was not compromised by the presence of confounding Herpes Simplex virus type 1 The biosensor was able to delect SNV at doses lower than the load of virus typically found in a human patient suffering from hantavirus cardiopulmonary syndrome (HCPS).

  20. Detection of bioagents using a shear horizontal surface acoustic wave biosensor

    Science.gov (United States)

    Larson, Richard S; Hjelle, Brian; Hall, Pam R; Brown, David C; Bisoffi, Marco; Brozik, Susan M; Branch, Darren W; Edwards, Thayne L; Wheeler, David

    2014-04-29

    A biosensor combining the sensitivity of surface acoustic waves (SAW) generated at a frequency of 325 MHz with the specificity provided by antibodies and other ligands for the detection of viral agents. In a preferred embodiment, a lithium tantalate based SAW transducer with silicon dioxide waveguide sensor platform featuring three test and one reference delay lines was used to adsorb antibodies directed against Coxsackie virus B4 or the negative-stranded category A bioagent Sin Nombre virus (SNV). Rapid detection of increasing concentrations of viral particles was linear over a range of order of magnitude for both viruses, and the sensor's selectivity for its target was not compromised by the presence of confounding Herpes Simplex virus type 1 The biosensor was able to delect SNV at doses lower than the load of virus typically found in a human patient suffering from hantavirus cardiopulmonary syndrome (HCPS).

  1. Non-Axisymmetric Oscillation of Acoustically Levitated Water Drops at Specific Frequencies

    International Nuclear Information System (INIS)

    Chang-Le, Shen; Wen-Jun, Xie; Bing-Bo, Wei

    2010-01-01

    A category of non-axisymmetric oscillations of acoustically levitated water drops was observed. These oscillations can be qualitatively described by superposing a sectorial oscillating term upon the initial oblate shape resulting from the effect of acoustic radiation pressure. The oscillation frequencies are around 25 Hz for the 2-lobed mode and exactly 50 Hz for the 3- and 4-lobed modes. These oscillations were excited by the disturbance from the power supply. For the same water drop, higher mode oscillations were observed with more oblate initial shape, indicating that the eigenfrequencies of these non-axisymmetric oscillations decrease with increasing initial distortion. The maximum velocity and acceleration within the oscillating drop can attain 0.3m·s −1 and 98.7m·s −2 respectively, resulting in strong fluid convection and enhanced heat and mass transfer. (condensed matter: structure, mechanical and thermal properties)

  2. Acoustic energy harvesting based on a planar acoustic metamaterial

    Science.gov (United States)

    Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine

    2016-06-01

    We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.

  3. Phononic fluidics: acoustically activated droplet manipulations

    Science.gov (United States)

    Reboud, Julien; Wilson, Rab; Bourquin, Yannyk; Zhang, Yi; Neale, Steven L.; Cooper, Jonathan M.

    2011-02-01

    Microfluidic systems have faced challenges in handling real samples and the chip interconnection to other instruments. Here we present a simple interface, where surface acoustic waves (SAWs) from a piezoelectric device are coupled into a disposable acoustically responsive microfluidic chip. By manipulating droplets, SAW technologies have already shown their potential in microfluidics, but it has been limited by the need to rely upon mixed signal generation at multiple interdigitated electrode transducers (IDTs) and the problematic resulting reflections, to allow complex fluid operations. Here, a silicon chip was patterned with phononic structures, engineering the acoustic field by using a full band-gap. It was simply coupled to a piezoelectric LiNbO3 wafer, propagating the SAW, via a thin film of water. Contrary to the use of unstructured superstrates, phononic metamaterials allowed precise spatial control of the acoustic energy and hence its interaction with the liquids placed on the surface of the chip, as demonstrated by simulations. We further show that the acoustic frequency influences the interaction between the SAW and the phononic lattice, providing a route to programme complex fluidic manipulation onto the disposable chip. The centrifugation of cells from a blood sample is presented as a more practical demonstration of the potential of phononic crystals to realize diagnostic systems.

  4. Observation of the low-frequency ion acoustic instability in the turbulently heated TRIAM-1 tokamak plasma

    Energy Technology Data Exchange (ETDEWEB)

    Mitarai, O; Watanabe, T; Nakamura, Y; Nakamura, K; Hiraki, N; Toi, K; Kawai, Y; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1980-12-01

    Density fluctuations in the frequency range of several MHz are observed in the turbulently heated TRIAM-1 tokamak plasma by means of a 4 mm microwave scattering method. It is found from the measurement of the dispersion relation that this instability is considered to be the low-frequency ion acoustic instability propagating nearly perpendicular to the toroidal magnetic field.

  5. A consideration on physical tuning for acoustical coloration in recording studio

    Science.gov (United States)

    Shimizu, Yasushi

    2003-04-01

    Coloration due to particular architectural shapes and dimension or less surface absorption has been mentioned as an acoustical defect in recording studio. Generally interference among early reflected sounds arriving within 10 ms in delay after the direct sound produces coloration by comb filter effect over mid- and high-frequency sounds. In addition, less absorbed room resonance modes also have been well known as a major component for coloration in low-frequency sounds. Small size in dimension with recording studio, however, creates difficulty in characterization associated with wave acoustics behavior, that make acoustical optimization more difficult than that of concert hall acoustics. There still remains difficulty in evaluating amount of coloration as well as predicting its acoustical characteristics in acoustical modeling and in other words acoustical tuning technique during construction is regarded as important to optimize acoustics appropriately to the function of recording studio. This paper presents a example of coloration by comb filtering effect and less damped room modes in typical post-processing recording studio. And acoustical design and measurement technique will be presented for adjusting timbre due to coloration based on psycho-acoustical performance with binaural hearing and room resonance control with line array resonator adjusted to the particular room modes considered.

  6. Directional and dynamic modulation of the optical emission of an individual GaAs nanowire using surface acoustic waves.

    Science.gov (United States)

    Kinzel, Jörg B; Rudolph, Daniel; Bichler, Max; Abstreiter, Gerhard; Finley, Jonathan J; Koblmüller, Gregor; Wixforth, Achim; Krenner, Hubert J

    2011-04-13

    We report on optical experiments performed on individual GaAs nanowires and the manipulation of their temporal emission characteristics using a surface acoustic wave. We find a pronounced, characteristic suppression of the emission intensity for the surface acoustic wave propagation aligned with the axis of the nanowire. Furthermore, we demonstrate that this quenching is dynamical as it shows a pronounced modulation as the local phase of the surface acoustic wave is tuned. These effects are strongly reduced for a surface acoustic wave applied in the direction perpendicular to the axis of the nanowire due to their inherent one-dimensional geometry. We resolve a fully dynamic modulation of the nanowire emission up to 678 MHz not limited by the physical properties of the nanowires.

  7. Coherent acoustic phonon oscillation accompanied with backward acoustic pulse below exciton resonance in a ZnO epifilm on oxide-buffered Si(1 1 1)

    International Nuclear Information System (INIS)

    Lin, Ja-Hon; Shen, Yu-Kai; Lu, Chia-Hui; Chen, Yao-Hui; Chang, Chun-peng; Liu, Wei-Rein; Hsu, Chia-Hung; Lee, Wei-Chin; Hong, Minghwei; Kwo, Jueinai-Raynien; Hsieh, Wen-Feng

    2016-01-01

    Unlike coherent acoustic phonons (CAPs) generated from heat induced thermal stress by the coated Au film, we demonstrated the oscillation from c-ZnO epitaxial film on oxide buffered Si through a degenerate pump–probe technique. As the excited photon energy was set below the exciton resonance, the electronic stress that resulted from defect resonance was used to induce acoustic wave. The damped oscillation revealed a superposition of a high frequency and long decay CAP signal with a backward propagating acoustic pulse which was generated by the absorption of the penetrated pump beam at the Si surface and selected by the ZnO layer as the acoustic resonator. (paper)

  8. Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

    International Nuclear Information System (INIS)

    Kryshtal, R.G.; Medved, A.V.

    2015-01-01

    Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW – magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW – magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW – magnonic crystals are promising for signal processing in the GHz range. - Highlights: • Spin waves nonreciprocity in YIG magnonic crystals with SAW was studied. • SAW was shown to create nonreciprocity for spin waves in YIG–GGG even without metal. • Frequency and width of magnonic band gaps were measured versus metal conductivity. • Conductivity for practical use of spin waves in the structure YIG–metal was defined

  9. Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

    Energy Technology Data Exchange (ETDEWEB)

    Kryshtal, R.G.; Medved, A.V., E-mail: avm@ms.ire.rssi.ru

    2015-12-01

    Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW – magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW – magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW – magnonic crystals are promising for signal processing in the GHz range. - Highlights: • Spin waves nonreciprocity in YIG magnonic crystals with SAW was studied. • SAW was shown to create nonreciprocity for spin waves in YIG–GGG even without metal. • Frequency and width of magnonic band gaps were measured versus metal conductivity. • Conductivity for practical use of spin waves in the structure YIG–metal was defined.

  10. Acoustical contribution calculation and analysis of compressor shell based on acoustic transfer vector method

    Science.gov (United States)

    Chen, Xiaol; Guo, Bei; Tuo, Jinliang; Zhou, Ruixin; Lu, Yang

    2017-08-01

    Nowadays, people are paying more and more attention to the noise reduction of household refrigerator compressor. This paper established a sound field bounded by compressor shell and ISO3744 standard field points. The Acoustic Transfer Vector (ATV) in the sound field radiated by a refrigerator compressor shell were calculated which fits the test result preferably. Then the compressor shell surface is divided into several parts. Based on Acoustic Transfer Vector approach, the sound pressure contribution to the field points and the sound power contribution to the sound field of each part were calculated. To obtain the noise radiation in the sound field, the sound pressure cloud charts were analyzed, and the contribution curves in different frequency of each part were acquired. Meanwhile, the sound power contribution of each part in different frequency was analyzed, to ensure those parts where contributes larger sound power. Through the analysis of acoustic contribution, those parts where radiate larger noise on the compressor shell were determined. This paper provides a credible and effective approach on the structure optimal design of refrigerator compressor shell, which is meaningful in the noise and vibration reduction.

  11. A role for acoustic distortion in novel rapid frequency modulation behaviour in free-flying male mosquitoes.

    Science.gov (United States)

    Simões, Patrício M V; Ingham, Robert A; Gibson, Gabriella; Russell, Ian J

    2016-07-01

    We describe a new stereotypical acoustic behaviour by male mosquitoes in response to the fundamental frequency of female flight tones during mating sequences. This male-specific free-flight behaviour consists of phonotactic flight beginning with a steep increase in wing-beat frequency (WBF) followed by rapid frequency modulation (RFM) of WBF in the lead up to copula formation. Male RFM behaviour involves remarkably fast changes in WBF and can be elicited without acoustic feedback or physical presence of the female. RFM features are highly consistent, even in response to artificial tones that do not carry the multi-harmonic components of natural female flight tones. Comparison between audiograms of the robust RFM behaviour and the electrical responses of the auditory Johnston's organ (JO) reveals that the male JO is tuned not to the female WBF per se but, remarkably, to the difference between the male and female WBFs. This difference is generated in the JO responses as a result of intermodulation distortion products (DPs) caused by non-linear interaction between male-female flight tones in the vibrations of the antenna. We propose that male mosquitoes rely on their own flight tones in making use of DPs to acoustically detect, locate and orientate towards flying females. We argue that the previously documented flight-tone harmonic convergence of flying male and female mosquitoes could be a consequence of WBF adjustments so that DPs generated through flight-tone interaction fall within the optimal frequency ranges for JO detection. © 2016. Published by The Company of Biologists Ltd.

  12. A frequency domain linearized Navier-Stokes equations approach to acoustic propagation in flow ducts with sharp edges.

    Science.gov (United States)

    Kierkegaard, Axel; Boij, Susann; Efraimsson, Gunilla

    2010-02-01

    Acoustic wave propagation in flow ducts is commonly modeled with time-domain non-linear Navier-Stokes equation methodologies. To reduce computational effort, investigations of a linearized approach in frequency domain are carried out. Calculations of sound wave propagation in a straight duct are presented with an orifice plate and a mean flow present. Results of transmission and reflections at the orifice are presented on a two-port scattering matrix form and are compared to measurements with good agreement. The wave propagation is modeled with a frequency domain linearized Navier-Stokes equation methodology. This methodology is found to be efficient for cases where the acoustic field does not alter the mean flow field, i.e., when whistling does not occur.

  13. High-resolution acoustic imaging at low frequencies using 3D-printed metamaterials

    Directory of Open Access Journals (Sweden)

    S. Laureti

    2016-12-01

    Full Text Available An acoustic metamaterial has been constructed using 3D printing. It contained an array of air-filled channels, whose size and shape could be varied within the design and manufacture process. In this paper we analyze both numerically and experimentally the properties of this polymer metamaterial structure, and demonstrate its use for the imaging of a sample with sub-wavelength dimensions in the audible frequency range.

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

    Science.gov (United States)

    Hines, Jacqueline H. (Inventor)

    2015-01-01

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

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

    DEFF Research Database (Denmark)

    Gulyaev, Yuri V.

    1974-01-01

    acoustoelectric effect but also lead to amplification of surface acoustic waves by electron drift perpendicular to the surface. For Love waves in a piezoelectric semiconductor film on a highly conducting substrate, the amplification coefficient is found and the conditions necessary for amplification...

  16. Acoustic waveform of continuous bubbling in a non-Newtonian fluid.

    Science.gov (United States)

    Vidal, Valérie; Ichihara, Mie; Ripepe, Maurizio; Kurita, Kei

    2009-12-01

    We study experimentally the acoustic signal associated with a continuous bubble bursting at the free surface of a non-Newtonian fluid. Due to the fluid rheological properties, the bubble shape is elongated, and, when bursting at the free surface, acts as a resonator. For a given fluid concentration, at constant flow rate, repetitive bubble bursting occurs at the surface. We report a modulation pattern of the acoustic waveform through time. Moreover, we point out the existence of a precursor acoustic signal, recorded on the microphone array, previous to each bursting. The time delay between this precursor and the bursting signal is well correlated with the bursting signal frequency content. Their joint modulation through time is driven by the fluid rheology, which strongly depends on the presence of small satellite bubbles trapped in the fluid due to the yield stress.

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

    Science.gov (United States)

    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

  18. Development of Energy Efficiency Design Map based on acoustic resonance frequency of suction muffler in compressor

    International Nuclear Information System (INIS)

    Oh, Seungjae; Wang, Semyung; Cho, Sungman

    2015-01-01

    Highlights: • Development of Energy Efficiency Design Map. • Experimental validation of Energy Efficiency Design Map. • Suggestion regarding the Acoustically Supercharged Energy Efficiency. • Sensitivity analysis of the Energy Efficiency Ratio with respect to acoustic pressure. • Suggestion regarding the hybrid coupling method for acoustic analysis in compressor. - Abstract: The volumetric efficiency of the Internal Combustion (IC) engine and compressor can be increased by properly adjusting the acoustic resonance frequency of the suction muffler or the suction valve timing without any additional equipment or power source. This effect is known as acoustic supercharging. However, the energy efficiency has become more important than the volumetric efficiency because of the energy shortage issue and factors influencing consumers’ purchasing decisions. Therefore, methods for increasing the energy efficiency using the acoustic effect in the suction part of IC engine and compressor should be considered. In this study, a systematic method for improving the energy efficiency using the acoustic effect in the suction part of the compressor used in refrigerators and air conditioners was developed for the first time. This effect is named as the Acoustically Supercharged Energy Efficiency (ASEE). For the ASEE, first, a hybrid coupling method was suggested for the acoustical analysis in the suction part of the compressor. Next, an Energy Efficiency Design Map (EEDM) was proposed. This can serve as a design guide for suction mufflers in terms of the energy efficiency. Finally, sensitivity analyses of the Energy Efficiency Ratio (EER) and total massflow rate with respect to the acoustic pressure were conducted to identify the relationship between the acoustic pressure and the suction valve motion. This provides the physical background for the EEDM

  19. The Influence of Sensor Size on Acoustic Emission Waveforms—A Numerical Study

    Directory of Open Access Journals (Sweden)

    Eleni Tsangouri

    2018-01-01

    Full Text Available The performance of Acoustic Emission technique is governed by the measuring efficiency of the piezoelectric sensors usually mounted on the structure surface. In the case of damage of bulk materials or plates, the sensors receive the acoustic waveforms of which the frequency and shape are correlated to the damage mode. This numerical study measures the waveforms received by point, medium and large size sensors and evaluates the effect of sensor size on the acoustic emission signals. Simulations are the only way to quantify the effect of sensor size ensuring that the frequency response of the different sensors is uniform. The cases of horizontal (on the same surface, vertical and diagonal excitation are numerically simulated, and the corresponding elastic wave displacement is measured for different sizes of sensors. It is shown that large size sensors significantly affect the wave magnitude and content in both time and frequency domains and especially in the case of surface wave excitation. The coherence between the original and received waveform is quantified and the numerical findings are experimentally supported. It is concluded that sensors with a size larger than half the size of the excitation wavelength start to seriously influence the accuracy of the AE waveform.

  20. Fatigue crack propagation of super duplex stainless steel with dispersed structure and time-frequency analysis of acoustic emission

    Science.gov (United States)

    Nam, Ki-Woo; Kang, Chang-Yong; Do, Jae-Yoon; Ahn, Seok-Hwan; Lee, Sang-Kee

    2001-06-01

    The fatigue crack propagation of super duplex stainless steel was investigated for the effect of various volume fractions of the austenite phase by changing the heat treatment temperature. We also analyzed acoustic emission signals obtained during the fatigue crack propagation by the time-frequency analysis method. As the temperature of the heat treatment increased, the volume fraction of austenite decreased and coarse grain was obtained. The specimen treated at 1200 had a longer fatigue life and slower rate of crack growth. Results of time-frequency analysis of acoustic emission signals during the fatigue test showed the main frequency of 200-300 kHz to have no correlation with heat treatment and crack length, and the 500 kHz signal to be due to dimples and separation of inclusion.

  1. Nonadiabaticity and single-electron transport driven by surface acoustic waves

    DEFF Research Database (Denmark)

    Flensberg, Karsten; Niu, Q.; Pustilnik, M.

    1999-01-01

    Single-electron transport driven by surface acoustic waves (SAW) through a narrow constriction, formed in a two-dimensional electron gas, is studied theoretically. Due to long-range Coulomb interaction, the tunneling coupling between the electron gas and the moving minimum of the SAW...

  2. Detection of Volatile Organics Using a Surface Acoustic Wave Array System

    International Nuclear Information System (INIS)

    ANDERSON, LAWRENCE F.; BARTHOLOMEW, JOHN W.; CERNOSEK, RICHARD W.; COLBURN, CHRISTOPHER W.; CROOKS, R.M.; MARTINEZ, R.F.; OSBOURN, GORDON C.; RICCO, A.J.; STATON, ALAN W.; YELTON, WILLIAM G.

    1999-01-01

    A chemical sensing system based on arrays of surface acoustic wave (SAW) delay lines has been developed for identification and quantification of volatile organic compounds (VOCs). The individual SAW chemical sensors consist of interdigital transducers patterned on the surface of an ST-cut quartz substrate to launch and detect the acoustic waves and a thin film coating in the SAW propagation path to perturb the acoustic wave velocity and attenuation during analyte sorption. A diverse set of material coatings gives the sensor arrays a degree of chemical sensitivity and selectivity. Materials examined for sensor application include the alkanethiol-based self-assembled monolayer, plasma-processed films, custom-synthesized conventional polymers, dendrimeric polymers, molecular recognition materials, electroplated metal thin films, and porous metal oxides. All of these materials target a specific chemical fi.mctionality and the enhancement of accessible film surface area. Since no one coating provides absolute analyte specificity, the array responses are further analyzed using a visual-empirical region-of-influence (VERI) pattern recognition algorithm. The chemical sensing system consists of a seven-element SAW array with accompanying drive and control electronics, sensor signal acquisition electronics, environmental vapor sampling hardware, and a notebook computer. Based on data gathered for individual sensor responses, greater than 93%-accurate identification can be achieved for any single analyte from a group of 17 VOCs and water

  3. Detection of Volatile Organics Using a Surface Acoustic Wave Array System

    Energy Technology Data Exchange (ETDEWEB)

    ANDERSON, LAWRENCE F.; BARTHOLOMEW, JOHN W.; CERNOSEK, RICHARD W.; COLBURN, CHRISTOPHER W.; CROOKS, R.M.; MARTINEZ, R.F.; OSBOURN, GORDON C.; RICCO, A.J.; STATON, ALAN W.; YELTON, WILLIAM G.

    1999-10-14

    A chemical sensing system based on arrays of surface acoustic wave (SAW) delay lines has been developed for identification and quantification of volatile organic compounds (VOCs). The individual SAW chemical sensors consist of interdigital transducers patterned on the surface of an ST-cut quartz substrate to launch and detect the acoustic waves and a thin film coating in the SAW propagation path to perturb the acoustic wave velocity and attenuation during analyte sorption. A diverse set of material coatings gives the sensor arrays a degree of chemical sensitivity and selectivity. Materials examined for sensor application include the alkanethiol-based self-assembled monolayer, plasma-processed films, custom-synthesized conventional polymers, dendrimeric polymers, molecular recognition materials, electroplated metal thin films, and porous metal oxides. All of these materials target a specific chemical fi.mctionality and the enhancement of accessible film surface area. Since no one coating provides absolute analyte specificity, the array responses are further analyzed using a visual-empirical region-of-influence (VERI) pattern recognition algorithm. The chemical sensing system consists of a seven-element SAW array with accompanying drive and control electronics, sensor signal acquisition electronics, environmental vapor sampling hardware, and a notebook computer. Based on data gathered for individual sensor responses, greater than 93%-accurate identification can be achieved for any single analyte from a group of 17 VOCs and water.

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

    Science.gov (United States)

    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.

  5. Direct and sustained intracellular delivery of exogenous molecules using acoustic-transfection with high frequency ultrasound

    Science.gov (United States)

    Yoon, Sangpil; Kim, Min Gon; Chiu, Chi Tat; Hwang, Jae Youn; Kim, Hyung Ham; Wang, Yingxiao; Shung, K. Kirk

    2016-02-01

    Controlling cell functions for research and therapeutic purposes may open new strategies for the treatment of many diseases. An efficient and safe introduction of membrane impermeable molecules into target cells will provide versatile means to modulate cell fate. We introduce a new transfection technique that utilizes high frequency ultrasound without any contrast agents such as microbubbles, bringing a single-cell level targeting and size-dependent intracellular delivery of macromolecules. The transfection apparatus consists of an ultrasonic transducer with the center frequency of over 150 MHz and an epi-fluorescence microscope, entitled acoustic-transfection system. Acoustic pulses, emitted from an ultrasonic transducer, perturb the lipid bilayer of the cell membrane of a targeted single-cell to induce intracellular delivery of exogenous molecules. Simultaneous live cell imaging using HeLa cells to investigate the intracellular concentration of Ca2+ and propidium iodide (PI) and the delivery of 3 kDa dextran labeled with Alexa 488 were demonstrated. Cytosolic delivery of 3 kDa dextran induced via acoustic-transfection was manifested by diffused fluorescence throughout whole cells. Short-term (6 hr) cell viability test and long-term (40 hr) cell tracking confirmed that the proposed approach has low cell cytotoxicity.

  6. Numerical calculation of acoustic radiation from band-vibrating structures via FEM/FAQP method

    Directory of Open Access Journals (Sweden)

    GAO Honglin

    2017-08-01

    Full Text Available The Finite Element Method (FEM combined with the Frequency Averaged Quadratic Pressure method (FAQP are used to calculate the acoustic radiation of structures excited in the frequency band. The surface particle velocity of stiffened cylindrical shells under frequency band excitation is calculated using finite element software, the normal vibration velocity is converted from the surface particle velocity to calculate the average energy source (frequency averaged across intensity, frequency averaged across pressure and frequency averaged across velocity, and the FAQP method is used to calculate the average sound pressure level within the bandwidth. The average sound pressure levels are then compared with the bandwidth using finite element and boundary element software, and the results show that FEM combined with FAQP is more suitable for high frequencies and can be used to calculate the average sound pressure level in the 1/3 octave band with good stability, presenting an alternative to applying frequency-by-frequency calculation and the average frequency process. The FEM/FAQP method can be used as a prediction method for calculating acoustic radiation while taking the randomness of vibration at medium and high frequencies into consideration.

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

    International Nuclear Information System (INIS)

    Zhang Zuwei; Wen Zhiyu; Hu Jing

    2013-01-01

    The propagation properties of the surface acoustic waves (SAWs) in a ZnO—SiO 2 —Si multilayered piezoelectric structure are calculated by using the recursive asymptotic method. The phase velocities and the electromechanical coupling coefficients for the Rayleigh wave and the Love wave in the different ZnO—SiO 2 —Si structures are calculated and analyzed. The Love mode wave is found to be predominantly generated since the c-axis of the ZnO film is generally perpendicular to the substrate. In order to prove the calculated results, a Love mode SAW device based on the ZnO—SiO 2 —Si multilayered structure is fabricated by micromachining, and its frequency responses are detected. The experimental results are found to be mainly consistent with the calculated ones, except for the slightly larger velocities induced by the residual stresses produced in the fabrication process of the films. The deviation of the experimental results from the calculated ones is reduced by thermal annealing. (semiconductor physics)

  8. Surface gravity waves and their acoustic signatures, 1-30 Hz, on the mid-Pacific sea floor.

    Science.gov (United States)

    Farrell, W E; Munk, Walter

    2013-10-01

    In 1999, Duennebier et al. deployed a hydrophone and geophone below the conjugate depth in the abyssal Pacific, midway between Hawaii and California. Real time data were transmitted for 3 yr over an abandoned ATT cable. These data have been analyzed in the frequency band 1 to 30 Hz. Between 1 and 6 Hz, the bottom data are interpreted as acoustic radiation from surface gravity waves, an extension to higher frequencies of a non-linear mechanism proposed by Longuet-Higgins in 1950 to explain microseisms. The inferred surface wave spectrum for wave lengths between 6 m and 17 cm is saturated (wind-independent) and roughly consistent with the traditional Phillips κ(-4) wave number spectrum. Shorter ocean waves have a strong wind dependence and a less steep wave number dependence. Similar features are found in the bottom record between 6 and 30 Hz. But this leads to an enigma: The derived surface spectrum inferred from the Longuet-Higgins mechanism with conventional assumptions for the dispersion relation is associated with mean square slopes that greatly exceed those derived from glitter. Regardless of the generation mechanism, the measured bottom intensities between 10 and 30 Hz are well below minimum noise standards reported in the literature.

  9. Control of low-frequency noise for piping systems via the design of coupled band gap of acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yanfei [College of Power Engineering, Naval University of Engineering, Wuhan, 430033 (China); Shen, Huijie, E-mail: shj588@163.com [College of Power Engineering, Naval University of Engineering, Wuhan, 430033 (China); Zhang, Linke [School of Energy and Power Engineering, Wuhan University of Technology, Wuhan, 430063 (China); Su, Yongsheng, E-mail: suyongsheng1981@163.com [College of Power Engineering, Naval University of Engineering, Wuhan, 430033 (China); Yu, Dianlong [Key Laboratory of Science and Technology on Integrated Logistics Support, National University of Defense Technology, Changsha 410073 (China)

    2016-07-01

    Acoustic wave propagation and sound transmission in a metamaterial-based piping system with Helmholtz resonator (HR) attached periodically are studied. A transfer matrix method is developed to conduct the investigation. Calculational results show that the introduction of periodic HRs in the piping system could generate a band gap (BG) near the resonant frequency of the HR, such that the bandwidth and the attenuation effect of HR improved notably. Bragg type gaps are also exist in the system due to the systematic periodicity. By plotting the BG as functions of HR parameters, the effect of resonator parameters on the BG behavior, including bandwidth, location and attenuation performance, etc., is examined. It is found that Bragg-type gap would interplay with the resonant-type gap under some special situations, thereby giving rise to a super-wide coupled gap. Further, explicit formulation for BG exact coupling is extracted and some key parameters on modulating the width and the attenuation coefficient of coupled gaps are investigated. The coupled gap can be located to any frequency range as one concerned, thus rendering the low-frequency noise control feasible in a broad band range. - Highlights: • A metamaterial-type pipe system with Bragg and resonant acoustic gaps. • A low-frequency acoustic coupled gap. • Exact coupling condition for Bragg and resonant gaps. • Effects of resonant parameters on coupled gaps.

  10. Numerical study of acoustophoretic motion of particles in a PDMS microchannel driven by surface acoustic waves.

    Science.gov (United States)

    Nama, Nitesh; Barnkob, Rune; Mao, Zhangming; Kähler, Christian J; Costanzo, Francesco; Huang, Tony Jun

    2015-06-21

    We present a numerical study of the acoustophoretic motion of particles suspended in a liquid-filled PDMS microchannel on a lithium niobate substrate acoustically driven by surface acoustic waves. We employ a perturbation approach where the flow variables are divided into first- and second-order fields. We use impedance boundary conditions to model the PDMS microchannel walls and we model the acoustic actuation by a displacement function from the literature based on a numerical study of piezoelectric actuation. Consistent with the type of actuation, the obtained first-order field is a horizontal standing wave that travels vertically from the actuated wall towards the upper PDMS wall. This is in contrast to what is observed in bulk acoustic wave devices. The first-order fields drive the acoustic streaming, as well as the time-averaged acoustic radiation force acting on suspended particles. We analyze the motion of suspended particles driven by the acoustic streaming drag and the radiation force. We examine a range of particle diameters to demonstrate the transition from streaming-drag-dominated acoustophoresis to radiation-force-dominated acoustophoresis. Finally, as an application of our numerical model, we demonstrate the capability to tune the position of the vertical pressure node along the channel width by tuning the phase difference between two incoming surface acoustic waves.

  11. Panel acoustic contribution analysis.

    Science.gov (United States)

    Wu, Sean F; Natarajan, Logesh Kumar

    2013-02-01

    Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated.

  12. Opto-Acoustic Method for the Characterization of Thin-Film Adhesion

    Directory of Open Access Journals (Sweden)

    Sanichiro Yoshida

    2016-05-01

    Full Text Available The elastic property of the film-substrate interface of thin-film systems is characterized with an opto-acoustic method. The thin-film specimens are oscillated with an acoustic transducer at audible frequencies, and the resultant harmonic response of the film surface is analyzed with optical interferometry. Polystyrene, Ti, Ti-Au and Ti-Pt films coated on the same silicon substrate are tested. For each film material, a pair of specimens is prepared; one is coated on a silicon substrate after the surface is treated with plasma bombardment, and the other is coated on an identical silicon substrate without a treatment. Experiments indicate that both the surface-treated and untreated specimens of all film materials have resonance in the audible frequency range tested. The elastic constant of the interface corresponding to the observed resonance is found to be orders of magnitude lower than that of the film or substrate material. Observations of these resonance-like behaviors and the associated stiffness of the interface are discussed.

  13. Surface Acoustic Bloch Oscillations, the Wannier-Stark Ladder, and Landau-Zener Tunneling in a Solid

    Science.gov (United States)

    de Lima, M. M., Jr.; Kosevich, Yu. A.; Santos, P. V.; Cantarero, A.

    2010-04-01

    We present the experimental observation of Bloch oscillations, the Wannier-Stark ladder, and Landau-Zener tunneling of surface acoustic waves in perturbed grating structures on a solid substrate. A model providing a quantitative description of our experimental observations, including multiple Landau-Zener transitions of the anticrossed surface acoustic Wannier-Stark states, is developed. The use of a planar geometry for the realization of the Bloch oscillations and Landau-Zener tunneling allows a direct access to the elastic field distribution. The vertical surface displacement has been measured by interferometry.

  14. Panama City 2003 Acoustic Coherence Experiments: Low Frequency Bottom Penetration Fluctuation Measurements in a Multipath Environment

    Science.gov (United States)

    Meredith, Roger W.; Kennedy, E. Ted; Malley, Dexter; Fisher, Robert A.; Brown, Robert; Stanic, Steve

    2004-11-01

    This paper is part of a series of papers describing acoustic coherence and fluctuations measurements made by the Naval Research Laboratory in the Gulf of Mexico near Panama City Beach, FL during June 2003. This paper presents low frequency (1-10 kHz) buried hydrophone measurements and preliminary results for two source-receiver ranges with grazing angles less than two degrees (realtive to the direct-path to the seafloor at the receiver location). Results focus on fluctuations after acoustic penetration into the sediment. These fluctuations are correlated with environmental influences.

  15. High frequency source localization in a shallow ocean sound channel using frequency difference matched field processing.

    Science.gov (United States)

    Worthmann, Brian M; Song, H C; Dowling, David R

    2015-12-01

    Matched field processing (MFP) is an established technique for source localization in known multipath acoustic environments. Unfortunately, in many situations, particularly those involving high frequency signals, imperfect knowledge of the actual propagation environment prevents accurate propagation modeling and source localization via MFP fails. For beamforming applications, this actual-to-model mismatch problem was mitigated through a frequency downshift, made possible by a nonlinear array-signal-processing technique called frequency difference beamforming [Abadi, Song, and Dowling (2012). J. Acoust. Soc. Am. 132, 3018-3029]. Here, this technique is extended to conventional (Bartlett) MFP using simulations and measurements from the 2011 Kauai Acoustic Communications MURI experiment (KAM11) to produce ambiguity surfaces at frequencies well below the signal bandwidth where the detrimental effects of mismatch are reduced. Both the simulation and experimental results suggest that frequency difference MFP can be more robust against environmental mismatch than conventional MFP. In particular, signals of frequency 11.2 kHz-32.8 kHz were broadcast 3 km through a 106-m-deep shallow ocean sound channel to a sparse 16-element vertical receiving array. Frequency difference MFP unambiguously localized the source in several experimental data sets with average peak-to-side-lobe ratio of 0.9 dB, average absolute-value range error of 170 m, and average absolute-value depth error of 10 m.

  16. A Comparative Study of the Monitoring of a Self Aligning Spherical Journal using Surface Vibration, Airborne Sound and Acoustic Emission

    International Nuclear Information System (INIS)

    Raharjo, P; Tesfa, B; Gu, F; Ball, A D

    2012-01-01

    A Self aligning spherical journal bearing is a plain bearing which has spherical surface contact that can be applied in high power industrial machinery. This type of bearing can accommodate a misalignment problem. The journal bearing faults degrade machine performance, decrease life time service and cause unexpected failure which are dangerous for safety issues. Non-intrusive measurements such as surface vibration (SV), airborne sound (AS) and acoustic emission (AE) measurement are appropriate monitoring methods for early stage journal bearing fault in low, medium and high frequency. This paper focuses on the performance comparison using SV, AS and AE measurements in monitoring a self aligning spherical journal bearing for normal and faulty (scratch) conditions. It examines the signals in the time domain and frequency domain and identifies the frequency ranges for each measurement in which significant changes are observed. The results of SV, AS and AE experiments indicate that the spectrum can be used to detect the differences between normal and faulty bearing. The statistic parameter shows that RMS value and peak value for faulty bearing is higher than normal bearing.

  17. Flame-vortex interaction and mixing behaviors of turbulent non-premixed jet flames under acoustic forcing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Munki; Choi, Youngil; Oh, Jeongseog; Yoon, Youngbin [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea)

    2009-12-15

    This study examines the effect of acoustic excitation using forced coaxial air on the flame characteristics of turbulent hydrogen non-premixed flames. A resonance frequency was selected to acoustically excite the coaxial air jet due to its ability to effectively amplify the acoustic amplitude and reduce flame length and NO{sub x} emissions. Acoustic excitation causes the flame length to decrease by 15% and consequently, a 25% reduction in EINO{sub x} is achieved, compared to coaxial air flames without acoustic excitation at the same coaxial air to fuel velocity ratio. Moreover, acoustic excitation induces periodical fluctuation of the coaxial air velocity, thus resulting in slight fluctuation of the fuel velocity. From phase-lock PIV and OH PLIF measurement, the local flow properties at the flame surface were investigated under acoustic forcing. During flame-vortex interaction in the near field region, the entrainment velocity and the flame surface area increased locally near the vortex. This increase in flame surface area and entrainment velocity is believed to be a crucial factor in reducing flame length and NO{sub x} emission in coaxial jet flames with acoustic excitation. Local flame extinction occurred frequently when subjected to an excessive strain rate, indicating that intense mass transfer of fuel and air occurs radially inward at the flame surface. (author)

  18. Helium gas purity monitor based on low frequency acoustic resonance

    Science.gov (United States)

    Kasthurirengan, S.; Jacob, S.; Karunanithi, R.; Karthikeyan, A.

    1996-05-01

    Monitoring gas purity is an important aspect of gas recovery stations where air is usually one of the major impurities. Purity monitors of Katherometric type are commercially available for this purpose. Alternatively, we discuss here a helium gas purity monitor based on acoustic resonance of a cavity at audio frequencies. It measures the purity by monitoring the resonant frequency of a cylindrical cavity filled with the gas under test and excited by conventional telephone transducers fixed at the ends. The use of the latter simplifies the design considerably. The paper discusses the details of the resonant cavity and the electronic circuit along with temperature compensation. The unit has been calibrated with helium gas of known purities. The unit has a response time of the order of 10 minutes and measures the gas purity to an accuracy of 0.02%. The unit has been installed in our helium recovery system and is found to perform satisfactorily.

  19. High frequency and pulse scattering physical acoustics

    CERN Document Server

    Pierce, Allan D

    1992-01-01

    High Frequency and Pulse Scattering investigates high frequency and pulse scattering, with emphasis on the phenomenon of echoes from objects. Geometrical and catastrophe optics methods in scattering are discussed, along with the scattering of sound pulses and the ringing of target resonances. Caustics and associated diffraction catastrophes are also examined.Comprised of two chapters, this volume begins with a detailed account of geometrically based approximation methods in scattering theory, focusing on waves transmitted through fluid and elastic scatterers and glory scattering; surface ray r

  20. Simulation of an Underwater Acoustic Communication Channel Characterized by Wind-Generated Surface Waves and Bubbles

    NARCIS (Netherlands)

    Dol, H.S.; Colin, M.E.G.D.; Ainslie, M.A.; Walree, P.A. van; Janmaat, J.

    2012-01-01

    Sea surface scattering by wind-generated waves and bubbles is regarded to be the main non-platform related cause of the time variability of shallow acoustic communication channels. Simulations for predicting the quality of acoustic communication links in such channels thus require adequate modeling

  1. Acoustic streaming enhanced electrodeposition of nickel

    DEFF Research Database (Denmark)

    Jensen, Jens Dahl; Møller, Per

    2003-01-01

    Electrochemical deposition of Ni from a Watts-type electrolyte under the influence of high frequency ultrasound at both high (250 W) and low (5–10 W) power sonication was investigated. An improvement in the material distribution of the deposited Ni in millimeter-sized groove-features on the catho......-patterns on the surface of the deposit and near-boundary acoustic streaming....

  2. Microscopic Behavior Of Colloidal Particles Under The Effect Of Acoustic Stimulations In The Ultrasonic To Megasonic Range

    Science.gov (United States)

    Abdel-Fattah, Amr I.; Roberts, Peter M.

    2006-05-01

    It is well known that colloid attachment and detachment at solid surfaces are influenced strongly by physico-chemical conditions controlling electric double layer (EDL) and solvation-layer effects. We present experimental observations demonstrating that, in addition, acoustic waves can produce strong effects on colloid/surface interactions that can alter the behavior of colloid and fluid transport in porous media. Microscopic colloid visualization experiments were performed with polystyrene micro-spheres suspended in water in a parallel-plate glass flow cell. When acoustic energy was applied to the cell at frequencies from 500 kHz to 5 MHz, changes in colloid attachment to and detachment from the glass cell surfaces were observed. Quantitative measurements of acoustically-induced detachment of 300-nm microspheres in 0.1M NaCl solution demonstrated that roughly 30% of the colloids that were attached to the glass cell wall during flow alone could be detached rapidly by applying acoustics at frequencies in the range of 0.7 to 1.2 MHz. The remaining attached colloids could not be detached by acoustics. This implies the existence of both "strong" and "weak" attachment sites at the cell surface. Subsequent re-attachment of colloids with acoustics turned off occurred only at new, previously unoccupied sites. Thus, acoustics appears to accelerate simultaneously both the deactivation of existing weak sites where colloids are already attached, and the activation of new weak sites where future attachments can occur. Our observations indicate that acoustics (and, in general, dynamic stress) can influence colloid-colloid and colloid-surface interactions in ways that could cause significant changes in porous-media permeability and mass transport. This would occur due to either buildup or release of colloids present in the porous matrix.

  3. Coupled Acoustic-Mechanical Bandgaps

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Kook, Junghwan

    2016-01-01

    medium and the presence of acoustic resonances. It is demonstrated that corrugation of the plate structure can introduce bending wave bandgaps and bandgaps in the acoustic domain in overlapping and audible frequency ranges. This effect is preserved also when taking the physical coupling between the two...... domains into account. Additionally, the coupling is shown to introduce extra gaps in the band structure due to modal interaction and the appearance of a cut-on frequency for the fundamental acoustic mode....

  4. Receptivity to free stream acoustic disturbances due to a roughness element on a flat plate

    OpenAIRE

    Ashour, Osama Naim

    1993-01-01

    The boundary-layer receptivity resulting from acoustic forcing over a flat plate with a surface irregularity is investigated. The unsteady free-stream disturbances couple with the steady perturbations resulting from the surface irregularity to form a traveling-wave mode. The resonance condition necessary for receptivity requires a forcing at a wave number equal to that of the Tollmien-Schlichting (TS) eigenmode and a frequency equal to that of the free-stream acoustic disturban...

  5. Toward wideband steerable acoustic metasurfaces with arrays of active electroacoustic resonators

    Science.gov (United States)

    Lissek, Hervé; Rivet, Etienne; Laurence, Thomas; Fleury, Romain

    2018-03-01

    We introduce an active concept for achieving acoustic metasurfaces with steerable reflection properties, effective over a wide frequency band. The proposed active acoustic metasurface consists of a surface array of subwavelength loudspeaker diaphragms, each with programmable individual active acoustic impedances allowing for local control over the different reflection phases over the metasurface. The active control framework used for controlling the reflection phase over the metasurface is derived from the Active Electroacoustic Resonator concept. Each unit-cell simply consists of a current-driven electrodynamic loudspeaker in a closed box, whose acoustic impedance at the diaphragm is judiciously adjusted by connecting an active electrical control circuit. The control is known to achieve a wide variety of acoustic impedances on a single loudspeaker diaphragm used as an acoustic resonator, with the possibility to shift its resonance frequency by more than one octave. This paper presents a methodology for designing such active metasurface elements. An experimental validation of the achieved individual reflection coefficients is presented, and full wave simulations present a few examples of achievable reflection properties, with a focus on the bandwidth of operation of the proposed control concept.

  6. Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

    Science.gov (United States)

    Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

    2018-01-01

    Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

  7. Acoustic Surface Cavitation

    NARCIS (Netherlands)

    Zijlstra, A.G.

    2011-01-01

    Merely the presence of compressible entities, known as bubbles, greatly enriches the physical phenomena encountered when introducing ultrasound in a liquid. Mediated by the response of these bubbles, the otherwise diffuse and relatively low energy density of the acoustic field can induce strong,

  8. Influence of a single lightning discharge on the intensity of an air electric field and acoustic emission of near-surface rocks

    Directory of Open Access Journals (Sweden)

    S. E. Smirnov

    2012-10-01

    Full Text Available The effect was observed as a sharp fall of the electric potential gradient from +80 V m−1 down to –21 V m−1. After that the field returned to its normal level according to the formula of the capacitor discharge with 17 s characteristic time. Simultaneously, the response of the acoustic emission of surface rocks in the range of frequencies between 6.5 kHz and 11 kHz was evaluated.

  9. Leaky surface acoustic waves in Z-LiNbO3 substrates with epitaxial AIN overlays

    International Nuclear Information System (INIS)

    Bu, G.; Ciplys, D.; Shur, M.S.; Namkoong, G.; Doolittle, W.A.; Hunt, W.D.

    2004-01-01

    The properties of leaky surface acoustic waves (LSAW) in MBE grown AIN layer on Z-cut LiNbO 3 structures have been studied by numerical simulation and experimental measurements and compared with those of Rayleigh waves in the same structure. In the range of AIN layer thicknesses studied (0 3 substrate was essentially constant at around 4400 m/s. The measured electromechanical coupling coefficients (K 2 ) for the LSAW are roughly 1/4 of the predicted values, which might be due to the strong attenuation of the leaky wave unaccounted for during the parameter extraction. The thin AIN film slightly improved the measured temperature coefficient of frequency for the LSAW over that attained for the Z-cut, X-propagating LiNbO 3 substrate alone

  10. Influence of statistical surface models on dynamic scattering of high-frequency signals from the ocean surface (A)

    DEFF Research Database (Denmark)

    Bjerrum-Niese, Christian; Jensen, Leif Bjørnø

    1994-01-01

    ; the surface roughness is described by a spatial surface spectrum and the surface motion is described by the gravity-wave dispersion relation [D. Dowling and D. Jackson, J. Acoust. Soc. Am. 93, 3149–3157 (1993)]. Applying some modifications to this approach, the temporal coherence function is found...

  11. Applying of the array transducers' technology for surface acoustic waves materials characterization in the transient regime

    International Nuclear Information System (INIS)

    Frenet, D.

    2000-01-01

    In this document we present a theoretical and experimental study which has been led to design a surface acoustic wave device for local characterisation (relatively to the wavelength) of isotropic or anisotropic materials. The device is based on a phased-array transducer of conical shape we have specifically designed for this purpose. It operates in the impulsive mode, in the frequency range of 1-5 MHz. In order to deduce mechanical properties of the material, it is possible to measure the surface wave characteristics (velocity, attenuation,...). Different methods for measuring the wave velocity have been developed taking advantage of from the phased-array technology. The originality of theses methods relies on the fact that the measures are performed without moving the transducer. Consequently, the device requires no additional mechanical system and it is quite compact. In addition, this shortens the characterisation process duration comparatively to the usually available methods (e. g. the V(z) technique). In the theoretical section of this study, a versatile model allowing to simulate in the time harmonic regime as well as in the transient regime, the transmitted field, the field reflected on isotropic or anisotropic planar samples and the output voltage for transducers of arbitrary shapes has been developed. The model has been applied to the phased-array conical transducer as well as to more classical transducers such as planar (rectangular) or focusing (spherically or cylindrically shaped) transducers. It predicts not only the geometrical contributions of the reflected field and signal but also the leaky contributions related to the surface acoustic waves. (author)

  12. Laser method of acoustical emission control from vibrating surfaces

    Science.gov (United States)

    Motyka, Zbigniew

    2013-01-01

    For limitation of the noise in environment, the necessity occurs of determining and location of sources of sounds emitted from surfaces of many machines and devices, assuring in effect the possibility of suitable constructional changes implementation, targeted at decreasing of their nuisance. In the paper, the results of tests and calculations are presented for plane surface sources emitting acoustic waves. The tests were realized with the use of scanning laser vibrometer which enabled remote registration and the spectral analysis of the surfaces vibrations. The known hybrid digital method developed for determination of sound wave emission from such surfaces divided into small finite elements was slightly modified by distinguishing the phase correlations between such vibrating elements. The final method being developed may find use in wide range of applications for different forms of vibrations of plane surfaces.

  13. Flat acoustic lens by acoustic grating with curled slits

    KAUST Repository

    Peng, Pai

    2014-10-01

    We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry-Perot resonance.

  14. Large scale modulation of high frequency acoustic waves in periodic porous media.

    Science.gov (United States)

    Boutin, Claude; Rallu, Antoine; Hans, Stephane

    2012-12-01

    This paper deals with the description of the modulation at large scale of high frequency acoustic waves in gas saturated periodic porous media. High frequencies mean local dynamics at the pore scale and therefore absence of scale separation in the usual sense of homogenization. However, although the pressure is spatially varying in the pores (according to periodic eigenmodes), the mode amplitude can present a large scale modulation, thereby introducing another type of scale separation to which the asymptotic multi-scale procedure applies. The approach is first presented on a periodic network of inter-connected Helmholtz resonators. The equations governing the modulations carried by periodic eigenmodes, at frequencies close to their eigenfrequency, are derived. The number of cells on which the carrying periodic mode is defined is therefore a parameter of the modeling. In a second part, the asymptotic approach is developed for periodic porous media saturated by a perfect gas. Using the "multicells" periodic condition, one obtains the family of equations governing the amplitude modulation at large scale of high frequency waves. The significant difference between modulations of simple and multiple mode are evidenced and discussed. The features of the modulation (anisotropy, width of frequency band) are also analyzed.

  15. Dynamics of acoustically levitated disk samples.

    Science.gov (United States)

    Xie, W J; Wei, B

    2004-10-01

    The acoustic levitation force on disk samples and the dynamics of large water drops in a planar standing wave are studied by solving the acoustic scattering problem through incorporating the boundary element method. The dependence of levitation force amplitude on the equivalent radius R of disks deviates seriously from the R3 law predicted by King's theory, and a larger force can be obtained for thin disks. When the disk aspect ratio gamma is larger than a critical value gamma(*) ( approximately 1.9 ) and the disk radius a is smaller than the critical value a(*) (gamma) , the levitation force per unit volume of the sample will increase with the enlargement of the disk. The acoustic levitation force on thin-disk samples ( gammaacoustic field for stable levitation of a large water drop is to adjust the reflector-emitter interval H slightly above the resonant interval H(n) . The simulation shows that the drop is flattened and the central parts of its top and bottom surface become concave with the increase of sound pressure level, which agrees with the experimental observation. The main frequencies of the shape oscillation under different sound pressures are slightly larger than the Rayleigh frequency because of the large shape deformation. The simulated translational frequencies of the vertical vibration under normal gravity condition agree with the theoretical analysis.

  16. A frequency domain linearized Navier-Stokes method including acoustic damping by eddy viscosity using RANS

    Science.gov (United States)

    Holmberg, Andreas; Kierkegaard, Axel; Weng, Chenyang

    2015-06-01

    In this paper, a method for including damping of acoustic energy in regions of strong turbulence is derived for a linearized Navier-Stokes method in the frequency domain. The proposed method is validated and analyzed in 2D only, although the formulation is fully presented in 3D. The result is applied in a study of the linear interaction between the acoustic and the hydrodynamic field in a 2D T-junction, subject to grazing flow at Mach 0.1. Part of the acoustic energy at the upstream edge of the junction is shed as harmonically oscillating disturbances, which are conveyed across the shear layer over the junction, where they interact with the acoustic field. As the acoustic waves travel in regions of strong shear, there is a need to include the interaction between the background turbulence and the acoustic field. For this purpose, the oscillation of the background turbulence Reynold's stress, due to the acoustic field, is modeled using an eddy Newtonian model assumption. The time averaged flow is first solved for using RANS along with a k-ε turbulence model. The spatially varying turbulent eddy viscosity is then added to the spatially invariant kinematic viscosity in the acoustic set of equations. The response of the 2D T-junction to an incident acoustic field is analyzed via a plane wave scattering matrix model, and the result is compared to experimental data for a T-junction of rectangular ducts. A strong improvement in the agreement between calculation and experimental data is found when the modification proposed in this paper is implemented. Discrepancies remaining are likely due to inaccuracies in the selected turbulence model, which is known to produce large errors e.g. for flows with significant rotation, which the grazing flow across the T-junction certainly is. A natural next step is therefore to test the proposed methodology together with more sophisticated turbulence models.

  17. Material Property Measurement in Hostile Environments using Laser Acoustics

    International Nuclear Information System (INIS)

    Ken L. Telschow

    2004-01-01

    Acoustic methods are well known and have been used to measure various intrinsic material properties, such as, elastic coefficients, density, crystal axis orientation, microstructural texture, and residual stress. Extrinsic properties, such as, dimensions, motion variables or temperature are also readily determined from acoustic methods. Laser acoustics, employing optical generation and detection of elastic waves, has a unique advantage over other acoustic methods-it is noncontacting, uses the sample surface itself for transduction, requires no couplant or invasive sample surface preparation and can be utilized in any hostile environment allowing optical access to the sample surface. In addition, optical generation and detection probe beams can be focused to the micron scale and/or shaped to alter the transduction process with a degree of control not possible using contact transduction methods. Laser methods are amenable to both continuous wave and pulse-echo measurements and have been used from Hz to 100's of GHz (time scales from sec to psec) and with amplitudes sufficient to fracture materials. This paper shall review recent applications of laser acoustic methods to determining material properties in hostile environments that preclude the use of contacting transduction techniques. Example environments include high temperature (>1000C) sintering and molten metal processing, thin film deposition by plasma techniques, materials moving at high velocity during the fabrication process and nuclear high radiation regions. Recent technological advances in solid-state lasers and telecommunications have greatly aided the development and implementation of laser acoustic methods, particularly at ultra high frequencies. Consequently, laser acoustic material property measurements exhibit high precision and reproducibility today. In addition, optical techniques provide methods of imaging acoustic motion that is both quantitative and rapid. Possible future directions for laser

  18. Modeling of Acoustic Field for a Parametric Focusing Source Using the Spheroidal Beam Equation

    Directory of Open Access Journals (Sweden)

    Yu Lili

    2015-09-01

    Full Text Available A theoretical model of acoustic field for a parametric focusing source on concave spherical surface is proposed. In this model, the source boundary conditions of the Spheroidal Beam Equation (SBE for difference frequency wave excitation were studied. Propagation curves and beam patterns for difference frequency component of the acoustic field are compared with those obtained for Khokhlov-Zabolotskaya-Kuznetsov (KZK model. The results demonstrate that the focused parametric model of SBE is good valid for a large aperture angle in the strongly focused acoustic field. It is also investigated that high directivity and good focal ability with the decreasing of downshift ratio and the increasing of half-aperture angle for the focused parametric model of SBE.

  19. Acoustic receptivity and transition modeling of Tollmien-Schlichting disturbances induced by distributed surface roughness

    Science.gov (United States)

    Raposo, Henrique; Mughal, Shahid; Ashworth, Richard

    2018-04-01

    Acoustic receptivity to Tollmien-Schlichting waves in the presence of surface roughness is investigated for a flat plate boundary layer using the time-harmonic incompressible linearized Navier-Stokes equations. It is shown to be an accurate and efficient means of predicting receptivity amplitudes and, therefore, to be more suitable for parametric investigations than other approaches with direct-numerical-simulation-like accuracy. Comparison with the literature provides strong evidence of the correctness of the approach, including the ability to quantify non-parallel flow effects. These effects are found to be small for the efficiency function over a wide range of frequencies and local Reynolds numbers. In the presence of a two-dimensional wavy-wall, non-parallel flow effects are quite significant, producing both wavenumber detuning and an increase in maximum amplitude. However, a smaller influence is observed when considering an oblique Tollmien-Schlichting wave. This is explained by considering the non-parallel effects on receptivity and on linear growth which may, under certain conditions, cancel each other out. Ultimately, we undertake a Monte Carlo type uncertainty quantification analysis with two-dimensional distributed random roughness. Its power spectral density (PSD) is assumed to follow a power law with an associated uncertainty following a probabilistic Gaussian distribution. The effects of the acoustic frequency over the mean amplitude of the generated two-dimensional Tollmien-Schlichting waves are studied. A strong dependence on the mean PSD shape is observed and discussed according to the basic resonance mechanisms leading to receptivity. The growth of Tollmien-Schlichting waves is predicted with non-linear parabolized stability equations computations to assess the effects of stochasticity in transition location.

  20. Evaluation of the sensitivity of electro-acoustic measurements for process monitoring and control of an atmospheric pressure plasma jet system

    Energy Technology Data Exchange (ETDEWEB)

    Law, V J [Dublin City University, National Centre of Plasma Science and Technology, Collins Avenue, Glasnevin, Dublin 9, Dublin (Ireland); O' Neill, F T; Dowling, D P, E-mail: vic.law@dcu.ie [School Mechanical and Materials Engineering, University College Dublin, Belfield, Dublin 4 (Ireland)

    2011-06-15

    The development of non-invasive process diagnostic techniques for the control of atmospheric plasmas is a critical issue for the wider adoption of this technology. This paper evaluates the use of a frequency-domain deconvolution of an electro-acoustic emission as a means to monitor and control the plasma formed using an atmospheric pressure plasma jet (APPJ) system. The air plasma system investigated was formed using a PlasmaTreat(TM) OpenAir applicator. Change was observed in the electro-acoustic signal with changes in substrate type (ceramic, steel, polymer). APPJ nozzle to substrate distance and substrate feature size were monitored. The decoding of the electro-acoustic emission yields three subdatasets that are described by three separate emission mechanisms. The three emissions are associated with the power supply fundamental drive frequency and its harmonics, the APPJ nozzle longitudinal mode acoustic emission and its odd overtones, and the acoustic surface reflection that is produced by the impedance mismatch between the discharge and the surface. Incorporating this knowledge into a LabVIEW program facilitated the continuous deconvolution of the electro-acoustic data. This enabled the use of specific frequency band test limits to control the APPJ treatment process which is sensitive to both plasma processing conditions and substrate type and features.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-10

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

  2. Acoustic study of YBa2Cu3Ox thin films

    International Nuclear Information System (INIS)

    Lee, S.; Chi, C.; Koren, G.; Gupta, A.

    1991-01-01

    The attenuation of surface acoustic waves by epitaxial YBa 2 Cu 3 O x films has been studied for x congruent 6 to 7. For fully oxygenated samples, the acoustic attenuation as a function of temperature shows two broad peaks at about 135 and 240 K, and decreases monotonically below the lower peak temperature. The cause of attenuation peaks is attributed to scattering by optical phonons. Our data do not show any gap structure at T c due to relatively weak electron-phonon interactions at the acoustic frequencies. As the oxygen deficiency increases, the temperature dependence of the dc resistance changes from metallic to semiconducting and finally to insulating behavior. Acoustic attenuation data correspondingly show a drastic change due to different attenuation mechanisms: from the phonon scattering loss in the metallic regime to the electric-field coupling loss in the semiconducting and insulating regimes. In the latter regimes, the temperature dependence of low-frequency resistance calculated from the attenuation data can be fitted to a three-dimensional Mott variable-range-hopping model

  3. Hidden acoustic information revealed by intentional nonlinearity

    Science.gov (United States)

    Dowling, David R.

    2017-11-01

    Acoustic waves are omnipresent in modern life and are well described by the linearized equations of fluid dynamics. Once generated, acoustic waves carry and collect information about their source and the environment through which they propagate, respectively, and this information may be retrieved by analyzing recordings of these waves. Because of this, acoustics is the primary means for observation, surveillance, reconnaissance, and remote sensing in otherwise opaque environments, such as the Earth's oceans and crust, and the interior of the human body. For such information-retrieval tasks, acoustic fields are nearly always interrogated within their recorded frequency range or bandwidth. However, this frequency-range restriction is not general; acoustic fields may also carry (hidden) information at frequencies outside their bandwidth. Although such a claim may seem counter intuitive, hidden acoustic-field information can be revealed by re-introducing a marquee trait of fluid dynamics: nonlinearity. In particular, an intentional quadratic nonlinearity - a form of intra-signal heterodyning - can be used to obtain acoustic field information at frequencies outside a recorded acoustic field's bandwidth. This quadratic nonlinearity enables a variety of acoustic remote sensing applications that were long thought to be impossible. In particular, it allows the detrimental effects of sparse recordings and random scattering to be suppressed when the original acoustic field has sufficient bandwidth. In this presentation, the topic is developed heuristically, with a just brief exposition of the relevant mathematics. Hidden acoustic field information is then revealed from simulated and measured acoustic fields in simple and complicated acoustic environments involving frequencies from a few Hertz to more than 100 kHz, and propagation distances from tens of centimeters to hundreds of kilometers. Sponsored by ONR, NAVSEA, and NSF.

  4. Low frequency acoustic waves from explosive sources in the atmosphere

    Science.gov (United States)

    Millet, Christophe; Robinet, Jean-Christophe; Roblin, Camille; Gloerfelt, Xavier

    2006-11-01

    In this study, a perturbative formulation of non linear euler equations is used to compute the pressure variation for low frequency acoustic waves from explosive sources in real atmospheres. Based on a Dispersion-Relation-Preserving (DRP) finite difference scheme, the discretization provides good properties for both sound generation and long range sound propagation over a variety of spatial atmospheric scales. It also assures that there is no wave mode coupling in the numerical simulation The background flow is obtained by matching the comprehensive empirical global model of horizontal winds HWM-93 (and MSISE-90 for the temperature profile) with meteorological reanalysis of the lower atmosphere. Benchmark calculations representing cases where there is downward and upward refraction (including shadow zones), ducted propagation, and generation of acoustic waves from low speed shear layers are considered for validation. For all cases, results show a very good agreement with analytical solutions, when available, and with other standard approaches, such as the ray tracing and the normal mode technique. Comparison of calculations and experimental data from the high explosive ``Misty Picture'' test that provided the scaled equivalent airblast of an 8 kt nuclear device (on May 14, 1987), is also considered. It is found that instability waves develop less than one hour after the wavefront generated by the detonation passes.

  5. An experimental modeling and acoustic emission monitoring of abrasive wear in a steel/diabase pair

    Science.gov (United States)

    Korchuganov, M. A.; Filippov, A. V.; Tarasov, S. Yu.; Podgornyh, O. A.; Shamarin, N. N.; Filippova, E. O.

    2016-11-01

    The earthmoving of permafrost soil is a critical task for excavation of minerals and construction on new territories. Failure by abrasive wear is the main reason for excavation parts of earthmoving and soil cutting machines. Therefore investigation of this type of wear is a challenge for developing efficient and wear resistant working parts. This paper is focused on conducting tribological experiments with sliding the steel samples over the surface of diabase stone sample where abrasive wear conditions of soil cutting are modeled experimentally. The worn surfaces of all samples have been examined and transfer of metal and stone particles revealed. The acoustic emission (AE) signals have been recorded and related to the results of worn surface analysis. he acoustic emission (AE) signals have been recorded and related to the results of worn surface analysis. As shown the wear intensity correlates to that of acoustic emission. Both acoustic emission signal median frequency and energy are found to be sensitive to the wear mode.

  6. Validation of a Phase-Mass Characterization Concept and Interface for Acoustic Biosensors

    Directory of Open Access Journals (Sweden)

    Antonio Arnau

    2011-04-01

    Full Text Available Acoustic wave resonator techniques are widely used in in-liquid biochemical applications. The main challenges remaining are the improvement of sensitivity and limit of detection, as well as multianalysis capabilities and reliability. The sensitivity improvement issue has been addressed by increasing the sensor frequency, using different techniques such as high fundamental frequency quartz crystal microbalances (QCMs, surface generated acoustic waves (SGAWs and film bulk acoustic resonators (FBARs. However, this sensitivity improvement has not been completely matched in terms of limit of detection. The decrease on frequency stability due to the increase of the phase noise, particularly in oscillators, has made it impossible to increase the resolution. A new concept of sensor characterization at constant frequency has been recently proposed based on the phase/mass sensitivity equation: ∆φ/∆m ≈ −1/mL, where mL is the liquid mass perturbed by the resonator. The validation of the new concept is presented in this article. An immunosensor application for the detection of a low molecular weight pollutant, the insecticide carbaryl, has been chosen as a validation model.

  7. Quantitative measurement of local elasticity of SiOx film by atomic force acoustic microscopy

    International Nuclear Information System (INIS)

    Cun-Fu, He; Gai-Mei, Zhang; Bin, Wu

    2010-01-01

    In this paper the elastic properties of SiO x film are investigated quantitatively for local fixed point and qualitatively for overall area by atomic force acoustic microscopy (AFAM) in which the sample is vibrated at the ultrasonic frequency while the sample surface is touched and scanned with the tip contacting the sample respectively for fixed point and continuous measurements. The SiO x films on the silicon wafers are prepared by the plasma enhanced chemical vapour deposition (PECVD). The local contact stiffness of the tip-SiO x film is calculated from the contact resonance spectrum measured with the atomic force acoustic microscopy. Using the reference approach, indentation modulus of SiO x film for fixed point is obtained. The images of cantilever amplitude are also visualized and analysed when the SiO x surface is excited at a fixed frequency. The results show that the acoustic amplitude images can reflect the elastic properties of the sample. (classical areas of phenomenology)

  8. Acoustic feedwater heater leak detection: Industry application of low ampersand high frequency detection increases response and reliability

    International Nuclear Information System (INIS)

    Woyshner, W.S.; Bryson, T.; Robertson, M.O.

    1993-01-01

    The Electric Power Research Institute has sponsored research associated with acoustic Feedwater Heater Leak Detection since the early 1980s. Results indicate that this technology is economically beneficial and dependable. Recent research work has employed acoustic sensors and signal conditioning with wider frequency range response and background noise elimination techniques to provide increased accuracy and dependability. Dual frequency sensors have been applied at a few facilities to provide information on this application of dual frequency response. Sensor mounting methods and attenuation due to various mounting configurations are more conclusively understood. These are depicted and discussed in detail. The significance of trending certain plant parameters such as heat cycle flows, heater vent and drain valve position, proper relief valve operation, etc. is also addressed. Test data were collected at various facilities to monitor the effect of varying several related operational parameters. A group of FWHLD Users have been involved from the inception of the project and reports on their latest successes and failures, along with various data depicting early detection of FWHLD tube leaks, will be included. 3 refs., 12 figs., 1 tab

  9. Optimization of Dimensions of Cylindrical Piezoceramics as Radio-Clean Low Frequency Acoustic Sensors

    Directory of Open Access Journals (Sweden)

    M. Ardid

    2017-01-01

    Full Text Available Circular piezoelectric transducers with axial polarization are proposed as low frequency acoustic sensors for dark matter bubble chamber detectors. The axial vibration behaviour of the transducer is studied by three different methods: analytical models, FEM simulation, and experimental setup. To optimize disk geometry for this application, the dependence of the vibrational modes in function of the diameter-to-thickness ratio from 0.5 (a tall cylinder to 20.0 (a thin disk has been studied. Resonant and antiresonant frequencies for each of the lowest modes are determined and electromechanical coupling coefficients are calculated. From this analysis, due to the requirements of radiopurity and little volume, optimal diameter-to-thickness ratios for good transducer performance are discussed.

  10. Frequency and magnetic field mapping of magnetoelastic spin pumping in high overtone bulk acoustic wave resonator

    Science.gov (United States)

    Polzikova, N. I.; Alekseev, S. G.; Pyataikin, I. I.; Luzanov, V. A.; Raevskiy, A. O.; Kotov, V. A.

    2018-05-01

    We report on the first observation of microvolt-scale inverse spin Hall effect (ISHE) dc voltage driven by an acoustic spin pumping (ASP) in a bulk acoustic wave (BAW) resonator formed by a Al-ZnO-Al-YIG(1)-GGG-YIG(2)-Pt structure. When 2 mW power is applied to an Al-ZnO-Al transducer, the voltage VISHE ˜ 4 μV in the Pt film is observed as a result of resonant ASP from YIG(2) to Pt in the area ˜ 170 μm. The results of frequency and magnetic field mapping of VISHE(f,H) together with reflectivity of the resonator show an obvious agreement between the positions of the voltage maxima and BAW resonance frequencies fn(H) on the (f, H) plane. At the same time a significant asymmetry of the VISHE(fn(H)) value in reference to the magnetoelastic resonance (MER) line fMER(H) position is revealed, which is explained by asymmetry of the magnetoelastic waves dispersion law.

  11. Polyvinylpyrrolidone/ Poly aniline Composite Based 36 degree YX LiTaO3 Surface Acoustic Wave H2 Gas Sensor

    International Nuclear Information System (INIS)

    Amir Sidek; Rashidah Arsat; Xiuli, He; Kalantar-zadeh, K.; Wlodarski, W.

    2013-01-01

    Poly-vinyl-pyrrolidone (PVP)/ poly aniline based surface acoustic wave (SAW) sensors were fabricated and characterized and their performances towards hydrogen gas were investigated. The PVP/ poly aniline fibers composite were prepared by electro spinning of the composite aqueous solution deposited directly onto the active area of SAW transducers. Via scanning electron microscopy (SEM), the morphology of the deposited nano structure material was observed. From the dynamic response, frequency shifts of 6.243 kHz (1% H 2 ) and 8.051 kHz (1% H 2 ) were recorded for the sensors deposited with PVP/ ES and PVP/ EB, respectively. (author)

  12. Acoustic field generated by flight of rocket at the Earth surface

    International Nuclear Information System (INIS)

    Drobzheva, Ya.V.; Krasnov, V.M.; Maslov, A.N.

    2006-01-01

    In this paper we present a model, which describes the propagation of acoustic impulses produced by explosion of carrier rocket at the active part of trajectory, down through the atmosphere. Calculations of acoustic field parameters on the earth surface were made for altitudes of rocket flight from 2.8 to 92.3 km and yield of explosions from 0.001 to 0.5 t tnt. It was shown the infrasound accompaniment of rocket flight with the goal to register the explosion it is possible only for an altitude about 70 km. For this case, test set should be situated at the distance not exceeding 120 km from the starting place. (author)

  13. Acousto-plasmofluidics: Acoustic modulation of surface plasmon resonance in microfluidic systems

    Directory of Open Access Journals (Sweden)

    Daniel Ahmed

    2015-09-01

    Full Text Available We acoustically modulated the localized surface plasmon resonances (LSPRs of metal nanostructures integrated within microfluidic systems. An acoustically driven micromixing device based on bubble microstreaming quickly and homogeneously mixes multiple laminar flows of different refractive indices. The altered refractive index of the mixed fluids enables rapid modulation of the LSPRs of gold nanodisk arrays embedded within the microfluidic channel. The device features fast response for dynamic operation, and the refractive index within the channel is tailorable. With these unique features, our “acousto-plasmofluidic” device can be useful in applications such as optical switches, modulators, filters, biosensors, and lab-on-a-chip systems.

  14. Qualitative internal surface roughness classification using acoustic emission

    International Nuclear Information System (INIS)

    Mohd Hafizi Zohari; Mohd Hanif Saad

    2009-04-01

    This paper describes a novel new nondestructive method of qualitative internal surface roughness classification for pipes utilizing Acoustic Emission (AE) signal. Two different flowrate are introduced in a pipe obstructed using normally available components (e.g.: valve). The AE signal at suitable location from the obstruction are obtained and the peak amplitudes, RMS amplitude and energy of the AE signal are obtained. A dimensionless number, the Bangi Number, AB, is then calculated as a ratio of the AE parameters (peak amplitude, RMS amplitude or energy) in low flowrate measurement compared to the AE parameters in high flowrate measurement. It was observed that the Bangi Number, AB obtained can then be used to successfully discriminate between rough and smooth internal surface roughness. (author)

  15. The influence of acoustic field and frequency on Hydrodynamics of Group B particles

    Directory of Open Access Journals (Sweden)

    R L Sonolikar

    2011-01-01

    Full Text Available Sound Assisted Fluidized Bed (SAFB of group B particles (180μm glass bead has been studied in a 46mm I.D. column with aspect ratios of 1.4 and 2.9. A loudspeaker mounted on the top of the bed was supplied by a function generator with square wave to generate the sound as the source of vibration of the fluidized bed. The sound pressure level (referred to 20μpa was varied from 102 to 140dB and frequencies from 70Hz to 170Hz were applied. The effects of sound pressure level, sound frequency and particle loading on the properties of SAFB were investigated. The experimental result showed that the minimum fluidization velocity decreased with the increase in sound pressure level, also minimum fluidization velocity was varied with variation of frequencies. At resonance frequency minimum fluidization velocity was found to be minimum. The bed height did not show an appreciable increase in presence of high acoustic field and at resonant frequency. Minimum fluidization velocity verses frequency curve in presence of sound intensity varied with variation of bed weight.

  16. Analytical Model of the Nonlinear Dynamics of Cantilever Tip-Sample Surface Interactions for Various Acoustic-Atomic Force Microscopies

    Science.gov (United States)

    Cantrell, John H., Jr.; Cantrell, Sean A.

    2008-01-01

    A comprehensive analytical model of the interaction of the cantilever tip of the atomic force microscope (AFM) with the sample surface is developed that accounts for the nonlinearity of the tip-surface interaction force. The interaction is modeled as a nonlinear spring coupled at opposite ends to linear springs representing cantilever and sample surface oscillators. The model leads to a pair of coupled nonlinear differential equations that are solved analytically using a standard iteration procedure. Solutions are obtained for the phase and amplitude signals generated by various acoustic-atomic force microscope (A-AFM) techniques including force modulation microscopy, atomic force acoustic microscopy, ultrasonic force microscopy, heterodyne force microscopy, resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), and the commonly used intermittent contact mode (TappingMode) generally available on AFMs. The solutions are used to obtain a quantitative measure of image contrast resulting from variations in the Young modulus of the sample for the amplitude and phase images generated by the A-AFM techniques. Application of the model to RDF-AFUM and intermittent soft contact phase images of LaRC-cp2 polyimide polymer is discussed. The model predicts variations in the Young modulus of the material of 24 percent from the RDF-AFUM image and 18 percent from the intermittent soft contact image. Both predictions are in good agreement with the literature value of 21 percent obtained from independent, macroscopic measurements of sheet polymer material.

  17. Shallow water acoustic backscatter and reverberation measurements using a 68-kHz cylindrical array: a dissertation

    OpenAIRE

    Gallaudet, Timothy C. (Timothy Cole), 1967-

    2001-01-01

    The characterization of high frequency, shallow water acoustic backscatter and reverberation is important because acoustic systems are used in many scientific, commercial, and military applications. The approach taken is to use data collected by the Toroidal Volume Search Sonar (TVSS), a 68 kHz multibeam sonar capable of 360 deg imaging in a vertical plane perpendicular to its direction of travel. With this unique capability, acoustic backscatter imagery of the seafloor, sea surface, and hori...

  18. Sinusoidal Representation of Acoustic Signals

    Science.gov (United States)

    Honda, Masaaki

    Sinusoidal representation of acoustic signals has been an important tool in speech and music processing like signal analysis, synthesis and time scale or pitch modifications. It can be applicable to arbitrary signals, which is an important advantage over other signal representations like physical modeling of acoustic signals. In sinusoidal representation, acoustic signals are composed as sums of sinusoid (sine wave) with different amplitudes, frequencies and phases, which is based on the timedependent short-time Fourier transform (STFT). This article describes the principles of acoustic signal analysis/synthesis based on a sinusoid representation with focus on sine waves with rapidly varying frequency.

  19. Electron/electron acoustic instability

    International Nuclear Information System (INIS)

    Gary, S.P.

    1987-01-01

    The electron acoustic wave becomes a normal mode of an unmagnetized collisionless plasma in the presence of two electron components with similar densities, but strongly disparate temperatures. The characteristic frequency of this mode is the plasma frequency of the cooler electron component. If these two electron components have a relative drift speed several times the thermal speed of the cooler component, the electron/electron acoustic instability may arise. This paper describes the parametric dependences of the threshold drift speed and maximum growth rate of this instability, and compares these with the same properties of the electron/ion acoustic instability. Under the condition of zero current, the electron/ion acoustic instability typically has the lower threshold drift speed, so that observation of the electron/electron acoustic instability is a strong indication of the presence of an electrical current in the plasma

  20. Preliminary study of the effect of the turbulent flow field around complex surfaces on their acoustic characteristics

    Science.gov (United States)

    Olsen, W. A.; Boldman, D.

    1978-01-01

    Fairly extensive measurements have been conducted of the turbulent flow around various surfaces as a basis for a study of the acoustic characteristics involved. In the experiments the flow from a nozzle was directed upon various two-dimensional surface configurations such as the three-flap model. A turbulent flow field description is given and an estimate of the acoustic characteristics is provided. The developed equations are based upon fundamental theories for simple configurations having simple flows. Qualitative estimates are obtained regarding the radiation pattern and the velocity power law. The effect of geometry and turbulent flow distribution on the acoustic emission from simple configurations are discussed.

  1. An oxygen pressure sensor using surface acoustic wave devices

    Science.gov (United States)

    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.

  2. Surface acoustic waves and elastic constants of InN epilayers determined by Brillouin scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Rioboo, R.J.; Prieto, C. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, Madrid (Spain); Cusco, R.; Domenech-Amador, N.; Artus, L. [Institut Jaume Almera, Consell Superior d' Investigacions Cientifiques (CSIC), Lluis Sole i Sabaris s.n., Barcelona, Catalonia (Spain); Yamaguchi, T.; Nanishi, Y. [Faculty of Science and Engineering, Ritsumeikan University, Noji-Higashi, Kusatsu, Shiga (Japan)

    2012-06-15

    The surface acoustic wave velocity in InN has been experimentally determined by means of Brillouin scattering experiments on c - and m -face epilayers. From simulations based on the Green's function formalism we determine the shear elastic constants c{sub 66} and c{sub 44} and propose a complete set of elastic constants for wurtzite InN. The analysis of the sagittal and azimuthal dependence of the surface acoustic wave velocity indicates a slightly different elastic behavior of the m -face sample that basically affects the c{sub 44} elastic constant. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. A surface acoustic wave humidity sensor with high sensitivity based on electrospun MWCNT/Nafion nanofiber films

    International Nuclear Information System (INIS)

    Lei Sheng; Chen Dajing; Chen Yuquan

    2011-01-01

    Humidity detection has been widely used in a variety of fields. A humidity sensor with high sensitivity is reported in this paper. A surface acoustic wave resonator (SAWR) with high resonance frequency was fabricated as a basic sensitive component. Various nanotechnologies were used to improve the sensor's performance. A multi-walled carbon nanotube/Nafion (MWCNT/Nafion) composite material was prepared as humidity-sensitive films, deposited on the surface of an SAWR by the electrospinning method. The electrospun MWCNT/Nafion nanofiber films showed a three-dimensional (3D) porous structure, which was profitable for improving the sensor's performance. The new nano-water-channel model of Nafion was also applied in the humidity sensing process. Compared to other research, the present sensor showed excellent sensitivity (above 400 kHz/% relative humidity (RH) in the range from 10% RH to 80% RH), good linearity (R 2 > 0.98) and a short response time (∼3 s-63%).

  4. Calculation of acoustic field based on laser-measured vibration velocities on ultrasonic transducer surface

    Science.gov (United States)

    Hu, Liang; Zhao, Nannan; Gao, Zhijian; Mao, Kai; Chen, Wenyu; Fu, Xin

    2018-05-01

    Determination of the distribution of a generated acoustic field is valuable for studying ultrasonic transducers, including providing the guidance for transducer design and the basis for analyzing their performance, etc. A method calculating the acoustic field based on laser-measured vibration velocities on the ultrasonic transducer surface is proposed in this paper. Without knowing the inner structure of the transducer, the acoustic field outside it can be calculated by solving the governing partial differential equation (PDE) of the field based on the specified boundary conditions (BCs). In our study, the BC on the transducer surface, i.e. the distribution of the vibration velocity on the surface, is accurately determined by laser scanning measurement of discrete points and follows a data fitting computation. In addition, to ensure the calculation accuracy for the whole field even in an inhomogeneous medium, a finite element method is used to solve the governing PDE based on the mixed BCs, including the discretely measured velocity data and other specified BCs. The method is firstly validated on numerical piezoelectric transducer models. The acoustic pressure distributions generated by a transducer operating in an homogeneous and inhomogeneous medium, respectively, are both calculated by the proposed method and compared with the results from other existing methods. Then, the method is further experimentally validated with two actual ultrasonic transducers used for flow measurement in our lab. The amplitude change of the output voltage signal from the receiver transducer due to changing the relative position of the two transducers is calculated by the proposed method and compared with the experimental data. This method can also provide the basis for complex multi-physical coupling computations where the effect of the acoustic field should be taken into account.

  5. Acoustic Pressure Waves in Vibrating 3-D Laminated Beam-Plate Enclosures

    Directory of Open Access Journals (Sweden)

    Charles A. Osheku

    2009-01-01

    Full Text Available The effect of structural vibration on the propagation of acoustic pressure waves through a cantilevered 3-D laminated beam-plate enclosure is investigated analytically. For this problem, a set of well-posed partial differential equations governing the vibroacoustic wave interaction phenomenon are formulated and matched for the various vibrating boundary surfaces. By employing integral transforms, a closed form analytical expression is computed suitable for vibroacoustic modeling, design analysis, and general aerospace defensive applications. The closed-form expression takes the form of a kernel of polynomials for acoustic pressure waves showing the influence of linear interface pressure variation across the axes of vibrating boundary surfaces. Simulated results demonstrate how the mode shapes and the associated natural frequencies can be easily computed. It is shown in this paper that acoustic pressure waves propagation are dynamically stable through laminated enclosures with progressive decrement in interfacial pressure distribution under the influence of high excitation frequencies irrespective of whether the induced flow is subsonic, sonic , supersonic, or hypersonic. Hence, in practice, dynamic stability of hypersonic aircrafts or jet airplanes can be further enhanced by replacing their noise transmission systems with laminated enclosures.

  6. NEAR- AND FAR-FIELD RESPONSE TO COMPACT ACOUSTIC SOURCES IN STRATIFIED CONVECTION ZONES

    International Nuclear Information System (INIS)

    Cally, Paul S.

    2013-01-01

    The role of the acoustic continuum associated with compact sources in the Sun's interior wave field is explored for a simple polytropic model. The continuum produces a near-field acoustic structure—the so-called acoustic jacket—that cannot be represented by a superposition of discrete normal modes. Particular attention is paid to monochromatic point sources of various frequency and depth, and to the surface velocity power that results, both in the discrete f- and p-mode spectrum and in the continuum. It is shown that a major effect of the continuum is to heal the surface wave field produced by compact sources, and therefore to hide them from view. It is found that the continuous spectrum is not a significant contributor to observable inter-ridge seismic power.

  7. Surface acoustic wave solid-state rotational micromotor

    Science.gov (United States)

    Shilton, Richie J.; Langelier, Sean M.; Friend, James R.; Yeo, Leslie Y.

    2012-01-01

    Surface acoustic waves (SAWs) are used to drive a 1 mm diameter rotor at speeds exceeding 9000 rpm and torque of nearly 5 nNm. Unlike recent high-speed SAW rotary motors, however, the present design does not require a fluid coupling layer but interestingly exploits adhesive stiction as an internal preload, a force usually undesirable at these scales; with additional preloads, smaller rotors can be propelled to 15 000 rpm. This solid-state motor has no moving parts except for the rotor and is sufficiently simple to allow integration into miniaturized drive systems for potential use in microfluidic diagnostics, optical switching and microrobotics.

  8. Characterization of low-frequency acoustic wave propagation through a periodic corrugated waveguide

    Science.gov (United States)

    Jiang, Changyong; Huang, Lixi

    2018-03-01

    In this paper, a periodic corrugated waveguide structure is proposed, and its unit-cell is analyzed by the wave finite element method. In low-frequency range, the unit-cell is treated as an equivalent fluid through a homogenization process, and the equivalent acoustic parameters are obtained, which are validated by finite structure simulations and experiments. The proposed structure is shown to add tortuosity to the waveguide, hence higher equivalent fluid density is achieved, while the system elastic modulus remains unchanged. As a result, the equivalent speed of sound is smaller than normal air. The application of such change of speed of sound is demonstrated in the classic quarter-wavelength resonator based on the corrugated waveguide, which gives a lower resonance frequency with the same side branch length. When the waveguide is filled with porous materials, the added tortuosity enhances the broadband, low-frequency sound absorption by increasing the equivalent mass without bringing in excess damping, the latter being partly responsible for the poor performance of usual porous materials in the low-frequency region. Therefore, the proposed structure provides another dimension for the design and optimization of porous sound absorption materials.

  9. Theoretical Model of Acoustic Wave Propagation in Shallow Water

    Directory of Open Access Journals (Sweden)

    Kozaczka Eugeniusz

    2017-06-01

    Full Text Available The work is devoted to the propagation of low frequency waves in a shallow sea. As a source of acoustic waves, underwater disturbances generated by ships were adopted. A specific feature of the propagation of acoustic waves in shallow water is the proximity of boundaries of the limiting media characterised by different impedance properties, which affects the acoustic field coming from a source situated in the water layer “deformed” by different phenomena. The acoustic field distribution in the real shallow sea is affected not only by multiple reflections, but also by stochastic changes in the free surface shape, and statistical changes in the seabed shape and impedance. The paper discusses fundamental problems of modal sound propagation in the water layer over different types of bottom sediments. The basic task in this case was to determine the acoustic pressure level as a function of distance and depth. The results of the conducted investigation can be useful in indirect determination of the type of bottom.

  10. Detection of defects and evaluation of material deterioration using surface wave technique

    International Nuclear Information System (INIS)

    Yokono, Yoshikazu; Yoshiara, Toshikatsu; Suetsugu, Jun; Imanaka, Takuichi

    1996-01-01

    It is very important to detect surface damage and evaluate deterioration of material surface because of their influences on mechanical properties of materials. In general, magnetic particle testing, liquid penetrant testing and eddy current testing are commonly used for detecting surface flaws. These methods, however, are neither effective for estimating flaw height nor for evaluating material deterioration. In this paper the authors apply surface wave propagating along the test surface for these purposes. The surface wave (Rayleigh wave) propagates only near the surface layer in the order of one wave length. In other words, the lower the frequency, the deeper the penetration depth of the surface wave. Accordingly, they can select the frequency considering the inspection purpose. On the other hand, when surface wave having broad-band frequency propagates along the surface of a specimen, higher frequency ultrasound propagates very close to the surface and lower frequency ultrasound propagates deeper in the specimen. Hence, frequency analysis is expected to be effective for estimating upper edge of flaw. Surface wave is also very sensitive to material surface properties such as existence of voids or micro cracks. Acoustic characteristics such as sound velocity, attenuation and other feature parameters are influenced by the variation of the material properties. Hence, material deterioration can be evaluated by the acoustic features

  11. Fatigue characteristics of high strength fire resistance steel for frame structure and time-frequency analysis its acoustic emission signal

    International Nuclear Information System (INIS)

    Kim, Hyun Soo; Nam, Ki Woo; Kang, Chang Young

    2000-01-01

    Demand for now nondestructive evaluation are growing to detect fatigue crack growth behavior to predict long term performance of materials and structure in aggressive environments, especially when they are in non-visible area. Acoustic emission technique is well suited to these problems and has drawn a keen interests because of its dynamic detection ability, extreme sensitivity and location of growing defects. In this study, we analysed acoustic emission signals obtained in fatigue and tensile test of high strength fire resistance steel for frame structure with time-frequency analysis methods. The main frequency range is different in the noise and the fatigue crack propagation. It could be classified that it were also generated by composite fracture mechanics of cleavage, dimple, inclusion separation etc

  12. Validation of simulations of an underwater acoustic communication channel characterized by wind-generated surface waves and bubbles

    NARCIS (Netherlands)

    Dol, H.S.; Colin, M.E.G.D.; Ainlie, M.A.; Gerdes, F.; Schäfke, A.; Özkan Sertlekc, H.

    2013-01-01

    This paper shows that it is possible to simulate realistic shallow-water acoustic communication channels using available acoustic propagation models. Key factor is the incorporation of realistic time-dependent sea surface conditions, including both waves and bubbles due to wind.

  13. Integration of BST varactors with surface acoustic wave device by film transfer technology for tunable RF filters

    International Nuclear Information System (INIS)

    Hirano, Hideki; Tanaka, Shuji; Kimura, Tetsuya; Koutsaroff, Ivoyl P; Kadota, Michio; Hashimoto, Ken-ya; Esashi, Masayoshi

    2013-01-01

    This paper presents a film transfer process to integrate barium strontium titanate (BST) metal–insulator–metal (MIM) structures with surface acoustic wave (SAW) devices on a lithium niobate (LN) substrate. A high-quality BST film grown on a Si substrate above 650 °C was patterned into the MIM structures, and transferred to a LN substrate below 130 °C by Ar-plasma-activated Au–Au bonding and the Si lost wafer process. Simple test SAW devices with the transferred BST variable capacitors (VCs) were fabricated and characterized. The resonance frequency of a one-port SAW resonator with the VC connected in series changed from 999 to 1018 MHz, when a dc bias voltage of 3 V was applied to the VC. Although the observed frequency tuning range was smaller than expected due to the degradation of BST in the process, the experimental result demonstrated that a tunable SAW filter with the transferred BST VCs was feasible. (paper)

  14. Stable And Oscillating Acoustic Levitation

    Science.gov (United States)

    Barmatz, Martin B.; Garrett, Steven L.

    1988-01-01

    Sample stability or instability determined by levitating frequency. Degree of oscillation of acoustically levitated object along axis of levitation chamber controlled by varying frequency of acoustic driver for axis above or below frequency of corresponding chamber resonance. Stabilization/oscillation technique applied in normal Earth gravity, or in absence of gravity to bring object quickly to rest at nominal levitation position or make object oscillate in desired range about that position.

  15. Coherent coupling between radio frequency, optical, and acoustic waves in piezo-optomechanical circuits

    Science.gov (United States)

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

    2016-01-01

    Optomechanical cavities have been studied for applications ranging from sensing to quantum information science. Here, we develop a platform for nanoscale cavity optomechanical circuits in which optomechanical cavities supporting co-localized 1550 nm photons and 2.4 GHz phonons are combined with photonic and phononic waveguides. Working in GaAs facilitates manipulation of the localized mechanical mode either with a radio frequency (RF) field through the piezo-electric effect, which produces acoustic waves that are routed and coupled to the optomechanical cavity by phononic crystal waveguides, or optically through the strong photoelastic effect. Along with mechanical state preparation and sensitive readout, we use this to demonstrate an acoustic wave interference effect, similar to atomic coherent population trapping, in which RF-driven coherent mechanical motion is cancelled by optically-driven motion. Manipulating cavity optomechanical systems with equal facility through both photonic and phononic channels enables new architectures for signal transduction between the optical, electrical, and mechanical domains. PMID:27446234

  16. Development and experimental verification of a finite element method for accurate analysis of a surface acoustic wave device

    Science.gov (United States)

    Mohibul Kabir, K. M.; Matthews, Glenn I.; Sabri, Ylias M.; Russo, Salvy P.; Ippolito, Samuel J.; Bhargava, Suresh K.

    2016-03-01

    Accurate analysis of surface acoustic wave (SAW) devices is highly important due to their use in ever-growing applications in electronics, telecommunication and chemical sensing. In this study, a novel approach for analyzing the SAW devices was developed based on a series of two-dimensional finite element method (FEM) simulations, which has been experimentally verified. It was found that the frequency response of the two SAW device structures, each having slightly different bandwidth and center lobe characteristics, can be successfully obtained utilizing the current density of the electrodes via FEM simulations. The two SAW structures were based on XY Lithium Niobate (LiNbO3) substrates and had two and four electrode finger pairs in both of their interdigital transducers, respectively. Later, SAW devices were fabricated in accordance with the simulated models and their measured frequency responses were found to correlate well with the obtained simulations results. The results indicated that better match between calculated and measured frequency response can be obtained when one of the input electrode finger pairs was set at zero volts and all the current density components were taken into account when calculating the frequency response of the simulated SAW device structures.

  17. Surface Acoustic Analog of Bloch Oscillations, Wannier-Stark Ladders and Landau-Zener Tunneling

    Science.gov (United States)

    de Lima, M. M.; Kosevich, Yu. A.; Santos, P. V.; Cantarero, A.

    2011-12-01

    In this contribution, we discuss the recent experimental demonstration of Wannier-Stark ladders, Bloch Oscillations and Landau Zener tunneling in a solid by means of surface acoustic waves propagating through perturbed grating structures.

  18. Use of acoustic vortices in acoustic levitation

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without...

  19. Tuned Chamber Core Panel Acoustic Test Results

    Science.gov (United States)

    Schiller, Noah H.; Allen, Albert R.

    2016-01-01

    This report documents acoustic testing of tuned chamber core panels, which can be used to supplement the low-frequency performance of conventional acoustic treatment. The tuned chamber core concept incorporates low-frequency noise control directly within the primary structure and is applicable to sandwich constructions with a directional core, including corrugated-, truss-, and fluted-core designs. These types of sandwich structures have long, hollow channels (or chambers) in the core. By adding small holes through one of the facesheets, the hollow chambers can be utilized as an array of low-frequency acoustic resonators. These resonators can then be used to attenuate low-frequency noise (below 400 Hz) inside a vehicle compartment without increasing the weight or size of the structure. The results of this test program demonstrate that the tuned chamber core concept is effective when used in isolation or combined with acoustic foam treatments. Specifically, an array of acoustic resonators integrated within the core of the panels was shown to improve both the low-frequency absorption and transmission loss of the structure in targeted one-third octave bands.

  20. Monitoring microbe-induced physical property changes using high-frequency acoustic waveform data: Toward the development of a microbial megascope

    International Nuclear Information System (INIS)

    Williams, Kenneth Hurst

    2002-01-01

    A laboratory investigation was undertaken to determine the effect of microbe generated gas bubbles in controlled, saturated sediment columns utilizing a novel technique involving acoustic wave propagation. Specifically, the effect of denitrifying bacteria on saturated flow conditions was evaluated in light of the stimulated production of N(sub 2) gas and the resulting plugging of the pore throats. The propagation of high frequency acoustic waves through the sediment columns was used to locate those regions in the column where gas accumulation occurred. Over a period of six weeks, regions of gas accumulation resulted in the attenuation of acoustic wave energies with the decreases in amplitude typically greater than one order of magnitude

  1. Monitoring microbe-induced physical property changes using high-frequency acoustic waveform data: Toward the development of a microbial megascope

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Kenneth Hurst [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    A laboratory investigation was undertaken to determine the effect of microbe generated gas bubbles in controlled, saturated sediment columns utilizing a novel technique involving acoustic wave propagation. Specifically, the effect of denitrifying bacteria on saturated flow conditions was evaluated in light of the stimulated production of N2 gas and the resulting plugging of the pore throats. The propagation of high frequency acoustic waves through the sediment columns was used to locate those regions in the column where gas accumulation occurred. Over a period of six weeks, regions of gas accumulation resulted in the attenuation of acoustic wave energies with the decreases in amplitude typically greater than one order of magnitude.

  2. Sound reduction by metamaterial-based acoustic enclosure

    Directory of Open Access Journals (Sweden)

    Shanshan Yao

    2014-12-01

    Full Text Available In many practical systems, acoustic radiation control on noise sources contained within a finite volume by an acoustic enclosure is of great importance, but difficult to be accomplished at low frequencies due to the enhanced acoustic-structure interaction. In this work, we propose to use acoustic metamaterials as the enclosure to efficiently reduce sound radiation at their negative-mass frequencies. Based on a circularly-shaped metamaterial model, sound radiation properties by either central or eccentric sources are analyzed by numerical simulations for structured metamaterials. The parametric analyses demonstrate that the barrier thickness, the cavity size, the source type, and the eccentricity of the source have a profound effect on the sound reduction. It is found that increasing the thickness of the metamaterial barrier is an efficient approach to achieve large sound reduction over the negative-mass frequencies. These results are helpful in designing highly efficient acoustic enclosures for blockage of sound in low frequencies.

  3. Sound reduction by metamaterial-based acoustic enclosure

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Shanshan; Li, Pei; Zhou, Xiaoming; Hu, Gengkai, E-mail: hugeng@bit.edu.cn [Key Laboratory of Dynamics and Control of Flight Vehicle, Ministry of Education and School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2014-12-15

    In many practical systems, acoustic radiation control on noise sources contained within a finite volume by an acoustic enclosure is of great importance, but difficult to be accomplished at low frequencies due to the enhanced acoustic-structure interaction. In this work, we propose to use acoustic metamaterials as the enclosure to efficiently reduce sound radiation at their negative-mass frequencies. Based on a circularly-shaped metamaterial model, sound radiation properties by either central or eccentric sources are analyzed by numerical simulations for structured metamaterials. The parametric analyses demonstrate that the barrier thickness, the cavity size, the source type, and the eccentricity of the source have a profound effect on the sound reduction. It is found that increasing the thickness of the metamaterial barrier is an efficient approach to achieve large sound reduction over the negative-mass frequencies. These results are helpful in designing highly efficient acoustic enclosures for blockage of sound in low frequencies.

  4. Frequency and magnetic field mapping of magnetoelastic spin pumping in high overtone bulk acoustic wave resonator

    Directory of Open Access Journals (Sweden)

    N. I. Polzikova

    2018-05-01

    Full Text Available We report on the first observation of microvolt-scale inverse spin Hall effect (ISHE dc voltage driven by an acoustic spin pumping (ASP in a bulk acoustic wave (BAW resonator formed by a Al-ZnO-Al-YIG(1-GGG-YIG(2-Pt structure. When 2 mW power is applied to an Al-ZnO-Al transducer, the voltage VISHE ∼ 4 μV in the Pt film is observed as a result of resonant ASP from YIG(2 to Pt in the area ∼ 170 μm. The results of frequency and magnetic field mapping of VISHE(f,H together with reflectivity of the resonator show an obvious agreement between the positions of the voltage maxima and BAW resonance frequencies fn(H on the (f, H plane. At the same time a significant asymmetry of the VISHE(fn(H value in reference to the magnetoelastic resonance (MER line fMER(H position is revealed, which is explained by asymmetry of the magnetoelastic waves dispersion law.

  5. Quality factor due to roughness scattering of shear horizontal surface acoustic waves in nanoresonators

    NARCIS (Netherlands)

    Palasantzas, G.

    2008-01-01

    In this work we study the quality factor associated with dissipation due to scattering of shear horizontal surface acoustic waves by random self-affine roughness. It is shown that the quality factor is strongly influenced by both the surface roughness exponent H and the roughness amplitude w to

  6. Acoustic Characterization of Mesoscale Objects

    Energy Technology Data Exchange (ETDEWEB)

    Chinn, D; Huber, R; Chambers, D; Cole, G; Balogun, O; Spicer, J; Murray, T

    2007-03-13

    This report describes the science and engineering performed to provide state-of-the-art acoustic capabilities for nondestructively characterizing mesoscale (millimeter-sized) objects--allowing micrometer resolution over the objects entire volume. Materials and structures used in mesoscale objects necessitate the use of (1) GHz acoustic frequencies and (2) non-contacting laser generation and detection of acoustic waves. This effort demonstrated that acoustic methods at gigahertz frequencies have the necessary penetration depth and spatial resolution to effectively detect density discontinuities, gaps, and delaminations. A prototype laser-based ultrasonic system was designed and built. The system uses a micro-chip laser for excitation of broadband ultrasonic waves with frequency components reaching 1.0 GHz, and a path-stabilized Michelson interferometer for detection. The proof-of-concept for mesoscale characterization is demonstrated by imaging a micro-fabricated etched pattern in a 70 {micro}m thick silicon wafer.

  7. Different quantization mechanisms in single-electron pumps driven by surface acoustic waves

    DEFF Research Database (Denmark)

    Utko, P.; Gloos, K.; Hansen, Jørn Bindslev

    2006-01-01

    We have studied the acoustoelectric current in single-electron pumps driven by surface acoustic waves. We have found that in certain parameter ranges two different sets of quantized steps dominate the acoustoelectric current versus gate-voltage characteristics. In some cases, both types of quanti...

  8. Acoustic propagation within a surface duct in the western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Navelkar, G.S.; Murty, T.V.R.; Murty, C.S.

    Sound speed structure forms a surface duct in the upper 50 m layer in the western Bay of Bengal during late July. A range-dependent acoustic ray computation shows that some rays emanating from a source within the upper 30 m, get trapped within...

  9. On Computations of Duct Acoustics with Near Cut-Off Frequency

    Science.gov (United States)

    Dong, Thomas Z.; Povinelli, Louis A.

    1997-01-01

    The cut-off is a unique feature associated with duct acoustics due to the presence of duct walls. A study of this cut-off effect on the computations of duct acoustics is performed in the present work. The results show that the computation of duct acoustic modes near cut-off requires higher numerical resolutions than others to avoid being numerically cut off. Duct acoustic problems in Category 2 are solved by the DRP finite difference scheme with the selective artificial damping method and results are presented and compared to reference solutions.

  10. Negative refraction imaging of solid acoustic waves by two-dimensional three-component phononic crystal

    International Nuclear Information System (INIS)

    Li Jing; Liu Zhengyou; Qiu Chunyin

    2008-01-01

    By using of the multiple scattering methods, we study the negative refraction imaging effect of solid acoustic waves by two-dimensional three-component phononic crystals composed of coated solid inclusions placed in solid matrix. We show that localized resonance mechanism brings on a group of flat single-mode bands in low-frequency region, which provides two equivalent frequency surfaces (EFS) close to circular. The two constant frequency surfaces correspond to two Bloch modes, a right-handed and a left-handed, whose leading mode are respectively transverse (T) and longitudinal (L) modes. The negative refraction behaviors of the two kinds of modes have been demonstrated by simulation of a Gaussian beam through a finite system. High-quality far-field imaging by a planar lens for transverse or longitudinal waves has been realized separately. This three-component phononic crystal may thus serve as a mode selector in negative refraction imaging of solid acoustic waves

  11. Investigation into the bistatic evolution of the acoustic scattering from a cylindrical shell using time-frequency analysis

    Science.gov (United States)

    Agounad, Said; Aassif, El Houcein; Khandouch, Younes; Maze, Gérard; Décultot, Dominique

    2018-01-01

    The time and frequency analyses of the acoustic scattering by an elastic cylindrical shell in bistatic method show that the arrival times of the echoes and the resonance frequencies of the elastic waves propagating in and around the cylindrical shell are a function of the bistatic angle, β, between the emitter and receiver transducers. The aim of this work is to explain the observed results in time and frequency domains using time-frequency analysis and graphical interpretations. The performance of four widely used time-frequency representations, the Smoothed Pseudo Wigner-Ville (SPWV), the Spectrogram (SP), the reassignment SPWV, and the reassignment SP, are studied. The investigation into the evolution of the time-frequency plane as a function of the bistatic angle β shows that there are the waves propagating in counter-clockwise direction (labeled wave+) and the waves which propagate in clockwise direction (labeled waves-). In this paper the A, S0, and A1 circumferential waves are investigated. The graphical interpretations are used to explain the formation mechanism of these waves and the acoustic scattering in monostatic and bistatic configurations. The delay between the echoes of the waves+ and those of the waves- is expressed in the case of the circumnavigating wave (Scholte-Stoneley wave). This study shows that the observed waves at β = 0 ° and β = 18 0 ° are the result of the constructive interferences between the waves+ and the waves-. A comparative study of the physical properties (group velocity dispersion and cut-off frequency) of the waves+, the waves- and the waves observed in monostatic configuration is conducted. Furthermore, it is shown that the ability of the time-frequency representation to highlight the waves+ and the waves- is very useful, for example, for the detection and the localization of defaults, the classification purposes, etc.

  12. NEAR- AND FAR-FIELD RESPONSE TO COMPACT ACOUSTIC SOURCES IN STRATIFIED CONVECTION ZONES

    Energy Technology Data Exchange (ETDEWEB)

    Cally, Paul S., E-mail: paul.cally@monash.edu [Monash Centre for Astrophysics and School of Mathematical Sciences, Monash University, Clayton, Victoria 3800 (Australia)

    2013-05-01

    The role of the acoustic continuum associated with compact sources in the Sun's interior wave field is explored for a simple polytropic model. The continuum produces a near-field acoustic structure-the so-called acoustic jacket-that cannot be represented by a superposition of discrete normal modes. Particular attention is paid to monochromatic point sources of various frequency and depth, and to the surface velocity power that results, both in the discrete f- and p-mode spectrum and in the continuum. It is shown that a major effect of the continuum is to heal the surface wave field produced by compact sources, and therefore to hide them from view. It is found that the continuous spectrum is not a significant contributor to observable inter-ridge seismic power.

  13. Systematic design of acoustic devices by topology optimization

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Sigmund, Ole

    2005-01-01

    We present a method to design acoustic devices with topology optimization. The general algorithm is exemplified by the design of a reflection chamber that minimizes the transmission of acoustic waves in a specified frequency range.......We present a method to design acoustic devices with topology optimization. The general algorithm is exemplified by the design of a reflection chamber that minimizes the transmission of acoustic waves in a specified frequency range....

  14. Development of a New Surface Acoustic Wave Based Gyroscope on a X-112°Y LiTaO3 Substrate

    Directory of Open Access Journals (Sweden)

    Shitang He

    2011-11-01

    Full Text Available A new micro gyroscope based on the surface acoustic wave (SAW gyroscopic effect was developed. The SAW gyroscopic effect is investigated by applying the surface effective permittivity method in the regime of small ratios of the rotation velocity and the frequency of the SAW. The theoretical analysis indicates that the larger velocity shift was observed from the rotated X-112°Y LiTaO3 substrate. Then, two SAW delay lines with reverse direction and an operation frequency of 160 MHz are fabricated on a same X-112°Y LiTaO3 chip as the feedback of two SAW oscillators, which act as the sensor element. The single-phase unidirectional transducer (SPUDT and combed transducers were used to structure the delay lines to improve the frequency stability of the oscillator. The rotation of a piezoelectric medium gives rise to a shift of the propagation velocity of SAW due to the Coriolis force, resulting in the frequency shift of the SAW device, and hence, the evaluation of the sensor performance. Meanwhile, the differential structure was performed to double the sensitivity and compensate for the temperature effects. Using a precise rate table, the performance of the fabricated SAW gyroscope was evaluated experimentally. A sensitivity of 1.332 Hz deg−1 s at angular rates of up to 1,000 deg s−1 and good linearity are observed.

  15. Carbon nanotubes/ceria composite layers deposited on surface acoustic wave devices for gas detection at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    David, M., E-mail: marjorie.david@univ-tln.fr [Universite du Sud Toulon, Var, IM2NP, UMR CNRS 6242, BP 20132. F 83 957 LA GARDE (France); Arab, M.; Martino, C. [Universite du Sud Toulon, Var, IM2NP, UMR CNRS 6242, BP 20132. F 83 957 LA GARDE (France); Delmas, L. [SENSeOR, Sophia Antipolis, 06250 Mougins (France); Guinneton, F.; Gavarri, J.-R. [Universite du Sud Toulon, Var, IM2NP, UMR CNRS 6242, BP 20132. F 83 957 LA GARDE (France)

    2012-05-01

    Surface acoustic wave (SAW) sensor on ATquartz piezoelectric substrate has been designed and fabricated. Test devices were based on asynchronous single-port resonators operating near the 434-MHz-centered industrial, scientific, and medical band. Multi-Walled Carbon Nanotubes/Ceria (MWNTs/CeO{sub 2}) nanocomposites were used as sensitive layers. The MWNTs were synthesized by catalytic chemical vapor deposition method and coated with nanosized ceria oxide. The composites were deposited on SAW quartz resonator using air-brush technique. MWNTs/CeO{sub 2} nanocomposites were characterized using X-ray diffraction, transmission electron and atomic force microscopy. The sensor responses were tested under acetone (C{sub 3}H{sub 5}OH) and ethanol (C{sub 2}H{sub 5}OH) gases. The output signal was done by S{sub 11} parameter of the SAW device and was monitored using a network analyzer. Frequency changes were observed under acetone and ethanol vapors. These changes depended on the surface conductivity of the nanocomposites deposited on the sensor. The single-port SAW gas sensor coated with the MWNTs/CeO{sub 2} presented the highest sensitivity in the case of acetone vapor interacting with these layers, with a frequency shift of 200 kHz at room temperature.

  16. Investigation of power and frequency for 3D conformal MRI-controlled transurethral ultrasound therapy with a dual frequency multi-element transducer.

    Science.gov (United States)

    N'djin, William Apoutou; Burtnyk, Mathieu; Bronskill, Michael; Chopra, Rajiv

    2012-01-01

    Transurethral ultrasound therapy uses real-time magnetic resonance (MR) temperature feedback to enable the 3D control of thermal therapy accurately in a region within the prostate. Previous canine studies showed the feasibility of this method in vivo. The aim of this study was to reduce the procedure time, while maintaining targeting accuracy, by investigating new combinations of treatment parameters. Simulations and validation experiments in gel phantoms were used, with a collection of nine 3D realistic target prostate boundaries obtained from previous preclinical studies, where multi-slice MR images were acquired with the transurethral device in place. Acoustic power and rotation rate were varied based on temperature feedback at the prostate boundary. Maximum acoustic power and rotation rate were optimised interdependently, as a function of prostate radius and transducer operating frequency. The concept of dual frequency transducers was studied, using the fundamental frequency or the third harmonic component depending on the prostate radius. Numerical modelling enabled assessment of the effects of several acoustic parameters on treatment outcomes. The range of treatable prostate radii extended with increasing power, and tended to narrow with decreasing frequency. Reducing the frequency from 8 MHz to 4 MHz or increasing the surface acoustic power from 10 to 20 W/cm(2) led to treatment times shorter by up to 50% under appropriate conditions. A dual frequency configuration of 4/12 MHz with 20 W/cm(2) ultrasound intensity exposure can treat entire prostates up to 40 cm(3) in volume within 30 min. The interdependence between power and frequency may, however, require integrating multi-parametric functions in the controller for future optimisations.

  17. Magnetoactive Acoustic Metamaterials.

    Science.gov (United States)

    Yu, Kunhao; Fang, Nicholas X; Huang, Guoliang; Wang, Qiming

    2018-04-11

    Acoustic metamaterials with negative constitutive parameters (modulus and/or mass density) have shown great potential in diverse applications ranging from sonic cloaking, abnormal refraction and superlensing, to noise canceling. In conventional acoustic metamaterials, the negative constitutive parameters are engineered via tailored structures with fixed geometries; therefore, the relationships between constitutive parameters and acoustic frequencies are typically fixed to form a 2D phase space once the structures are fabricated. Here, by means of a model system of magnetoactive lattice structures, stimuli-responsive acoustic metamaterials are demonstrated to be able to extend the 2D phase space to 3D through rapidly and repeatedly switching signs of constitutive parameters with remote magnetic fields. It is shown for the first time that effective modulus can be reversibly switched between positive and negative within controlled frequency regimes through lattice buckling modulated by theoretically predicted magnetic fields. The magnetically triggered negative-modulus and cavity-induced negative density are integrated to achieve flexible switching between single-negative and double-negative. This strategy opens promising avenues for remote, rapid, and reversible modulation of acoustic transportation, refraction, imaging, and focusing in subwavelength regimes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Acoustic reflection log in transversely isotropic formations

    Science.gov (United States)

    Ronquillo Jarillo, G.; Markova, I.; Markov, M.

    2018-01-01

    We have calculated the waveforms of sonic reflection logging for a fluid-filled borehole located in a transversely isotropic rock. Calculations have been performed for an acoustic impulse source with the characteristic frequency of tens of kilohertz that is considerably less than the frequencies of acoustic borehole imaging tools. It is assumed that the borehole axis coincides with the axis of symmetry of the transversely isotropic rock. It was shown that the reflected wave was excited most efficiently at resonant frequencies. These frequencies are close to the frequencies of oscillations of a fluid column located in an absolutely rigid hollow cylinder. We have shown that the acoustic reverberation is controlled by the acoustic impedance of the rock Z = Vphρs for fixed parameters of the borehole fluid, where Vph is the velocity of horizontally propagating P-wave; ρs is the rock density. The methods of waveform processing to determine the parameters characterizing the reflected wave have been discussed.

  19. Response Pattern Based on the Amplitude of Ear Canal Recorded Cochlear Microphonic Waveforms across Acoustic Frequencies in Normal Hearing Subjects

    OpenAIRE

    Zhang, Ming

    2012-01-01

    Low-frequency otoacoustic emissions (OAEs) are often concealed by acoustic background noise such as those from a patient’s breathing and from the environment during recording in clinics. When using electrocochleaography (ECochG or ECoG), such as cochlear microphonics (CMs), acoustic background noise do not contaminate the recordings. Our objective is to study the response pattern of CM waveforms (CMWs) to explore an alternative approach in assessing cochlear functions. In response to a 14-mse...

  20. Controlled Acoustic Bass System (CABS) A Method to Achieve Uniform Sound Field Distribution at Low Frequencies in Rectangular Rooms

    DEFF Research Database (Denmark)

    Celestinos, Adrian; Nielsen, Sofus Birkedal

    2008-01-01

    The sound field produced by loudspeakers at low frequencies in small- and medium-size rectangular listening rooms is highly nonuniform due to the multiple reflections and diffractions of sound on the walls and different objects in the room. A new method, called controlled acoustic bass system (CA......-frequency range. CABS has been simulated and measured in two different standard listening rooms with satisfactory results....

  1. On the slow dynamics of near-field acoustically levitated objects under High excitation frequencies

    Science.gov (United States)

    Ilssar, Dotan; Bucher, Izhak

    2015-10-01

    This paper introduces a simplified analytical model describing the governing dynamics of near-field acoustically levitated objects. The simplification converts the equation of motion coupled with the partial differential equation of a compressible fluid, into a compact, second order ordinary differential equation, where the local stiffness and damping are transparent. The simplified model allows one to more easily analyse and design near-field acoustic levitation based systems, and it also helps to devise closed-loop controller algorithms for such systems. Near-field acoustic levitation employs fast ultrasonic vibrations of a driving surface and exploits the viscosity and the compressibility of a gaseous medium to achieve average, load carrying pressure. It is demonstrated that the slow dynamics dominates the transient behaviour, while the time-scale associated with the fast, ultrasonic excitation has a small presence in the oscillations of the levitated object. Indeed, the present paper formulates the slow dynamics under an ultrasonic excitation without the need to explicitly consider the latter. The simplified model is compared with a numerical scheme based on Reynolds equation and with experiments, both showing reasonably good results.

  2. Surface Acoustic Wave (SAW-Enhanced Chemical Functionalization of Gold Films

    Directory of Open Access Journals (Sweden)

    Gina Greco

    2017-10-01

    Full Text Available Surface chemical and biochemical functionalization is a fundamental process that is widely applied in many fields to add new functions, features, or capabilities to a material’s surface. Here, we demonstrate that surface acoustic waves (SAWs can enhance the chemical functionalization of gold films. This is shown by using an integrated biochip composed by a microfluidic channel coupled to a surface plasmon resonance (SPR readout system and by monitoring the adhesion of biotin-thiol on the gold SPR areas in different conditions. In the case of SAW-induced streaming, the functionalization efficiency is improved ≈ 5 times with respect to the case without SAWs. The technology here proposed can be easily applied to a wide variety of biological systems (e.g., proteins, nucleic acids and devices (e.g., sensors, devices for cell cultures.

  3. Polyvinylpyrrolidone/Multiwall Carbon Nanotube Composite Based 36 deg. YX LiTaO3 Surface Acoustic Wave For Hydrogen Gas Sensing Applications

    International Nuclear Information System (INIS)

    Chee, Pei Song; Arsat, Rashidah; He Xiuli; Arsat, Mahyuddin; Wlodarski, Wojtek; Kalantar-zadeh, Kourosh

    2011-01-01

    Poly-vinyl-pyrrolidone (PVP)/Multiwall Carbon Nanotubes (MWNTs) based Surface Acoustic Wave (SAW) sensors are fabricated and characterized, and their performances towards hydrogen gas are investigated. The PVP/MWNTs fibers composite are prepared by electrospinning of the composite aqueous solution deposited directly onto the active area of SAW transducers. Via scanning electron microscopy (SEM), the morphology of the deposited nanostructure material is observed. From the dynamic response, frequency shifts of 530 Hz (1%H 2 ) and 11.322 kHz (0.25%H 2 ) are recorded for the sensors contain of 1.525 g and 1.025 g PVP concentrations, respectively.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  5. Recent advances in the use of acoustics across the frequency spectrum in the oil and gas industry

    Science.gov (United States)

    Zeroug, Smaine; Bose, Sandip

    2018-04-01

    Acoustics enjoys a wide array of applicability in the Oil and Gas industry. Signals with very low-frequencies (tens of Hertz) are routinely used on surface to image the earth subsurface delineating hydrocarbon reservoirs while signals with mid-frequencies (thousands of Hertz) to high-frequencies (hundreds of kilo Hertz) are used in deep boreholes to probe rock mechanical properties and evaluate completion hardware. This article reviews a few recent advances in these applications spanning both measurement concepts and processing and inversion approaches. Three applications are covered, going from high to low frequencies. The first relates to an ultrasonic imager deployed in open boreholes to probe the laminated structure of unconventional shale rock formations at depth of more than 3000 m. The imager yields rock compressional and shear wavespeed images as a function of depth and azimuth revealing a host of geomechanical manifestations of the borehole shape and near-wellbore region at an unprecedented centimetric spatial resolution. The quantitative images have bearing on rock strength and local stresses as they relate to the hydraulic fracturing of these shale formations. The second relates to the interpretation of the complex sonic response in a well cased with double steel strings cemented to the rock formation for the purpose of evaluating the integrity of the cement placed between the outer string and formation. Here, machine learning-based approaches are employed with training on modeling and experimental datasets to develop effective and wellsite diagnosis for the condition of the cement sheath. The third relates to the seismic imaging domain and the deployment of novel accelerometers added to hydrophones on marine seismic cables to capture the subsurface-reflected pressure signals and their spatial gradients. The combination of the two sensors provides the means to deghost the signal from the sea surface reflection, and more importantly, reconstruct the

  6. Laboratory investigation of the acoustic response of seagrass tissue in the frequency band 0.5-2.5 kHz.

    Science.gov (United States)

    Wilson, Preston S; Dunton, Kenneth H

    2009-04-01

    Previous in situ investigations of seagrass have revealed acoustic phenomena that depend on plant density, tissue gas content, and free bubbles produced by photosynthetic activity, but corresponding predictive models that could be used to optimize acoustic remote sensing, shallow water sonar, and mine hunting applications have not appeared. To begin to address this deficiency, low frequency (0.5-2.5 kHz) acoustic laboratory experiments were conducted on three freshly collected Texas Gulf Coast seagrass species. A one-dimensional acoustic resonator technique was used to assess the biomass and effective acoustic properties of the leaves and rhizomes of Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass). Independent biomass and gas content estimates were obtained via microscopic cross-section imagery. The acoustic results were compared to model predictions based on Wood's equation for a two-phase medium. The effective sound speed in the plant-filled resonator was strongly dependent on plant biomass, but the Wood's equation model (based on tissue gas content alone) could not predict the effective sound speed for the low irradiance conditions of the experiment, in which no free bubbles were generated by photosynthesis. The results corroborate previously published results obtained in situ for another seagrass species, Posidonia oceanica.

  7. Discrete microfluidics based on aluminum nitride surface acoustic wave devices

    OpenAIRE

    Zhou, J.; Pang, H.F.; Garcia-Gancedo, L.; Iborra, E.; Clement, M.; De Miguel-Ramos, M.; Jin, H.; Luo, J.K.; Smith, S.; Dong, S.R.; Wang, D.M.; Fu, Y.Q.

    2015-01-01

    To date, most surface acoustic wave (SAW) devices have been made from bulk piezoelectric materials, such as quartz, lithium niobate or lithium tantalite. These bulk materials are brittle, less easily integrated with electronics for control and signal processing, and difficult to realize multiple wave modes or apply complex electrode designs. Using thin film SAWs makes it convenient to integrate microelectronics and multiple sensing or microfluidics techniques into a lab-on-a-chip with low cos...

  8. Computer simulations on the nonlinear frequency shift and nonlinear modulation of ion-acoustic waves

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu; Kamimura, Tetsuo.

    1976-11-01

    The nonlinear behavior of ion-acoustic waves with rather short wave-length, k lambda sub(De) asymptotically equals 1, is investigated by computer sumulations. It is observed that the nonlinear frequency shift is negative and is proportional to square root of the initial wave amplitude when the amplitude is not too large. This proportionality breaks down and the frequency shift can become positive (for large Te/Ti), when (n tilde sub(i)/n 0 )sup(1/2)>0.25, where n tilde sub(i) is the ion density perturbation and n 0 the average plasma density. Nonlinear modulation of the wave-packet is clearly seen; however, modulational instability was not observed. The importance of the effects of trapped ions to these phenomena is emphasized. (auth.)

  9. Interior acoustic cloak

    Directory of Open Access Journals (Sweden)

    Wael Akl

    2014-12-01

    Full Text Available Acoustic cloaks have traditionally been intended to externally surround critical objects to render these objects acoustically invisible. However, in this paper, the emphasis is placed on investigating the application of the acoustic cloaks to the interior walls of acoustic cavities in an attempt to minimize the noise levels inside these cavities. In this manner, the acoustic cloaks can serve as a viable and efficient alternative to the conventional passive noise attenuation treatments which are invariably heavy and bulky. The transformation acoustics relationships that govern the operation of this class of interior acoustic cloaks are presented. Physical insights are given to relate these relationships to the reasons behind the effectiveness of the proposed interior acoustic cloaks. Finite element models are presented to demonstrate the characteristics of interior acoustic cloaks used in treating the interior walls of circular and square cavities both in the time and frequency domains. The obtained results emphasize the effectiveness of the proposed interior cloaks in eliminating the reflections of the acoustic waves from the walls of the treated cavities and thereby rendering these cavities acoustically quiet. It is important to note here that the proposed interior acoustic cloaks can find applications in acoustic cavities such as aircraft cabins and auditoriums as well as many other critical applications.

  10. Analysis of acoustic reflectors for SAW temperature sensor and wireless measurement of temperature

    International Nuclear Information System (INIS)

    Kim, Ki Bok; Kim, Seong Hoon; Jeong, Jae Kee; Shin, Beom Soo

    2013-01-01

    In this study, a wireless and non power SAW (surface acoustic wave) temperature sensor was developed. The single inter digital transducer (IDT) of SAW temperature sensor of which resonance frequency is 434 MHz was fabricated on 128.deg rot-X LiNbO 3 piezoelectric substrate by semiconductor processing technology. To find optimal acoustic reflector for SAW temperature sensor, various kinds of acoustic reflectors were fabricated and their reflection characteristics were analyzed. The IDT type acoustic reflector showed better reflection characteristic than other reflectors. The wireless temperature sensing system consisting of SAW temperature sensor with dipole antenna and a microprocessor based control circuit with dipole antenna for transmitting signal to activate the SAW temperature sensor and receiving the signal from SAW temperature sensor was developed. The result with wireless SAW temperature sensing system showed that the frequency of SAW temperature sensor was linearly decreased with the increase of temperature in the range of 40 to 80.deg.C and the developed wireless SAW temperature sensing system showed the excellent performance with the coefficient of determination of 0.99

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    It has been shown previously that surface acoustic waves can be efficiently trapped and slowed by steep ridges on a piezoelectric substrate, giving rise to two families of shear-horizontal and vertically polarized surface waves. The mechanisms of energy storage and dispersion are explored by using...... the finite element method to model surface acoustic waves generated by high aspect ratio electrodes. A periodic model is proposed including a perfectly matched layer to simulate radiation conditions away from the sources, from which the modal distributions are found. The ratio of the mechanical energy...... confined to the electrode as compared to the total mechanical energy is calculated and is found to be increasing for increasing aspect ratio and to tend to a definite limit for the two families of surface waves. This observation is in support of the interpretation that high aspect ratio electrodes act...

  12. Combined Electric and Acoustic Stimulation With Hearing Preservation: Effect of Cochlear Implant Low-Frequency Cutoff on Speech Understanding and Perceived Listening Difficulty.

    Science.gov (United States)

    Gifford, René H; Davis, Timothy J; Sunderhaus, Linsey W; Menapace, Christine; Buck, Barbara; Crosson, Jillian; O'Neill, Lori; Beiter, Anne; Segel, Phil

    The primary objective of this study was to assess the effect of electric and acoustic overlap for speech understanding in typical listening conditions using semidiffuse noise. This study used a within-subjects, repeated measures design including 11 experienced adult implant recipients (13 ears) with functional residual hearing in the implanted and nonimplanted ear. The aided acoustic bandwidth was fixed and the low-frequency cutoff for the cochlear implant (CI) was varied systematically. Assessments were completed in the R-SPACE sound-simulation system which includes a semidiffuse restaurant noise originating from eight loudspeakers placed circumferentially about the subject's head. AzBio sentences were presented at 67 dBA with signal to noise ratio varying between +10 and 0 dB determined individually to yield approximately 50 to 60% correct for the CI-alone condition with full CI bandwidth. Listening conditions for all subjects included CI alone, bimodal (CI + contralateral hearing aid), and bilateral-aided electric and acoustic stimulation (EAS; CI + bilateral hearing aid). Low-frequency cutoffs both below and above the original "clinical software recommendation" frequency were tested for all patients, in all conditions. Subjects estimated listening difficulty for all conditions using listener ratings based on a visual analog scale. Three primary findings were that (1) there was statistically significant benefit of preserved acoustic hearing in the implanted ear for most overlap conditions, (2) the default clinical software recommendation rarely yielded the highest level of speech recognition (1 of 13 ears), and (3) greater EAS overlap than that provided by the clinical recommendation yielded significant improvements in speech understanding. For standard-electrode CI recipients with preserved hearing, spectral overlap of acoustic and electric stimuli yielded significantly better speech understanding and less listening effort in a laboratory-based, restaurant

  13. Non-destructive evaluation of nuclear material storage container integrity using an acoustic technique

    International Nuclear Information System (INIS)

    Miller, R.F.; Pechersky, M.J.; Raju, P.K.

    1994-01-01

    A non-intrusive method for determining the gas mixture in a sealed container using acoustics has been conceived. Analysis has shown that it is possible to both excite the acoustic resonance of the gas cavity, and detect when resonance occurs from the outside surface of the container. The resonant frequency of the acoustic cavity is dependent on the molecular weight of the gas that fills it. A change in the mixture of gases within the cavity alters the gas molecular weight and can produce a detectable change in the resonant frequency of the cavity. This concept provides a method of monitoring and/or analyzing the gas mixture in a sealed container without taking physical samples. An advantage of this technique is that it eliminates safety and contamination risks associated with breaching a pressure boundary and taking a sample of potentially hazardous gases in order to monitor or analyze the mixture

  14. Ares I Scale Model Acoustic Test Instrumentation for Acoustic and Pressure Measurements

    Science.gov (United States)

    Vargas, Magda B.; Counter, Douglas

    2011-01-01

    Ares I Scale Model Acoustic Test (ASMAT) is a 5% scale model test of the Ares I vehicle, launch pad and support structures conducted at MSFC to verify acoustic and ignition environments and evaluate water suppression systems Test design considerations 5% measurements must be scaled to full scale requiring high frequency measurements Users had different frequencies of interest Acoustics: 200 - 2,000 Hz full scale equals 4,000 - 40,000 Hz model scale Ignition Transient: 0 - 100 Hz full scale equals 0 - 2,000 Hz model scale Environment exposure Weather exposure: heat, humidity, thunderstorms, rain, cold and snow Test environments: Plume impingement heat and pressure, and water deluge impingement Several types of sensors were used to measure the environments Different instrument mounts were used according to the location and exposure to the environment This presentation addresses the observed effects of the selected sensors and mount design on the acoustic and pressure measurements

  15. An acoustic prion assay

    Directory of Open Access Journals (Sweden)

    Gordon Hayward

    2016-12-01

    Full Text Available An acoustic prion assay has been demonstrated for sheep brain samples. Only five false positives and no false negatives were observed in a test of 45 positive and 45 negative samples. The acoustic prion sensor was constructed using a thickness shear mode quartz resonator coated with a covalently bound recombinant prion protein. The characteristic indicator of a scrapie infected sheep brain sample was an observed shoulder in the frequency decrease in response to a sample.The response of the sensor aligns with a conformational shift in the surface protein and with the propagation mechanism of the disease. This alignment is evident in the response timing and shape, dependence on concentration, cross species behaviour and impact of blood plasma. This alignment is far from sufficient to prove the mechanism of the sensor but it does offer the possibility of a rapid and inexpensive additional tool to explore prion disease. Keywords: Prions, Thickness shear mode quartz sensor

  16. Anti-sound and Acoustical Cloaks

    Directory of Open Access Journals (Sweden)

    Veturia CHIROIU

    2016-12-01

    Full Text Available The principles by which the acoustics can be mimicked in order to reduce or cancel the vibrational field are based on anti-sound concept which can be materialized by acoustic cloaks. Geometric transformations open an elegant way towards the unconstrained control of sound through acoustic metamaterials. Acoustic cloaks can be achieved through geometric transformations which bring exotic metamaterial properties into the acoustic equations. Our paper brings new ideas concerning the technological keys for manufacturing of novel metamaterials based on the spatial compression of Cantor structures, and the architecture of 3D acoustic cloaks in a given frequency band, with application to architectural acoustics.

  17. Multichannel analysis of surface-waves and integration of downhole acoustic televiewer imaging, ultrasonic Vs and Vp, and vertical seismic profiling in an NEHRP-standard classification, South of Concordia, Kansas, USA

    Science.gov (United States)

    Raef, Abdelmoneam; Gad, Sabreen; Tucker-Kulesza, Stacey

    2015-10-01

    Seismic site characteristics, as pertaining to earthquake hazard reduction, are a function of the subsurface elastic moduli and the geologic structures. This study explores how multiscale (surface, downhole, and laboratory) datasets can be utilized to improve "constrained" average Vs30 (shear-wave velocity to a 30-meter depth). We integrate borehole, surface and laboratory measurements for a seismic site classification based on the standards of the National Earthquake Hazard Reduction Program (NEHRP). The seismic shear-wave velocity (Vs30) was derived from a geophysical inversion workflow that utilized multichannel analysis of surface-waves (MASW) and downhole acoustic televiewer imaging (DATI). P-wave and S-wave velocities, based on laboratory measurements of arrival times of ultrasonic-frequency signals, supported the workflow by enabling us to calculate Poisson's ratio, which was incorporated in building an initial model for the geophysical inversion of MASW. Extraction of core samples from two boreholes provided lithology and thickness calibration of the amplitudes of the acoustic televiewer imaging for each layer. The MASW inversion, for calculating Vs sections, was constrained with both ultrasonic laboratory measurements (from first arrivals of Vs and Vp waveforms at simulated in situ overburden stress conditions) and the downhole acoustic televiewer (DATV) amplitude logs. The Vs30 calculations enabled categorizing the studied site as NEHRP-class "C" - very dense soil and soft rock. Unlike shallow fractured carbonates in the studied area, S-wave and P-wave velocities at ultrasonic frequency for the deeper intact shale core-samples from two boreholes were in better agreement with the corresponding velocities from both a zero-offset vertical seismic profiling (VSP) and inversion of Rayleigh-wave velocity dispersion curves.

  18. An adjustable multi-scale single beam acoustic tweezers based on ultrahigh frequency ultrasonic transducer.

    Science.gov (United States)

    Chen, Xiaoyang; Lam, Kwok Ho; Chen, Ruimin; Chen, Zeyu; Yu, Ping; Chen, Zhongping; Shung, K Kirk; Zhou, Qifa

    2017-11-01

    This paper reports the fabrication, characterization, and microparticle manipulation capability of an adjustable multi-scale single beam acoustic tweezers (SBAT) that is capable of flexibly changing the size of "tweezers" like ordinary metal tweezers with a single-element ultrahigh frequency (UHF) ultrasonic transducer. The measured resonant frequency of the developed transducer at 526 MHz is the highest frequency of piezoelectric single crystal based ultrasonic transducers ever reported. This focused UHF ultrasonic transducer exhibits a wide bandwidth (95.5% at -10 dB) due to high attenuation of high-frequency ultrasound wave, which allows the SBAT effectively excite with a wide range of excitation frequency from 150 to 400 MHz by using the "piezoelectric actuator" model. Through controlling the excitation frequency, the wavelength of ultrasound emitted from the SBAT can be changed to selectively manipulate a single microparticle of different sizes (3-100 μm) by using only one transducer. This concept of flexibly changing "tweezers" size is firstly introduced into the study of SBAT. At the same time, it was found that this incident ultrasound wavelength play an important role in lateral trapping and manipulation for microparticle of different sizes. Biotechnol. Bioeng. 2017;114: 2637-2647. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

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

    Science.gov (United States)

    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

  20. Transport Powder and Liquid Samples by Surface Acoustic Waves

    Science.gov (United States)

    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.

  1. Noise suppression in curved glass shells using macro-fiber-composite actuators studied by the means of digital holography and acoustic measurements

    Directory of Open Access Journals (Sweden)

    P. Mokrý

    2015-02-01

    Full Text Available The paper presents methods and experimental results of the semi-active control of noise transmission in a curved glass shell with attached piezoelectric macro fiber composite (MFC actuators. The semi-active noise control is achieved via active elasticity control of piezoelectric actuators by connecting them to an active electric shunt circuit that has a negative effective capacitance. Using this approach, it is possible to suppress the vibration of the glass shell in the normal direction with respect to its surface and to increase the acoustic transmission loss of the piezoelectric MFC-glass composite structure. The effect of the MFC actuators connected to the negative capacitance shunt circuit on the surface distribution of the normal vibration amplitude is studied using frequency-shifted digital holography (FSDH. The principle of the used FSDH method is described in the paper. The frequency dependence of the acoustic transmission loss through the piezoelectric MFC-glass composite structure is estimated using measurements of the specific acoustic impedance of the curved glass shell. The specific acoustic impedance is measured using two microphones and a laser Doppler vibrometer (LDV. The results from the LDV measurements are compared with the FSDH data. The results of the experiments show that using this approach, the acoustic transmission loss in a glass shell can be increased by 36 dB in the frequency range around 247 Hz and by 25 dB in the frequency range around 258 Hz. The experiments indicate that FSDH measurements provide an efficient tool that can be used for fast and accurate measurements of the acoustic transmission loss in large planar structures.

  2. A new type of surface acoustic waves in solids due to nonlinear elasticity

    International Nuclear Information System (INIS)

    Mozhaev, V.G.

    1988-12-01

    It is shown that in nonlinear elastic semi-infinite medium possessing a property of self focusing of shear waves, besides bulk non-linear shear waves, new surface acoustic waves exist, localization of which near the boundary is entirely due to nonlinear effects. (author). 8 refs

  3. Acoustic transfer function of cavity and its application to rapid evaluation of sound field at low frequency band

    Institute of Scientific and Technical Information of China (English)

    YIN Gang; CHEN Hualing; HU Xuanli; HUANG Xieqing

    2001-01-01

    A new method to obtain numerical solution of Acoustic Transfer Function (ATF) by BEM is presented. For a simply supported panel backed by a rectangular cavity at low frequency band (0-200 Hz), the frequency property of ATF is analyzed. The relation between the accuracy of the rapid evaluation of sound field and the discretization schemes of the vibrational panel is discussed. The result shows that the method to obtain ATF and the rapid evaluation of sound field using the ATF is suitable to low frequency band. If an appropriate discretization scheme is choosed based on the frequency involved and the effort to obtain ATF, the accuracy of the rapid evaluation of sound field is acceptable.

  4. Estimating sub-surface dispersed oil concentration using acoustic backscatter response.

    Science.gov (United States)

    Fuller, Christopher B; Bonner, James S; Islam, Mohammad S; Page, Cheryl; Ojo, Temitope; Kirkey, William

    2013-05-15

    The recent Deepwater Horizon disaster resulted in a dispersed oil plume at an approximate depth of 1000 m. Several methods were used to characterize this plume with respect to concentration and spatial extent including surface supported sampling and autonomous underwater vehicles with in situ instrument payloads. Additionally, echo sounders were used to track the plume location, demonstrating the potential for remote detection using acoustic backscatter (ABS). This study evaluated use of an Acoustic Doppler Current Profiler (ADCP) to quantitatively detect oil-droplet suspensions from the ABS response in a controlled laboratory setting. Results from this study showed log-linear ABS responses to oil-droplet volume concentration. However, the inability to reproduce ABS response factors suggests the difficultly in developing meaningful calibration factors for quantitative field analysis. Evaluation of theoretical ABS intensity derived from the particle size distribution provided insight regarding method sensitivity in the presence of interfering ambient particles. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Detecting vocal fatigue in student singers using acoustic measures of mean fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio

    Science.gov (United States)

    Sisakun, Siphan

    2000-12-01

    The purpose of this study is to explore the ability of four acoustic parameters, mean fundamental frequency, jitter, shimmer, and harmonics-to-noise ratio, to detect vocal fatigue in student singers. The participants are 15 voice students, who perform two distinct tasks, data collection task and vocal fatiguing task. The data collection task includes the sustained vowel /a/, reading a standard passage, and self-rate on a vocal fatigue form. The vocal fatiguing task is the vocal practice of musical scores for a total of 45 minutes. The four acoustic parameters are extracted using the software EZVoicePlus. The data analyses are performed to answer eight research questions. The first four questions relate to correlations of the self-rating scale and each of the four parameters. The next four research questions relate to differences in the parameters over time using one-factor repeated measures analysis of variance (ANOVA). The result yields a proposed acoustic profile of vocal fatigue in student singers. This profile is characterized by increased fundamental frequency; slightly decreased jitter; slightly decreased shimmer; and slightly increased harmonics-to-noise ratio. The proposed profile requires further investigation.

  6. Characterizing riverbed sediment using high-frequency acoustics 2: scattering signatures of Colorado River bed sediment in Marble and Grand Canyons

    Science.gov (United States)

    Buscombe, Daniel D.; Grams, Paul E.; Kaplinski, Matt A.

    2014-01-01

    In this, the second of a pair of papers on the statistical signatures of riverbed sediment in high-frequency acoustic backscatter, spatially explicit maps of the stochastic geometries (length- and amplitude-scales) of backscatter are related to patches of riverbed surfaces composed of known sediment types, as determined by geo-referenced underwater video observations. Statistics of backscatter magnitudes alone are found to be poor discriminators between sediment types. However, the variance of the power spectrum, and the intercept and slope from a power-law spectral form (termed the spectral strength and exponent, respectively) successfully discriminate between sediment types. A decision-tree approach was able to classify spatially heterogeneous patches of homogeneous sands, gravels (and sand-gravel mixtures), and cobbles/boulders with 95, 88, and 91% accuracy, respectively. Application to sites outside the calibration, and surveys made at calibration sites at different times, were plausible based on observations from underwater video. Analysis of decision trees built with different training data sets suggested that the spectral exponent was consistently the most important variable in the classification. In the absence of theory concerning how spatially variable sediment surfaces scatter high-frequency sound, the primary advantage of this data-driven approach to classify bed sediment over alternatives is that spectral methods have well understood properties and make no assumptions about the distributional form of the fluctuating component of backscatter over small spatial scales.

  7. Chirped or time modulated excitation compared to short pulses for photoacoustic imaging in acoustic attenuating media

    Science.gov (United States)

    Burgholzer, P.; Motz, C.; Lang, O.; Berer, T.; Huemer, M.

    2018-02-01

    In photoacoustic imaging, optically generated acoustic waves transport the information about embedded structures to the sample surface. Usually, short laser pulses are used for the acoustic excitation. Acoustic attenuation increases for higher frequencies, which reduces the bandwidth and limits the spatial resolution. One could think of more efficient waveforms than single short pulses, such as pseudo noise codes, chirped, or harmonic excitation, which could enable a higher information-transfer from the samples interior to its surface by acoustic waves. We used a linear state space model to discretize the wave equation, such as the Stoke's equation, but this method could be used for any other linear wave equation. Linear estimators and a non-linear function inversion were applied to the measured surface data, for onedimensional image reconstruction. The proposed estimation method allows optimizing the temporal modulation of the excitation laser such that the accuracy and spatial resolution of the reconstructed image is maximized. We have restricted ourselves to one-dimensional models, as for higher dimensions the one-dimensional reconstruction, which corresponds to the acoustic wave without attenuation, can be used as input for any ultrasound imaging method, such as back-projection or time-reversal method.

  8. The Acoustical Apparatus of Rudolph Koenig.

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    1992-01-01

    Discusses the history of Rudolph Koenig's contribution to the development of acoustical apparatus. Contributions include the clock fork to determine absolute acoustic frequencies, a forerunner of the oscilloscope called the manometric flame, and an acoustic interference apparatus used in the Fourier synthesis of musical sounds. (MDH)

  9. Stochastic dislocation kinetics and fractal structures in deforming metals probed by acoustic emission and surface topography measurements

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradov, A. [Laboratory for the Physics of Strength of Materials and Intelligent Diagnostic Systems, Togliatti State University, Togliatti 445667 (Russian Federation); Laboratory of Hybrid Nanostructured Materials, NITU MISiS, Moscow 119490 (Russian Federation); Yasnikov, I. S. [Laboratory for the Physics of Strength of Materials and Intelligent Diagnostic Systems, Togliatti State University, Togliatti 445667 (Russian Federation); Estrin, Y. [Laboratory of Hybrid Nanostructured Materials, NITU MISiS, Moscow 119490 (Russian Federation); Centre for Advanced Hybrid Materials, Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia)

    2014-06-21

    We demonstrate that the fractal dimension (FD) of the dislocation population in a deforming material is an important quantitative characteristic of the evolution of the dislocation structure. Thus, we show that peaking of FD signifies a nearing loss of uniformity of plastic flow and the onset of strain localization. Two techniques were employed to determine FD: (i) inspection of surface morphology of the deforming crystal by white light interferometry and (ii) monitoring of acoustic emission (AE) during uniaxial tensile deformation. A connection between the AE characteristics and the fractal dimension determined from surface topography measurements was established. As a common platform for the two methods, the dislocation density evolution in the bulk was used. The relations found made it possible to identify the occurrence of a peak in the median frequency of AE as a harbinger of plastic instability leading to necking. It is suggested that access to the fractal dimension provided by AE measurements and by surface topography analysis makes these techniques important tools for monitoring the evolution of the dislocation structure during plastic deformation—both as stand-alone methods and especially when used in tandem.

  10. A Finite Element Model of a MEMS-based Surface Acoustic Wave Hydrogen Sensor

    Directory of Open Access Journals (Sweden)

    Walied A. Moussa

    2010-02-01

    Full Text Available Hydrogen plays a significant role in various industrial applications, but careful handling and continuous monitoring are crucial since it is explosive when mixed with air. Surface Acoustic Wave (SAW sensors provide desirable characteristics for hydrogen detection due to their small size, low fabrication cost, ease of integration and high sensitivity. In this paper a finite element model of a Surface Acoustic Wave sensor is developed using ANSYS12© and tested for hydrogen detection. The sensor consists of a YZ-lithium niobate substrate with interdigital electrodes (IDT patterned on the surface. A thin palladium (Pd film is added on the surface of the sensor due to its high affinity for hydrogen. With increased hydrogen absorption the palladium hydride structure undergoes a phase change due to the formation of the β-phase, which deteriorates the crystal structure. Therefore with increasing hydrogen concentration the stiffness and the density are significantly reduced. The values of the modulus of elasticity and the density at different hydrogen concentrations in palladium are utilized in the finite element model to determine the corresponding SAW sensor response. Results indicate that with increasing the hydrogen concentration the wave velocity decreases and the attenuation of the wave is reduced.

  11. Acoustic manipulation of active spherical carriers: Generation of negative radiation force

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, Majid, E-mail: majid_rajabi@iust.ac.ir; Mojahed, Alireza

    2016-09-15

    This paper examines theoretically a novel mechanism of generating negative (pulling) radiation force for acoustic manipulation of spherical carriers equipped with piezoelectric actuators in its inner surface. In this mechanism, the spherical particle is handled by common plane progressive monochromatic acoustic waves instead of zero-/higher- order Bessel beams or standing waves field. The handling strategy is based on applying a spatially uniform harmonic electrical voltage at the piezoelectric actuator with the same frequency of handling acoustic waves, in order to change the radiation force effect from repulsive (away from source) to attractive (toward source). This study may be considered as a start point for development of contact-free precise handling and entrapment technology of active carriers which are essential in many engineering and medicine applications.

  12. Acoustic emission-based in-process monitoring of surface generation in robot-assisted polishing

    DEFF Research Database (Denmark)

    Pilny, Lukas; Bissacco, Giuliano; De Chiffre, Leonardo

    2016-01-01

    The applicability of acoustic emission (AE) measurements for in-process monitoring of surface generation in the robot-assisted polishing (RAP) was investigated. Surface roughness measurements require interruption of the process, proper surface cleaning and measurements that sometimes necessitate...... automatic detection of optimal process endpoint allow intelligent process control, creating fundamental elements in development of robust fully automated RAP process for its widespread industrial application....... removal of the part from the machine tool. In this study, stabilisation of surface roughness during polishing rotational symmetric surfaces by the RAP process was monitored by AE measurements. An AE sensor was placed on a polishing arm in direct contact with a bonded abrasive polishing tool...

  13. Wide-range frequency selectivity in an acoustic sensor fabricated using a microbeam array with non-uniform thickness

    International Nuclear Information System (INIS)

    Shintaku, Hirofumi; Kotera, Hidetoshi; Kobayashi, Takayuki; Zusho, Kazuki; Kawano, Satoyuki

    2013-01-01

    In this study, we have demonstrated the fabrication of a microbeam array (MBA) with various thicknesses and investigated the suitability it for an acoustic sensor with wide-range frequency selectivity. For this, an MBA composed of 64 beams, with thicknesses varying from 2.99–142 µm, was fabricated by using single gray-scale lithography and a thick negative photoresist. The vibration of the beams in air was measured using a laser Doppler vibrometer; the resonant frequencies of the beams were measured to be from 11.5 to 290 kHz. Lastly, the frequency range of the MBA with non-uniform thickness was 10.9 times that of the MBA with uniform thickness. (paper)

  14. X-ray diffraction and surface acoustic wave analysis of BST/Pt/TiO{sub 2}/SiO{sub 2}/Si thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mseddi, Souhir; Hedi Ben Ghozlen, Mohamed [Laboratoire de Physique des Materiaux, Faculte des Sciences de Sfax, Universite de Sfax, 3018 Sfax (Tunisia); Njeh, Anouar [Unite de Physique, Informatique et Matematiques, Faculte des Sciences de Gafsa, Universite de Gafsa, 2112 Gafsa (Tunisia); Schneider, Dieter [Fraunhofer-Institut fuer Material- und Strahltechnologie, Winterbergstrasse 28, 1277 Dresden (Germany); Fuess, Hartmut [Institute of Materials Science, University of Technology, Petersenstr.23, 64287 Darmstadt (Germany)

    2011-11-15

    High dielectric constant and electrostriction property of (Ba, Sr)Ti0{sub 3} (BST) thin films result in an increasing interest for dielectric devices and microwave acoustic resonator. Barium strontium titanate (Ba{sub 0.645}Sr{sub 0.355}TiO{sub 3}) films of about 300 nm thickness are grown on Pt(111)/TiO{sub 2}/SiO{sub 2}/Si(001) substrates by rf magnetron sputtering deposition techniques. X-ray diffraction is applied for the microstructural characterization. The BST films exhibit a cubic perovskite structure with a dense and smooth surface. A laser acoustic waves (LA-waves) technique is used to generate surface acoustic waves (SAW) propagating in the BST films. Young's modulus E and the Poisson ratio {nu} of TiO{sub 2,} Pt and BST films in different propagation directions are derived from the measured dispersion curves. Estimation of BST elastics constants are served in SAW studies. Impact of stratification process on SAW, propagating along [100] and [110] directions of silicon substrate, has been interpreted on the basis of ordinary differential equation (ODE) and stiffness matrix method (SMM). A good agreement is observed between experimental and calculated dispersion curves. The performed calculations are strongly related to the implemented crystallographic data of each layer. Dispersion curves are found to be sensitive to the SAW propagation direction and the stratification process for the explored frequency ranges 50-250 MHz, even though it corresponds to a wave length clearly higher than the whole films thickness.

  15. Acoustic study of YBa sub 2 Cu sub 3 O sub x thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.; Chi, C.; Koren, G.; Gupta, A. (IBM Research Division, Thomas J. Watson Research Center, P. O. Box 218, Yorktown Heights, New York 10598 (US))

    1991-03-01

    The attenuation of surface acoustic waves by epitaxial YBa{sub 2}Cu{sub 3}O{sub {ital x}} films has been studied for {ital x}{congruent}6 to 7. For fully oxygenated samples, the acoustic attenuation as a function of temperature shows two broad peaks at about 135 and 240 K, and decreases monotonically below the lower peak temperature. The cause of attenuation peaks is attributed to scattering by optical phonons. Our data do not show any gap structure at {ital T}{sub {ital c}} due to relatively weak electron-phonon interactions at the acoustic frequencies. As the oxygen deficiency increases, the temperature dependence of the dc resistance changes from metallic to semiconducting and finally to insulating behavior. Acoustic attenuation data correspondingly show a drastic change due to different attenuation mechanisms: from the phonon scattering loss in the metallic regime to the electric-field coupling loss in the semiconducting and insulating regimes. In the latter regimes, the temperature dependence of low-frequency resistance calculated from the attenuation data can be fitted to a three-dimensional Mott variable-range-hopping model.

  16. Acoustic phenomena observed in lung auscultation

    Science.gov (United States)

    Korenbaum, V. I.; Tagil'Tsev, A. A.; Kulakov, Yu. V.

    2003-05-01

    The results of studying respiratory noise at the chest wall by the method of acoustic intensimetry reveal the presence of frequency components with different signs of the real and imaginary parts of the cross spectrum obtained for the responses of the receivers of vibratory displacement and dynamic force. An acoustic model is proposed to explain this difference on the basis of the hypothesis that the contributions of both air-borne and structure-borne sound are significant in the transmission of respiratory noise to the chest wall. It is shown that, when considered as an acoustic channel for the basic respiratory noise, the respiratory system of an adult subject has two resonances: in the frequency bands within 110 150 and 215 350 Hz. For adults in normal condition, the air-borne component of the basic respiratory noise predominates in the region 100 300 Hz in the lower parts of lungs. At forced respiration of healthy adults, the sounds of vesicular respiration are generated by the turbulent air flow in the 11th-through 13th-generation bronchi, and the transmission of these sounds to the chest wall in normal condition is mainly through air and is determined by the resonance of the vibratory system formed by the elasticity of air in the respiratory ducts of lungs and by the surface mass density of the chest wall. It is demonstrated that the distance from the chest wall to the sources of structure-borne additional respiratory noise, namely, wheezing with frequencies above 300 Hz, can be estimated numerically from the ratio between the real and imaginary parts of the cross spectrum on the assumption that the source is of the quadrupole type.

  17. Forward and inverse problems for surface acoustic waves in anisotropic media: A Ritz-Rayleigh method based approach

    Czech Academy of Sciences Publication Activity Database

    Stoklasová, Pavla; Sedlák, Petr; Seiner, Hanuš; Landa, Michal

    2015-01-01

    Roč. 56, February 2015 (2015), s. 381-389 ISSN 0041-624X R&D Projects: GA ČR GPP101/12/P428 Institutional support: RVO:61388998 Keywords : surface acoustic waves * anisotropic materials * Ritz-Rayleigh method * inverse problem Subject RIV: BI - Acoustics Impact factor: 1.954, year: 2015 http://www.sciencedirect.com/science/article/pii/S0041624X14002686

  18. High quality broadband spatial reflections of slow Rayleigh surface acoustic waves modulated by a graded grooved surface

    KAUST Repository

    Xu, Yanlong

    2015-01-21

    We report high quality broadband spatial reflections of Rayleigh surface acoustic waves (SAWs) through a graded grooved surface. High quality means that no wave is allowed to transmit and the incident wave is nearly all reflected to the input side. The graded grooved surface is structured by drilling one dimensional array of graded grooves with increased depths on a flat surface. We investigate SAW dispersion relations, wave field distribution at several typical SAW wavelengths, and time evolution of a Gaussian pulse through the graded grooved surface. Results show that the input broadband Rayleigh SAWs can be slowed, spatially enhanced and stopped, and finally reflected to the input side. The study suggests that engraving the flat surface can be used as an efficient and economical way to manipulate Rayleigh SAWs, which has potential application in novel SAW devices such as filters, reflectors, sensors, energy harvesters, and diodes.

  19. Characteristics of coupled acoustic wave propagation in metal pipe

    International Nuclear Information System (INIS)

    Kim, Ho Wuk; Kim, Min Soo; Lee, Sang Kwon

    2008-01-01

    The circular cylinder pipes are used in the many industrial areas. In this paper, the acoustic wave propagation in the pipe containing gas is researched. First of all, the theory for the coupled acoustic wave propagation in a pipe is investigated. Acoustic wave propagation in pipe can not be occurred independently between the wave of the fluid and the shell. It requires complicated analysis. However, as a special case, the coupled wave in a high density pipe containing a light density medium is corresponded closely to the uncoupled in-vacuo shell waves and to the rigid-walled duct fluid waves. The coincidence frequencies of acoustic and shell modes contribute to the predominant energy transmission. The coincidence frequency means the frequency corresponding to the coincidence of the wavenumber in both acoustic and shell. In this paper, it is assumed that the internal medium is much lighter than the pipe shell. After the uncoupled acoustic wave in the internal medium and uncoupled shell wave are considered, the coincidence frequencies are found. The analysis is successfully confirmed by the verification of the experiment using the real long steel pipe. This work verifies that the coupled wave characteristic of the shell and the fluid is occurred as predominant energy transmission at the coincidence frequencies

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

    Science.gov (United States)

    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.

  1. Acoustic holograms of active regions

    International Nuclear Information System (INIS)

    Chou, Dean-Yi

    2008-01-01

    We propose a method to study solar magnetic regions in the solar interior with the principle of optical holography. A magnetic region in the solar interior scatters the solar background acoustic waves. The scattered waves and background waves could form an interference pattern on the solar surface. We investigate the feasibility of detecting this interference pattern on the solar surface, and using it to construct the three-dimensional scattered wave from the magnetic region with the principle of optical holography. In solar acoustic holography, the background acoustic waves play the role of reference wave; the magnetic region plays the role of the target object; the interference pattern, acoustic power map, on the solar surface plays the role of the hologram.

  2. Acoustic holograms of active regions

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Dean-Yi [Physics Department, National Tsing Hua University, Hsinchu, 30013, Taiwan (China)], E-mail: chou@phys.nthu.edu.tw

    2008-10-15

    We propose a method to study solar magnetic regions in the solar interior with the principle of optical holography. A magnetic region in the solar interior scatters the solar background acoustic waves. The scattered waves and background waves could form an interference pattern on the solar surface. We investigate the feasibility of detecting this interference pattern on the solar surface, and using it to construct the three-dimensional scattered wave from the magnetic region with the principle of optical holography. In solar acoustic holography, the background acoustic waves play the role of reference wave; the magnetic region plays the role of the target object; the interference pattern, acoustic power map, on the solar surface plays the role of the hologram.

  3. Controlling Sample Rotation in Acoustic Levitation

    Science.gov (United States)

    Barmatz, M. B.; Stoneburner, J. D.

    1985-01-01

    Rotation of acoustically levitated object stopped or controlled according to phase-shift monitoring and control concept. Principle applies to square-cross-section levitation chamber with two perpendicular acoustic drivers operating at same frequency. Phase difference between X and Y acoustic excitation measured at one corner by measuring variation of acoustic amplitude sensed by microphone. Phase of driver adjusted to value that produces no rotation or controlled rotation of levitated object.

  4. Coupling a Surface Acoustic Wave to an Electron Spin in Diamond via a Dark State

    Directory of Open Access Journals (Sweden)

    D. Andrew Golter

    2016-12-01

    Full Text Available The emerging field of quantum acoustics explores interactions between acoustic waves and artificial atoms and their applications in quantum information processing. In this experimental study, we demonstrate the coupling between a surface acoustic wave (SAW and an electron spin in diamond by taking advantage of the strong strain coupling of the excited states of a nitrogen vacancy center while avoiding the short lifetime of these states. The SAW-spin coupling takes place through a Λ-type three-level system where two ground spin states couple to a common excited state through a phonon-assisted as well as a direct dipole optical transition. Both coherent population trapping and optically driven spin transitions have been realized. The coherent population trapping demonstrates the coupling between a SAW and an electron spin coherence through a dark state. The optically driven spin transitions, which resemble the sideband transitions in a trapped-ion system, can enable the quantum control of both spin and mechanical degrees of freedom and potentially a trapped-ion-like solid-state system for applications in quantum computing. These results establish an experimental platform for spin-based quantum acoustics, bridging the gap between spintronics and quantum acoustics.

  5. Observation of self-excited acoustic vortices in defect-mediated dust acoustic wave turbulence.

    Science.gov (United States)

    Tsai, Ya-Yi; I, Lin

    2014-07-01

    Using the self-excited dust acoustic wave as a platform, we demonstrate experimental observation of self-excited fluctuating acoustic vortex pairs with ± 1 topological charges through spontaneous waveform undulation in defect-mediated turbulence for three-dimensional traveling nonlinear longitudinal waves. The acoustic vortex pair has helical waveforms with opposite chirality around the low-density hole filament pair in xyt space (the xy plane is the plane normal to the wave propagation direction). It is generated through ruptures of sequential crest surfaces and reconnections with their trailing ruptured crest surfaces. The initial rupture is originated from the amplitude reduction induced by the formation of the kinked wave crest strip with strong stretching through the undulation instability. Increasing rupture causes the separation of the acoustic vortex pair after generation. A similar reverse process is followed for the acoustic vortex annihilating with the opposite-charged acoustic vortex from the same or another pair generation.

  6. Enhancement of acousto-optical coupling in two-dimensional air-slot phoxonic crystal cavities by utilizing surface acoustic waves

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Tian-Xue [Institute of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044 (China); Wang, Yue-Sheng, E-mail: yswang@bjtu.edu.cn [Institute of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Chuanzeng [Department of Civil Engineering, University of Siegen, D-57068 Siegen (Germany)

    2017-01-30

    A phoxonic crystal is a periodically patterned material that can simultaneously localize optical and acoustic modes. The acousto-optical coupling in two-dimensional air-slot phoxonic crystal cavities is investigated numerically. The photons can be well confined in the slot owing to the large electric field discontinuity at the air/dielectric interfaces. Besides, the surface acoustic modes lead to the localization of the phonons near the air-slot. The high overlap of the photonic and phononic cavity modes near the slot results in a significant enhancement of the moving interface effect, and thus strengthens the total acousto-optical interaction. The results of two cavities with different slot widths show that the coupling strength is dependent on the slot width. It is expected to achieve a strong acousto-optical/optomechanical coupling in air-slot phoxonic crystal structures by utilizing surface acoustic modes. - Highlights: • Two-dimensional air-slot phoxonic crystal cavities which can confine simultaneously optical and acoustic waves are proposed. • The acoustic and optical waves are highly confined near/in the air-slot. • The high overlap of the photonic and phononic cavity modes significantly enhances the moving interface effect. • Different factors which affect the acousto-optical coupling are discussed.

  7. Acoustic absorption of natural gas compression facility enclosures

    Energy Technology Data Exchange (ETDEWEB)

    Lassen, P.; Wong, G. [Noise Management Ltd., Calgary, AB (Canada)

    2009-07-01

    Noise sources at gas compressor facilities include the enclosure/building housing a gas engine and compressor, the ventilation openings, doors and windows for the enclosure, the engine air intake and exhaust, and a cooler. Accurate predictions of the noise levels inside the enclosure, the breakout noise from open windows and doors and ventilation, as well as the transmission through the walls, is necessary in order to determine cost effective noise mitigation for the facility. In order to accurately predict the sound breakout from these facilities it is necessary to know the acoustic absorption of the interior of these equipment enclosures. Although the acoustic absorption data of the wall systems may be available, the absorption attributable to the non-enclosure surfaces, the equipment and fittings, is not usually known and is difficult to predict. Since piping, instrumentation and mechanical equipment often take on a typical arrangement, shape, volumetric density and material composition, it is useful to know the typical acoustic absorption attributable to these items. In this study, reverberation time (RT) measurements were taken at 2 decommissioned gas compressor facilities in order to determine the absorption characteristics of the enclosure. The RT was measured according to ASTM C423-02a. The overall absorption coefficient of a compressor enclosure with a solid liner was found to be similar to that of steel decking. Fittings within the enclosure did not increase the high frequency absorption of the enclosure. It was concluded that room modes, structural vibrations, and fittings may serve to increase the effective absorption at frequencies below 630 Hz. Because of the small dimensions of the enclosure, low-frequency response of the room affected the reliability of the data below 160Hz. Structural vibration of the enclosure was investigated, and may considerably influence the noise breakout from the enclosure apart from the interior acoustical considerations. 4

  8. Acoustic absorption of natural gas compression facility enclosures

    International Nuclear Information System (INIS)

    Lassen, P.; Wong, G.

    2009-01-01

    Noise sources at gas compressor facilities include the enclosure/building housing a gas engine and compressor, the ventilation openings, doors and windows for the enclosure, the engine air intake and exhaust, and a cooler. Accurate predictions of the noise levels inside the enclosure, the breakout noise from open windows and doors and ventilation, as well as the transmission through the walls, is necessary in order to determine cost effective noise mitigation for the facility. In order to accurately predict the sound breakout from these facilities it is necessary to know the acoustic absorption of the interior of these equipment enclosures. Although the acoustic absorption data of the wall systems may be available, the absorption attributable to the non-enclosure surfaces, the equipment and fittings, is not usually known and is difficult to predict. Since piping, instrumentation and mechanical equipment often take on a typical arrangement, shape, volumetric density and material composition, it is useful to know the typical acoustic absorption attributable to these items. In this study, reverberation time (RT) measurements were taken at 2 decommissioned gas compressor facilities in order to determine the absorption characteristics of the enclosure. The RT was measured according to ASTM C423-02a. The overall absorption coefficient of a compressor enclosure with a solid liner was found to be similar to that of steel decking. Fittings within the enclosure did not increase the high frequency absorption of the enclosure. It was concluded that room modes, structural vibrations, and fittings may serve to increase the effective absorption at frequencies below 630 Hz. Because of the small dimensions of the enclosure, low-frequency response of the room affected the reliability of the data below 160Hz. Structural vibration of the enclosure was investigated, and may considerably influence the noise breakout from the enclosure apart from the interior acoustical considerations. 4

  9. Acoustic levitator for containerless measurements on low temperature liquids

    Energy Technology Data Exchange (ETDEWEB)

    Benmore, Chris J [Argonne National Laboratory (ANL); Weber, Richard [Argonne National Laboratory (ANL); Neuefeind, Joerg C [ORNL; Rey, Charles A A [Charles Ray, Inc.

    2009-01-01

    A single-axis acoustic levitator was constructed and used to levitate liquid and solid drops at temperatures from -40 to +40 C. The levitator consisted of: (i) two acoustic transducers mounted on a rigid vertical support that was bolted to an optical breadboard, (ii) a acoustic power supply that controlled acoustic intensity, relative phase of the drive to the transducers, and could modulate the acoustic forces at frequencies up to 1kHz, (iii) a video camera, and (iv) a system for providing a stream of controlled temperature gas flow over the sample. The acoustic transducers were operated at their resonant frequency of ~ 22 kHz and could produce sound pressure levels up to 160 dB. The force applied by the acoustic field could be modulated using a frequency generator to excite oscillations in the sample. Sample temperature was controlled using a modified Cryostream Plus and measured using thermocouples and an infrared thermal imager. The levitator was installed at x-ray beamline 11 ID-C at the Advanced Photon Source and used to investigate the structure of supercooled liquids.

  10. In situ evaluation of density, viscosity, and thickness of adsorbed soft layers by combined surface acoustic wave and surface plasmon resonance.

    Science.gov (United States)

    Francis, Laurent A; Friedt, Jean-Michel; Zhou, Cheng; Bertrand, Patrick

    2006-06-15

    We show the theoretical and experimental combination of acoustic and optical methods for the in situ quantitative evaluation of the density, the viscosity, and the thickness of soft layers adsorbed on chemically tailored metal surfaces. For the highest sensitivity and an operation in liquids, a Love mode surface acoustic wave (SAW) sensor with a hydrophobized gold-coated sensing area is the acoustic method, while surface plasmon resonance (SPR) on the same gold surface as the optical method is monitored simultaneously in a single setup for the real-time and label-free measurement of the parameters of adsorbed soft layers, which means for layers with a predominant viscous behavior. A general mathematical modeling in equivalent viscoelastic transmission lines is presented to determine the correlation between experimental SAW signal shifts and the waveguide structure including the presence of the adsorbed layer and the supporting liquid from which it segregates. A methodology is presented to identify from SAW and SPR simulations the parameters representatives of the soft layer. During the absorption of a soft layer, thickness or viscosity changes are observed in the experimental ratio of the SAW signal attenuation to the SAW signal phase and are correlated with the theoretical model. As application example, the simulation method is applied to study the thermal behavior of physisorbed PNIPAAm, a polymer whose conformation is sensitive to temperature, under a cycling variation of temperature between 20 and 40 degrees C. Under the assumption of the bulk density and the bulk refractive index of PNIPAAm, thickness and viscosity of the film are obtained from simulations; the viscosity is correlated to the solvent content of the physisorbed layer.

  11. Density-near-zero using the acoustically induced transparency of a Fano acoustic resonator

    KAUST Repository

    Elayouch, A.

    2017-01-05

    We report experimental results of near-zero mass density involving an acoustic metamaterial supporting Fano resonance. For this, we designed and fabricated an acoustic resonator with two closely coupled modes and measured its transmission properties. Our study reveals that the phenomenon of acoustically induced transparency is accompanied by an effect of near-zero density. Indeed, the dynamic effective parameters obtained from experimental data show the presence of a frequency band where the effective mass density is close to zero, with high transmission levels reaching 0.7. Furthermore, we demonstrate that such effective parameters lead to wave guiding in a 90-degrees-bent channel. This kind of acoustic metamaterial can, therefore, give rise to acoustic functions like controlling the wavefront, which may lead to very promising applications in acoustic cloacking or imaging.

  12. Surface Acoustic Wave Tag-Based Coherence Multiplexing

    Science.gov (United States)

    Youngquist, Robert C. (Inventor); Malocha, Donald (Inventor); Saldanha, Nancy (Inventor)

    2016-01-01

    A surface acoustic wave (SAW)-based coherence multiplexing system includes SAW tags each including a SAW transducer, a first SAW reflector positioned a first distance from the SAW transducer and a second SAW reflector positioned a second distance from the SAW transducer. A transceiver including a wireless transmitter has a signal source providing a source signal and circuitry for transmitting interrogation pulses including a first and a second interrogation pulse toward the SAW tags, and a wireless receiver for receiving and processing response signals from the SAW tags. The receiver receives scrambled signals including a convolution of the wideband interrogation pulses with response signals from the SAW tags and includes a computing device which implements an algorithm that correlates the interrogation pulses or the source signal before transmitting against the scrambled signals to generate tag responses for each of the SAW tags.

  13. Acoustic observations of internal tides and tidal currents in shallow water.

    Science.gov (United States)

    Turgut, Altan; Mignerey, Peter C; Goldstein, David J; Schindall, Jeffrey A

    2013-04-01

    Significant acoustic travel-time variability and frequency shifts of acoustic intensity level curves in broadband signal spectrograms were measured in the East China Sea during the summer of 2008. The broadband pulses (270-330 Hz) were transmitted from a fixed source and received at a bottomed horizontal array, located at the 33 km range. The acoustic intensity level curves of the received signals indicate regular frequency shifts that are well correlated with the measured internal tides. Similarly, regular travel-time shifts of the acoustic mode arrivals correlate well with the barotropic tides and can be explained by tidal currents along the acoustic propagation track. These observations indicate the potential of monitoring internal tides and tidal currents using low-frequency acoustic signals propagating at long ranges.

  14. Physics of thermo-acoustic sound generation

    Science.gov (United States)

    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.

  15. Detection method of internal leakage from valve using acoustic method

    International Nuclear Information System (INIS)

    Kumagai, Horomichi

    1990-01-01

    The purpose of this study is to estimate the availability of acoustic method for detecting the internal leakage of valves at power plants. Experiments have been carried out on the characteristics of acoustic noise caused by the leak simulated flow. From the experimental results, the mechanism of the acoustic noisegenerated from flow, the relation between acoustic intensity and leak flow velocity, and the characteristics of the acoustic frequency spectrum were clarified. The acoustic method was applied to valves at site, and the background noises were measured in abnormal plant conditions. When the background level is higher than the acoustic signal, the difference between the background noise frequency spectrum and the acoustic signal spectrum provide a very useful leak detection method. (author)

  16. Topological Acoustics

    Science.gov (United States)

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-01

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.

  17. Control of deviations and prediction of surface roughness from micro machining of THz waveguides using acoustic emission signals

    Science.gov (United States)

    Griffin, James M.; Diaz, Fernanda; Geerling, Edgar; Clasing, Matias; Ponce, Vicente; Taylor, Chris; Turner, Sam; Michael, Ernest A.; Patricio Mena, F.; Bronfman, Leonardo

    2017-02-01

    By using acoustic emission (AE) it is possible to control deviations and surface quality during micro milling operations. The method of micro milling is used to manufacture a submillimetre waveguide where micro machining is employed to achieve the required superior finish and geometrical tolerances. Submillimetre waveguide technology is used in deep space signal retrieval where highest detection efficiencies are needed and therefore every possible signal loss in the receiver has to be avoided and stringent tolerances achieved. With a sub-standard surface finish the signals travelling along the waveguides dissipate away faster than with perfect surfaces where the residual roughness becomes comparable with the electromagnetic skin depth. Therefore, the higher the radio frequency the more critical this becomes. The method of time-frequency analysis (STFT) is used to transfer raw AE into more meaningful salient signal features (SF). This information was then correlated against the measured geometrical deviations and, the onset of catastrophic tool wear. Such deviations can be offset from different AE signals (different deviations from subsequent tests) and feedback for a final spring cut ensuring the geometrical accuracies are met. Geometrical differences can impact on the required transfer of AE signals (change in cut off frequencies and diminished SNR at the interface) and therefore errors have to be minimised to within 1 μm. Rules based on both Classification and Regression Trees (CART) and Neural Networks (NN) were used to implement a simulation displaying how such a control regime could be used as a real time controller, be it corrective measures (via spring cuts) over several initial machining passes or, with a micron cut introducing a level plain measure for allowing setup corrective measures (similar to a spirit level).

  18. Propellant injection strategy for suppressing acoustic combustion instability

    Science.gov (United States)

    Diao, Qina

    Shear-coaxial injector elements are often used in liquid-propellant-rocket thrust chambers, where combustion instabilities remain a significant problem. A conventional solution to the combustion instability problem relies on passive control techniques that use empirically-developed hardware such as acoustic baffles and tuned cavities. In addition to adding weight and decreasing engine performance, these devices are designed using trial-and-error methods, which do not provide the capability to predict the overall system stability characteristics in advance. In this thesis, two novel control strategies that are based on propellant fluid dynamics were investigated for mitigating acoustic instability involving shear-coaxial injector elements. The new control strategies would use a set of controlled injectors allowing local adjustment of propellant flow patterns for each operating condition, particularly when instability could become a problem. One strategy relies on reducing the oxidizer-fuel density gradient by blending heavier methane with the main fuel, hydrogen. Another strategy utilizes modifying the equivalence ratio to affect the acoustic impedance through mixing and reaction rate changes. The potential effectiveness of these strategies was assessed by conducting unit-physics experiments. Two different model combustors, one simulating a single-element injector test and the other a double-element injector test, were designed and tested for flame-acoustic interaction. For these experiments, the Reynolds number of the central oxygen jet was kept between 4700 and 5500 making the injector flames sufficiently turbulent. A compression driver, mounted on one side of the combustor wall, provided controlled acoustic excitation to the injector flames, simulating the initial phase of flame-acoustic interaction. Acoustic excitation was applied either as band-limited white noise forcing between 100 Hz and 5000 Hz or as single-frequency, fixed-amplitude forcing at 1150 Hz

  19. Imaging of microwave-induced acoustic fields in LiNbO{sub 3} by high-performance Brillouin microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, B [Lab. Europeen de Recherche Univ.: Saarland-Lorraine, Univ. des Saarlandes, D-66041 Saarbruecken (Germany)]|[Lab. de Physique des Milieux Ionises et Applications, CNRS-UMR 7040, Univ. H. Poincare, Nancy I, F-54506 (France); Krueger, J K [Lab. Europeen de Recherche Univ.: Saarland-Lorraine, Univ. des Saarlandes, D-66041 Saarbruecken (Germany)]|[Fachrichtung 7.2, Experimentalphysik, Univ. des Saarlandes, Bau 38, D-66041 Saarbruecken (Germany); Elmazria, O [Laboratoire Europeen de Recherche Universitaire: Saarland-Lorraine, Universitaet des Saarlandes, D-66041 Saarbruecken (Germany)]|[Laboratoire de Physique des Milieux Ionises et Applications, CNRS-UMR 7040, Universite H. Poincare, Nancy I, F-54506 (France); Bouvot, L [Laboratoire Europeen de Recherche Universitaire: Saarland-Lorraine, Universitaet des Saarlandes, D-66041 Saarbruecken (Germany)]|[Laboratoire de Physique des Milieux Ionises et Applications, CNRS-UMR 7040, Universite H. Poincare, Nancy I, F-54506 (France); Mainka, J [Laboratoire Europeen de Recherche Universitaire: Saarland-Lorraine, Universitaet des Saarlandes, D-66041 Saarbruecken (Germany)]|[Fachrichtung 7.2, Experimentalphysik, Universitaet des Saarlandes, Bau 38, D-66041 Saarbruecken (Germany); Sanctuary, R [Laboratoire Europeen de Recherche Universitaire: Saarland-Lorraine, Universitaet des Saarlandes, D-66041 Saarbruecken (Germany)]|[Laboratoire de Physique des Materiaux, Campus Luxembourg-Limpertsberg, L-1511 Luxembourg (Luxembourg); Rouxel, D [Lab. Europeen de Recherche Univ.: Saarland-Lorraine, Univ. des Saarlandes, D-66041 Saarbruecken (Germany)]|[Lab. de Physique des Milieux Ionises et Applications, CNRS-UMR 7040, Univ. H. Poincare, Nancy I, F-54506 (France); Alnot, P [Lab. Europeen de Recherche Univ.: Saarland-Lorraine, Univ. des Saarlandes, D-66041 Saarbruecken (Germany)]|[Lab. de Physique des Milieux Ionises et Applications, CNRS-UMR 7040, Univ. H. Poincare, Nancy I, F-54506 (France)

    2005-06-21

    High performance Brillouin microscopy (BM) has been used to characterize the spatial distribution of piezoelectrically induced acoustic fields excited at microwave frequencies in a LiNbO{sub 3} single crystal. It is demonstrated that under suitable conditions BM is able to detect microwave-induced bulk as well as surface acoustic waves. Brillouin spectroscopy is able to probe sound wave intensities of induced phonons, which are as small as those of thermal phonons.

  20. Flame synthesis of carbon nano-onions enhanced by acoustic modulation

    Energy Technology Data Exchange (ETDEWEB)

    Chung, De-Hua; Lin, Ta-Hui [Department of Mechanical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Hou, Shuhn-Shyurng, E-mail: sshou@mail.ksu.edu.tw [Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2010-10-29

    Ethylene jet diffusion flames modulated by acoustic excitation in an atmospheric environment were used to synthesize carbon nano-onions (CNOs) on a catalytic nickel substrate. The formation of CNOs was significantly enhanced by acoustic excitation at frequencies near either the natural flickering frequency or the acoustically resonant frequency. The rate of yield of CNOs was high at 10 and 20 Hz (near the natural flickering frequency) for a sampling position z = 5 mm above the burner exit where the gas temperature was about 450-520 deg. C, or at 10, 20 and 30 Hz for z = 10 mm with the gas temperature ranging from 420 to 500 deg. C. Additionally, for both z = 5 and 10 mm, a quantity of CNOs can be obtained at 60-70 Hz, near the acoustically resonant frequency, where the gas temperature was between 620 and 720 deg. C. Almost no CNOs were produced for the other frequencies due to low temperature or lack of carbon sources. CNOs synthesized at low frequencies had a greater diameter and a higher degree of graphitization than those at high frequencies.

  1. Versatile resonance-tracking circuit for acoustic levitation experiments.

    Science.gov (United States)

    Baxter, K; Apfel, R E; Marston, P L

    1978-02-01

    Objects can be levitated by radiation pressure forces in an acoustic standing wave. In many circumstances it is important that the standing wave frequency remain locked on an acoustic resonance despite small changes in the resonance frequency. A self-locking oscillator circuit is described which tracks the resonance frequency by sensing the magnitude of the transducer current. The tracking principle could be applied to other resonant systems.

  2. A non-destructive surface burn detection method for ferrous metals based on acoustic emission and ensemble empirical mode decomposition: from laser simulation to grinding process

    International Nuclear Information System (INIS)

    Yang, Zhensheng; Wu, Haixi; Yu, Zhonghua; Huang, Youfang

    2014-01-01

    Grinding is usually done in the final finishing of a component. As a result, the surface quality of finished products, e.g., surface roughness, hardness and residual stress, are affected by the grinding procedure. However, the lack of methods for monitoring of grinding makes it difficult to control the quality of the process. This paper focuses on the monitoring approaches for the surface burn phenomenon in grinding. A non-destructive burn detection method based on acoustic emission (AE) and ensemble empirical mode decomposition (EEMD) was proposed for this purpose. To precisely extract the AE features caused by phase transformation during burn formation, artificial burn was produced to mimic grinding burn by means of laser irradiation, since laser-induced burn involves less mechanical and electrical noise. The burn formation process was monitored by an AE sensor. The frequency band ranging from 150 to 400 kHz was believed to be related to surface burn formation in the laser irradiation process. The burn-sensitive frequency band was further used to instruct feature extraction during the grinding process based on EEMD. Linear classification results evidenced a distinct margin between samples with and without surface burn. This work provides a practical means for grinding burn detection. (paper)

  3. Ion-acoustic plasma turbulence

    International Nuclear Information System (INIS)

    Bychenkov, V.Y.; Silin, V.P.

    1982-01-01

    A theory is developed of the nonlinear state that is established in a plasma as a result of development of ion-acoustic instability. Account is taken simultaneously of the linear induced scattering of the waves by the ions and of the quasilinear relaxation of the electrons by the ion-acoustic pulsations. The distribution of the ion-acoustic turbulence in frequency and in angle is obtained. An Ohm's law is established and expressions are obtained for the electronic heat flux and for the relaxation time of the electron temperature in a turbulent plasma. Anomalously large absorption and scattering of the electromagnetic waves by the ion-acoustic pulsations is predicted

  4. Advanced numerical technique for analysis of surface and bulk acoustic waves in resonators using periodic metal gratings

    Science.gov (United States)

    Naumenko, Natalya F.

    2014-09-01

    A numerical technique characterized by a unified approach for the analysis of different types of acoustic waves utilized in resonators in which a periodic metal grating is used for excitation and reflection of such waves is described. The combination of the Finite Element Method analysis of the electrode domain with the Spectral Domain Analysis (SDA) applied to the adjacent upper and lower semi-infinite regions, which may be multilayered and include air as a special case of a dielectric material, enables rigorous simulation of the admittance in resonators using surface acoustic waves, Love waves, plate modes including Lamb waves, Stonely waves, and other waves propagating along the interface between two media, and waves with transient structure between the mentioned types. The matrix formalism with improved convergence incorporated into SDA provides fast and robust simulation for multilayered structures with arbitrary thickness of each layer. The described technique is illustrated by a few examples of its application to various combinations of LiNbO3, isotropic silicon dioxide and silicon with a periodic array of Cu electrodes. The wave characteristics extracted from the admittance functions change continuously with the variation of the film and plate thicknesses over wide ranges, even when the wave nature changes. The transformation of the wave nature with the variation of the layer thicknesses is illustrated by diagrams and contour plots of the displacements calculated at resonant frequencies.

  5. Resonant magneto-acoustic switching: influence of Rayleigh wave frequency and wavevector

    Science.gov (United States)

    Kuszewski, P.; Camara, I. S.; Biarrotte, N.; Becerra, L.; von Bardeleben, J.; Savero Torres, W.; Lemaître, A.; Gourdon, C.; Duquesne, J.-Y.; Thevenard, L.

    2018-06-01

    We show on in-plane magnetized thin films that magnetization can be switched efficiently by 180 degrees using large amplitude Rayleigh waves travelling along the hard or easy magnetic axis. Large characteristic filament-like domains are formed in the latter case. Micromagnetic simulations clearly confirm that this multi-domain configuration is compatible with a resonant precessional mechanism. The reversed domains are in both geometries several hundreds of , much larger than has been shown using spin transfer torque- or field-driven precessional switching. We show that surface acoustic waves can travel at least 1 mm before addressing a given area, and can interfere to create magnetic stripes that can be positioned with a sub-micronic precision.

  6. Evoked acoustic emission

    DEFF Research Database (Denmark)

    Elberling, C; Parbo, J; Johnsen, N J

    1985-01-01

    Stimulated acoustic emissions were recorded in response to tonal stimuli at 60 dB p.e. SPL in a small group of normal-hearing adults. Power spectral analysis reveals that the evoked activity from each ear contains energy in preferential frequency bands and the change of stimulus frequency has only...

  7. Gas loading of graphene-quartz surface acoustic wave devices

    Science.gov (United States)

    Whitehead, E. F.; Chick, E. M.; Bandhu, L.; Lawton, L. M.; Nash, G. R.

    2013-08-01

    Graphene was transferred to the propagation path of quartz surface acoustic wave devices and the attenuation due to gas loading of air and argon measured at 70 MHz and 210 MHz and compared to devices with no graphene. Under argon loading, there was no significant difference between the graphene and non-graphene device and the values of measured attenuation agree well with those calculated theoretically. Under air loading, at 210 MHz, there was a significant difference between the non-graphene and graphene devices, with the average value of attenuation obtained with the graphene devices being approximately twice that obtained from the bare quartz devices.

  8. Vibro-acoustics

    CERN Document Server

    Nilsson, Anders

    2015-01-01

    This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and inter...

  9. Frequency-Wavenumber (FK)-Based Data Selection in High-Frequency Passive Surface Wave Survey

    Science.gov (United States)

    Cheng, Feng; Xia, Jianghai; Xu, Zongbo; Hu, Yue; Mi, Binbin

    2018-04-01

    Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of "crossed" artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the "crossed" artifacts. We prove that the "crossed" artifacts would cross the true surface wave energy at fixed points in the f-v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the "crossed" artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach.

  10. Frequency-Wavenumber (FK)-Based Data Selection in High-Frequency Passive Surface Wave Survey

    Science.gov (United States)

    Cheng, Feng; Xia, Jianghai; Xu, Zongbo; Hu, Yue; Mi, Binbin

    2018-07-01

    Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of "crossed" artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the "crossed" artifacts. We prove that the "crossed" artifacts would cross the true surface wave energy at fixed points in the f- v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the "crossed" artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach.

  11. The effect of post-annealing on surface acoustic wave devices based on ZnO thin films prepared by magnetron sputtering

    International Nuclear Information System (INIS)

    Phan, Duy-Thach; Chung, Gwiy-Sang

    2011-01-01

    Zinc oxide (ZnO) thin films were deposited on unheated silicon substrates via radio frequency (RF) magnetron sputtering, and the post-deposition annealing of the ZnO thin films was performed at 400 deg. C, 600 deg. C, 800 deg. C, and 1000 deg. C. The characteristics of the thin films were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The films were then used to fabricate surface acoustic wave (SAW) resonators. The effects of post-annealing on the SAW devices are discussed in this work. Resulting in the 600 deg. C is determined as optimal annealing temperature for SAW devices. At 400 deg. C, the microvoids exit between the grains yield large root mean square (RMS) surface roughness and higher insertion losses in SAW devices. The highest RMS surface roughness, crack and residual stress cause a reduction of surface velocity (about 40 m/s) and increase dramatically insertion loss at 1000 deg. C. The SAW devices response becomes very weak at this temperature, the electromechanical coupling coefficient (k 2 ) of ZnO film decrease from 3.8% at 600 deg. C to 1.49% at 1000 deg. C.

  12. Frequency Characteristics of Surface Wave Generated by Single-Line Pulsed Laser Beam with Two Kinds of Spatial Energy Profile Models: Gaussian and Square-Like

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Ho Geon; Kim, Myung Hwan; Choi, Sung Ho; Kim, Chung Seok; Jhang, Kyung Young [Hanyang University, Seoul (Korea, Republic of)

    2012-08-15

    Using a single-line pulsed laser beam is well known as a useful noncontact method to generate a directional surface acoustic wave. In this method, different laser beam energy profiles produce different waveforms and frequency characteristics. In this paper, we considered two typical kinds of laser beam energy profiles, Gaussian and square-like, to find out a difference in the frequency characteristics. To achieve this, mathematical models were proposed first for Gaussian laser beam profile and square-like respectively, both of which depended on the laser beam width. To verify the theoretical models, experimental setups with a cylindrical lens and a line-slit mask were respectively designed to produce a line laser beam with Gaussian spatial energy profile and square-like. The frequency responses of the theoretical models showed good agreement with experimental results in terms of the existence of harmonic frequency components and the shift of the first peak frequencies to low.

  13. Rapid generation of protein aerosols and nanoparticles via surface acoustic wave atomization

    International Nuclear Information System (INIS)

    Alvarez, Mar; Friend, James; Yeo, Leslie Y

    2008-01-01

    We describe the fabrication of a surface acoustic wave (SAW) atomizer and show its ability to generate monodisperse aerosols and particles for drug delivery applications. In particular, we demonstrate the generation of insulin liquid aerosols for pulmonary delivery and solid protein nanoparticles for transdermal and gastrointestinal delivery routes using 20 MHz SAW devices. Insulin droplets around 3 μm were obtained, matching the optimum range for maximizing absorption in the alveolar region. A new approach is provided to explain these atomized droplet diameters by returning to fundamental physical analysis and considering viscous-capillary and inertial-capillary force balance rather than employing modifications to the Kelvin equation under the assumption of parametric forcing that has been extended to these frequencies in past investigations. In addition, we consider possible mechanisms by which the droplet ejections take place with the aid of high-speed flow visualization. Finally, we show that nanoscale protein particles (50-100 nm in diameter) were obtained through an evaporative process of the initial aerosol, the final size of which could be controlled merely by modifying the initial protein concentration. These results illustrate the feasibility of using SAW as a novel method for rapidly producing particles and droplets with a controlled and narrow size distribution.

  14. Terahertz plasmon and surface-plasmon modes in cylindrical metallic nanowires

    International Nuclear Information System (INIS)

    Wu Ping; Xu Wen; Li Long-Long; Lu Tie-Cheng; Wu Wei-Dong

    2014-01-01

    We present a theoretical study on collective excitation modes associated with plasmon and surface-plasmon oscillations in cylindrical metallic nanowires. Based on a two-subband model, the dynamical dielectric function matrix is derived under the random-phase approximation. An optic-like branch and an acoustic-like branch, which are free of Landau damping, are observed for both plasmon and surface-plasmon modes. Interestingly, for surface-plasmon modes, we find that two branches of the dispersion relation curves converge at a wavevector q z = q max beyond which no surface-plasmon mode exists. Moreover, we examine the dependence of these excitation modes on sample parameters such as the radius of the nanowires. It is found that in metallic nanowires realized by state-of-the-art nanotechnology the intra- and inter-subband plasmon and surface-plasmon frequencies are in the terahertz bandwidth. The frequency of the optic-like modes decreases with increasing radius of the nanowires, whereas that of the acoustic-like modes is not sensitive to the variation of the radius. This study is pertinent to the application of metallic nanowires as frequency-tunable terahertz plasmonic devices. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  15. Broadband manipulation of refracted wavefronts by gradient acoustic metasurface with V-shape structure

    Science.gov (United States)

    Lan, Jun; Li, Yifeng; Liu, Xiaozhou

    2017-12-01

    We present a space folding acoustic metasurface with a V-shaped structure, which exhibits ultra-broadband and high efficiency transmission compared to previously investigated space folding metasurfaces. The proposal employs a gradient refractive index profile to redirect the refracted wave arbitrarily and an existence of air channels with direct sound propagation to improve impedance matching between the metasurface and the background medium. As expected from frequency-independent generalized Snell's law, the demonstrated acoustic metasurface can steer refracted wavefronts at will, including anomalous refraction, non-diffracting Bessel beam, sub-wavelength flat lens, and conversion of the propagating wave into the surface wave. The designed V-shape metasurface overcomes the limitation of narrowband, which may offer potential applications in medical ultrasound imaging and broadband acoustical devices.

  16. Ion acoustic waves in the solar wind

    International Nuclear Information System (INIS)

    Gurnett, D.A.; Frank, L.A.

    1978-01-01

    Plasma wave measurements on the Helios I and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the Imp 6 spacecraft now provide strong evidence that these waves are short-wavelength ion acoustic waves which are Doppler-shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting Imp 6 and 8 spacecraft shows that the ion acoustic turbulence detected in interplanetary space has characteristics essentially identical to those of bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases, enhanced ion acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as was suggested by Forslund. Possible related mechanisms which could explain the generation of ion acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered

  17. Acoustic resonances of fluid-immersed elastic cylinders and spheroids: Theory and experiment

    Science.gov (United States)

    Niemiec, Jan; Überall, Herbert; Bao, X. L.

    2002-05-01

    Frequency resonances in the scattering of acoustic waves from a target object are caused by the phase matching of surface waves repeatedly encircling the object. This is exemplified here by considering elastic finite cylinders and spheroids, and the phase-matching condition provides a means of calculating the complex resonance frequencies of such objects. Tank experiments carried out at Catholic University, or at the University of Le Havre, France by G. Maze and J. Ripoche, have been interpreted using this approach. The experiments employed sound pulses to measure arrival times, which allowed identification of the surface paths taken by the surface waves, thus giving rise to resonances in the scattering amplitude. A calculation of the resonance frequencies using the T-matrix approach showed satisfactory agreement with the experimental resonance frequencies that were either measured directly (as at Le Havre), or that were obtained by the interpretation of measured arrival times (at Catholic University) using calculated surface wave paths, and the extraction of resonance frequencies therefrom, on the basis of the phase-matching condition. Results for hemispherically endcapped, evacuated steel cylinders obtained in a lake experiment carried out by the NSWC were interpreted in the same fashion.

  18. Characteristics Analysis of Joint Acoustic Echo and Noise Suppression in Periodic Drillstring Waveguide

    Directory of Open Access Journals (Sweden)

    Li Cheng

    2014-01-01

    Full Text Available A new method of wireless data telemetry used by oil industry uses compressional acoustic waves to transmit downhole information from the bottom hole to the surface. Unfortunately, acoustic echoes and drilling vibration noises in periodic drillstring are a major issue in transmission performance. A combined acoustic echo and noise suppression method based on wave motion characteristic in drillstring is adopted to enhance an upward-going transmitted acoustic signal. The presented scheme consists of a primary acoustic echo canceller using an array of two accelerometers for dealing with the downward-going noises and a secondary acoustic insulation structure for restraining the upward-going vibration noises. Furthermore, the secondary acoustic insulation structure exhibits a banded and dispersive spectral structure because of periodic groove configuration. By using a finite-differential algorithm for the one-dimensional propagation of longitudinal waves, acoustic receiving characteristics of transmitted signals are simulated with additive Gaussian noise in a periodic pipe structure of limited length to investigate the effects on transmission performance optimization. The results reveal that the proposed scheme can achieve a much lower error bit ratio over a specified acoustic isolation frequency range with a 30–40 dB reduction in the average noise level compared to traditional single-receiver scheme.

  19. Study on the performance of ZnO nanomaterial-based surface acoustic wave ultraviolet detectors

    International Nuclear Information System (INIS)

    Peng, Wenbo; He, Yongning; Zhao, Xiaolong; Liu, Han; Kang, Xue; Wen, Changbao

    2013-01-01

    A ZnO nanomaterial-based surface acoustic wave (SAW) ultraviolet (UV) detector is highly desirable for UV radiation detection due to its high sensitivity. In this work, firstly the ZnO nanomaterial-based SAW UV detectors operating at three different frequencies (∼50, ∼100 and ∼200 MHz) were fabricated. Then, four ZnO nanomaterial sensing layers with different thicknesses were synthesized on the SAW UV detectors operating at ∼200 MHz. The morphology, crystallization and photoluminescence of ZnO nanomaterial sensing layers were characterized using the scanning electron microscopy, transmission electron microscopy, x-ray diffraction and fluorescence spectrometer, respectively. The SAW UV detectors based on different operating frequencies and ZnO nanomaterial sensing layer's thicknesses were exposed under UV illumination at a wavelength of 365 nm and their UV responses were measured. The experimental results indicate that the frequency shift of ZnO nanomaterial-based SAW UV detector can be significantly improved by increasing operating frequency or ZnO nanomaterial sensing layer's thickness. Furthermore, the detectors exhibit good selectivity of UV illumination, an ultrahigh UV sensitivity of about 9.6 ppm (µW cm −2 ) −1  and fast transient properties. The experimental results agree well with the acousto-electric effect theory. What deserves to be noted is that, under a UV intensity of 150 µW cm −2 , the frequency shift of the SAW UV detector operating at ∼50 MHz with a thin ZnO nanomaterial sensing layer was only ∼50 kHz while that of the SAW UV detector operating at ∼200 MHz with a thick ZnO nanomaterial sensing layer could reach ∼292 kHz. These results suggest the huge potential applications of ultra-sensitive ZnO nanomaterial-based SAW UV detectors for remote wireless UV and radiation monitoring. (paper)

  20. Acoustic scaling: A re-evaluation of the acoustic model of Manchester Studio 7

    Science.gov (United States)

    Walker, R.

    1984-12-01

    The reasons for the reconstruction and re-evaluation of the acoustic scale mode of a large music studio are discussed. The design and construction of the model using mechanical and structural considerations rather than purely acoustic absorption criteria is described and the results obtained are given. The results confirm that structural elements within the studio gave rise to unexpected and unwanted low-frequency acoustic absorption. The results also show that at least for the relatively well understood mechanisms of sound energy absorption physical modelling of the structural and internal components gives an acoustically accurate scale model, within the usual tolerances of acoustic design. The poor reliability of measurements of acoustic absorption coefficients, is well illustrated. The conclusion is reached that such acoustic scale modelling is a valid and, for large scale projects, financially justifiable technique for predicting fundamental acoustic effects. It is not appropriate for the prediction of fine details because such small details are unlikely to be reproduced exactly at a different size without extensive measurements of the material's performance at both scales.

  1. Flaw identification using acoustic emission

    International Nuclear Information System (INIS)

    Woodward, B.; McDonald, N.R.

    1975-01-01

    In order to realise the full inspection potential of acoustic emission monitoring, data obtained from zirconium and steel testpieces have been correlated with metallurgical condition and mechanical behaviour, since the nature of emission signatures is strongly affected by the physical characteristics and internal structure of the material. During experiments, signals were tape recorded and the surface of each testpiece was recorded on movie film or videotape so that acoustic and visual information could be correlated. Large numbers of tape-recorded bursts have been analysed with a real time spectrum analyser, and statistical parameters (such as mean energy density, mean frequency and variance) derived from the spectra were calculated by an IBM 360/50 computer and selectively displayed on a line plotter. In the case of zirconium, observed differences in these parameters were an indication that the emission signals were generated by three different metallurgical mechanisms. A movie film of testpiece surface deformation revealed the occurrence of twin initiation, twin broadening and slip. Fracture events either in the zirconium matrix or in second phase particles are also possible although not observed directly. A direct correlation was confirmed between twin initiations and emission signals. Work is proceeding on establishing a different correlation between emission signals and stress corrosion cracks

  2. Determination of the viscous acoustic field for liquid drop positioning/forcing in an acoustic levitation chamber in microgravity

    Science.gov (United States)

    Lyell, Margaret J.

    1992-01-01

    The development of acoustic levitation systems has provided a technology with which to undertake droplet studies as well as do containerless processing experiments in a microgravity environment. Acoustic levitation chambers utilize radiation pressure forces to position/manipulate the drop. Oscillations can be induced via frequency modulation of the acoustic wave, with the modulated acoustic radiation vector acting as the driving force. To account for tangential as well as radial forcing, it is necessary that the viscous effects be included in the acoustic field. The method of composite expansions is employed in the determination of the acoustic field with viscous effects.

  3. Beam paths of flexural Lamb waves at high frequency in the first band within phononic crystal-based acoustic lenses

    Directory of Open Access Journals (Sweden)

    J. Zhao

    2014-12-01

    Full Text Available This work deals with an analytical and numerical study of the focusing of the lowest order anti-symmetric Lamb wave in gradient index phononic crystals. Computing the ray trajectories of the elastic beam allowed us to analyze the lateral dimensions and shape of the focus, either in the inner or behind the phononic crystal-based acoustic lenses, for frequencies within a broad range in the first band. We analyzed and discussed the focusing behaviors inside the acoustic lenses where the focalization at sub-wavelength scale was achieved. The focalization behind the gradient index phononic crystal is shown to be efficient as well: we report on FMHM = 0.63λ at 11MHz.

  4. Evaluation of acoustic resonance at branch section in main steam line. Part 2. Proposal of method for predicting resonance frequency in steam flow

    International Nuclear Information System (INIS)

    Uchiyama, Yuta; Morita, Ryo

    2012-01-01

    Flow-induced acoustic resonances of piping system containing closed side-branches are sometimes encountered in power plants. Acoustic standing waves with large amplitude pressure fluctuation in closed side-branches are excited by the unstable shear layer which separates the mean flow in the main piping from the stagnant fluid in the branch. In U.S. NPP, the steam dryer had been damaged by high cycle fatigue due to acoustic-induced vibration under a power uprating condition. Our previous research developed the method for evaluating the acoustic resonance at the branch sections in actual power plants by using CFD. In the method, sound speed in wet steam is evaluated by its theory on the assumption of homogeneous flow, although it may be different from practical sound speed in wet steam. So, it is necessary to consider and introduce the most suitable model of practical sound speed in wet steam. In addition, we tried to develop simplified prediction method of the amplitude and frequency of pressure fluctuation in wet steam flow. Our previous experimental research clarified that resonance amplitude of fluctuating pressure at the top of the branch in wet steam. However, the resonance frequency in steam condition could not be estimated by using theoretical equation as the end correction in steam condition and sound speed in wet steam is not clarified as same reason as CFD. Therefore, in this study, we tried to evaluate the end correction in each dry and wet steam and sound speed of wet steam from experimental results. As a result, method for predicting resonance frequency by using theoretical equation in each wet and dry steam condition was proposed. (author)

  5. The isolation of low frequency impact sounds in hotel construction

    Science.gov (United States)

    LoVerde, John J.; Dong, David W.

    2002-11-01

    One of the design challenges in the acoustical design of hotels is reducing low frequency sounds from footfalls occurring on both carpeted and hard-surfaced floors. Research on low frequency impact noise [W. Blazier and R. DuPree, J. Acoust. Soc. Am. 96, 1521-1532 (1994)] resulted in a conclusion that in wood construction low frequency impact sounds were clearly audible and that feasible control methods were not available. The results of numerous FIIC (Field Impact Insulation Class) measurements performed in accordance with ASTM E1007 indicate the lack of correlation between FIIC ratings and the reaction of occupants in the room below. The measurements presented include FIIC ratings and sound pressure level measurements below the ASTM E1007 low frequency limit of 100 Hertz, and reveal that excessive sound levels in the frequency range of 63 to 100 Hertz correlate with occupant complaints. Based upon this history, a tentative criterion for maximum impact sound level in the low frequency range is presented. The results presented of modifying existing constructions to reduce the transmission of impact sounds at low frequencies indicate that there may be practical solutions to this longstanding problem.

  6. Evaluation method for acoustic trapping performance by tracking motion of trapped microparticle

    Science.gov (United States)

    Lim, Hae Gyun; Ham Kim, Hyung; Yoon, Changhan

    2018-05-01

    We report a method to evaluate the performances of a single-beam acoustic tweezer using a high-frequency ultrasound transducer. The motion of a microparticle trapped by a 45-MHz single-element transducer was captured and analyzed to deduce the magnitude of trapping force. In the proposed method, the motion of a trapped microparticle was analyzed from a series of microscopy images to compute trapping force; thus, no additional equipment such as microfluidics is required. The method could be used to estimate the effective trapping force in an acoustic tweezer experiment to assess cell membrane deformability by attaching a microbead to the surface of a cell and tracking the motion of the trapped bead, which is similar to a bead-based assay that uses optical tweezers. The results showed that the trapping force increased with increasing acoustic intensity and duty factor, but the force eventually reached a plateau at a higher acoustic intensity. They demonstrated that this method could be used as a simple tool to evaluate the performance and to optimize the operating conditions of acoustic tweezers.

  7. Department of Cybernetic Acoustics

    Science.gov (United States)

    The development of the theory, instrumentation and applications of methods and systems for the measurement, analysis, processing and synthesis of acoustic signals within the audio frequency range, particularly of the speech signal and the vibro-acoustic signal emitted by technical and industrial equipments treated as noise and vibration sources was discussed. The research work, both theoretical and experimental, aims at applications in various branches of science, and medicine, such as: acoustical diagnostics and phoniatric rehabilitation of pathological and postoperative states of the speech organ; bilateral ""man-machine'' speech communication based on the analysis, recognition and synthesis of the speech signal; vibro-acoustical diagnostics and continuous monitoring of the state of machines, technical equipments and technological processes.

  8. PLASTIC PIPE DEFECT DETECTION USING NONLINEAR ACOUSTIC MODULATION

    Directory of Open Access Journals (Sweden)

    Gigih Priyandoko

    2015-02-01

    Full Text Available This project discuss about the defect detection of plastic pipe by using nonlinear acoustic wave modulation method. Nonlinaer acoustic modulations are investigated for fatigue crack detection. It is a sensitive method for damage detection and it is based on the propagation of high frequency acoustic waves in plastic pipe with low frequency excitation. The plastic pipe is excited simultaneously with a slow amplitude modulated vibration pumping wave and a constant amplitude probing wave. The frequency of both the excitation signals coincides with the resonances of the plastic pipe. An actuator is used for frequencies generation while sensor is used for the frequencies detection. Besides that, a PVP pipe is used as the specimen as it is commonly used for the conveyance of liquid in many fields. The results obtained are being observed and the difference between uncrack specimen and cracked specimen can be distinguished.

  9. Micro-Electromechanical Acoustic Resonator Coated with Polyethyleneimine Nanofibers for the Detection of Formaldehyde Vapor

    Directory of Open Access Journals (Sweden)

    Da Chen

    2018-02-01

    Full Text Available We demonstrate a promising strategy to combine the micro-electromechanical film bulk acoustic resonator and the nanostructured sensitive fibers for the detection of low-concentration formaldehyde vapor. The polyethyleneimine nanofibers were directly deposited on the resonator surface by a simple electrospinning method. The film bulk acoustic resonator working at 4.4 GHz acted as a sensitive mass loading platform and the three-dimensional structure of nanofibers provided a large specific surface area for vapor adsorption and diffusion. The ultra-small mass change induced by the absorption of formaldehyde molecules onto the amine groups in polyethyleneimine was detected by measuring the frequency downshift of the film bulk acoustic resonator. The proposed sensor exhibits a fast, reversible and linear response towards formaldehyde vapor with an excellent selectivity. The gas sensitivity and the detection limit were 1.216 kHz/ppb and 37 ppb, respectively. The study offers a great potential for developing sensitive, fast-response and portable sensors for the detection of indoor air pollutions.

  10. Perspective: Acoustic metamaterials in transition

    KAUST Repository

    Wu, Ying

    2017-12-15

    Acoustic metamaterials derive their novel characteristics from the interaction between acoustic waves with designed structures. Since its inception seventeen years ago, the field has been driven by fundamental geometric and physical principles that guide the structure design rules as well as provide the basis for wave functionalities. Recent examples include resonance-based acoustic metasurfaces that offer flexible control of acoustic wave propagation such as focusing and re-direction; parity-time (PT)-symmetric acoustics that utilizes the general concept of pairing loss and gain to achieve perfect absorption at a single frequency; and topological phononics that can provide one-way edge state propagation. However, such novel functionalities are not without constraints. Metasurface elements rely on resonances to enhance their coupling to the incident wave; hence, its functionality is limited to a narrow frequency band. Topological phononics is the result of the special lattice symmetry that must be fixed at the fabrication stage. Overcoming such constraints naturally forms the basis for further developments. We identify two emergent directions: Integration of acoustic metamaterial elements for achieving broadband characteristics as well as acoustic wave manipulation tasks more complex than the single demonstrative functionality; and active acoustic metamaterials that can adapt to environment as well as to go beyond the constraints on the passive acoustic metamaterials. Examples of a successful recent integration of multi-resonators in achieving broadband sound absorption can be found in optimal sound-absorbing structures, which utilize causality constraint as a design tool in realizing the target-set absorption spectrum with a minimal sample thickness. Active acoustic metamaterials have also demonstrated the capability to tune bandgaps as well as to alter property of resonances in real time through stiffening of the spring constants, in addition to the PT symmetric

  11. Acoustic Measurement Of Periodic Motion Of Levitated Object

    Science.gov (United States)

    Watkins, John L.; Barmatz, Martin B.

    1992-01-01

    Some internal vibrations, oscillations in position, and rotations of acoustically levitated object measured by use of microphone already installed in typical levitation chamber for tuning chamber to resonance and monitoring operation. Levitating acoustic signal modulated by object motion of lower frequency. Amplitude modulation detected and analyzed spectrally to determine amplitudes and frequencies of motions.

  12. Selective particle and cell capture in a continuous flow using micro-vortex acoustic streaming.

    Science.gov (United States)

    Collins, David J; Khoo, Bee Luan; Ma, Zhichao; Winkler, Andreas; Weser, Robert; Schmidt, Hagen; Han, Jongyoon; Ai, Ye

    2017-05-16

    Acoustic streaming has emerged as a promising technique for refined microscale manipulation, where strong rotational flow can give rise to particle and cell capture. In contrast to hydrodynamically generated vortices, acoustic streaming is rapidly tunable, highly scalable and requires no external pressure source. Though streaming is typically ignored or minimized in most acoustofluidic systems that utilize other acoustofluidic effects, we maximize the effect of acoustic streaming in a continuous flow using a high-frequency (381 MHz), narrow-beam focused surface acoustic wave. This results in rapid fluid streaming, with velocities orders of magnitude greater than that of the lateral flow, to generate fluid vortices that extend the entire width of a 400 μm wide microfluidic channel. We characterize the forces relevant for vortex formation in a combined streaming/lateral flow system, and use these acoustic streaming vortices to selectively capture 2 μm from a mixed suspension with 1 μm particles and human breast adenocarcinoma cells (MDA-231) from red blood cells.

  13. Optical measurement of acoustic radiation pressure of the near-field acoustic levitation through transparent object

    OpenAIRE

    Nakamura, Satoshi; Furusawa, Toshiaki; Sasao, Yasuhiro; Katsura, Kogure; Naoki, Kondo

    2013-01-01

    It is known that macroscopic objects can be levitated for few to several hundred micrometers by near-field acoustic field and this phenomenon is called near-field acoustic levitation (NFAL). Although there are various experiments conducted to measure integrated acoustic pressure on the object surface, up to now there was no direct method to measure pressure distribution. In this study we measured the acoustic radiation pressure of the near-field acoustic levitation via pressure-sensitive paint.

  14. High efficiency and broadband acoustic diodes

    Science.gov (United States)

    Fu, Congyi; Wang, Bohan; Zhao, Tianfei; Chen, C. Q.

    2018-01-01

    Energy transmission efficiency and working bandwidth are the two major factors limiting the application of current acoustic diodes (ADs). This letter presents a design of high efficiency and broadband acoustic diodes composed of a nonlinear frequency converter and a linear wave filter. The converter consists of two masses connected by a bilinear spring with asymmetric tension and compression stiffness. The wave filter is a linear mass-spring lattice (sonic crystal). Both numerical simulation and experiment show that the energy transmission efficiency of the acoustic diode can be improved by as much as two orders of magnitude, reaching about 61%. Moreover, the primary working band width of the AD is about two times of the cut-off frequency of the sonic crystal filter. The cut-off frequency dependent working band of the AD implies that the developed AD can be scaled up or down from macro-scale to micro- and nano-scale.

  15. Background noise of acoustic emission signals in sodium piping loop

    International Nuclear Information System (INIS)

    Mori, Y.; Aoki, K.; Kuribayashi, K.; Kishi, T.; Sakakibara, Y.

    1985-01-01

    Background noise measurement in the frequency range of acoustic emission (AE) signals was made on the sodium piping loops of a 50 MW steam generator test facility in the Power Reactor and Nuclear Fuel Development Corporation (PNC). During the dynamic characteristics test of the steam generator over a wide range of operating conditions, the background noise generated on the pipe surface was measured using wideband AE sensor externally mounted with waveguide. Data were obtained for the effect of power loads of steam generator on both amplitude and frequency spectra of background noise signals. Source and nature of background noise were established

  16. Acoustic emission intrusion detector

    International Nuclear Information System (INIS)

    Carver, D.W.; Whittaker, J.W.

    1980-01-01

    An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal

  17. Brillouin spectroscopy with surface acoustic waves on intermediate valent, doped SmS

    International Nuclear Information System (INIS)

    Schaerer, U.; Jung, A.; Wachter, P.

    1998-01-01

    Brillouin scattering on surface acoustic waves is a very powerful tool to determine the elastic constants of intermediate valent crystals, since the method is non-destructive and no mechanical contact is needed. A strong evidence for intermediate valence is a negative value of Poisson's ratio, which describes the behavior of the volume under uniaxial pressure. SmS by itself makes a semiconductor-metal transition at a pressure of more than 6.5 kbar. When substituting the divalent Sm by a trivalent cation, like Y, La or Tm, SmS can become - depending on the doping concentration - intermediate valent without any applied, external pressure. In this work, we will present measurements of the velocities of the surface acoustic waves and the calculation of the elastic constants of La- and Tm-doped SmS compounds. We found a clear dependence of Poisson's ratio on the doping concentration and on the valence of the materials. Furthermore, we will discuss the mechanism leading to intermediate valence when substituting Sm. Besides the internal, chemical pressure, which is produced by the built in trivalent cations with their smaller ionic radii, we have clear evidence, that the free electrons in the 5d band, induced by the substituting atoms, also play an important role in making doped SmS intermediate valent. (orig.)

  18. Acoustic Resonance between Ground and Thermosphere

    Directory of Open Access Journals (Sweden)

    M Matsumura

    2009-04-01

    Full Text Available Ultra-low frequency acoustic waves called "acoustic gravity waves" or "infrasounds" are theoretically expected to resonate between the ground and the thermosphere. This resonance is a very important phenomenon causing the coupling of the solid Earth, neutral atmosphere, and ionospheric plasma. This acoustic resonance, however, has not been confirmed by direct observations. In this study, atmospheric perturbations on the ground and ionospheric disturbances were observed and compared with each other to confirm the existence of resonance. Atmospheric perturbations were observed with a barometer, and ionospheric disturbances were observed using the HF Doppler method. An end point of resonance is in the ionosphere, where conductivity is high and the dynamo effect occurs. Thus, geomagnetic observation is also useful, so the geomagnetic data were compared with other data. Power spectral density was calculated and averaged for each month. Peaks appeared at the theoretically expected resonance frequencies in the pressure and HF Doppler data. The frequencies of the peaks varied with the seasons. This is probably because the vertical temperature profile of the atmosphere varies with the seasons, as does the reflection height of infrasounds. These results indicate that acoustic resonance occurs frequently.

  19. Dual-band frequency selective surface with large band separation and stable performance

    Science.gov (United States)

    Zhou, Hang; Qu, Shao-Bo; Peng, Wei-Dong; Lin, Bao-Qin; Wang, Jia-Fu; Ma, Hua; Zhang, Jie-Qiu; Bai, Peng; Wang, Xu-Hua; Xu, Zhuo

    2012-05-01

    A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations.

  20. On-line low and high frequency acoustic leak detection and location for an automated steam generator protection system

    International Nuclear Information System (INIS)

    Gaubatz, D.C.; Gluekler, E.L.

    1990-01-01

    Two on-line acoustic leak detection systems were operated and installed on a 76 MW hockey stick steam generator in the Sodium Components Test Installation (SCTI) at the Energy Technology Engineering Center (ETEC) in Southern California. The low frequency system demonstrated the capability to detect and locate leaks, both intentional and unintentional. No false alarms were issued during the two year test program even with adjacent blasting activities, pneumatic drilling, shuttle rocket engine testing nearby, scrams of the SCTI facility, thermal/hydraulic transient testing, and pump/control valve operations. For the high frequency system the capability to detect water into sodium reactions was established utilizing frequencies as high as 300 kHz. The high frequency system appeared to be sensitive to noise generated by maintenance work and system valve operations. Subsequent development work which is incomplete as of this date showed much more promise for the high frequency system. (author). 13 figs