WorldWideScience

Sample records for acoustic wave sensing

  1. 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.

  2. Acoustic Wave Propagation in Pressure Sense Lines

    Science.gov (United States)

    Vitarius, Patrick; Gregory, Don A.; Wiley, John; Korman, Valentin

    2003-01-01

    Sense lines are used in pressure measurements to passively transmit information from hostile environments to areas where transducers can be used. The transfer function of a sense line can be used to obtain information about the measured environment from the protected sensor. Several properties of this transfer function are examined, including frequency dependence, Helmholtz resonance, and time of flight delay.

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

    Science.gov (United States)

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

    2014-10-15

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

  4. PASSIVE WIRELESS MULTI-SENSOR TEMPERATURE AND PRESSURE SENSING SYSTEM USING 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) sensors and multi-sensor systems for NASA application to remote wireless sensing of...

  5. Acoustic-wave sensor apparatus for analyzing a petroleum-based composition and sensing solidification of constituents therein

    Science.gov (United States)

    Spates, J.J.; Martin, S.J.; Mansure, A.J.

    1997-08-26

    An acoustic-wave sensor apparatus and method are disclosed. The apparatus for analyzing a normally liquid petroleum-based composition includes at least one acoustic-wave device in contact with the petroleum-based composition for sensing or detecting the presence of constituents (e.g. paraffins or petroleum waxes) therein which solidify upon cooling of the petroleum-based composition below a cloud-point temperature. The acoustic-wave device can be a thickness-shear-mode device (also termed a quartz crystal microbalance), a surface-acoustic-wave device, an acoustic-plate-mode device or a flexural plate-wave device. Embodiments of the present invention can be used for measuring a cloud point, a pour point and/or a freeze point of the petroleum-based composition, and for determining a temperature characteristic of each point. Furthermore, measurements with the acoustic-wave sensor apparatus can be made off-line by using a sample having a particular petroleum-based composition; or in-situ with the petroleum-based composition contained within a pipeline or storage tank. The acoustic-wave sensor apparatus has uses in many different petroleum technology areas, including the recovery, transport, storage, refining and use of petroleum and petroleum-based products. 7 figs.

  6. 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.

  7. 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.

  8. A Novel Cell-Based Hybrid Acoustic Wave Biosensor with Impedimetric Sensing Capabilities

    Directory of Open Access Journals (Sweden)

    Ioana Voiculescu

    2013-03-01

    Full Text Available A novel multiparametric biosensor system based on living cells will be presented. The biosensor system includes two biosensing techniques on a single device: resonant frequency measurements and electric cell-substrate impedance sensing (ECIS. The multiparametric sensor system is based on the innovative use of the upper electrode of a quartz crystal microbalance (QCM resonator as working electrode for the ECIS technique. The QCM acoustic wave sensor consists of a thin AT-cut quartz substrate with two gold electrodes on opposite sides. For integration of the QCM with the ECIS technique a semicircular counter electrode was fabricated near the upper electrode on the same side of the quartz crystal. Bovine aortic endothelial live cells (BAECs were successfully cultured on this hybrid biosensor. Finite element modeling of the bulk acoustic wave resonator using COMSOL simulations was performed. Simultaneous gravimetric and impedimetric measurements performed over a period of time on the same cell culture were conducted to validate the device’s sensitivity. The time necessary for the BAEC cells to attach and form a compact monolayer on the biosensor was 35~45 minutes for 1.5 × 104 cells/cm2 BAECs; 60 minutes for 2.0 × 104 cells/cm2 BAECs; 70 minutes for 3.0 × 104 cells/cm2 BAECs; and 100 minutes for 5.0 × 104 cells/cm2 BAECs. It was demonstrated that this time is the same for both gravimetric and impedimetric measurements. This hybrid biosensor will be employed in the future for water toxicity detection.

  9. A Novel Cell-Based Hybrid Acoustic Wave Biosensor with Impedimetric Sensing Capabilities

    Science.gov (United States)

    Liu, Fei; Li, Fang; Nordin, Anis Nurashikin; Voiculescu, Ioana

    2013-01-01

    A novel multiparametric biosensor system based on living cells will be presented. The biosensor system includes two biosensing techniques on a single device: resonant frequency measurements and electric cell-substrate impedance sensing (ECIS). The multiparametric sensor system is based on the innovative use of the upper electrode of a quartz crystal microbalance (QCM) resonator as working electrode for the ECIS technique. The QCM acoustic wave sensor consists of a thin AT-cut quartz substrate with two gold electrodes on opposite sides. For integration of the QCM with the ECIS technique a semicircular counter electrode was fabricated near the upper electrode on the same side of the quartz crystal. Bovine aortic endothelial live cells (BAECs) were successfully cultured on this hybrid biosensor. Finite element modeling of the bulk acoustic wave resonator using COMSOL simulations was performed. Simultaneous gravimetric and impedimetric measurements performed over a period of time on the same cell culture were conducted to validate the device's sensitivity. The time necessary for the BAEC cells to attach and form a compact monolayer on the biosensor was 35∼45 minutes for 1.5 × 104 cells/cm2 BAECs; 60 minutes for 2.0 × 104 cells/cm2 BAECs; 70 minutes for 3.0 × 104 cells/cm2 BAECs; and 100 minutes for 5.0 × 104 cells/cm2 BAECs. It was demonstrated that this time is the same for both gravimetric and impedimetric measurements. This hybrid biosensor will be employed in the future for water toxicity detection. PMID:23459387

  10. Electrostatic ion acoustic waves

    International Nuclear Information System (INIS)

    Hasegawa, A.

    1983-01-01

    In this paper, certain aspects of plasma physics are illustrated through a study of electrostatic ion acoustic waves. The paper consists of three Sections. Section II deals with linear properties of the ion acoustic wave including derivation of the dispersions relation with the effect of Landau damping and of an ambient magnetic field. The section also introduces the excitation processes of the ion acoustic wave due to an electron drift or to a stimulated Brillouin scattering. The nonlinear properties are introduced in Section III and IV. In Section III, incoherent nonlinear effects such as quasilinear and mode-coupling saturations of the instability are discussed. The coherent nonlinear effects such as the generation of ion acoustic solitons, shocks and weak double layers are presented in Section IV. (Auth.)

  11. 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.

  12. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

    Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...

  13. 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...

  14. Distributed acoustic sensing with Michelson interferometer demodulation

    Science.gov (United States)

    Liu, Xiaohui; Wang, Chen; Shang, Ying; Wang, Chang; Zhao, Wenan; Peng, Gangding; Wang, Hongzhong

    2017-09-01

    The distributed acoustic sensing (DAS) has been extensively studied and widely used. A distributed acoustic sensing system based on the unbalanced Michelson interferometer with phase generated carrier (PGC) demodulation was designed and tested. The system could directly obtain the phase, amplitude, frequency response, and location information of sound wave at the same time and measurement at all points along the sensing fiber simultaneously. Experiments showed that the system successfully measured the acoustic signals with a phase-pressure sensitivity about-148 dB (re rad/μPa) and frequency response ripple less than 1.5 dB. The further field experiment showed that the system could measure signals at all points along the sensing fiber simultaneously.

  15. Guided acoustic wave inspection system

    Science.gov (United States)

    Chinn, Diane J.

    2004-10-05

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

  16. Effects of acoustic radiation force and shear waves for absorption and stiffness sensing in ultrasound modulated optical tomography.

    Science.gov (United States)

    Li, Rui; Elson, Daniel S; Dunsby, Chris; Eckersley, Robert; Tang, Meng-Xing

    2011-04-11

    Ultrasound-modulated optical tomography (UOT) combines optical contrast with ultrasound spatial resolution and has great potential for soft tissue functional imaging. One current problem with this technique is the weak optical modulation signal, primarily due to strong optical scattering in diffuse media and minimal acoustically induced modulation. The acoustic radiation force (ARF) can create large particle displacements in tissue and has been shown to be able to improve optical modulation signals. However, shear wave propagation induced by the ARF can be a significant source of nonlocal optical modulation which may reduce UOT spatial resolution and contrast. In this paper, the time evolution of shear waves was examined on tissue mimicking-phantoms exposed to 5 MHz ultrasound and 532 nm optical radiation and measured with a CCD camera. It has been demonstrated that by generating an ARF with an acoustic burst and adjusting both the timing and the exposure time of the CCD measurement, optical contrast and spatial resolution can be improved by ~110% and ~40% respectively when using the ARF rather than 5 MHz ultrasound alone. Furthermore, it has been demonstrated that this technique simultaneously detects both optical and mechanical contrast in the medium and the optical and mechanical contrast can be distinguished by adjusting the CCD exposure time. © 2011 Optical Society of America

  17. Interaction of langmuir and ion acoustic waves

    International Nuclear Information System (INIS)

    Lee, Hee Jae

    1991-01-01

    Interaction of Langmuir and ion acoustic waves in a plasma is described by Landau-Ginzburg type of equation when the group velocity of the Langmuir wave is equal to the wave velocity of ion acoustic wave. (Author)

  18. Scattering Of Nonplanar Acoustic Waves

    Science.gov (United States)

    Gillman, Judith M.; Farassat, F.; Myers, M. K.

    1995-01-01

    Report presents theoretical study of scattering of nonplanar acoustic waves by rigid bodies. Study performed as part of effort to develop means of predicting scattering, from aircraft fuselages, of noise made by rotating blades. Basic approach was to model acoustic scattering by use of boundary integral equation to solve equation by the Galerkin method.

  19. Oscillating nonlinear acoustic shock waves

    DEFF Research Database (Denmark)

    Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth

    2016-01-01

    We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show that at resona......We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....

  20. 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).

  1. Effective Use of Molecular Recognition in Gas Sensing: Results from Acoustic Wave and In-Situ FTIR Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bodenhofer, K,; Gopel, W.; Hierlemann, A.; Ricco, A.J.

    1998-12-09

    To probe directly the analyte/film interactions that characterize molecular recognition in gas sensors, we recorded changes to the in-situ surface vibrational spectra of specifically fictionalized surface acoustic wave (SAW) devices concurrently with analyte exposure and SAW measurement of the extent of sorption. Fourier-lmnsform infrared external- reflectance spectra (FTIR-ERS) were collected from operating 97-MH2 SAW delay lines during exposure to a range of analytes as they interacted with thin-film coatings previously shown to be selective: cyclodextrins for chiral recognition, Ni-camphorates for Lewis bases such as pyridine and organophosphonates, and phthalocyanines for aromatic compounds. In most cases where specific chemical interactions-metal coordination, "cage" compound inclusion, or z stacking-were expected, analyte dosing caused distinctive changes in the IR spectr~ together with anomalously large SAW sensor responses. In contrast, control experiments involving the physisorption of the same analytes by conventional organic polymers did not cause similar changes in the IR spectra, and the SAW responses were smaller. For a given conventional polymer, the partition coefficients (or SAW sensor signals) roughly followed the analyte fraction of saturation vapor pressure. These SAW/FTIR results support earlier conclusions derived from thickness-shear mode resonator data.

  2. Millimeter waves: acoustic and electromagnetic.

    Science.gov (United States)

    Ziskin, Marvin C

    2013-01-01

    This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. Copyright © 2012 Wiley Periodicals, Inc.

  3. Nonlinear positron acoustic solitary waves

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  4. Cylindrical dust acoustic waves with transverse perturbation

    International Nuclear Information System (INIS)

    Xue Jukui

    2003-01-01

    The nonlinear dust acoustic waves in dusty plasmas with the combined effects of bounded cylindrical geometry and the transverse perturbation are studied. Using the perturbation method, a cylindrical Kadomtsev-Petviashvili (CKP) equation that describes the dust acoustic waves is deduced for the first time. A particular solution of this CKP equation is also obtained. It is shown that the dust acoustic solitary waves can exist in the CKP equation

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

    DEFF Research Database (Denmark)

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

    1977-01-01

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

  6. On Collisionless Damping of Ion Acoustic Waves

    DEFF Research Database (Denmark)

    Jensen, Vagn Orla; Petersen, P.I.

    1973-01-01

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

  7. Acoustic parametric pumping of spin waves

    Science.gov (United States)

    Keshtgar, Hedyeh; Zareyan, Malek; Bauer, Gerrit E. W.

    2014-11-01

    Recent experiments demonstrated generation of spin currents by ultrasound. We can understand this acoustically induced spin pumping in terms of the coupling between magnetization and lattice waves. Here we study the parametric excitation of magnetization by longitudinal acoustic waves and calculate the acoustic threshold power. The induced magnetization dynamics can be detected by the spin pumping into an adjacent normal metal that displays the inverse spin Hall effect.

  8. Acoustic parametric pumping of spin waves

    OpenAIRE

    Keshtgar, Hedyeh; Zareyan, Malek; Bauer, Gerrit E. W.

    2013-01-01

    Recent experiments demonstrated generation of spin currents by ultrasound. We can understand this acoustically induced spin pumping in terms of the coupling between magnetization and lattice waves. Here we study the parametric excitation of magnetization by longitudinal acoustic waves and calculate the acoustic threshold power. The induced magnetization dynamics can be detected by the spin pumping into an adjacent normal metal that displays the inverse spin Hall effect.

  9. Distributed Acoustic Sensing (DAS) Array near a Highway for Traffic Monitoring and Near-Surface Shear-Wave Velocity Profiles

    Science.gov (United States)

    Wang, H. F.; Fratta, D.; Lancelle, C.; Ak, E. Ms; Lord, N. E.

    2017-12-01

    Monitoring traffic is important for many technical reasons. It allows for better design of future roads and assessment of the state of current roads. The number, size, weight, and speed of vehicles control deterioration rate. Also, real-time information supplies data to intelligent information systems to help control traffic. Recently there have been studies looking at monitoring traffic seismically as vibrations from traffic are not sensitive to weather and poor visibility. Furthermore, traffic noise can be used to image S-wave velocity distribution in the near surface by capturing and interpreting Rayleigh and Love waves (Nakata, 2016; Zeng et al. 2016). The capability of DAS for high spatial sampling (1 m), temporal sampling (up to 10 kHz), and distributed nature (tens of kilometers) allows for a closer look at the traffic as it passes and how the speed of the vehicle may change over the length of the array. The potential and difficulties of using DAS for these objectives were studied using two DAS arrays. One at Garner Valley in Southern California (a 700-meter array adjacent to CA Highway 74) and another in Brady Hot Springs, Nevada (an 8700-meter array adjacent to Interstate 80). These studies experimentally evaluated the use of DAS data for monitoring traffic and assessing the use of traffic vibration as non-localized sources for seismic imaging. DAS arrays should also be resilient to issues with lighting conditions that are problematic for video monitoring and it may be sensitive to the weight of a vehicle. This study along a major interstate provides a basis for examining DAS' potential and limitations as a key component of intelligent highway systems.

  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. Focusing of Acoustic Waves through Acoustic Materials with Subwavelength Structures

    KAUST Repository

    Xiao, Bingmu

    2013-01-01

    -domain (FDTD) method for the two-dimensional acoustic wave equation. The theory provides the effective impedance and refractive index functions for the equivalent medium, which can reproduce the transmission and reflection spectral responses of the original

  12. Acoustic wave coupled magnetoelectric effect

    International Nuclear Information System (INIS)

    Gao, J.S.; Zhang, N.

    2016-01-01

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

  13. 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.

  14. 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...

  15. 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.

  16. Method and apparatus for generating acoustic waves

    International Nuclear Information System (INIS)

    Rao, G.V.; Gopal, R.

    1982-01-01

    A portable source of acoustic waves comprises a sample of iron-nickel alloy including an austenite phase cooled to become martensite, and a wave guide to transmit the acoustic waves. The source is applied to the pressure boundary region of a pressurized water reactor to simulate an actual metal flaw and test the calibration of the monitoring and surveillance system. With at most 29.7% nickel in the sample, the source provides acoustic emission due to ductile deformation, and with at least 30% nickel the acoustic emission is characteristic of a brittle deformation. Thus, the monitoring and surveillance system can be tested in either or both situations. In the prior art, synthetic waveform signals were used for such calibration but found not suitable for on-line simulation of the surveillance system. This invention provides an improved system in that it generates true acoustic signals. (author)

  17. 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.

  18. 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.

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

    KAUST Repository

    Xiao, Bingmu

    2013-05-01

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

  20. 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

  1. Injection locking of optomechanical oscillators via acoustic waves

    Science.gov (United States)

    Huang, Ke; Hossein-Zadeh, Mani

    2018-04-01

    Injection locking is a powerful technique for synchronization of oscillator networks and controlling the phase and frequency of individual oscillators using similar or other types of oscillators. Here, we present the first demonstration of injection locking of a radiation-pressure driven optomechanical oscillator (OMO) via acoustic waves. As opposed to previously reported techniques (based on pump modulation or direct application of a modulated electrostatic force), injection locking of OMO via acoustic waves does not require optical power modulation or physical contact with the OMO and it can easily be implemented on various platforms. Using this approach we have locked the phase and frequency of two distinct modes of a microtoroidal silica OMO to a piezoelectric transducer (PZT). We have characterized the behavior of the injection locked OMO with three acoustic excitation configurations and showed that even without proper acoustic impedance matching the OMO can be locked to the PZT and tuned over 17 kHz with only -30 dBm of RF power fed to the PZT. The high efficiency, simplicity and scalability of the proposed approach paves the road toward a new class of photonic systems that rely on synchronization of several OMOs to a single or multiple RF oscillators with applications in optical communication, metrology and sensing. Beyond its practical applications, injection locking via acoustic waves can be used in fundamental studies in quantum optomechanics where thermal and optical isolation of the OMO are critical.

  2. Acoustic metasurface for refracted wave manipulation

    Science.gov (United States)

    Han, Li-Xiang; Yao, Yuan-Wei; Zhang, Xin; Wu, Fu-Gen; Dong, Hua-Feng; Mu, Zhong-Fei; Li, Jing-bo

    2018-02-01

    Here we present a design of a transmitted acoustic metasurface based on a single row of Helmholtz resonators with varying geometric parameters. The proposed metasurface can not only steer an acoustic beam as expected from the generalized Snell's law of refraction, but also exhibits various interesting properties and potential applications such as insulation of two quasi-intersecting transmitted sound waves, ultrasonic Bessel beam generator, frequency broadening effect of anomalous refraction and focusing.

  3. 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.

  4. 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.

  5. Wave chaos in acoustics and elasticity

    International Nuclear Information System (INIS)

    Tanner, Gregor; Soendergaard, Niels

    2007-01-01

    Interpreting wave phenomena in terms of an underlying ray dynamics adds a new dimension to the analysis of linear wave equations. Forming explicit connections between spectra and wavefunctions on the one hand and the properties of a related ray dynamics on the other hand is a comparatively new research area, especially in elasticity and acoustics. The theory has indeed been developed primarily in a quantum context; it is increasingly becoming clear, however, that important applications lie in the field of mechanical vibrations and acoustics. We provide an overview over basic concepts in this emerging field of wave chaos. This ranges from ray approximations of the Green function to periodic orbit trace formulae and random matrix theory and summarizes the state of the art in applying these ideas in acoustics-both experimentally and from a theoretical/numerical point of view. (topical review)

  6. 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.

  7. Acoustic waves in unbounded shear flows

    International Nuclear Information System (INIS)

    Chagelishvili, G.D.; Khujadze, G.R.; Lominadze, J.G.; Rogava, A.D.

    1996-05-01

    The linear evolution of acoustic waves in fluid flow with constant density and uniform shear of velocity is investigated. The process of the mean flow energy extraction by the three-dimensional acoustic waves which is due to the non-normality of linear dynamics in shear flows is analyzed. The thorough examination of the dynamics of different physical quantities, specifying the wave evolution, is outlined. The revealing of the behaviour becomes possible owing to the nonmodal approach that has been extensively used in the study of the perturbations evolution in shear flows since the beginning of the nineties. In addition, a detailed analyses of the physics of shear energy gain by vortex and acoustic perturbations is presented. (author). 28 refs, 7 figs

  8. Distributed acoustic sensing for pipeline monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hill, David; McEwen-King, Magnus [OptaSense, QinetiQ Ltd., London (United Kingdom)

    2009-07-01

    Optical fibre is deployed widely across the oil and gas industry. As well as being deployed regularly to provide high bandwidth telecommunications and infrastructure for SCADA it is increasingly being used to sense pressure, temperature and strain along buried pipelines, on subsea pipelines and downhole. In this paper we present results from the latest sensing capability using standard optical fibre to detect acoustic signals along the entire length of a pipeline. In Distributed Acoustic Sensing (DAS) an optical fibre is used for both sensing and telemetry. In this paper we present results from the OptaSense{sup TM} system which has been used to detect third party intervention (TPI) along buried pipelines. In a typical deployment the system is connected to an existing standard single-mode fibre, up to 50km in length, and was used to independently listen to the acoustic / seismic activity at every 10 meter interval. We will show that through the use of advanced array processing of the independent, simultaneously sampled channels it is possible to detect and locate activity within the vicinity of the pipeline and through sophisticated acoustic signal processing to obtain the acoustic signature to classify the type of activity. By combining spare fibre capacity in existing buried fibre optic cables; processing and display techniques commonly found in sonar; and state-of-the-art in fibre-optic distributed acoustic sensing, we will describe the new monitoring capabilities that are available to the pipeline operator. Without the expense of retrofitting sensors to the pipeline, this technology can provide a high performance, rapidly deployable and cost effective method of providing gapless and persistent monitoring of a pipeline. We will show how this approach can be used to detect, classify and locate activity such as; third party interference (including activity indicative of illegal hot tapping); real time tracking of pigs; and leak detection. We will also show how an

  9. Nonlinear modulation of ion acoustic waves in a magnetized plasma

    International Nuclear Information System (INIS)

    Bharuthram, R.; Shukla, P.K.

    1987-01-01

    The quasistatic plasma slow response to coherent ion acoustic waves in a magnetized plasma is considered. A multidimensional cubic nonlinear Schroedinger equation is derived. It is found that the ion acoustic waves remain modulationally stable against oblique perturbations

  10. High-temperature bulk acoustic wave sensors

    International Nuclear Information System (INIS)

    Fritze, Holger

    2011-01-01

    Piezoelectric crystals like langasite (La 3 Ga 5 SiO 14 , LGS) and gallium orthophosphate (GaPO 4 ) exhibit piezoelectrically excited bulk acoustic waves at temperatures of up to at least 1450 °C and 900 °C, respectively. Consequently, resonant sensors based on those materials enable new sensing approaches. Thereby, resonant high-temperature microbalances are of particular interest. They correlate very small mass changes during film deposition onto resonators or gas composition-dependent stoichiometry changes of thin films already deposited onto the resonators with the resonance frequency shift of such devices. Consequently, the objective of the work is to review the high-temperature properties, the operation limits and the measurement principles of such resonators. The electromechanical properties of high-temperature bulk acoustic wave resonators such as mechanical stiffness, piezoelectric and dielectric constant, effective viscosity and electrical conductivity are described using a one-dimensional physical model and determined accurately up to temperatures as close as possible to their ultimate limit. Insights from defect chemical models are correlated with the electromechanical properties of the resonators. Thereby, crucial properties for stable operation as a sensor under harsh conditions are identified to be the formation of oxygen vacancies and the bulk conductivity. Operation limits concerning temperature, oxygen partial pressure and water vapor pressure are given. Further, application-relevant aspects such as temperature coefficients, temperature compensation and mass sensitivity are evaluated. In addition, approximations are introduced which make the exact model handy for routine data evaluation. An equivalent electrical circuit for high-temperature resonator devices is derived based on the one-dimensional physical model. Low- and high-temperature approximations are introduced. Thereby, the structure of the equivalent circuit corresponds to the

  11. High-temperature bulk acoustic wave sensors

    Science.gov (United States)

    Fritze, Holger

    2011-01-01

    Piezoelectric crystals like langasite (La3Ga5SiO14, LGS) and gallium orthophosphate (GaPO4) exhibit piezoelectrically excited bulk acoustic waves at temperatures of up to at least 1450 °C and 900 °C, respectively. Consequently, resonant sensors based on those materials enable new sensing approaches. Thereby, resonant high-temperature microbalances are of particular interest. They correlate very small mass changes during film deposition onto resonators or gas composition-dependent stoichiometry changes of thin films already deposited onto the resonators with the resonance frequency shift of such devices. Consequently, the objective of the work is to review the high-temperature properties, the operation limits and the measurement principles of such resonators. The electromechanical properties of high-temperature bulk acoustic wave resonators such as mechanical stiffness, piezoelectric and dielectric constant, effective viscosity and electrical conductivity are described using a one-dimensional physical model and determined accurately up to temperatures as close as possible to their ultimate limit. Insights from defect chemical models are correlated with the electromechanical properties of the resonators. Thereby, crucial properties for stable operation as a sensor under harsh conditions are identified to be the formation of oxygen vacancies and the bulk conductivity. Operation limits concerning temperature, oxygen partial pressure and water vapor pressure are given. Further, application-relevant aspects such as temperature coefficients, temperature compensation and mass sensitivity are evaluated. In addition, approximations are introduced which make the exact model handy for routine data evaluation. An equivalent electrical circuit for high-temperature resonator devices is derived based on the one-dimensional physical model. Low- and high-temperature approximations are introduced. Thereby, the structure of the equivalent circuit corresponds to the Butterworth

  12. Acoustic slow waves and the consolidation transition

    International Nuclear Information System (INIS)

    Johnson, D.L.; Plona, T.J.

    1982-01-01

    We have investigated the ultrasonic properties of unconsolidated (loose) glass beads and of lightly fused (consolidated) glass beads when the pore space is saturated with water. At a frequency of 500 kHz we have observed a single compressional wave in the former whose speed is 1.79 km/s and two distinct compressional waves with speeds 2.81 km/s and 0.96 km/s in the latter. The Biot theory is shown to give an accurate description of this phenomenon. We also analyze the acoustics of low temperature He ii in packed powder superleaks; either the fast wave for unconsolidated systems or the slow wave in a highly consolidated (fused) frame may be considered to be the 4th sound mode. In all such systems, the acoustic properties can be very simply understood by considering the velocities of propagation as continuous functions of the elastic moduli of the solid skeletal frames

  13. 25 years of dust acoustic waves

    Science.gov (United States)

    Merlino, Robert L.; Merlino

    2014-12-01

    The dust acoustic wave (DAW) was first discussed by P. K. Shukla in May of 1989 at the First Capri Workshop on Dusty Plasmas. In the past 25 years, the subsequent publication of the linear and nonlinear properties of the DAW (Rao, N. N., Shukla, P. K. and Yu, M. Y. 1990 Planet. Space Sci. 38, 543) has generated and sustained a large body of theoretical and experimental research that has clarified the physics of collective effects in dusty plasmas. A unique feature of the DAW is that it can be observed (literally) using laser illumination and high-speed videography, revealing details of wave-particle interactions at an unprecedented single particle level. This paper attempts to review some of the contributions and extensions of dust acoustic wave physics, as well as identify recent findings that illustrate the potential importance of this dust wave in the agglomeration of dust particles.

  14. 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

  15. Geological formation characterisation by acoustic waves

    International Nuclear Information System (INIS)

    Mari, J.L.; Gaudiani, P.; Delay, J.

    2010-01-01

    Document available in extended abstract form only. For many years, the transmission of a sonic wave through formations has been used for drilling measurements. The tools used are of monopole or dipole type. Monopole-type tools are the most commonly used. Sources and receivers are multidirectional. In the fluid, sources generate a compression wave which creates in the formation a compression wave (P wave) and a shear wave (S wave) at the refraction limit angles. In a vertical well, such tools permit the recording of five propagation modes: the refracted compression wave, the refracted shear wave (only in fast formations), the fluid wave, two dispersive guided modes which are the pseudo Rayleigh waves (only in fast formations) and the Stoneley waves. Full waveform acoustic measurements are represented as constant-offset sections or as common source point gathers, similar to those used in seismic operations. For the different modes, the acoustic parameters which are usually measured are: picked time, amplitude and frequency. The acoustic parameters allow one to determine the propagation velocities of the various modes and some petro-physical parameters and to obtain lithologic and mechanical information if the shear velocity of the formation has been measured. Usually the picking of the refracted S wave is difficult due to the interferences of different wave trains such as leaky modes associated with the refracted P waves and the pseudo Rayleigh. To compute a continuous log of shear velocity, we propose an hybrid method based on the local measurement of the shear velocity (picking of the arrival time of the refracted S wave) and on the analysis of the dispersion curve of the Stoneley modes ( Biot 1956, White 1965). We also show the benefit of using a shape index parameter named Ic, computed from the amplitudes (A1, A2 and A3) of the first refracted P wave to detect acoustic anomalies specially in fractured formation. The Ic parameter is independent of the energy of

  16. 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.

  17. 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.

  18. 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.

  19. Acoustic waves in granular materials

    NARCIS (Netherlands)

    Mouraille, O.J.P.; Luding, Stefan

    2008-01-01

    Dynamic simulations with discrete elements are used to obtain more insight into the wave propagation in dense granular media. A small perturbation is created on one side of a dense, static packing and examined during its propagation until it arrives at the opposite side. The influence of

  20. Surface Acoustic Waves in ferroelectrics

    Czech Academy of Sciences Publication Activity Database

    Tarasenko A., Nataliya; Jastrabík, Lubomír; Tarasenko, Alexander

    2004-01-01

    Roč. 298, - (2004), s. 325-333 ISSN 0015-0193 R&D Projects: GA AV ČR IBS1010203 Keywords : Rayleigh waves * ferroelectric films * phase transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.517, year: 2004

  1. Non-ideal dust acoustic waves

    International Nuclear Information System (INIS)

    Konefka, F; Contreras, J P; Puerta, J; Castro, E; MartIn, P

    2008-01-01

    The dispersion relation for dust acoustic waves (DA waves) functionally depends on the state equation for the charged dust grains. The ideal gas equation is usually used for studying the effect of temperature on this dispersion relation. However, since the space occupied by the grains can be important in high-density plasmas, the non-ideal effects can be important in this case. This paper analyses the dispersion relation for DA waves, when more precise state equations are used as those described for Pade approximants. The correction to the usual wave equation has been determined and the break point in density, where the ideal gas-state equation has been found. The non-ideal effects are more important for short wavelength ones, and the limits where those effects become important are also studied. Since there are several experimental results for these kinds of waves, the importance of the non-ideal effects in these cases is analysed in detail.

  2. Dual output acoustic wave sensor for molecular identification

    International Nuclear Information System (INIS)

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

    1991-01-01

    This patent describes an apparatus for detecting and identifying at least one unknown chemical species. It comprises: an acoustic wave device capable of generating, transmitting and receiving an acoustic wave, means for measuring the velocity of an acoustic wave travelling through the material; means for simultaneously measuring the attenuation of the acoustic wave traveling through the coating material; sampling means to contact the acoustic wave device to the unknown chemical species; means for determining the changes in both the attenuation and velocity values of the acoustic wave upon sorption of the unknown chemical species into the coating material; and means for correlating the magnitudes of the changes of velocity with respect to the changes of the attenuations of the acoustic wave; and means for comparing the values of the velocity and attenuation changes to known values of velocity and attenuation of known chemical species in order to identify the unknown sorbed chemical species

  3. Study of Ion Acoustic Wave Damping through Green's Functions

    DEFF Research Database (Denmark)

    Hsuan, H.C.S.; Jensen, Vagn Orla

    1973-01-01

    Green's function analyses of ion acoustic waves in streaming plasmas show that, in general, the waves damp algebraically rather than exponentially with distance from exciter.......Green's function analyses of ion acoustic waves in streaming plasmas show that, in general, the waves damp algebraically rather than exponentially with distance from exciter....

  4. 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.

  5. Injection locking of optomechanical oscillators via acoustic waves.

    Science.gov (United States)

    Huang, Ke; Hossein-Zadeh, Mani

    2018-04-02

    Injection locking is an effective technique for synchronization of oscillator networks and controlling the phase and frequency of individual oscillators. As such, exploring new mechanisms for injection locking of emerging oscillators is important for their usage in various systems. Here, we present the first demonstration of injection locking of a radiation pressure driven optomechanical oscillator (OMO) via acoustic waves. As opposed to previously reported techniques (based on pump modulation or direct application of a modulated electrostatic force), injection locking of OMO via acoustic waves does not require optical power modulation or physical contact with the OMO and it can be easily implemented on various platforms to lock different types of OMOs independent of their size and structure. Using this approach we have locked the phase and frequency of two distinct modes of a microtoroidal silica OMO to a piezoelectric transducer (PZT). We have characterized the behavior of the injection locked OMO with three acoustic excitation configurations and showed that even without proper acoustic impedance, matching the OMO can be locked to the PZT and tuned over 17 kHz with only -30 dBm of RF power fed to the PZT. The high efficiency, simplicity, and scalability of the proposed approach paves the road toward a new class of photonic systems that rely on synchronization of several OMOs to a single or multiple RF oscillators with applications in optical communication, metrology, and sensing. Beyond its practical applications, injection locking via acoustic waves can be used in fundamental studies in quantum optomechanics where thermal and optical isolation of the OMO are critical.

  6. Support minimized inversion of acoustic and elastic wave scattering

    International Nuclear Information System (INIS)

    Safaeinili, A.

    1994-01-01

    This report discusses the following topics on support minimized inversion of acoustic and elastic wave scattering: Minimum support inversion; forward modelling of elastodynamic wave scattering; minimum support linearized acoustic inversion; support minimized nonlinear acoustic inversion without absolute phase; and support minimized nonlinear elastic inversion

  7. Acoustic waves in polydispersed bubbly liquids

    International Nuclear Information System (INIS)

    Gubaidullin, D A; Gubaidullina, D D; Fedorov, Yu V

    2014-01-01

    The propagation of acoustic waves in polydispersed mixtures of liquid with two sorts of gas bubbles each of which has its own bubble size distribution function is studied. The system of the differential equations of the perturbed motion of a mixture is presented, the dispersion relation is obtained. Equilibrium speed of sound, low-frequency and high-frequency asymptotes of the attenuation coefficient are found. Comparison of the developed theory with known experimental data is presented

  8. Acoustic waves in polydispersed bubbly liquids

    Science.gov (United States)

    Gubaidullin, D. A.; Gubaidullina, D. D.; Fedorov, Yu V.

    2014-11-01

    The propagation of acoustic waves in polydispersed mixtures of liquid with two sorts of gas bubbles each of which has its own bubble size distribution function is studied. The system of the differential equations of the perturbed motion of a mixture is presented, the dispersion relation is obtained. Equilibrium speed of sound, low-frequency and high-frequency asymptotes of the attenuation coefficient are found. Comparison of the developed theory with known experimental data is presented.

  9. Angular momentum transport by tidal acoustic wave

    International Nuclear Information System (INIS)

    Sakurai, T.

    1976-01-01

    An analytical expression of the braking torque on a Jacobian ellipsoid rotating steadily in an enviromental gas is given, based on the assumption that the ellipsoid rotates around its shortest principal axis with an angular momentum slightly larger than that at the bifurcation point of the Maclaurin spheroid. This braking torque is effected by the gravitational interaction between the ellipsoid matter and a spiral density configuration in the environmental gas. This spiral configuration which is called a tidal acoustic wave, is caused by the zone of silence effect in a supersonic flow. With respect to a coordinates system rotating with the ellipsoid, a supersonic region appears outside a certain radius. In this supersonic region, the effect of the non-axisymmetric fluctuation in the ellipsoid potential propagates along the downstream branches of the Mach waves. This one-sided response of the supersonic part causes the tidal acoustic wave. The discussion is restricted to the equatorial plane, and an acoustic approximation of the basic equations is used under the assumption that the self-gravity effect of the environmental gas is negligable in comparison to the main gravity of the ellipsoid. The results are applied to the pre- and post-Main sequence phases of a rotating star, and relating astrophysical problems are discussed. (Auth.)

  10. Angular momentum transport by tidal acoustic wave

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, T [Kyoto Univ. (Japan). Faculty of Engineering

    1976-05-01

    An analytical expression of the braking torque on a Jacobian ellipsoid rotating steadily in an enviromental gas is given, based on the assumption that the ellipsoid rotates around its shortest principal axis with an angular momentum slightly larger than that at the bifurcation point of the Maclaurin spheroid. This braking torque is effected by the gravitational interaction between the ellipsoid matter and a spiral density configuration in the environmental gas. This spiral configuration which is called a tidal acoustic wave, is caused by the zone of silence effect in a supersonic flow. With respect to a coordinates system rotating with the ellipsoid, a supersonic region appears outside a certain radius. In this supersonic region, the effect of the non-axisymmetric fluctuation in the ellipsoid potential propagates along the downstream branches of the Mach waves. This one-sided response of the supersonic part causes the tidal acoustic wave. The discussion is restricted to the equatorial plane, and an acoustic approximation of the basic equations is used under the assumption that the self-gravity effect of the environmental gas is negligable in comparison to the main gravity of the ellipsoid. The results are applied to the pre- and post-Main sequence phases of a rotating star, and relating astrophysical problems are discussed.

  11. Non-Linear Excitation of Ion Acoustic Waves

    DEFF Research Database (Denmark)

    Michelsen, Poul; Hirsfield, J. L.

    1974-01-01

    The excitation of ion acoustic waves by nonlinear coupling of two transverse magnetic waves generated in a microwave cavity was investigated. Measurements of the wave amplitude showed good agreement with calculations based on the Vlasov equation.......The excitation of ion acoustic waves by nonlinear coupling of two transverse magnetic waves generated in a microwave cavity was investigated. Measurements of the wave amplitude showed good agreement with calculations based on the Vlasov equation....

  12. 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.

  13. Acoustic evaluation of wood quality in standing trees. Part I, Acoustic wave behavior

    Science.gov (United States)

    Xiping Wang; Robert J. Ross; Peter Carter

    2007-01-01

    Acoustic wave velocities in standing trees or live softwood species were measured by the time-of-flight (TOF) method. Tree velocities were compared with acoustic velocities measured in corresponding butt logs through a resonance acoustic method. The experimental data showed a skewed relationship between tree and log acoustic measurements. For most trees tested,...

  14. 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.

  15. Electron Acoustic Waves in Pure Ion Plasmas

    Science.gov (United States)

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

    2009-11-01

    Electron Acoustic Waves (EAW) are the low frequency branch of electrostatic plasma waves. These waves exist in neutralized plasmas, pure electron plasmas and in pure ion plasmasfootnotetextF. Anderegg et al., PRL 102, 095001 (2009) and PoP 16, 055705 (2009). (where the name is deceptive). Here, we observe standing mθ= 0 mz= 1 EAWs in a pure ion plasma column. At small amplitude, the EAWs have a phase velocity vph ˜1.4 v, and the frequencies are in close agreement with theory. At moderate amplitudes, waves can be excited over a broad range of frequencies, with observed phase velocities in the range of 1.4 v vph diagnostic shows that particles slower than vph oscillate in phase with the wave, while particles moving faster than vph oscillate 180^o out of phase with the wave. From a fluid perspective, this gives an unusual negative dynamical compressibility. That is, the wave pressure oscillations are 180^o out of phase from the density oscillations, almost fully canceling the electrostatic restoring force, giving the low and malleable frequency.

  16. Twisted electron-acoustic waves in plasmas

    International Nuclear Information System (INIS)

    Aman-ur-Rehman; Ali, S.; Khan, S. A.; Shahzad, K.

    2016-01-01

    In the paraxial limit, a twisted electron-acoustic (EA) wave is studied in a collisionless unmagnetized plasma, whose constituents are the dynamical cold electrons and Boltzmannian hot electrons in the background of static positive ions. The analytical and numerical solutions of the plasma kinetic equation suggest that EA waves with finite amount of orbital angular momentum exhibit a twist in its behavior. The twisted wave particle resonance is also taken into consideration that has been appeared through the effective wave number q_e_f_f accounting for Laguerre-Gaussian mode profiles attributed to helical phase structures. Consequently, the dispersion relation and the damping rate of the EA waves are significantly modified with the twisted parameter η, and for η → ∞, the results coincide with the straight propagating plane EA waves. Numerically, new features of twisted EA waves are identified by considering various regimes of wavelength and the results might be useful for transport and trapping of plasma particles in a two-electron component plasma.

  17. Plasmon band gap generated by intense ion acoustic waves

    International Nuclear Information System (INIS)

    Son, S.; Ku, S.

    2010-01-01

    In the presence of an intense ion acoustic wave, the energy-momentum dispersion relation of plasmons is strongly modified to exhibit a band gap structure. The intensity of an ion acoustic wave might be measured from the band gap width. The plasmon band gap can be used to block the nonlinear cascading channel of the Langmuir wave decay.

  18. Interaction of externally-driven acoustic waves with compressible convection

    International Nuclear Information System (INIS)

    Jones, P.; Merryfield, W.

    1992-01-01

    Two-dimensional numerical simulations are used to examine the interaction of acoustic waves with a compressible convecting fluid. Acoustic waves are forced at the lower boundary of the computational domain and propagate through a three-layer system undergoing vigorous penetrative convection. Energy exchange between the wave and the fluid is analyzed using a work integral formulation

  19. 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.

  20. Ultrasound acoustic wave energy transfer and harvesting

    Science.gov (United States)

    Shahab, Shima; Leadenham, Stephen; Guillot, François; Sabra, Karim; Erturk, Alper

    2014-04-01

    This paper investigates low-power electricity generation from ultrasound acoustic wave energy transfer combined with piezoelectric energy harvesting for wireless applications ranging from medical implants to naval sensor systems. The focus is placed on an underwater system that consists of a pulsating source for spherical wave generation and a harvester connected to an external resistive load for quantifying the electrical power output. An analytical electro-acoustic model is developed to relate the source strength to the electrical power output of the harvester located at a specific distance from the source. The model couples the energy harvester dynamics (piezoelectric device and electrical load) with the source strength through the acoustic-structure interaction at the harvester-fluid interface. Case studies are given for a detailed understanding of the coupled system dynamics under various conditions. Specifically the relationship between the electrical power output and system parameters, such as the distance of the harvester from the source, dimensions of the harvester, level of source strength, and electrical load resistance are explored. Sensitivity of the electrical power output to the excitation frequency in the neighborhood of the harvester's underwater resonance frequency is also reported.

  1. Acoustic wave transmission through piezoelectric structured materials.

    Science.gov (United States)

    Lam, M; Le Clézio, E; Amorín, H; Algueró, M; Holc, Janez; Kosec, Marija; Hladky-Hennion, A C; Feuillard, G

    2009-05-01

    This paper deals with the transmission of acoustic waves through multilayered piezoelectric materials. It is modeled in an octet formalism via the hybrid matrix of the structure. The theoretical evolution with the angle and frequency of the transmission coefficients of ultrasonic plane waves propagating through a partially depoled PZT plate is compared to finite element calculations showing that both methods are in very good agreement. The model is then used to study a periodic stack of 0.65 PMN-0.35 PT/0.90 PMN-0.10 PT layers. The transmission spectra are interpreted in terms of a dispersive behavior of the critical angles of longitudinal and transverse waves, and band gap structures are analysed. Transmission measurements confirm the theoretical calculations and deliver an experimental validation of the model.

  2. 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

  3. Evanescent Acoustic Wave Scattering by Targets and Diffraction by Ripples Graduate Traineeship Award in Ocean Acoustics

    National Research Council Canada - National Science Library

    Osterhoudt, Curtis F; Marston, Philip L

    2007-01-01

    .... The purpose of his research was to improve the understanding of the way that acoustic evanescent waves interact with targets buried in sediments in situations encountered in underwater acoustics...

  4. 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.

  5. Simulation of dust-acoustic waves

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  6. 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

  7. Acoustical sensing of cardiomyocyte cluster beating

    Energy Technology Data Exchange (ETDEWEB)

    Tymchenko, Nina; Kunze, Angelika [Dept. of Applied Physics, Chalmers University of Technology, 412 96 Göteborg (Sweden); Dahlenborg, Kerstin [Cellectis, 413 46 Göteborg (Sweden); Svedhem, Sofia, E-mail: sofia.svedhem@chalmers.se [Dept. of Applied Physics, Chalmers University of Technology, 412 96 Göteborg (Sweden); Steel, Daniella [Cellectis, 413 46 Göteborg (Sweden)

    2013-06-14

    Highlights: •An example of the application of QCM-D to live cell studies. •Detection of human pluripotent stem cell-derived cardiomyocyte cluster beating. •Clusters were studied in a thin liquid film and in a large liquid volume. •The QCM-D beating profile provides an individual fingerprint of the hPS-CMCs. -- Abstract: Spontaneously beating human pluripotent stem cell-derived cardiomyocytes clusters (CMCs) represent an excellent in vitro tool for studies of human cardiomyocyte function and for pharmacological cardiac safety assessment. Such testing typically requires highly trained operators, precision plating, or large cell quantities, and there is a demand for real-time, label-free monitoring of small cell quantities, especially rare cells and tissue-like structures. Array formats based on sensing of electrical or optical properties of cells are being developed and in use by the pharmaceutical industry. A potential alternative to these techniques is represented by the quartz crystal microbalance with dissipation monitoring (QCM-D) technique, which is an acoustic surface sensitive technique that measures changes in mass and viscoelastic properties close to the sensor surface (from nm to μm). There is an increasing number of studies where QCM-D has successfully been applied to monitor properties of cells and cellular processes. In the present study, we show that spontaneous beating of CMCs on QCM-D sensors can be clearly detected, both in the frequency and the dissipation signals. Beating rates in the range of 66–168 bpm for CMCs were detected and confirmed by simultaneous light microscopy. The QCM-D beating profile was found to provide individual fingerprints of the hPS-CMCs. The presented results point towards acoustical assays for evaluation cardiotoxicity.

  8. Electron Acoustic Waves in Pure Ion Plasmas

    Science.gov (United States)

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

    2012-10-01

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

  9. Proposed frustrated-total-reflection acoustic sensing method

    International Nuclear Information System (INIS)

    Hull, J.R.

    1981-01-01

    Modulation of electromagnetic energy transmission through a frustrated-total-reflection device by pressure-induced changes in the index of refraction is proposed for use as an acoustic detector. Maximum sensitivity occurs for angles of incidence near the critical angle. The minimum detectable pressure in air is limited by Brownian noise. Acoustic propagation losses and diffraction of the optical beam by the acoustic signal limit the minimum acoustic wavelength to lengths of the order of the spatial extent of the optical beam. The response time of the method is fast enough to follow individual acoustic waves

  10. Multi reflection of Lamb wave emission in an acoustic waveguide sensor.

    Science.gov (United States)

    Schmitt, Martin; Olfert, Sergei; Rautenberg, Jens; Lindner, Gerhard; Henning, Bernd; Reindl, Leonhard Michael

    2013-02-27

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

  11. Acoustic remote sensing of ocean flows

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desa, E.

    Acoustic techniques have become powerful tools for measurement of ocean circulation mainly because of the ability of acoustic signals to travel long distances in water, and the inherently non-invasive nature of measurement. The satellite remote...

  12. International Symposium on Acoustic Remote Sensing of the Atmosphere and Oceans (2nd).

    Science.gov (United States)

    1983-09-26

    work to develop a model the volume wave to form the boundary which relates hydrodynamical features of 6 ~A the ocean-air interface to ambient noise...is my belief oscillating bubbles, splashing waves and that the sodar work is not well known in water droplets, bubble cavitation , the Navy acoustics...Temperature," in accumulate in the same locations. Major Proceedings, InternationaZ Symposi- pollutants include oil spills, drilling w on Remote Sensing of

  13. Multispectral Analysis of Surface Wave (MASW) Analysis of Near-Surface Structure at Brady Hot Springs from Active Source and Ambient Noise Using a 8700-meter Distributed Acoustic Sensing (DAS) Array

    Science.gov (United States)

    Wang, H. F.; Lord, N. E.; Zeng, X.; Fratta, D.; Feigl, K. L.; Team, P.

    2016-12-01

    The Porotomo research team deployed 8700-meters of Distributed Acoustic Sensing (DAS) cable in a shallow trench on the surface and 400 meters down a borehole at Brady Hot Springs, Nevada in March 2016. The goal of the experiment was to detect changes in geophysical properties associated with hydrologic changes. The DAS cable occupied a natural laboratory of 1500-by-500-by-400-meters overlying a commercial, geothermal field operated by Ormat Technologies. The DAS cable was laid out in three parallel zig-zag lines with line segments approximately 120-meters in length. A large Vibroseis truck (T-Rex) provided the seismic source with a sweep frequency between 5 and 80 Hz over 20 seconds. Over the 15 days of the experiment, the Vibroseis truck re-occupied approximately 250 locations outside and within the array days while changes were made in water reinjection from the power plant into wells in the field. At each source location, one vertical and two orthogonal horizontal modes were excited. Dispersion curves were constructed using MASW and a Vibroseis source location approximately in line with each DAS cable segment or from ambient noise correlation functions. Representative fence diagrams of S-wave profiles were constructed by inverting the dispersion curves obtained for several different line segments.

  14. Experiments on stress dependent borehole acoustic waves.

    Science.gov (United States)

    Hsu, Chaur-Jian; Kane, Michael R; Winkler, Kenneth; Wang, Canyun; Johnson, David Linton

    2011-10-01

    In the laboratory setup, a borehole traverses a dry sandstone formation, which is subjected to a controlled uniaxial stress in the direction perpendicular to the borehole axis. Measurements are made in a single loading-unloading stress cycle from zero to 10 MPa and then back down to zero stress. The applied stress and the presence of the borehole induce anisotropy in the bulk of the material and stress concentration around the borehole, both azimuthally and radially. Acoustic waves are generated and detected in the water-filled borehole, including compressional and shear headwaves, as well as modes of monopole, dipole, quadrupole, and higher order azimuthal symmetries. The linear and non-linear elastic parameters of the formation material are independently quantified, and utilized in conjunction with elastic theories to predict the characteristics of various borehole waves at zero and finite stress conditions. For example, an analytic theory is developed which is successfully used to estimate the changes of monopole tube mode at low frequency resulted from uniaxial stress, utilizing the measured material third order elasticity parameters. Comparisons between various measurements as well as that between experiments and theories are also presented. © 2011 Acoustical Society of America

  15. Sensing small changes in a wave chaotic scattering system

    International Nuclear Information System (INIS)

    Taddese, Biniyam Tesfaye; Antonsen, Thomas M.; Ott, Edward; Anlage, Steven M.

    2010-01-01

    Classical analogs of the quantum mechanical concepts of the Loschmidt Echo and quantum fidelity are developed with the goal of detecting small perturbations in a closed wave chaotic region. Sensing techniques that employ a one-recording-channel time-reversal-mirror, which in turn relies on time reversal invariance and spatial reciprocity of the classical wave equation, are introduced. In analogy with quantum fidelity, we employ scattering fidelity techniques which work by comparing response signals of the scattering region, by means of cross correlation and mutual information of signals. The performance of the sensing techniques is compared for various perturbations induced experimentally in an acoustic resonant cavity. The acoustic signals are parametrically processed to mitigate the effect of dissipation and to vary the spatial diversity of the sensing schemes. In addition to static boundary condition perturbations at specified locations, perturbations to the medium of wave propagation are shown to be detectable, opening up various real world sensing applications in which a false negative cannot be tolerated.

  16. Influence of acoustic waves on TEA CO2 laser performance

    CSIR Research Space (South Africa)

    Von Bergmann, H

    2007-01-01

    Full Text Available In this paper the author’s present results on the influence of acoustic waves on the output laser beam from high repetition rate TEA CO2 lasers. The authors show that acoustic waves generated inside the cavity lead to deterioration in beam quality...

  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. 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.

  19. 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.

  20. Influence of the interaction of ions-dust grains on ion acoustic wave and dust acoustic wave

    International Nuclear Information System (INIS)

    Hua Jianjun; Liu Jinyuan; Ma Tengcai

    2004-01-01

    Based on a set of hydrodynamic equations and a linear time-dependent perturbation theory, the influence of the interaction of ions-dust grains on ion acoustic wave IAW and dust acoustic wave DAW in dusty plasma is analyzed. The results show that the interaction makes IAW more stable and DAW less stable

  1. 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

  2. Nonlinear self-modulation of ion-acoustic waves

    International Nuclear Information System (INIS)

    Ikezi, H.; Schwarzenegger, K.; Simons, A.L.; Ohsawa, Y.; Kamimura, T.

    1978-01-01

    The nonlinear evolution of an ion-acoustic wave packet is studied. Experimentally, it is found that (i) nonlinear phase modulation develops in the wave packet; (ii) the phase modulation, together with the dispersion effect, causes expansion and breaking of the wave packet; (iii) the ions trapped in the troughs of the wave potential introduce self-phase modulation; and (iv) the ion-acoustic wave is stable with respect to the modulational instability. Computer simulations have reproduced the experimental results. The physical picture and the model equation describing the wave evolution are discussed

  3. Ion-acoustic cnoidal waves in a quantum plasma

    International Nuclear Information System (INIS)

    Mahmood, S.; Haas, F.

    2014-01-01

    Nonlinear ion-acoustic cnoidal wave structures are studied in an unmagnetized quantum plasma. Using the reductive perturbation method, a Korteweg-de Vries equation is derived for appropriate boundary conditions and nonlinear periodic wave solutions are obtained. The corresponding analytical solution and numerical plots of the ion-acoustic cnoidal waves and solitons in the phase plane are presented using the Sagdeev pseudo-potential approach. The variations in the nonlinear potential of the ion-acoustic cnoidal waves are studied at different values of quantum parameter H e which is the ratio of electron plasmon energy to electron Fermi energy defined for degenerate electrons. It is found that both compressive and rarefactive ion-acoustic cnoidal wave structures are formed depending on the value of the quantum parameter. The dependence of the wavelength and frequency on nonlinear wave amplitude is also presented

  4. Effect of Forcing Function on Nonlinear Acoustic Standing Waves

    Science.gov (United States)

    Finkheiner, Joshua R.; Li, Xiao-Fan; Raman, Ganesh; Daniels, Chris; Steinetz, Bruce

    2003-01-01

    Nonlinear acoustic standing waves of high amplitude have been demonstrated by utilizing the effects of resonator shape to prevent the pressure waves from entering saturation. Experimentally, nonlinear acoustic standing waves have been generated by shaking an entire resonating cavity. While this promotes more efficient energy transfer than a piston-driven resonator, it also introduces complicated structural dynamics into the system. Experiments have shown that these dynamics result in resonator forcing functions comprised of a sum of several Fourier modes. However, previous numerical studies of the acoustics generated within the resonator assumed simple sinusoidal waves as the driving force. Using a previously developed numerical code, this paper demonstrates the effects of using a forcing function constructed with a series of harmonic sinusoidal waves on resonating cavities. From these results, a method will be demonstrated which allows the direct numerical analysis of experimentally generated nonlinear acoustic waves in resonators driven by harmonic forcing functions.

  5. 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 ).

  6. A Mobile Acoustic Subsurface Sensing (MASS) system for rapid roadway assessment.

    Science.gov (United States)

    Lu, Yifeng; Zhang, Yi; Cao, Yinghong; McDaniel, J Gregory; Wang, Ming L

    2013-05-08

    Surface waves are commonly used for vibration-based nondestructive testing for infrastructure. Spectral Analysis of Surface Waves (SASW) has been used to detect subsurface properties for geologic inspections. Recently, efforts were made to scale down these subsurface detection approaches to see how they perform on small-scale structures such as concrete slabs and pavements. Additional efforts have been made to replace the traditional surface-mounted transducers with non-contact acoustic transducers. Though some success has been achieved, most of these new approaches are inefficient because they require point-to-point measurements or off-line signal analysis. This article introduces a Mobile Acoustic Subsurface Sensing system as MASS, which is an improved surface wave based implementation for measuring the subsurface profile of roadways. The compact MASS system is a 3-wheeled cart outfitted with an electromagnetic impact source, distance register, non-contact acoustic sensors and data acquisition/ processing equipment. The key advantage of the MASS system is the capability to collect measurements continuously at walking speed in an automatic way. The fast scan and real-time analysis advantages are based upon the non-contact acoustic sensing and fast air-coupled surface wave analysis program. This integration of hardware and software makes the MASS system an efficient mobile prototype for the field test.

  7. A Mobile Acoustic Subsurface Sensing (MASS System for Rapid Roadway Assessment

    Directory of Open Access Journals (Sweden)

    Ming L. Wang

    2013-05-01

    Full Text Available Surface waves are commonly used for vibration-based nondestructive testing for infrastructure. Spectral Analysis of Surface Waves (SASW has been used to detect subsurface properties for geologic inspections. Recently, efforts were made to scale down these subsurface detection approaches to see how they perform on small-scale structures such as concrete slabs and pavements. Additional efforts have been made to replace the traditional surface-mounted transducers with non-contact acoustic transducers. Though some success has been achieved, most of these new approaches are inefficient because they require point-to-point measurements or off-line signal analysis. This article introduces a Mobile Acoustic Subsurface Sensing system as MASS, which is an improved surface wave based implementation for measuring the subsurface profile of roadways. The compact MASS system is a 3-wheeled cart outfitted with an electromagnetic impact source, distance register, non-contact acoustic sensors and data acquisition/ processing equipment. The key advantage of the MASS system is the capability to collect measurements continuously at walking speed in an automatic way. The fast scan and real-time analysis advantages are based upon the non-contact acoustic sensing and fast air-coupled surface wave analysis program. This integration of hardware and software makes the MASS system an efficient mobile prototype for the field test.

  8. 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.

  9. 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.

  10. 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...

  11. Electro-acoustic solitary waves in dusty plasmas

    International Nuclear Information System (INIS)

    Mamun, A.A.; Sayed, F.

    2005-10-01

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

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

    Science.gov (United States)

    Levine, Richard C.

    1980-01-01

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

  13. Opportunities for shear energy scaling in bulk acoustic wave resonators

    NARCIS (Netherlands)

    Jose, Sumy; Hueting, Raymond Josephus Engelbart

    2014-01-01

    An important energy loss contribution in bulk acoustic wave resonators is formed by so-called shear waves, which are transversal waves that propagate vertically through the devices with a horizontal motion. In this work, we report for the first time scaling of the shear-confined spots, i.e., spots

  14. Nucleus-acoustic shock waves in white dwarfs

    Indian Academy of Sciences (India)

    S Jannat

    2018-03-09

    Mar 9, 2018 ... [17] of gravitational waves emitted by two merging black holes has opened up a new era of theoretical and observational research in astrophysics [17–19] which leads us to expect that in the near future a similar or dif- ferent kind of waves (like nucleus-acoustic (NA) waves. [20,21]) and associated nonlinear ...

  15. Dust acoustic solitary and shock waves in strongly coupled dusty ...

    Indian Academy of Sciences (India)

    between nonlinear and dispersion effects can result in the formation of symmetrical solitary waves. Also shock ... et al have studied the effect of nonadiabatic dust charge variation on the nonlinear dust acoustic wave with ..... Figure 5 presents the border between oscillatory- and monotonic-type shock waves as functions of ...

  16. Coded acoustic wave sensors and system using time diversity

    Science.gov (United States)

    Solie, Leland P. (Inventor); Hines, Jacqueline H. (Inventor)

    2012-01-01

    An apparatus and method for distinguishing between sensors that are to be wirelessly detected is provided. An interrogator device uses different, distinct time delays in the sensing signals when interrogating the sensors. The sensors are provided with different distinct pedestal delays. Sensors that have the same pedestal delay as the delay selected by the interrogator are detected by the interrogator whereas other sensors with different pedestal delays are not sensed. Multiple sensors with a given pedestal delay are provided with different codes so as to be distinguished from one another by the interrogator. The interrogator uses a signal that is transmitted to the sensor and returned by the sensor for combination and integration with the reference signal that has been processed by a function. The sensor may be a surface acoustic wave device having a differential impulse response with a power spectral density consisting of lobes. The power spectral density of the differential response is used to determine the value of the sensed parameter or parameters.

  17. Numerical simulation of single bubble dynamics under acoustic travelling waves.

    Science.gov (United States)

    Ma, Xiaojian; Huang, Biao; Li, Yikai; Chang, Qing; Qiu, Sicong; Su, Zheng; Fu, Xiaoying; Wang, Guoyu

    2018-04-01

    The objective of this paper is to apply CLSVOF method to investigate the single bubble dynamics in acoustic travelling waves. The Naiver-Stokes equation considering the acoustic radiation force is proposed and validated to capture the bubble behaviors. And the CLSVOF method, which can capture the continuous geometric properties and satisfies mass conservation, is applied in present work. Firstly, the regime map, depending on the dimensionless acoustic pressure amplitude and acoustic wave number, is constructed to present different bubble behaviors. Then, the time evolution of the bubble oscillation is investigated and analyzed. Finally, the effect of the direction and the damping coefficient of acoustic wave propagation on the bubble behavior are also considered. The numerical results show that the bubble presents distinct oscillation types in acoustic travelling waves, namely, volume oscillation, shape oscillation, and splitting oscillation. For the splitting oscillation, the formation of jet, splitting of bubble, and the rebound of sub-bubbles may lead to substantial increase in pressure fluctuations on the boundary. For the shape oscillation, the nodes and antinodes of the acoustic pressure wave contribute to the formation of the "cross shape" of the bubble. It should be noted that the direction of the bubble translation and bubble jet are always towards the direction of wave propagation. In addition, the damping coefficient causes bubble in shape oscillation to be of asymmetry in shape and inequality in size, and delays the splitting process. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Propagation of nonlinear ion acoustic wave with generation of long-wavelength waves

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu; Kamimura, Tetsuo

    1978-01-01

    The nonlinear propagation of the wave packet of an ion acoustic wave with wavenumber k 0 asymptotically equals k sub(De) (the electron Debye wavenumber) is investigated by computer simulations. From the wave packet of the ion acoustic wave, waves with long wavelengths are observed to be produced within a few periods for the amplitude oscillation of the original wave packet. These waves are generated in the region where the original wave packet exists. Their characteristic wavelength is of the order of the length of the wave packet, and their propagation velocity is almost equal to the ion acoustic speed. The long-wavelength waves thus produced strongly affect the nonlinear evolution of the original wave packet. (auth.)

  19. 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...

  20. 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...

  1. Experimental observation of azimuthal shock waves on nonlinear acoustical vortices

    International Nuclear Information System (INIS)

    Brunet, Thomas; Thomas, Jean-Louis; Marchiano, Regis; Coulouvrat, Francois

    2009-01-01

    Thanks to a new focused array of piezoelectric transducers, experimental results are reported here to evidence helical acoustical shock waves resulting from the nonlinear propagation of acoustical vortices (AVs). These shock waves have a three-dimensional spiral shape, from which both the longitudinal and azimuthal components are studied. The inverse filter technique used to synthesize AVs allows various parameters to be varied, especially the topological charge which is the key parameter describing screw dislocations. Firstly, an analysis of the longitudinal modes in the frequency domain reveals a wide cascade of harmonics (up to the 60th order) leading to the formation of the shock waves. Then, an original measurement in the transverse plane exhibits azimuthal behaviour which has never been observed until now for acoustical shock waves. Finally, these new experimental results suggest interesting potential applications of nonlinear effects in terms of acoustics spanners in order to manipulate small objects.

  2. 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.

  3. 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....

  4. Acoustic wave spread in superconducting-normal-superconducting sandwich

    International Nuclear Information System (INIS)

    Urushadze, G.I.

    2004-01-01

    The acoustic wave spread, perpendicular to the boundaries between superconducting and normal metals in superconducting-normal-superconducting (SNS) sandwich has been considered. The alternate current flow sound induced by the Green function method has been found and the coefficient of the acoustic wave transmission through the junction γ=(S 1 -S 2 )/S 1 , (where S 1 and S 2 are average energy flows formed on the first and second boundaries) as a function of the phase difference between superconductors has been investigated. It is shown that while the SNS sandwich is almost transparent for acoustic waves (γ 0 /τ), n=0,1,2, ... (where τ 0 /τ is the ratio of the broadening of the quasiparticle energy levels in impurity normal metal as a result of scattering of the carriers by impurities 1/τ to the spacing between energy levels 1/τ 0 ), γ=2, (S 2 =-S 1 ), which corresponds to the full reflection of the acoustic wave from SNS sandwich. This result is valid for the limit of a pure normal metal but in the main impurity case there are two amplification and reflection regions for acoustic waves. The result obtained shows promise for the SNS sandwich as an ideal mirror for acoustic wave reflection

  5. Three-dimensional stability of solitary kinetic Alfven waves and ion-acoustic waves

    International Nuclear Information System (INIS)

    Ghosh, G.; Das, K.P.

    1994-01-01

    Starting from a set of equations that lead to a linear dispersion relation coupling kinetic Alfven waves and ion-acoustic waves, three-dimensional KdV equations are derived for these waves. These equations are then used to investigate the three-dimensional stability of solitary kinetic Alfven waves and ion-acoustic waves by the small-k perturbation expansion method of Rowlands and Infeld. For kinetic Alfven waves it is found that there is instability if the direction of the plane-wave perturbation lies inside a cone, and the growth rate of the instability attains a maximum when the direction of the perturbation lies in the plane containing the external magnetic field and the direction of propagation of the solitary wave. For ion-acoustic waves the growth rate of instability attains a maximum when the direction of the perturbation lies in a plane perpendicular to the direction of propagation of the solitary wave. (Author)

  6. Capacitive acoustic wave detector and method of using same

    Science.gov (United States)

    Yost, William T. (Inventor)

    1994-01-01

    A capacitor having two substantially parallel conductive faces is acoustically coupled to a conductive sample end such that the sample face is one end of the capacitor. A non-contacting dielectric may serve as a spacer between the two conductive plates. The formed capacitor is connected to an LC oscillator circuit such as a Hartley oscillator circuit producing an output frequency which is a function of the capacitor spacing. This capacitance oscillates as the sample end coating is oscillated by an acoustic wave generated in the sample by a transmitting transducer. The electrical output can serve as an absolute indicator of acoustic wave displacement.

  7. 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.

  8. Nonlinear acoustic waves in micro-inhomogeneous solids

    CERN Document Server

    Nazarov, Veniamin

    2014-01-01

    Nonlinear Acoustic Waves in Micro-inhomogeneous Solids covers the broad and dynamic branch of nonlinear acoustics, presenting a wide variety of different phenomena from both experimental and theoretical perspectives. The introductory chapters, written in the style of graduate-level textbook, present a review of the main achievements of classic nonlinear acoustics of homogeneous media. This enables readers to gain insight into nonlinear wave processes in homogeneous and micro-inhomogeneous solids and compare it within the framework of the book. The subsequent eight chapters covering: Physical m

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

    Directory of Open Access Journals (Sweden)

    K. Nowacki

    2013-04-01

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

  10. Electro-acoustic shock waves in dusty plasmas

    International Nuclear Information System (INIS)

    Mamun, A.A.; Rahman, A.

    2005-10-01

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

  11. 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.

  12. Mesoscale variations in acoustic signals induced by atmospheric gravity waves.

    Science.gov (United States)

    Chunchuzov, Igor; Kulichkov, Sergey; Perepelkin, Vitaly; Ziemann, Astrid; Arnold, Klaus; Kniffka, Anke

    2009-02-01

    The results of acoustic tomographic monitoring of the coherent structures in the lower atmosphere and the effects of these structures on acoustic signal parameters are analyzed in the present study. From the measurements of acoustic travel time fluctuations (periods 1 min-1 h) with distant receivers, the temporal fluctuations of the effective sound speed and wind speed are retrieved along different ray paths connecting an acoustic pulse source and several receivers. By using a coherence analysis of the fluctuations near spatially distanced ray turning points, the internal wave-associated fluctuations are filtered and their spatial characteristics (coherences, horizontal phase velocities, and spatial scales) are estimated. The capability of acoustic tomography in estimating wind shear near ground is shown. A possible mechanism describing the temporal modulation of the near-ground wind field by ducted internal waves in the troposphere is proposed.

  13. Scattering of Acoustic Waves from Ocean Boundaries

    Science.gov (United States)

    2015-09-30

    at the Target and Reverberation Experiment 2013 (TREX13),” in Proc. IEEE/OES Acoustics in Underwater Geosciences Symposium, Rio de Janeiro , Brazil...a Sandy Seabed at the Target and Reverberation Experiment 2013 (TREX13),” in Proc. IEEE/OES Acoustics in Underwater Geosciences Symposium, Rio de ... Janeiro , Brazil, July 2015. PRESENTATIONS Presenter: Isakson, M.J., Chotiros, N.P., Piper, J.N. and McNeese, A. “Acoustic Scattering from a Sandy Seabed

  14. Resolution Enhancement of Scanning Laser Acoustic Microscope Using Transverse Wave

    International Nuclear Information System (INIS)

    Ko, D. S.; Park, J. S.; Kim, Y. H.

    1997-01-01

    We studied the resolution enhancement of a novel scanning laser acoustic microscope (SLAM) using transverse waves. Mode conversion of the ultrasonic wave takes place at the liquid-solid interface and some energy of the insonifying longitudinal waves in the water will convert to transverse wave energy within the solid specimen. The resolution of SLAM depends on the size of detecting laser spot and the wavelength of the insonifying ultrasonic waves. Science the wavelength of the transverse wave is shorter than that of the longitudinal wave, we are able to achieve the high resolution by using transverse waves. In order to operate SLAM in the transverse wave mode, we made wedge for changing the incident angle. Our experimental results with model 2140 SLAM and an aluminum specimen showed higher contrast of the SLAM image in the transverse wave mode than that in the longitudinal wave mode

  15. Robust Sensing of Approaching Vehicles Relying on Acoustic Cues

    Directory of Open Access Journals (Sweden)

    Mitsunori Mizumachi

    2014-05-01

    Full Text Available The latest developments in automobile design have allowed them to be equipped with various sensing devices. Multiple sensors such as cameras and radar systems can be simultaneously used for active safety systems in order to overcome blind spots of individual sensors. This paper proposes a novel sensing technique for catching up and tracking an approaching vehicle relying on an acoustic cue. First, it is necessary to extract a robust spatial feature from noisy acoustical observations. In this paper, the spatio-temporal gradient method is employed for the feature extraction. Then, the spatial feature is filtered out through sequential state estimation. A particle filter is employed to cope with a highly non-linear problem. Feasibility of the proposed method has been confirmed with real acoustical observations, which are obtained by microphones outside a cruising vehicle.

  16. Cylindrical and spherical dust-acoustic wave modulations in dusty ...

    Indian Academy of Sciences (India)

    Abstract. The nonlinear wave modulation of planar and non-planar (cylindrical and spherical) dust-acoustic waves (DAW) propagating in dusty plasmas, in the presence of non-extensive distribu- tions for ions and electrons is investigated. By employing multiple scales technique, a cylindrically and spherically modified ...

  17. Ion-acoustic solitary waves near double layers

    International Nuclear Information System (INIS)

    Kuehl, H.H.; Imen, K.

    1985-01-01

    The possibility of ion-acoustic solitary-wave solutions in the uniform plasma on the high-potential side of double layer is investigated. Based on a fluid model of the double layer, it is found that both compressive and rarefactive solitary waves are allowed. Curves are presented which show the regions in parameter space in which these solutions exist

  18. INTERFERENCE FRINGES OF SOLAR ACOUSTIC WAVES AROUND SUNSPOTS

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-20

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

  19. 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.

  20. Distributed temperature and distributed acoustic sensing for remote and harsh environments

    Science.gov (United States)

    Mondanos, Michael; Parker, Tom; Milne, Craig H.; Yeo, Jackson; Coleman, Thomas; Farhadiroushan, Mahmoud

    2015-05-01

    Advances in opto-electronics and associated signal processing have enabled the development of Distributed Acoustic and Temperature Sensors. Unlike systems relying on discrete optical sensors a distributed system does not rely upon manufactured sensors but utilises passive custom optical fibre cables resistant to harsh environments, including high temperature applications (600°C). The principle of distributed sensing is well known from the distributed temperature sensor (DTS) which uses the interaction of the source light with thermal vibrations (Raman scattering) to determine the temperature at all points along the fibre. Distributed Acoustic Sensing (DAS) uses a novel digital optical detection technique to precisely capture the true full acoustic field (amplitude, frequency and phase) over a wide dynamic range at every point simultaneously. A number of signal processing techniques have been developed to process a large array of acoustic signals to quantify the coherent temporal and spatial characteristics of the acoustic waves. Predominantly these systems have been developed for the oil and gas industry to assist reservoir engineers in optimising the well lifetime. Nowadays these systems find a wide variety of applications as integrity monitoring tools in process vessels, storage tanks and piping systems offering the operator tools to schedule maintenance programs and maximize service life.

  1. Separation of acoustic waves in isentropic flow perturbations

    International Nuclear Information System (INIS)

    Henke, Christian

    2015-01-01

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

  2. The collapse of acoustic waves in dispersive media

    International Nuclear Information System (INIS)

    Kuznetsov, E.A.; Musher, S.L.; Shafarenko, A.V.

    1983-01-01

    The existence of the collapse of acoustic waves with a positive dispersion is demonstrated. A qualitative description of wave collapse, based on the analysis of invariants, is proposed. Through the use of a numerical simulation, it is established that, in the Kadomtsev-Petviashvili three-dimensional equation, collapse is accompanied by the formation of a weakly turbulent background by the wave radiation from the cavity

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

    International Nuclear Information System (INIS)

    Tsukabayashi, I.; Yagishita, T.; Nakamura, Y.

    1994-01-01

    Electrostatic ion-acoustic waves in a weakly magnetized plasma are investigated experimentally. It is observed that finite amplitudes ion acoustic waves excite a new second harmonic wave train behind the initial ion waves excite a new second harmonic wave train behind the initial ion waves in a parallel magnetic field. The excitation of higher harmonic waves can be explained by non-linearity of finite amplitude ion-acoustic waves. The newly excited second harmonics waves satisfy a dispersion relation of the ion-acoustic waves. (author). 3 refs, 5 figs

  4. Temporal coherence of the acoustic field forward propagated through a continental shelf with random internal waves.

    Science.gov (United States)

    Gong, Zheng; Chen, Tianrun; Ratilal, Purnima; Makris, Nicholas C

    2013-11-01

    An analytical model derived from normal mode theory for the accumulated effects of range-dependent multiple forward scattering is applied to estimate the temporal coherence of the acoustic field forward propagated through a continental-shelf waveguide containing random three-dimensional internal waves. The modeled coherence time scale of narrow band low-frequency acoustic field fluctuations after propagating through a continental-shelf waveguide is shown to decay with a power-law of range to the -1/2 beyond roughly 1 km, decrease with increasing internal wave energy, to be consistent with measured acoustic coherence time scales. The model should provide a useful prediction of the acoustic coherence time scale as a function of internal wave energy in continental-shelf environments. The acoustic coherence time scale is an important parameter in remote sensing applications because it determines (i) the time window within which standard coherent processing such as matched filtering may be conducted, and (ii) the number of statistically independent fluctuations in a given measurement period that determines the variance reduction possible by stationary averaging.

  5. Green function formalism for nonlinear acoustic waves in layered media

    International Nuclear Information System (INIS)

    Lobo, A.; Tsoy, E.; De Sterke, C.M.

    2000-01-01

    Full text: The applications of acoustic waves in identifying defects in adhesive bonds between metallic plates have received little attention at high intensities where the media respond nonlinearly. However, the effects of reduced bond strength are more distinct in the nonlinear response of the structure. Here we assume a weak nonlinearity acting as a small perturbation, thereby reducing the problem to a linear one. This enables us to develop a specialized Green function formalism for calculating acoustic fields in layered media

  6. Electron-acoustic solitary waves in the Earth's inner magnetosphere

    Science.gov (United States)

    Dillard, C. S.; Vasko, I. Y.; Mozer, F. S.; Agapitov, O. V.; Bonnell, J. W.

    2018-02-01

    The broadband electrostatic turbulence observed in the inner magnetosphere is produced by large-amplitude electrostatic solitary waves of generally two types. The solitary waves with symmetric bipolar parallel (magnetic field-aligned) electric field are electron phase space holes. The solitary waves with highly asymmetric bipolar parallel electric field have been recently shown to correspond to the electron-acoustic plasma mode (existing due to two-temperature electron population). Through theoretical and numerical analysis of hydrodynamic and modified Korteweg-de Vries equations, we demonstrate that the asymmetric solitary waves appear due to the steepening of initially quasi-monochromatic electron-acoustic perturbation arrested at some moment by collisionless dissipation (Landau damping). The typical steepening time is found to be from a few to tens of milliseconds. The steepening of the electron-acoustic waves has not been reproduced in self-consistent kinetic simulations yet, and factors controlling the formation of steepened electron-acoustic waves, rather than electron phase space holes, remain unclear.

  7. Laser Generated Leaky Acoustic Waves for Needle Visualization.

    Science.gov (United States)

    Wu, Kai-Wen; Wang, Yi-An; Li, Pai-Chi

    2018-04-01

    Ultrasound (US)-guided needle operation is usually used to visualize both tissue and needle position such as tissue biopsy and localized drug delivery. However, the transducer-needle orientation is limited due to reflection of the acoustic waves. We proposed a leaky acoustic wave method to visualize the needle position and orientation. Laser pulses are emitted on top of the needle to generate acoustic waves; then, these acoustic waves propagate along the needle surface. Leaky wave signals are detected by the US array transducer. The needle position can be calculated by phase velocities of two different wave modes and their corresponding emission angles. In our experiments, a series of needles was inserted into a tissue mimicking phantom and porcine tissue to evaluate the accuracy of the proposed method. The results show that the detection depth is up to 51 mm and the insertion angle is up to 40° with needles of different diameters. It is demonstrated that the proposed approach outperforms the conventional B-mode US-guided needle operation in terms of the detection range while achieving similar accuracy. The proposed method reveals the potentials for further clinical applications.

  8. Towards Noise Tomography and Passive Monitoring Using Distributed Acoustic Sensing

    Science.gov (United States)

    Paitz, P.; Fichtner, A.

    2017-12-01

    Distributed Acoustic Sensing (DAS) has the potential to revolutionize the field of seismic data acquisition. Thanks to their cost-effectiveness, fiber-optic cables may have the capability of complementing conventional geophones and seismometers by filling a niche of applications utilizing large amounts of data. Therefore, DAS may serve as an additional tool to investigate the internal structure of the Earth and its changes over time; on scales ranging from hydrocarbon or geothermal reservoirs to the entire globe. An additional potential may be in the existence of large fibre networks deployed already for telecommunication purposes. These networks that already exist today could serve as distributed seismic antennas. We investigate theoretically how ambient noise tomography may be used with DAS data. For this we extend the theory of seismic interferometry to the measurement of strain. With numerical, 2D finite-difference examples we investigate the impact of source and receiver effects. We study the effect of heterogeneous source distributions and the cable orientation by assessing similarities and differences to the Green's function. We also compare the obtained interferometric waveforms from strain interferometry to displacement interferometric wave fields obtained with existing methods. Intermediate results show that the obtained interferometric waveforms can be connected to the Green's Functions and provide consistent information about the propagation medium. These simulations will be extended to reservoir scale subsurface structures. Future work will include the application of the theory to real-data examples. The presented research depicts the early stage of a combination of theoretical investigations, numerical simulations and real-world data applications. We will therefore evaluate the potentials and shortcomings of DAS in reservoir monitoring and seismology at the current state, with a long-term vision of global seismic tomography utilizing DAS data from

  9. 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.

  10. Nonplanar ion acoustic waves with kappa-distributed electrons

    International Nuclear Information System (INIS)

    Sahu, Biswajit

    2011-01-01

    Using the standard reductive perturbation technique, nonlinear cylindrical and spherical Kadomtsev-Petviashvili equations are derived for the propagation of ion acoustic solitary waves in an unmagnetized collisionless plasma with kappa distributed electrons and warm ions. The influence of kappa-distributed electrons and the effects caused by the transverse perturbation on cylindrical and spherical ion acoustic waves (IAWs) are investigated. It is observed that increase in the kappa distributed electrons (i.e., decreasing κ) decreases the amplitude of the solitary electrostatic potential structures. The numerical results are presented to understand the formation of ion acoustic solitary waves with kappa-distributed electrons in nonplanar geometry. The present investigation may have relevance in the study of propagation of IAWs in space and laboratory plasmas.

  11. Photo-acoustic and video-acoustic methods for sensing distant sound sources

    Science.gov (United States)

    Slater, Dan; Kozacik, Stephen; Kelmelis, Eric

    2017-05-01

    Long range telescopic video imagery of distant terrestrial scenes, aircraft, rockets and other aerospace vehicles can be a powerful observational tool. But what about the associated acoustic activity? A new technology, Remote Acoustic Sensing (RAS), may provide a method to remotely listen to the acoustic activity near these distant objects. Local acoustic activity sometimes weakly modulates the ambient illumination in a way that can be remotely sensed. RAS is a new type of microphone that separates an acoustic transducer into two spatially separated components: 1) a naturally formed in situ acousto-optic modulator (AOM) located within the distant scene and 2) a remote sensing readout device that recovers the distant audio. These two elements are passively coupled over long distances at the speed of light by naturally occurring ambient light energy or other electromagnetic fields. Stereophonic, multichannel and acoustic beam forming are all possible using RAS techniques and when combined with high-definition video imagery it can help to provide a more cinema like immersive viewing experience. A practical implementation of a remote acousto-optic readout device can be a challenging engineering problem. The acoustic influence on the optical signal is generally weak and often with a strong bias term. The optical signal is further degraded by atmospheric seeing turbulence. In this paper, we consider two fundamentally different optical readout approaches: 1) a low pixel count photodiode based RAS photoreceiver and 2) audio extraction directly from a video stream. Most of our RAS experiments to date have used the first method for reasons of performance and simplicity. But there are potential advantages to extracting audio directly from a video stream. These advantages include the straight forward ability to work with multiple AOMs (useful for acoustic beam forming), simpler optical configurations, and a potential ability to use certain preexisting video recordings. However

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

    Science.gov (United States)

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

    2016-01-29

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

  13. Nonlinear excitation of geodesic acoustic modes by drift waves

    International Nuclear Information System (INIS)

    Chakrabarti, N.; Singh, R.; Kaw, P. K.; Guzdar, P. N.

    2007-01-01

    In this paper, two mode-coupling analyses for the nonlinear excitation of the geodesic acoustic modes (GAMs) in tokamak plasmas by drift waves are presented. The first approach is a coherent parametric process, which leads to a three-wave resonant interaction. This investigation allows for the drift waves and the GAMs to have comparable scales. The second approach uses the wave-kinetic equations for the drift waves, which then couples to the GAMs. This requires that the GAM scale length be large compared to the wave packet associated with the drift waves. The resonance conditions for these two cases lead to specific predictions of the radial wave number of the excited GAMs

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

    Directory of Open Access Journals (Sweden)

    Zhi-Kai Fu

    2015-01-01

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

  15. 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.

  16. 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.

  17. 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.

  18. Characteristics of fundamental acoustic wave modes in thin piezoelectric plates.

    Science.gov (United States)

    Joshi, S G; Zaitsev, B D; Kuznetsova, I E; Teplykh, A A; Pasachhe, A

    2006-12-22

    The characteristics of the three lowest order plate waves (A(0), S(0), and SH(0)) propagating in piezoelectric plates whose thickness h is much less than the acoustic wavelength lambda are theoretically analyzed. It is found that these waves can provide much higher values of electromechanical coupling coefficient K(2) and lower values of temperature coefficient of delay (TCD) than is possible with surface acoustic waves (SAWs). For example, in 30Y-X lithium niobate, the SH(0) mode has K(2)=0.46 and TCD=55 ppm/degrees C. The corresponding values for SAW in the widely used, strong coupling material of 128Y-X lithium niobate are K(2)=0.053 and TCD=75 ppm/degrees C. Another important advantage of plate waves is that, unlike the case of SAWs, they can operate satisfactorily in contact with a liquid medium, thus making possible their use in liquid phase sensors.

  19. CHROMOSPHERIC HEATING BY ACOUSTIC WAVES COMPARED TO RADIATIVE COOLING

    Energy Technology Data Exchange (ETDEWEB)

    Sobotka, M.; Heinzel, P.; Švanda, M.; Jurčák, J. [Astronomical Institute, Academy of Sciences of the Czech Republic (v.v.i.), Fričova 298, 25165 Ondřejov (Czech Republic); Del Moro, D.; Berrilli, F. [Department of Physics, University of Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome (Italy)

    2016-07-20

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

  20. Terahertz wave reflective sensing and imaging

    Science.gov (United States)

    Zhong, Hua

    Sensing and imaging technologies using terahertz (THz) radiation have found diverse applications as they approach maturity. Since the burgeoning of this technique in the 1990's, many THz sensing and imaging investigations have been designed and conducted in transmission geometry, which provides sufficient phase and amplitude contrast for the study of the spectral properties of targets in the THz domain. Driven by rising expectations that THz technology will be a potential candidate in the next generation of security screening, remote sensing, biomedical imaging and non-destructive testing (NDT), most THz sensing and imaging modalities are being extended to reflection geometry, which offers unique and adaptive solutions, and multi-dimensional information in many real scenarios. This thesis takes an application-focused approach to the advancement of THz wave reflective sensing and imaging systems: The absorption signature of the explosive material hexahydro-1,3,5-trinitro-1,3,5triazine (RDX) is measured at 30 m---the longest standoff distance so far attained by THz time-domain spectroscopy (THz-TDS). The standoff distance sensing ability of THz-TDS is investigated along with discussions specifying the influences of a variety of factors such as propagation distance, water vapor absorption and collection efficiency. Highly directional THz radiation from four-wave mixing in laser-induced air plasmas is first observed and measured, which provides a potential solution for the atmospheric absorption effect in standoff THz sensing. The simulations of the beam profiles also illuminate the underlying physics behind the interaction of the optical beam with the plasma. THz wave reflective spectroscopic focal-plane imaging is realized the first time. Absorption features of some explosives and related compounds (ERCs) and biochemical materials are identified by using adaptive feature extraction method. Good classification results using multiple pattern recognition methods are

  1. 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.

  2. Propagation of acoustic waves in a stratified atmosphere, 1

    Science.gov (United States)

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

    1994-01-01

    This work is motivated by the chromospheric 3 minute oscillations observed in the K(sub 2v) bright points. We study acoustic gravity waves in a one-dimensional, gravitationally stratified, isothermal atmosphere. The oscillations are excited either by a velocity pulse imparted to a layer in an atmosphere of infinite vertical extent, or by a piston forming the lower boundary of a semi-infinite medium. We consider both linear and non-linear waves.

  3. Generalized collar waves in acoustic logging while drilling

    International Nuclear Information System (INIS)

    Wang Xiu-Ming; He Xiao; Zhang Xiu-Mei

    2016-01-01

    Tool waves, also named collar waves, propagating along the drill collars in acoustic logging while drilling (ALWD), strongly interfere with the needed P- and S-waves of a penetrated formation, which is a key issue in picking up formation P- and S-wave velocities. Previous studies on physical insulation for the collar waves designed on the collar between the source and the receiver sections did not bring to a satisfactory solution. In this paper, we investigate the propagation features of collar waves in different models. It is confirmed that there exists an indirect collar wave in the synthetic full waves due to the coupling between the drill collar and the borehole, even there is a perfect isolator between the source and the receiver. The direct collar waves propagating all along the tool and the indirect ones produced by echoes from the borehole wall are summarized as the generalized collar waves. Further analyses show that the indirect collar waves could be relatively strong in the full wave data. This is why the collar waves cannot be eliminated with satisfactory effect in many cases by designing the physical isolators carved on the tool. (special topic)

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

    OpenAIRE

    Salo, Janne

    2003-01-01

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

  5. Simultaneous realization of slow and fast acoustic waves using a fractal structure of Koch curve.

    Science.gov (United States)

    Ding, Jin; Fan, Li; Zhang, Shu-Yi; Zhang, Hui; Yu, Wei-Wei

    2018-01-24

    An acoustic metamaterial based on a fractal structure, the Koch curve, is designed to simultaneously realize slow and fast acoustic waves. Owing to the multiple transmitting paths in the structure resembling the Koch curve, the acoustic waves travelling along different paths interfere with each other. Therefore, slow waves are created on the basis of the resonance of a Koch-curve-shaped loop, and meanwhile, fast waves even with negative group velocities are obtained due to the destructive interference of two acoustic waves with opposite phases. Thus, the transmission of acoustic wave can be freely manipulated with the Koch-curve shaped structure.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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,

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

    Indian Academy of Sciences (India)

    Abstract. Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized two- species relativistic quantum plasma system, comprised of electrons and ions. The one-dimensional quantum hydrodynamic model (QHD) is used to obtain a deformed Korteweg–de Vries (dKdV) equation by reductive ...

  12. Ion Acoustic Waves in the Presence of Langmuir Oscillations

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1976-01-01

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

  13. Acoustic waves in shock tunnels and expansion tubes

    Science.gov (United States)

    Paull, A.; Stalker, R. J.

    1992-01-01

    It is shown that disturbances in shock and expansion tubes can be modelled as lateral acoustic waves. The ratio of sound speed across the driver-test gas interface is shown to govern the quantity of noise in the test gas. Frequency 'focusing' which is fundamental to centered unsteady expansions is discussed and displayed in centerline pitot pressure measurements.

  14. 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.

  15. Reflector stack optimization for Bulk Acoustic Wave resonators

    NARCIS (Netherlands)

    Jose, Sumy

    2011-01-01

    Thin-film bulk-acoustic-wave (BAW) devices are used for RF selectivity in mobile communication system and other wireless applications. Currently, the conventional RF filters are getting replaced by BAW filters in all major cell phone standards. In this thesis, we study solidly mounted BAW resonators

  16. Exact solitary ion acoustic waves in a magnetoplasma

    International Nuclear Information System (INIS)

    Ray, D.

    1979-01-01

    Solitary ion acoustic waves in a magnetoplasma have been studied by Shukla and Yu [J. Math. Phys. 19, 2506 (1978)]. A more rigorous study confirms the conditions that Shukla and Yu said would be necessary for humps. However, it is shown that a density cavity is also possible in the limiting case

  17. Dromion solutions for an electron acoustic wave and its application ...

    Indian Academy of Sciences (India)

    Davey–Stewartson equation; electron acoustic wave; space plasma. ... Its potential application in different physical fields are also well .... bi-linear method. .... One of the authors, S S Ghosh, would like to thank CSIR for its financial assistance ...

  18. Signal Processing of Underwater Acoustic Waves

    Science.gov (United States)

    1969-11-01

    for the interest they have shown in the work and for many helpful discussions. The book was supported by Naval Ship Systems Corn- mand tinder ...inclination of the ray. The relationship is such that for the maximum values of dnldz just quoted radius of 0ectromapnetic ray 2,0 radius of acoustic... relationship for the angles, in, of the geometric ray, and carry out the limiting process as h -- 0. Show that when the velocity func- tion c(z) is

  19. Velocity profiles of acoustic streaming in resulting stokes layer by acoustic standing wave in a duct; Kannai kichi shindo ni okeru stokes sonai onkyoryu ryusoku bunpu no kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Arakawa, M; Kawahashi, M [Saitama University, Saitama (Japan). Faculty of Engineering

    1995-07-25

    Acoustic streaming is generated by Reynolds stress in the sense of mean acoustic momentum flux in a sound field. In the case of an acoustic standing wave produced by an air column oscillation in a closed duct, the friction and the Reynolds stress in the resulting Stokes layer are the essentials of acoustic streaming generation in the vicinity of the duct wall. The thickness of the Stokes layer decreases with the oscillatory Reynolds number. The plane wave propagation in the duct is assumed for the case of high Reynolds number except for the thin Stokes layer adjacent to the duct wall. The velocity profiles of the streaming are estimated theoretically from the steady component of the second-order term of a perturbation expansion in which the first-order approximation is a sinusoidal oscillation of the air column with plane waves. The present paper describes theoretical analysis of the velocity profiles of the acoustic streaming in the Stokes layer by means of the matched asymptotic expansion method. The results obtained show the existence of reverse streaming in a very thin layer adjacent to the wall and the effects of thermal boundary conditions at the wall on the velocity profiles of acoustic streaming in the Stokes layer. 9 refs., 8 figs.

  20. Optical and acoustic sensing using Fano-like resonances in dual phononic and photonic crystal plate

    DEFF Research Database (Denmark)

    Amoudache, Samira; Moiseyenko, Rayisa; Pennec, Yan

    2016-01-01

    We perform a theoretical study based on the transmissions of optical and acoustic waves normally impinging to a periodic perforated silicon plate when the embedded medium is a liquid and show the existence of Fano-like resonances in both cases. The signature of the resonances appears as well-defi...... of standing waves confined inside the cavity coming from the deformation of the water/silicon edges of the cylindrical inclusion. We finally use these features for sensing and show ultra-sensitivity to the light and sound velocities for different concentrations of analytes.......-defined asymmetric peaks in the phononic and photonic transmission spectra. We show that the origin of the Fano-like resonances is different with respect to the nature of the wave. In photonic, the origin comes from guided modes in the photonic plate while in phononic we show that it comes from the excitation...

  1. Optical and acoustic sensing using Fano-like resonances in dual phononic and photonic crystal plate

    Energy Technology Data Exchange (ETDEWEB)

    Amoudache, Samira [Institut d' Electronique, de Microélectronique et de Nanotechnologie, Université de Lille 1, 59655 Villeneuve d' Ascq (France); Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri, B.P. 17 RP, 15000 Tizi-Ouzou (Algeria); Moiseyenko, Rayisa [Department of Physics, Technical University of Denmark, DTU Physics, Building 309, DK-2800 Kongens Lyngby (Denmark); Pennec, Yan, E-mail: yan.pennec@univ-lille1.fr; Rouhani, Bahram Djafari [Institut d' Electronique, de Microélectronique et de Nanotechnologie, Université de Lille 1, 59655 Villeneuve d' Ascq (France); Khater, Antoine [Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, l' UNAM, Université du Maine, 72085 Le Mans (France); Lucklum, Ralf [Institute of Micro and Sensor Systems (IMOS), Otto-von-Guericke-University, P.O. Box 4120, D-39016 Magdeburg (Germany); Tigrine, Rachid [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri, B.P. 17 RP, 15000 Tizi-Ouzou (Algeria)

    2016-03-21

    We perform a theoretical study based on the transmissions of optical and acoustic waves normally impinging to a periodic perforated silicon plate when the embedded medium is a liquid and show the existence of Fano-like resonances in both cases. The signature of the resonances appears as well-defined asymmetric peaks in the phononic and photonic transmission spectra. We show that the origin of the Fano-like resonances is different with respect to the nature of the wave. In photonic, the origin comes from guided modes in the photonic plate while in phononic we show that it comes from the excitation of standing waves confined inside the cavity coming from the deformation of the water/silicon edges of the cylindrical inclusion. We finally use these features for sensing and show ultra-sensitivity to the light and sound velocities for different concentrations of analytes.

  2. Dust acoustic shock wave at high dust density

    International Nuclear Information System (INIS)

    Ghosh, Samiran; Sarkar, Susmita; Khan, Manoranjan; Avinash, K.; Gupta, M. R.

    2003-01-01

    Dust acoustic (DA) shock wave at high dust density, i.e., the dust electroacoustic (DEA) or dust Coulomb (DC) shock wave has been investigated incorporating the nonadiabatic dust charge variation. The nonlinear DEA (DC) shock wave is seen to be governed by the Korteweg-de Vries Burger equation, in which the Burger term is proportional to the nonadiabaticity generated dissipation. It is seen that the shock strength decreases but after reaching minimum, it increases as the dust space charge density |q d n d | increases and the shock strength of DA wave is greater than that of DEA (DC) wave. Moreover the DEA (DC) shock width increases appreciably with increase mass m i of the ion component of the dusty plasma but for DA shock wave the effect is weak

  3. Opportunities for shear energy scaling in bulk acoustic wave resonators.

    Science.gov (United States)

    Jose, Sumy; Hueting, Raymond J E

    2014-10-01

    An important energy loss contribution in bulk acoustic wave resonators is formed by so-called shear waves, which are transversal waves that propagate vertically through the devices with a horizontal motion. In this work, we report for the first time scaling of the shear-confined spots, i.e., spots containing a high concentration of shear wave displacement, controlled by the frame region width at the edge of the resonator. We also demonstrate a novel methodology to arrive at an optimum frame region width for spurious mode suppression and shear wave confinement. This methodology makes use of dispersion curves obtained from finite-element method (FEM) eigenfrequency simulations for arriving at an optimum frame region width. The frame region optimization is demonstrated for solidly mounted resonators employing several shear wave optimized reflector stacks. Finally, the FEM simulation results are compared with measurements for resonators with Ta2O5/ SiO2 stacks showing suppression of the spurious modes.

  4. 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...

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

    International Nuclear Information System (INIS)

    Zhang Zhe; Li Rui-Qi; Liang Bin; Zou Xin-Ye; Cheng Jian-Chun

    2015-01-01

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

  6. Dislocation kinetics and the acoustic-wave approximation for liquids

    International Nuclear Information System (INIS)

    Stout, R.B.

    1983-03-01

    A dislocation-dependent model for liquids describes the lattice deformation and the fluidity deformation as additive deformations. The lattice deformation represents distortions of an atom's potential energy structure and is a recoverable deformation response. The fluidity deformation represents discontinuous repositioning of atoms by dislocation kinetics in the lattice structure and is a nonrecoverable deformation response. From this model, one concludes that in liquids the acoustic-wave approximation is a description of a recoverable oscillation deformation that has dissipation because of dislocation kinetics. Other more-complex waves may exist, but such waves would rapidly disappear because of the small thermodynamic potential for dislocation kinetics in liquids

  7. 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.

  8. Nonlinear acoustic waves in partially ionized collisional plasmas

    International Nuclear Information System (INIS)

    Rao, N.N.; Kaup, D.J.; Shukla, P.K.

    1991-01-01

    Nonlinear propagation of acoustic-type waves in a partially ionized three-component collisional plasma consisting of electrons, ions and neutral particles is investigated. For bidirectional propagation, it is shown that the small- but finite-amplitude waves are governed by the Boussinesq equation, which for unidirectional propagation near the acoustic speed reduces to the usual Korteweg-de Vries equation. For large-amplitude waves, it is demonstrated that the relevant fluid equations are integrable in a stationary frame, and the parameter values for the existence of finite-amplitude solutions are explicitly obtained. In both cases, the different temperatures of the individual species, are taken into account. The relevance of the results to the earth's ionospheric plasma in the lower altitude ranges is pointed out. (author)

  9. Acoustic waves in M dwarfs: Maintaining a corona

    Science.gov (United States)

    Mullan, D. J.; Cheng, Q. Q.

    1994-01-01

    We use a time-dependent hydrodynamics code to follow the propagation of acoustic waves into the corona of an M dwarf star. An important qualitative difference between M dwarfs and stars such as the Sun is that the acoustic spectrum in M dwarfs is expected to peak at periods close to the acoustic cutoff P(sub A): this allows more effective penetration of waves into the corona. In our code, radiative losses in the photosphere, chromosphere, and corona are computed using Rosseland mean opacities, Mg II kappa and Ly alpha emission, and optically thin emissivities respectively. We find that acoustic heating can maintain a corona with a temperature of order 0.7-1 x 10(exp 6) K and a surface X-ray flux as large as 10(exp 5)ergs/sq cm/s. In a recent survey of X-rays from M dwarfs, some (20%-30%) of the stars lie at or below this limiting X-ray flux: we suggest that such stars may be candidates for acoustically maintained coronae.

  10. 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.

  11. 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

  12. Acoustic wave focusing in an ellipsoidal reflector for extracorporeal shock-wave lithotripsy

    Science.gov (United States)

    Lottati, Itzhak; Eidelman, Shmuel

    1993-07-01

    Simulations of acoustic wave focusing in an ellipsoidal reflector for extracorporeal shock-wave lithotripsy (ESWL) are presented. The simulations are done on a structured/unstructured grid with a modified Tait equation of state for water. The Euler equations are solved by applying a second-order Godunov method. The computed results compare very well with the experimental results.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  14. 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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-15

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

  17. Selective generation of ultrasonic Lamb waves by electromagnetic acoustic transducers

    International Nuclear Information System (INIS)

    Li Ming-Liang; Deng Ming-Xi; Gao Guang-Jian

    2016-01-01

    In this paper, we describe a modal expansion approach for the analysis of the selective generation of ultrasonic Lamb waves by electromagnetic acoustic transducers (EMATs). With the modal expansion approach for waveguide excitation, an analytical expression of the Lamb wave’s mode expansion coefficient is deduced, which is related to the driving frequency and the geometrical parameters of the EMAT’s meander coil, and lays a theoretical foundation for exactly analyzing the selective generation of Lamb waves with EMATs. The influences of the driving frequency on the mode expansion coefficient of ultrasonic Lamb waves are analyzed when the EMAT’s geometrical parameters are given. The numerical simulations and experimental examinations show that the ultrasonic Lamb wave modes can be effectively regulated (strengthened or restrained) by choosing an appropriate driving frequency of EMAT, with the geometrical parameters given. This result provides a theoretical and experimental basis for selectively generating a single and pure Lamb wave mode with EMATs. (special topic)

  18. Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

    Directory of Open Access Journals (Sweden)

    Shilei Liu

    2017-07-01

    Full Text Available Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF and acoustic streaming (AS. In this paper, force conditions on micrometer size polystyrene microspheres in acoustic standing wave fields were investigated. The COMSOL® Mutiphysics particle tracing module was used to numerically simulate force conditions on various particles as a function of time. The velocity of particle movement was experimentally measured using particle imaging velocimetry (PIV. Through experimental and numerical simulation, the functions of ARF and AS in trapping and patterning were analyzed. It is shown that ARF is dominant in trapping and patterning large particles while the impact of AS increases rapidly with decreasing particle size. The combination of using both ARF and AS for medium size particles can obtain different patterns with only using ARF. Findings of the present study will aid the design of acoustic-driven microfluidic devices to increase the diversity of particle patterning.

  19. Investigation into the Effect of Acoustic Radiation Force and Acoustic Streaming on Particle Patterning in Acoustic Standing Wave Fields

    Science.gov (United States)

    Yang, Yanye; Ni, Zhengyang; Guo, Xiasheng; Luo, Linjiao; Tu, Juan; Zhang, Dong

    2017-01-01

    Acoustic standing waves have been widely used in trapping, patterning, and manipulating particles, whereas one barrier remains: the lack of understanding of force conditions on particles which mainly include acoustic radiation force (ARF) and acoustic streaming (AS). In this paper, force conditions on micrometer size polystyrene microspheres in acoustic standing wave fields were investigated. The COMSOL® Mutiphysics particle tracing module was used to numerically simulate force conditions on various particles as a function of time. The velocity of particle movement was experimentally measured using particle imaging velocimetry (PIV). Through experimental and numerical simulation, the functions of ARF and AS in trapping and patterning were analyzed. It is shown that ARF is dominant in trapping and patterning large particles while the impact of AS increases rapidly with decreasing particle size. The combination of using both ARF and AS for medium size particles can obtain different patterns with only using ARF. Findings of the present study will aid the design of acoustic-driven microfluidic devices to increase the diversity of particle patterning. PMID:28753955

  20. Tuneable film bulk acoustic wave resonators

    CERN Document Server

    Gevorgian, Spartak Sh; Vorobiev, Andrei K

    2013-01-01

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

  1. Analysis of Measured and Simulated Supraglottal Acoustic Waves.

    Science.gov (United States)

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

    2016-09-01

    To date, although much attention has been paid to the estimation and modeling of the voice source (ie, the glottal airflow volume velocity), the measurement and characterization of the supraglottal pressure wave have been much less studied. Some previous results have unveiled that the supraglottal pressure wave has some spectral resonances similar to those of the voice pressure wave. This makes the supraglottal wave partially intelligible. Although the explanation for such effect seems to be clearly related to the reflected pressure wave traveling upstream along the vocal tract, the influence that nonlinear source-filter interaction has on it is not as clear. This article provides an insight into this issue by comparing the acoustic analyses of measured and simulated supraglottal and voice waves. Simulations have been performed using a high-dimensional discrete vocal fold model. Results of such comparative analysis indicate that spectral resonances in the supraglottal wave are mainly caused by the regressive pressure wave that travels upstream along the vocal tract and not by source-tract interaction. On the contrary and according to simulation results, source-tract interaction has a role in the loss of intelligibility that happens in the supraglottal wave with respect to the voice wave. This loss of intelligibility mainly corresponds to spectral differences for frequencies above 1500 Hz. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  2. A three-microphone acoustic reflection technique using transmitted acoustic waves in the airway.

    Science.gov (United States)

    Fujimoto, Yuki; Huang, Jyongsu; Fukunaga, Toshiharu; Kato, Ryo; Higashino, Mari; Shinomiya, Shohei; Kitadate, Shoko; Takahara, Yutaka; Yamaya, Atsuyo; Saito, Masatoshi; Kobayashi, Makoto; Kojima, Koji; Oikawa, Taku; Nakagawa, Ken; Tsuchihara, Katsuma; Iguchi, Masaharu; Takahashi, Masakatsu; Mizuno, Shiro; Osanai, Kazuhiro; Toga, Hirohisa

    2013-10-15

    The acoustic reflection technique noninvasively measures airway cross-sectional area vs. distance functions and uses a wave tube with a constant cross-sectional area to separate incidental and reflected waves introduced into the mouth or nostril. The accuracy of estimated cross-sectional areas gets worse in the deeper distances due to the nature of marching algorithms, i.e., errors of the estimated areas in the closer distances accumulate to those in the further distances. Here we present a new technique of acoustic reflection from measuring transmitted acoustic waves in the airway with three microphones and without employing a wave tube. Using miniaturized microphones mounted on a catheter, we estimated reflection coefficients among the microphones and separated incidental and reflected waves. A model study showed that the estimated cross-sectional area vs. distance function was coincident with the conventional two-microphone method, and it did not change with altered cross-sectional areas at the microphone position, although the estimated cross-sectional areas are relative values to that at the microphone position. The pharyngeal cross-sectional areas including retropalatal and retroglossal regions and the closing site during sleep was visualized in patients with obstructive sleep apnea. The method can be applicable to larger or smaller bronchi to evaluate the airspace and function in these localized airways.

  3. Simulation of Asymmetric Lamb Waves for Sensing and Actuation in Plates

    Directory of Open Access Journals (Sweden)

    A. Ghoshal

    2005-01-01

    Full Text Available Two approaches used for monitoring the health of thin aerospace structures are active interrogation and passive monitoring. The active interrogation approach generates and receives diagnostic Lamb waves to detect damage, while the passive monitoring technique listens for acoustic waves caused by damage growth. For the application of both methods, it is necessary to understand how Lamb waves propagate through a structure. In this paper, a Physics-Based Model (PBM using classical plate theory is developed to provide a basic understanding of the actual physical process of asymmetric Lamb mode wave generation and propagation in a plate. The closed-form model uses modal superposition to simulate waves generated by piezoceramic patches and by simulated acoustic emissions. The generation, propagation, reflection, interference, and the sensing of the waves are represented in the model, but damage is not explicitly modeled. The developed model is expected to be a useful tool for the Structural Health Monitoring (SHM community, particularly for studying high frequency acoustic wave generation and propagation in lieu of Finite Element models and other numerical models that require significant computational resources. The PBM is capable of simulating many possible scenarios including a variety of test cases, whereas experimental measurements of all of the cases can be costly and time consuming. The model also incorporates the sensor measurement effect, which is an important aspect in damage detection. Continuous and array sensors are modeled, which are efficient for measuring waves because of their distributed nature.

  4. Dust confinement and dust acoustic waves in a magnetized plasma

    Science.gov (United States)

    Piel, A.

    2005-10-01

    Systematic laboratory experiments on dust acoustic waves require the confinement of dust particles. Here we report on new experiments in a magnetized plasma region in front of an additional positively biased disk electrode in a background plasma which is generated in argon at 27MHz between a disk and grid electrode. The plasma diffuses through the grid along the magnetic field. The three-dimensional dust distribution is measured with a horizontal sheet of laser light and a CCD camera, which are mounted on a vertical translation stage. Depending on magnetic field and discharge current, cigar or donut-shaped dust clouds are generated, which tend to rotate about the magnetic field direction. Measurements with emissive probes show that the axial confinement of dust particles with diameters between 0.7-2 μm is achieved by a balance of ion-drag force and electric field force. Dust levitation and radial confinement is due to a strong radial electric field. Dust acoustic waves are destabilized by the ion flow or can be stimulated by a periodic bias on the disk electrode. The observed wave dispersion is compared with fluid and kinetic models of the dust acoustic wave.

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

    Directory of Open Access Journals (Sweden)

    Aliza Aini Md Ralib

    2014-12-01

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

  6. Observation of refraction and convergence of ion acoustic waves in a plasma with a temperature gradient

    International Nuclear Information System (INIS)

    Nishida, Y.; Hirose, A.

    1977-01-01

    The refraction and convergence of ion acoustic waves are experimentally investigated in a magnetized plasma with an electron temperature gradient. When ion acoustic waves are launched parallel to the field lines the waves converge toward the interior of the plasma column where the electron temperature is lower, in good agreement with theoretical prediction. Wave interference is also observed. (author)

  7. Standing wave acoustic levitation on an annular plate

    Science.gov (United States)

    Kandemir, Mehmet Hakan; Çalışkan, Mehmet

    2016-11-01

    In standing wave acoustic levitation technique, a standing wave is formed between a source and a reflector. Particles can be attracted towards pressure nodes in standing waves owing to a spring action through which particles can be suspended in air. This operation can be performed on continuous structures as well as in several numbers of axes. In this study an annular acoustic levitation arrangement is introduced. Design features of the arrangement are discussed in detail. Bending modes of the annular plate, known as the most efficient sound generation mechanism in such structures, are focused on. Several types of bending modes of the plate are simulated and evaluated by computer simulations. Waveguides are designed to amplify waves coming from sources of excitation, that are, transducers. With the right positioning of the reflector plate, standing waves are formed in the space between the annular vibrating plate and the reflector plate. Radiation forces are also predicted. It is demonstrated that small particles can be suspended in air at pressure nodes of the standing wave corresponding to a particular bending mode.

  8. 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.

  9. Observation of large-amplitude ion acoustic wave in microwave-plasma interaction experiments

    International Nuclear Information System (INIS)

    Yugami, Noboru; Nishida, Yasushi

    1997-01-01

    Large amplitude ion acoustic wave, which is not satisfied with a linear dispersion relationship of ion acoustic wave, is observed in microwave-plasma interaction experiments. This ion acoustic wave is excited around critical density layer and begins to propagate to underdense region with a phase velocity one order faster than sound velocity C s , which is predicted by the linear theory, the phase velocity and the wave length of the wave decreases as it propagates. Finally, it converges to C s and strongly dumps. Diagnostic by the Faraday cup indicates that this ion acoustic wave is accompanied with a hot ion beam. (author)

  10. Laser-generated acoustic wave studies on tattoo pigment

    Science.gov (United States)

    Paterson, Lorna M.; Dickinson, Mark R.; King, Terence A.

    1996-01-01

    A Q-switched alexandrite laser (180 ns at 755 nm) was used to irradiate samples of agar embedded with red, black and green tattoo dyes. The acoustic waves generated in the samples were detected using a PVDF membrane hydrophone and compared to theoretical expectations. The laser pulses were found to generate acoustic waves in the black and green samples but not in the red pigment. Pressures of up to 1.4 MPa were produced with irradiances of up to 96 MWcm-2 which is comparable to the irradiances used to clear pigment embedded in skin. The pressure gradient generated across pigment particles was approximately 1.09 X 1010 Pam-1 giving a pressure difference of 1.09 +/- 0.17 MPa over a particle with mean diameter 100 micrometers . This is not sufficient to permanently damage skin which has a tensile strength of 7.4 MPa.

  11. 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.

  12. 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.

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

    Science.gov (United States)

    Bhatnagar, N.; Peterson, A. M.

    1979-01-01

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

  14. Fully kinetic simulation of ion acoustic and dust-ion acoustic waves

    International Nuclear Information System (INIS)

    Hosseini Jenab, S. M.; Kourakis, I.; Abbasi, H.

    2011-01-01

    A series of numerical simulations is presented, based on a recurrence-free Vlasov kinetic model using kinetic phase point trajectories. All plasma components are modeled kinetically via a Vlasov evolution equation, then coupled through Poisson's equation. The dynamics of ion acoustic waves in an electron-ion and in a dusty (electron-ion-dust) plasma configuration are investigated, focusing on wave decay due to Landau damping and, in particular, on the parametric dependence of the damping rate on the dust concentration and on the electron-to-ion temperature ratio. In the absence of dust, the occurrence of damping was observed, as expected, and its dependence to the relative magnitude of the electron vs ion temperature(s) was investigated. When present, the dust component influences the charge balance, enabling dust-ion acoustic waves to survive Landau damping even in the extreme regime where T e ≅ T i . The Landau damping rate is shown to be minimized for a strong dust concentration or/and for a high value of the electron-to-ion temperature ratio. Our results confirm earlier theoretical considerations and contribute to the interpretation of experimental observations of dust-ion acoustic wave characteristics.

  15. Simulation of the acoustic wave propagation using a meshless method

    Directory of Open Access Journals (Sweden)

    Bajko J.

    2017-01-01

    Full Text Available This paper presents numerical simulations of the acoustic wave propagation phenomenon modelled via Linearized Euler equations. A meshless method based on collocation of the strong form of the equation system is adopted. Moreover, the Weighted least squares method is used for local approximation of derivatives as well as stabilization technique in a form of spatial ltering. The accuracy and robustness of the method is examined on several benchmark problems.

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

    International Nuclear Information System (INIS)

    Jeannot, Jean-Philippe; Baque, François; Cavaro, Matthieu; Gastaldi, Olivier; Lhuilier, Christian; Massacret, Nicolas; Moriot, Jérémy; Paumel, Kévin; Vandergaegen, Matthias; Rodriguez, Gilles

    2013-01-01

    Improvement to prevent core meltdown and to provide a more robust safety demonstration → Safety objectives: - A level of safety at least equivalent to EPR’s level, - Consolidation of the defence-in-depth principle, - A more robust safety demonstration than those of the Phenix and Superphenix reactor. Acoustic techniques: - Low attenuation by the sodium medium - High velocity of US wave (2289 m.s-1 at 550°C) →

  18. 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.

  19. Investigation of Ion Acoustic Waves in Collisionless Plasmas

    DEFF Research Database (Denmark)

    Christoffersen, G. B.; Jensen, Vagn Orla; Michelsen, Poul

    1974-01-01

    The Green's functions for the linearized ion Vlasov equation with a given boundary value are derived. The propagation properties of ion acoustic waves are calculated by performing convolution integrals over the Green's functions. For Te/Ti less than about 3 it is concluded that the collective...... interaction is very weak and that the propagation properties are determined almost completely by freely streaming ions. The wave damping, being due to phase mixing, is determined by the width of the perturbed distribution function rather than by the slope of the undisturbed distribution function at the phase...

  20. Self similar asymptotics of the drift ion acoustic waves

    International Nuclear Information System (INIS)

    Taranov, V.B.

    2004-01-01

    A 3D model for the coupled drift and ion acoustic waves is considered. It is shown that self-similar solutions can exist due to the symmetry extension in asymptotic regimes. The form of these solutions is determined in the presence of the magnetic shear as well as in the shear less case. Some of the most symmetric exact solutions are obtained explicitly. In particular, solutions describing asymptotics of zonal flow interaction with monochromatic waves are presented and corresponding frequency shifts are determined

  1. Manipulating acoustic wave reflection by a nonlinear elastic metasurface

    Science.gov (United States)

    Guo, Xinxin; Gusev, Vitalyi E.; Bertoldi, Katia; Tournat, Vincent

    2018-03-01

    The acoustic wave reflection properties of a nonlinear elastic metasurface, derived from resonant nonlinear elastic elements, are theoretically and numerically studied. The metasurface is composed of a two degree-of-freedom mass-spring system with quadratic elastic nonlinearity. The possibility of converting, during the reflection process, most of the fundamental incoming wave energy into the second harmonic wave is shown, both theoretically and numerically, by means of a proper design of the nonlinear metasurface. The theoretical results from the harmonic balance method for a monochromatic source are compared with time domain simulations for a wave packet source. This protocol allows analyzing the dynamics of the nonlinear reflection process in the metasurface as well as exploring the limits of the operating frequency bandwidth. The reported methodology can be applied to a wide variety of nonlinear metasurfaces, thus possibly extending the family of exotic nonlinear reflection processes.

  2. Acoustic nonlinear periodic waves in pair-ion plasmas

    Science.gov (United States)

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

    2013-09-01

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

  3. Energy scavenging system by acoustic wave and integrated wireless communication

    Science.gov (United States)

    Kim, Albert

    The purpose of the project was developing an energy-scavenging device for other bio implantable devices. Researchers and scientist have studied energy scavenging method because of the limitation of traditional power source, especially for bio-implantable devices. In this research, piezoelectric power generator that activates by acoustic wave, or music was developed. Follow by power generator, a wireless communication also integrated with the device for monitoring the power generation. The Lead Zirconate Titanate (PZT) bimorph cantilever with a proof mass at the free end tip was studied to convert acoustic wave to power. The music or acoustic wave played through a speaker to vibrate piezoelectric power generator. The LC circuit integrated with the piezoelectric material for purpose of wireless monitoring power generation. However, wireless monitoring can be used as wireless power transmission, which means the signal received via wireless communication also can be used for power for other devices. Size of 74 by 7 by 7cm device could generate and transmit 100mVp from 70 mm distance away with electrical resonant frequency at 420.2 kHz..

  4. 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.

  5. 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.

  6. Guided wave opto-acoustic device

    Science.gov (United States)

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

    2016-02-23

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

  7. Theory of the acoustic instability and behavior of the phase velocity of acoustic waves in a weakly ionized plasma

    International Nuclear Information System (INIS)

    Torosyan, O.S.; Mkrtchyan, A.R.

    2003-01-01

    The amplification of acoustic waves due to the transfer of thermal energy from electrons to the neutral component of a glow discharge plasma is studied theoretically. It is shown that, in order for acoustic instability (sound amplification) to occur, the amount of energy transferred should exceed the threshold energy, which depends on the plasma parameters and the acoustic wave frequency. The energy balance equation for an electron gas in the positive column of a glow discharge is analyzed for conditions typical of experiments in which acoustic wave amplification has been observed. Based on this analysis, one can affirm that, first, the energy transferred to neutral gas in elastic electron-atom collisions is substantially lower than the threshold energy for acoustic wave amplification and, second, that the energy transferred from electrons to neutral gas in inelastic collisions is much higher than that transferred in elastic collisions and thus may exceed the threshold energy. It is also shown that, for amplification to occur, there should exist some heat dissipation mechanism more efficient than gas heat conduction. It is suggested that this may be convective radial mixing within a positive column due to acoustic streaming in the field of an acoustic wave. The features of the phase velocity of sound waves in the presence of acoustic instability are investigated

  8. Bounded dust-acoustic waves in a cylindrically bounded collisional dusty plasma with dust charge variation

    International Nuclear Information System (INIS)

    Wei Nanxia; Xue Jukui

    2006-01-01

    Taking into account the boundary, particle collisions, and dust charging effects, dust-acoustic waves in a uniform cylindrically bounded dusty plasma is investigated analytically, and the dispersion relation for the dust-acoustic wave is obtained. The effects of boundary, dust charge variation, particle collision, and dust size on the dust-acoustic wave are discussed in detail. Due to the bounded cylindrical boundary effects, the radial wave number is discrete, i.e., the spectrum is discrete. It is shown that the discrete spectrum, the adiabatic dust charge variation, dust grain size, and the particle collision have significant effects on the dust-acoustic wave

  9. Wave Breaking, Bubble Production and Acoustic Characteristics of the Surf Zone, SIO Component

    National Research Council Canada - National Science Library

    Deane, Grant

    2001-01-01

    .... The purpose of these measurements was to: (1) statistically characterize the surf zone acoustic channel Doppler and time spreads, and acoustic drop-outs, in terms of the incident wave field and (2...

  10. Microscale anechoic architecture: acoustic diffusers for ultra low power microparticle separation via traveling surface acoustic waves.

    Science.gov (United States)

    Behrens, Jan; Langelier, Sean; Rezk, Amgad R; Lindner, Gerhard; Yeo, Leslie Y; Friend, James R

    2015-01-07

    We present a versatile and very low-power traveling SAW microfluidic sorting device able to displace and separate particles of different diameter in aqueous suspension; the travelling wave propagates through the fluid bulk and diffuses via a Schröder diffuser, adapted from its typical use in concert hall acoustics to be the smallest such diffuser to be suitable for microfluidics. The effective operating power range is two to three orders of magnitude less than current SAW devices, uniquely eliminating the need for amplifiers, and by using traveling waves to impart forces directly upon suspended microparticles, they can be separated by size.

  11. 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.

  12. Nonlinear dust-ion-acoustic waves in a multi-ion plasma with ...

    Indian Academy of Sciences (India)

    The basic features of such dust-ion-acoustic solitary and shock waves have been ... ion plasmas because of its vital role in understanding different types of ... cannot support the usual ion-acoustic waves, but can support the DIA waves of ...

  13. Nonlinear response and bistability of driven ion acoustic waves

    Science.gov (United States)

    Akbari-Moghanjoughi, M.

    2017-08-01

    The hydrodynamic model is used to obtain a generalized pseudoforce equation through which the nonlinear response of periodically driven ion acoustic waves is studied in an electron-ion plasma with isothermal and adiabatic ion fluids. The pseudotime series, corresponding to different driving frequencies, indicates that nonlinearity effects appear more strongly for smaller frequency values. The existence of extra harmonic resonances in the nonlinear amplitude spectrum is a clear indication of the interaction of an external force with harmonic components of the nonlinear ion acoustic waves. It is shown that many plasma parameters significantly and differently affect the nonlinear resonance spectrum of ion acoustic excitations. A heuristic but accurate model for the foldover effect is used which quite satisfactorily predicts the bistability of driven plasma oscillations. It is remarked that the characteristic resonance peak of isothermal ion plasma oscillations appears at lower frequencies but is stronger compared to that of adiabatic ions. Comparison of the exact numerical results for fully nonlinear and approximate (weakly nonlinear) models indicates that a weakly nonlinear model exaggerates the hysteresis and jump phenomenon for higher values of the external force amplitude.

  14. Determination of P – wave arrival time of acoustic events

    Directory of Open Access Journals (Sweden)

    Matěj Petružálek

    2010-10-01

    Full Text Available The new approach to the P-wave arrival time determination based on acoustic emission data from loading experiments is tested.The algorithm used in this paper is built on the STA/LTA function computed by a convolution that speeds up the computation processvery much. The picking process makes use of shifting of temporary onset until certain conditions are fulfill and as a main decisioncriterion on the threshold exceeding of the STA/LTA derivation function is used. The P-wave onset time is determined in a selectedinterval that corresponds to the theoretical propagation of elastic wave in the rock sample. Results obtained by our algorithm werecorrelated with data acquired manually and a high order statistic software as well.

  15. Nonextensive dust acoustic waves in a charge varying dusty plasma

    Science.gov (United States)

    Bacha, Mustapha; Tribeche, Mouloud

    2012-01-01

    Our recent analysis on nonlinear nonextensive dust-acoustic waves (DA) [Amour and Tribeche in Phys. Plasmas 17:063702, 2010] is extended to include self-consistent nonadiabatic grain charge fluctuation. The appropriate nonextensive electron charging current is rederived based on the orbit-limited motion theory. Our results reveal that the amplitude, strength and nature of the nonlinear DA waves (solitons and shocks) are extremely sensitive to the degree of ion nonextensivity. Stronger is the electron correlation, more important is the charge variation induced nonlinear wave damping. The anomalous dissipation effects may prevail over that dispersion as the electrons evolve far away from their Maxwellian equilibrium. Our investigation may be of wide relevance to astronomers and space scientists working on interstellar dusty plasmas where nonthermal distributions are turning out to be a very common and characteristic feature.

  16. Geodesic acoustic modes excited by finite beta drift waves

    DEFF Research Database (Denmark)

    Chakrabarti, Nikhil Kumar; Guzdar, P.N.; Kleva, R.G.

    2008-01-01

    Presented in this paper is a mode-coupling analysis for the nonlinear excitation of the geodesic acoustic modes (GAMs) in tokamak plasmas by finite beta drift waves. The finite beta effects give rise to a strong stabilizing influence on the parametric excitation process. The dominant finite beta...... effect is the combination of the Maxwell stress, which has a tendency to cancel the primary drive from the Reynolds stress, and the finite beta modification of the drift waves. The zonal magnetic field is also excited at the GAM frequency. However, it does not contribute to the overall stability...... of the three-wave process for parameters of relevance to the edge region of tokamaks....

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

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  18. Landau damping in bi-dust ion-acoustic waves

    International Nuclear Information System (INIS)

    Castro, E.; Puerta, J.; Martin, P.; Cereceda, C.

    2006-01-01

    Ion acoustic dust waves in a bi-dust plasma are analyzed in this paper. In order to model this system, we assume the existence of two different kinds of grains, each characterized by a different radius. Relative velocities between grains and charge fluctuations are neglected. In order to derive the dispersion relation of this system, we use the well known hybrid fluid-kinetic model, in which ions are treated kinetically and other species as fluids. In this plasma, waves with non-relative velocities between species leads to damped waves with frequency modes, defined by the grain radius. The induced damping ratio is studied as a function of the grain and ion densities. (Author)

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

    KAUST Repository

    Xu, Jun

    2015-06-09

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

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

    Science.gov (United States)

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

    2015-06-09

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

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

    KAUST Repository

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

    2015-01-01

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

  2. 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

  3. Application of biorthogonal eigenfunction system for extraction of Tollmien-Schlichting waves in acoustic receptivity simulations

    OpenAIRE

    Shahriari, Nima; Hanifi, Ardeshir; Henningson, Dan S.

    2016-01-01

    Acoustic receptivity of a two-dimensional boundary layer on a flat plate with elliptic leading edge is studied through direct numerical simulation (DNS). Sound waves are modelled by a uniform oscillation of freestream boundaries in time which results to an infinite-wavelength acoustic wave. Acoustic disturbances interact with strong streamwise gradients at the leading edge or surface non- homogeneities and create Tollmien-Schlichting (TS) waves inside the boundary layer. Measuring amplitude o...

  4. Guided Acoustic and Optical Waves in Silicon-on-Insulator for Brillouin Scattering and Optomechanics

    Science.gov (United States)

    2016-08-01

    APL PHOTONICS 1, 071301 (2016) Guided acoustic and optical waves in silicon-on- insulator for Brillouin scattering and optomechanics Christopher J...is possible to simultaneously guide optical and acoustic waves in the technologically important silicon on insulator (SOI) material system. Thin...high sound velocity — makes guiding acoustic waves difficult, motivating the use of soft chalcogenide glasses and partial or complete releases (removal

  5. Paracousti-UQ: A Stochastic 3-D Acoustic Wave Propagation Algorithm.

    Energy Technology Data Exchange (ETDEWEB)

    Preston, Leiph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Acoustic full waveform algorithms, such as Paracousti, provide deterministic solutions in complex, 3-D variable environments. In reality, environmental and source characteristics are often only known in a statistical sense. Thus, to fully characterize the expected sound levels within an environment, this uncertainty in environmental and source factors should be incorporated into the acoustic simulations. Performing Monte Carlo (MC) simulations is one method of assessing this uncertainty, but it can quickly become computationally intractable for realistic problems. An alternative method, using the technique of stochastic partial differential equations (SPDE), allows computation of the statistical properties of output signals at a fraction of the computational cost of MC. Paracousti-UQ solves the SPDE system of 3-D acoustic wave propagation equations and provides estimates of the uncertainty of the output simulated wave field (e.g., amplitudes, waveforms) based on estimated probability distributions of the input medium and source parameters. This report describes the derivation of the stochastic partial differential equations, their implementation, and comparison of Paracousti-UQ results with MC simulations using simple models.

  6. Nonlinear ion-acoustic waves and solitons in a magnetized plasma

    International Nuclear Information System (INIS)

    Lee, L.C.; Kan, J.R.

    1981-01-01

    A unified formulation is presented to study the nonlinear low-frequency electrostatic waves in a magnetized low-β plasma. It is found that there exist three types of nonlinear waves; (1) nonlinear ion-cyclotron periodic waves with a wave speed V/sub p/ > C/sub s/ (ion-acoustic velocity); (2) nonlinear ion-acoustic periodic waves with V/sub p/ < C/sub s/ costheta; and (3) ion-acoustic solitons with C/sub s/ costheta < V/sub p/ < C/sub s/, where theta is the angle between the wave vector and the magnetic field

  7. The statistical mechanics of vortex-acoustic ion wave turbulence

    International Nuclear Information System (INIS)

    Giles, M.J.

    1980-01-01

    The equilibrium statistical mechanics of electrostatic ion wave turbulence is studied within the framework of a continuum ion flow with adiabatic electrons. The wave field consists in general of two components, namely ion-acoustic and ion vortex modes. It is shown that the latter can significantly affect the equilibria on account of their ability both to emit and to scatter ion sound. Exact equilibria for the vortex-acoustic wave field are given in terms of a canonical distribution and the correlation functions are expressed in terms of a generating functional. Detailed calculations are carried out for the case in which the dominant coupling is an indirect interaction of the vortex modes mediated by the sound field. An equation for the spectrum of the vortex modes is obtained for this case, which is shown to possess a simple exact solution. This solution shows that the spectrum of fluctuations changes considerably as the total energy increases. Condensed vortex states could occur in the plasma sheet of the earth's magnetosphere and it is shown that the predicted ratio of the mean ion energy to the mean electron energy is consistent with the trend of observed values. (author)

  8. Quantum corrections to nonlinear ion acoustic wave with Landau damping

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Abhik; Janaki, M. S. [Saha Institute of Nuclear Physics, Calcutta (India); Bose, Anirban [Serampore College, West Bengal (India)

    2014-07-15

    Quantum corrections to nonlinear ion acoustic wave with Landau damping have been computed using Wigner equation approach. The dynamical equation governing the time development of nonlinear ion acoustic wave with semiclassical quantum corrections is shown to have the form of higher KdV equation which has higher order nonlinear terms coming from quantum corrections, with the usual classical and quantum corrected Landau damping integral terms. The conservation of total number of ions is shown from the evolution equation. The decay rate of KdV solitary wave amplitude due to the presence of Landau damping terms has been calculated assuming the Landau damping parameter α{sub 1}=√(m{sub e}/m{sub i}) to be of the same order of the quantum parameter Q=ℏ{sup 2}/(24m{sup 2}c{sub s}{sup 2}L{sup 2}). The amplitude is shown to decay very slowly with time as determined by the quantum factor Q.

  9. 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...

  10. Collisionless damping of nonlinear dust ion acoustic wave due to dust charge fluctuation

    International Nuclear Information System (INIS)

    Ghosh, Samiran; Chaudhuri, Tushar K.; Sarkar, Susmita; Khan, Manoranjan; Gupta, M.R.

    2002-01-01

    A dissipation mechanism for the damping of the nonlinear dust ion acoustic wave in a collisionless dusty plasma consisting of nonthermal electrons, ions, and variable charge dust grains has been investigated. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust ion acoustic wave propagation to be described by the damped Korteweg-de Vries equation. Due to the presence of nonthermal electrons, the dust ion acoustic wave admits both positive and negative potential and it suffers less damping than the dust acoustic wave, which admits only negative potential

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

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Shiling; Shen, Zhonghua, E-mail: shenzh@njust.edu.cn [Faculty of Science, Nanjing University of Science and Technology, Nanjing 210094 (China); Lomonosov, Alexey M. [Faculty of Science, Nanjing University of Science and Technology, Nanjing 210094 (China); General Physics Institute, Russian Academy of Sciences, 119991 Moscow (Russian Federation)

    2016-06-07

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

  12. Application of gas-coupled laser acoustic detection to gelatins and underwater sensing

    International Nuclear Information System (INIS)

    Caron, James N.; Kunapareddy, Pratima

    2014-01-01

    Gas-coupled Laser Acoustic Detection (GCLAD) has been used as a method to sense ultrasound waves in materials without contact of the material surface. To sense the waveform, a laser beam is directed parallel to the material surface and displaced or deflected when the radiated waveform traverses the beam. We present recent tests that demonstrate the potential of using this technique for detecting ultrasound in gelatin phantoms and in water. As opposed to interferometric detection, GCLAD operates independently of the optical surface properties of the material. This allows the technique to be used in cases where the material is transparent or semi-transparent. We present results on sensing ultrasound in gelatin phantoms that are used to mimic biological materials. As with air-coupled transducers, the frequency response of GCLAD at high frequencies is limited by the high attenuation of ultrasound in air. In contrast, water has a much lower attenuation. Here we demonstrate the use of a GCLAD-like system in water, measuring the directivity response at 1 MHz and sensing waveforms with higher frequency content

  13. Radial wave crystals: radially periodic structures from anisotropic metamaterials for engineering acoustic or electromagnetic waves.

    Science.gov (United States)

    Torrent, Daniel; Sánchez-Dehesa, José

    2009-08-07

    We demonstrate that metamaterials with anisotropic properties can be used to develop a new class of periodic structures that has been named radial wave crystals. They can be sonic or photonic, and wave propagation along the radial directions is obtained through Bloch states like in usual sonic or photonic crystals. The band structure of the proposed structures can be tailored in a large amount to get exciting novel wave phenomena. For example, it is shown that acoustical cavities based on radial sonic crystals can be employed as passive devices for beam forming or dynamically orientated antennas for sound localization.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. An analysis of beam parameters on proton-acoustic waves through an analytic approach.

    Science.gov (United States)

    Kipergil, Esra Aytac; Erkol, Hakan; Kaya, Serhat; Gulsen, Gultekin; Unlu, Mehmet Burcin

    2017-06-21

    It has been reported that acoustic waves are generated when a high-energy pulsed proton beam is deposited in a small volume within tissue. One possible application of proton-induced acoustics is to get real-time feedback for intra-treatment adjustments by monitoring such acoustic waves. A high spatial resolution in ultrasound imaging may reduce proton range uncertainty. Thus, it is crucial to understand the dependence of the acoustic waves on the proton beam characteristics. In this manuscript, firstly, an analytic solution for the proton-induced acoustic wave is presented to reveal the dependence of the signal on the beam parameters; then it is combined with an analytic approximation of the Bragg curve. The influence of the beam energy, pulse duration and beam diameter variation on the acoustic waveform are investigated. Further analysis is performed regarding the Fourier decomposition of the proton-acoustic signals. Our results show that the smaller spill time of the proton beam upsurges the amplitude of the acoustic wave for a constant number of protons, which is hence beneficial for dose monitoring. The increase in the energy of each individual proton in the beam leads to the spatial broadening of the Bragg curve, which also yields acoustic waves of greater amplitude. The pulse duration and the beam width of the proton beam do not affect the central frequency of the acoustic wave, but they change the amplitude of the spectral components.

  19. Towards the Wetness Characterization of Soil Subsurface Using Fibre Optic Distributed Acoustic Sensing

    Science.gov (United States)

    Ciocca, F.; Bodet, L.; Simon, N.; Karaulanov, R.; Clarke, A.; Abesser, C.; Krause, S.; Chalari, A.; Mondanos, M.

    2017-12-01

    Active seismic methods combined with detectors deployed at the soil surface, such as vertical collinear geophones, have revealed great potential for hydrogeophysical characterization of the soil vadose zone. In particular, recent findings have highlighted a clear dependence of both P-waves arrival times and surface-wave dispersion on the local degree of soil saturation, visible at laboratory as well as at field scale. In this study, we investigate the sensitivity of a fibre optic Distributed Acoustic Sensor (DAS) to different soil saturation. In vertical seismic applications, DAS have proven to offer equal and often better performance compared to the geophones, with the advantage that a fibre optic cable, whose length can reach 40 km, replaces the array of geophones as sensing element. We present the response to active seismic tests of 20 m of fibre optic cable buried in a poorly permeable bare soil. Tests were conducted in different moments of the year, with saturation monitored by means of independent dielectric probes. Body-wave travel times as well as surface-wave dispersion are compared. Finally, we discuss the possibility to determine a site-specific relation between the Poisson ratio and the soil saturation. This research has been performed in the framework of the British National Environmental Research Council (NERC) funded Distributed intelligent Heat Pulse System (DiHPS) project and of the Marie Curie H2020 Research and Innovation Staff Exchange (RISE) consortium Hi-Freq.

  20. Nonlinear Electron Acoustic Waves in Dissipative Plasma with Superthermal Electrons

    Science.gov (United States)

    El-Hanbaly, A. M.; El-Shewy, E. K.; Kassem, A. I.; Darweesh, H. F.

    2016-01-01

    The nonlinear properties of small amplitude electron-acoustic ( EA) solitary and shock waves in a homogeneous system of unmagnetized collisionless plasma consisted of a cold electron fluid and superthermal hot electrons obeying superthermal distribution, and stationary ions have been investigated. A reductive perturbation method was employed to obtain the Kadomstev-Petviashvili-Burgers (KP-Brugers) equation. Some solutions of physical interest are obtained. These solutions are related to soliton, monotonic and oscillatory shock waves and their behaviour are shown graphically. The formation of these solutions depends crucially on the value of the Burgers term and the plasma parameters as well. By using the tangent hyperbolic (tanh) method, another interesting type of solution which is a combination between shock and soliton waves is obtained. The topology of phase portrait and potential diagram of the KP-Brugers equation is investigated.The advantage of using this method is that one can predict different classes of the travelling wave solutions according to different phase orbits. The obtained results may be helpful in better understanding of waves propagation in various space plasma environments as well as in inertial confinement fusion laboratory plasmas.

  1. Acoustic-gravity waves in atmospheric and oceanic waveguides.

    Science.gov (United States)

    Godin, Oleg A

    2012-08-01

    A theory of guided propagation of sound in layered, moving fluids is extended to include acoustic-gravity waves (AGWs) in waveguides with piecewise continuous parameters. The orthogonality of AGW normal modes is established in moving and motionless media. A perturbation theory is developed to quantify the relative significance of the gravity and fluid compressibility as well as sensitivity of the normal modes to variations in sound speed, flow velocity, and density profiles and in boundary conditions. Phase and group speeds of the normal modes are found to have certain universal properties which are valid for waveguides with arbitrary stratification. The Lamb wave is shown to be the only AGW normal mode that can propagate without dispersion in a layered medium.

  2. 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.

  3. Arbitrary electron acoustic waves in degenerate dense plasmas

    Science.gov (United States)

    Rahman, Ata-ur; Mushtaq, A.; Qamar, A.; Neelam, S.

    2017-05-01

    A theoretical investigation is carried out of the nonlinear dynamics of electron-acoustic waves in a collisionless and unmagnetized plasma whose constituents are non-degenerate cold electrons, ultra-relativistic degenerate electrons, and stationary ions. A dispersion relation is derived for linear EAWs. An energy integral equation involving the Sagdeev potential is derived, and basic properties of the large amplitude solitary structures are investigated in such a degenerate dense plasma. It is shown that only negative large amplitude EA solitary waves can exist in such a plasma system. The present analysis may be important to understand the collective interactions in degenerate dense plasmas, occurring in dense astrophysical environments as well as in laser-solid density plasma interaction experiments.

  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. 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.

  6. Acoustic wave filter based on periodically poled lithium niobate.

    Science.gov (United States)

    Courjon, Emilie; Bassignot, Florent; Ulliac, Gwenn; Benchabane, Sarah; Ballandras, Sylvain

    2012-09-01

    Solutions for the development of compact RF passive transducers as an alternative to standard surface or bulk acoustic wave devices are receiving increasing interest. This article presents results on the development of an acoustic band-pass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of periodically poled transducers (PPTs) operating in the range of 20 to 650 MHz has been achieved on 3-in (76.2-mm) 500-μm-thick wafers. This kind of transducer is able to excite elliptical as well as longitudinal modes, yielding phase velocities of about 3800 and 6500 ms(-1), respectively. A new type of acoustic band-pass filter is proposed, based on the use of PPTs instead of the SAWs excited by classical interdigital transducers. The design and the fabrication of such a filter are presented, as well as experimental measurements of its electrical response and transfer function. The feasibility of such a PPT-based filter is thereby demonstrated and the limitations of this method are discussed.

  7. Visco-acoustic wave-equation traveltime inversion and its sensitivity to attenuation errors

    KAUST Repository

    Yu, Han; Chen, Yuqing; Hanafy, Sherif M.; Huang, Jiangping

    2018-01-01

    A visco-acoustic wave-equation traveltime inversion method is presented that inverts for the shallow subsurface velocity distribution. Similar to the classical wave equation traveltime inversion, this method finds the velocity model that minimizes

  8. Positron-acoustic waves in an electron-positron plasma with an electron beam

    International Nuclear Information System (INIS)

    Nejoh, Y.N.

    1996-01-01

    The nonlinear wave structures of large-amplitude positron-acoustic waves are studied in an electron-positron plasma in the presence of an electron beam with finite temperature and hot electrons and positrons. The region where positron-acoustic waves exist is presented by analysing the structure of the pseudopotential. The region depends sensitively on the positron density, the positron temperature and the electron beam temperature. It is shown that the maximum amplitude of the wave decreases as the positron temperature increases, and the region of positron-acoustic waves spreads as the positron temperature increases. 11 refs., 5 figs

  9. Nucleus-acoustic shock waves in white dwarfs

    Science.gov (United States)

    Jannat, S.; Mamun, A. A.

    2018-04-01

    The nucleus-acoustic shock waves (NASWs) propagating in a white dwarf plasma system, which contain non-relativistically or ultrarelativistically degenerate electrons, non-relativistically degenerate, viscous fluid of light nuclei, and immobile nuclei of heavy elements, have been theoretically investigated. We have used the reductive perturbation method, which is valid for small but finite-amplitude NASWs to derive the Burgers equation. The NASWs are, in fact, associated with the nucleus-acoustic (NA) waves in which the inertia is provided by the light nuclei, and restoring force is provided by the degenerate pressure of electrons. On the other hand, the stationary heavy nuclei participate only in maintaining the background charge neutrality condition at equilibrium. It is found that the viscous force acting in the fluid of light nuclei is a source of dissipation, and is responsible for the formation of NASWs. It is also observed that the basic features (polarity, amplitude, width, etc.) of the NASWs are significantly modified by the presence of heavy nuclei, and that NASWs are formed with either positive or negative potential depending on the values of the charge density of the heavy nuclei. The basic properties are also found to be significantly modified by the effects of ultrarelativistically degenerate electrons. The implications of our results in white dwarfs are briefly discussed.

  10. Dust acoustic waves in complex plasmas at elevated pressure

    International Nuclear Information System (INIS)

    Filippov, A.V.; Starostin, A.N.; Tkachenko, I.M.; Fortov, V.E.

    2011-01-01

    The bi-Yukawa effective interaction potential with different screening constants is employed to calculate dust static correlation functions in the hyper-netted chain approximation and to generalize the theory of dust acoustic waves within the non-perturbative moment approach complemented by hydrodynamic considerations. For the bi-Yukawa interaction potential the sound speed becomes significantly wavenumber-dependent, an additional soft diffusion-like mode is predicted, and the static dielectric function is shown to take negative values. The results can be applied to non-equilibrium dusty plasmas at elevated pressure. -- Highlights: ► Bi-Yukawa interaction potential of dust particles with different screening lengths. ► Dust static correlation functions in the hyper-netted chain approximation. ► The moment and hydrodynamic approaches are in a good agreement at weak non-ideality. ► The dust acoustic wave phase and group velocities depend on the wavenumber. ► The moment approach hints the appearance of the diffusion-like soft mode.

  11. 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)

  12. Nonlinear mechanisms of two-dimensional wave-wave transformations in the initially coupled acoustic structure

    Science.gov (United States)

    Vorotnikov, K.; Starosvetsky, Y.

    2018-01-01

    The present study concerns two-dimensional nonlinear mechanisms of bidirectional and unidirectional channeling of longitudinal and shear waves emerging in the locally resonant acoustic structure. The system under consideration comprises an oscillatory chain of the axially coupled masses. Each mass of the chain is subject to the local linear potential along the lateral direction and incorporates the lightweight internal rotator. In the present work, we demonstrate the emergence of special resonant regimes of complete bi- and unidirectional transitions between the longitudinal and the shear waves of the locally resonant chain. These regimes are manifested by the two-dimensional energy channeling between the longitudinal and the shear traveling waves in the recurrent as well as the irreversible fashion. We show that the spatial control of the two dimensional energy flow between the longitudinal and the shear waves is solely governed by the motion of the internal rotators. Nonlinear analysis of the regimes of a bidirectional wave channeling unveils their global bifurcation structure and predicts the zones of their spontaneous transitions from a complete bi-directional wave channeling to the one-directional entrapment. An additional regime of a complete irreversible resonant transformation of the longitudinal wave into a shear wave is analyzed in the study. The intrinsic mechanism governing the unidirectional wave reorientation is described analytically. The results of the analysis of both mechanisms are substantiated by the numerical simulations of the full model and are found to be in a good agreement.

  13. Damping-Growth Transition for Ion-Acoustic Waves in a Density Gradient

    DEFF Research Database (Denmark)

    D'Angelo, N.; Michelsen, Poul; Pécseli, Hans

    1975-01-01

    A damping-growth transition for ion-acoustic waves propagating in a nonuniform plasma (e-folding length for the density ln) is observed at a wavelength λ∼2πln. This result supports calculations performed in connection with the problem of heating of the solar corona by ion-acoustic waves generated...

  14. Iterative calculation of reflected and transmitted acoustic waves at a rough interface

    NARCIS (Netherlands)

    Berkhoff, Arthur P.; van den Berg, P.M.; Thijssen, J.M.

    A rigorous iterative technique is described for calculating the acoustic wave reflection and transmission at an irregular interface between two different media. The method is based upon a plane-wave expansion technique in which the acoustic field equations and the radiation condition are satisfied

  15. 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.

  16. Acoustic waves in transversely excited atmospheric CO2 laser discharges: effect on performance and reduction techniques

    CSIR Research Space (South Africa)

    von Bergmann, HM

    2008-08-01

    Full Text Available Results are presented on the influence of acoustic waves on the performance of high-repetition-rate TEA CO2 lasers. It is shown that acoustic waves generated inside the laser cavity lead to nonuniform discharges, resulting in a deterioration...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

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

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

    International Nuclear Information System (INIS)

    Peratt, A.L.; Watterson, R.L.; Derfler, H.

    1977-01-01

    Scattering of laser radiation from ion-acoustic waves in a plasma is investigated analytically and experimentally. The formulation predicts a coherent component of the scattered power on a largely incoherent background spectrum when the acoustic analog of Bragg's law and Doppler shift conditions are satisfied. The experiment consists of a hybrid CO 2 laser system capable of either low power continuous wave or high power pulsed mode operation. A heterodyne light mixing scheme is used to detect the scattered power. The proportionality predicted by the theory is verified by scattering from externally excited acoustic and ion-acoustic waves; continuous wave and pulsed modes in each case. Measurement of the ion-acoustic dispersion relation by continuous wave scattering is also presented

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

    KAUST Repository

    Zhan, Ge; Pestana, Reynam C.; Stoffa, Paul L.

    2011-01-01

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

  20. On-Chip Production of Size-Controllable Liquid Metal Microdroplets Using Acoustic Waves.

    Science.gov (United States)

    Tang, Shi-Yang; Ayan, Bugra; Nama, Nitesh; Bian, Yusheng; Lata, James P; Guo, Xiasheng; Huang, Tony Jun

    2016-07-01

    Micro- to nanosized droplets of liquid metals, such as eutectic gallium indium (EGaIn) and Galinstan, have been used for developing a variety of applications in flexible electronics, sensors, catalysts, and drug delivery systems. Currently used methods for producing micro- to nanosized droplets of such liquid metals possess one or several drawbacks, including the lack in ability to control the size of the produced droplets, mass produce droplets, produce smaller droplet sizes, and miniaturize the system. Here, a novel method is introduced using acoustic wave-induced forces for on-chip production of EGaIn liquid-metal microdroplets with controllable size. The size distribution of liquid metal microdroplets is tuned by controlling the interfacial tension of the metal using either electrochemistry or electrocapillarity in the acoustic field. The developed platform is then used for heavy metal ion detection utilizing the produced liquid metal microdroplets as the working electrode. It is also demonstrated that a significant enhancement of the sensing performance is achieved by introducing acoustic streaming during the electrochemical experiments. The demonstrated technique can be used for developing liquid-metal-based systems for a wide range of applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Underwater Acoustic Matched Field Imaging Based on Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Huichen Yan

    2015-10-01

    Full Text Available Matched field processing (MFP is an effective method for underwater target imaging and localizing, but its performance is not guaranteed due to the nonuniqueness and instability problems caused by the underdetermined essence of MFP. By exploiting the sparsity of the targets in an imaging area, this paper proposes a compressive sensing MFP (CS-MFP model from wave propagation theory by using randomly deployed sensors. In addition, the model’s recovery performance is investigated by exploring the lower bounds of the coherence parameter of the CS dictionary. Furthermore, this paper analyzes the robustness of CS-MFP with respect to the displacement of the sensors. Subsequently, a coherence-excluding coherence optimized orthogonal matching pursuit (CCOOMP algorithm is proposed to overcome the high coherent dictionary problem in special cases. Finally, some numerical experiments are provided to demonstrate the effectiveness of the proposed CS-MFP method.

  2. Stimulated scattering of space-charge waves in a relativistic electron beam by the ion acoustic wave of a plasma waveguide

    International Nuclear Information System (INIS)

    Balakirev, V.A.; Buts, V.A.

    1982-01-01

    The interaction of a relativistic electron beam with a plasma waveguide whose density is modulated by an ion acoustic wave leads to the emission of electromagnetic radiation. The wavelength of the radiation is 2#betta# 2 times shorter than the ion acoustic wavelength. The emission is accompanied by the amplification of the ion acoustic wave. The maximum amplitudes of the excited waves are found

  3. Thermal Cracking in Westerly Granite Monitored Using Direct Wave Velocity, Coda Wave Interferometry, and Acoustic Emissions

    Science.gov (United States)

    Griffiths, L.; Lengliné, O.; Heap, M. J.; Baud, P.; Schmittbuhl, J.

    2018-03-01

    To monitor both the permanent (thermal microcracking) and the nonpermanent (thermo-elastic) effects of temperature on Westerly Granite, we combine acoustic emission monitoring and ultrasonic velocity measurements at ambient pressure during three heating and cooling cycles to a maximum temperature of 450°C. For the velocity measurements we use both P wave direct traveltime and coda wave interferometry techniques, the latter being more sensitive to changes in S wave velocity. During the first cycle, we observe a high acoustic emission rate and large—and mostly permanent—apparent reductions in velocity with temperature (P wave velocity is reduced by 50% of the initial value at 450°C, and 40% upon cooling). Our measurements are indicative of extensive thermal microcracking during the first cycle, predominantly during the heating phase. During the second cycle we observe further—but reduced—microcracking, and less still during the third cycle, where the apparent decrease in velocity with temperature is near reversible (at 450°C, the P wave velocity is decreased by roughly 10% of the initial velocity). Our results, relevant for thermally dynamic environments such as geothermal reservoirs, highlight the value of performing measurements of rock properties under in situ temperature conditions.

  4. 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.

  5. 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.

  6. Acoustic Wave Treatment For Cellulite—A New Approach

    Science.gov (United States)

    Russe-Wilflingseder, Katharina; Russe, Elisabeth

    2010-05-01

    Background and Objectives: Cellulite is a biological caused modification of the female connective tissue. In extracorporeal shockwave therapy (ESWT) pulses are penetrating into the tissue without causing a thermal effect or micro lesions, but leading to a stimulation of tissue metabolism and blood circulation, inducing a natural repair process with cell activation and stem cells proliferation. Recently ESWT treatment showed evidence of remodelling collagen within the dermis and of stimulating microcirculation in fatty tissue. Study Design and Methods: The study was designed to assess acoustic wave treatment for cellulite by comparison treated vs. untreated side (upper-leg and buttock). Each individual served as its own control. 11 females with a BMI less then 30 and an age over 18 years were included. 6 treatments were given weekly with radial acoustic waves. Documentation was done before and 1, 4, 12 weeks after last treatment by standardized photo documentation, relaxed and with muscle contraction, measurement of body weight and circumference of the thigh, pinch test, and evaluation of hormonal status and lifestyle. The efficacy of AWT/EPAT was evaluated before and 1, 4, 12 weeks after last treatment. Patients rated the improvement of cellulite, overall satisfaction and acceptance. The therapist assessed improvement of cellulite, side effects and photo documentation treated vs. untreated side, before vs. after treatment. The blinded investigator evaluated the results using photo documentation right vs. left leg, before vs. after treatment in a frontal, lateral and dorsal view, relaxed and with muscle contraction. Results: The improvement of cellulite at the treated side was rated by patients with 27,3% at week 4 and 12, by the therapist with 34,1% at week 4 and 31,2% at week 12 after the last treatment The blinded investigator could verify an improvement of cellulite in an increasing number of patients with increasing time interval after treatment. No side

  7. 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

  8. Ultrasonic phased array with surface acoustic wave for imaging cracks

    Directory of Open Access Journals (Sweden)

    Yoshikazu Ohara

    2017-06-01

    Full Text Available To accurately measure crack lengths, we developed a real-time surface imaging method (SAW PA combining an ultrasonic phased array (PA with a surface acoustic wave (SAW. SAW PA using a Rayleigh wave with a high sensitivity to surface defects was implemented for contact testing using a wedge with the third critical angle that allows the Rayleigh wave to be generated. Here, to realize high sensitivity imaging, SAW PA was optimized in terms of the wedge and the imaging area. The improved SAW PA was experimentally demonstrated using a fatigue crack specimen made of an aluminum alloy. For further verification in more realistic specimens, SAW PA was applied to stainless-steel specimens with a fatigue crack and stress corrosion cracks (SCCs. The fatigue crack was visualized with a high signal-to-noise ratio (SNR and its length was measured with a high accuracy of better than 1 mm. The SCCs generated in the heat-affected zones (HAZs of a weld were successfully visualized with a satisfactory SNR, although responses at coarse grains appeared throughout the imaging area. The SCC lengths were accurately measured. The imaging results also precisely showed complicated distributions of SCCs, which were in excellent agreement with the optically observed distributions.

  9. Dynamics of beam-driven Langmuir and ion-acoustic waves including electrostatic decay

    International Nuclear Information System (INIS)

    Li, B.; Willes, A.J.; Robinson, P.A.; Cairns, I.H.

    2003-01-01

    The evolution of Langmuir waves and ion-acoustic waves stimulated by a hot electron beam in an initially homogeneous plasma is investigated numerically in time, position, and wave number space. Quasilinear interactions between the beam particles and Langmuir waves, nonlinear interactions between the Langmuir and ion-acoustic waves through Langmuir decay processes, and spontaneous emission are taken into account in the kinetic theory employed. For illustrative parameters of those in the solar wind near 1 a.u., nonlinear Langmuir decays are observed to transfer the beam-driven Langmuir waves rapidly out of resonance. The scattered Langmuir waves then undergo further decays, moving sequentially toward small wave numbers, until decay is kinematically prohibited. The main features of the evolution of Langmuir and ion-acoustic waves are spatially inhomogeneous. The scattered Langmuir spectra increase and eventually reach or exceed the beam-driven Langmuir spectra at a given spatial location (except in regions where further decays proceed). The ion-acoustic waves are relatively weak and subject to damping at the later stages of their evolution. The development of fine structures in the product Langmuir and ion-acoustic waves are observed, due to depletion of their energy by decay and dominant damping effects, respectively. The propagation of the beam is essentially unaffected by the operation of the decay process. The decay process is thus slaved to the primary beam-plasma evolution, as assumed in previous studies. A variation of the ratio of electron temperature to ion temperature is found to affect not only the ion-acoustic wave levels through effects on the damping rate, but also the dynamics of decay via effects on the decay rate. The latter was not addressed in previous studies. Furthermore, spontaneous emission of ion-acoustic waves is found to affect the dynamics of decay, thus its inclusion is necessary to correctly model the Langmuir and ion-acoustic spectra

  10. 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.

  11. 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

  12. STATISTICAL ANALYSIS OF ACOUSTIC WAVE PARAMETERS NEAR SOLAR ACTIVE REGIONS

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  13. 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.

  14. Ray and wave chaos in underwater acoustic waveguides

    International Nuclear Information System (INIS)

    Virovlyansky, Anatolii L; Makarov, Denis V; Prants, Sergei V

    2012-01-01

    In the 1990s, the study of the chaotic behavior of ray trajectories in inhomogeneous waveguides emerged as a new field in ocean acoustics. It turned out that at ranges on the order of or larger than 1000 km ray chaos is well developed and should be taken into account when describing long-range sound propagation in the ocean. The theoretical analysis of ray chaos and of its finite-wavelength manifestation, wave chaos, is to a large extent based on well-known methods and ideas from the theory of dynamical and quantum chaos. Concrete examples are used to review the results obtained in this field over the last two decades. (reviews of topical problems)

  15. A Comparison of Surface Acoustic Wave Modeling Methods

    Science.gov (United States)

    Wilson, W. c.; Atkinson, G. M.

    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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Making Sense of How Students Make Sense of Mechanical Waves

    OpenAIRE

    Wittmann, Michael C.; Steinberg, Richard N.; Redish, Edward F.

    2002-01-01

    We report on our study of student understanding of the physics of mechanical waves, specifically the propagation and superposition of simple wavepulses traveling on long, taut strings. We introduce the terms "particle pulses mental model" to describe the reasoning approach that students use to guide their thinking in wave propagation and superposition. Student responses on free response and multiple-choice, multiple response questions dealing with the same physics show inconsistent student th...

  1. Oblique Modulation of Ion-Acoustic Waves in a Warm Plasma

    International Nuclear Information System (INIS)

    Xue Jukui; Tang Rongan

    2003-01-01

    The stability of oblique modulation of ion-acoustic waves in an unmagnetized warm plasma is studied. A nonlinear Schroedinger equation governing the slow modulation of the wave amplitude is derived. The effect of temperature on the oblique modulational instability of the ion-acoustic wave is investigated. It is found that the ion temperature significantly changes the domain of the modulational instability in the k-θ plane

  2. Effect of finite ion-temperature on ion-acoustic solitary waves in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    Shivamoggi, B.K.

    1981-01-01

    The propagation of weakly nonlinear ion-acoustic waves in an inhomogeneous plasma is studied taking into account the effect of finite ion temperature. It is found that, whereas both the amplitude and the velocity of propagation decrease as the ion-acoustic solitary wave propagates into regions of higher density, the effect of a finite ion temperature is to reduce the amplitude but enhance the velocity of propagation of the solitary wave. (author)

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

    International Nuclear Information System (INIS)

    Tsytovich, V.N.; Watanabe, K.

    2002-01-01

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

  4. JOINT RIGIDITY ASSESSMENT WITH PIEZOELECTRIC WAFERS AND ACOUSTIC WAVES

    International Nuclear Information System (INIS)

    Montoya, Angela C.; Maji, Arup K.

    2010-01-01

    There has been an interest in the development of rapid deployment satellites. In a modular satellite design, different panels of specific functions can be pre-manufactured. The satellite can then be assembled and tested just prior to deployment. Traditional vibration testing is time-consuming and expensive. An alternative test method to evaluate the connection between two plates will be proposed. The method investigated and described employs piezoelectric wafers to induce and sense lamb waves in two aluminum plates, which were joined by steel brackets to form an 'L-Style' joint. Lamb wave behavior and piezoelectric material properties will be discussed; the experimental setup and results will be presented. A set of 4 piezoelectric ceramic wafers were used alternately as source and sensor. The energy transmitted was shown to correlate with a mechanical assessment of the joint, demonstrating that this method of testing is a feasible and reliable way to inspect the rigidity of joints.

  5. Ion-acoustic nonlinear periodic waves in electron-positron-ion plasma

    International Nuclear Information System (INIS)

    Chawla, J. K.; Mishra, M. K.

    2010-01-01

    Ion-acoustic nonlinear periodic waves, namely, ion-acoustic cnoidal waves have been studied in electron-positron-ion plasma. Using reductive perturbation method and appropriate boundary condition for nonlinear periodic waves, the Korteweg-de Vries (KdV) equation is derived for the system. The cnoidal wave solution of the KdV equation is discussed in detail. It is found that the frequency of the cnoidal wave is a function of its amplitude. It is also found that the positron concentration modifies the properties of the ion-acoustic cnoidal waves. The existence regions for ion-acoustic cnoidal wave in the parameters space (p,σ), where p and σ are the positron concentration and temperature ratio of electron to positron, are discussed in detail. In the limiting case these ion-acoustic cnoidal waves reduce to the ion-acoustic soliton solutions. The effect of other parameters on the characteristics of the nonlinear periodic waves is also discussed.

  6. Acoustic wave emission for enhanced oil recovery (WAVE.O.R.)

    Energy Technology Data Exchange (ETDEWEB)

    Reichmann, S.; Amro, M. [TU Bergakademie, Freiberg (Germany); Giese, R.; Jaksch, K.; Krauss, F.; Krueger, K.; Jurczyk, A. [Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ, Potsdam (Germany)

    2016-09-15

    In the project WAVE.O.R the potential of acoustic waves to enhance oil recovery was reviewed. The project focused on laboratory experiments of the oil displacement in sandstone cores under acoustic stimulation. Additionally, the Seismic Prediction While Drilling (SPWD) borehole device prototype was set up for a feasibility field test. The laboratory experiments showed that, depending on the stimulation frequency, acoustic stimulation allows for an enhanced oil recovery. For single frequency stimulation a mean increase of 3 % pore volumes was observed at distinguished frequencies. A cyclic stimulation, where two of these frequencies were combined, an increase of 5% pore volume was observed. The SPWD borehole device was tested and adjusted during feasibility tests in the GFZ underground laboratory in the research and education mine ''Reiche Zeche'' of the TU Bergakademie Freiberg and in the GFZ KTB-Deep Laboratory in Windischeschenbach. The first successful test of the device under realistic conditions was performed at the test site ''Piana di Toppo'' of the OGS Trieste, Italy.

  7. Acoustic wave emission for enhanced oil recovery (WAVE.O.R.)

    International Nuclear Information System (INIS)

    Reichmann, S.; Amro, M.; Giese, R.; Jaksch, K.; Krauss, F.; Krueger, K.; Jurczyk, A.

    2016-09-01

    In the project WAVE.O.R the potential of acoustic waves to enhance oil recovery was reviewed. The project focused on laboratory experiments of the oil displacement in sandstone cores under acoustic stimulation. Additionally, the Seismic Prediction While Drilling (SPWD) borehole device prototype was set up for a feasibility field test. The laboratory experiments showed that, depending on the stimulation frequency, acoustic stimulation allows for an enhanced oil recovery. For single frequency stimulation a mean increase of 3 % pore volumes was observed at distinguished frequencies. A cyclic stimulation, where two of these frequencies were combined, an increase of 5% pore volume was observed. The SPWD borehole device was tested and adjusted during feasibility tests in the GFZ underground laboratory in the research and education mine ''Reiche Zeche'' of the TU Bergakademie Freiberg and in the GFZ KTB-Deep Laboratory in Windischeschenbach. The first successful test of the device under realistic conditions was performed at the test site ''Piana di Toppo'' of the OGS Trieste, Italy.

  8. Integration of thin film giant magnetoimpedance sensor and surface acoustic wave transponder

    KAUST Repository

    Li, Bodong

    2012-03-09

    Passive and remote sensing technology has many potential applications in implantable devices, automation, or structural monitoring. In this paper, a tri-layer thin film giant magnetoimpedance (GMI) sensor with the maximum sensitivity of 16%/Oe and GMI ratio of 44% was combined with a two-port surface acoustic wave(SAW) transponder on a common substrate using standard microfabrication technology resulting in a fully integrated sensor for passive and remote operation. The implementation of the two devices has been optimized by on-chip matching circuits. The measurement results clearly show a magnetic field response at the input port of the SAW transponder that reflects the impedance change of the GMI sensor.

  9. Integration of thin film giant magnetoimpedance sensor and surface acoustic wave transponder

    KAUST Repository

    Li, Bodong; Salem, Nedime Pelin M. H.; Giouroudi, Ioanna; Kosel, Jü rgen

    2012-01-01

    Passive and remote sensing technology has many potential applications in implantable devices, automation, or structural monitoring. In this paper, a tri-layer thin film giant magnetoimpedance (GMI) sensor with the maximum sensitivity of 16%/Oe and GMI ratio of 44% was combined with a two-port surface acoustic wave(SAW) transponder on a common substrate using standard microfabrication technology resulting in a fully integrated sensor for passive and remote operation. The implementation of the two devices has been optimized by on-chip matching circuits. The measurement results clearly show a magnetic field response at the input port of the SAW transponder that reflects the impedance change of the GMI sensor.

  10. Landau damping of dust acoustic solitary waves in nonthermal plasmas

    Science.gov (United States)

    Ghai, Yashika; Saini, N. S.; Eliasson, B.

    2018-01-01

    Dust acoustic (DA) solitary and shock structures have been investigated under the influence of Landau damping in a dusty plasma containing two temperature nonthermal ions. Motivated by the observations of Geotail spacecraft that reported two-temperature ion population in the Earth's magnetosphere, we have investigated the effect of resonant wave-particle interactions on DA nonlinear structures. The Korteweg-de Vries (KdV) equation with an additional Landau damping term is derived and its analytical solution is presented. The solution has the form of a soliton whose amplitude decreases with time. Further, we have illustrated the influence of Landau damping and nonthermality of the ions on DA shock structures by a numerical solution of the Landau damping modified KdV equation. The study of the time evolution of shock waves suggests that an initial shock-like pulse forms an oscillatory shock at later times due to the balance of nonlinearity, dispersion, and dissipation due to Landau damping. The findings of the present investigation may be useful in understanding the properties of nonlinear structures in the presence of Landau damping in dusty plasmas containing two temperature ions obeying nonthermal distribution such as in the Earth's magnetotail.

  11. 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.

  12. 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.

  13. 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...

  14. 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

  15. Reflection and absorption of ion-acoustic waves in a plasma density gradient

    International Nuclear Information System (INIS)

    Ishihara, O.

    1977-01-01

    Plasma is characterized by electrical quasineutrality and the collective behavior. There exists a longitudinal low-frequency wave called an ion-acoustic wave in a plasma. One problem in the experimental study of ion-acoustic waves has been that sometimes they are observed to be reflected from discharge tube walls, and sometimes to be absorbed. Theoretical computation reveals that a velocity gradient produced by a density gradient plays a significant role in the reflection. The velocity gradient produces the subsonic-supersonic transition and long wavelength waves are reflected before reaching the transition while short wavelength waves penetrate over the transition and are absorbed in the supersonic flow plasma

  16. Time-resolved measurement of global synchronization in the dust acoustic wave

    Science.gov (United States)

    Williams, J. D.

    2014-10-01

    A spatially and temporally resolved measurement of the synchronization of the naturally occurring dust acoustic wave to an external drive and the relaxation from the driven wave mode back to the naturally occuring wave mode is presented. This measurement provides a time-resolved measurement of the synchronization of the self-excited dust acoustic wave with an external drive and the return to the self-excited mode. It is observed that the wave synchronizes to the external drive in a distinct time-dependent fashion, while there is an immediate loss of synchronization when the external modulation is discontinued.

  17. Attenuation compensation in least-squares reverse time migration using the visco-acoustic wave equation

    KAUST Repository

    Dutta, Gaurav

    2013-08-20

    Attenuation leads to distortion of amplitude and phase of seismic waves propagating inside the earth. Conventional acoustic and least-squares reverse time migration do not account for this distortion which leads to defocusing of migration images in highly attenuative geological environments. To account for this distortion, we propose to use the visco-acoustic wave equation for least-squares reverse time migration. Numerical tests on synthetic data show that least-squares reverse time migration with the visco-acoustic wave equation corrects for this distortion and produces images with better balanced amplitudes compared to the conventional approach. © 2013 SEG.

  18. 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...

  19. Effects of ion acoustic waves on diffusion in a magnetized plasma

    International Nuclear Information System (INIS)

    Watanabe, Yukio; Akazaki, Masanori; Fujiyama, Hiroshi.

    1975-01-01

    This paper describes on the behavior of ion acoustic waves in magnetized plasma. The plasma was produced with a discharge tube placed in an air-core coil. The pressure of argon gas in the discharge tube was 1--10 mTorr. The plasma was entracted along the externally applied magnetic field through a nozzle into a measuring part. The condition of stabilization of drift waves was investigated. Four small glass tubes were placed in contact with the wall of the discharge tube, and the drift wave was remarkably suppressed. Then the ion acoustic waves can be observed. The magnetic field dependence of the frequency of ion acoustic waves was studied. The frequency depends on magnetic field and gas pressure. The magnetic field dependence of the frequency is caused by the variation of electron temperature. The Timofee's theory can explain the magnetic field of generating ion acoustic waves. The ion acoustic waves being excited naturally propagate to the direction of the diamagnetic drift of electrons, and their spectra are monochromatic. The dependence of Dsub(perpendicular), diffusion constant, on magnetic field is explained by two-pole diffusion, and the effect of the monochromatic ion acoustic waves on diffusion is small. (Kato, T.)

  20. 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

  1. Acoustic multipath arrivals in the horizontal plane due to approaching nonlinear internal waves.

    Science.gov (United States)

    Badiey, Mohsen; Katsnelson, Boris G; Lin, Ying-Tsong; Lynch, James F

    2011-04-01

    Simultaneous measurements of acoustic wave transmissions and a nonlinear internal wave packet approaching an along-shelf acoustic path during the Shallow Water 2006 experiment are reported. The incoming internal wave packet acts as a moving frontal layer reflecting (or refracting) sound in the horizontal plane. Received acoustic signals are filtered into acoustic normal mode arrivals. It is shown that a horizontal multipath interference is produced. This has previously been called a horizontal Lloyd's mirror. The interference between the direct path and the refracted path depends on the mode number and frequency of the acoustic signal. A mechanism for the multipath interference is shown. Preliminary modeling results of this dynamic interaction using vertical modes and horizontal parabolic equation models are in good agreement with the observed data.

  2. 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.

  3. Structural sensing of interior sound for active control of noise in structural-acoustic cavities.

    Science.gov (United States)

    Bagha, Ashok K; Modak, S V

    2015-07-01

    This paper proposes a method for structural sensing of acoustic potential energy for active control of noise in a structural-acoustic cavity. The sensing strategy aims at global control and works with a fewer number of sensors. It is based on the established concept of radiation modes and hence does not add too many states to the order of the system. Acoustic potential energy is sensed using a combination of a Kalman filter and a frequency weighting filter with the structural response measurements as the inputs. The use of Kalman filter also makes the system robust against measurement noise. The formulation of the strategy is presented using finite element models of the system including that of sensors and actuators so that it can be easily applied to practical systems. The sensing strategy is numerically evaluated in the framework of Linear Quadratic Gaussian based feedback control of interior noise in a rectangular box cavity with a flexible plate with single and multiple pairs of piezoelectric sensor-actuator patches when broadband disturbances act on the plate. The performance is compared with an "acoustic filter" that models the complete transfer function from the structure to the acoustic domain. The sensing performance is also compared with a direct estimation strategy.

  4. Acoustic sensing of renal stone fragmentation in extracorporeal shockwave lithotripsy

    OpenAIRE

    Fedele, Fiammetta

    2008-01-01

    This thesis describes the research carried out by the author on the exploitation of acoustic emissions detected during extracorporeal shockwave lithotripsy (a non-invasive procedure for the treatment of urinary stones) to develop a new diagnostic system. The work formed part of a research project on lithotripsy undertaken by the University of Southampton in collaboration with Guy's and St Thomas' NHS Foundation Trust (London) and a UK based company, Precision Acoustics Ltd (Dorche...

  5. Acoustic Emission Sensing for Maritime Diesel Engine Performance and Health

    Science.gov (United States)

    2016-05-01

    system does not provide direct current power to the preamplifier, equivalent pre-amplifiers with external power inputs were purchased , but the... behaviour of piston ring/cylinder liner interaction in diesel engines using acoustic emission. Tribology International 39 (12) 12 / 01 / 1634-1642...diesel engine using in-cylinder pressure and acoustic emission techniques. Dyanmics for Sustainable Engineering 1 454-463 26. Lowe, D. P., et al

  6. Ion-acoustic waves in ultracold neutral plasmas: Modulational instability and dissipative rogue waves

    Energy Technology Data Exchange (ETDEWEB)

    El-Tantawy, S.A., E-mail: samireltantawy@yahoo.com

    2017-02-26

    Progress is reported on the modulational instability (MI) of ion-acoustic waves (IAWs) and dissipative rogue waves (RWs) in ultracold neutral plasmas (UNPs). The UNPs consist of inertial ions fluid and Maxwellian inertialess hot electrons, and the presence of an ion kinematic viscosity is allowed. For this purpose, a modified nonlinear Schrödinger equation (NLSE) is derived and then solved analytically to show the occurrence of MI. It is found that the (in)stability regions of the wavepacks are dependent on time due to of the existence of the dissipative term. The existing regions of the MI of the IAWs are inventoried precisely. After that, we use a suitable transformation to convert the modified NLSE into the normal NLSE whose analytical solutions for rogue waves are known. The rogue wave propagation condition and its behavior are discussed. The impact of the relevant physical parameters on the profile of the RWs is examined. - Highlights: • UNPs are modeled by the phenomenological generalized hydrodynamic equations. • The derivative expansion method has been employed in order to derive a modified-NLSE. • A suitable transformation is used to transform the modified-NLSE into the standard NLSE. • The effect of the ion viscosity on the modulational instability and rogue waves is investigated.

  7. Large amplitude ion-acoustic solitary waves and double layers in multicomponent plasma with positrons

    International Nuclear Information System (INIS)

    Sabry, R.

    2009-01-01

    A finite amplitude theory for ion-acoustic solitary waves and double layers in multicomponent plasma consisting of hot positrons, cold ions, and electrons with two-electron temperature distributions is presented. Conditions are obtained under which large amplitude stationary ion-acoustic solitary waves and double layers can exist. For the physical parameters of interest, the ion-acoustic solitary wave (double layers) profiles and the relationship between the maximum soliton (double layers) amplitude and the Mach number are found. Also, we have presented the region of existence of the large amplitude ion-acoustic waves by analyzing the structure of the pseudopotential. For the selected range of parameters, it is found that only positive solitary waves and double layers can exist. An analysis for the small amplitude limit through the Sagdeev pseudopotential analysis and the reductive perturbation theory shows the existence of positive and negative ion-acoustic solitary waves and double layers. The effects of positron concentration and temperature ratio on the characteristics of the solitary ion-acoustic waves and double layers (namely, the amplitude and width) are discussed in detail. The relevance of this investigation to space and laboratory plasmas is pointed out.

  8. Topology optimization of bounded acoustic problems using the hybrid finite element-wave based method

    DEFF Research Database (Denmark)

    Goo, Seongyeol; Wang, Semyung; Kook, Junghwan

    2017-01-01

    This paper presents an alternative topology optimization method for bounded acoustic problems that uses the hybrid finite element-wave based method (FE-WBM). The conventional method for the topology optimization of bounded acoustic problems is based on the finite element method (FEM), which...

  9. 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.

  10. 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

  11. Detection of Metallic and Electronic Radar Targets by Acoustic Modulation of Electromagnetic Waves

    Science.gov (United States)

    2017-07-01

    by Acoustic Modulation of Electromagnetic Waves 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Gregory J... Program 13 List of Symbols, Abbreviations, and Acronyms 18 Distribution List 19 Approved for public release; distribution is...4 Fig. 4 Flowchart of wireless experiment to receive acoustically modulated radar waveforms

  12. Attenuation compensation in least-squares reverse time migration using the visco-acoustic wave equation

    KAUST Repository

    Dutta, Gaurav; Lu, Kai; Wang, Xin; Schuster, Gerard T.

    2013-01-01

    Attenuation leads to distortion of amplitude and phase of seismic waves propagating inside the earth. Conventional acoustic and least-squares reverse time migration do not account for this distortion which leads to defocusing of migration images

  13. Spatial Processing of Urban Acoustic Wave Fields from High-Performance Computations

    National Research Council Canada - National Science Library

    Ketcham, Stephen A; Wilson, D. K; Cudney, Harley H; Parker, Michael W

    2007-01-01

    .... The objective of this work is to develop spatial processing techniques for acoustic wave propagation data from three-dimensional high-performance computations to quantify scattering due to urban...

  14. Artificial Boundary Conditions for the Numerical Simulation of Unsteady Acoustic Waves

    National Research Council Canada - National Science Library

    Tsynkov, S. V

    2003-01-01

    We construct non-local artificial boundary conditions (ABCs) for the numerical simulation of genuinely time-dependent acoustic waves that propagate from a compact source in an unbounded unobstructed space...

  15. Excitation of an ion-acoustic wave by two whistlers in a collisionless magnetoplasma

    International Nuclear Information System (INIS)

    Sodha, M.S.; Singh, T.; Singh, D.P.; Sharma, R.P.

    1981-01-01

    An investigation is made into the excitation of an ion-acoustic wave in a collisionless hot magnetoplasma by two whistlers. On account of the interaction of the two whistlers, of frequencies ω 1 and ω 2 , ponderomotive force at frequency Δω(=ω 1 -ω 2 ) leads to the generation of an ion-acoustic wave. When the two whistlers have initially Gaussian intensity distributions, a d.c. component of the ponderomotive force leads to the redistribution of the background electron/ion density, and cross-focusing of the whistlers occurs. The power of the generated ion-acoustic wave, being dependent on the background ion density and powers of the whistlers, is further modified. The ion-acoustic wave power also changes drastically with the strength of the static magnetic field. (author)

  16. 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.

  17. Emergence of acoustic waves from vorticity fluctuations: impact of non-normality.

    Science.gov (United States)

    George, Joseph; Sujith, R I

    2009-10-01

    Chagelishvili et al. [Phys. Rev. Lett. 79, 3178 (1997)] discovered a linear mechanism of acoustic wave emergence from vorticity fluctuations in shear flows. This paper illustrates how this "nonresonant" phenomenon is related to the non-normality of the operator governing the linear dynamics of disturbances in shear flows. The non-self-adjoint nature of the governing operator causes the emergent acoustic wave to interact strongly with the vorticity disturbance. Analytical expressions are obtained for the nondivergent vorticity perturbation. A discontinuity in the x component of the velocity field corresponding to the vorticity disturbance was originally identified to be the cause of acoustic wave emergence. However, a different mechanism is proposed in this paper. The correct "acoustic source" is identified and the reason for the abrupt nature of wave emergence is explained. The impact of viscous damping is also discussed.

  18. Interaction of Acoustic Waves with a Cryogenic Nitrogen Jet at Sub- and Supercritical Pressures

    National Research Council Canada - National Science Library

    Chehroudi, B

    2001-01-01

    To better understand the nature of the interaction between acoustic waves and liquid fuel jets in rocket engines, cryogenic liquid nitrogen is injected into a room temperature high-pressure chamber...

  19. The Characterization of Surface Acoustic Wave Devices Based on AlN-Metal Structures

    Directory of Open Access Journals (Sweden)

    Lin Shu

    2016-04-01

    Full Text Available We report in this paper on the study of surface acoustic wave (SAW resonators based on an AlN/titanium alloy (TC4 structure. The AlN/TC4 structure with different thicknesses of AlN films was simulated, and the acoustic propagating modes were discussed. Based on the simulation results, interdigital transducers with a periodic length of 24 μm were patterned by lift-off photolithography techniques on the AlN films/TC4 structure, while the AlN film thickness was in the range 1.5–3.5 μm. The device performances in terms of quality factor (Q-factor and electromechanical coupling coefficient (k2 were determined from the measure S11 parameters. The Q-factor and k2 were strongly dependent not only on the normalized AlN film thickness but also on the full-width at half-maximum (FWHM of AlN (002 peak. The dispersion curve of the SAW phase velocity was analyzed, and the experimental results showed a good agreement with simulations. The temperature behaviors of the devices were also presented and discussed. The prepared SAW resonators based on AlN/TC4 structure have potential applications in integrated micromechanical sensing systems.

  20. Microwave and millimeter-wave remote sensing for security applications

    CERN Document Server

    Nanzer, Jeffrey

    2012-01-01

    Microwave and millimeter-wave remote sensing techniques are fast becoming a necessity in many aspects of security as detection and classification of objects or intruders becomes more difficult. This groundbreaking resource offers you expert guidance in this burgeoning area. It provides you with a thorough treatment of the principles of microwave and millimeter-wave remote sensing for security applications, as well as practical coverage of the design of radiometer, radar, and imaging systems. You learn how to design active and passive sensors for intruder detection, concealed object detection,

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

    International Nuclear Information System (INIS)

    Kozin, I.D.; Marchenko, M.V.

    1998-01-01

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

  2. Computation of Acoustic Waves Through Sliding-Zone Interfaces Using an Euler/Navier-Stokes Code

    Science.gov (United States)

    Rumsey, Christopher L.

    1996-01-01

    The effect of a patched sliding-zone interface on the transmission of acoustic waves is examined for two- and three-dimensional model problems. A simple but general interpolation scheme at the patched boundary passes acoustic waves without distortion, provided that a sufficiently small time step is taken. A guideline is provided for the maximum permissible time step or zone speed that gives an acceptable error introduced by the sliding-zone interface.

  3. Ion temperature effect on the propagation of ion acoustic solitary waves in a relativistic magnetoplasma

    International Nuclear Information System (INIS)

    Salahuddin, M.

    1990-01-01

    Using the reductive perturbation technique the Korteweg-de Vries (KdV) equation is derived for ion acoustic waves, in the presence of weak relativistic effects and warm ions, in a magnetized plasma. The influence of non ideal effects on the amplitude and width of the ion acoustic solitary waves is also discussed. The results are depicted in the figures. It is shown that the simultaneous presence of ion streaming and magnetic field stops the tendency of soliton breaking. (author)

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

    KAUST Repository

    Graber, Philip Jameson; Said-Houari, Belkacem

    2012-01-01

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

  5. Acoustic wave propagation in fluids with coupled chemical reactions

    International Nuclear Information System (INIS)

    Margulies, T.S.; Schwarz, W.H.

    1984-08-01

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

  6. Reflection of ion acoustic waves by the plasma sheath

    International Nuclear Information System (INIS)

    Ibrahim, I.; Kuehl, H.H.

    1984-01-01

    The reflection coefficient R for linear monochromatic ion acoustic waves incident on the transonic layer and sheath from the plasma interior is calculated. The treatment differs from previous analyses in that (1) the exact zero-order ion density and velocity profiles for a planar, bounded plasma are used, and the zero-order charge separation is not neglected, and (2) the first-order quantities near the transonic layer are considered in detail, including first-order charge separation, whereby it is found that no coupling to the beam modes exists, and that the functional form of the first-order solution is completely determined. It is shown that the upper bound for Vertical BarRVertical Bar is (1)/(3) . The largest reflection occurs for frequencies which are small compared with the ionization frequency, and generally decreases with increasing frequency. By Fourier superposition, the reflection of a pulse is computed. For a narrow incident pulse, the reflected pulse is greatly distorted and is small compared with the incident pulse. For a broad pulse, the reflected pulse is similar in shape to the incident pulse, and has a magnitude which is approximately (1)/(3) of the incident pulse

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

    KAUST Repository

    Graber, Philip Jameson

    2012-05-01

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

  8. Acoustic wave therapy for cellulite, body shaping and fat reduction.

    Science.gov (United States)

    Hexsel, Doris; Camozzato, Fernanda Oliveira; Silva, Aline Flor; Siega, Carolina

    2017-06-01

    Cellulite is a common aesthetic condition that affects almost every woman. To evaluate the efficacy of acoustic wave therapy (AWT) for cellulite and body shaping. In this open-label, single-centre trial, 30 women presenting moderate or severe cellulite underwent 12 sessions of AWT on the gluteus and back of the thighs, over six weeks. The following assessments were performed at baseline, and up to 12 weeks after treatment: Cellulite Severity Scale (CSS), body circumference measurements, subcutaneous fat thickness by magnetic resonance imaging (MRI), quality of life related by Celluqol ® and a satisfaction questionnaire. The treatment reduced cellulite severity from baseline up to 12 weeks after the last treatment session (subjects presenting severe cellulite: 60% to 38%). The mean CSS shifted from 11.1 to 9.5 (p treatment also improved quality of life. More than 90% of the subjects would undergo the treatment again and 89% were satisfied with the results. No serious adverse events were reported. AWT is a safe treatment to improve cellulite appearance and reduce body circumferences.

  9. 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.

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

    Science.gov (United States)

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

    2012-08-07

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

  11. Phonon-impurity relaxation and acoustic wave absorption in yttrium-aluminium garnet crystals with impurities

    International Nuclear Information System (INIS)

    Ivanov, S.N.; Kotelyanskij, I.M.; Medved', V.V.

    1983-01-01

    The experimental results of investigations of the influence of substitution impurities in the yttrium-aluminium garnet lattice on absorption of high-frequency acoustic waves are presented. It is shown that the phonon-impurity relaxation processses affect at most the wave absorption and have resonance character when the acoustic wave interacts with the thermal phonon group in the vicinity of the perturbed part of the phonon spectrum caused by the impurity. The differences of time values between inelastic and elastic thermal phonons relaxations determined from the data on longitudinal and shear waves in pure and impurity garnet crystals are discussed

  12. Measurements of the power spectrum and dispersion relation of self-excited dust acoustic waves

    Science.gov (United States)

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

    2009-12-01

    The spectrum of spontaneously excited dust acoustic waves was measured. The waves were observed with high temporal resolution using a fast video camera operating at 1000 frames per second. The experimental system was a suspension of micron-size kaolin particles in the anode region of a dc discharge in argon. Wave activity was found at frequencies as high as 450 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 instead. The cutoff value declined with distance from the anode. We ascribe the observed cutoff to the particle confinement in this region.

  13. Interaction between counter-streaming ion-acoustic solitons and the Langmuir waves

    International Nuclear Information System (INIS)

    Basovich, A.Ya.; Gromov, E.M.; Talanov, V.I.

    1984-01-01

    The interaction between strong counter-streaming ion-acoustic solitons and the Langmuir waves is considered. At first the Langmuir waves spectrum transformation by counter-streaming ion-acoustic solutions of a preset amplitude e has been found. An increase in the frequency and number of the Langmuir waves due to the Doppler effect in the course of multiple reflection from the f front soliton slope has been determined and the wave number range in which the confinement of the Langmuir waves by counter-streaning solitons is possible has s been found. It is shown that the time of the Langmuir wave transformation into the short-wave region under the effect of the counter-streaming soliton may y be short as compared with the time of the Langmuir wave diffusion into the Landau damping region under the effect of random fields of ion-acoustic waves. In the adiabatic fpproximation changes in the counter-streaming ion acoustic parameters of solitons owing to the Langmuir waves have been

  14. THz wave sensing for petroleum industrial applications

    Science.gov (United States)

    Al-Douseri, Fatemah M.; Chen, Yunqing; Zhang, X.-C.

    2006-04-01

    We present the results of terahertz (THz) sensing of gasoline products. The frequency-dependent absorption coefficients, refractive indices, and complex dielectric constants of gasoline and xylene isomers were extracted in the spectral range from 0.5 3.0 THz. The THz spectra of gasoline (#87, #89, #93) and related BTEX (benzene, toluene, ethylbenzene, and xylene) compounds were studied by using Fourier transform infrared spectroscopy (FTIR) in the 1.5 20 THz (50 660 cm-1). The xylene isomers, which are used as antiknock agent in gasoline were determined quantitatively in gasoline in the THz range. Our investigations show the potential of THz technology for the petroleum industrial applications.

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

    Directory of Open Access Journals (Sweden)

    Marina V. Voinova

    2009-01-01

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

  16. 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.

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

    Science.gov (United States)

    Hasan, Nusair; Farouk, Bakhtier

    2015-10-01

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

  18. Nonlinear ion-acoustic cnoidal waves in a dense relativistic degenerate magnetoplasma.

    Science.gov (United States)

    El-Shamy, E F

    2015-03-01

    The complex pattern and propagation characteristics of nonlinear periodic ion-acoustic waves, namely, ion-acoustic cnoidal waves, in a dense relativistic degenerate magnetoplasma consisting of relativistic degenerate electrons and nondegenerate cold ions are investigated. By means of the reductive perturbation method and appropriate boundary conditions for nonlinear periodic waves, a nonlinear modified Korteweg-de Vries (KdV) equation is derived and its cnoidal wave is analyzed. The various solutions of nonlinear ion-acoustic cnoidal and solitary waves are presented numerically with the Sagdeev potential approach. The analytical solution and numerical simulation of nonlinear ion-acoustic cnoidal waves of the nonlinear modified KdV equation are studied. Clearly, it is found that the features (amplitude and width) of nonlinear ion-acoustic cnoidal waves are proportional to plasma number density, ion cyclotron frequency, and direction cosines. The numerical results are applied to high density astrophysical situations, such as in superdense white dwarfs. This research will be helpful in understanding the properties of compact astrophysical objects containing cold ions with relativistic degenerate electrons.

  19. Generation of ion-acoustic and magnetoacoustic waves in an RF helicon discharge

    International Nuclear Information System (INIS)

    Belov, A. S.; Markov, G. A.

    2006-01-01

    A study is made of the generation of ion-acoustic and magnetoacoustic waves in a discharge excited in an external magnetic field by an electromagnetic wave in the whistler frequency range (ω LH He , where ω LH = √(ω He ω Hi ) and ω He and ω Hi are the electron and ion gyrofrequencies, respectively). The excitation of acoustic waves is attributed to the decay of a high-frequency hybrid mode forming a plasma waveguide into low-frequency acoustic waves and new high-frequency waves that satisfy both the decay conditions and the waveguide dispersion relations. The excitation of acoustic waves is resonant in character because the conditions for the generation of waveguide modes and for the occurrence of the corresponding nonlinear wave processes should be satisfied simultaneously. An unexpected effect is the generation of magnetoacoustic waves by whistlers. A diagnostic technique is proposed that allows one to determine the thermal electron velocity by analyzing decay conditions and dispersion relations for waves in the discharge channel

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

    Science.gov (United States)

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

    2016-05-01

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

  1. Multi-functional surface acoustic wave sensor for monitoring enviromental and structural condition

    Science.gov (United States)

    Furuya, Y.; Kon, T.; Okazaki, T.; Saigusa, Y.; Nomura, T.

    2006-03-01

    As a first step to develop a health monitoring system with active and embedded nondestructive evaluation devices for the machineries and structures, multi-functional SAW (surface acoustic wave) device was developed. A piezoelectric LiNbO3(x-y cut) materials were used as a SAW substrate on which IDT(20μm pitch) was produced by lithography. On the surface of a path of SAW between IDTs, environmentally active material films of shape memory Ti50Ni41Cu(at%) with non-linear hysteresis and superelastic Ti48Ni43Cu(at%) with linear deformation behavior were formed by magnetron-sputtering technique. In this study, these two kinds of shape memory alloys SMA) system were used to measure 1) loading level, 2) phase transformation and 3)stress-strain hysteresis under cyclic loading by utilizing their linearity and non-linearity deformation behaviors. Temperature and stress dependencies of SAW signal were also investigated in the non-sputtered film state. Signal amplitude and phase change of SAW were chosen to measure as the sensing parameters. As a result, temperature, stress level, phase transformation in SMA depending on temperature and mechanical damage accumulation could be measured by the proposed multi-functional SAW sensor. Moreover, the wireless SAW sensing system which has a unique feature of no supplying electric battery was constructed, and the same characteristic evaluation is confirmed in comparison with wired case.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  3. Ion acoustic waves in one- and two-negative ion species plasmas

    International Nuclear Information System (INIS)

    Ichiki, Ryuta; Shindo, Masako; Yoshimura, Shinji; Watanabe, Tsuguhiro; Kawai, Yoshinobu

    2001-01-01

    Ion acoustic waves in multi-ion plasmas including two negative ion species are investigated both numerically and experimentally. Numerically, the kinetic dispersion relation in two-negative ion plasmas is investigated. There are three modes of the ion acoustic waves in two-negative ion plasmas. In an Ar + -F - -SF 6 - plasma, only one of the three modes is dominant, regardless of the values of the electron and the ion temperatures. In a Xe + -F - -SF 6 - plasma, on the other hand, two modes can be important for a certain range of the electron-ion temperature ratio. The results also imply the possibility of the coexistence of the fast mode and the slow mode in one-negative ion plasmas. Experimentally, ion acoustic waves are observed in an Ar + -F - -SF 6 - plasma and are found to show a mode transition that agrees with the theoretical prediction for one of the three ion acoustic modes

  4. 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.

  5. On the Detectability of Acoustic Waves Induced Following Irradiation by a Radiotherapy Linear Accelerator.

    Science.gov (United States)

    Hickling, Susannah; Leger, Pierre; El Naqa, Issam

    2016-02-11

    Irradiating an object with a megavoltage photon beam generated by a clinical radiotherapy linear accelerator (linac) induces acoustic waves through the photoacoustic effect. The detection and characterization of such acoustic waves has potential applications in radiation therapy dosimetry. The purpose of this work was to gain insight into the properties of such acoustic waves by simulating and experimentally detecting them in a well-defined system consisting of a metal block suspended in a water tank. A novel simulation workflow was developed by combining radiotherapy Monte Carlo and acoustic wave transport simulation techniques. Different set-up parameters such as photon beam energy, metal block depth, metal block width, and metal block material were varied, and the simulated and experimental acoustic waveforms showed the same relative amplitude trends and frequency variations for such setup changes. The simulation platform developed in this work can easily be extended to other irradiation situations, and will be an invaluable tool for developing a radiotherapy dosimetry system based on the detection of the acoustic waves induced following linear accelerator irradiation.

  6. 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.

  7. The grain charging and the dust acoustic wave instability

    International Nuclear Information System (INIS)

    Varma, Ram K.

    2001-01-01

    The stability of the steady charging state of the assembly of dust grains in a plasma is analyzed using, besides the equations of continuity and momentum balance, also the equations of thermal energy balance with the grain charging terms for both the electron and ion species. The grain charging terms account for the energy exchange between the dust grains and the electron and ion fluids. The grains are taken to be immobile for the purpose of this analysis. Two limiting cases are analyzed: (i) f(≡4πn d λ D 2 a) >1 (n d is the dust number density, λ D plasma Debye length, and a, the grain radius). The steady grain charge state is found to be stable in the case f o is unaffected. On the other hand, in the limit f>>1, the state is found to be unstable provided γ q (≡q o e/aT e ) e -T i )/T e (T e , T i are electron and ion temperatures). A coherent charging of the dust grains results as a consequence of this instability until γ q ≅(1/2) (T e -T i )/T i . Next, by letting the grain charges be mobile, so that the perturbation of dust number density is nonzero, we examine the stability of the dust-acoustic wave (DAW). The DAW is found to be unstable, also in the f>>1 case, while stable in the f<<1. The instability of the DAW also implies a concomitant grain charge growth, which would again be of a coherent nature

  8. 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...

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

    Science.gov (United States)

    Chitta, Subhashini; Steinhoff, John

    2015-11-01

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

  10. On an Acoustic Wave Equation Arising in Non-Equilibrium Gasdynamics. Classroom Notes

    Science.gov (United States)

    Chandran, Pallath

    2004-01-01

    The sixth-order wave equation governing the propagation of one-dimensional acoustic waves in a viscous, heat conducting gaseous medium subject to relaxation effects has been considered. It has been reduced to a system of lower order equations corresponding to the finite speeds occurring in the equation, following a method due to Whitham. The lower…

  11. 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

  12. 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).

  13. Propagation of ion-acoustic waves in a dusty plasma with non ...

    Indian Academy of Sciences (India)

    [1] to investigate the various salient features of solitary waves in a cold, collisionless ... Moreover, the K-dV theory was applied to ion-acoustic waves by Zakharov ..... to an equation involving term like φ5/2 where the ordinary integration method fails .... Moreover, in this case our attention is drawn to the fact that the rate of.

  14. 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...

  15. Reflection and Transmission of Acoustic Waves through the Layer of Multifractional Bubbly Liquid

    Directory of Open Access Journals (Sweden)

    Gubaidullin Damir Anvarovich

    2018-01-01

    Full Text Available The mathematical model that determines reflection and transmission of acoustic wave through a medium containing multifractioanl bubbly liquid is presented. For the water-water with bubbles-water model the wave reflection and transmission coefficients are calculated. The influence of the bubble layer thickness on the investigated coefficients is shown. The theory compared with the experiment. It is shown that the theoretical results describe and explain well the available experimental data. It is revealed that the special dispersion and dissipative properties of the layer of bubbly liquid can significantly influence on the reflection and transmission of acoustic waves in multilayer medium

  16. Energy Properties of Ion Acoustic Waves in Stable and Unstable Plasmas

    DEFF Research Database (Denmark)

    Jensen, Vagn Orla; Lynov, Jens-Peter

    1979-01-01

    Energy exchange between potential energy and ion kinetic energy in an ion acoustic wave is considered. In order to investigate the linear Landau damping or growth, the energy is calculated by use of first‐order quantities only so that nonlinear effects are not involved. It is found that for ion...... acoustic waves that are growing or damped in space the time average of the sum of the potential and the kinetic energy density is independent of position. Energy absorption spectra in particle velocity space are calculated; they are relatively broad and complicated functions. This shows that plasma ions...... of all velocities exchange energy with the wave....

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  18. Electron acoustic solitary waves in unmagnetized two electron population dense plasmas

    International Nuclear Information System (INIS)

    Mahmood, S.; Masood, W.

    2008-01-01

    The electron acoustic solitary waves are studied in unmagnetized two population electron quantum plasmas. The quantum hydrodynamic model is employed with the Sagdeev potential approach to describe the arbitrary amplitude electron acoustic waves in a two electron population dense Fermi plasma. It is found that hot electron density hump structures are formed in the subsonic region in such type of quantum plasmas. The wave amplitude as well as the width of the soliton are increased with the increase of percentage presence of cold (thinly populated) electrons in a multicomponent quantum plasma. It is found that an increase in quantum diffraction parameter broadens the nonlinear structure. Furthermore, the amplitude of the nonlinear electron acoustic wave is found to increase with the decrease in Mach number. The numerical results are also presented to understand the formation of solitons in two electron population Fermi plasmas.

  19. 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.

  20. Ion acoustic solitary waves in a dusty plasma obliquely propagating to an external magnetic field

    International Nuclear Information System (INIS)

    Choi, Cheong Rim; Ryu, Chang-Mo; Lee, Nam C.; Lee, D.-Y.

    2005-01-01

    The nonlinear ion acoustic solitary wave in a magnetized dusty plasma, obliquely propagating to the embedding external magnetic field, is revisited. It is found that when the charge density of dust particles is high, the Sagdeev potential needs to be expanded up to δn 4 near n=1. In this case, it is shown that there could exist rarefactive ion acoustic solitary waves as well as the kink-type double layer solutions, in addition to the conventional hump-type ones found in the δn 3 expansion. The amplitude variations of ion acoustic solitary waves in a magnetized dusty plasma are also examined with respect to the change of the dust charge density and the wave directional angle

  1. Large amplitude ion-acoustic waves in a plasma with an electron beam

    International Nuclear Information System (INIS)

    Nejoh, Y.; Sanuki, H.

    1995-01-01

    The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with an electron beam, by the pseudopotential method. The region of the existence of large amplitude ion-acoustic waves is examined, showing that the condition of the existence sensitively depends on the parameters such as the electron beam temperature, the ion temperature, the electrostatic potential, and the concentration of the electron beam density. It turns out that the region of the existence spreads as the beam temperature increases but the effect of the electron beam velocity is relatively small. New findings of large amplitude ion-acoustic waves in a plasma with an electron beam are predicted. copyright 1995 American Institute of Physics

  2. Effect of drift-acoustic waves on magnetic island stability in slab geometry

    International Nuclear Information System (INIS)

    Fitzpatrick, R.; Waelbroeck, F.L.

    2005-01-01

    A mathematical formalism is developed for calculating the ion polarization term in the Rutherford island width evolution equation in the presence of drift-acoustic waves. The calculation is fully nonlinear, includes both ion and electron diamagnetic effects, as well as ion compressibility, but is performed in slab geometry. Magnetic islands propagating in a certain range of phase velocities are found to emit drift-acoustic waves. Wave emission gives rise to rapid oscillations in the ion polarization term as the island phase velocity varies, and also generates a net electromagnetic force acting on the island region. Increasing ion compressibility is found to extend the range of phase velocities over which drift-acoustic wave emission occurs in the electron diamagnetic direction

  3. Nonlinear theory of ion-acoustic waves in an ideal plasma with degenerate electrons

    International Nuclear Information System (INIS)

    Dubinov, A. E.; Dubinova, A. A.

    2007-01-01

    A nonlinear theory is constructed that describes steady-state ion-acoustic waves in an ideal plasma in which the electron component is a degenerate Fermi gas and the ion component is a classical gas. The parameter ranges in which such a plasma can exist are determined, and dispersion relations for ion-acoustic waves are obtained that make it possible to find the linear ion-acoustic velocity. Analytic gas-dynamic models of ion sound are developed for a plasma with the ion component as a cold, an isothermal, or an adiabatic gas, and moreover, the solutions to the equations of all the models are brought to a quadrature form. Profiles of a subsonic periodic and a supersonic solitary wave are calculated, and the upper critical Mach numbers of a solitary wave are determined. For a plasma with cold ions, the critical Mach number is expressed by an explicit exact formula

  4. 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.

  5. 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.

  6. Nonlinear ion acoustic waves in a quantum degenerate warm plasma with dust grains

    International Nuclear Information System (INIS)

    Dubinov, A. E.; Kolotkov, D. Yu.; Sazonkin, M. A.

    2011-01-01

    A study is made of the propagation of ion acoustic waves in a collisionless unmagnetized dusty plasma containing degenerate ion and electron gases at nonzero temperatures. In linear theory, a dispersion relation for isothermal ion acoustic waves is derived and an exact expression for the linear ion acoustic velocity is obtained. The dependence of the linear ion acoustic velocity on the dust density in a plasma is calculated. An analysis of the dispersion relation reveals parameter ranges in which the problem has soliton solutions. In nonlinear theory, an exact solution to the basic equations is found and examined. The analysis is carried out by Bernoulli’s pseudopotential method. The ranges of the phase velocities of periodic ion acoustic waves and the velocities of solitons are determined. It is shown that these ranges do not overlap and that the soliton velocity cannot be lower than the linear ion acoustic velocity. The profiles of the physical quantities in a periodic wave and in a soliton are evaluated, as well as the dependence of the critical velocity of solitons on the dust density in a plasma.

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

    International Nuclear Information System (INIS)

    Tournat, V.; Gusev, V.E.; Castagnede, B.

    2004-01-01

    First laboratory-scale experimental observation of both subharmonics excitation and significant increase in noise level caused by propagation of the acoustic wave in unconsolidated granular material is reported. The bifurcation phenomenon, taking place above a critical level of acoustic excitation (and opening the subharmonics route to chaos) is attributed to the interaction of acoustic wave with distributed system of highly nonlinear inter-grain contacts. The estimates demonstrated that these are weak contacts (loaded at least two orders of magnitude weaker than in average) that might be responsible for the observed nonlinear effects. The additional intermittent contacts created by the acoustic wave (which are open in the absence of acoustic loading) can also contribute. In the clapping (tapping) regime, each of these contacts individually is similar to an impact oscillator, for which the scenario of period doubling cascade and the transition to chaotic behavior has been predicted theoretically and observed experimentally earlier. The experiments confirm that the nonlinear interactions of acoustic waves in granular assemblages are highly sensitive to the fraction of weakly loaded (and unloaded) contacts, information on which is difficult to access by any other experimental methods

  8. 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)

  9. Guided Wave Sensing In a Carbon Steel Pipe Using a Laser Vibrometer System

    Science.gov (United States)

    Ruíz Toledo, Abelardo; Salazar Soler, Jordi; Chávez Domínguez, Juan Antonio; García Hernández, Miguel Jesús; Turó Peroy, Antoni

    2010-05-01

    Non-Destructive Evaluation (NDE) techniques have achieved a great development during the last decades as a valuable tool for material characterization, manufacturing control and structural integrity tests. Among these tools, the guided wave technology has been rapidly extended because it reduces inspection time and costs compared to the ordinary point by point testing in large structures, as well as because of the possibility of inspecting under insulation and coating conditions. This fast development has motivated the creation of several inspection and material characterization systems including different technologies which can be combined with this technique. Different measurements systems based on laser techniques have been presented in order to inspect pipes, plates and diverse structures. Many of them are experimental systems of high cost and complexity which combine the employment of a laser for generation of waves in the structure and an interferometer for detection. Some of them employ air-coupled ultrasound generation transducers, with high losses in air and which demand high energy for exciting waves in materials of high stiffness. The combined employment of a commercial vibrometer system for Lamb wave sensing in plates has been successfully shown in the literature. In this paper we present a measurement system based on the combined employment of a piezoelectric wedge transducer and a laser vibrometer to sense guided acoustic waves in carbon steel pipes. The measurement system here presented is mainly compounded of an angular wedge transducer, employed to generate the guided wave and a commercial laser vibrometer used in the detection process. The wedge transducer is excited by means of a signal function generator whose output signal has been amplified with a power signal amplifier. A high precision positioning system is employed to place the laser beam at different points through the pipe surface. The signal detected by the laser vibrometer system is

  10. Electronic transport through single-molecule magnets in the presence of an acoustic wave

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gwang-Hee [Sejong University, Seoul (Korea, Republic of)

    2010-12-15

    Employing the Fermi golden rule and the rotating wave approximation, we calculate the electrical conductivity through a single-molecule magnet (SMM) coupled to the electrodes in the presence of the acoustic wave. We show that the sound wave can generate quantum beats of the conductance around the resonant field. The oscillatory behavior of the conductance depends on different resonances and the sweeping field's speed.

  11. Acoustic Wave Propagation in Snow Based on a Biot-Type Porous Model

    Science.gov (United States)

    Sidler, R.

    2014-12-01

    Despite the fact that acoustic methods are inexpensive, robust and simple, the application of seismic waves to snow has been sparse. This might be due to the strong attenuation inherent to snow that prevents large scale seismic applications or due to the somewhat counterintuitive acoustic behavior of snow as a porous material. Such materials support a second kind of compressional wave that can be measured in fresh snow and which has a decreasing wave velocity with increasing density of snow. To investigate wave propagation in snow we construct a Biot-type porous model of snow as a function of porosity based on the assumptions that the solid frame is build of ice, the pore space is filled with a mix of air, or air and water, and empirical relationships for the tortuosity, the permeability, the bulk, and the shear modulus.We use this reduced model to investigate compressional and shear wave velocities of snow as a function of porosity and to asses the consequences of liquid water in the snowpack on acoustic wave propagation by solving Biot's differential equations with plain wave solutions. We find that the fast compressional wave velocity increases significantly with increasing density, but also that the fast compressional wave velocity might be even lower than the slow compressional wave velocity for very light snow. By using compressional and shear strength criteria and solving Biot's differential equations with a pseudo-spectral approach we evaluate snow failure due to acoustic waves in a heterogeneous snowpack, which we think is an important mechanism in triggering avalanches by explosives as well as by skiers. Finally, we developed a low cost seismic acquisition device to assess the theoretically obtained wave velocities in the field and to explore the possibility of an inexpensive tool to remotely gather snow water equivalent.

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

    DEFF Research Database (Denmark)

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

    1968-01-01

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

  13. Phase Aberration and Attenuation Effects on Acoustic Radiation Force-Based Shear Wave Generation.

    Science.gov (United States)

    Carrascal, Carolina Amador; Aristizabal, Sara; Greenleaf, James F; Urban, Matthew W

    2016-02-01

    Elasticity is measured by shear wave elasticity imaging (SWEI) methods using acoustic radiation force to create the shear waves. Phase aberration and tissue attenuation can hamper the generation of shear waves for in vivo applications. In this study, the effects of phase aberration and attenuation in ultrasound focusing for creating shear waves were explored. This includes the effects of phase shifts and amplitude attenuation on shear wave characteristics such as shear wave amplitude, shear wave speed, shear wave center frequency, and bandwidth. Two samples of swine belly tissue were used to create phase aberration and attenuation experimentally. To explore the phase aberration and attenuation effects individually, tissue experiments were complemented with ultrasound beam simulations using fast object-oriented C++ ultrasound simulator (FOCUS) and shear wave simulations using finite-element-model (FEM) analysis. The ultrasound frequency used to generate shear waves was varied from 3.0 to 4.5 MHz. Results: The measured acoustic pressure and resulting shear wave amplitude decreased approximately 40%-90% with the introduction of the tissue samples. Acoustic intensity and shear wave displacement were correlated for both tissue samples, and the resulting Pearson's correlation coefficients were 0.99 and 0.97. Analysis of shear wave generation with tissue samples (phase aberration and attenuation case), measured phase screen, (only phase aberration case), and FOCUS/FEM model (only attenuation case) showed that tissue attenuation affected the shear wave generation more than tissue aberration. Decreasing the ultrasound frequency helped maintain a focused beam for creation of shear waves in the presence of both phase aberration and attenuation.

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

    Science.gov (United States)

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

    2014-12-01

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

  15. Acoustic streaming induced by two orthogonal ultrasound standing waves in a microfluidic channel.

    Science.gov (United States)

    Doinikov, Alexander A; Thibault, Pierre; Marmottant, Philippe

    2018-07-01

    A mathematical model is derived for acoustic streaming in a microfluidic channel confined between a solid wall and a rigid reflector. Acoustic streaming is produced by two orthogonal ultrasound standing waves of the same frequency that are created by two pairs of counter-propagating leaky surface waves induced in the solid wall. The magnitudes and phases of the standing waves are assumed to be different. Full analytical solutions are found for the equations of acoustic streaming. The obtained solutions are used in numerical simulations to reveal the structure of the acoustic streaming. It is shown that the interaction of two standing waves leads to the appearance of a cross term in the equations of acoustic streaming. If the phase lag between the standing waves is nonzero, the cross term brings about circular vortices with rotation axes perpendicular to the solid wall of the channel. The vortices make fluid particles rotate and move alternately up and down between the solid wall and the reflector. The obtained results are of immediate interest for acoustomicrofluidic applications such as the ultrasonic micromixing of fluids and the manipulation of microparticles. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Speech coding, reconstruction and recognition using acoustics and electromagnetic waves

    International Nuclear Information System (INIS)

    Holzrichter, J.F.; Ng, L.C.

    1998-01-01

    The use of EM radiation in conjunction with simultaneously recorded acoustic speech information enables a complete mathematical coding of acoustic speech. The methods include the forming of a feature vector for each pitch period of voiced speech and the forming of feature vectors for each time frame of unvoiced, as well as for combined voiced and unvoiced speech. The methods include how to deconvolve the speech excitation function from the acoustic speech output to describe the transfer function each time frame. The formation of feature vectors defining all acoustic speech units over well defined time frames can be used for purposes of speech coding, speech compression, speaker identification, language-of-speech identification, speech recognition, speech synthesis, speech translation, speech telephony, and speech teaching. 35 figs

  17. Speech coding, reconstruction and recognition using acoustics and electromagnetic waves

    Science.gov (United States)

    Holzrichter, John F.; Ng, Lawrence C.

    1998-01-01

    The use of EM radiation in conjunction with simultaneously recorded acoustic speech information enables a complete mathematical coding of acoustic speech. The methods include the forming of a feature vector for each pitch period of voiced speech and the forming of feature vectors for each time frame of unvoiced, as well as for combined voiced and unvoiced speech. The methods include how to deconvolve the speech excitation function from the acoustic speech output to describe the transfer function each time frame. The formation of feature vectors defining all acoustic speech units over well defined time frames can be used for purposes of speech coding, speech compression, speaker identification, language-of-speech identification, speech recognition, speech synthesis, speech translation, speech telephony, and speech teaching.

  18. A Non-Intrusive GMA Welding Process Quality Monitoring System Using Acoustic Sensing.

    Science.gov (United States)

    Cayo, Eber Huanca; Alfaro, Sadek Crisostomo Absi

    2009-01-01

    Most of the inspection methods used for detection and localization of welding disturbances are based on the evaluation of some direct measurements of welding parameters. This direct measurement requires an insertion of sensors during the welding process which could somehow alter the behavior of the metallic transference. An inspection method that evaluates the GMA welding process evolution using a non-intrusive process sensing would allow not only the identification of disturbances during welding runs and thus reduce inspection time, but would also reduce the interference on the process caused by the direct sensing. In this paper a nonintrusive method for weld disturbance detection and localization for weld quality evaluation is demonstrated. The system is based on the acoustic sensing of the welding electrical arc. During repetitive tests in welds without disturbances, the stability acoustic parameters were calculated and used as comparison references for the detection and location of disturbances during the weld runs.

  19. Ion-acoustic shock waves with negative ions in presence of dust particulates

    International Nuclear Information System (INIS)

    Sarma, Arun; Nakamura, Y.

    2009-01-01

    Dust acoustics shock waves have been investigated experimentally in a homogeneous unmagnetized dusty plasma device containing negative ions. When the negative ion density larger than a critical concentration 'r c ' negative shock waves were observed instead of positive shock waves. Again when it is nearly equal to 'r c ' both positive and negative shock waves propagate. The experimental findings are compared with modified KdV-Burgers equation. The velocity of the shock waves are also measured and compared with the numerical integration of modified KdV-Burgers equation.

  20. 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

  1. Control of synchrotron x-ray diffraction by means of standing acoustic waves

    International Nuclear Information System (INIS)

    Zolotoyabko, E.; Quintana, J.P.

    2004-01-01

    Synchrotron x-ray diffraction measurements in quartz crystals of different thickness excited by standing acoustic waves were carried out at the Advanced Photon Source of Argonne National Laboratory. We demonstrated the ability to significantly modify the quartz rocking curves for 20-25 keV x rays by changing the shear wave parameters in the frequency range between 15 and 105 MHz. Dynamic deformation introduced into the crystal lattice by acoustic waves resulted in a remarkable broadening of the rocking curves. The broadening effect strongly depends on the strength of the ultrasound, which can be easily regulated by changing the acoustic amplitude or frequency near the resonance. The maximum rocking curve broadening reached 17 times, which corresponds to the wavelength band, Δλ/λ=4x10 -3 , when used as a monochromator or analyzer for 20-25 keV x rays. The initial rocking curve shape is restored by sweeping the acoustic frequency within a 50-100 kHz range near the resonance. The tunable broadening effect allows effective manipulation of x-ray intensities in time domain. Time-resolved x-ray diffraction measurements under a 19.6 MHz acoustic wave excitation were performed by synchronizing the acoustic wave and x-ray burst periodicity. We used the fact that twice per period the standing wave produces a zero net deformation across the crystal thickness. By introducing an oscillating delay to the acoustic excitation, we were able to effectively change the phase of the acoustic wave relative to the x-ray burst periodicity. The x-ray diffraction intensity was strongly affected by tuning the timing of the x-ray arrivals to the minimum or maximum acoustic deformation. A deep modulation of x rays was observed in a wide frequency range between 0.1 Hz and 1 MHz, which certifies that acoustically excited quartz crystals can potentially be used as slow and fast x-ray modulators with high duty cycle

  2. Particle filtering based structural assessment with acoustic emission sensing

    Science.gov (United States)

    Yan, Wuzhao; Abdelrahman, Marwa; Zhang, Bin; Ziehl, Paul

    2017-02-01

    Nuclear structures are designed to withstand severe loading events under various stresses. Over time, aging of structural systems constructed with concrete and steel will occur. This deterioration may reduce service life of nuclear facilities and/or lead to unnecessary or untimely repairs. Therefore, online monitoring of structures in nuclear power plants and waste storage has drawn significant attention in recent years. Of many existing non-destructive evaluation and structural monitoring approaches, acoustic emission is promising for assessment of structural damage because it is non-intrusive and is sensitive to corrosion and crack growth in reinforced concrete elements. To provide a rapid, actionable, and graphical means for interpretation Intensity Analysis plots have been developed. This approach provides a means for classification of damage. Since the acoustic emission measurement is only an indirect indicator of structural damage, potentially corrupted by non-genuine data, it is more suitable to estimate the states of corrosion and cracking in a Bayesian estimation framework. In this paper, we will utilize the accelerated corrosion data from a specimen at the University of South Carolina to develop a particle filtering-based diagnosis and prognosis algorithm. Promising features of the proposed algorithm are described in terms of corrosion state estimation and prediction of degradation over time to a predefined threshold.

  3. The nonlinear propagation of acoustic waves in a viscoelastic medium containing cylindrical micropores

    International Nuclear Information System (INIS)

    Yu-Lin, Feng; Xiao-Zhou, Liu; Jie-Hui, Liu; Li, Ma

    2009-01-01

    Based on an equivalent medium approach, this paper presents a model describing the nonlinear propagation of acoustic waves in a viscoelastic medium containing cylindrical micropores. The influences of pores' nonlinear oscillations on sound attenuation, sound dispersion and an equivalent acoustic nonlinearity parameter are discussed. The calculated results show that the attenuation increases with an increasing volume fraction of micropores. The peak of sound velocity and attenuation occurs at the resonant frequency of the micropores while the peak of the equivalent acoustic nonlinearity parameter occurs at the half of the resonant frequency of the micropores. Furthermore, multiple scattering has been taken into account, which leads to a modification to the effective wave number in the equivalent medium approach. We find that these linear and nonlinear acoustic parameters need to be corrected when the volume fraction of micropores is larger than 0.1%

  4. 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.

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

    CERN Document Server

    Sakamoto, Shinichi; Otsuru, Toru

    2014-01-01

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

  6. Acoustically mediated long-range interaction among multiple spherical particles exposed to a plane standing wave

    International Nuclear Information System (INIS)

    Zhang, Shenwei; Qiu, Chunyin; Wang, Mudi; Ke, Manzhu; Liu, Zhengyou

    2016-01-01

    In this work, we study the acoustically mediated interaction forces among multiple well-separated spherical particles trapped in the same node or antinode plane of a standing wave. An analytical expression of the acoustic interaction force is derived, which is accurate even for the particles beyond the Rayleigh limit. Interestingly, the multi-particle system can be decomposed into a series of independent two-particle systems described by pairwise interactions. Each pairwise interaction is a long-range interaction, as characterized by a soft oscillatory attenuation (at the power exponent of n  = −1 or −2). The vector additivity of the acoustic interaction force, which is not well expected considering the nonlinear nature of the acoustic radiation force, is greatly useful for exploring a system consisting of a large number of particles. The capability of self-organizing a big particle cluster can be anticipated through such acoustically controllable long-range interaction. (paper)

  7. Drop behavior in acoustic standing waves; Teizaihachu ni okeru ekiteki no kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Kamimura, H. [National Aerospace Laboratory, Tokyo (Japan); Yamanaka, T. [Yokohama National University, Yokohama (Japan)

    1997-10-01

    When new materials, such as those for space shuttles, are developed, it is necessary to hold then in a non-contacting manner. Described herein is behavior of drops in a holding device which utilizes acoustic radiation pressure. When an object sufficiently small as compared with wavelength of a sound wave is placed in acoustic standing waves, it is subjected to acoustic radiation pressure. Chandrasekahr developed the theory on the stability of a rotating drop by equating the entire mechanical energy of a drop with its surface energy. This theory, based on the assumption of symmetric surface energy, is incapable of theoretically dealing with multi-lobed waves evolved by surface tension. In this study, multi-lobed waves excited by sound waves in a rotating drop are analytically found without assuming symmetry of drop surface energy. The multi-lobe waves are first found on the assumption that the acoustic radiation pressure around a drop is constant. Then, the effects of the deformed drop on the radiation pressure around the drop are considered. In addition, the equation for the relationship between the radiation pressure and a drop that becomes oblate due to the radiation pressure is obtained. The theoretically derived results by this equation are in good agreement with the observed results by the ground and flight tests. 17 refs., 18 figs.

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

    Directory of Open Access Journals (Sweden)

    S. S. Ghosh

    2004-01-01

    Full Text Available The presence of dynamic, large amplitude solitary waves in the auroral regions of space is well known. Since their velocities are of the order of the ion acoustic speed, they may well be considered as being generated from the nonlinear evolution of ion acoustic waves. However, they do not show the expected width-amplitude correlation for K-dV solitons. Recent POLAR observations have actually revealed that the low altitude rarefactive ion acoustic solitary waves are associated with an increase in the width with increasing amplitude. This indicates that a weakly nonlinear theory is not appropriate to describe the solitary structures in the auroral regions. In the present work, a fully nonlinear analysis based on Sagdeev pseudopotential technique has been adopted for both parallel and oblique propagation of rarefactive solitary waves in a two electron temperature multi-ion plasma. The large amplitude solutions have consistently shown an increase in the width with increasing amplitude. The width-amplitude variation profile of obliquely propagating rarefactive solitary waves in a magnetized plasma have been compared with the recent POLAR observations. The width-amplitude variation pattern is found to fit well with the analytical results. It indicates that a fully nonlinear theory of ion acoustic solitary waves may well explain the observed anomalous width variations of large amplitude structures in the auroral region.

  9. 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.

  10. Effect of non-Maxwellian particle trapping and dust grain charging on dust acoustic solitary waves

    International Nuclear Information System (INIS)

    Rubab, N.; Murtaza, G.; Mushtaq, A.

    2006-01-01

    The role of adiabatic trapped ions on a small but finite amplitude dust acoustic wave, including the effect of adiabatic dust charge variation, is investigated in an unmagnetized three-component dusty plasma consisting of electrons, ions and massive micron sized negatively charged dust particulates. We have assumed that electrons and ions obey (r,q) velocity distribution while the dust species is treated fluid dynamically. It is found that the dynamics of dust acoustic waves is governed by a modified r dependent Korteweg-de Vries equation. Further, the spectral indices (r,q) affect the charge fluctuation as well as the trapping of electrons and ions and consequently modify the dust acoustic solitary wave

  11. 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.

  12. 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.

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

    Science.gov (United States)

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

    2013-09-03

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

  14. 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.

  15. Ion acoustic waves in pair-ion plasma: Linear and nonlinear analyses

    International Nuclear Information System (INIS)

    Saeed, R.; Mushtaq, A.

    2009-01-01

    Linear and nonlinear properties of low frequency ion acoustic wave (IAW) in pair-ion plasma in the presence of electrons are investigated. The dispersion relation and Kadomtsev-Petviashvili equation for linear/nonlinear IAW are derived from sets of hydrodynamic equations where the ion pairs are inertial while electrons are Boltzmannian. The dispersion curves for various concentrations of electrons are discussed and compared with experimental results. The predicted linear IAW propagates at the same frequencies as those of the experimentally observed IAW if n e0 ∼10 4 cm -3 . It is found that nonlinear profile of the ion acoustic solitary waves is significantly affected by the percentage ratio of electron number density and temperature. It is also determined that rarefactive solitary waves can propagate in this system. It is hoped that the results presented in this study would be helpful in understanding the salient features of the finite amplitude localized ion acoustic solitary pulses in a laboratory fullerene plasma.

  16. Planar and nonplanar ion acoustic shock waves in relativistic degenerate astrophysical electron-positron-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ata-ur-Rahman,; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2013-04-15

    We have studied the propagation of ion acoustic shock waves involving planar and non-planar geometries in an unmagnetized plasma, whose constituents are non-degenerate ultra-cold ions, relativistically degenerate electrons, and positrons. By using the reductive perturbation technique, Korteweg-deVries Burger and modified Korteweg-deVries Burger equations are derived. It is shown that only compressive shock waves can propagate in such a plasma system. The effects of geometry, the ion kinematic viscosity, and the positron concentration are examined on the ion acoustic shock potential and electric field profiles. It is found that the properties of ion acoustic shock waves in a non-planar geometry significantly differ from those in planar geometry. The present study has relevance to the dense plasmas, produced in laboratory (e.g., super-intense laser-dense matter experiments) and in dense astrophysical objects.

  17. Reflection and transformation of acoustic waves at the interface in superfluid 3He-A

    International Nuclear Information System (INIS)

    Kekutiya, Sh.E.; Chkhaidze, N.D.

    1997-01-01

    Reflection and transformation of acoustic waves in 3 He-A and 3 He-A 1 are considered for two cases: (1) at the boundary with a solid impermeable wall at an arbitrary angle of incidence of a wave and (2) for normal incidence of waves on the interface between a free liquid and a system of periodic plane-parallel capillaries filling the semi-space. For the first case we have calculated the reflection coefficients of the first and the second sounds and spin and spin-temperature waves as well as the coefficients of transformation of these waves into each other. It is shown that the longitudinal wave undergoes no transformation into other waves, there occurs instead its complete reflection from the solid wall. The angle of incidence at which the energy attenuation coefficient of the first sound is maximum, and the interval of angles corresponding to the attenuation and the total interval reflection of the second sound are estimated. For the second case we have obtained: the coefficients of excitation of the fourth sound and the magneto-acoustic wave by the first and the second sounds; the reflection coefficients for the first and the second sounds and the longitudinal spin wave; the coefficient of transformation of the first sound into the second one and vice versa; the coefficient of reflection of the fourth sound from the capillary system - free liquid interface; the coefficient of excitation of longitudinal spin wave in free helium by the same wave in a capillary

  18. Acoustic Gravity Waves Generated by an Oscillating Ice Sheet in Arctic Zone

    Science.gov (United States)

    Abdolali, A.; Kadri, U.; Kirby, J. T., Jr.

    2016-12-01

    We investigate the formation of acoustic-gravity waves due to oscillations of large ice blocks, possibly triggered by atmospheric and ocean currents, ice block shrinkage or storms and ice-quakes.For the idealized case of a homogeneous weakly compressible water bounded at the surface by ice sheet and a rigid bed, the description of the infinite family of acoustic modes is characterized by the water depth h and angular frequency of oscillating ice sheet ω ; The acoustic wave field is governed by the leading mode given by: Nmax=\\floor {(ω h)/(π c)} where c is the sound speed in water and the special brackets represent the floor function (Fig1). Unlike the free-surface setting, the higher acoustic modes might exhibit a larger contribution and therefore all progressive acoustic modes have to be considered.This study focuses on the characteristics of acoustic-gravity waves generated by an oscillating elastic ice sheet in a weakly compressible fluid coupled with a free surface model [Abdolali et al. 2015] representing shrinking ice blocks in realistic sea state, where the randomly oriented ice sheets cause inter modal transition and multidirectional reflections. A theoretical solution and a 3D numerical model have been developed for the study purposes. The model is first validated against the theoretical solution [Kadri, 2016]. To overcome the computational difficulties of 3D models, we derive a depth-integrated equation valid for spatially varying ice sheet thickness and water depth. We show that the generated acoustic-gravity waves contribute significantly to deep ocean currents compared to other mechanisms. In addition, these waves travel at the sound speed in water carrying information on ice sheet motion, providing various implications for ocean monitoring and detection of ice-quakes. Fig1:Snapshots of dynamic pressure given by an oscillating ice sheet; h=4500m, c=1500m/s, semi-length b=10km, ζ =1m, omega=π rad/s. Abdolali, A., Kirby, J. T. and Bellotti, G

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Vaivads, A

    1996-04-01

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

  1. 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.

  2. Developing an Acoustic Sensing Yarn for Health Surveillance in a Military Setting

    Directory of Open Access Journals (Sweden)

    Theodore Hughes-Riley

    2018-05-01

    Full Text Available Overexposure to high levels of noise can cause permanent hearing disorders, which have a significant adverse effect on the quality of life of those affected. Injury due to noise can affect people in a variety of careers including construction workers, factory workers, and members of the armed forces. By monitoring the noise exposure of workers, overexposure can be avoided and suitable protective equipment can be provided. This work focused on the creation of a noise dosimeter suitable for use by members of the armed forces, where a discrete dosimeter was integrated into a textile helmet cover. In this way the sensing elements could be incorporated very close to the ears, providing a highly representative indication of the sound level entering the body, and also creating a device that would not interfere with military activities. This was achieved by utilising commercial microelectromechanical system microphones integrated within the fibres of yarn to create an acoustic sensing yarn. The acoustic sensing yarns were fully characterised over a range of relevant sound levels and frequencies at each stage in the yarn production process. The yarns were ultimately integrated into a knitted helmet cover to create a functional acoustic sensing helmet cover prototype.

  3. Localizing Fracture Hydromechanical Response using Fiber Optic Distributed Acoustic Sensing in a Fractured Bedock Aquifer

    Science.gov (United States)

    Ciervo, C.; Becker, M.; Cole, M. C.; Coleman, T.; Mondanos, M.

    2017-12-01

    Measuring fracture mechanical behavior in response to changes in fluid pressure is critical for understanding flow through petroleum reservoirs, predicting hydrothermal responses in geothermal fields, and monitoring geologic carbon sequestration injection. Distributed acoustic sensing (DAS) is new, but commercially available fiber optic technology that offers a novel approach to characterize fractured bedrock systems. DAS was originally designed to measure the amplitude, frequency, and phase of an acoustic wave, and is therefore capable of detecting strains at exceedingly small scales. Though normally used to measure frequencies in the Hz to kHz range, we adapted DAS to measure fracture displacements in response to periodic hydraulic pulses in the mHz frequency range. A field experiment was conducted in a fractured bedrock aquifer to test the ability of DAS to measure fracture mechanical response to oscillatory well tests. Fiber optic cable was deployed in a well, and coupled to the borehole wall using a flexible impermeable liner designed with an air coupled transducer to measure fluid pressure at the target fracture zone. Two types of cable were tested, a loose tube and tight buffered, to determine the effects of cable construction. Both strain and pressure were measured across the known fracture zone hydraulically connected to a well 30 m away. The companion well was subjected to alternating pumping and injection with periods between 2 and 18 minutes. Raw DAS data were collected as strain rate measured every 0.25 m along the fiber with a gauge length of 10 m, at a sampling rate of 1 kHz. Strain rate was converted to strain by integrating with respect to time. DAS measured periodic strains of less than 1 nm/m in response to periodic injection and pumping at the companion well. Strain was observed by DAS only at the depth of the hydraulically connected fracture zone. Thus, the magnitude and response of the strain could be both localized with depth and measured

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

    International Nuclear Information System (INIS)

    Pogorel'tsev, A.I.; Bidlingmajer, E.R.

    1992-01-01

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

  5. 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.

  6. Design of Passive Acoustic Wave Shaping Devices and Their Experimental Validation

    DEFF Research Database (Denmark)

    Christiansen, Rasmus Ellebæk; Sigmund, Ole; Fernandez Grande, Efren

    We discuss a topology optimization based approach for designing passive acoustic wave shaping devices and demonstrate its application to; directional sound emission [1], sound focusing and wave splitting. Optimized devices, numerical and experimental results are presented and benchmarked against...... other designs proposed in the literature. We focus on design problems where the size of the device is on the order of the wavelength, a problematic region for traditional design methods, such as ray tracing.The acoustic optimization problem is formulated in the frequency domain and modeled...

  7. Control of the long period grating spectrum through low frequency flexural acoustic waves

    International Nuclear Information System (INIS)

    Oliveira, Roberson A; Possetti, Gustavo R C; Kamikawachi, Ricardo C; Fabris, José L; Muller, Marcia; Pohl, Alexandre A P; Marques, Carlos A F; Nogueira, Rogério N; Neves, Paulo T Jr; Cook, Kevin; Canning, John; Bavastri, C

    2011-01-01

    We have shown experimental results of the excitation of long period fiber gratings by means of flexural acoustic waves with a wavelength larger than the grating period, validated by numerical simulations. The effect of the acoustic wave on the grating is modeled with the method of assumed modes, which delivers the strain field inside the grating, then used as the input to the transfer matrix method, needed for calculating the grating spectrum. The experimental and numerical results are found to be in good agreement, even though only the strain-optic effects are taken into account

  8. The dust acoustic wave in a bounded dusty plasma with strong electrostatic interactions between dust grains

    International Nuclear Information System (INIS)

    Shukla, Nitin; Shukla, P.K.

    2011-01-01

    The dispersion relation for the dust acoustic wave (DAW) in an unmagnetized dusty plasma cylindrical waveguide is derived, accounting for strong electrostatic interactions between charged dust grains. It is found that the boundary effect limits the radial extent of the DAW. The present result should be helpful for understanding the frequency spectrum of the DAW in a dusty plasma waveguide with strongly coupled charged dust grains. - Highlights: → We study the dust acoustic wave (DAW) in a bounded plasma. → We account for interactions between dust grains. → The boundary effect limits the radial extent of the DAW.

  9. A surface acoustic wave sensor functionalized with a polypyrrole molecularly imprinted polymer for selective dopamine detection.

    Science.gov (United States)

    Maouche, Naima; Ktari, Nadia; Bakas, Idriss; Fourati, Najla; Zerrouki, Chouki; Seydou, Mahamadou; Maurel, François; Chehimi, Mohammed Mehdi

    2015-11-01

    A surface acoustic wave sensor operating at 104 MHz and functionalized with a polypyrrole molecularly imprinted polymer has been designed for selective detection of dopamine (DA). Optimization of pyrrole/DA ratio, polymerization and immersion times permitted to obtain a highly selective sensor, which has a sensitivity of 0.55°/mM (≈ 550 Hz/mM) and a detection limit of ≈ 10 nM. Morphology and related roughness parameters of molecularly imprinted polymer surfaces, before and after extraction of DA, as well as that of the non imprinted polymer were characterized by atomic force microscopy. The developed chemosensor selectively recognized dopamine over the structurally similar compound 4-hydroxyphenethylamine (referred as tyramine), or ascorbic acid,which co-exists with DA in body fluids at a much higher concentration. Selectivity tests were also carried out with dihydroxybenzene, for which an unexpected phase variation of order of 75% of the DA one was observed. Quantum chemical calculations, based on the density functional theory, were carried out to determine the nature of interactions between each analyte and the PPy matrix and the DA imprinted PPy polypyrrole sensing layer in order to account for the important phase variation observed during dihydroxybenzene injection. Copyright © 2015 John Wiley & Sons, Ltd.

  10. Temperature dependence of immunoreactions using shear horizontal surface acoustic wave immunosensors

    Science.gov (United States)

    Kogai, Takashi; Yatsuda, Hiromi; Kondoh, Jun

    2017-07-01

    In this paper, the temperature dependence of immunoreactions, which are antibody-antigen reactions, on a shear horizontal surface acoustic wave (SH-SAW) immunosensor is described. The immunosensor is based on a reflection-type delay line on a 36° Y-cut 90° X-propagation quartz substrate, where the delay line is composed of a floating electrode unidirectional transducer (FEUDT), a grating reflector, and a sensing area between them. In order to evaluate the temperature dependence of immunoreactions, human serum albumin (HSA) antigen-antibody reactions are investigated. The SH-SAW immunosensor chip is placed in a thermostatic chamber and the changes in the SH-SAW velocity resulting from the immunoreactions are measured at different temperatures. As a result, it is observed that the HSA immunoreactions are influenced by the ambient temperature and that higher temperatures provide more active reactions. In order to analyze the immunoreactions, an analytical approach using an exponential fitting method for changes in SH-SAW velocity is employed.

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

    Science.gov (United States)

    Deryabin, M. S.; Kasyanov, D. A.; Kurin, V. V.; Garasyov, M. A.

    2016-05-01

    We show that a significant energy redistribution occurs in the spectrum of reflected nonlinear waves, when an intense acoustic beam is reflected from an acoustically soft boundary, which manifests itself at short wave distances from a reflecting boundary. This effect leads to the appearance of extrema in the distributions of the amplitude and intensity of the field of the reflected acoustic beam near the reflecting boundary. The results of physical experiments are confirmed by numerical modeling of the process of transformation of nonlinear waves reflected from an acoustically soft boundary. Numerical modeling was performed by means of the Khokhlov—Zabolotskaya—Kuznetsov (KZK) equation.

  12. Propagation of acoustic-gravity waves in arctic zones with elastic ice-sheets

    Science.gov (United States)

    Kadri, Usama; Abdolali, Ali; Kirby, James T.

    2017-04-01

    We present an analytical solution of the boundary value problem of propagating acoustic-gravity waves generated in the ocean by earthquakes or ice-quakes in arctic zones. At the surface, we assume elastic ice-sheets of a variable thickness, and show that the propagating acoustic-gravity modes have different mode shape than originally derived by Ref. [1] for a rigid ice-sheet settings. Computationally, we couple the ice-sheet problem with the free surface model by Ref. [2] representing shrinking ice blocks in realistic sea state, where the randomly oriented ice-sheets cause inter modal transition at the edges and multidirectional reflections. We then derive a depth-integrated equation valid for spatially slowly varying thickness of ice-sheet and water depth. Surprisingly, and unlike the free-surface setting, here it is found that the higher acoustic-gravity modes exhibit a larger contribution. These modes travel at the speed of sound in water carrying information on their source, e.g. ice-sheet motion or submarine earthquake, providing various implications for ocean monitoring and detection of quakes. In addition, we found that the propagating acoustic-gravity modes can result in orbital displacements of fluid parcels sufficiently high that may contribute to deep ocean currents and circulation, as postulated by Refs. [1, 3]. References [1] U. Kadri, 2016. Generation of Hydroacoustic Waves by an Oscillating Ice Block in Arctic Zones. Advances in Acoustics and Vibration, 2016, Article ID 8076108, 7 pages http://dx.doi.org/10.1155/2016/8076108 [2] A. Abdolali, J. T. Kirby and G. Bellotti, 2015, Depth-integrated equation for hydro-acoustic waves with bottom damping, J. Fluid Mech., 766, R1 doi:10.1017/jfm.2015.37 [3] U. Kadri, 2014. Deep ocean water transportation by acoustic?gravity waves. J. Geophys. Res. Oceans, 119, doi:10.1002/ 2014JC010234

  13. Two-dimensional numerical simulation of acoustic wave phase conjugation in magnetostrictive elastic media

    Science.gov (United States)

    Voinovich, Peter; Merlen, Alain

    2005-12-01

    The effect of parametric wave phase conjugation (WPC) in application to ultrasound or acoustic waves in magnetostrictive solids has been addressed numerically by Ben Khelil et al. [J. Acoust. Soc. Am. 109, 75-83 (2001)] using 1-D unsteady formulation. Here the numerical method presented by Voinovich et al. [Shock waves 13(3), 221-230 (2003)] extends the analysis to the 2-D effects. The employed model describes universally elastic solids and liquids. A source term similar to Ben Khelil et al.'s accounts for the coupling between deformation and magnetostriction due to external periodic magnetic field. The compatibility between the isotropic constitutive law of the medium and the model of magnetostriction has been considered. Supplementary to the 1-D simulations, the present model involves longitudinal/transversal mode conversion at the sample boundaries and separate magnetic field coupling with dilatation and shear stress. The influence of those factors in a 2-D geometry on the potential output of a magneto-elastic wave phase conjugator is analyzed in this paper. The process under study includes propagation of a wave burst of a given frequency from a point source in a liquid into the active solid, amplification of the waves due to parametric resonance, and formation of time-reversed waves, their radiation into liquid, and focusing. The considered subject is particularly important for ultrasonic applications in acoustic imaging, nondestructive testing, or medical diagnostics and therapy.

  14. Acoustic waves and the detectability of first-order phase transitions by eLISA

    Science.gov (United States)

    Weir, David J.

    2017-05-01

    In various extensions of the Standard Model it is possible that the electroweak phase transition was first order. This would have been a violent process, involving the formation of bubbles and associated shock waves. Not only would the collision of these bubbles and shock waves be a detectable source of gravitational waves, but persistent acoustic waves could enhance the signal and improve prospects of detection by eLISA. I summarise the results of a recent campaign to model such a phase transition based on large-scale hydrodynamical simulations, and its implications for the eLISA mission.

  15. Surface acoustic wave devices on AlN/3C–SiC/Si multilayer structures

    International Nuclear Information System (INIS)

    Lin, Chih-Ming; Lien, Wei-Cheng; Riekkinen, Tommi; Senesky, Debbie G; Pisano, Albert P; Chen, Yung-Yu; Felmetsger, Valery V

    2013-01-01

    Surface acoustic wave (SAW) propagation characteristics in a multilayer structure including a piezoelectric aluminum nitride (AlN) thin film and an epitaxial cubic silicon carbide (3C–SiC) layer on a silicon (Si) substrate are investigated by theoretical calculation in this work. Alternating current (ac) reactive magnetron sputtering was used to deposit highly c-axis-oriented AlN thin films, showing the full width at half maximum (FWHM) of the rocking curve of 1.36° on epitaxial 3C–SiC layers on Si substrates. In addition, conventional two-port SAW devices were fabricated on the AlN/3C–SiC/Si multilayer structure and SAW propagation properties in the multilayer structure were experimentally investigated. The surface wave in the AlN/3C–SiC/Si multilayer structure exhibits a phase velocity of 5528 m s −1 and an electromechanical coupling coefficient of 0.42%. The results demonstrate the potential of AlN thin films grown on epitaxial 3C–SiC layers to create layered SAW devices with higher phase velocities and larger electromechanical coupling coefficients than SAW devices on an AlN/Si multilayer structure. Moreover, the FWHM values of rocking curves of the AlN thin film and 3C–SiC layer remained constant after annealing for 500 h at 540 °C in air atmosphere. Accordingly, the layered SAW devices based on AlN thin films and 3C–SiC layers are applicable to timing and sensing applications in harsh environments. (paper)

  16. Comparision of Bathymetry and Bottom Characteristics From Hyperspectral Remote Sensing Data and Shipborne Acoustic Measurements

    Science.gov (United States)

    McIntyre, M. L.; Naar, D. F.; Carder, K. L.; Howd, P. A.; Lewis, J. M.; Donahue, B. T.; Chen, F. R.

    2002-12-01

    There is growing interest in applying optical remote sensing techniques to shallow-water geological applications such as bathymetry and bottom characterization. Model inversions of hyperspectral remote-sensing reflectance imagery can provide estimates of bottom albedo and depth. This research was conducted in support of the HyCODE (Hyperspectral Coupled Ocean Dynamics Experiment) project in order to test optical sensor performance and the use of a hyperspectral remote-sensing reflectance algorithm for shallow waters in estimating bottom depths and reflectance. The objective of this project was to compare optically derived products of bottom depths and reflectance to shipborne acoustic measurements of bathymetry and backscatter. A set of three high-resolution, multibeam surveys within an 18 km by 1.5 km shore-perpendicular transect 5 km offshore of Sarasota, Florida were collected at water depths ranging from 8 m to 16 m. These products are compared to bottom depths derived from aircraft remote-sensing data collected with the AVIRIS (Airborne Visible-Infrared Imaging Spectrometer) instrument data by means of a semi-analytical remote sensing reflectance model. The pixel size of the multibeam bathymetry and AVIRIS data are 0.25 m and 10 m, respectively. When viewed at full resolution, the multibeam bathymetry data show small-scale sedimentary bedforms (wavelength ~10m, amplitude ~1m) that are not observed in the lower resolution hyperspectral bathymetry. However, model-derived bottom depths agree well with a smoothed version of the multibeam bathymetry. Depths derived from shipborne hyperspectral measurements were accurate within 13%. In areas where diver observations confirmed biological growth and bioturbation, derived bottom depths were less accurate. Acoustic backscatter corresponds well with the aircraft hyperspectral imagery and in situ measurements of bottom reflectance. Acoustic backscatter was used to define the distribution of different bottom types

  17. Remote sensing of temperature and wind using acoustic travel-time measurements

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Manuela; Fischer, Gabi; Raabe, Armin; Weisse, Frank [Leipzig Univ. (Germany). Inst. fuer Meteorologie; Ziemann, Astrid [Technische Univ. Dresden (Germany). Professur fuer Meteorologie

    2013-04-15

    A remote sensing technique to detect area-averaged temperature and flow properties within an area under investigation, utilizing acoustic travel-time measurements, is introduced. This technique uses the dependency of the speed of acoustic signals on the meteorological parameters temperature and wind along the propagation path. The method itself is scalable: It is applicable for investigation areas with an extent of some hundred square metres as well as for small-scale areas in the range of one square metre. Moreover, an arrangement of the acoustic transducers at several height levels makes it possible to determine profiles and gradients of the meteorological quantities. With the help of two examples the potential of this remote sensing technique for simultaneously measuring averaged temperature and flow fields is demonstrated. A comparison of time histories of temperature and wind values derived from acoustic travel-time measurements with point measurements shows a qualitative agreement whereas calculated root-mean-square errors differ for the two example applications. They amount to 1.4 K and 0.3 m/s for transducer distances of 60 m and 0.4 K and 0.2 m/s for transducer distances in the range of one metre. (orig.)

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

    Science.gov (United States)

    Gusev, Vitalyi E; Ni, Chenyin; Lomonosov, Alexey; Shen, Zhonghua

    2015-08-01

    Theory accounting for the influence of hysteretic nonlinearity of micro-inhomogeneous material on flexural wave in the plates of continuously varying thickness is developed. For the wedges with thickness increasing as a power law of distance from its edge strong modifications of the wave dynamics with propagation distance are predicted. It is found that nonlinear absorption progressively disappearing with diminishing wave amplitude leads to complete attenuation of acoustic waves in most of the wedges exhibiting black hole phenomenon. It is also demonstrated that black holes exist beyond the geometrical acoustic approximation. Applications include nondestructive evaluation of micro-inhomogeneous materials and vibrations damping. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. 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...

  20. Three-dimensional continuous particle focusing in a microfluidic channel via standing surface acoustic waves (SSAW).

    Science.gov (United States)

    Shi, Jinjie; Yazdi, Shahrzad; Lin, Sz-Chin Steven; Ding, Xiaoyun; Chiang, I-Kao; Sharp, Kendra; Huang, Tony Jun

    2011-07-21

    Three-dimensional (3D) continuous microparticle focusing has been achieved in a single-layer polydimethylsiloxane (PDMS) microfluidic channel using a standing surface acoustic wave (SSAW). The SSAW was generated by the interference of two identical surface acoustic waves (SAWs) created by two parallel interdigital transducers (IDTs) on a piezoelectric substrate with a microchannel precisely bonded between them. To understand the working principle of the SSAW-based 3D focusing and investigate the position of the focal point, we computed longitudinal waves, generated by the SAWs and radiated into the fluid media from opposite sides of the microchannel, and the resultant pressure and velocity fields due to the interference and reflection of the longitudinal waves. Simulation results predict the existence of a focusing point which is in good agreement with our experimental observations. Compared with other 3D focusing techniques, this method is non-invasive, robust, energy-efficient, easy to implement, and applicable to nearly all types of microparticles.

  1. Asymmetric transmission of acoustic waves in a layer thickness distribution gradient structure using metamaterials

    Directory of Open Access Journals (Sweden)

    Jung-San Chen

    2016-09-01

    Full Text Available This research presents an innovative asymmetric transmission design using alternate layers of water and metamaterial with complex mass density. The directional transmission behavior of acoustic waves is observed numerically inside the composite structure with gradient layer thickness distribution and the rectifying performance of the present design is evaluated. The layer thickness distributions with arithmetic and geometric gradients are considered and the effect of gradient thickness on asymmetric wave propagation is systematically investigated using finite element simulation. The numerical results indicate that the maximum pressure density and transmission through the proposed structure are significantly influenced by the wave propagation direction over a wide range of audible frequencies. Tailoring the thickness of the layered structure enables the manipulation of asymmetric wave propagation within the desired frequency range. In conclusion, the proposed design offers a new possibility for developing directional-dependent acoustic devices.

  2. The Ion Acoustic Solitary Waves and Double Layers in the Solar Wind Plasma

    Directory of Open Access Journals (Sweden)

    C. R. Choi

    2006-09-01

    Full Text Available Ion acoustic solitary wave in a plasma consisting of electrons and ions with an external magnetic field is reinvestigated using the Sagdeev's potential method. Although the Sagdeev potential has a singularity for n<1, where n is the ion number density, we obtain new solitary wave solutions by expanding the Sagdeev potential up to δ n^4 near n=1. They are compressiv (rarefactive waves and shock type solitary waves. These waves can exist all together as a superposed wave which may be used to explain what would be observed in the solar wind plasma. We compared our theoretical results with the data of the Freja satellite in the study of Wu et al.(1996. Also it is shown that these solitary waves propagate with a subsonic speed.

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

    International Nuclear Information System (INIS)

    Desjouy, C.; Ollivier, S.; Dragna, D.; Blanc-Benon, P.; Marsden, O.

    2015-01-01

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

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

    Science.gov (United States)

    Sokolova, Inna

    2015-04-01

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

  6. Locating the Tohoku-Oki 2011 tsunami source using acoustic-gravity waves

    OpenAIRE

    Andriamiranto Raveloson; Rainer Kind; Xiaohui Yuan; L. Cerana

    2012-01-01

    The giant Tohoku-Oki earthquake of 11 March 2011 in offshore Japan did not only generate tsunami waves in the ocean but also infrasound (or acoustic-gravity) waves in the atmosphere. We indentified ultra-long-period signals (>500s) in the recordings of infrasound stations in northeast Asia, the northwest Pacific, and Alaska. Their source was fond close to the earthquake epicenter. Therefore, we conclude that in general, infrasound observations after a large offshore earthquake are evidence th...

  7. Nonlinear localized dust acoustic waves in a charge varying dusty plasma with nonthermal ions

    International Nuclear Information System (INIS)

    Tribeche, Mouloud; Amour, Rabia

    2007-01-01

    A numerical investigation is presented to show the existence, formation, and possible realization of large-amplitude dust acoustic (DA) solitary waves in a charge varying dusty plasma with nonthermal ions. These nonlinear localized structures are self-consistent solutions of the collisionless Vlasov equation with a population of fast particles. The spatial patterns of the variable charge DA solitary wave are significantly modified by the nonthermal effects. The results complement and provide new insights into previously published results on this problem

  8. Compensation of shear waves in photoacoustic tomography with layered acoustic media.

    Science.gov (United States)

    Schoonover, Robert W; Anastasio, Mark A

    2011-10-01

    An image reconstruction formula is presented for photoacoustic computed tomography that accounts for conversion between longitudinal and shear waves in a planar-layered acoustic medium. We assume the optical absorber that produces the photoacoustic wave field is embedded in a single fluid layer and any elastic solid layers present are separated by one or more fluid layers. The measurement aperture is assumed to be planar. Computer simulation studies are conducted to demonstrate and investigate the proposed reconstruction formula.

  9. Introduction to the physics properties of the waves trough the sound and acoustic didactics

    OpenAIRE

    Bernad Martínez, Jordi

    2017-01-01

    The project makes a journey through sound and acoustics to introduce abstract concepts related with the properties of waves, its processing and acquisition, digitization and compression. Develop a portfolio of basic theory adapted to students, which provides support for practices in order to consolidate and assimilate concepts related to the world of waves and communication. The project aims to link the content with situations or activities related to daily experiences of young students. Curr...

  10. Acoustic Wave in a Dusty Plasma with Frequent Grain Charging Collisions

    International Nuclear Information System (INIS)

    Lee, Hee J.; Cho, Sang-Hoon

    2003-01-01

    The sink terms in the electron and ion continuity equations and the frictional terms in the momentum equations of a dusty plasma are obtained by taking moments of a kinetic equation which takes into account the grain charging collisions by electrons and ions. We show that an acoustic wave can propagate as a normal mode in the parameter regime where the frequencies of charging collisions are much greater than the wave frequency

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

    International Nuclear Information System (INIS)

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

    1979-01-01

    This paper presents an investigation of solar wind ion acoustic waves and their relationship to the macroscopic and microscopic characteristics of the solar wind plasma. Comparisons with the overall solar wind corotational structure show that the most intense ion acoustic waves usually occur in the low-velocity regions ahead of high-speed solar wind streams. Of the detailed plasma parameters investigated, the ion acoustic wave intensities are found to be most closely correlated with the electron to proton temperature ratio T/sub e//T/sub p/ and with the electron heat flux. Investigations of the detailed electron and proton distribution functions also show that the ion acoustic waves usually occur in regions with highly non-Maxwellian distributions characteristic of double-proton streams. The distribution functions for the double-proton streams are usually not resolved into two clearly defined peaks, but rather they appear as a broad shoulder on the main proton distribution. Two main mechanisms, an electron heat flux instability and a double-ion beam instability, are considered for generating the ion-acoustic-like waves observed in the solar wind. Both mechanisms have favorable and unfavorable features. The electron heat flux mechanism can account for the observed waves at moderate to large ratios of T/sub e//T/sub p/ but has problems when T/sub e//T/sub p/ is small, as sometimes occurs. The ion beam instability appears to provide more flexibility on the T/sub e//T/sub p/ ratio; however detailed comparisons using observed distribution functions indicate that the ion beam mode is usually stable. Possible resolutions of these difficulties are discussed

  12. Effects of positron density and temperature on large amplitude ion-acoustic waves in an electron-positron-ion plasma

    International Nuclear Information System (INIS)

    Nejoh, Y.N.

    1997-01-01

    The nonlinear wave structures of large amplitude ion-acoustic waves are studied in a plasma with positrons. We have presented the region of existence of the ion-acoustic waves by analysing the structure of the pseudopotential. The region of existence sensitively depends on the positron to electron density ratio, the ion to electron mass ratio and the positron to electron temperature ratio. It is shown that the maximum Mach number increases as the positron temperature increases and the region of existence of the ion-acoustic waves spreads as the positron temperature increases. 12 refs., 6 figs

  13. 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.

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

    Science.gov (United States)

    Zhu, Hongfei; Semperlotti, Fabio

    2016-07-15

    The concept of a metasurface opens new exciting directions to engineer the refraction properties in both optical and acoustic media. Metasurfaces are typically designed by assembling arrays of subwavelength anisotropic scatterers able to mold incoming wave fronts in rather unconventional ways. The concept of a metasurface was pioneered in photonics and later extended to acoustics while its application to the propagation of elastic waves in solids is still relatively unexplored. We investigate the design of acoustic metasurfaces to control elastic guided waves in thin-walled structural elements. These engineered discontinuities enable the anomalous refraction of guided wave modes according to the generalized Snell's law. The metasurfaces are made out of locally resonant toruslike tapers enabling an accurate phase shift of the incoming wave, which ultimately affects the refraction properties. We show that anomalous refraction can be achieved on transmitted antisymmetric modes (A_{0}) either when using a symmetric (S_{0}) or antisymmetric (A_{0}) incident wave, the former clearly involving mode conversion. The same metasurface design also allows achieving structure embedded planar focal lenses and phase masks for nonparaxial propagation.

  15. MEASUREMENTS OF ABSORPTION, EMISSIVITY REDUCTION, AND LOCAL SUPPRESSION OF SOLAR ACOUSTIC WAVES IN SUNSPOTS

    International Nuclear Information System (INIS)

    Chou, D.-Y.; Liang, Z.-C.; Yang, M.-H.; Zhao Hui; Sun, M.-T.

    2009-01-01

    The power of solar acoustic waves in magnetic regions is lower relative to the quiet Sun. Absorption, emissivity reduction, and local suppression of acoustic waves contribute to the observed power reduction in magnetic regions. We propose a model for the energy budget of acoustic waves propagating through a sunspot in terms of the coefficients of absorption, emissivity reduction, and local suppression of the sunspot. Using the property that the waves emitted along the wave path between two points have no correlation with the signal at the starting point, we can separate the effects of these three mechanisms. Applying this method to helioseismic data filtered with direction and phase-velocity filters, we measure the fraction of the contribution of each mechanism to the power deficit in the umbra of the leading sunspot of NOAA 9057. The contribution from absorption is 23.3 ± 1.3%, emissivity reduction 8.2 ± 1.4%, and local suppression 68.5 ± 1.5%, for a wave packet corresponding to a phase velocity of 6.98 x 10 -5 rad s -1 .

  16. Horizontal Acoustic Barriers for Protection from Seismic Waves

    Directory of Open Access Journals (Sweden)

    Sergey V. Kuznetsov

    2011-01-01

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

  17. The formation and dissipation of electrostatic shock waves: the role of ion–ion acoustic instabilities

    Science.gov (United States)

    Zhang, Wen-shuai; Cai, Hong-bo; Zhu, Shao-ping

    2018-05-01

    The role of ion–ion acoustic instabilities in the formation and dissipation of collisionless electrostatic shock waves driven by counter-streaming supersonic plasma flows has been investigated via two-dimensional particle-in-cell simulations. The nonlinear evolution of unstable waves and ion velocity distributions has been analyzed in detail. It is found that for electrostatic shocks driven by moderate-velocity flows, longitudinal and oblique ion–ion acoustic instabilities can be excited in the downstream and upstream regions, which lead to thermalization of the transmitted and reflected ions, respectively. For high-velocity flows, oblique ion–ion acoustic instabilities can develop in the overlap layer during the shock formation process and impede the shock formation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Greenhall, J.; Raeymaekers, B., E-mail: bart.raeymaekers@utah.edu [Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Guevara Vasquez, F. [Department of Mathematics, University of Utah, Salt Lake City, Utah 84112 (United States)

    2014-10-06

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

  19. 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.

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

    Science.gov (United States)

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

    2016-03-23

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

  1. Acoustic wave simulation using an overset grid for the global monitoring system

    Science.gov (United States)

    Kushida, N.; Le Bras, R.

    2017-12-01

    The International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has been monitoring hydro-acoustic and infrasound waves over the globe. Because of the complex natures of the oceans and the atmosphere, computer simulation can play an important role in understanding the observed signals. In this regard, methods which depend on partial differential equations and require minimum modelling, are preferable. So far, to our best knowledge, acoustic wave propagation simulations based on partial differential equations on such a large scale have not been performed (pp 147 - 161 of ref [1], [2]). The main difficulties in building such simulation codes are: (1) considering the inhomogeneity of medium including background flows, (2) high aspect ratio of computational domain, (3) stability during long time integration. To overcome these difficulties, we employ a two-dimensional finite different (FDM) scheme on spherical coordinates with the Yin-Yang overset grid[3] solving the governing equation of acoustic waves introduces by Ostashev et. al.[4]. The comparison with real recording examples in hydro-acoustic will be presented at the conference. [1] Paul C. Etter: Underwater Acoustic Modeling and Simulation, Fourth Edition, CRC Press, 2013. [2] LIAN WANG et. al.: REVIEW OF UNDERWATER ACOUSTIC PROPAGATION MODELS, NPL Report AC 12, 2014. [3] A. Kageyama and T. Sato: "Yin-Yang grid": An overset grid in spherical geometry, Geochem. Geophys. Geosyst., 5, Q09005, 2004. [4] Vladimir E. Ostashev et. al: Equations for finite-difference, time-domain simulation of sound propagation in moving inhomogeneous media and numerical implementation, Acoustical Society of America. DOI: 10.1121/1.1841531, 2005.

  2. Propagation of dust-acoustic waves in weakly ionized plasmas with ...

    Indian Academy of Sciences (India)

    63, No. 5. — journal of. November 2004 physics pp. 1021–1030. Propagation of dust-acoustic waves in weakly ionized plasmas with dust-charge fluctuation∗. K K MONDAL. Department of Physics ... has essentially to be considered because inertia is provided by the mass of the dust particles. Moreover, the phase velocity ...

  3. In situ characterization of local elastic properties of thin shape memory films by surface acoustic waves

    Czech Academy of Sciences Publication Activity Database

    Grabec, T.; Sedlák, Petr; Stoklasová, Pavla; Thomasová, M.; Shilo, D.; Kabla, M.; Seiner, Hanuš; Landa, Michal

    2016-01-01

    Roč. 25, č. 12 (2016), č. článku 127002. ISSN 0964-1726 R&D Projects: GA ČR GA14-15264S Institutional support: RVO:61388998 Keywords : thin films * shape memory alloys * surface acoustic waves Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.909, year: 2016

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

    International Nuclear Information System (INIS)

    Aramyan, A.R.

    2003-01-01

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

  5. 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...

  6. 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

  7. 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...

  8. Reflection and transmission of ion acoustic waves from a plasma discontinuity

    International Nuclear Information System (INIS)

    Gary, S.P.; Alexeff, I.; Bloomberg, H.W.

    1975-01-01

    Transmission and reflection coefficients are calculated for an ion acoustic wave incident from the upstream direction upon a plasma discontinuity of width much less than the wavelength. In the limit of an infinitely strong discontinuity there is complete in phase reflection. (U.S.)

  9. Nonlinear generation of zonal flows by ion-acoustic waves in a uniform magnetoplasma

    International Nuclear Information System (INIS)

    Shukla, Nitin; Shukla, P.K.

    2010-01-01

    It is shown that large-scale zonal flows (ZFs) can be excited by Reynolds stress of nonlinearly interacting random phase ion-acoustic waves (EIAWs) in a uniform magnetoplasma. Since ZFs are associated with poloidal sheared flows, they can tear apart short scale EIAW turbulence eddies, and hence contribute to the reduction of the cross-field turbulent transport in a magnetized plasma.

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

    Science.gov (United States)

    Rostafinski, W.

    1974-01-01

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

  11. Note: surface acoustic wave resonators for detecting of small changes of temperature: a thermometric "magnifying glass".

    Science.gov (United States)

    Kryshtal, R G; Medved, A V

    2014-02-01

    Application of surface acoustic wave resonators with a phase format of an output signal as the thermometric "magnifying glass" is suggested. Possibilities of monitoring and measuring of small changes of temperature from 0.001 K to 0.3 K of objects having thermal contact with the resonator's substrate are shown experimentally.

  12. 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...

  13. Calculation of the radiation force on a cylinder in a standing wave acoustic field

    Energy Technology Data Exchange (ETDEWEB)

    Haydock, David [Unilever R and D Colworth, Sharnbrook, Bedford MK44 1LQ (United Kingdom); Department of Physics, Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

    2005-04-15

    We present a new calculation of the radiation force on a cylinder in a standing wave acoustic field. We use the formula to calculate the force on a cylinder which is free to move in the field and one which is fixed in space.

  14. Calculation of the radiation force on a cylinder in a standing wave acoustic field

    International Nuclear Information System (INIS)

    Haydock, David

    2005-01-01

    We present a new calculation of the radiation force on a cylinder in a standing wave acoustic field. We use the formula to calculate the force on a cylinder which is free to move in the field and one which is fixed in space

  15. Dust acoustic waves in a dc glow-discharge plasma

    International Nuclear Information System (INIS)

    Molotkov, V.I.; Nefedov, A.P.; Torchinskii, V.M.; Fortov, V.E.; Khrapak, A.G.

    1999-01-01

    The spontaneous excitation of low-frequency oscillations of the macroparticle density in ordered dust structures levitating in standing striations of a dc glow discharge is discovered. It is concluded on the basis of a simplified linear model of an ideal collisionless plasma that the observed instability is caused by the drift motion of ions relative to the dust, which leads to the excitation of dust acoustic oscillations of the plasma

  16. Acoustic Devices for Particle and Cell Manipulation and Sensing

    Directory of Open Access Journals (Sweden)

    Yongqiang Qiu

    2014-08-01

    Full Text Available An emerging demand for the precise manipulation of cells and particles for applications in cell biology and analytical chemistry has driven rapid development of ultrasonic manipulation technology. Compared to the other manipulation technologies, such as magnetic tweezing, dielectrophoresis and optical tweezing, ultrasonic manipulation has shown potential in a variety of applications, with its advantages of versatile, inexpensive and easy integration into microfluidic systems, maintenance of cell viability, and generation of sufficient forces to handle particles, cells and their agglomerates. This article briefly reviews current practice and reports our development of various ultrasonic standing wave manipulation devices, including simple devices integrated with high frequency (>20 MHz ultrasonic transducers for the investigation of biological cells and complex ultrasonic transducer array systems to explore the feasibility of electronically controlled 2-D and 3-D manipulation. Piezoelectric and passive materials, fabrication techniques, characterization methods and possible applications are discussed. The behavior and performance of the devices have been investigated and predicted with computer simulations, and verified experimentally. Issues met during development are highlighted and discussed. To assist long term practical adoption, approaches to low-cost, wafer level batch-production and commercialization potential are also addressed.

  17. A high-order discontinuous Galerkin method for wave propagation through coupled elastic-acoustic media

    International Nuclear Information System (INIS)

    Wilcox, Lucas C.; Stadler, Georg; Burstedde, Carsten; Ghattas, Omar

    2010-01-01

    We introduce a high-order discontinuous Galerkin (dG) scheme for the numerical solution of three-dimensional (3D) wave propagation problems in coupled elastic-acoustic media. A velocity-strain formulation is used, which allows for the solution of the acoustic and elastic wave equations within the same unified framework. Careful attention is directed at the derivation of a numerical flux that preserves high-order accuracy in the presence of material discontinuities, including elastic-acoustic interfaces. Explicit expressions for the 3D upwind numerical flux, derived as an exact solution for the relevant Riemann problem, are provided. The method supports h-non-conforming meshes, which are particularly effective at allowing local adaptation of the mesh size to resolve strong contrasts in the local wavelength, as well as dynamic adaptivity to track solution features. The use of high-order elements controls numerical dispersion, enabling propagation over many wave periods. We prove consistency and stability of the proposed dG scheme. To study the numerical accuracy and convergence of the proposed method, we compare against analytical solutions for wave propagation problems with interfaces, including Rayleigh, Lamb, Scholte, and Stoneley waves as well as plane waves impinging on an elastic-acoustic interface. Spectral rates of convergence are demonstrated for these problems, which include a non-conforming mesh case. Finally, we present scalability results for a parallel implementation of the proposed high-order dG scheme for large-scale seismic wave propagation in a simplified earth model, demonstrating high parallel efficiency for strong scaling to the full size of the Jaguar Cray XT5 supercomputer.

  18. Physics of the ion acoustic wave driven by the stimulated Brillouin scattering instability

    International Nuclear Information System (INIS)

    Clayton, C.E.

    1984-01-01

    The ion acoustic wave excited in the stimulated Brillouin scattering (SBS) instability is probed via collective ruby-laser Thomson scattering in order to understand the low saturation level observed in the instability. Many of the features observed in the Brillouin backscattered CO 2 laser light from the underdense gas-target plasma are also observed in the Thomson scattered ruby light - from which it is learned that the ion acoustic wave grows exponentially and then saturates as the CO 2 pump power is increased. The primary advantage of the ruby Thomson scattering diagnostic is in its capability of providing simultaneous space and time resolved measurements of the ion wave amplitude. From these first such detailed measurements, it was found that the ion wave grows exponentially in space at a rate that agrees with the linear convective SBS theory. However, at higher pump powers, the ion wave saturates at an inferred amplitude of anti-n/n 0 approx. = 5 to 10%. Further increases in the pump power appear to result in an increase in the length over which the ion wave is saturated. A nearly constant SBS reflectivity in this saturated regime, however, suggests that the saturated ion wave does not contribute as much to the scattered power as would be expected from Bragg scattering theory. This apparent contradiction can be resolved if ion trapping is responsible for the saturation of the ion wave

  19. Ion-acoustic cnoidal wave and associated non-linear ion flux in dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jain, S. L. [Poornima Group of Institution, Sitapura, Jaipur 302022 (India); Tiwari, R. S. [Regional College for Education, Research and Technology, Jaipur 302022 (India); Mishra, M. K. [Department of Physics, University of Rajasthan, Jaipur 302004 (India)

    2012-10-15

    Using reductive perturbation method with appropriate boundary conditions, coupled evolution equations for first and second order potentials are derived for ion-acoustic waves in a collisionless, un-magnetized plasma consisting of hot isothermal electrons, cold ions, and massive mobile charged dust grains. The boundary conditions give rise to renormalization term, which enable us to eliminate secular contribution in higher order terms. Determining the non secular solution of these coupled equations, expressions for wave phase velocity and averaged non-linear ion flux associated with ion-acoustic cnoidal wave are obtained. Variation of the wave phase velocity and averaged non-linear ion flux as a function of modulus (k{sup 2}) dependent wave amplitude are numerically examined for different values of dust concentration, charge on dust grains, and mass ratio of dust grains with plasma ions. It is found that for a given amplitude, the presence of positively (negatively) charged dust grains in plasma decreases (increases) the wave phase velocity. This behavior is more pronounced with increase in dust concentrations or increase in charge on dust grains or decrease in mass ratio of dust grains. The averaged non-linear ion flux associated with wave is positive (negative) for negatively (positively) charged dust grains in the plasma and increases (decreases) with modulus (k{sup 2}) dependent wave amplitude. For given amplitude, it increases (decreases) as dust concentration or charge of negatively (positively) charged dust grains increases in the plasma.

  20. The Influence of Trapped Particles on the Parametric Decay Instability of Near-Acoustic Waves

    Science.gov (United States)

    Affolter, M.; Anderegg, F.; Dubin, D. H. E.; Driscoll, C. F.

    2017-10-01

    We present quantitative measurements of a decay instability to lower frequencies of near-acoustic waves. These experiments are conducted on pure ion plasmas confined in a cylindrical Penning-Malmberg trap. The axisymmetric, standing plasma waves have near-acoustic dispersion, discretized by the axial wave number kz =mz(π /Lp) . The nonlinear coupling rates are measured between large amplitude mz = 2 (pump) waves and small amplitude mz = 1 (daughter) waves, which have a small frequency detuning Δω = 2ω1 -ω2 . Classical 3-wave parametric coupling rates are proportional to pump wave amplitude as Γ (δn2 /n0) , with oscillatory energy exchange for Γ Δω / 2 . Experiments on cold plasmas agree quantitatively for oscillatory energy exchange, and agree within a factor-of-two for decay instability rates. However, nascent theory suggest that this latter agreement is merely fortuitous, and that the instability mechanism is trapped particles. Experiments at higher temperatures show that trapped particles reduce the instability threshold below classical 3-wave theory predictions. Supported by NSF Grant PHY-1414570, and DOE Grants DE-SC0002451 and DE-SC0008693. M. Affolter is supported by the DOE FES Postdoctoral Research Program administered by ORISE for the DOE. ORISE is managed by ORAU under DOE Contract Number DE-SC0014664.

  1. 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

  2. Experiments on ion-acoustic shock waves in a dusty plasma

    International Nuclear Information System (INIS)

    Nakamura, Y.

    2002-01-01

    Dust ion-acoustic shock waves have been investigated experimentally in a homogeneous unmagnetized dusty double-plasma device. An initial compressional wave with a ramp shape steepens to form oscillations at the leading part due to dispersion. The oscillation develops to a train of solitons when the plasma contains no dust grain. The wave becomes an oscillatory shock wave when the dust is mixed in the plasma and the density of the dust grains is smaller than a critical value. When the dust density is larger than the critical value, only steepening is observed at the leading part of the wave and a monotonic shock structure is observed. The velocity and width of the shock waves are measured and compared with results of numerical integrations of the modified Korteweg-de Vries-Burgers equation

  3. The power flow angle of acoustic waves in thin piezoelectric plates.

    Science.gov (United States)

    Kuznetsova, Iren E; Zaitsev, Boris D; Teplykh, Andrei A; Joshi, Shrinivas G; Kuznetsova, Anastasia S

    2008-09-01

    The curves of slowness and power flow angle (PFA) of quasi-antisymmetric (A(0)) and quasi-symmetric (S(0)) Lamb waves as well as quasi-shear-horizontal (SH(0)) acoustic waves in thin plates of lithium niobate and potassium niobate of X-,Y-, and Z-cuts for various propagation directions and the influence of electrical shorting of one plate surface on these curves and PFA have been theoretically investigated. It has been found that the group velocity of such waves does not coincide with the phase velocity for the most directions of propagation. It has been also shown that S(0) and SH(0) wave are characterized by record high values of PFA and its change due to electrical shorting of the plate surface in comparison with surface and bulk acoustic waves in the same material. The most interesting results have been verified by experiment. As a whole, the results obtained may be useful for development of various devices for signal processing, for example, electrically controlled acoustic switchers.

  4. Nonlocal analysis of the excitation of the geodesic acoustic mode by drift waves

    DEFF Research Database (Denmark)

    Guzdar, P.N.; Kleva, R.G.; Chakrabarti, N.

    2009-01-01

    The geodesic acoustic modes (GAMs) are typically observed in the edge region of toroidal plasmas. Drift waves have been identified as a possible cause of excitation of GAMs by a resonant three wave parametric process. A nonlocal theory of excitation of these modes in inhomogeneous plasmas typical...... of the edge region of tokamaks is presented in this paper. The continuum GAM modes with coupling to the drift waves can create discrete "global" unstable eigenmodes localized in the edge "pedestal" region of the plasma. Multiple resonantly driven unstable radial eigenmodes can coexist on the edge pedestal....

  5. Instability of nonplanar modulated dust acoustic wave packets in a strongly coupled nonthermal dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    El-Labany, S. K., E-mail: skellabany@hotmail.com; Zedan, N. A., E-mail: nesreenplasma@yahoo.com [Department of Physics, Faculty of Science, Damietta University, New Damietta, P.O. 34517 (Egypt); El-Taibany, W. F., E-mail: eltaibany@hotmail.com, E-mail: eltaibany@du.edu.eg [Department of Physics, Faculty of Science, Damietta University, New Damietta, P.O. 34517 (Egypt); Department of Physics, College of Science for Girls in Abha, King Khalid University, P.O. 960 Abha (Saudi Arabia)

    2015-07-15

    Cylindrical and spherical amplitude modulations of dust acoustic (DA) solitary wave envelopes in a strongly coupled dusty plasma containing nonthermal distributed ions are studied. Employing a reductive perturbation technique, a modified nonlinear Schrödinger equation including the geometrical effect is derived. The influences of nonthermal ions, polarization force, and the geometries on the modulational instability conditions are analyzed and the possible rogue wave structures are discussed in detail. It is found that the spherical DA waves are more structurally stable to perturbations than the cylindrical ones. Possible applications of these theoretical findings are briefly discussed.

  6. Effect of electron beam on the properties of electron-acoustic rogue waves

    Science.gov (United States)

    El-Shewy, E. K.; Elwakil, S. A.; El-Hanbaly, A. M.; Kassem, A. I.

    2015-04-01

    The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, Maxwellian hot electrons, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles and the associated electric field on the carrier wave number, normalized density of hot electron and electron beam, relative cold electron temperature and relative beam temperature are discussed. The results of the present investigation may be applicable in auroral zone plasma.

  7. Dust ion-acoustic solitary waves in a dusty plasma with nonextensive electrons

    Science.gov (United States)

    Bacha, Mustapha; Tribeche, Mouloud; Shukla, Padma Kant

    2012-05-01

    The dust-modified ion-acoustic waves of Shukla and Silin are revisited within the theoretical framework of the Tsallis statistical mechanics. Nonextensivity may originate from correlation or long-range plasma interactions. Interestingly, we find that owing to electron nonextensivity, dust ion-acoustic (DIA) solitary waves may exhibit either compression or rarefaction. Our analysis is then extended to include self-consistent dust charge fluctuation. In this connection, the correct nonextensive electron charging current is rederived. The Korteweg-de Vries equation, as well as the Korteweg-de Vries-Burgers equation, is obtained, making use of the reductive perturbation method. The DIA waves are then analyzed for parameters corresponding to space dusty plasma situations.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  9. Collisionless damping of dust-acoustic waves in a charge varying dusty plasma with nonextensive ions

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-15

    The charge variation induced nonlinear dust-acoustic wave damping in a charge varying dusty plasma with nonextensive ions is considered. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust acoustic wave propagation to be described by a damped Korteweg-de Vries (dK-dV) equation the coefficients of which depend sensitively on the nonextensive parameter q. The damping term, solely due to the dust charge variation, is affected by the ion nonextensivity. For the sake of completeness, the possible effects of nonextensivity and collisionless damping on weakly nonlinear wave packets described by the dK-dV equation are succinctly outlined by deriving a nonlinear Schrödinger-like equation with a complex nonlinear coefficient.

  10. Collisionless damping of dust-acoustic waves in a charge varying dusty plasma with nonextensive ions

    International Nuclear Information System (INIS)

    Amour, Rabia; Tribeche, Mouloud

    2014-01-01

    The charge variation induced nonlinear dust-acoustic wave damping in a charge varying dusty plasma with nonextensive ions is considered. It is shown that the collisionless damping due to dust charge fluctuation causes the nonlinear dust acoustic wave propagation to be described by a damped Korteweg-de Vries (dK-dV) equation the coefficients of which depend sensitively on the nonextensive parameter q. The damping term, solely due to the dust charge variation, is affected by the ion nonextensivity. For the sake of completeness, the possible effects of nonextensivity and collisionless damping on weakly nonlinear wave packets described by the dK-dV equation are succinctly outlined by deriving a nonlinear Schrödinger-like equation with a complex nonlinear coefficient

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

    Energy Technology Data Exchange (ETDEWEB)

    Ichihara, Mie; Lyons, John; Oikawa, Jun; Takeo, Minoru [Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Instituto Geofisico, Escuela Politecnica Nacional, Ladron de Guevara E11-253, Aptdo 2759, Quito (Ecuador); Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan)

    2012-09-04

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

  12. 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

  13. Resonant transmission and mode modulation of acoustic waves in H-shaped metallic gratings

    International Nuclear Information System (INIS)

    Deng, Yu-Qiang; Fan, Ren-Hao; Zhang, Kun; Peng, Ru-Wen; Qi, Dong-Xiang

    2015-01-01

    In this work, we demonstrate that resonant full transmission of acoustic waves exists in subwavelength H-shaped metallic gratings, and transmission peaks can be efficiently tuned by adjusting the grating geometry. We investigate this phenomenon through both numerical simulations and theoretical calculations based on rigorous-coupled wave analysis. The transmission peaks are originated from Fabry-Perot resonances together with the couplings between the diffractive wave on the surface and the multiple guided modes in the slits. Moreover, the transmission modes can be efficiently tuned by adjusting the cavity geometry, without changing the grating thickness. The mechanism is analyzed based on an equivalent circuit model and verified by both the theoretical calculations and the numerical simulations. This research has potential application in acoustic-device miniaturization over a wide range of wavelengths

  14. Finite Element Analysis of the Propagation of Acoustic Waves Along Waveguides Immersed in Water

    Science.gov (United States)

    Hladky-Hennion, A.-C.; Langlet, P.; de Billy, M.

    1997-03-01

    The finite element approach has previously been used, with the help of the ATILA code, to model the propagation of acoustic waves in waveguides [A.-C. Hladky-Hennion, Journal of Sound and Vibration, 194,119-136 (1996)]. In this paper an extension of the technique to the analysis of the propagation of acoustic waves in immersed waveguides is presented. In the proposed approach, the problem is reduced to a bidimensional problem, in which only the cross-section of the guide and the surrounding fluid domain are meshed by using finite elements. Then, wedges the top angles of which vary, are studied and the finite element results of the wedge wave speed are compared with experimental results. Finally, the conclusion indicates a way to extend this approach to waveguides of any cross-section.

  15. Miniature acoustic wave lysis system and uses thereof

    Science.gov (United States)

    Branch, Darren W.; Vreeland, Erika Cooley; Smith, Gennifer Tanabe

    2016-12-06

    The present invention relates to an acoustic lysis system including a disposable cartridge that can be reversibly coupled to a platform having a small, high-frequency piezoelectric transducer array. In particular, the system releases viable DNA, RNA, and proteins from human or bacterial cells, without chemicals or additional processing, to enable high-speed sample preparation for clinical point-of-care medical diagnostics and use with nano/microfluidic cartridges. Also described herein are methods of making and using the system of the invention.

  16. 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.

  17. 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)...

  18. 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%).

  19. 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.

  20. 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.