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Sample records for acoustic resonance signatures

  1. Fissile and Non-Fissile Material Detection using Nuclear Acoustic Resonance Signatures

    Herberg, J; Maxwell, R; Tittmann, B R; Lenahan, P M; Yerkes, S; Jayaraman, S

    2005-10-04

    This report reviews progress made on NA22 project LL251DP to develop a novel technique, Nuclear Acoustic Resonance (NAR), for remote, non-destructive, nonradiation-based detection of materials of interest to Nonproliferation Programs, including {sup 235}U and {sup 239}Pu. We have met all milestones and deliverables for FY05, as shown in Table 1. In short, we have developed a magnetic shield chamber and magnetic field, develop a digital lock-in amplifier computer to integrate both the ultrasound radiation with the detector, developed strain measurements, and begin to perform initial measurements to obtain a NAR signal from aluminum at room temperature and near the earth's magnetic field. The results obtained in FY05 further support the feasibility of successful demonstration of an NAR experiment for remote, non-destructive, non-radiation-based detection of materials of interest to Nonproliferation Programs.

  2. Fissile and Non-Fissile Material Detection using Nuclear Acoustic Resonance Signatures: Final Report

    Herberg, J; Maxwell, R; Tittmann, B R; Lenahan, P M; Yerkes, S; Jayaraman, S B

    2006-11-02

    This is final report on NA-22 project LL251DP, where the goal was to develop a novel technique, Nuclear Acoustic Resonance (NAR), for remote, non-destructive, nonradiation-based detection of materials of interest to Nonproliferation Programs, including {sup 235}U and {sup 239}Pu. In short, we have developed a magnetic shield chamber and magnetic field, develop a digital lock-in amplifier computer to integrate both the ultrasound radiation with the detector, developed strain measurements, and begun to perform initial measurements to obtain a NAR signal from aluminum at room temperature and near the earth's magnetic field. Since our funding was cut in FY06, I will discuss where this project can go in the future with this technology.

  3. Acoustic Signature Monitoring and Management of Naval Platforms

    Basten, T.G.H.; Jong, C.A.F. de; Graafland, F.; Hof, J. van 't

    2015-01-01

    Acoustic signatures make naval platforms susceptible to detection by threat sensors. The variable operational conditions and lifespan of a platform cause variations in the acoustic signature. To deal with these variations, a real time signature monitoring capability is being developed, with advisory

  4. Acoustic metasurface with hybrid resonances.

    Ma, Guancong; Yang, Min; Xiao, Songwen; Yang, Zhiyu; Sheng, Ping

    2014-09-01

    An impedance-matched surface has the property that an incident wave generates no reflection. Here we demonstrate that by using a simple construction, an acoustically reflecting surface can acquire hybrid resonances and becomes impedance-matched to airborne sound at tunable frequencies, such that no reflection is generated. Each resonant cell of the metasurface is deep-subwavelength in all its spatial dimensions, with its thickness less than the peak absorption wavelength by two orders of magnitude. As there can be no transmission, the impedance-matched acoustic wave is hence either completely absorbed at one or multiple frequencies, or converted into other form(s) of energy, such as an electrical current. A high acoustic-electrical energy conversion efficiency of 23% is achieved. PMID:24880731

  5. Acoustic Fano resonators

    Amin, Muhammad

    2014-07-01

    The resonances with asymmetric Fano line-shapes were originally discovered in the context of quantum mechanics (U. Fano, Phys. Rev., 124, 1866-1878, 1961). Quantum Fano resonances were generated from destructive interference of a discrete state with a continuum one. During the last decade this concept has been applied in plasmonics where the interference between a narrowband polariton and a broader one has been used to generate electromagnetically induced transparency (EIT) (M. Rahmani, et al., Laser Photon. Rev., 7, 329-349, 2013).

  6. Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens

    Cheng, Ying; Liu, XiaoJun, E-mail: liuxiaojun@nju.edu.cn [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Zhou, Chen; Wei, Qi; Wu, DaJian [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China)

    2013-11-25

    Early research into acoustic metamaterials has shown the possibility of achieving subwavelength near-field acoustic imaging. However, a major restriction of acoustic metamaterials is that the imaging objects must be placed in close vicinity of the devices. Here, we present an approach for acoustic imaging of subsurface objects far below the diffraction limit. An acoustic metalens made of holey-structured metamaterials is used to magnify evanescent waves, which can rebuild an image at the central plane. Without changing the physical structure of the metalens, our proposed approach can image objects located at certain distances from the input surface, which provides subsurface signatures of the objects with subwavelength spatial resolution.

  7. Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens

    Early research into acoustic metamaterials has shown the possibility of achieving subwavelength near-field acoustic imaging. However, a major restriction of acoustic metamaterials is that the imaging objects must be placed in close vicinity of the devices. Here, we present an approach for acoustic imaging of subsurface objects far below the diffraction limit. An acoustic metalens made of holey-structured metamaterials is used to magnify evanescent waves, which can rebuild an image at the central plane. Without changing the physical structure of the metalens, our proposed approach can image objects located at certain distances from the input surface, which provides subsurface signatures of the objects with subwavelength spatial resolution

  8. Modeling ground vehicle acoustic signatures for analysis and synthesis

    Security and weapon systems use acoustic sensor signals to classify and identify moving ground vehicles. Developing robust signal processing algorithms for this is expensive, particularly in presence of acoustic clutter or countermeasures. This paper proposes a parametric ground vehicle acoustic signature model to aid the system designer in understanding which signature features are important, developing corresponding feature extraction algorithms and generating low-cost, high-fidelity synthetic signatures for testing. The authors have proposed computer-generated acoustic signatures of armored, tracked ground vehicles to deceive acoustic-sensored smart munitions. They have developed quantitative measures of how accurately a synthetic acoustic signature matches those produced by actual vehicles. This paper describes parameters of the model used to generate these synthetic signatures and suggests methods for extracting these parameters from signatures of valid vehicle encounters. The model incorporates wide-bandwidth and narrow- bandwidth components that are modulated in a pseudo-random fashion to mimic the time dynamics of valid vehicle signatures. Narrow- bandwidth feature extraction techniques estimate frequency, amplitude and phase information contained in a single set of narrow frequency- band harmonics. Wide-bandwidth feature extraction techniques estimate parameters of a correlated-noise-floor model. Finally, the authors propose a method of modeling the time dynamics of the harmonic amplitudes as a means adding necessary time-varying features to the narrow-bandwidth signal components. The authors present results of applying this modeling technique to acoustic signatures recorded during encounters with one armored, tracked vehicle. Similar modeling techniques can be applied to security systems

  9. Acoustic resonance spectroscopy intrinsic seals

    We have begun to quantify the ability of acoustic resonance spectroscopy (ARS) to detect the removal and replacement of the lid of a simulated special nuclear materials drum. Conceptually, the acoustic spectrum of a container establishcs a baseline fingerprint, which we refer to as an intrinsic seal, for the container. Simply removing and replacing the lid changes some of the resonant frequencies because it is impossible to exactly duplicate all of the stress patterns between the lid and container. Preliminary qualitative results suggested that the ARS intrinsic seal could discriminate between cases where a lid has or has not been removed. The present work is directed at quantifying the utility of the ARS intrinsic seal technique, including the technique's sensitivity to ''nuisance'' effects, such as temperature swings, movement of the container, and placement of the transducers. These early quantitative tests support the potential of the ARS intrinsic seal application, but also reveal a possible sensitivity to nuisance effects that could limit environments or conditions under which the technique is effective

  10. Acoustic resonance for nonmetallic mine detection

    Kercel, S.W.

    1998-04-01

    The feasibility of acoustic resonance for detection of plastic mines was investigated by researchers at the Oak Ridge National Laboratory`s Instrumentation and Controls Division under an internally funded program. The data reported in this paper suggest that acoustic resonance is not a practical method for mine detection. Representative small plastic anti-personnel mines were tested, and were found to not exhibit detectable acoustic resonances. Also, non-metal objects known to have strong acoustic resonances were tested with a variety of excitation techniques, and no practical non-contact method of exciting a consistently detectable resonance in a buried object was discovered. Some of the experimental data developed in this work may be useful to other researchers seeking a method to detect buried plastic mines. A number of excitation methods and their pitfalls are discussed. Excitation methods that were investigated include swept acoustic, chopped acoustic, wavelet acoustic, and mechanical shaking. Under very contrived conditions, a weak response that could be attributed to acoustic resonance was observed, but it does not appear to be practical as a mine detection feature. Transfer properties of soil were investigated. Impulse responses of several representative plastic mines were investigated. Acoustic leakage coupling, and its implications as a disruptive mechanism were investigated.

  11. Acoustic transparency and slow sound using detuned acoustic resonators

    Santillan, Arturo Orozco; Bozhevolnyi, Sergey I.

    2011-01-01

    We demonstrate that the phenomenon of acoustic transparency and slowsound propagation can be realized with detuned acoustic resonators (DAR), mimicking thereby the effect of electromagnetically induced transparency (EIT) in atomic physics. Sound propagation in a pipe with a series of side...

  12. Acoustic Resonance Reaction Control Thruster (ARCTIC) Project

    National Aeronautics and Space Administration — ORBITEC proposes to develop and demonstrate the innovative Acoustic Resonance Reaction Control Thruster (ARCTIC) to provide rapid and reliable in-space impulse...

  13. Humanitarian mine detection by acoustic resonance

    Kercel, S.W.

    1998-03-01

    The JASON Committee at MITRE Corp. was tasked by DARPA to inquire into suitable technologies for humanitarian mine detection. Acoustic resonance was one of the very few technologies that the JASONs determined might be promising for the task, but was as yet unexplored at the time that they conducted their inquiry. The objective of this Seed Money investigation into acoustic resonance was to determine if it would be feasible to use acoustic resonance to provide an improvement to present methods for humanitarian mine detection. As detailed in this report, acoustic resonance methods do not appear to be feasible for this task. Although acoustic resonant responses are relatively easy to detect when they exist, they are very difficult to excite by the non-contact means that must be used for buried objects. Despite many different attempts, this research did not discover any practical means of using sound to excite resonant responses in objects known to have strong resonances. The shaker table experiments did see an effect that might be attributable to the resonance of the object under test, but the effect was weak, and exploited the a priori knowledge of the resonant frequency of the object under test to distinguish it from the background. If experiments that used objects known to have strong acoustic resonances produced such marginal results, this does not seem to be a practical method to detect objects with weak resonances or non-existent resonances. The results of this work contribute to the ORNL countermine initiative. ORNL is exploring several unconventional mine detection technologies, and is proposed to explore others. Since this research has discovered some major pitfalls in non-metallic mine detection, this experience will add realism to other strategies proposed for mine detection technologies. The experiment provided hands-on experience with inert plastic mines under field conditions, and gives ORNL additional insight into the problems of developing practical

  14. Multifrequency acoustic resonators with variable nonuniformity

    Alkov, Steven L.

    1991-01-01

    Approved for public release; distribution is unlimited A new type of acoustic resonator utilizes alterations of the nonuniformity to achieve different resonance frequencies. Each resonator is designed to yield frequencies that correspond to musical notes. The apparatus are remarkably simple, employing piecewise uniform cross sectional areas that can easily and quickly be changed. The resonators are thus useful as educational demonstrations. The phenomenon can be understood physically a...

  15. Resonant acoustic radiation force optical coherence elastography

    Qi, Wenjuan; Li, Rui; Ma, Teng; Li, Jiawen; Kirk Shung, K.; Zhou, Qifa; Chen, Zhongping

    2013-01-01

    We report on a resonant acoustic radiation force optical coherence elastography (ARF-OCE) technique that uses mechanical resonant frequency to characterize and identify tissues of different types. The linear dependency of the resonant frequency on the square root of Young's modulus was validated on silicone phantoms. Both the frequency response spectrum and the 3D imaging results from the agar phantoms with hard inclusions confirmed the feasibility of deploying the resonant frequency as a mec...

  16. Acoustic microscopy applied to resonator characterization

    This paper describes the characteristics of acoustic resonators and the techniques used to characterize the standing wave patterns. It is shown that these patterns can be observed by the acoustic microscope in a transmission mode. Results are presented for circular and rectangular transducers showing the effects of supporting mount leads and defects on the vibration characteristics. The development of new more direct techniques for observing the acoustic resonances of piezoelectric transducers is of considerable interest since some of the other methods previously applied are indirect in nature and suffer from different limitations

  17. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

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

    2016-05-01

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

  18. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    N. I. Polzikova

    2016-05-01

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

  19. Spin-3/2 Pentaquark Resonance Signature

    We search for the standard lattice resonance signature of attraction between the resonance constituents which leads to a bound state at quark masses near the physical regime. We study a variety of spin-1/2 interpolators and for the first time, interpolators providing access to spin-3/2 pentaquark states. In looking for evidence of binding, a precise determination of the mass splitting between the pentaquark state and its lowest-lying decay channel is performed by constructing the effective mass splitting from the various two-point correlation functions. While the binding of the pentaquark state is not a requirement, the observation of such binding would provide compelling evidence for the existence of the theta+ pentaquark resonance. Evidence of binding is observed in the isoscalar spin-3/2 positive parity channel, making it an interesting state for further research

  20. Acoustic Resonator Optimisation for Airborne Particle Manipulation

    Devendran, Citsabehsan; Billson, Duncan R.; Hutchins, David A.; Alan, Tuncay; Neild, Adrian

    Advances in micro-electromechanical systems (MEMS) technology and biomedical research necessitate micro-machined manipulators to capture, handle and position delicate micron-sized particles. To this end, a parallel plate acoustic resonator system has been investigated for the purposes of manipulation and entrapment of micron sized particles in air. Numerical and finite element modelling was performed to optimise the design of the layered acoustic resonator. To obtain an optimised resonator design, careful considerations of the effect of thickness and material properties are required. Furthermore, the effect of acoustic attenuation which is dependent on frequency is also considered within this study, leading to an optimum operational frequency range. Finally, experimental results demonstrated good particle levitation and capture of various particle properties and sizes ranging to as small as 14.8 μm.

  1. Multilayer Integrated Film Bulk Acoustic Resonators

    Zhang, Yafei

    2013-01-01

    Multilayer Integrated Film Bulk Acoustic Resonators mainly introduces the theory, design, fabrication technology and application of a recently developed new type of device, multilayer integrated film bulk acoustic resonators, at the micro and nano scale involving microelectronic devices, integrated circuits, optical devices, sensors and actuators, acoustic resonators, micro-nano manufacturing, multilayer integration, device theory and design principles, etc. These devices can work at very high frequencies by using the newly developed theory, design, and fabrication technology of nano and micro devices. Readers in fields of IC, electronic devices, sensors, materials, and films etc. will benefit from this book by learning the detailed fundamentals and potential applications of these advanced devices. Prof. Yafei Zhang is the director of the Ministry of Education’s Key Laboratory for Thin Films and Microfabrication Technology, PRC; Dr. Da Chen was a PhD student in Prof. Yafei Zhang’s research group.

  2. Magnetic resonance imaging of acoustic neuroma

    Kashihara, Kengo; Murata, Hideaki; Ito, Haruhide; Onishi, Hiroaki; Kadoya, Masumi; Suzuki, Masayuki.

    1989-03-01

    Thirteen patients with acoustic neuroma were studied on a 1.5T superconductive magnetic resonance (MR) imager. Acoustic neuromas appeared as lower signal intensity than the surrounding brain stem on T1 weighted image (W.I.), and as higher signal intensity on T2 W.I.. Axial and coronal sections of T1 W.I. were very useful in observing the tumor in the auditory canal and in investigating the anatomical relations of the tumor and the surrounding structures. MR imaging is very excellent examination to make early diagnosis of the acoustic neuroma and preoperative anatomical evaluation.

  3. Prototype acoustic resonance spectroscopy monitor

    This report reports on work performed for the International Atomic Energy Agency (IAEA) through the Program Office for Technical Assistance (POTAS). In this work, we investigate possible applications of nondestructive acoustics measurements to facilitate IAEA safeguards at bulk processing facilities. Two different acoustic techniques for verifying the internal structure of a processing tank were investigated. During this effort we also examined two acoustic techniques for assessing the fill level within a processing tank. The fill-level measurements could be made highly portable and have an added safeguards advantage that they can also detect stratification of fill material. This later application may be particularly useful in confirming the absence of stratification in plutonium processing tanks before accountability samples are withdrawn

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

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

    2013-10-01

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

  5. Wave Phenomena in an Acoustic Resonant Chamber

    Smith, Mary E.; And Others

    1974-01-01

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

  6. Estimation of acoustic resonances for room transfer function equalization

    Gil-Cacho, Pepe; van Waterschoot, Toon; Moonen, Marc; Jensen, Søren Holdt

    2010-01-01

    Strong acoustic resonances create long room impulse responses (RIRs) which may harm the speech transmission in an acoustic space and hence reduce speech intelligibility. Equalization is performed by cancelling the main acoustic resonances common to multiple room transfer functions (RTFs), i...

  7. Conversion acoustic resonances in orthorhombic crystals

    Lyubimov, V. N.; Bessonov, D. A.; Alshits, V. I.

    2016-05-01

    A classification of acoustic-beam reflection resonances in orthorhombic crystals under conditions where a proximity to conversion is implemented in the vicinity of total internal reflection is proposed. In this case, the energy from the incident pump beam falls almost entirely into a narrow intense reflected beam propagating at a small angle with respect to the surface. The crystal boundary is parallel to one of the elastic symmetry planes, and the excited beam propagates near one of axes 2 in this plane. Depending on the relations between the elastic moduli and the chosen propagation geometry, 18 types of resonances may occur, but no more than three in each crystal. The developed theory combines an approximate analytical description and accurate computer analysis. The relations between the elastic moduli providing minimum energy loss over the parasite reflected wave are determined. Some crystals with resonant excitation very close to conversion are revealed.

  8. Parametric resonance in acoustically levitated water drops

    Shen, C.L.; Xie, W.J. [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China); Wei, B., E-mail: bbwei@nwpu.edu.c [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2010-05-10

    Liquid drops can be suspended in air with acoustic levitation method. When the sound pressure is periodically modulated, the levitated drop is usually forced into an axisymmetric oscillation. However, a transition from axisymmetric oscillation into sectorial oscillation occurs when the modulation frequency approaches some specific values. The frequency of the sectorial oscillation is almost exactly half of the modulation frequency. It is demonstrated that this transition is induced by the parametric resonance of levitated drop. The natural frequency of sectorial oscillation is found to decrease with the increase of drop distortion extent.

  9. Algorithm for classifying multiple targets using acoustic signatures

    Damarla, Thyagaraju; Pham, Tien; Lake, Douglas

    2004-08-01

    In this paper we discuss an algorithm for classification and identification of multiple targets using acoustic signatures. We use a Multi-Variate Gaussian (MVG) classifier for classifying individual targets based on the relative amplitudes of the extracted harmonic set of frequencies. The classifier is trained on high signal-to-noise ratio data for individual targets. In order to classify and further identify each target in a multi-target environment (e.g., a convoy), we first perform bearing tracking and data association. Once the bearings of the targets present are established, we next beamform in the direction of each individual target to spatially isolate it from the other targets (or interferers). Then, we further process and extract a harmonic feature set from each beamformed output. Finally, we apply the MVG classifier on each harmonic feature set for vehicle classification and identification. We present classification/identification results for convoys of three to five ground vehicles.

  10. Feature extraction from time domain acoustic signatures of weapons systems fire

    Yang, Christine; Goldman, Geoffrey H.

    2014-06-01

    The U.S. Army is interested in developing algorithms to classify weapons systems fire based on their acoustic signatures. To support this effort, an algorithm was developed to extract features from acoustic signatures of weapons systems fire and applied to over 1300 signatures. The algorithm filtered the data using standard techniques then estimated the amplitude and time of the first five peaks and troughs and the location of the zero crossing in the waveform. The results were stored in Excel spreadsheets. The results are being used to develop and test acoustic classifier algorithms.

  11. Tuneable film bulk acoustic wave resonators

    Gevorgian, Spartak Sh; Vorobiev, Andrei K

    2013-01-01

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

  12. Acoustic metamaterials with piezoelectric resonant structures

    A resonant structure of a hard-core coated by piezoelectric composite materials is proposed as an acoustic metamaterial (AM), in which a negative effective mass density and elastic modulus are simultaneously achieved. The double negativity, appearing within a certain range of the filling ratio, is numerically demonstrated by the switch of the electrical boundary from open to closed. The bandwidth of the negative effective elastic modulus is sensitive to the piezoelectric constant e33. The multi-unit AM offers the advantages of broadening the double-negativity domain and of reducing the primary frequency, while the cut-up frequency remains the same as that of the single-unit cell AM. (paper)

  13. Acoustic scattering from a submerged cylindrical shell coated with locally resonant acoustic metamaterials

    Using the multilayered cylinder model, we study acoustic scattering from a submerged cylindrical shell coated with locally resonant acoustic metamaterials, which exhibit locally negative effective mass densities. A spring model is introduced to replace the traditional transfer matrix, which may be singular in the negative mass region. The backscattering form function and the scattering cross section are calculated to discuss the acoustic properties of the coated submerged cylindrical shell. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  14. Magnetic resonance imaging of acoustic neurinomas

    A restrospective review was made on magnetic resonance imaging (MRI) scans, preoperative neuro-otological findings, and surgical results for hearing preservation in 20 consecutive patients with histologically verified acoustic neurinomas. The maximum diameter of the tumor, both in the cerebellopontine angle (CPA) and internal auditory canal (IAC), were measured by MRI scans to classify tumor size. The signal intensity of acoustic neurinoma was equal to or lower than that of the adjacent pons on T1-weighted images and higher on T2-weighted images. After the administration of Gd-DTPA, tumors were markedly enhanced, which appeared homogeneous for small tumors and heterogeneous for large ones. There was no relationship between the degree of preoperative hearing loss and tumor size in either the CPA or the IAC. The larger the tumor in the CPA, however, the more often did the response to a caloric test disappear or decrease greatly. In contrast, there was no apparent correlation between the caloric response and tumor size in the IAC. Twelve patients (60%) had serviceable hearing (pure tone average loss 50%) preoperatively: the average tumor size in this group was similar to that in patients with poor or no hearing. These 12 patients were considered to be candidates for hearing preservation at surgery: 5 (41.7%) retained serviceable hearing postoperatively. A mean tumor size in the CPA was 11.8 mm for patients with postoperative serviceable hearing and 21.3 mm for those without it. Moreover, hearing was preserved postoperatively in all 4 patients with tumor less than 5 mm in the IAC. Thus, hearing preservation after surgery seemed to be closely related to tumor size. This study confirmed the value of MRI, providing information for the evaluation of hearing-preservation surgery. (N.K.)

  15. Active Cancellation of Acoustical Resonances with an FPGA FIR Filter

    Ryou, Albert

    2016-01-01

    We present a novel approach to enhancing the bandwidth of a feedback-controlled mechanical system by digitally canceling acoustical resonances (poles) and anti-resonances (zeros) in the open-loop response via an FPGA FIR filter. By performing a real-time convolution of the feedback error signal with an inverse filter, we can suppress arbitrarily many poles and zeros below 100 kHz, each with a linewidth down to 10 Hz. We demonstrate the efficacy of this technique by canceling the ten largest mechanical resonances and anti-resonances of a high-finesse optical resonator, thereby enhancing the unity gain frequency by more than an order of magnitude. This approach is applicable to a broad array of stabilization problems including optical resonators, external cavity diode lasers, and scanning tunneling microscopes, and points the way to applying modern optimal control techniques to intricate linear acoustical systems.es to intricate linear acoustical systems.

  16. Flow Induced Acoustic Resonance in In-line Tube Banks

    Hiromitsu Hamakawa; Tohru Fukano; Eiichi Nishida; Yoshikazu Satou

    2006-01-01

    In the present paper the attention is focused on the relation between vortex shedding phenomena and acoustic resonance which occurred in the two-dimensional model of boiler. There were tube banks with in-line arrangement for small tube pitch ratio. We measured the sound pressure level, the phase delay of acoustic pressures, the spectrum of velocity fluctuation and the gap velocity. As a result, we found two peak frequencies of sound pressure level with different Strouhal numbers St, mainly about 0.26 and 0.52. The noise of St=0.26 was the resonance of transverse mode and St=0.52 was longitudinal mode. The vortex shedding of St=0.15 was generated inside the tube banks without acoustic resonance. As gap velocity increased, we observed that the peak level of spectrum was weak and broad-banded. The onset velocity of the acoustic resonance of longitudinal mode was lower than that of transverse mode.

  17. Acoustic Resonance Frequency Elimination Device for Safety Relief Valves

    Industry experience has shown that Safety Relief Valves (SRVs) and Steam Dryers installed in Boiling Water Reactors (BWRs) experience vibration induced degradation and failures caused by acoustic resonance vibration of the main steam lines, resulting in decreased reliability and potential safety issues. The resonance is caused by vortex shedding from the standpipe inlet and acoustic standing waves in the standpipe, occurring when the two frequencies match. (Author)

  18. Experimental realization of extraordinary acoustic transmission using Helmholtz resonators

    The phenomenon of extraordinary acoustic transmission through a solid barrier with an embedded Helmholtz resonator (HR) is demonstrated. The Helmholtz resonator consists of an embedded cavity and two necks that protrude, one on each side of the barrier. Extraordinary transmission occurs for a narrow spectral range encompassing the resonant frequency of the Helmholtz resonator. We show that an amplitude transmission of 97.5% is achieved through a resonator whose neck creates an open area of 6.25% of the total barrier area. In addition to the enhanced transmission, we show that there is a smooth, continuous phase transition in the transmitted sound as a function of frequency. The frequency dependent phase transition is used to experimentally realize slow wave propagation for a narrow-band Gaussian wave packet centered at the maximum transmission frequency. The use of parallel pairs of Helmholtz resonators tuned to different resonant frequencies is experimentally explored as a means of increasing the transmission bandwidth. These experiments show that because of the phase transition, there is always a frequency between the two Helmholtz resonant frequencies at which destructive interference occurs whether the resonances are close or far apart. Finally, we explain how the phase transition associated with Helmholtz-resonator-mediated extraordinary acoustic transmission can be exploited to produce diffractive acoustic components including sub-wavelength thickness acoustic lenses

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

    Amoudache, Samira; Moiseyenko, Rayisa; Pennec, Yan; Rouhani, Bahram Djafari; Khater, Antoine; Lucklum, Ralf; Tigrine, Rachid

    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...... 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....

  20. On the acoustic signature of tandem airfoils: The sound of an elastic airfoil in the wake of a vortex generator

    Manela, A.

    2016-07-01

    The acoustic signature of an acoustically compact tandem airfoil setup in uniform high-Reynolds number flow is investigated. The upstream airfoil is considered rigid and is actuated at its leading edge with small-amplitude harmonic pitching motion. The downstream airfoil is taken passive and elastic, with its motion forced by the vortex-street excitation of the upstream airfoil. The non-linear near-field description is obtained via potential thin-airfoil theory. It is then applied as a source term into the Powell-Howe acoustic analogy to yield the far-field dipole radiation of the system. To assess the effect of downstream-airfoil elasticity, results are compared with counterpart calculations for a non-elastic setup, where the downstream airfoil is rigid and stationary. Depending on the separation distance between airfoils, airfoil-motion and airfoil-wake dynamics shift between in-phase (synchronized) and counter-phase behaviors. Consequently, downstream airfoil elasticity may act to amplify or suppress sound through the direct contribution of elastic-airfoil motion to the total signal. Resonance-type motion of the elastic airfoil is found when the upstream airfoil is actuated at the least stable eigenfrequency of the downstream structure. This, again, results in system sound amplification or suppression, depending on the separation distance between airfoils. With increasing actuation frequency, the acoustic signal becomes dominated by the direct contribution of the upstream airfoil motion, whereas the relative contribution of the elastic airfoil to the total signature turns negligible.

  1. The acoustic signatures of cavitation erosion on grade DH36 steel

    Armakolas, I.; Carlton, J.; Vidakovic, M.; Sun, T.; Grattan, K. T. V.

    2015-12-01

    Cavitation can cause considerable erosion to adjacent materials. Erosion is accompanied by acoustic emissions, related to crack formation and propagation inside the material. In this study a piezoelectric acoustic sensor mounted on the back of a grade DH36 steel plate is used to identify the acoustic signatures of cavitation. Cavitation is induced near the plate by means of an ultrasonic transducer (sonotrode). Various ‘non-erosive’ and erosive test rig configurations are examined and an acoustic threshold value for the onset of cavitation erosion is identified and presented. The use of a fibre Bragg grating (FBG)-based acoustic sensor developed at City University London for acoustic monitoring purposes is also examined. Acoustic signals from both sensors are analysed, by means of a fast Fourier transform, showing a very good agreement in terms of captured frequencies.

  2. Acoustic scattering from a submerged cylindrical shell coated with locally resonant acoustic metamaterials

    Li Li; Wen Ji-Hong; Cai Li; Zhao Hong-Gang; Wen Xi-Sen

    2013-01-01

    Using the multilayered cylinder model,we study acoustic scattering from a submerged cylindrical shell coated with locally resonant acoustic metamaterials,which exhibit locally negative effective mass densities.A spring model is introduced to replace the traditional transfer matrix,which may be singular in the negative mass region.The backscattering form function and the scattering cross section are calculated to discuss the acoustic properties of the coated submerged cylindrical shell.

  3. Acoustically induced transparency using Fano resonant periodic arrays

    Amin, M.; Elayouch, A.; Farhat, M.; Addouche, M.; Khelif, A.; Baǧcı, H.

    2015-10-01

    A three-dimensional acoustic device, which supports Fano resonance and induced transparency in its response to an incident sound wave, is designed and fabricated. These effects are generated from the destructive interference of closely coupled one broad- and one narrow-band acoustic modes. The proposed design ensures excitation and interference of two spectrally close modes by locating a small pipe inside a wider and longer one. Indeed, numerical simulations and experiments demonstrate that this simple-to-fabricate structure can be used to generate Fano resonance as well as acoustically induced transparency with promising applications in sensing, cloaking, and imaging.

  4. Acoustically induced transparency using Fano resonant periodic arrays

    Amin, M.

    2015-10-22

    A three-dimensional acoustic device, which supports Fano resonance and induced transparency in its response to an incident sound wave, is designed and fabricated. These effects are generated from the destructive interference of closely coupled one broad- and one narrow-band acoustic modes. The proposed design ensures excitation and interference of two spectrally close modes by locating a small pipe inside a wider and longer one. Indeed, numerical simulations and experiments demonstrate that this simple-to-fabricate structure can be used to generate Fano resonance as well as acoustically induced transparency with promising applications in sensing, cloaking, and imaging.

  5. Numerical study on the valve acoustic resonance behaviors

    Background: In recent years some reactors have experienced significant steam dryer cracking. Studies indicate that the fatigue is due to flow-induced acoustic vibration. Purpose: In this study, sound source behaviors of a single valve on the main steam line are investigated. Methods: Mode and CFD analysis were carried to investigate the acoustic mode and resonance behaviors. Results: The following results can be concluded from this study: various categories of acoustic modes exist in the structure; geometries directly influence acoustic mode; peak excitation occurs around St of some specifically range. Conclusions: The results match theory and experimental studies well, and provide reference for the related researches. (authors)

  6. Acoustic control in enclosures using optimally designed Helmholtz resonators

    Driesch, Patricia Lynne

    A virtual design methodology is developed to minimize the noise in enclosures with optimally designed, passive, acoustic absorbers (Helmholtz resonators). A series expansion of eigen functions is used to represent the acoustic absorbers as external volume velocities, eliminating the need for a solution of large matrix eigen value problems. A determination of this type (efficient model/reevaluation approach) significantly increases the design possibilities when optimization techniques are implemented. As a benchmarking exercise, this novel methodology was experimentally validated for a narrowband acoustic assessment of two optimally designed Helmholtz resonators coupled to a 2D enclosure. The resonators were tuned to the two lowest resonance frequencies of a 30.5 by 40.6 by 2.5 cm (12 x 16 x 1 inch) cavity with the resonator volume occupying only 2% of the enclosure volume. A maximum potential energy reduction of 12.4 dB was obtained at the second resonance of the cavity. As a full-scale demonstration of the efficacy of the proposed design method, the acoustic response from 90--190 Hz of a John Deere 7000 Ten series tractor cabin was investigated. The lowest cabin mode, referred to as a "boom" mode, proposes a significant challenge to a noise control engineer since its anti-node is located near the head of the operator and often generates unacceptable sound pressure levels. Exploiting the low frequency capability of Helmholtz resonators, lumped parameter models of these resonators were coupled to the enclosure via an experimentally determined acoustic model of the tractor cabin. The virtual design methodology uses gradient optimization techniques as a post processor for the modeling and analysis of the unmodified acoustic interior to determine optimal resonator characteristics. Using two optimally designed Helmholtz resonators; potential energy was experimentally reduced by 3.4 and 10.3 dB at 117 and 167 Hz, respectively.

  7. Active electroacoustic resonators with negative acoustic properties

    Lissek, Hervé; Boulandet, Romain

    2012-01-01

    Acoustic metamaterials constitute a new class of acoustic structures, composed of periodic arrangements of engineered unit-cells, that exhibit macroscopic acoustic properties not readily available in nature. These properties can either be a negative mass density or a negative bulk modulus. However, these artificial behaviours derive from the engineered arrangement of the unit-cells, which do not present individual ''meta-properties'', rather than from their intrinsic nature. It is although po...

  8. Surface resonant states and superlensing in acoustic metamaterials

    Ambati, Muralidhar; Fang, Nicholas; Sun, Cheng; Zhang, Xiang

    2007-05-01

    We report that the negative material responses of acoustic metamaterials can lead to a plethora of surface resonant states. We determine that negative effective-mass density is the necessary condition for the existence of surface states on acoustic metamaterials. We offer the microscopic picture of these unique surface states; in addition, we find that these surface excitations enhance the transmission of evanescent pressure fields across the metamaterial. The evanescent pressure fields scattered from an object can be resonantly coupled and enhanced at the surface of the acoustic metamaterial, resulting in an image with resolution below the diffraction limit. This concept of acoustic superlens opens exciting opportunities to design acoustic metamaterials for ultrasonic imaging.

  9. Acoustic metamaterials: From local resonances to broad horizons

    Ma, Guancong; Sheng, Ping

    2016-01-01

    Within a time span of 15 years, acoustic metamaterials have emerged from academic curiosity to become an active field driven by scientific discoveries and diverse application potentials. This review traces the development of acoustic metamaterials from the initial findings of mass density and bulk modulus frequency dispersions in locally resonant structures to the diverse functionalities afforded by the perspective of negative constitutive parameter values, and their implications for acoustic wave behaviors. We survey the more recent developments, which include compact phase manipulation structures, superabsorption, and actively controllable metamaterials as well as the new directions on acoustic wave transport in moving fluid, elastic, and mechanical metamaterials, graphene-inspired metamaterials, and structures whose characteristics are best delineated by non-Hermitian Hamiltonians. Many of the novel acoustic metamaterial structures have transcended the original definition of metamaterials as arising from the collective manifestations of constituent resonating units, but they continue to extend wave manipulation functionalities beyond those found in nature. PMID:26933692

  10. Acoustic metamaterials: From local resonances to broad horizons.

    Ma, Guancong; Sheng, Ping

    2016-02-01

    Within a time span of 15 years, acoustic metamaterials have emerged from academic curiosity to become an active field driven by scientific discoveries and diverse application potentials. This review traces the development of acoustic metamaterials from the initial findings of mass density and bulk modulus frequency dispersions in locally resonant structures to the diverse functionalities afforded by the perspective of negative constitutive parameter values, and their implications for acoustic wave behaviors. We survey the more recent developments, which include compact phase manipulation structures, superabsorption, and actively controllable metamaterials as well as the new directions on acoustic wave transport in moving fluid, elastic, and mechanical metamaterials, graphene-inspired metamaterials, and structures whose characteristics are best delineated by non-Hermitian Hamiltonians. Many of the novel acoustic metamaterial structures have transcended the original definition of metamaterials as arising from the collective manifestations of constituent resonating units, but they continue to extend wave manipulation functionalities beyond those found in nature. PMID:26933692

  11. Soft resonator of omnidirectional resonance for acoustic metamaterials with a negative bulk modulus

    Xiaodong Jing; Yang Meng; Xiaofeng Sun

    2015-01-01

    Monopolar resonance is of fundamental importance in the acoustic field. Here, we present the realization of a monopolar resonance that goes beyond the concept of Helmholtz resonators. The balloon-like soft resonator (SR) oscillates omnidirectionally and radiates from all parts of its spherical surface, eliminating the need for a hard wall for the cavity and baffle effects. For airborne sound, such a low-modulus resonator can be made extremely lightweight. Deep subwavelength resonance is achie...

  12. Spin-(3/2) pentaquark resonance signature in lattice QCD

    The possible discovery of the Θ+ pentaquark has motivated a number of studies of its nature using lattice QCD. While all the analyses thus far have focused on spin-(1/2) states, here we report the results of the first exploratory study in quenched lattice QCD of pentaquarks with spin (3/2). For the spin-(3/2) interpolating field we use a product of the standard N and K* operators. We do not find any evidence for the standard lattice resonance signature of attraction (i.e., binding at quark masses near the physical regime) in the JP=(3/2)- channel. Some evidence of binding is inferred in the isoscalar (3/2)+ channel at several quark masses, in accord with the standard lattice resonance signature. This suggests that this is a good candidate for the further study of pentaquarks on the lattice

  13. Spin-3/2 pentaquark resonance signature in lattice QCD

    The possible discovery of the Θ+ pentaquark has motivated a number of studies of its nature using lattice QCD. While all the analyses thus far have focussed on spin-1/2 states, here we report the results of the first exploratory study in quenched lattice QCD of pentaquarks with spin 3/2. For the spin-3/2 interpolating field we use a product of the standard N and K* operators. We do not find any evidence for the standard lattice resonance signature of attraction (i.e., binding at quark masses near the physical regime) in the JP=(3-)/(2) channel. Some evidence of binding is inferred in the isoscalar (3+)/(2) channel at several quark masses, in accord with the standard lattice resonance signature. This suggests that this is a good candidate for the further study of pentaquarks on the lattice. (orig.)

  14. Acoustic detection of electron spin resonance

    Coufal, H.

    1981-07-01

    The ESR-signal of DPPH was recorded by detecting the modulation of the absorbed microwave power with a gas-coupled microphone. This photo-acoustic detection scheme is compared with conventional ESR-detection. Applications of the acoustical detection method to other modulation spectroscopic techniques, particularly NMR, are discussed.

  15. Effective zero index in locally resonant acoustic material

    Zhu, Xue-Feng, E-mail: ernestzhu.nju@gmail.com

    2013-10-30

    Here in locally resonant acoustic material, it is shown that effective zero refractive index can be constructed by the resonant unit-cells with coherent degenerate monopole–dipole momenta. Due to strong local resonances, the material layers with effective zero refractive index can function as a resonant cavity of high Q factor, where a subtle deviation from the resonant frequency may result in distinct increase of reflection. Full-wave simulations are performed to demonstrate some unusual wave transport properties such as invisibility cloaking, super-reflection, local field enhancement, and wavefronts rotation.

  16. Study on resonance frequency distribution of high-overtone bulk acoustic resonators

    ZHANG Hui; WANG Zuoqing; ZHANG Shuyi

    2005-01-01

    Based on the method of characterizing piezo-films by the resonance frequency distributions, the factors influencing the resonance frequency distribution of a High-overtone Bulk Acoustic Resonator (HBAR) consisting of a piezoelectric thin film with twoelectrodes and a substrate are studied. Some HBARs are simulated. The results manifest that changing the acoustic impedance ratio of the substrate to piezo-film the distribution of the space of the parallel resonance frequency and the effective electromechanical coupling factor are changed. When the fundamental mode of the piezo-film is at high frequency, changing the acoustic impedance ratio of the electrode to piezo-film and the thickness of the electrodes make the resonance frequency distribution of HBARs change. These results manifest that the HBARs can be resonant at specified frequencies by means of adjusting the factors affecting the resonance frequency distribution.

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

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

    2013-09-03

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

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

    Snively, J. B.

    2013-09-01

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

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

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

    2012-01-01

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

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

    Conde, Janine

    2009-01-01

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

  1. Ir/thz Double Resonance Signatures at Atmospheric Pressure

    Phillips, Dane J.; Tanner, Elizabeth A.; Everitt, Henry O.; Medvedev, Ivan R.; Neese, Christopher F.; Holt, Jennifer; De Lucia, Frank C.

    2010-06-01

    IR/THz double resonance (DR) spectroscopy, historically used to investigate molecular collision dynamics and THz molecular lasers at low pressures (remote sensing at atmospheric pressure. Molecular specificity is obtained through the rare coincidence(s) between molecule-specific ro-vibrational energy levels and CO2 laser lines. The resulting molecule-specific, DR-induced, THz spectroscopic signatures strongly depend on the type of ro-vibrational transition involved (P, Q, or R), the type of vibrational level excited (stretching or bending), and the molecular mass. To illustrate these sensitivities, calculated DR spectra of prototypical molecules such as methyl fluoride, methyl chloride, and methyl cyanide will be discussed. Although atmospheric pressure broadening obfuscates pure rotational spectra, we show how it can enhance the DR signature in two ways: by relaxing the pump coincidence requirement and by adding the DR signatures of multiple nearby transitions. We will present estimates of this enhancement, including cases where the coincidences that produce the strongest DR signatures at atmospheric pressure do not exist at low pressures.

  2. Particle manipulation by a non-resonant acoustic levitator

    Andrade, Marco A. B., E-mail: marcobrizzotti@gmail.com [Institute of Physics, University of São Paulo, CP 66318, 05314-970 São Paulo (Brazil); Pérez, Nicolás [Centro Universitario de Paysandú, Universidad de la República, Ruta 3 km 363, 60000 Paysandú (Uruguay); Adamowski, Julio C. [Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica, University of São Paulo, Av. Mello Moraes, 2231, 05508-030 São Paulo (Brazil)

    2015-01-05

    We present the analysis of a non-resonant acoustic levitator, formed by an ultrasonic transducer and a concave reflector. In contrast to traditional levitators, the geometry presented herein does not require the separation distance between the transducer and the reflector to be a multiple of half wavelength. The levitator behavior is numerically predicted by applying a numerical model to calculate the acoustic pressure distribution and the Gor'kov theory to obtain the potential of the acoustic radiation force that acts on a levitated particle. We also demonstrate that levitating particles can be manipulated by controlling the reflector position while maintaining the transducer in a fixed position.

  3. Particle manipulation by a non-resonant acoustic levitator

    Andrade, Marco A. B.; Pérez, Nicolás; Adamowski, Julio C.

    2015-01-01

    We present the analysis of a non-resonant acoustic levitator, formed by an ultrasonic transducer and a concave reflector. In contrast to traditional levitators, the geometry presented herein does not require the separation distance between the transducer and the reflector to be a multiple of half wavelength. The levitator behavior is numerically predicted by applying a numerical model to calculate the acoustic pressure distribution and the Gor'kov theory to obtain the potential of the acoustic radiation force that acts on a levitated particle. We also demonstrate that levitating particles can be manipulated by controlling the reflector position while maintaining the transducer in a fixed position.

  4. Particle manipulation by a non-resonant acoustic levitator

    We present the analysis of a non-resonant acoustic levitator, formed by an ultrasonic transducer and a concave reflector. In contrast to traditional levitators, the geometry presented herein does not require the separation distance between the transducer and the reflector to be a multiple of half wavelength. The levitator behavior is numerically predicted by applying a numerical model to calculate the acoustic pressure distribution and the Gor'kov theory to obtain the potential of the acoustic radiation force that acts on a levitated particle. We also demonstrate that levitating particles can be manipulated by controlling the reflector position while maintaining the transducer in a fixed position

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

    Aliza Aini Md Ralib

    2014-12-01

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

  6. Triad Resonance in the Gravity-Acoustic Family

    Kadri, U.

    2015-12-01

    Resonance interactions of waves play a prominent role in energy share among the different wave types involved. Such interactions may significantly contribute, among others, to the evolution of the ocean energy spectrum by exchanging energy between surface-gravity waves; surface and internal gravity waves; or even surface and compression-type waves, that can transfer energy from the upper ocean through the whole water column reaching down to the seafloor. A resonant triad occurs among a triplet of waves, usually involving interaction of nonlinear terms of second order perturbed equations. Until recently, it has been believed that in a homogeneous fluid a resonant triad is possible only when tension forces are included, or at the limit of a shallow water, and that when the compressibility of water is considered, no resonant triads can occur within the family of gravity-acoustic waves. However, more recently it has been proved that, under some circumstances, resonant triads comprising two opposing surface-gravity waves of similar periods (though not identical) and a much longer acoustic-gravity wave, of almost double the frequency, exist [Kadri and Stiassnie 2013, J. Fluid Mech.735 R6]. Here, I report on a new resonant triad involving a gravity wave and two acoustic waves of almost double the length. Interestingly, the two acoustic waves propagate in the same direction with similar wavelengths, that are almost double of that of the gravity wave. The evolution of the wave triad amplitudes is periodic and it is derived analytically, in terms of Jacobian elliptic functions and elliptic integrals. The physical importance of this type of triad interactions is the modulation of pertinent acoustic signals, leading to inaccurate signal perceptions. Enclosed figure: presents an example spatio-temporal evolution of the wave triad amplitudes. The gravity wave (top) remains almost unaltered, while the envelope slowly displaces to the left. However, the prescribed acoustic

  7. Acoustic superlens using Helmholtz-resonator-based metamaterials

    Yang, Xishan; Yin, Jing; Yu, Gaokun; Peng, Linhui; Wang, Ning

    2015-11-01

    Acoustic superlens provides a way to overcome the diffraction limit with respect to the wavelength of the bulk wave in air. However, the operating frequency range of subwavelength imaging is quite narrow. Here, an acoustic superlens is designed using Helmholtz-resonator-based metamaterials to broaden the bandwidth of super-resolution. An experiment is carried out to verify subwavelength imaging of double slits, the imaging of which can be well resolved in the frequency range from 570 to 650 Hz. Different from previous works based on the Fabry-Pérot resonance, the corresponding mechanism of subwavelength imaging is the Fano resonance, and the strong coupling between the neighbouring Helmholtz resonators separated at the subwavelength interval leads to the enhanced sound transmission over a relatively wide frequency range.

  8. Acoustic superlens using Helmholtz-resonator-based metamaterials

    Acoustic superlens provides a way to overcome the diffraction limit with respect to the wavelength of the bulk wave in air. However, the operating frequency range of subwavelength imaging is quite narrow. Here, an acoustic superlens is designed using Helmholtz-resonator-based metamaterials to broaden the bandwidth of super-resolution. An experiment is carried out to verify subwavelength imaging of double slits, the imaging of which can be well resolved in the frequency range from 570 to 650 Hz. Different from previous works based on the Fabry-Pérot resonance, the corresponding mechanism of subwavelength imaging is the Fano resonance, and the strong coupling between the neighbouring Helmholtz resonators separated at the subwavelength interval leads to the enhanced sound transmission over a relatively wide frequency range

  9. Acoustic superlens using Helmholtz-resonator-based metamaterials

    Yang, Xishan; Yin, Jing; Yu, Gaokun, E-mail: gkyu@ouc.edu.cn; Peng, Linhui; Wang, Ning [Department of Marine Technology, Ocean University of China, Qingdao 266100 (China)

    2015-11-09

    Acoustic superlens provides a way to overcome the diffraction limit with respect to the wavelength of the bulk wave in air. However, the operating frequency range of subwavelength imaging is quite narrow. Here, an acoustic superlens is designed using Helmholtz-resonator-based metamaterials to broaden the bandwidth of super-resolution. An experiment is carried out to verify subwavelength imaging of double slits, the imaging of which can be well resolved in the frequency range from 570 to 650 Hz. Different from previous works based on the Fabry-Pérot resonance, the corresponding mechanism of subwavelength imaging is the Fano resonance, and the strong coupling between the neighbouring Helmholtz resonators separated at the subwavelength interval leads to the enhanced sound transmission over a relatively wide frequency range.

  10. Effect of a cracked surface of porous silicon on the behaviour of the acoustic signature

    Bouhedja Samia

    2014-06-01

    Full Text Available We study in this work the effect of a crack, located on the porous silicon, Psi, surface on the propagation of Rayleigh waves. We simulate and analyse the acoustic signature V(z according porosity at 142 MHz, to study the microstructure of PSi around the crack.

  11. Resonance Shift of Single-Axis Acoustic Levitation

    XIE Wen-Jun; WEI Bing-Bo

    2007-01-01

    @@ The resonance shift due to the presence and movement of a rigid spherical sample in a single-axis acoustic levitator is studied with the boundary element method on the basis of a two-cylinder model of the levitator.The introduction of a sample into the sound pressure nodes, where it is usually levitated, reduces the resonant interval Hn (n is the mode number) between the reflector and emitter.

  12. Resonance and Nonlinear Seismo-Acoustic Land Mine Detection

    Donskoy, Dimitri M.

    2008-01-01

    We have presented an overview of our team’s (at Stevens Institute of Technology) contribution in development of resonance and nonlinear Seismo-Acoustic Mine Detection (SAMD) techniques. Among our major accomplishments are the discovery and quantitative characterization of mine resonances; the discovery of a very strong nonlinear dynamics of the buried mines manifesting itself through the combination and intermodulation frequencies; the development of a physical model describing the linear a...

  13. Quantitative Determination of Lateral Mode Dispersion in Film Bulk Acoustic Resonators through Laser Acoustic Imaging

    Ken Telschow; John D. Larson III

    2006-10-01

    Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowledge of their operation properties are needed to optimize their design for specific applications. The finite size of these resonators precludes their use in single acoustic modes; rather, multiple wave modes, such as, lateral wave modes are always excited concurrently. In order to determine the contributions of these modes, we have been using a newly developed full-field laser acoustic imaging approach to directly measure their amplitude and phase throughout the resonator. This paper describes new results comparing modeling of both elastic and piezoelectric effects in the active material with imaging measurement of all excited modes. Fourier transformation of the acoustic amplitude and phase displacement images provides a quantitative determination of excited mode amplitude and wavenumber at any frequency. Images combined at several frequencies form a direct visualization of lateral mode excitation and dispersion for the device under test allowing mode identification and comparison with predicted operational properties. Discussion and analysis are presented for modes near the first longitudinal thickness resonance (~900 MHz) in an AlN thin film resonator. Plate wave modeling, taking account of material crystalline orientation, elastic and piezoelectric properties and overlayer metallic films, will be discussed in relation to direct image measurements.

  14. Modeling the acoustic excitation of a resonator

    Mandre, Shreyas; Mahadevan, Lakshminarayanan

    2007-11-01

    The sounding of a beverage bottle when blown on is a familiar but very little understood phenomenon. A very similar mechanism is used by musical wind instruments, like organ pipes and flutes, for sound production. This phenomenon falls under the general umbrella of flow induced oscillations and is representative of a more generic mechanism. The modeling of this phenomenon essentially involves two components. The first is the resonator, which bears the oscillations and this component is very well understood. The resonator, however, needs an external energy input to sustain the oscillations, which is provided by the jet of air blown. The dynamics of the jet and its interaction with the resonator is the primary focus of this talk. In particular, we provide a linearized model based on first principles to explain the feedback of energy from the jet to the resonator and compare the predictions with experimental results.

  15. Bound states in the continuum in open acoustic resonators

    Lyapina, A A; Pilipchuk, A S; Sadreev, A F

    2015-01-01

    We consider bound states in the continuum (BSC) or embedded trapped modes in two- and three-dimensional acoustic axisymmetric duct-cavity structures. We demonstrate numerically that under variation of the length of the cavity multiple BSCs occur due to the Friedrich-Wintgen two-mode full destructive interference mechanism. The BSCs are detected by tracing the resonant widths to the points of the collapse of Fano resonances where one of the two resonant modes acquires infinite life-time. It is shown that the approach of the acoustic coupled mode theory cast in the truncated form of a two-mode approximation allows us to analytically predict the BSC frequencies and shape functions to a good accuracy in both two and three dimensions.

  16. Harnessing buckling to design tunable locally resonant acoustic metamaterials.

    Wang, Pai; Casadei, Filippo; Shan, Sicong; Weaver, James C; Bertoldi, Katia

    2014-07-01

    We report a new class of tunable and switchable acoustic metamaterials comprising resonating units dispersed into an elastic matrix. Each resonator consists of a metallic core connected to the elastomeric matrix through elastic beams, whose buckling is intentionally exploited as a novel and effective approach to control the propagation of elastic waves. We first use numerical analysis to show the evolution of the locally resonant band gap, fully accounting for the effect of nonlinear pre-deformation. Then, we experimentally measure the transmission of vibrations as a function of the applied loading in a finite-size sample and find excellent agreement with our numerical predictions. The proposed concept expands the ability of existing acoustic metamaterials by enabling tunability over a wide range of frequencies. Furthermore, we demonstrate that in our system the deformation can be exploited to turn on or off the band gap, opening avenues for the design of adaptive switches. PMID:25032927

  17. Laser Acoustic Imaging of Film Bulk Acoustic Resonator (FBAR) Lateral Mode Dispersion

    Ken L. Telschow

    2004-07-01

    A laser acoustic imaging microscope has been developed that measures acoustic motion with high spatial resolution without scanning. Images are recorded at normal video frame rates and heterodyne principles are used to allow operation at any frequency from Hz to GHz. Fourier transformation of the acoustic amplitude and phase displacement images provides a direct quantitative determination of excited mode wavenumbers at any frequency. Results are presented at frequencies near the first longitudinal thickness mode (~ 900 MHz) demonstrating simultaneous excitation of lateral modes with nonzero wavenumbers in an electrically driven AlN thin film acoustic resonator. Images combined at several frequencies form a direct visualization of lateral mode dispersion relations for the device under test allowing mode identification and a direct measure of specific lateral mode properties. Discussion and analysis of the results are presented in comparison with plate wave modeling of these devices taking account for material anisotropy and multilayer films.

  18. Acoustic noise in magnetic resonance imaging: An ongoing issue

    Purpose: Acoustic noise creates a problem for both patients and staff within the magnetic resonance (MR) environment. This study qualitatively and quantitatively investigates the acoustic noise levels from two MR systems in one clinical department and demonstrates the adverse effects that the acoustic noise generated in magnetic resonance imaging (MRI) has on a patient's experience of an MRI examination. Methods: A questionnaire was distributed to consenting patients undergoing one of two specific MR examinations on two MR systems (System A and System B) of varying age and technology in one clinical department. These evaluated the patient's experience during the MRI examination. Physical measurements of the maximum acoustic noise levels produced by each system for various pulse sequences were also recorded using a sound level meter. Results: The results of the questionnaire survey demonstrated significantly greater tolerance of the acoustic noise levels of System B (mean noise level rating of 2.45 on LIKERT scale) in comparison to System A (mean noise level rating of 3.71 on LIKERT scale) (P = 0.001). Significantly lower noise level descriptions were also demonstrated (P = 0.01). The maximum recorded sound levels also confirmed that System B was quieter than the System A. Conclusion: It is has been demonstrated that the acoustic noise generated during an MRI examinations has an adverse effect on the patient experience during the examination. However, new technology has significantly reduced these effects and is improving patient comfort in MRI. It was shown quantitatively that the newer system's advanced gradient technology was quieter than the older system, in terms of the acoustic noise levels associated with a range of common pulse sequences.

  19. Acoustic resonance in heat exchanger tube bundles - Part II: Prediction and suppression of resonance

    In the first part of this series, experimental data were presented which suggest that the acoustic resonance in heat exchanger tube bundles is tied to periodic vortex shedding from the tubes. In this paper, a semiempirical model for predicting the onset of resonance is developed. This model is compared with experimental data and other models from the literature. Methods of suppressing the resonance are developed and experimental data on their effectiveness are presented

  20. Identification of cavitation signatures using both optical and PZT acoustic sensors

    Vidakovic, M.; Armakolas, I.; Sun, T.; Carlton, J.; Grattan, K. T. V.

    2015-09-01

    This paper presents the results obtained from monitoring a simulated material cavitation process using both a fibre Bragg grating (FBG)-based acoustic sensor system developed at City University London and a commercial PZT (Piezoelectric Transducer) acoustic sensor, with an aim to identify the cavitation signatures. In the experiment, a sample metal plate with its back surface being instrumented with both sensors is positioned very close to an excitation sonotrode with a standard frequency of 19.5kHz. The data obtained from both sensors are recorded and analyzed, showing a very good agreement.

  1. Spontaneous pattern formation in an acoustical resonator

    Sanchez-Morcillo, Victor J.

    2003-01-01

    A dynamical system of equations describing parametric sound generation (PSG) in a dispersive large aspect ratio resonator is derived. The model generalizes previously proposed descriptions of PSG by including diffraction effects, and is analogous to the model used in theoretical studies of optical parametric oscillation. A linear stability analysis of the solution below the threshold of subharmonic generation reveals the existence of a pattern forming instability, which is confirmed by numeri...

  2. Flow-excited acoustic resonance of a Helmholtz resonator: Discrete vortex model compared to experiments

    The acoustic resonance in a Helmholtz resonator excited by a low Mach number grazing flow is studied theoretically. The nonlinear numerical model is established by coupling the vortical motion at the cavity opening with the cavity acoustic mode through an explicit force balancing relation between the two sides of the opening. The vortical motion is modeled in the potential flow framework, in which the oscillating motion of the thin shear layer is described by an array of convected point vortices, and the unsteady vortex shedding is determined by the Kutta condition. The cavity acoustic mode is obtained from the one-dimensional acoustic propagation model, the time-domain equivalent of which is given by means of a broadband time-domain impedance model. The acoustic resistances due to radiation and viscous loss at the opening are also taken into account. The physical processes of the self-excited oscillations, at both resonance and off-resonance states, are simulated directly in the time domain. Results show that the shear layer exhibits a weak flapping motion at the off-resonance state, whereas it rolls up into large-scale vortex cores when resonances occur. Single and dual-vortex patterns are observed corresponding to the first and second hydrodynamic modes. The simulation also reveals different trajectories of the two vortices across the opening when the first and second hydrodynamic modes co-exist. The strong modulation of the shed vorticity by the acoustic feedback at the resonance state is demonstrated. The model overestimates the pressure pulsation amplitude by a factor 2, which is expected to be due to the turbulence of the flow which is not taken into account. The model neglects vortex shedding at the downstream and side edges of the cavity. This will also result in an overestimation of the pulsation amplitude

  3. Flow-excited acoustic resonance of a Helmholtz resonator: Discrete vortex model compared to experiments

    Dai, Xiwen; Jing, Xiaodong, E-mail: jingxd@buaa.edu.cn; Sun, Xiaofeng [School of Energy and Power Engineering, Beihang University, Beijing 100191 (China)

    2015-05-15

    The acoustic resonance in a Helmholtz resonator excited by a low Mach number grazing flow is studied theoretically. The nonlinear numerical model is established by coupling the vortical motion at the cavity opening with the cavity acoustic mode through an explicit force balancing relation between the two sides of the opening. The vortical motion is modeled in the potential flow framework, in which the oscillating motion of the thin shear layer is described by an array of convected point vortices, and the unsteady vortex shedding is determined by the Kutta condition. The cavity acoustic mode is obtained from the one-dimensional acoustic propagation model, the time-domain equivalent of which is given by means of a broadband time-domain impedance model. The acoustic resistances due to radiation and viscous loss at the opening are also taken into account. The physical processes of the self-excited oscillations, at both resonance and off-resonance states, are simulated directly in the time domain. Results show that the shear layer exhibits a weak flapping motion at the off-resonance state, whereas it rolls up into large-scale vortex cores when resonances occur. Single and dual-vortex patterns are observed corresponding to the first and second hydrodynamic modes. The simulation also reveals different trajectories of the two vortices across the opening when the first and second hydrodynamic modes co-exist. The strong modulation of the shed vorticity by the acoustic feedback at the resonance state is demonstrated. The model overestimates the pressure pulsation amplitude by a factor 2, which is expected to be due to the turbulence of the flow which is not taken into account. The model neglects vortex shedding at the downstream and side edges of the cavity. This will also result in an overestimation of the pulsation amplitude.

  4. Scaling of membrane-type locally resonant acoustic metamaterial arrays.

    Naify, Christina J; Chang, Chia-Ming; McKnight, Geoffrey; Nutt, Steven R

    2012-10-01

    Metamaterials have emerged as promising solutions for manipulation of sound waves in a variety of applications. Locally resonant acoustic materials (LRAM) decrease sound transmission by 500% over acoustic mass law predictions at peak transmission loss (TL) frequencies with minimal added mass, making them appealing for weight-critical applications such as aerospace structures. In this study, potential issues associated with scale-up of the structure are addressed. TL of single-celled and multi-celled LRAM was measured using an impedance tube setup with systematic variation in geometric parameters to understand the effects of each parameter on acoustic response. Finite element analysis was performed to predict TL as a function of frequency for structures with varying complexity, including stacked structures and multi-celled arrays. Dynamic response of the array structures under discrete frequency excitation was investigated using laser vibrometry to verify negative dynamic mass behavior. PMID:23039544

  5. Blend uniformity analysis of pharmaceutical products by Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS).

    Fitzpatrick, Dara; Scanlon, Eoin; Krüse, Jacob; Vos, Bastiaan; Evans-Hurson, Rachel; Fitzpatrick, Eileen; McSweeney, Seán

    2012-11-15

    Blend uniformity analysis (BUA) is a routine and highly regulated aspect of pharmaceutical production. In most instances, it involves quantitative determination of individual components of a blend in order to ascertain the mixture ratio. This approach often entails the use of costly and sophisticated instrumentation and complex statistical methods. In this study, a new and simple qualitative blend confirmatory test is introduced based on a well known acoustic phenomenon. Several over the counter (OTC) product powder blends are analysed and it is shown that each product has a unique and highly reproducible acoustic signature. The acoustic frequency responses generated during the dissolution of the product are measured and recorded in real time. It is shown that intra-batch and inter-batch variation for each product is either insignificant or non-existent when measured in triplicate. This study demonstrates that Broadband Acoustic Resonance Dissolution Spectroscopy or BARDS can be used successfully to determine inter-batch variability, stability and uniformity of powder blends. This is just one application of a wide range of BARDS applications which are more cost effective and time efficient than current methods. PMID:22884840

  6. Homogenation of acoustic metamaterials of Helmholtz resonators in fluid

    Hu, X.; Ho, K. M.; Chan, C. T.; Zi, J.

    2008-05-01

    By using a two-step homogenization approach, we derive analytical formulas of effective mass density {rho}{sub e} and effective bulk modulus B{sub e} for two- and three-dimensional acoustic metamaterials of Helmholtz resonators (HRs) in fluid. A negative B{sub e} is found at certain frequencies due to the monopolar resonance, leading to a low-frequency acoustic band gap. A unified picture is presented for metamaterials of HRs and three-component metamaterials of negative {rho}{sub e}. Our work supports recent observations in a one-dimensional array of HRs [N. Fang et al., Nat. Mater. 5, 452 (2006)] and presents important high-dimensional extensions for exploring more fascinating phenomena.

  7. Acoustic resonance in MEMS scale cylindrical tubes with side branches

    Schill, John F.; Holthoff, Ellen L.; Pellegrino, Paul M.; Marcus, Logan S.

    2014-05-01

    Photoacoustic spectroscopy (PAS) is a useful monitoring technique that is well suited for trace gas detection. This method routinely exhibits detection limits at the parts-per-million (ppm) or parts-per-billion (ppb) level for gaseous samples. PAS also possesses favorable detection characteristics when the system dimensions are scaled to a microelectromechanical system (MEMS) design. One of the central issues related to sensor miniaturization is optimization of the photoacoustic cell geometry, especially in relationship to high acoustical amplification and reduced system noise. Previous work relied on a multiphysics approach to analyze the resonance structures of the MEMS scale photo acoustic cell. This technique was unable to provide an accurate model of the acoustic structure. In this paper we describe a method that relies on techniques developed from musical instrument theory and electronic transmission line matrix methods to describe cylindrical acoustic resonant cells with side branches of various configurations. Experimental results are presented that demonstrate the ease and accuracy of this method. All experimental results were within 2% of those predicted by this theory.

  8. Active Cancellation of Acoustical Resonances with an FPGA FIR Filter

    Ryou, Albert; Simon, Jonathan

    2016-05-01

    We demonstrate a novel approach to enhancing the closed-loop bandwidth of a feedback-controlled mechanical system by digitally cancelling its acoustical resonances and antiresonances with an FPGA FIR filter. By performing a real-time convolution of the feedback error signal with an arbitrary filter, we can suppress arbitrarily many poles and zeros below 100 kHz, each with a linewidth as small as 10 Hz. We demonstrate the efficacy of this technique by cancelling the six largest resonances and antiresonances of a high-finesse optical resonator piezomechanical transfer function, thereby enhancing the unity gain frequency by more than an order of magnitude. More broadly, this approach is applicable to stabilization of optical resonators, external cavity diode lasers, and scanning tunneling microscopes.

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

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

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

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

    2014-11-21

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

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

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

  12. Acoustic agglomeration of fine particles based on a high intensity acoustical resonator

    Zhao, Yun; Zeng, Xinwu; Tian, Zhangfu

    2015-10-01

    Acoustic agglomeration (AA) is considered to be a promising method for reducing the air pollution caused by fine aerosol particles. Removal efficiency and energy consuming are primary parameters and generally have a conflict with each other for the industry applications. It was proved that removal efficiency is increased with sound intensity and optimal frequency is presented for certain polydisperse aerosol. As a result, a high efficiency and low energy cost removal system was constructed using acoustical resonance. High intensity standing wave is generated by a tube system with abrupt section driven by four loudspeakers. Numerical model of the tube system was built base on the finite element method, and the resonance condition and SPL increase were confirmd. Extensive tests were carried out to investigate the acoustic field in the agglomeration chamber. Removal efficiency of fine particles was tested by the comparison of filter paper mass and particle size distribution at different operating conditions including sound pressure level (SPL), and frequency. The experimental study has demonstrated that agglomeration increases with sound pressure level. Sound pressure level in the agglomeration chamber is between 145 dB and 165 dB from 500 Hz to 2 kHz. The resonance frequency can be predicted with the quarter tube theory. Sound pressure level gain of more than 10 dB is gained at resonance frequency. With the help of high intensity sound waves, fine particles are reduced greatly, and the AA effect is enhanced at high SPL condition. The optimal frequency is 1.1kHz for aerosol generated by coal ash. In the resonace tube, higher resonance frequencies are not the integral multiplies of the first one. As a result, Strong nonlinearity is avoided by the dissonant characteristic and shock wave is not found in the testing results. The mechanism and testing system can be used effectively in industrial processes in the future.

  13. Acoustic signature recognition technique for Human-Object Interactions (HOI) in persistent surveillance systems

    Alkilani, Amjad; Shirkhodaie, Amir

    2013-05-01

    Handling, manipulation, and placement of objects, hereon called Human-Object Interaction (HOI), in the environment generate sounds. Such sounds are readily identifiable by the human hearing. However, in the presence of background environment noises, recognition of minute HOI sounds is challenging, though vital for improvement of multi-modality sensor data fusion in Persistent Surveillance Systems (PSS). Identification of HOI sound signatures can be used as precursors to detection of pertinent threats that otherwise other sensor modalities may miss to detect. In this paper, we present a robust method for detection and classification of HOI events via clustering of extracted features from training of HOI acoustic sound waves. In this approach, salient sound events are preliminary identified and segmented from background via a sound energy tracking method. Upon this segmentation, frequency spectral pattern of each sound event is modeled and its features are extracted to form a feature vector for training. To reduce dimensionality of training feature space, a Principal Component Analysis (PCA) technique is employed to expedite fast classification of test feature vectors, a kd-tree and Random Forest classifiers are trained for rapid classification of training sound waves. Each classifiers employs different similarity distance matching technique for classification. Performance evaluations of classifiers are compared for classification of a batch of training HOI acoustic signatures. Furthermore, to facilitate semantic annotation of acoustic sound events, a scheme based on Transducer Mockup Language (TML) is proposed. The results demonstrate the proposed approach is both reliable and effective, and can be extended to future PSS applications.

  14. Acoustic resonances in two dimensional radial sonic crystals shells

    Torrent, Daniel

    2010-01-01

    Radial sonic crystals (RSC) are fluidlike structures infinitely periodic along the radial direction. They have been recently introduced and are only possible thanks to the anisotropy of specially designed acoustic metamaterials [see Phys. Rev. Lett. {\\bf 103} 064301 (2009)]. We present here a comprehensive analysis of two-dimensional RSC shells, which consist of a cavity defect centered at the origin of the crystal and a finite thickness crystal shell surrounded by a fluidlike background. We develop analytic expressions demonstrating that, like for other type of crystals (photonic or phononic) with defects, these shells contain Fabry-Perot like resonances and strongly localized modes. The results are completely general and can be extended to three dimensional acoustic structures and to their photonic counterparts, the radial photonic crystals.

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

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

  16. Soft resonator of omnidirectional resonance for acoustic metamaterials with a negative bulk modulus

    Jing, Xiaodong; Meng, Yang; Sun, Xiaofeng

    2015-11-01

    Monopolar resonance is of fundamental importance in the acoustic field. Here, we present the realization of a monopolar resonance that goes beyond the concept of Helmholtz resonators. The balloon-like soft resonator (SR) oscillates omnidirectionally and radiates from all parts of its spherical surface, eliminating the need for a hard wall for the cavity and baffle effects. For airborne sound, such a low-modulus resonator can be made extremely lightweight. Deep subwavelength resonance is achieved when the SR is tuned by adjusting the shell thickness, benefiting from the large density contrast between the shell material and the encapsulated gas. The SR resonates with near-perfect monopole symmetry, as demonstrated by the theoretical and experimental results, which are in excellent agreement. For a lattice of SRs, a band gap occurs and blocks near-total transmission, and the effective bulk modulus exhibits a prominent negative band, while the effective mass density remains unchanged. Our study shows that the SR is suitable for building 3D acoustic metamaterials and provides a basis for constructing left-handed materials as a new means of creating a negative bulk modulus.

  17. Micro acoustic resonant chambers for heating/agitating/mixing (MARCHAM)

    Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita M.; Takano, Nobuyuki; Grunthaner, Frank

    2016-04-01

    A variety of applications require the mixing and/or heating of a slurry made from a powder/fluid mixture. One of these applications, Sub Critical Water Extraction (SCWE), is a process where water and an environmental powder sample (sieved soil, drill cuttings, etc.) are heated in a sealed chamber to temperatures greater than 200 degrees Celsius by allowing the pressure to increase, but without reaching the critical point of water. At these temperatures, the ability of water to extract organics from solid particulate increases drastically. This paper describes the modeling and experimentation on the use of an acoustic resonant chamber which is part of an amino acid detection instrument called Astrobionibbler [Noell et al. 2014, 2015]. In this instrument we use acoustics to excite a fluid- solid fines mixture in different frequency/amplitude regimes to accomplish a variety of sample processing tasks. Driving the acoustic resonant chamber at lower frequencies can create circulation patterns in the fluid and mixes the liquid and fines, while driving the chamber at higher frequencies one can agitate the fluid and powder and create a suspension. If one then drives the chamber at high amplitude at resonance heating of the slurry occurs. In the mixing and agitating cell the particle levitation force depends on the relative densities and compressibility's of the particulate and fluid and on the kinetic and potential energy densities associated with the velocity and pressure fields [Glynne-Jones, Boltryk and Hill 2012] in the cell. When heating, the piezoelectric transducer and chamber is driven at high power in resonance where the solid/fines region is modelled as an acoustic transmission line with a large loss component. In this regime, heat is pumped into the solution/fines mixture and rapidly heats the sample. We have modeled the piezoelectric transducer/chamber/ sample using Mason's equivalent circuit. In order to assess the validity of the model we have built and

  18. Acoustic resonances in two-dimensional radial sonic crystal shells

    Radial sonic crystals (RSC) are fluidlike structures infinitely periodic along the radial direction that verify the Bloch theorem and are possible only if certain specially designed acoustic metamaterials with mass density anisotropy can be engineered (see Torrent and Sanchez-Dehesa 2009 Phys. Rev. Lett. 103 064301). A comprehensive analysis of two-dimensional (2D) RSC shells is reported here. A given shell is in fact a circular slab with a central cavity. These finite crystal structures contain Fabry-Perot-like resonances and modes strongly localized at the central cavity. Semi-analytical expressions are developed to obtain the quality factors of the different resonances, their symmetry features and their excitation properties. The results reported here are completely general and can be extended to equivalent 3D spherical shells and to their photonic counterparts.

  19. Acoustic resonances in two-dimensional radial sonic crystal shells

    Torrent, Daniel; Sanchez-Dehesa, Jose, E-mail: jsdehesa@upvnet.upv.e [Wave Phenomena Group, Departamento de Ingenieria Electronica, Universidad Politecnica de Valencia, C/Camino de Vera s.n., E-46022 Valencia (Spain)

    2010-07-15

    Radial sonic crystals (RSC) are fluidlike structures infinitely periodic along the radial direction that verify the Bloch theorem and are possible only if certain specially designed acoustic metamaterials with mass density anisotropy can be engineered (see Torrent and Sanchez-Dehesa 2009 Phys. Rev. Lett. 103 064301). A comprehensive analysis of two-dimensional (2D) RSC shells is reported here. A given shell is in fact a circular slab with a central cavity. These finite crystal structures contain Fabry-Perot-like resonances and modes strongly localized at the central cavity. Semi-analytical expressions are developed to obtain the quality factors of the different resonances, their symmetry features and their excitation properties. The results reported here are completely general and can be extended to equivalent 3D spherical shells and to their photonic counterparts.

  20. The thermophysical properties of gases determined using an annular acoustic resonator

    Buxton, A. J.

    1997-01-01

    A novel annular acoustic resonator was constructed for measurements of the speed of sound in gases at pressures below 1 MPa. The resonator was designed to allow measurements of the speed and absorption of sound at low pressure in gases with large bulk viscosities. Measurements in propene, for which the speed of sound is known, served to characterise the geometry of the resonator and provide a test of the acoustic model for the system. A detailed description of the resonator whi...

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

    Siegfried Hohmann

    2015-05-01

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

  2. Film bulk acoustic resonator pressure sensor with self temperature reference

    A novel film bulk acoustic resonator (FBAR) with two resonant frequencies which have opposite reactions to temperature changes has been designed. The two resonant modes respond differently to changes in temperature and pressure, with the frequency shift being linearly correlated with temperature and pressure changes. By utilizing the FBAR's sealed back trench as a cavity, an on-chip single FBAR sensor suitable for measuring pressure and temperature simultaneously is proposed and demonstrated. The experimental results show that the pressure coefficient of frequency for the lower frequency peak of the FBAR sensors is approximately −17.4 ppm kPa−1, while that for the second peak is approximately −6.1 ppm kPa−1, both of them being much more sensitive than other existing pressure sensors. This dual mode on-chip pressure sensor is simple in structure and operation, can be fabricated at very low cost, and yet requires no specific package, therefore has great potential for applications. (paper)

  3. Implementation of electromagnetic acoustic resonance in pipe inspection

    Electromagnetic acoustic resonance (EMAR) provides accurate and stable evaluation. Its capability has been demonstrated through online monitoring using a large-scale corrosion test loop operating at high temperature. This study uses EMAR to evaluate the thickness of pipes in a nuclear power plant during its shutdown through signal processing based on superposition of nth compression. Sections of piping evaluated with EMAR include those in long-term service, where thinning may produce scale-like surfaces, and those having complicated geometry. Moreover, we compare measurement results obtained with EMAR and with ultrasonic testing (UT). The accuracy of EMAR depends on the pipe geometry, such as the pipe diameter and whether the pipe is straight or an elbow, the presence of welding, and complicated wall thinning. We consider the causes of the difference in thickness values between EMAR measurements and UT. Finally, we discuss how to implement EMAR in pipe inspection. (author)

  4. Implementation applicability of piping inspection using electromagnetic acoustic resonance

    The electromagnetic acoustic resonance (EMAR) method provides accurate and stable evaluation and its capability has been demonstrated through online monitoring using a large-scale corrosion test loop in operation at high temperature. This study applies EMAR with the signal processing method of the superposition of nth compression to the thickness evaluation of piping in a nuclear power plant during shutdown. Sections of piping evaluated by EMAR include those having long-term service, where thinning may produce scale-like surfaces, and those having complicated geometry. Moreover, measurement results obtained with EMAR and in ultrasonic testing are compared. The accuracy of the EMAR method depends on the pipe geometry, such as the pipe diameter and whether the pipe is straight or an elbow, the presence of welding, and complicated wall thinning. (author)

  5. RAP: acoustic detection of particles in ultracryogenic resonant antenna

    Bertolucci, S.; Coccia, E.; D' Antonio, S.; Waard, A. de; Delle Monache, G.; Di Gioacchino, D.; Fafone, V.; Fauth, A.; Frossati, G.; Ligi, C. E-mail: carlo.ligi@inf.infn.it; Marini, A.; Mazzitelli, G.; Modestino, G.; Pizzella, G.; Quintieri, L.; Raffone, G.; Ronga, F.; Tripodi, P.; Valente, P

    2004-03-11

    The resonant-mass gravitational wave detector NAUTILUS has recently recorded signals due to cosmic rays crossing. Very large signals have been observed in the superconductive state of the antenna. In order to investigate this anomalous response at low temperatures, the Rivelazione Acustica di Particelle experiment has been approved. Its purpose is the measurement of the mechanical vibrations in a superconducting (T{approx}100 mK) cylindrical aluminium bar when hit by 10{sup 5} electrons at 510 MeV from the DAPHINE Beam Test Facility, corresponding to the energies released by extensive air showers in the NAUTILUS antenna. The results of this measurement are crucial to understand the interaction of ionizing particles with bulk superconductors and to confirm the results on the thermo-acoustic model of the past experiments.

  6. CMOS-Integrated Film Bulk Acoustic Resonators for Label-Free Biosensing

    Matthias Schreiter

    2010-04-01

    Full Text Available The throughput is an important parameter for label-free biosensors. Acoustic resonators like the quartz crystal microbalance have a low throughput because the number of sensors which can be used at the same time is limited. Here we present an array of 64 CMOS-integrated film bulk acoustic resonators. We compare the performance with surface plasmon resonance and the quartz crystal microbalance and demonstrate the performance of the sensor for multiplexed detection of DNA.

  7. Search for new resonances with boosted signatures at CMS

    CERN. Geneva

    2015-01-01

    The LHC and its experiments are ideally suited to search for these new resonances in order to validate or constrain the corresponding theories. At resonance masses well above 1 TeV, these searches face specific challenges. The decay products have large Lorentz boosts, resulting in very collimated final state topologies. Jet substructure methods and the use of non-isolate...

  8. The underwater acoustic signature of a nuclear explosion at the ocean surface. Interim technical report

    Bache, T.C.; Barker, T.G.; Brown, M.G.; Pyatt, K.D.; Swanger, H.J.

    1980-07-01

    The gross spectral character and duration of the acoustic wave signature of a nuclear explosion near the ocean surface is estimated by constructing theoretical pressure-time histories, using models for the explosion and wave propagation. The explosion is assumed to have a yield of 1 KT and the nominal range is 6600 km. The frequencies of interest are rather low, 50 Hz and less, so absorption is small and the estimates of spectral character and duration essentially decouple. The spectrum depends almost entirely on the source characteristics and the duration is controlled by characteristics of the travel path. The airblast-induced pressure loading on the ocean surface dominates the source, with the acoustic waves from direct coupling into the water being relatively small. At large distances, the spectrum for 1 KT peaks near 20 Hz and is band-limited between 5 and 50 Hz. For different energy yields these frequencies scale with the cube-root of the yield. Different assumptions about the (laterally homogeneous) oceanic sound profile lead to differing estimates for the signal duration. Values of 20 to 60 seconds seem most reasonable.

  9. Analysis of acoustic resonator with shape deformation using finite element method

    G M Kalmse; Ajay Chaudhari; P B Patil

    2000-10-01

    An acoustic resonator with shape deformation has been analysed using the finite element method. The shape deformation issuch that the volume of the resonator remains constant. The effect of deformation on the resonant frequencies is studied. Deformation splits the degenerate frequencies.

  10. Quantum signatures of nonlinear resonances in mesoscopic systems: Efficient extension of localized wave functions

    We investigate the quantum signatures of classical nonlinear resonances by making the analytic connection between the quantum wave functions and the classical periodic orbits for the uncoupled systems. It is found that the highly efficient extension of the localized coherent states within the classical caustics is an intriguing phenomenon in mesoscopic systems with nonlinear resonances. With the theoretical analysis, we experimentally demonstrate that the laser resonator with an intracavity saturable absorber can be employed to visualize the wave patterns analogous to the quantum wave functions associated with Fermi resonance

  11. Search for the pentaquark resonance signature in lattice QCD

    B. G. Lasscock; J. Hedditch; D. B. Leinweber; W. Melnitchouk; A. W. Thomas; A. G. Williams; R. D. Young; J. M. Zanotti

    2005-03-01

    Claims concerning the possible discovery of the $\\Theta^+$ pentaquark, with minimal quark content $uudd\\bar{s}$, have motivated our comprehensive study into possible pentaquark states using lattice QCD. We review various pentaquark interpolating fields in the literature and create a new candidate ideal for lattice QCD simulations. Using these interpolating fields we attempt to isolate a signal for a five-quark resonance. Calculations are performed using improved actions on a large $20^{3} \\times 40$ lattice in the quenched approximation. The standard lattice resonance signal of increasing attraction between baryon constituents for increasing quark mass is not observed for spin-1/2 pentaquark states. We conclude that evidence supporting the existence of a spin-1/2 pentaquark resonance does not exist in quenched QCD.

  12. Characterization of Acoustic Resonance in a High-Pressure Sodium Lamp

    Chhun, Labo; Maussion, Pascal; Bhosle, Sounil; Zissis, Georges

    2011-01-01

    International audience With the last decades, the high pressure sodium (HPS) lamp has been supplied in high frequency in order to increase the efficacy of the lamp/ballast system. However, at some given frequencies, standing acoustic waves, namely acoustic resonance (AR), might develop in the burner and cause lamp luminous fluctuation, extinction and destruction in the most serious case. As we seek for a control method to detect and avoid the lamp AR some main characteristics of the acoust...

  13. Implementation of algorithms to discriminate chemical/biological airbursts from high explosive airbursts utilizing acoustic signatures

    Hohil, Myron E.; Desai, Sachi; Morcos, Amir

    2006-05-01

    The Army is currently developing acoustic sensor systems that will provide extended range surveillance, detection, and identification for force protection and tactical security. A network of such sensors remotely deployed in conjunction with a central processing node (or gateway) will provide early warning and assessment of enemy threats, near real-time situational awareness to commanders, and may reduce potential hazards to the soldier. In contrast, the current detection of chemical/biological (CB) agents expelled into a battlefield environment is limited to the response of chemical sensors that must be located within close proximity to the CB agent. Since chemical sensors detect hazardous agents through contact, the sensor range to an airburst is the key-limiting factor in identifying a potential CB weapon attack. The associated sensor reporting latencies must be minimized to give sufficient preparation time to field commanders, who must assess if an attack is about to occur, has occurred, or if occurred, the type of agent that soldiers might be exposed to. The long-range propagation of acoustic blast waves from heavy artillery blasts, which are typical in a battlefield environment, introduces a feature for using acoustics and other sensor suite technologies for the early detection and identification of CB threats. Employing disparate sensor technologies implies that warning of a potential CB attack can be provided to the solider more rapidly and from a safer distance when compared to current conventional methods. Distinct characteristics arise within the different airburst signatures because High Explosive (HE) warheads emphasize concussive and shrapnel effects, while chemical/biological warheads are designed to disperse their contents over immense areas, therefore utilizing a slower burning, less intensive explosion to mix and distribute their contents. Highly reliable discrimination (100%) has been demonstrated at the Portable Area Warning Surveillance System

  14. Signatures of resonant terrestrial planets in long-period systems

    Kennedy, Gareth F

    2009-01-01

    The majority of extrasolar planets discovered to date have significantly eccentric orbits, some if not all of which may have been produced through planetary migration. During this process, any planets interior to such an orbit would therefore have been susceptible to resonance capture, and hence may exhibit measurable orbital period variations. Here we summarize the results of our investigation into the possibility of detecting low-mass planets which have been captured into the strong 2:1 resonance. Using analytical expressions together with simulated data we showed that it is possible to identify the existence of a low-mass companion in the internal 2:1 resonance by estimating the time-dependant orbital period for piecewise sections of radial velocity data. This works as long as the amplitude of modulation of the orbital period is greater than its uncertainty, which in practice means that the system should not be too close to exact resonance. Here we provide simple expressions for the libration period and th...

  15. Coupling of Acoustic Vibrations to Plasmon Resonances in Metal Nanoparticles

    Ahmed, Aftab; Pelton, Matthew; Guest, Jeffrey

    Measurements of acoustic vibrations in nanoparticles provide a unique opportunity to study mechanical phenomena at nanometer length scales and picosecond time scales. Phonon vibrations of plasmonic nanoparticles are of particular interest, due to their large extinction efficiencies, and high sensitivity to surrounding medium. There are two mechanisms that transduce the mechanical oscillations into plasmon resonance shift: (1) changes in polarizability; and (2) changes in electron density. These mechanisms have been used to explain qualitatively the origin of the transient-absorption signals, however, a quantitative connection has not yet been made except for simple geometries. Here, we present a method to quantitatively determine the coupling between vibrational modes and plasmon modes in noble-metal nanoparticles including spheres, shells, rods and cubes. We separately determine the parts of the optical response that are due to shape changes and to changes in electron density, and we relate the optical signals to the symmetries of the vibrational and plasmon modes. These results clarify reported experimental results, and should help guide the optimization of future experiments.

  16. How can acoustic resonance reduce the average velocity in a falling body?

    V. Torres-Zúñiga

    2011-01-01

    In this article, a simple experiment is described to overcome the misconception that acoustic pressure and levitation effects are difficult to observe in school laboratories. Analysis of the free fall velocity of a toy parachute inside a vertical tube, driven by sound in a range of frequencies around the resonant condition, exhibits the resonance frequency, the node pressure zones, and the optimal conditions to obtain acoustical levitation of a light body.

  17. Acoustic resonant states on the interface between density-negative and modulus-negative metamaterial

    Lee, M. H. [Yonsei University, Wonju (Korea, Republic of); Jung, M. K.; Lee, S. H. [Yonsei University, Seoul (Korea, Republic of); Nikitov, S. A. [Russian Academy of Sciences, Moscow (Russian Federation)

    2012-01-15

    We observed resonant states on the interface between the acoustic metamaterials of negative effective mass density and negative effective modulus, which were based on membranes and side holes, respectively. All resonances excited by placing the driving pressure at different places have the same spatial pressure distribution and resonance frequency. The amplitude decayed exponentially on both sides of the interface. We present experimental results on the spatial and the spectral characteristics of the resonant states.

  18. Acoustic resonant states on the interface between density-negative and modulus-negative metamaterial

    We observed resonant states on the interface between the acoustic metamaterials of negative effective mass density and negative effective modulus, which were based on membranes and side holes, respectively. All resonances excited by placing the driving pressure at different places have the same spatial pressure distribution and resonance frequency. The amplitude decayed exponentially on both sides of the interface. We present experimental results on the spatial and the spectral characteristics of the resonant states.

  19. Cyclotron resonant scattering in gamma-ray bursts - Line strengths and signature of neutron star rotation

    Lamb, D. Q.; Wang, J. C. L.; Wasserman, I.

    1992-01-01

    We explain the relative line strengths in gamma-ray bursts in terms of cyclotron resonant scattering. We describe the line signature of neutron star rotation and discuss the possibility that variations seen in the strengths and widths of the lines in GB780325 and GB870303 are due to rotation.

  20. Experimental study on flow-induced acoustic resonance in square closed side branch

    Flow-induced acoustic resonance is a phenomenon caused by the interaction of flow and acoustic fields in special structure. Acoustic resonance characteristic experiments were carried out on square closed side branch. The influences of the velocity in main pipe and the length of the side branch on acoustic resonance were studied. The range of occurrence and characteristics of pressure pulsation were analyzed. Three lengths of side branches (L/d=5.6 and 7) were experimentally studied and the Reynolds number in the experiment was 2.74 X 104-2.429 X 105 while the Mach number was 0.025-0.218. The results show that the resonance frequency shows a lock-in phenomenon with the increase of velocity. As the length of the side branch increasing, the amplitude of the acoustic pressure and the resonance frequency decrease. In the considered structure, the acoustic resonance occurs when Strouhal number is 0.3-0.6 and 0.7-1.0. (authors)

  1. In-plane acoustic reflectors for reducing effective anchor loss in lateral–extensional MEMS resonators

    In this paper, novel in-plane acoustic reflectors are proposed to enhance the quality factor (Q) in lateral-mode micromachined resonators. Finite element coupled-domain simulation is used to model anchor loss and to estimate the relative change in the resonator's performance without and with the inclusion of acoustic reflectors. Several 27 and 110 MHz AlN-on-silicon resonators are fabricated and measured to validate the theoretical and simulated data. An average Q enhancement of up to 560% is reported for specific designs with reflectors over the same resonators without reflectors. The measured results trend well with the simulated data and support that the acoustic reflectors can reduce the overall anchor loss with minimum modification in the resonator design

  2. Numerical derivation of forces on particles and agglomerates in a resonant acoustic field

    Knoop, Claas; Fritsching, Udo

    2013-10-01

    Particles and agglomerates are investigated in gaseous acoustic flow fields. Acoustic fields exert forces on solid objects, which can influence the shape of the exposed bodies, even to the point of breakage of the structures. Motivated by experimentally observed breakage of agglomerates in an acoustic levitator (f = 20 kHz), a numerical study is presented that derives the acoustic forces on a complex model agglomerate from the pressure and velocity fields of a resonant standing ultrasound wave, calculated by computational fluid dynamics (CFD). It is distinguished between the drag and lift/lateral forces on the overall agglomerate and on the different primary particles of the model.

  3. Grazing incidence modeling of a metamaterial-inspired dual-resonance acoustic liner

    Beck, Benjamin S.

    2014-03-01

    To reduce the noise emitted by commercial aircraft turbofan engines, the inlet and aft nacelle ducts are lined with acoustic absorbing structures called acoustic liners. Traditionally, these structures consist of a perforated facesheet bonded on top of a honeycomb core. These traditional perforate over honeycomb core (POHC) liners create an absorption spectra where the maximum absorption occurs at a frequency that is dictated by the depth of the honeycomb core; which acts as a quarter-wave resonator. Recent advances in turbofan engine design have increased the need for thin acoustic liners that are effective at low frequencies. One design that has been developed uses an acoustic metamaterial architecture to improve the low frequency absorption. Specifically, the liner consists of an array of Helmholtz resonators separated by quarter-wave volumes to create a dual-resonance acoustic liner. While previous work investigated the acoustic behavior under normal incidence, this paper outlines the modeling and predicted transmission loss and absorption of a dual-resonance acoustic metamaterial when subjected to grazing incidence sound.

  4. Acoustic Resonance Spectroscopy (ARS) Munition Classification System enhancements. Final report

    Vela, O.A.; Huggard, J.C.

    1997-09-18

    Acoustic Resonance Spectroscopy (ARS) is a non-destructive evaluation technology developed at the Los Alamos National Laboratory (LANL). This technology has resulted in three generations of instrumentation, funded by the Defense Special Weapons Agency (DSWA), specifically designed for field identification of chemical weapon (CW) munitions. Each generation of ARS instrumentation was developed with a specific user in mind. The ARS1OO was built for use by the U.N. Inspection Teams going into Iraq immediately after the Persian Gulf War. The ARS200 was built for use in the US-Russia Bilateral Chemical Weapons Treaty (the primary users for this system are the US Onsite Inspection Agency (OSIA) and their Russian counterparts). The ARS300 was built with the requirements of the Organization for the Prohibition of Chemical Weapons (OPCW) in mind. Each successive system is an improved version of the previous system based on learning the weaknesses of each and, coincidentally, on the fact that more time was available to do a requirements analysis and the necessary engineering development. The ARS300 is at a level of development that warrants transferring the technology to a commercial vendor. Since LANL will supply the computer software to the selected vendor, it is possible for LANL to continue to improve the decision algorithms, add features where necessary, and adjust the user interface before the final transfer occurs. This paper describes the current system, ARS system enhancements, and software enhancements. Appendices contain the Operations Manual (software Version 3.01), and two earlier reports on enhancements.

  5. Random matrix theory and acoustic resonances in plates with an approximate symmetry

    Andersen, Anders Peter; Ellegaard, C.; Jackson, A.D.;

    2001-01-01

    the widths for acoustic resonances in thin aluminum plates, cut in the shape of the so-called three-leaf clover. Due to the mirror symmetry through the middle plane of the plate, each resonance of the plate belongs to one of two mode classes and we show how to separate the modes into these two classes...

  6. Study of the onset of the acoustic streaming in parallel plate resonators with pulse ultrasound.

    Castro, Angelica; Hoyos, Mauricio

    2016-03-01

    In a previous study, we introduced pulse mode ultrasound as a new method for reducing and controlling the acoustic streaming in parallel plate resonators (Hoyos and Castro, 2013). Here, by modifying other parameters such as the resonator geometry and the particle size, we have found a threshold for particle manipulation with ultrasonic standing waves in confined resonators without the influence of the acoustic streaming. We demonstrate that pulse mode ultrasound open the possibility of manipulating particles smaller than 1 μm size. PMID:26705604

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

    Zhixin Zhang

    2015-09-01

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

  8. Intrinsically tunable bulk acoustic wave resonators based on sol-gel grown PMN-PT films

    Vorobiev, A.; Spreitzer, M.; Veber, A.; Suvorov, D.; Gevorgian, S.

    2014-08-01

    Intrinsically tunable bulk acoustic wave resonators, based on sol-gel 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PMN-PT) thin films, with high effective electromechanical coupling coefficient of 13% and tunability of the series resonance frequency up to 4.0% are fabricated and characterized. The enhanced electroacoustic properties of the PMN-PT resonators are attributed to the mechanism of polarization rotation occurring in the region of the morphotropic phase boundary. Electroacoustic performance of the PMN-PT resonators is analyzed using the theory of dc field-induced piezoelectric effect in ferroelectrics. Extrinsic acoustic loss in the PMN-PT resonators is analyzed using the model of the wave scattering at reflections from rough interfaces. Mechanical Q-factor of the resonators is up to 70 at 4.1 GHz and limited mainly by losses in the PMN-PT film.

  9. Resonant signatures of heavy scalar fields in the cosmic microwave background

    We investigate the possibility that a heavy scalar field, whose mass exceeds the Hubble scale during inflation, could leave non-negligible signatures in the Cosmic Microwave Background (CMB) temperature anisotropy power spectrum through the parametric resonance between its background oscillations and the inflaton fluctuations. By assuming the heavy scalar field couples with the inflaton derivatively, we show that the resonance can be efficient without spoiling the slow-roll inflation. The primordial power spectrum modulated by the resonance has a sharp peak at a specific scale and could be an origin of the anomalies observed in the angular power spectrum of the CMB. In some values of parameters, the modulated spectrum can fit the observed data better than the simple power-law power spectrum, though the resultant improvement of the fit is not large enough and hence other observations such as non-Gaussianity are necessary to confirm that the CMB anomalies are originated from the resonant effect of the heavy scalar field. The resonant signatures can provide an opportunity to observe heavy degrees of freedom during inflation and improve our understanding of physics behind inflation

  10. Giant suppression of shot noise as signature of coherent transport in double barrier resonant diodes

    Aleshkin, V. Ya.; Reggiani, L.; Alkeev, N. V.; Lyubchenko, V.E.; Ironside, C. N.; Figueiredo, J.M.L.; Stanley, C.R.

    2004-01-01

    Shot noise suppression in double barrier resonant tunnelling diodes with a Fano factor well below the value of 0.5 is theoretically predicted. This giant suppression is found to be a signature of the coherent transport regime and can occur near zero temperature as a consequence of the Pauli principle or above about 77 K as a consequence of long range Coulomb interaction. These predictions are validated by experimental data.

  11. A numerically efficient damping model for acoustic resonances in microfluidic cavities

    Hahn, P., E-mail: hahnp@ethz.ch; Dual, J. [Institute of Mechanical Systems (IMES), Department of Mechanical and Process Engineering, ETH Zurich, Tannenstrasse 3, CH-8092 Zurich (Switzerland)

    2015-06-15

    Bulk acoustic wave devices are typically operated in a resonant state to achieve enhanced acoustic amplitudes and high acoustofluidic forces for the manipulation of microparticles. Among other loss mechanisms related to the structural parts of acoustofluidic devices, damping in the fluidic cavity is a crucial factor that limits the attainable acoustic amplitudes. In the analytical part of this study, we quantify all relevant loss mechanisms related to the fluid inside acoustofluidic micro-devices. Subsequently, a numerical analysis of the time-harmonic visco-acoustic and thermo-visco-acoustic equations is carried out to verify the analytical results for 2D and 3D examples. The damping results are fitted into the framework of classical linear acoustics to set up a numerically efficient device model. For this purpose, all damping effects are combined into an acoustofluidic loss factor. Since some components of the acoustofluidic loss factor depend on the acoustic mode shape in the fluid cavity, we propose a two-step simulation procedure. In the first step, the loss factors are deduced from the simulated mode shape. Subsequently, a second simulation is invoked, taking all losses into account. Owing to its computational efficiency, the presented numerical device model is of great relevance for the simulation of acoustofluidic particle manipulation by means of acoustic radiation forces or acoustic streaming. For the first time, accurate 3D simulations of realistic micro-devices for the quantitative prediction of pressure amplitudes and the related acoustofluidic forces become feasible.

  12. A numerically efficient damping model for acoustic resonances in microfluidic cavities

    Bulk acoustic wave devices are typically operated in a resonant state to achieve enhanced acoustic amplitudes and high acoustofluidic forces for the manipulation of microparticles. Among other loss mechanisms related to the structural parts of acoustofluidic devices, damping in the fluidic cavity is a crucial factor that limits the attainable acoustic amplitudes. In the analytical part of this study, we quantify all relevant loss mechanisms related to the fluid inside acoustofluidic micro-devices. Subsequently, a numerical analysis of the time-harmonic visco-acoustic and thermo-visco-acoustic equations is carried out to verify the analytical results for 2D and 3D examples. The damping results are fitted into the framework of classical linear acoustics to set up a numerically efficient device model. For this purpose, all damping effects are combined into an acoustofluidic loss factor. Since some components of the acoustofluidic loss factor depend on the acoustic mode shape in the fluid cavity, we propose a two-step simulation procedure. In the first step, the loss factors are deduced from the simulated mode shape. Subsequently, a second simulation is invoked, taking all losses into account. Owing to its computational efficiency, the presented numerical device model is of great relevance for the simulation of acoustofluidic particle manipulation by means of acoustic radiation forces or acoustic streaming. For the first time, accurate 3D simulations of realistic micro-devices for the quantitative prediction of pressure amplitudes and the related acoustofluidic forces become feasible

  13. Fabrication of Capacitive Acoustic Resonators Combining 3D Printing and 2D Inkjet Printing Techniques

    Rubaiyet Iftekharul Haque; Erick Ogam; Christophe Loussert; Patrick Benaben; Xavier Boddaert

    2015-01-01

    A capacitive acoustic resonator developed by combining three-dimensional (3D) printing and two-dimensional (2D) printed electronics technique is described. During this work, a patterned bottom structure with rigid backplate and cavity is fabricated directly by a 3D printing method, and then a direct write inkjet printing technique has been employed to print a silver conductive layer. A novel approach has been used to fabricate a diaphragm for the acoustic sensor as well, where the conductive ...

  14. Effects of relevant parameters on the bandgaps of acoustic metamaterials with multi-resonators

    Zhou, Xiaoqin; Wang, Jun; Wang, Rongqi; Lin, Jieqiong

    2016-04-01

    Locally resonant acoustic metamaterials with multi-resonators are generally regarded as a fine trend for managing the bandgaps, the different effects of relevant structural parameters on the bandgaps, which will be numerically investigated in this paper. A two-step homogenization method is extended to achieve the effective mass of multi-resonators metamaterial in the lattice system. As comparison, the dispersive wave propagation in lattice system and continuum model is studied. Then, the different effects of relevant parameters on the center frequencies and bandwidth of bandgaps are perfectly revealed, and the steady-state responses in the continuum models with purposed relevant parameters are additionally clarified. The related results can well confirm that the bandgaps exist around the undamped natural frequencies of internal resonators, and also their bandwidth can be efficiently controlled with the ensured center frequencies. Moreover, the design of purposed multi-resonators acoustic metamaterial in vibration control is presented and discussed by an example.

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

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

    2016-02-01

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

  16. Optimization of the Acoustic Pressure Distribution in a Resonant Photoacoustic Cell

    陈柏; 陈兰荣; 范薇; 林尊琪

    2001-01-01

    The size of a cylindrical photoacoustic cell with suitable size was selected so that the resonant frequency of the first radial mode was equal to that of a longitudinal higher mode. By maintaining two thin coaxial tubes at each end, a enhanced photoacoustic cell was constructed with two tubes of 1/2 and 1/4 of the wavelength. In this enhanced photoacoustie cell, both the first radial resonance and the higher longitudinal resonance were excited adequately. Coupling of two acoustic modes makes the acoustic energy concentrating in the middle of the cell. The surface loss was decreased, the acoustic quality factor and pressure amplitude increased obviously as compared with conventional cylindrical cell.

  17. Wide-band underwater acoustic absorption based on locally resonant unit and interpenetrating network structure

    The interpenetrating network structure provides an interesting avenue to novel materials. Locally resonant phononic crystal (LRPC) exhibits excellent sound attenuation performance based on the periodical arrangement of sound wave scatters. Combining the LRPC concept and interpenetrating network glassy structure, this paper has developed a new material which can achieve a wide band underwater strong acoustic absorption. Underwater absorption coefficients of different samples were measured by the pulse tube. Measurement results show that the new material possesses excellent underwater acoustic effects in a wide frequency range. Moreover, in order to investigate impacts of locally resonant units, some defects are introduced into the sample. The experimental result and the theoretical calculation both show that locally resonant units being connected to a network structure play an important role in achieving a wide band strong acoustic absorption. (condensed matter: structure, thermal and mechanical properties)

  18. Extremely high Q-factor mechanical modes in quartz bulk acoustic wave resonators at millikelvin temperature

    Goryachev, M.; Creedon, D. L.; Ivanov, E. N.; Tobar, M. E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia); Galliou, S.; Bourquin, R. [Department of Time and Frequency, FEMTO-ST Institute, ENSMM, 26 Chemin de l' Épitaphe, 25000, Besançon (France)

    2014-12-04

    We demonstrate that Bulk Acoustic Wave (BAW) quartz resonator cooled down to millikelvin temperatures are excellent building blocks for hybrid quantum systems with extremely long coherence times. Two overtones of the longitudinal mode at frequencies of 15.6 and 65.4 MHz demonstrate a maximum f.Q product of 7.8×10{sup 16} Hz. With this result, the Q-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained in other mechanical systems. Tested quartz resonators possess the ultra low acoustic losses crucial for electromagnetic cooling to the phonon ground state.

  19. Multi-band and broadband acoustic metamaterial with resonant structures

    We design an acoustic metamaterial (AM) with multi-band of negative modulus composed of different sized split hollow spheres (SHSs). From acoustic transmitted experiment, the AM exhibits simultaneously negative modulus at frequencies 914, 1298 and 1514 Hz. Based on the multi-band designed concept, broadband AM is fabricated by arraying gradually sized SHS. The transmission results indicate that this medium can achieve negative modulus at the frequency range from 900 to 1500 Hz. This kind of broadband AM is very convenient to couple with other structures to gain the double-negative AM.

  20. Enlargement of locally resonant sonic band gap by using composite plate-type acoustic metamaterial

    We numerically investigate the propagation characteristics of Lamb waves in composite plate-type acoustic metamaterial constituted of one-side cylindrical stubs deposited on a two-dimensional binary locally resonant phononic plate. Numerical results show that, with the introduction of composite plate-type acoustic metamaterial, locally resonant band gap shifts to lower frequency, and a significant enlargement of the relative bandwidth by a factor of 3 can be obtained, compared to one-side locally resonant stubbed plates. We show that the band gap enlargement is attributed to the coupling between the local resonant Lamb modes of two-dimensional phononic plate and the resonant modes of the stubs. - Highlights: • An original composite plate-type locally resonant acoustic metamaterial is proposed. • A significant enlargement of the relative bandwidth by a factor of 3 can be obtained. • The band gap enlargement is attributed to the locally resonant complex effect. • The band gap is significantly dependent upon the geometrical parameters

  1. Analysis of underwater decoupling properties of a locally resonant acoustic metamaterial coating

    Ling-Zhi, Huang; Yong, Xiao; Ji-Hong, Wen; Hai-Bin, Yang; Xi-Sen, Wen

    2016-02-01

    This paper presents a semi-analytical solution for the vibration and sound radiation of a semi-infinite plate covered by a decoupling layer consisting of locally resonant acoustic metamaterial. Formulations are derived based on a combination use of effective medium theory and the theory of elasticity for the decoupling material. Theoretical results show good agreements between the method developed in this paper and the conventional finite element method (FEM), but the method of this paper is more efficient than FEM. Numerical results also show that system with acoustic metamaterial decoupling layer exhibits significant noise reduction performance at the local resonance frequency of the acoustic metamaterial, and such performance can be ascribed to the vibration suppression of the base plate. It is demonstrated that the effective density of acoustic metamaterial decoupling layer has a great influence on the mechanical impedance of the system. Furthermore, the resonance frequency of locally resonant structure can be effectively predicted by a simple model, and it can be significantly affected by the material properties of the locally resonant structure. Project supported by the National Natural Science Foundation of China (Grant Nos. 51305448 and 51275519).

  2. Resonance Effects of Bilayered Piezoelectric Films Used for Bulk Acoustic Wave Sensors

    ZHANG Hui; ZHANG Shu-Yi; FAN Li

    2011-01-01

    The resonance vibrations of acoustic sensors with two layers of (1120) textured hexagonal piezoelectric films are studied.When the acoustic and electric fields satisfy a special match condition,i.e.the phase variation of thickness shear mode (TSM) at each film equals π,both piezoelectric layers with opposite polarization directions reduce the first TSM and generate the second TSM with higher frequency and a higher quality factor.The excited second TSM can increase the product of the operating frequency and the quality factor,which is useful for improving the mass sensitivity and resolution of acoustic sensors.Additionally,both of the piezoelectric films have larger thickness and decrease the risk of mechanical damage in device production processes.Thin film bulk acoustic sensors have attracted great attention due to their small sizes,low power consumption and high sensitivity,etc.[1] The thickness shear mode (TSM) is more suitable for liquid sensing applications since much less acoustic energy is transferred into the liquid medium than that of longitudinal acoustic waves,due to the fact that ideal liquids cannot support propagations of shear waves.By using a TSM with a high resonance frequency,sensorsbased on thin film bulk acoustic resonator structures can be fabricated by the fixing of a sensitive coating on the surface of the device.[2] The binding events at the sensitive coating can cause a shift of the resonance frequency.[3]%The resonance vibrations of acoustic sensors with two layers of (1120) textured hexagonal piezoelectric films are studied. When the acoustic and electric fields satisfy a special match condition, I.e. The phase variation of thickness shear mode (TSM) at each film equals it, both piezoelectric layers with opposite polarization directions reduce the first TSM and generate the second TSM with higher frequency and a higher quality factor. The excited second TSM can increase the product of the operating frequency and the quality factor, which

  3. Dispersion and damping of multi-quantum well polaritons from resonant Brillouin scattering by folded acoustic modes

    Jusserand, B.; Fainstein, A.; Ferreira, R.; Majrab, S.; Lemaitre, A.

    2011-01-01

    We report on confined exciton resonances of acoustic and folded acoustic phonon light scattering in a GaAs/AlAs multi-quantum-well. Significant variations of the line shifts and widths are observed across the resonance and quantitatively reproduced in terms of the polariton dispersion. This high resolution Brillouin study brings new unexpectedly detailed informations on the polariton dynamics in confined systems.

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

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

  5. Opto-acoustic phenomena in whispering gallery mode resonators

    Lin, Guoping; Chembo, Yanne K.

    2016-01-01

    Optical whispering gallery mode resonators are important platforms to enhance and study various nonlinear frequency conversion processes. Stimulated Brillouin scattering is one of the strongest nonlinear effects, and can be successfully investigated using these platforms. In this article, we study the phenomenon of stimulated Brillouin scattering using a crystalline disk resonator. A fast scanning ringdown spectroscopy technique is used to characterize the optical modes featuring quality factors of the order of one billion at telecom wavelengths. The mW scale threshold power in a centimeter disk resonator is observed and found to be strongly dependent on the gap between the resonator and the prism coupler.

  6. Signature of the $\\Lambda(1405)$ resonance in neutron spectra from the $K^-+d$ reaction

    Révai, János

    2012-01-01

    Neutron spectra from the reaction $K^-+d\\rightarrow \\pi+\\Sigma+n$ were calculated in the energy range $E^{cm}_{K^-}= 0-50\\ MeV$ using coupled channel Faddeev equations for the description of the $\\bar KNN-\\pi\\Sigma N$ three-body system. The aim was to trace the signature of the $\\Lambda(1405)$ resonance in the spectra. We found, that while in the direct spectra kinematic effects mask completely the peak corresponding to the resonance, the deviation spectrum method \\cite{AY} is able to eliminate kinematics and produce clear evidence of the resonance. The dependence of the obtained spectra on the incident kaon energy is discussed.

  7. Surface resonant states in acoustic and elastic metamaterials

    Ambati, Muralidhar; Wu, Dongmin; Zhang, Xiang

    2007-03-01

    We discuss a new type of surface acoustic wave at an interface between two media, one of which is a metamaterial. In contrast to the familiar case where the surface acoustic waves exist at solid-fluid and solid-solid interfaces, these unique waves exist because of the negative material responses in metamaterials. We explore the existence of a surface wave a) at the interface of a fluid and an acoustic metamaterial modeled as a fluid and b) at the interface of a solid and an elastic metamaterial modeled as a solid. The latter case is for shear waves with horizontal polarization (SH). In each of these two cases, first, we discuss the necessary and sufficient conditions on the material properties of metamaterials for the existence of surface modes. Second, we offer the microscopic picture of these surface modes in terms of particle trajectories at the interfaces. Next, we examine the unique characteristics of these surface states; as a result, we propose and numerically demonstrate an acoustic superlens for sub-diffraction limited imaging. Finally, we provide a design for metamaterials that can lead to the surface states and make a significant impact in ultrasonic imaging.

  8. Tunable band gaps in acoustic metamaterials with periodic arrays of resonant shunted piezos

    Chen Sheng-Bing; Wen Ji-Hong; Wang Gang; Wen Xi-Sen

    2013-01-01

    Periodic arrays of resonant shunted piezoelectric patches are employed to control the wave propagation in a twodimensional (2D) acoustic metamaterial.The performance is characterized by the finite element method.More importantly,we propose an approach to solving the conventional issue of the nonlinear eigenvalue problem,and give a convenient solution to the dispersion properties of 2D metamaterials with periodic arrays of resonant shunts in this article.Based on this modeling method,the dispersion relations of a 2D metamaterial with periodic arrays of resonant shunted piezos are calculated.The results show that the internal resonances of the shunting system split the dispersion curves,thereby forming a locally resonant band gap.However,unlike the conventional locally resonant gap,the vibrations in this locally resonant gap are unable to be completely localized in oscillators consisting of shunting inductors and piezo-patches.

  9. Tunable band gaps in acoustic metamaterials with periodic arrays of resonant shunted piezos

    Periodic arrays of resonant shunted piezoelectric patches are employed to control the wave propagation in a two-dimensional (2D) acoustic metamaterial. The performance is characterized by the finite element method. More importantly, we propose an approach to solving the conventional issue of the nonlinear eigenvalue problem, and give a convenient solution to the dispersion properties of 2D metamaterials with periodic arrays of resonant shunts in this article. Based on this modeling method, the dispersion relations of a 2D metamaterial with periodic arrays of resonant shunted piezos are calculated. The results show that the internal resonances of the shunting system split the dispersion curves, thereby forming a locally resonant band gap. However, unlike the conventional locally resonant gap, the vibrations in this locally resonant gap are unable to be completely localized in oscillators consisting of shunting inductors and piezo-patches

  10. Detection of Ionospheric Alfven Resonator Signatures Onboard C/NOFS: Implications for IRI Modeling

    Simoes, F.; Klenzing, J.; Ivanov, S.; Pfaff, R.; Rowland, D.; Bilitza, D.

    2011-01-01

    The 2008-2009 long-lasting solar minimum activity has been the one of its kind since the dawn of space age, offering exceptional conditions for investigating space weather in the near-Earth environment. First ever detection of Ionospheric Alfven Resonator (IAR) signatures in orbit offers new means for investigating ionospheric electrodynamics, namely MHD (MagnetoHydroDynamics) wave propagation, aeronomy processes, ionospheric dynamics, and Sun-Earth connection mechanisms at a local scale. Local and global plasma density heterogeneities in the ionosphere and magnetosphere allow for formation of waveguides and resonators where magnetosonic and shear Alfven waves propagate. The ionospheric magnetosonic waveguide results from complete magnetosonic wave reflection about the ionospheric F-region peak, where the Alfven index of refraction presents a maximum. MHD waves can also be partially trapped in the vertical direction between the lower boundary of the ionosphere and the magnetosphere, a resonance mechanism known as IAR. In this work we present C/NOFS (Communications/Navigation Outage Forecasting System) Extremely Low Frequency (ELF) electric field measurements related to IAR signatures, discuss the resonance and wave propagation mechanisms in the ionosphere, and address the electromagnetic inverse problem from which electron/ion distributions can be derived. These peculiar IAR electric field measurements provide new, complementary methodologies for inferring ionospheric electron and ion density profiles, and also contribute for the investigation of ionosphere dynamics and space weather monitoring. Specifically, IAR spectral signatures measured by C/NOFS contribute for improving the International Reference Ionosphere (IRI) model, namely electron density and ion composition.

  11. Flow-induced acoustic resonance at the mouth of one or two side branches

    Highlights: ► We investigated the effect of the geometrical and flow parameters on the flow-induced acoustic resonance. ► In the case of a single branch, the dimensionless acoustic pressure amplitude at resonance increases as the cross-sectional ratio of the main and branch pipes is decreased. ► In the case of coaxial branches, the pressure amplitude shows a counter tendency to that in the case of a single branch. ► In the case of tandem branches, peak pressure and frequency change cyclically as the distance between tandem branches changes. - Abstract: In the case of flow-induced acoustic resonance with multiple side branches, the pulsation amplitude may be significantly enhanced compared to the case of a single branch. However, few studies have been presented on the effects of the distance between tandem branches or side branches on fluctuating pressure amplitude. In this study, we carried out several air flow experiments at ordinary temperatures and pressures to investigate the effect of the geometrical and flow parameters on the general acoustic resonance. In the case of a single branch, the dimensionless acoustic pressure amplitude at resonance increases as the cross-sectional ratio of the main and branch pipes is decreased. This is attributed to the acoustic radiation loss from the branch pipe to the main pipe increasing at higher values of the cross-sectional ratio. In the case of coaxial branches, the pressure amplitude shows a counter tendency to that in the case of a single branch. This is because the two branches strongly couple and form a standing wave with negligible radiation losses. In the case of tandem branches, peak pressure and frequency change cyclically as the distance between tandem branches changes.

  12. Acoustical “transparency” induced by local resonance in Bragg bandgaps

    We show that sound waves can resonantly transmit through Bragg bandgaps in an acoustical duct periodically attached with an array of Helmholtz resonators, forming within the normally forbidden band a transparency window with group velocity smaller than the normal speed of sound. The transparency occurs for the locally resonant frequency so much close to the Bragg one that both the local-resonance-induced bandgap and the Bragg one heavily overlap with each other. The phenomenon seems an acoustical analog of the well-known electromagnetically induced transparency by quantum interference. Different from the Fano-like interference explanation, we also provide a mechanism for the transparency window phenomenon which makes it possible to extend the phenomenon in general

  13. Acoustical “transparency” induced by local resonance in Bragg bandgaps

    Yu, Gaokun; Wang, Xinlong, E-mail: xlwang@nju.edu.cn [Key Laboratory of Modern Acoustics and Institute of Acoustics, Nanjing University, Nanjing 210093 (China)

    2014-01-28

    We show that sound waves can resonantly transmit through Bragg bandgaps in an acoustical duct periodically attached with an array of Helmholtz resonators, forming within the normally forbidden band a transparency window with group velocity smaller than the normal speed of sound. The transparency occurs for the locally resonant frequency so much close to the Bragg one that both the local-resonance-induced bandgap and the Bragg one heavily overlap with each other. The phenomenon seems an acoustical analog of the well-known electromagnetically induced transparency by quantum interference. Different from the Fano-like interference explanation, we also provide a mechanism for the transparency window phenomenon which makes it possible to extend the phenomenon in general.

  14. Kiwi fruit (Actinidia chinensis) quality determination based on surface acoustic wave resonator combined with electronic nose

    Wei, Liu; Guohua, Hui

    2015-01-01

    In this study, electronic nose (EN) combined with a 433 MHz surface acoustic wave resonator (SAWR) was used to determine Kiwi fruit quality under 12-day storage. EN responses to Kiwi samples were measured and analyzed by principal component analysis (PCA) and stochastic resonance (SR) methods. SAWR frequency eigen values were also measured to predict freshness. Kiwi fruit sample's weight loss index and human sensory evaluation were examined to characteristic its quality and freshness. Kiwi fr...

  15. DEVELOPMENT OF ACOUSTIC MODELS FOR HIGH FREQUENCY RESONATORS FOR TURBOCHARGED IC-ENGINES

    Wang, Zheng

    2012-01-01

    Automotive turbo compressors generate high frequency noise in the air intake system. This sound generation is of importance for the perceived sound quality of luxury cars and may need to be controlled by the use of silencers. The silencers usually contain resonators with slits, perforates and cavities. The purpose of the work reported is to develop acoustic models for these resonators where relevant effects such as the effect of realistic mean flow on losses and possibly 3D effects are consid...

  16. Demonstration of slow sound propagation and acoustic transparency with a series of detuned resonators

    Santillan, Arturo Orozco; Bozhevolnyi, Sergey I.

    2014-01-01

    We present experimental results demonstrating the phenomenon of acoustic transparency with a significant slowdown of sound propagation realized with a series of paired detuned acoustic resonators (DAR) side-attached to a waveguide. The phenomenon mimics the electromagnetically induced transparency...... of more than 20 dB on both sides of the transparency window, and we quantify directly (using a pulse propagation) the acoustic slowdown effect, resulting in the sound group velocity of 9.8 m/s (i.e. in the group refractive index of 35). We find very similar values of the group refractive index by...... using measurements of the phase of the transmitted wave. It is also shown that a direct coupling exists between the DAR in each pair, which cannot be explained by the interference of waves radiated from those resonators. This detrimental coupling becomes noticeable for small values of detuning and also...

  17. Acoustic resonances in two dimensional radial sonic crystals shells

    Torrent, Daniel; Sánchez-Dehesa, José

    2010-01-01

    Radial sonic crystals (RSC) are fluidlike structures infinitely periodic along the radial direction. They have been recently introduced and are only possible thanks to the anisotropy of specially designed acoustic metamaterials [see Phys. Rev. Lett. {\\bf 103} 064301 (2009)]. We present here a comprehensive analysis of two-dimensional RSC shells, which consist of a cavity defect centered at the origin of the crystal and a finite thickness crystal shell surrounded by a fluidlike background. We ...

  18. Subterahertz acoustical pumping of electronic charge in a resonant tunneling device.

    Young, E S K; Akimov, A V; Henini, M; Eaves, L; Kent, A J

    2012-06-01

    We demonstrate that controlled subnanosecond bursts of electronic charge can be transferred through a resonant tunneling diode by successive picosecond acoustic pulses. The effect exploits the nonlinear current-voltage characteristics of the device and its asymmetric response to the compressive and tensile components of the strain pulse. This acoustoelectronic pump opens new possibilities for the control of quantum phenomena in nanostructures. PMID:23003634

  19. Detection of acoustic resonance effects on the ground and in the ionosphere at the total eclipses

    Complete text of publication follows. The ground - lower atmosphere - thermosphere (ionosphere) coupling effects through acoustic resonance have been observed, for example, for the Mt. Pinatubo eruption in 1991 (Kanamori and Mori, 1992) and the great 2004 Sumatra earthquake (Iyemori et al., 2005). In the Mt. Pinatubo case, it was assumed that the acoustic wave (i.e., pressure variation) caused a very low frequency oscillation of the ground observed worldwide. However, a volcanic eruption or earthquake can also cause the ground oscillation directly. The ground oscillation may cause atmospheric oscillations but with a complicated causality. In the case of typhoons when the resonance effects have been detected, the ocean waves also make the situation complicated. When a total eclipse occurs, the rapid pressure variations, caused by the rapid decrease of temperature may also generate the acoustic resonance, however, in this case, the situation is expected to be simpler than for volcanic eruptions. This situation provides better conditions for quantitative modeling of the acoustic resonance effects. On July 22, 2009, a total eclipse will be observed along a band from China, Iwo Island, and through the Tokara Islands, south of Japan. We plan to make barometric, geomagnetic, GPS-TEC and HF Doppler observations at several points along the eclipse path. In this paper, we show some results of analysis of the data obtained from the total eclipses in the past and preliminary results of the observations from the July 22, 2009 event.

  20. The acoustic signatures of ground acceleration, gas expansion, and spall fallback in experimental volcanic explosions

    Bowman, Daniel C.; Taddeucci, Jacopo; Kim, Keehoon; Anderson, Jacob F.; Lees, Jonathan M.; Graettinger, Alison H.; Sonder, Ingo; Valentine, Greg A.

    2014-03-01

    Infrasound and high-speed imaging during a series of field-scale buried explosions suggest new details about the generation and radiation patterns of acoustic waves from volcanic eruptions. We recorded infrasound and high-speed video from a series of subsurface explosions with differing burial depths and charge sizes. Joint observations and modeling allow the extraction of acoustic energy related to the magnitude of initial ground deformation, the contribution of gas breakout, and the timing of the fallback of displaced material. The existence and relative acoustic amplitudes of these three phases depended on the size and depth of the explosion. The results motivate a conceptual model that relates successive contributions from ground acceleration, gas breakout, and spall fallback to the acoustic amplitude and waveform characteristics of buried explosions. We place the literature on infrasound signals at Santiaguito Volcano, Guatemala, and Sakurajima and Suwonosejima Volcanoes, Japan, in the context of this model.

  1. Coherent Control of Ultra-High Frequency Acoustic Resonances in Photonic Crystal Fibers

    Wiederhecker, G S; Fragnito, H L; Russell, P St J

    2007-01-01

    UHF (ultra-high frequency) acoustic resonances (~2 GHz) trapped within the glass core (1 micron diameter) of a photonic crystal fibre are excited electrostrictively using laser pulses of duration 100 ps and energy 500 pJ. Using precisely timed sequences of such driving pulses, we achieve coherent control of the acoustic resonances by constructive or destructive interference, demonstrating both enhancement and suppression of the vibrations. A sequence of resonantly-timed pulses (limited to 25 by the capacity of the erbium-doped fibre amplifier used) provides a 100-fold increase in the amplitude of the vibrational mode. The results are explained and interpreted using a semi-analytical theory, and supported by precise numerical simulations of the complex light-matter interaction.

  2. Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer

    Chen, Guohao; Zhao, Xinru; Wang, Xiaozhi; Jin, Hao; Li, Shijian; Dong, Shurong; Flewitt, A. J.; Milne, W. I.; Luo, J. K.

    2015-03-01

    The film bulk acoustic resonator (FBAR) is a widely-used MEMS device which can be used as a filter, or as a gravimetric sensor for biochemical or physical sensing. Current device architectures require the use of an acoustic mirror or a freestanding membrane and are fabricated as discrete components. A new architecture is demonstrated which permits fabrication and integration of FBARs on arbitrary substrates. Wave confinement is achieved by fabricating the resonator on a polyimide support layer. Results show when the polymer thickness is greater than a critical value, d, the FBARs have similar performance to devices using alternative architectures. For ZnO FBARs operating at 1.3-2.2 GHz, d is ~9 μm, and the devices have a Q-factor of 470, comparable to 493 for the membrane architecture devices. The polymer support makes the resonators insensitive to the underlying substrate. Yields over 95% have been achieved on roughened silicon, copper and glass.

  3. Sound Transmission Loss Through a Corrugated-Core Sandwich Panel with Integrated Acoustic Resonators

    Schiller, Noah H.; Allen, Albert R.; Zalewski, Bart F; Beck, Benjamin S.

    2014-01-01

    The goal of this study is to better understand the effect of structurally integrated resonators on the transmission loss of a sandwich panel. The sandwich panel has facesheets over a corrugated core, which creates long aligned chambers that run parallel to the facesheets. When ports are introduced through the facesheet, the long chambers within the core can be used as low-frequency acoustic resonators. By integrating the resonators within the structure they contribute to the static load bearing capability of the panel while also attenuating noise. An analytical model of a panel with embedded resonators is derived and compared with numerical simulations. Predictions show that acoustic resonators can significantly improve the transmission loss of the sandwich panel around the natural frequency of the resonators. In one configuration with 0.813 m long internal chambers, the diffuse field transmission loss is improved by more than 22 dB around 104 Hz. The benefit is achieved with no added mass or volume relative to the baseline structure. The embedded resonators are effective because they radiate sound out-of-phase with the structure. This results in destructive interference, which leads to less transmitted sound power.

  4. Electro-thermo-mechanical model for bulk acoustic wave resonators.

    Rocas, Eduard; Collado, Carlos; Mateu, Jordi; Orloff, Nathan D; Aigner, Robert; Booth, James C

    2013-11-01

    We present the electro-thermo-mechanical constitutive relations, expanded up to the third order, for a BAW resonator. The relations obtained are implemented into a circuit model, which is validated with extensive linear and nonlinear measurements. The mathematical analysis, along with the modeling, allows us to identify the dominant terms, which are the material temperature derivatives and two intrinsic nonlinear terms, and explain, for the first time, all observable effects in a BAW resonator by use of a unified physical description. Moreover, the terms that are responsible for the second-harmonic generation and the frequency shift with dc voltage are shown to be the same. PMID:24158294

  5. Selective magnetic resonance imaging of magnetic nanoparticles by Acoustically Induced Rotary Saturation (AIRS)

    Zhu, Bo; Witzel, Thomas; Jiang, Shan; Huang, Susie Y.; Rosen, Bruce R.; Wald, Lawrence L.

    2016-01-01

    Purpose We introduce a new method to selectively detect iron oxide contrast agents using an acoustic wave to perturb the spin-locked water signal in the vicinity of the magnetic particles. The acoustic drive can be externally modulated to turn the effect on and off, allowing sensitive and quantitative statistical comparison and removal of confounding image background variations. Methods We demonstrate the effect in spin-locking experiments using piezoelectric actuators to generate vibrational displacements of iron oxide samples. We observe a resonant behavior of the signal changes with respect to the acoustic frequency where iron oxide is present. We characterize the effect as a function of actuator displacement and contrast agent concentration. Results The resonant effect allows us to generate block-design “modulation response maps” indicating the contrast agent’s location, as well as positive contrast images with suppressed background signal. We show the AIRS effect stays approximately constant across acoustic frequency, and behaves monotonically over actuator displacement and contrast agent concentration. Conclusion AIRS is a promising method capable of using acoustic vibrations to modulate the contrast from iron oxide nanoparticles and thus perform selective detection of the contrast agents, potentially enabling more accurate visualization of contrast agents in clinical and research settings. PMID:25537578

  6. Raman albedo and deep-UV resonance Raman signatures of explosives

    Yellampalle, Balakishore; Lemoff, Brian E.

    2013-05-01

    Deep-ultraviolet resonance Raman spectroscopy (DUVRRS) is a promising approach to stand-off detection of explosive traces due to large Raman cross-section and background free signatures. In order to design an effective sensor, one must be able to estimate the signal level of the DUVRRS signature for solid-phase explosive residues. The conventional approach to signal estimation uses scattering cross-sections and molar absorptivity, measured on solutions of explosives dissolved in an optically-transparent solvent. Only recently have researchers started to measure solid-state cross-sections. For most solid-phase explosives and explosive mixtures, neither the DUV Raman scattering cross sections nor the optical absorption coefficient are known, and they are very difficult to separately measure. Therefore, for a typical solid explosive mixture, it is difficult to accurately estimate Raman signal strength using conventional approaches. To address this issue, we have developed a technique to measure the Raman scattering strength of optically-thick (opaque) materials, or "Raman Albedo", defined as the total power of Raman-scattered light per unit frequency per unit solid angle divided by the incident power of the excitation source. We have measured Raman Albedo signatures for a wide range of solid explosives at four different DUV excitation wavelengths. These results will be presented, and we will describe the use of Raman Albedo measurements in the design and current construction of a novel stand-off explosive sensor, based on dual-excitation-wavelength DUVRRS.

  7. Numerical and experimental investigation of a low-frequency measurement technique: differential acoustic resonance spectroscopy

    Yin, Hanjun; Zhao, Jianguo; Tang, Genyang; Ma, Xiaoyi; Wang, Shangxu

    2016-06-01

    Differential acoustic resonance spectroscopy (DARS) has been developed to determine the elastic properties of saturated rocks within the kHz frequency range. This laboratory technique is based on considerations from perturbation theory, wherein the resonance frequencies of the resonant cavity with and without a perturbation sample are used to estimate the acoustic properties of the test sample. In order to better understand the operating mechanism of DARS and therefore optimize the procedure, it is important to develop an accurate and efficient numerical model. Accordingly, this study presents a new multiphysics model by coupling together considerations from acoustics, solid mechanics, and electrostatics. The numerical results reveal that the newly developed model can successfully simulate the acoustic pressure field at different resonance modes, and that it can accurately reflect the measurement process. Based on the understanding of the DARS system afforded by the numerical simulation, we refine the system configuration by utilizing cavities of different lengths and appropriate radii to broaden the frequency bandwidth and ensure testing accuracy. Four synthetic samples are measured to test the performance of the optimized DARS system, in conjunction with ultrasonic and static measurements. For nonporous samples, the estimated bulk moduli are shown to be independent of the different measurement methods (i.e. DARS or ultrasonic techniques). In contrast, for sealed porous samples, the differences in bulk moduli between the low- and high-frequency techniques can be clearly observed; this discrepancy is attributed to frequency dispersion. In summary, the optimized DARS system with an extended frequency range of 500–2000 Hz demonstrates considerable utility in investigating the frequency dependence of the acoustic properties of reservoir rocks.

  8. Stratospheric Observatory for Infrared Astronomy (SOFIA) Acoustical Resonance Technical Assessment Report

    Gilbert, Michael G.; Kehoe, Michael W.; Gupta, Kajal K.; Kegerise, Michael A.; Ginsberg, Jerry H.; Kolar, Ramesh

    2009-01-01

    A request was submitted on September 2, 2004 concerning the uncertainties regarding the acoustic environment within the Stratospheric Observatory for Infrared Astronomy (SOFIA) cavity, and the potential for structural damage from acoustical resonance or tones, especially if they occur at or near a structural mode. The requestor asked for an independent expert opinion on the approach taken by the SOFIA project to determine if the project's analysis, structural design and proposed approach to flight test were sound and conservative. The findings from this assessment are recorded in this document.

  9. Interaction of reed and acoustic resonator in clarinetlike systems

    Silva, Fabrice; Vergez, Christophe; Gilbert, Joël

    2008-01-01

    Sound emergence in clarinetlike instruments is investigated in terms of instability of the static regime. Various models of reed-bore coupling are considered, from the pioneering work of Wilson and Beavers ["Operating modes of the clarinet", J. Acoust. Soc. Am. 56, 653--658 (1974)] to more recent modeling including viscothermal bore losses and vena contracta at the reed inlet. The pressure threshold above which these models may oscillate as well as the frequency of oscillation at threshold are calculated. In addition to Wilson and Beavers' previous conclusions concerning the role of the reed damping in the selection of the register the instrument will play on, the influence of the reed motion induced flow is also emphasized, particularly its effect on playing frequencies, contributing to reduce discrepancies between Wilson and Beavers' experimental results and theory, despite discrepancies still remain concerning the pressure threshold. Finally, analytical approximations of the oscillating solution based on F...

  10. Air/steam flow and steam wetness dependence on acoustic resonance in safety relief valves

    Many experimental studies related to the flow-induced acoustic resonance closed side branches have been reported. However, few studies have reported on the effects of air/steam flow and steam wetness dependence on fluctuating pressure amplitude. Therefore, we investigated the effect of air/steam flow and steam wetness dependence on fluctuating pressure amplitude by conducting a high temperature and high pressure tests at the Hitachi Utility Steam Test Leading Facility (HUSTLE). The test section consisted of a main pipe and a side branch. The side branch was mounted on the long straight main pipe. Fluctuating pressures at the end face of the side branches were measured. The following two results were obtained; the first is that the air/steam flow had little effect on the fluctuating pressure amplitude normalized by dynamic pressure and frequency normalized by the resonance frequency; the second is that under the acoustic resonance (St = 0.41) and non-resonance (St = 0.55) conditions, fluctuating pressure and frequency changed little with steam wetness. The steam wetness during the boiling water reactor operation was less than 0.1%; thus, there was no effect of steam wetness on the acoustic pressure amplitude and the frequency under this operating condition. (author)

  11. Linear and Nonlinear Acoustic Measurements of Buried Landmines: Detection Schemes Near Resonance

    Sabatier, James M.

    2003-03-01

    Measurements of the acoustic impedance of an anti-personnel and anti-tank plastic, blast-hardened landmines reveal resonances in the frequency range between 100 and 1000 Hz. The top surface resonances are due to its complicated mechanical structure vibrating in air. The lowest mode results from the blast hardened design of the landmine. Typically, a portion or cavity of the landmine is designed to absorb the shock from an explosion that is intended to detonate the landmine but still allow the landmine to trigger its explosive device when a slow steady pressure is applied. The mechanical design of the blast hardened aspects results in a high Q simple harmonic oscillator resonance of the top surface. At higher frequencies the top surface behaves like thin circular plate acoustic modes. When these landmines are buried in soils, the modes are mass loaded. Resonances from measurements of the normal component of the acoustically induced soil surface particle velocity are used for detection schemes. Since the interface between the top plate and the soil responds to pressure fluctuations nonlinearly, characteristics of landmines, the soil, and the interface are rich in nonlinear physics and allow for new methods of landmine detection not previously exploited.

  12. Selective focusing through target identification and experimental acoustic signature extraction: Numerical experiments.

    Rodriguez, S; Jacob, X; Gibiat, V

    2016-05-01

    Using transducer arrays and appropriate emission delays allow to focus acoustic waves at a chosen location in a medium. The focusing spatial accuracy depends on the accurate knowledge of its acoustic properties. When those properties are unknown, methods based on the Time-Reversal principle allow accurate focusing. Still, these methods are either intrusive (an active source has to be introduced at the target location first), either blind (the target cannot be selected in the presence of several objects.) The purpose of the present work is to achieve non-invasive accurate focusing on a selected target using inaccurate acoustic properties for the investigated medium. Potential applications are for instance noninvasive surgery based on High Intensity Focused Ultrasound (HIFU). Numerical experiments are presented and demonstrate accurate focusing on a previously designated target located in an unknown heterogeneous medium. PMID:26890791

  13. R&D studies for the development of a compact transmitter able to mimic the acoustic signature of a UHE neutrino interaction

    Ardid, M; Bou-Cabo, M; Larosa, G; Mart\\inez-Mora, J A; Espinosa, V; Camarena, F; Ferri, M

    2011-01-01

    Calibration of acoustic neutrino telescopes with neutrino-like signals is an essential aspect to evaluate the feasibility of the technique and to know the efficiency of the detectors. However, it is not straightforward to have acoustic transmitters that, on one hand, are able to mimic the signature of a UHE neutrino interaction, that is, a bipolar acoustic pulse with the 'pancake' directivity, and, on the other hand, fulfill practical issues such as ease of deployment and operation. This is a non-trivial problem since it requires directive transducer with cylindrical symmetry for a broadband frequency range. Classical solutions using linear arrays of acoustic transducers result in long arrays with many elements, which increase the cost and the complexity for deployment and operation. In this paper we present the extension of our previous R&D studies using the parametric acoustic source technique by dealing with the cylindrical symmetry, and demonstrating that it is possible to use this technique for havin...

  14. Acoustic nuclear magnetic resonance in easy-axis antiferromagnets

    Obtained and investigated is the dispersion equation which shows that in the rouge of the tipping field at low temperatures the study of effects conditioned by the bond between the oscillations of electron and nuclear spins depends upon the fact, whethe the interaction of the sound with a nuclear spin subsystem is taken into account. The same concerns the effects conditioned by a strong bond between the oscillations of the lattice and electron spins. Shown is the effect of anisotropy of magnitostriction relative part on the nature of orientation phase transitions and the value of the coefficient of strengthening nuclear magnetic resonance

  15. Interaction of reed and acoustic resonator in clarinetlike systems.

    Silva, Fabrice; Kergomard, Jean; Vergez, Christophe; Gilbert, Joël

    2008-11-01

    Sound emergence in clarinetlike instruments is investigated in terms of instability of the static regime. Various models of reed-bore coupling are considered, from the pioneering work of Wilson and Beavers ["Operating modes of the clarinet," J. Acoust. Soc. Am. 56, 653-658 (1974)] to more recent modeling including viscothermal bore losses and vena contracta at the reed inlet. The pressure threshold above which these models may oscillate as well as the frequency of oscillation at threshold are calculated. In addition to Wilson and Beavers' previous conclusions concerning the role of the reed damping in the selection of the register the instrument will play on, the influence of the reed motion induced flow is also emphasized, particularly its effect on playing frequencies, contributing to reduce discrepancies between Wilson and Beavers' experimental results and theory, despite discrepancies still remain concerning the pressure threshold. Finally, analytical approximations of the oscillating solution based on Fourier series expansion are obtained in the vicinity of the threshold of oscillation. This allows to emphasize the conditions which determine the nature of the bifurcation (direct or inverse) through which the note may emerge, with therefore important consequences on the musical playing performances. PMID:19045811

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

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

    2009-01-01

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

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

    Tadesse, Semere Ayalew; Li, Mo

    2014-01-01

    Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally, these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acousto-optic coupling in nanophotonic devices. Here we demonstrate microwave frequency surface acoustic wave transducers co-integrated with nanophotonic resonators on piezoelectric aluminum nitride substrates. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength is achieved. The phase and modal matching conditions in this scheme are investigated for efficient modulation. The new acousto-optic platform can lead to novel optical devices based on nonlinear Brillouin processes and provides a direct, wideband link between optical and microwave photons for microwave photonics and quantum optomechanics. PMID:25400144

  18. Non-contact liquid level measurement with electromagnetic–acoustic resonator sensors

    Electromagnetic–acoustic transduction represents an alternative to piezoelectric transduction with unique properties and advantages for resonator sensors. We have shown that such devices are suitable as mass microbalances similar to quartz crystal resonators, and as liquid density and viscosity sensors by exciting a suitable in-plane mode featuring dominant shear vibration. Generating out-of-plane vibrations we have applied these devices also as liquid level sensors. In contrast to classic time-of-flight ultrasonic liquid level sensors, the resolution is not limited by the wavelength, since small frequency changes due to interference effects with a standing acoustic wave are evaluated. For this contribution we have extensively evaluated this liquid level sensing and will present and compare new measurement and modeling results. The model comprises electromagnetic–acoustic interaction with a lossy transmission line representing the acoustic wave in the liquid. In impedance measurements with standard lab equipment a resolution as low as 3 µm at a liquid level of 10 mm and an operating frequency of 275 kHz has been achieved

  19. Test of a virtual cylindrical acoustic resonator for determining the Boltzmann constant

    Feng, X. J.; Lin, H.; Gillis, K. A.; Moldover, M. R.; Zhang, J. T.

    2015-10-01

    We report progress toward determining the Boltzmann constant kB using the concept of a virtual acoustic resonator, a hypothetical resonator that is mathematically equivalent to a cylindrical cavity with periodic boundary conditions. We derived the virtual resonator by combining the measured frequencies of the longitudinal acoustic modes of two argon-filled, cylindrical cavity resonators in such a way to minimize the effects of the cavities’ ends, including transducers and ducts attached to the ends. The cavities had lengths of 80 mm and 160 mm and were operated in their longitudinal (ℓ,0,0) modes. We explored virtual resonators that combine modes of the two resonators that have nearly the same frequencies. The virtual resonator formed from the (2,0,0) mode of the 80 mm resonator combined with the (4,0,0) mode of the 160 mm resonator yielded a value for kB that is, fractionally, only (0.2  ±  1.5)  ×  10-6 larger than the 2010 CODATA-recommended value of kB. (The estimated uncertainty is one standard uncertainty corresponding to a 68% confidence level.) The same virtual resonator yielded values of the pressure derivatives of the speed of sound c in argon, (∂c2/∂p)T and (∂c2/∂p2)T, that differed from literature values by 1% and 2%, respectively. By comparison, when each cavity was considered separately, the values of kB, (∂c2/∂p)T, and (∂c2/∂p2)T differed from literature values by up to 7 ppm, 10%, and 5%, respectively. However, combining the results from the (3,0,0) or (4,0,0) modes of shorter resonator with the results from the (6,0,0) or (8,0,0) modes of the longer resonator yielded incorrect values of kB that varied from run-to-run. We speculate that these puzzling results originated in an unmodeled coupling, either between the two cavities (that resonated at nearly identical resonance frequencies in the same pressure vessel) or between the cavities and modes of the pressure vessel.

  20. Vibration optimization of ZnO thin film bulk acoustic resonator with ring electrodes

    Zhao, Zinan; Qian, Zhenghua; Wang, Bin

    2016-04-01

    A rectangular ZnO thin film bulk acoustic resonator with ring electrodes is presented in this paper to demonstrate the existence of a nearly uniform displacement distribution at the central part of this typical resonator. The variational formulation based on two-dimensional scalar differential equations provides a theoretical foundation for the Ritz method adopted in our analysis. The resonant frequencies and vibration distributions for the thickness-extensional modes of this ring electrode resonator are obtained. The structural parameters are optimized to achieve a more uniform displacement distribution and therefore a uniform mass sensitivity, which guarantee the high accuracy and repeatable measurement for sensor detection in an air or a liquid environment. These results provide a fundamental reference for the design and optimization of the high quality sensor.

  1. Acoustic resonance spectroscopy (ARS): ARS300 operations manual, software version 2.01

    NONE

    1996-07-25

    Acoustic Resonance Spectroscopy (ARS) is a nondestructive evaluation technology developed at the Los Alamos National Laboratory. The ARS technique is a fast, safe, and nonintrusive technique that is particularly useful when a large number of objects need to be tested. Any physical object, whether solid, hollow, or fluid filled, has many modes of vibration. These modes of vibration, commonly referred to as the natural resonant modes or resonant frequencies, are determined by the object`s shape, size, and physical properties, such as elastic moduli, speed of sound, and density. If the object is mechanically excited at frequencies corresponding to its characteristic natural vibrational modes, a resonance effect can be observed when small excitation energies produce large amplitude vibrations in the object. At other excitation frequencies, i.e., vibrational response of the object is minimal.

  2. Orientation fluctuation trend of Pt and ZnO layers in film bulk acoustic resonator

    ZnO-based film bulk acoustic resonator (FBAR) was fabricated with many ZnO/Pt layers by magnetron sputtering. All the layers are good crystallized and highly textured. By crystallographic test, the orientation fluctuation of Pt layer increases with increasing film thickness or stack layers, whereas that of ZnO layer decreases slightly. It is consistent with ZnO grain c-axis tilting observed using transmission electron microscopy. Due to these good quality layers, the device has a high resonate frequency of 3.94 GHz

  3. A new model for nonlinear acoustic waves in a non-uniform lattice of Helmholtz resonators

    Mercier, Jean-François

    2016-01-01

    Propagation of high amplitude acoustic pulses is studied in a 1D waveguide, connected to a lattice of Helmholtz resonators. An homogenized model has been proposed by Sugimoto (J. Fluid. Mech., 244 (1992)), taking into account both the nonlinear wave propagation and various mechanisms of dissipation. This model is extended to take into account two important features: resonators of different strengths and back-scattering effects. The new model is derived and is proved to satisfy an energy balance principle. A numerical method is developed and a better agreement between numerical and experimental results is obtained.

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

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

  5. Varying the agglomeration position of particles in a micro-channel using Acoustic Radiation Force beyond the resonance condition.

    Dron, Olivier; Aider, Jean-Luc

    2013-09-01

    It is well-known that particles can be focused at mid-height of a micro-channel using Acoustic Radiation Force (ARF) tuned at the resonance frequency (h=λ/2). The resonance condition is a strong limitation to the use of acoustophoresis (particles manipulation using acoustic force) in many applications. In this study we show that it is possible to focus the particles anywhere along the height of a micro-channel just by varying the acoustic frequency, in contradiction with the resonance condition. This result has been thoroughly checked experimentally. The different physical properties as well as wall materials have been changed. The wall materials is finally the only critical parameters. One of the specificity of the micro-channel is the thickness of the carrier and reflector layer. A preliminary analysis of the experimental results suggests that the acoustic focusing beyond the classic resonance condition can be explained in the framework of the multilayered resonator proposed by Hill [1]. Nevertheless, further numerical studies are needed in order to confirm and fully understand how the acoustic pressure node can be moved over the entire height of the micro channel by varying the acoustic frequency. Despite some uncertainties about the origin of the phenomenon, it is robust and can be used for improved acoustic sorting or manipulation of particles or biological cells in confined set-ups. PMID:23628114

  6. Phonon-magnon resonant processes with relevance to acoustic spin pumping

    Deymier, P. A.

    2014-12-23

    The recently described phenomenon of resonant acoustic spin pumping is due to resonant coupling between an incident elastic wave and spin waves in a ferromagnetic medium. A classical one-dimensional discrete model of a ferromagnet with two forms of magnetoelastic coupling is treated to shed light on the conditions for resonance between phonons and magnons. Nonlinear phonon-magnon interactions in the case of a coupling restricted to diagonal terms in the components of the spin degrees of freedom are analyzed within the framework of the multiple timescale perturbation theory. In that case, one-phonon-two-magnon resonances are the dominant mechanism for pumping. The effect of coupling on the dispersion relations depends on the square of the amplitude of the phonon and magnon excitations. A straightforward analysis of a linear phonon-magnon interaction in the case of a magnetoelastic coupling restricted to off-diagonal terms in the components of the spins shows a one-phonon to one-magnon resonance as the pumping mechanism. The resonant dispersion relations are independent of the amplitude of the waves. In both cases, when an elastic wave with a fixed frequency is used to stimulate magnons, application of an external magnetic field can be used to approach resonant conditions. Both resonance conditions exhibit the same type of dependency on the strength of an applied magnetic field.

  7. Fabrication of Capacitive Acoustic Resonators Combining 3D Printing and 2D Inkjet Printing Techniques

    Rubaiyet Iftekharul Haque

    2015-10-01

    Full Text Available A capacitive acoustic resonator developed by combining three-dimensional (3D printing and two-dimensional (2D printed electronics technique is described. During this work, a patterned bottom structure with rigid backplate and cavity is fabricated directly by a 3D printing method, and then a direct write inkjet printing technique has been employed to print a silver conductive layer. A novel approach has been used to fabricate a diaphragm for the acoustic sensor as well, where the conductive layer is inkjet-printed on a pre-stressed thin organic film. After assembly, the resulting structure contains an electrically conductive diaphragm positioned at a distance from a fixed bottom electrode separated by a spacer. Measurements confirm that the transducer acts as capacitor. The deflection of the diaphragm in response to the incident acoustic single was observed by a laser Doppler vibrometer and the corresponding change of capacitance has been calculated, which is then compared with the numerical result. Observation confirms that the device performs as a resonator and provides adequate sensitivity and selectivity at its resonance frequency.

  8. Fabrication of capacitive acoustic resonators combining 3D printing and 2D inkjet printing techniques.

    Haque, Rubaiyet Iftekharul; Ogam, Erick; Loussert, Christophe; Benaben, Patrick; Boddaert, Xavier

    2015-01-01

    A capacitive acoustic resonator developed by combining three-dimensional (3D) printing and two-dimensional (2D) printed electronics technique is described. During this work, a patterned bottom structure with rigid backplate and cavity is fabricated directly by a 3D printing method, and then a direct write inkjet printing technique has been employed to print a silver conductive layer. A novel approach has been used to fabricate a diaphragm for the acoustic sensor as well, where the conductive layer is inkjet-printed on a pre-stressed thin organic film. After assembly, the resulting structure contains an electrically conductive diaphragm positioned at a distance from a fixed bottom electrode separated by a spacer. Measurements confirm that the transducer acts as capacitor. The deflection of the diaphragm in response to the incident acoustic single was observed by a laser Doppler vibrometer and the corresponding change of capacitance has been calculated, which is then compared with the numerical result. Observation confirms that the device performs as a resonator and provides adequate sensitivity and selectivity at its resonance frequency. PMID:26473878

  9. Acoustic communication and sound degradation: how do the individual signatures of male and female zebra finch calls transmit over distance?

    Solveig C Mouterde

    Full Text Available BACKGROUND: Assessing the active space of the various types of information encoded by songbirds' vocalizations is important to address questions related to species ecology (e.g. spacing of individuals, as well as social behavior (e.g. territorial and/or mating strategies. Up to now, most of the previous studies have investigated the degradation of species-specific related information (species identity, and there is a gap of knowledge of how finer-grained information (e.g. individual identity can transmit through the environment. Here we studied how the individual signature coded in the zebra finch long distance contact call degrades with propagation. METHODOLOGY: We performed sound transmission experiments of zebra finches' distance calls at various propagation distances. The propagated calls were analyzed using discriminant function analyses on a set of analytical parameters describing separately the spectral and temporal envelopes, as well as on a complete spectrographic representation of the signals. RESULTS/CONCLUSION: We found that individual signature is remarkably resistant to propagation as caller identity can be recovered even at distances greater than a hundred meters. Male calls show stronger discriminability at long distances than female calls, and this difference can be explained by the more pronounced frequency modulation found in their calls. In both sexes, individual information is carried redundantly using multiple acoustical features. Interestingly, features providing the highest discrimination at short distances are not the same ones that provide the highest discrimination at long distances.

  10. Enhancing nuclear quadrupole resonance (NQR) signature detection leveraging interference suppression algorithms

    DeBardelaben, James A.; Miller, Jeremy K.; Myrick, Wilbur L.; Miller, Joel B.; Gilbreath, G. Charmaine; Bajramaj, Blerta

    2012-06-01

    Nuclear quadrupole resonance (NQR) is a radio frequency (RF) magnetic spectroscopic technique that has been shown to detect and identify a wide range of explosive materials containing quadrupolar nuclei. The NQR response signal provides a unique signature of the material of interest. The signal is, however, very weak and can be masked by non-stationary RF interference (RFI) and thermal noise, limiting detection distance. In this paper, we investigate the bounds on the NQR detection range for ammonium nitrate. We leverage a low-cost RFI data acquisition system composed of inexpensive B-field sensing and commercial-off-the-shelf (COTS) software-defined radios (SDR). Using collected data as RFI reference signals, we apply adaptive filtering algorithms to mitigate RFI and enable NQR detection techniques to approach theoretical range bounds in tactical environments.

  11. Low Mach number prediction of the acoustic signature of fractal-generated turbulence

    Laizet, Sylvain, E-mail: s.laizet@imperial.ac.uk [Turbulence, Mixing and Flow Control Group, Department of Aeronautics, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Fortune, Veronique, E-mail: veronique.fortune@lea.univ-poitiers.fr [Department of Fluid Flow, Heat Transfer and Combustion, Institute PPRIME, Universite de Poitiers, ENSMA, CNRS, Teleport 2 - Bd. Marie et Pierre Curie, B.P. 30179, 86962 Futuroscope Chasseneuil Cedex (France); Lamballais, Eric, E-mail: lamballais@univ-poitiers.fr [Department of Fluid Flow, Heat Transfer and Combustion, Institute PPRIME, Universite de Poitiers, ENSMA, CNRS, Teleport 2 - Bd. Marie et Pierre Curie, B.P. 30179, 86962 Futuroscope Chasseneuil Cedex (France); Vassilicos, John Christos, E-mail: j.c.vassilicos@imperial.ac.uk [Turbulence, Mixing and Flow Control Group, Department of Aeronautics, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Acoustic properties of a fractal square grid and regular grid. Black-Right-Pointing-Pointer Hybrid approach based on Lighthill's analogy and Direct Numerical Simulation. Black-Right-Pointing-Pointer Noise reduction for the fractal square grid. Black-Right-Pointing-Pointer Well-defined peak at a Strouhal number between 0.2 and 0.3 for the fractal square grid, absent for the regular grid. - Abstract: In this work, we compare the acoustic properties of a fractal square grid with those of a regular grid by means of a hybrid approach based on Lighthill's analogy and Direct Numerical Simulation (DNS). Our results show that the sound levels corresponding to our fractal square grid of three fractal iterations are significantly reduced by comparison to a regular grid of same porosity and mesh-based Reynolds number. We also find a well-defined peak at a Strouhal number between 0.2 and 0.3 in the acoustic spectrum of our fractal square grid which is absent in the case of our regular grid. We explain this effect in terms of a new criterion for quasi-periodic vortex shedding from a regular or fractal grid.

  12. Acoustic signatures of the phases and phase transitions in Yb2Ti2O7

    Bhattacharjee, Subhro; Erfanifam, S.; Green, E. L.; Naumann, M.; Wang, Zhaosheng; Granovsky, S.; Doerr, M.; Wosnitza, J.; Zvyagin, A. A.; Moessner, R.; Maljuk, A.; Wurmehl, S.; Büchner, B.; Zherlitsyn, S.

    2016-04-01

    We report on measurements of the sound velocity and attenuation in a single crystal of the candidate quantum-spin-ice material Yb2Ti2O7 as a function of temperature and magnetic field. The acoustic modes couple to the spins magnetoelastically and, hence, carry information about the spin correlations that sheds light on the intricate magnetic phase diagram of Yb2Ti2O7 and the nature of spin dynamics in the material. Particularly, we find a pronounced thermal hysteresis in the acoustic data with a concomitant peak in the specific heat indicating a possible first-order phase transition at about 0.17 K. At low temperatures, the acoustic response to magnetic field saturates hinting at the development of magnetic order. The experimental data are consistent with a first-order phase transition from a cooperative paramagnet to a ferromagnet below T ≈0.17 K, as shown by fitting the data with a phenomenological mean-field theory.

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

    Kim, Kyungrim; Zhang, Shujun; Jiang, Xiaoning

    2012-11-01

    Pb(In(0.5)Nb(0.5))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) resonators for surface acoustic load sensing are presented in this paper. Different acoustic loads are applied to thickness mode, thickness-shear mode, and face-shear mode resonators, and the electrical impedances at resonance and anti-resonance frequencies are recorded. More than one order of magnitude higher sensitivity (ratio of electrical impedance change to surface acoustic impedance change) at the resonance is achieved for the face-shear-mode resonator compared with other resonators with the same dimensions. The Krimholtz, Leedom, and Matthaei (KLM) model is used to verify the surface acoustic loading effect on the electrical impedance spectrum of face-shear PIN-PMN-PT single-crystal resonators. The demonstrated high sensitivity of face-shear mode resonators to surface loads is promising for a broad range of applications, including artificial skin, biological and chemical sensors, touch screens, and other touch-based sensors. PMID:23192819

  14. A portable blood plasma clot micro-elastometry device based on resonant acoustic spectroscopy

    Krebs, C. R.; Li, Ling; Wolberg, Alisa S.; Oldenburg, Amy L.

    2015-07-01

    Abnormal blood clot stiffness is an important indicator of coagulation disorders arising from a variety of cardiovascular diseases and drug treatments. Here, we present a portable instrument for elastometry of microliter volume blood samples based upon the principle of resonant acoustic spectroscopy, where a sample of well-defined dimensions exhibits a fundamental longitudinal resonance mode proportional to the square root of the Young's modulus. In contrast to commercial thromboelastography, the resonant acoustic method offers improved repeatability and accuracy due to the high signal-to-noise ratio of the resonant vibration. We review the measurement principles and the design of a magnetically actuated microbead force transducer applying between 23 pN and 6.7 nN, providing a wide dynamic range of elastic moduli (3 Pa-27 kPa) appropriate for measurement of clot elastic modulus (CEM). An automated and portable device, the CEMport, is introduced and implemented using a 2 nm resolution displacement sensor with demonstrated accuracy and precision of 3% and 2%, respectively, of CEM in biogels. Importantly, the small strains (disorders, potentially leading to improved diagnostics and therapeutic monitoring.

  15. Homogenization of locally resonant acoustic metamaterials towards an emergent enriched continuum

    Sridhar, A.; Kouznetsova, V. G.; Geers, M. G. D.

    2016-03-01

    This contribution presents a novel homogenization technique for modeling heterogeneous materials with micro-inertia effects such as locally resonant acoustic metamaterials. Linear elastodynamics is used to model the micro and macro scale problems and an extended first order Computational Homogenization framework is used to establish the coupling. Craig Bampton Mode Synthesis is then applied to solve and eliminate the microscale problem, resulting in a compact closed form description of the microdynamics that accurately captures the Local Resonance phenomena. The resulting equations represent an enriched continuum in which additional kinematic degrees of freedom emerge to account for Local Resonance effects which would otherwise be absent in a classical continuum. Such an approach retains the accuracy and robustness offered by a standard Computational Homogenization implementation, whereby the problem and the computational time are reduced to the on-line solution of one scale only.

  16. Efficient Structure Resonance Energy Transfer from Microwaves to Confined Acoustic Vibrations in Viruses

    Yang, Szu-Chi; Lin, Huan-Chun; Liu, Tzu-Ming; Lu, Jen-Tang; Hung, Wan-Ting; Huang, Yu-Ru; Tsai, Yi-Chun; Kao, Chuan-Liang; Chen, Shih-Yuan; Sun, Chi-Kuang

    2015-12-01

    Virus is known to resonate in the confined-acoustic dipolar mode with microwave of the same frequency. However this effect was not considered in previous virus-microwave interaction studies and microwave-based virus epidemic prevention. Here we show that this structure-resonant energy transfer effect from microwaves to virus can be efficient enough so that airborne virus was inactivated with reasonable microwave power density safe for the open public. We demonstrate this effect by measuring the residual viral infectivity of influenza A virus after illuminating microwaves with different frequencies and powers. We also established a theoretical model to estimate the microwaves power threshold for virus inactivation and good agreement with experiments was obtained. Such structure-resonant energy transfer induced inactivation is mainly through physically fracturing the virus structure, which was confirmed by real-time reverse transcription polymerase chain reaction. These results provide a pathway toward establishing a new epidemic prevention strategy in open public for airborne virus.

  17. Development of numerical analysis method of flow-acoustic resonance in stub pipes of safety relief valves

    The boiling water reactors (BWRs) have steam dryer in the upper part of the pressure vessel to remove moisture from the steam. The steam dryer in the Quad Cities Unit 2 nuclear power plant was damaged by high-cycle fatigue due to acoustic-induced vibration during extended power uprate operation. The principal source of the acoustic-induced vibration was flow-acoustic resonance at the stub pipes of the safety relief valves (SRVs) in the main steam lines (MSLs). The acoustic wave generated at the SRV stub pipes propagates throughout the MSLs and eventually reaches and damages the steam dryer. Therefore, for power uprate operation of the BWRs, it has been required to predict the flow-acoustic resonance at the SRV stub pipes. The purpose of this article was to propose a numerical analysis method for evaluating the flow-acoustic resonance in the SRV stub pipes. The proposed method is based on the finite difference lattice Boltzmann method (FDLBM). So far, the FDLBM has been applied to flow-acoustic simulations of laminar flows around simple geometries at low Reynolds number. In order to apply the FDLBM to the flow-acoustic resonance simulations of turbulent flows around complicated geometries at the high Reynolds number, we developed computationally efficient model by introducing new function into the governing equation. The proposed method was compared with the conventional FDLBM in the cavity-driven flow simulation. The proposed method was validated by comparisons with the experimental data in the 1/10-scale test of BWR-5 under atmosphere condition. The following three results were obtained; the first is that the proposed method can reduce the computing time by 30% compared with the conventional FDLBM; the second is that the proposed method successfully simulated the flow-acoustic resonance in the SRV stub pipes of the BWR-5, and the pressure fluctuations of the simulation results agreed well with those of the experimental data; and the third is the mechanism of the

  18. A comparison of methods for 3D target localization from seismic and acoustic signatures

    ELBRING,GREGORY J.; GARBIN,H. DOUGLAS; LADD,MARK D.

    2000-04-03

    An important application of seismic and acoustic unattended ground sensors (UGS) is the estimation of the three dimensional position of an emitting target. Seismic and acoustic data derived from UGS systems provide the taw information to determine these locations, but can be processed and analyzed in a number of ways using varying amounts of auxiliary information. Processing methods to improve arrival time picking for continuous wave sources and methods for determining and defining the seismic velocity model are the primary variables affecting the localization accuracy. Results using field data collected from an underground facility have shown that using an iterative time picking technique significantly improves the accuracy of the resulting derived target location. Other processing techniques show little advantage over simple crosscorrelation along in terms of accuracy, but may improve the ease with which time picks can be made. An average velocity model found through passive listening or a velocity model determined from a calibration source near the target source both result in similar location accuracies, although the use of station correction severely increases the location error.

  19. A flow visualization study of flow-acoustic coupling at the mouth of a resonant side-branch

    Flow-excited acoustic resonances of piping systems containing closed side-branches are often encountered in power stations, gas transport pipelines, chemical plants, compressor installations, and other industrial applications. The coupling of a shear layer with the sound field of a resonant side-branch has been investigated by means of an extensive flow visualization study under controlled excitation level and frequency. The interaction mechanism is visualized at several Strouhal numbers corresponding to: (a) before the onset of resonance; (b) within the lock-in range; (c) in the hysteresis region; and (d) after the subsidence of resonance. It is shown that the instantaneous position and phase speed of the shear layer vortices are strongly dependent on the Strouhal number and the amplitude of the acoustic particle velocity. Moreover, the phase speed has been found to be not constant over the oscillation cycle. These findings have important implications when modeling flow-acoustic interaction at large amplitude acoustic pulsations. The study has shed more light also on the phenomenon of hysteresis as well as on the mechanism of vortex damping which limits the amplitude of pulsation when the system losses become negligibly small. The flow visualization results give support to the argument made by other researchers that the mechanism of acoustic resonance is different from that which causes the non-resonant oscillations of impinging shear flows

  20. Investigation of the ocean acoustic signatures from strong explosions at a long distance in the ocean sound channel by computer simulation

    The identification and location of ocean acoustic signatures are the principal objectives of a program to discourage clandestine testing of nuclear explosives. Difficulties arise primarily from variations in the water column. In turn, these variations affect acoustic propagation in the SOFAR channel. In this study, the path effects on the signals generated by strong explosions (1 and 10 kn) are investigated. The goal is to make a quantitative correlation between the initial source description and the final acoustical signatures received at a great distance under various conditions. The study is performed entirely by computer simulations applying two computer programs in succession. First, the explosions are simulated by a 2-D hydrodynamic computer program, CALE, which was originally developed to calculate astrophysical problems. The computed signals have reached more than 700 m deep approaching the SOFAR channel. At this point, the CALE output is linked to a hydro-acoustic computer program, the NPE code, by which wave propagation in the SOFAR channel is modeled. The NPE code was developed at the Naval Research Laboratory to study ocean acoustics. [Work supported by the U. S. Department of Energy under Contract No. W-7405-ENG-48.

  1. A passively tunable non-resonant acoustic metamaterial lens for selective ultrasonic excitation

    Zhu, Hongfei

    2014-01-01

    In this paper, we present an approach to ultrasonic beam-forming and beam-steering in structures based on the concept of embedded non-resonant acoustic metamaterial lenses. The lens design exploits the principle of acoustic drop-channel which enables the dynamic coupling of multiple ultrasonic waveguides at selected frequencies. In contrast with currently available technology, the embedded lens allows generating directional excitation by means of a single ultrasonic transducer. The lens design and performance are numerically investigated by using Plane Wave Expansion and Finite Difference Time Domain techniques applied to bulk structures. Then, the design is experimentally validated on a thin aluminum plate where the lens is implemented by through-holes. The dynamic response of the embedded lens is estimated by reconstructing, via Laser Vibrometry, the velocity field induced by a piezoelectric shaker source.

  2. Non destructive testing by acoustic signature of damage level in 304L steel samples submitted to rolling, tensile test and thermal annealing treatments

    The aim of this work is to demonstrate the ability of acoustic signature technique to detect in a non-destructive way mechanical property variations due to damage of the internal material structure for 304L steel samples, provided by EDF company. For this purpose, the velocity and the attenuation of Rayleigh acoustic waves have been measured for rolled, drawn and thermally treated samples. Complementary information provided by echography have also been used to calculate the corresponding variations of the dynamic Young's modulus E

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

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

    2016-02-01

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

  4. A wireless interrogation system exploiting narrowband acoustic resonator for remote physical quantity measurement

    Friedt, J.-M [SENSeOR, 32 Avenue de l' Observatoire, 25044 Besancon (France); Droit, C.; Martin, G.; Ballandras, S. [Department of Time and Frequency, FEMTO-ST, 32 Avenue de l' Observatoire, 25044 Besancon (France)

    2010-01-15

    Monitoring physical quantities using acoustic wave devices can be advantageously achieved using the wave characteristic dependence to various parametric perturbations (temperature, stress, and pressure). Surface acoustic wave (SAW) resonators are particularly well suited to such applications as their resonance frequency is directly influenced by these perturbations, modifying both the phase velocity and resonance conditions. Moreover, the intrinsic radio frequency (rf) nature of these devices makes them ideal for wireless applications, mainly exploiting antennas reciprocity and piezoelectric reversibility. In this paper, we present a wireless SAW sensor interrogation unit operating in the 434 MHz centered ISM band--selected as a tradeoff between antenna dimensions and electromagnetic wave penetration in dielectric media--based on the principles of a frequency sweep network analyzer. We particularly focus on the compliance with the ISM standard which reveals complicated by the need for switching from emission to reception modes similarly to radar operation. In this matter, we propose a fully digital rf synthesis chain to develop various interrogation strategies to overcome the corresponding difficulties and comply with the above-mentioned standard. We finally assess the reader interrogation range, accuracy, and dynamics.

  5. Investigating the emotional response to room acoustics: A functional magnetic resonance imaging study.

    Lawless, M S; Vigeant, M C

    2015-10-01

    While previous research has demonstrated the powerful influence of pleasant and unpleasant music on emotions, the present study utilizes functional magnetic resonance imaging (fMRI) to assess the positive and negative emotional responses as demonstrated in the brain when listening to music convolved with varying room acoustic conditions. During fMRI scans, subjects rated auralizations created in a simulated concert hall with varying reverberation times. The analysis detected activations in the dorsal striatum, a region associated with anticipation of reward, for two individuals for the highest rated stimulus, though no activations were found for regions associated with negative emotions in any subject. PMID:26520354

  6. Negative refraction realized by band folding effect in resonator-based acoustic metamaterials

    Liu, Jiao; Hou, Zhilin; Fu, Xiujun

    2015-09-01

    We show in the paper that a two-dimensional acoustic metamaterial with isotropic negative refraction band at subwavelength scale can be constructed simply by arranging only one kind of Helmholtz resonators into honeycomb-like lattice. To understand the phenomenon, the mechanism for double negative metamaterial is investigated. We point out that double negative metamaterials can be obtained only when the phase accumulating over their constructive unit cell becomes greater than π but smaller than 2π. Based on the understanding, we attribute the negative refraction phenomenon in our suggested structure as a result of the band folding effect.

  7. Acoustic emission and acousto-ultrasonic signature analysis of failure mechanisms in carbon fiber reinforced polymer materials

    Carey, Shawn Allen

    Fiber reinforced polymer composite materials, particularly carbon (CFRPs), are being used for primary structural applications, particularly in the aerospace and naval industries. Advantages of CFRP materials, compared to traditional materials such as steel and aluminum, include: light weight, high strength to weight ratio, corrosion resistance, and long life expectancy. A concern with CFRPs is that despite quality control during fabrication, the material can contain many hidden internal flaws. These flaws in combination with unseen damage due to fatigue and low velocity impact have led to catastrophic failure of structures and components. Therefore a large amount of research has been conducted regarding nondestructive testing (NDT) and structural health monitoring (SHM) of CFRP materials. The principal objective of this research program was to develop methods to characterize failure mechanisms in CFRP materials used by the U.S. Army using acoustic emission (AE) and/or acousto-ultrasonic (AU) data. Failure mechanisms addressed include fiber breakage, matrix cracking, and delamination due to shear between layers. CFRP specimens were fabricated and tested in uniaxial tension to obtain AE and AU data. The specimens were designed with carbon fibers in different orientations to produce the different failure mechanisms. Some specimens were impacted with a blunt indenter prior to testing to simulate low-velocity impact. A signature analysis program was developed to characterize the AE data based on data examination using visual pattern recognition techniques. It was determined that it was important to characterize the AE event , using the location of the event as a parameter, rather than just the AE hit (signal recorded by an AE sensor). A back propagation neural network was also trained based on the results of the signature analysis program. Damage observed on the specimens visually with the aid of a scanning electron microscope agreed with the damage type assigned by the

  8. Resonant modal group theory of membrane-type acoustical metamaterials for low-frequency sound attenuation

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

    2015-09-01

    In order to overcome the influence of the structural resonance on the continuous structures and obtain a lightweight thin-layer structure which can effectively isolate the low-frequency noises, an elastic membrane structure was proposed. In the low-frequency range below 500 Hz, the sound transmission loss (STL) of this membrane type structure is greatly higher than that of the current sound insulation material EVA (ethylene-vinyl acetate copo) of vehicle, so it is possible to replace the EVA by the membrane-type metamaterial structure in practice engineering. Based on the band structure, modal shapes, as well as the sound transmission simulation, the sound insulation mechanism of the designed membrane-type acoustic metamaterials was analyzed from a new perspective, which had been validated experimentally. It is suggested that in the frequency range above 200 Hz for this membrane-mass type structure, the sound insulation effect was principally not due to the low-level locally resonant mode of the mass block, but the continuous vertical resonant modes of the localized membrane. So based on such a physical property, a resonant modal group theory is initially proposed in this paper. In addition, the sound insulation mechanism of the membrane-type structure and thin plate structure were combined by the membrane/plate resonant theory.

  9. Resonant acoustic frequencies of a tandem cascade. Part 1. Zero relative motion

    Woodley, B. M.; Peake, N.

    1999-08-01

    In this paper we study the acoustic scattering between two flat-plate cascades, with the aim of investigating the possible existence of trapped modes. In practical terms this question is related to the phenomenon of acoustic resonance in turbomachinery, whereby such resonant modes are excited to large amplitude by unsteady processes such as vortex shedding. We use the Wiener Hopf technique to analyse the scattering of the various wave fields by the cascade blades, and by considering the fields between adjacent blades, as well as between the cascades, we are able to take full account of the genuinely finite blade chords. Analytic expressions for the various scattering matrices are derived, and an infinite-dimensional matrix equation is formed, which is then investigated numerically for singularity. One advantage of this formulation is that it allows the constituent parts of the system to be analysed individually, so that for instance the behaviour of the gap between the blade rows alone can be investigated by omitting the finite-chord terms in the equations. We demonstrate that the system exhibits two types of resonance, at a wide range of parameter values. First, there is a cut-on/cut-off resonance associated with the gap between the rows, and corresponding to modes propagating parallel to the front face of the cascades. Second, there is a resonance of the downstream row, akin to a Parker mode, driven at low frequencies by a vorticity wave produced by trapped duct modes in the upstream row, and at higher frequencies by radiation modes (and the vorticity wave) between the blade rows. The predictions for this second set of resonances are shown to be in excellent agreement with previous experimental data. The resonant frequencies are also seen to be real for this twin cascade system, indicating that the resonances correspond to genuine trapped modes. The analysis in this paper is completed with non-zero axial flow but with zero relative rotation between the cascades

  10. Acoustic emission signature analysis. Technical progress report No. 2, 1 March 1979-29 February 1980

    Acoustic emission in plate glass and steel has been studied as a function of angle. The low frequency AE in glass (< 1 MHz) was studied in detail, and contributions from P, S and Rayleigh waves identified. These results are isotropic, as expected theoretically. Limited high frequency (5-20 MHz) results have been obtained in glass. This is the first time, that AE energy has been measured above 3 MHz. The measurement of AE on transgranular crack growth in steel during fatigue crack growth was accomplished by use of a low noise manual hydraulic loading system and an electronic gate to reject grip noise. The signals are complex, and not yet understood in detail. The concept of the wave momentum of an AE, first introduced during the previous year, was elaboratored and a measurement technique suggested. The theoretical study of this problem led to the discovery of an infinite, previously unknown, family of elastic surface (Rayleigh-like) waves, and to further cylindrical, radially propagating plate waves. It appears these waves may be useful in other areas of ultrasonics

  11. Ultrasonic thermometry simulation in a random fluctuating medium: Evidence of the acoustic signature of a one-percent temperature difference.

    Nagaso, M; Moysan, J; Benjeddou, S; Massacret, N; Ploix, M A; Komatitsch, D; Lhuillier, C

    2016-05-01

    We study the development potential of ultrasonic thermometry in a liquid fluctuating sodium environment similar to that present in a Sodium-cooled Fast Reactor, and thus investigate if and how ultrasonic thermometry could be used to monitor the sodium flow at the outlet of the reactor core. In particular we study if small temperature variations in the sodium flow of e.g. about 1% of the sodium temperature, i.e., about 5°C, can have a reliably-measurable acoustic signature. Since to our knowledge no experimental setups are available for such a study, and considering the practical difficulties of experimentation in sodium, we resort to a numerical technique for full wave propagation called the spectral-element method, which is a highly accurate finite-element method owing to the high-degree basis functions it uses. We obtain clear time-of-flight variations in the case of a small temperature difference of one percent in the case of a static temperature gradient as well as in the presence of a random fluctuation of the temperature field in the turbulent flow. The numerical simulations underline the potential of ultrasonic thermometry in such a context. PMID:26921558

  12. Single- and few-layer WTe2 and their suspended nanostructures: Raman signatures and nanomechanical resonances

    Lee, Jaesung; Ye, Fan; Wang, Zenghui; Yang, Rui; Hu, Jin; Mao, Zhiqiang; Wei, Jiang; Feng, Philip X.-L.

    2016-04-01

    Single crystal tungsten ditelluride (WTe2) has recently been discovered to exhibit non-saturating extreme magnetoresistance in bulk; it has also emerged as a new layered material from which atomic layer crystals can be extracted. While atomically thin WTe2 is attractive for its unique properties, little research has been conducted on single- and few-layer WTe2. Here we report the isolation of single- and few-layer WTe2, as well as the fabrication and characterization of the first WTe2 suspended nanostructures. We have observed new Raman signatures of single- and few-layer WTe2 that have been theoretically predicted but have not been reported to date, in both on-substrate and suspended WTe2 flakes. We have further probed the nanomechanical properties of suspended WTe2 structures by measuring their flexural resonances, and obtain a Young's modulus of EY ~ 80 GPa for the suspended WTe2 flakes. This study paves the way for future investigations and utilizations of the multiple new Raman fingerprints of single- and few-layer WTe2, and for explorations of mechanical control of WTe2 atomic layers.

  13. Micromachined silicon and polymer probes integrated with film-bulk-acoustic-resonator mass sensors

    This paper presents a novel micromachined probe with a miniature film-bulk-acoustic-resonator (FBAR) mass sensor integrated at the tip. The detailed fabrication processes for a silicon microprobe and an SU-8 microprobe are described and discussed. The electrical performances of FBARs integrated on both the microprobes were characterized and compared. The semiconducting silicon was found to degrade the FBAR's quality factor (Q) significantly, due to the GHz electromagnetic wave's energy loss in the low-resistivity silicon. Yet, the FBAR on the SU-8 probe was measured to have a higher Q than that on the silicon probe, as the SU-8 polymer material is highly resistive and electrically insulating. As an application demonstration, the fabricated SU-8 probe was successfully used in detecting Hg2+ concentration in liquids. The integration of a resonant mass sensor with a micromachined probe offers easy access to sensing environment with minimal disturbance to the environment

  14. Negative refraction realized by band folding effect in resonator-based acoustic metamaterials

    We show in the paper that a two-dimensional acoustic metamaterial with isotropic negative refraction band at subwavelength scale can be constructed simply by arranging only one kind of Helmholtz resonators into honeycomb-like lattice. To understand the phenomenon, the mechanism for double negative metamaterial is investigated. We point out that double negative metamaterials can be obtained only when the phase accumulating over their constructive unit cell becomes greater than π but smaller than 2π. Based on the understanding, we attribute the negative refraction phenomenon in our suggested structure as a result of the band folding effect. - Highlights: • Negative-refraction structure by only one kind of resonators is suggested. • Directional and isotropic negative band at subwavelength scale are obtained. • The mechanism is understood as the band folding effect. • The influences of the wall friction and thermoviscous diffusive effect are checked

  15. Negative refraction realized by band folding effect in resonator-based acoustic metamaterials

    Liu, Jiao; Hou, Zhilin, E-mail: phzlhou@scut.edu.cn; Fu, Xiujun

    2015-09-25

    We show in the paper that a two-dimensional acoustic metamaterial with isotropic negative refraction band at subwavelength scale can be constructed simply by arranging only one kind of Helmholtz resonators into honeycomb-like lattice. To understand the phenomenon, the mechanism for double negative metamaterial is investigated. We point out that double negative metamaterials can be obtained only when the phase accumulating over their constructive unit cell becomes greater than π but smaller than 2π. Based on the understanding, we attribute the negative refraction phenomenon in our suggested structure as a result of the band folding effect. - Highlights: • Negative-refraction structure by only one kind of resonators is suggested. • Directional and isotropic negative band at subwavelength scale are obtained. • The mechanism is understood as the band folding effect. • The influences of the wall friction and thermoviscous diffusive effect are checked.

  16. General band gap condition in one-dimensional resonator-based acoustic metamaterial

    Liu, Yafei; Hou, Zhilin; Fu, Xiujun

    2016-03-01

    A one-dimensional model for resonator-based acoustic metamaterials is introduced. The condition for band gap in such kind of structure is obtained. According to this condition, the dispersion relation is in general a result of the scattering phase and propagating phase. The phenomenon that the band gap is less dependent on lattice structure appears only in the special system in which the coupling between the resonators and the host medium is weak enough. For strong coupled systems, the dispersion of wave can be significantly adjusted by the propagating phase. Based on the understanding, a general guide for band gap optimization is given and the mechanism for structures with the defect states at subwavelength scale is revealed.

  17. Acoustic resonance scattering by a system of concentrically multilayered shells: the inherent background and resonance coefficients

    Choi, M S; Lee, S H

    1999-01-01

    The inherent background coefficients that exactly describe the background amplitudes in the scattered field have been presented for the scattering of plane acoustic waves by a system of concentrically multilayered solid and/or fluid shells submerged in a fluid. The coefficients have been obtained by replacing the mechanical surface admittance function with the zero-frequency limit of the admittance function for the analogous fluid system, where the shear wave speeds in the solid layers are set to zero. By taking advantage of the concept of incoming and outgoing waves, we find the surface admittance function for the fluid system in such a form that the analytical generalization for any number of layers and the physical interpretation are very easy. The background coefficients obtained are independent of the bulk wave speeds in the system: they depend on the mass densities and the thickness of the shells. With increasing frequency, the inherent background undergoes a transition from the soft to the rigid backgr...

  18. Temperature Frequency Characteristics of Hexamethyldisiloxane (HMDSO) Polymer Coated Rayleigh Surface Acoustic Wave (SAW) Resonators for Gas-Phase Sensor Applications

    Radeva, Ekaterina I.; Esmeryan, Karekin D.; Ivan D. Avramov

    2012-01-01

    Temperature induced frequency shifts may compromise the sensor response of polymer coated acoustic wave gas-phase sensors operating in environments of variable temperature. To correct the sensor data with the temperature response of the sensor the latter must be known. This study presents and discusses temperature frequency characteristics (TFCs) of solid hexamethyldisiloxane (HMDSO) polymer coated sensor resonators using the Rayleigh surface acoustic wave (RSAW) mode on ST-cut quartz. Using ...

  19. Sensitivity of thin-film bulk acoustic resonators (FBAR) to localized mechanical forces

    We report on the sensitivity of thin-film bulk acoustic resonators (FBARs) to localized contact mechanical forces, their design for high sensitivity and the performance under different forcing conditions and mechanisms. Cantilever and membrane structures are the examples chosen for structure and process flow design, finite element modeling and experimental characterization. To leverage on the high sensitivity of FBAR devices at the 2 GHz radio frequency, we carried out electrical bulk acoustic wave excitation and readout of the first longitudinal acoustic mode. Experiments to extract actual sensitivities included atomic force microscopy-driven force excitation, nanoindentation and manual force loading. A force sensitivity function with extracted values S (MHz N−1) from 50 to 270 MHz N−1 shows its dependence on the thin-film stack configuration, the extent of force which determines the linear regime and the spatial location of the force loading source. The discussion provides a force range and sensitivity benchmarking, possible manufacturing and application scenarios, and design guidelines for future integrated devices. (paper)

  20. Combined surface acoustic wave and surface plasmon resonance measurement of collagen and fibrinogen layers

    Friedt, J M; Francis, L; Zhou, C; Campitelli, A; Friedt, Jean-Michel; Denis, Frederic; Francis, Laurent; Zhou, Cheng; Campitelli, Andrew

    2003-01-01

    We use an instrument combining optical (surface plasmon resonance) and acoustic (Love mode acoustic wave device) real-time measurements on a same surface for the identification of water content in collagen and fibrinogen protein layers. After calibration of the surface acoustic wave device sensitivity by copper electrodeposition, the bound mass and its physical properties -- density and optical index -- are extracted from the complementary measurement techniques and lead to thickness and water ratio values compatible with the observed signal shifts. Such results are especially usefully for protein layers with a high water content as shown here for collagen on an hydrophobic surface. We obtain the following results: collagen layers include 70+/-20 % water and are 16+/-3 to 19+/-3 nm thick for bulk concentrations ranging from 30 to 300 ug/ml. Fibrinogen layers include 50+/-10 % water for layer thicknesses in the 6+/-1.5 to 13+/-2 nm range when the bulk concentration is in the 46 to 460 ug/ml range.

  1. Monitoring accelerated carbonation on standard Portland cement mortar by nonlinear resonance acoustic test

    Eiras, J. N.; Kundu, T.; Popovics, J. S.; Monzó, J.; Borrachero, M. V.; Payá, J.

    2015-03-01

    Carbonation is an important deleterious process for concrete structures. Carbonation begins when carbon dioxide (CO2) present in the atmosphere reacts with portlandite producing calcium carbonate (CaCO3). In severe carbonation conditions, C-S-H gel is decomposed into silica gel (SiO2.nH2O) and CaCO3. As a result, concrete pore water pH decreases (usually below 10) and eventually steel reinforcing bars become unprotected from corrosion agents. Usually, the carbonation of the cementing matrix reduces the porosity, because CaCO3 crystals (calcite and vaterite) occupy more volume than portlandite. In this study, an accelerated carbonation-ageing process is conducted on Portland cement mortar samples with water to cement ratio of 0.5. The evolution of the carbonation process on mortar is monitored at different levels of ageing until the mortar is almost fully carbonated. A nondestructive technique based on nonlinear acoustic resonance is used to monitor the variation of the constitutive properties upon carbonation. At selected levels of ageing, the compressive strength is obtained. From fractured surfaces the depth of carbonation is determined with phenolphthalein solution. An image analysis of the fractured surfaces is used to quantify the depth of carbonation. The results from resonant acoustic tests revealed a progressive increase of stiffness and a decrease of material nonlinearity.

  2. Complex Contact-Based Dynamics of Microsphere Monolayers Revealed by Resonant Attenuation of Surface Acoustic Waves

    Hiraiwa, M.; Abi Ghanem, M.; Wallen, S. P.; Khanolkar, A.; Maznev, A. A.; Boechler, N.

    2016-05-01

    Contact-based vibrations play an essential role in the dynamics of granular materials. Significant insights into vibrational granular dynamics have previously been obtained with reduced-dimensional systems containing macroscale particles. We study contact-based vibrations of a two-dimensional monolayer of micron-sized spheres on a solid substrate that forms a microscale granular crystal. Measurements of the resonant attenuation of laser-generated surface acoustic waves reveal three collective vibrational modes that involve displacements and rotations of the microspheres, as well as interparticle and particle-substrate interactions. To identify the modes, we tune the interparticle stiffness, which shifts the frequency of the horizontal-rotational resonances while leaving the vertical resonance unaffected. From the measured contact resonance frequencies we determine both particle-substrate and interparticle contact stiffnesses and find that the former is an order of magnitude larger than the latter. This study paves the way for investigating complex contact-based dynamics of microscale granular crystals and yields a new approach to studying micro- to nanoscale contact mechanics in multiparticle networks.

  3. Super-resolution imaging by resonant tunneling in anisotropic acoustic metamaterials.

    Liu, Aiping; Zhou, Xiaoming; Huang, Guoliang; Hu, Gengkai

    2012-10-01

    The resonant tunneling effects that could result in complete transmission of evanescent waves are examined in acoustic metamaterials of anisotropic effective mass. The tunneling conditions are first derived for the metamaterials composed of classical mass-in-mass structures. It is found that the tunneling transmission occurs when the total length of metamaterials is an integral number of half-wavelengths of the periodic Bloch wave. Due to the local resonance of building units of metamaterials, the Bloch waves are spatially modulated within the periodic structures, leading to the resonant tunneling occurring in the low-frequency region. The metamaterial slab lens with anisotropic effective mass is designed by which the physics of resonant tunneling and the features for evanescent field manipulations are examined. The designed lens interacts with evanescent waves in the way of the propagating wavenumber weakly dependent on the spatial frequency of evanescent waves. Full-wave simulations validate the imaging performance of the proposed lens with the spatial resolution beyond the diffraction limit. PMID:23039546

  4. Acoustic scattering by elastic cylinders of elliptical cross-section and splitting up of resonances

    The scattering of a plane acoustic wave by an infinite elastic cylinder of elliptical cross section is studied from a modal formalism by emphasizing the role of the symmetries. More precisely, as the symmetry is broken in the transition from the infinite circular cylinder to the elliptical one, the splitting up of resonances is observed both theoretically and experimentally. This phenomenon can be interpreted using group theory. The main difficulty stands in the application of this theory within the framework of the vectorial formalism in elastodynamics. This method significantly simplifies the numerical treatment of the problem, provides a full classification of the resonances, and gives a physical interpretation of the splitting up in terms of symmetry breaking. An experimental part based on ultrasonic spectroscopy complements the theoretical study. A series of tank experiments is carried out in the case of aluminium elliptical cylinders immersed in water, in the frequency range 0 ≤ kr ≤ 50, where kr is the reduced wave number in the fluid. The symmetry is broken by selecting various cylinders of increasing eccentricity. More precisely, the greater the eccentricity, the higher the splitting up of resonances is accentuated. The experimental results provide a very good agreement with the theoretical ones, the splitting up is observed on experimental form functions, and the split resonant modes are identified on angular diagrams

  5. Sub-Poissonian phonon statistics in an acoustical resonator coupled to a pumped two-level emitter

    Ceban, V., E-mail: victor.ceban@phys.asm.md; Macovei, M. A., E-mail: macovei@phys.asm.md [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of)

    2015-11-15

    The concept of an acoustical analog of the optical laser has been developed recently in both theoretical and experimental works. We here discuss a model of a coherent phonon generator with a direct signature of the quantum properties of sound vibrations. The considered setup is made of a laser-driven quantum dot embedded in an acoustical nanocavity. The system dynamics is solved for a single phonon mode in the steady-state and in the strong quantum dot—phonon coupling regime beyond the secular approximation. We demonstrate that the phonon statistics exhibits quantum features, i.e., is sub-Poissonian.

  6. Using Combined X-ray Computed Tomography and Acoustic Resonance to Understand Supercritical CO2 Behavior in Fractured Sandstone

    Kneafsey, T. J.; Nakagawa, S.

    2015-12-01

    Distribution of supercritical (sc) CO2 has a large impact on its flow behavior as well as on the properties of seismic waves used for monitoring. Simultaneous imaging of scCO2 distribution in a rock core using X-ray computed tomography (CT) and measurements of seismic waves in the laboratory can help understand how the distribution evolves as scCO2 invades through rock, and the resulting seismic signatures. To this end, we performed a series of laboratory scCO2 core-flood experiments in intact and fractured anisotropic Carbon Tan sandstone samples. In these experiments, we monitored changes in the CO2 saturation distribution and sonic-frequency acoustic resonances (yielding both seismic velocity and attenuation) over the course of the floods. A short-core resonant bar test system (Split-Hopkinson Resonant Bar Apparatus) custom fit into a long X-ray transparent pressure vessel was used for the seismic measurements, and a modified General Electric medical CT scanner was used to acquire X-ray CT data from which scCO2 saturation distributions were determined. The focus of the experiments was on the impact of single fractures on the scCO2 distribution and the seismic properties. For this reason, we examined several cases including 1. intact, 2. a closely mated fracture along the core axis, 3. a sheared fracture along the core axis (both vertical and horizontal for examining the buoyancy effect), and 4. a sheared fracture perpendicular to the core axis. For the intact and closely mated fractured cores, Young's modulus declined with increasing CO2 saturation, and attenuation increased up to about 15% CO2 saturation after which attenuation declined. For cores having wide axial fractures, the Young's modulus was lower than for the intact and closely mated cases, however did not change much with CO2 pore saturation. Much lower CO2 pore saturations were achieved in these cases. Attenuation increased more rapidly however than for the intact sample. For the core

  7. The Fugløy Reef at 70°N; acoustic signature, geologic, geomorphologic and oceanographic setting

    Lindberg, Björn; Berndt, Christian; Mienert, Jürgen

    2007-02-01

    This is the first in-depth study of a cluster of cold-water coral reefs, the Fugløy Reefs, found at 70°N on the Norwegian margin. Combining high-resolution seismic reflection data, side-scan sonar, video-images, and oceanographic measurements reveals the geologic, geomorphologic and oceanographic setting in which the reefs occur. The reefs consist mainly of the scleractinian ahermatypic Lophelia pertusa, and exist below the thermocline at water depths between 140 m and 190 m. The reefs appear as cone-shaped, acoustically transparent features on seismic reflection data, consistently located in places characterized by the availability of hard substrate, high relief, and periodical exposure to high tidal currents (>30 cm/s). These currents transport water of the Norwegian Atlantic Current to the reefs from an area with fluid expulsion-related pockmarks. The spatial relationship between reef, pockmark locations, and current directions suggests that seepage of biogenic gas might be a catalyst to reef growth. With a height of more than 40 m some of the Fugløy reefs are among the highest reported from the Norwegian Margin. This indicates highly favourable growth conditions, and conservative estimates indicate a net growth rate for the reefs of ~5 mm/year. We expect that cold-water reefs will be found further north along the Barents Sea margin as general awareness on the geophysical signature and appearance of the reefs increases, because all known factors involved in reef establishment and growth are within the required intervals also further north.

  8. R and D studies for the development of a compact transmitter able to mimic the acoustic signature of a UHE neutrino interaction

    Calibration of acoustic neutrino telescopes with neutrino-like signals is essential to evaluate the feasibility of the technique and to know the efficiency of the detectors. However, it is not straightforward to have acoustic transmitters that, on one hand, are able to mimic the signature of a UHE neutrino interaction, that is, a bipolar acoustic pulse with the ‘pancake’ directivity, and on the other hand, fulfil practical issues such as ease of deployment and operation. This is a non-trivial problem since it requires directive transducer with cylindrical symmetry for a broadband frequency range. Classical solutions using linear arrays of acoustic transducers result in long arrays with many elements, which increase the cost and the complexity for deployment and operation. In this paper we present the extension of our previous R and D studies using the parametric acoustic source technique by dealing with the cylindrical symmetry and demonstrating that it is possible to use this technique for having a compact solution that could be much more easily included in neutrino telescope infrastructures or used in specific sea campaigns for calibration.

  9. A METHODOLOGY TO INTEGRATE MAGNETIC RESONANCE AND ACOUSTIC MEASUREMENTS FOR RESERVOIR CHARACTERIZATION

    Jorge O. Parra; Chris L. Hackert; Lorna L. Wilson

    2002-09-20

    The work reported herein represents the third year of development efforts on a methodology to interpret magnetic resonance and acoustic measurements for reservoir characterization. In this last phase of the project we characterize a vuggy carbonate aquifer in the Hillsboro Basin, Palm Beach County, South Florida, using two data sets--the first generated by velocity tomography and the second generated by reflection tomography. First, we integrate optical macroscopic (OM), scanning electron microscope (SEM) and x-ray computed tomography (CT) images, as well as petrography, as a first step in characterizing the aquifer pore system. This pore scale integration provides information with which to evaluate nuclear magnetic resonance (NMR) well log signatures for NMR well log calibration, interpret ultrasonic data, and characterize flow units at the field scale between two wells in the aquifer. Saturated and desaturated NMR core measurements estimate the irreducible water in the rock and the variable T{sub 2} cut-offs for the NMR well log calibration. These measurements establish empirical equations to extract permeability from NMR well logs. Velocity and NMR-derived permeability and porosity relationships integrated with velocity tomography (based on crosswell seismic measurements recorded between two wells 100 m apart) capture two flow units that are supported with pore scale integration results. Next, we establish a more detailed picture of the complex aquifer pore structures and the critical role they play in water movement, which aids in our ability to characterize not only carbonate aquifers, but reservoirs in general. We analyze petrography and cores to reveal relationships between the rock physical properties that control the compressional and shear wave velocities of the formation. A digital thin section analysis provides the pore size distributions of the rock matrix, which allows us to relate pore structure to permeability and to characterize flow units at the

  10. Acoustic resonance scattering from a multilayered cylindrical shell with imperfect bonding.

    Rajabi, M; Hasheminejad, Seyyed M

    2009-12-01

    The method of wave function expansion is adopted to study the three dimensional scattering of a time-harmonic plane progressive sound field obliquely incident upon a multi-layered hollow cylinder with interlaminar bonding imperfection. For the generality of solution, each layer is assumed to be cylindrically orthotropic. An approximate laminate model in the context of the modal state equations with variable coefficients along with the classical T-matrix solution technique is set up for each layer to solve for the unknown modal scattering and transmission coefficients. A linear spring model is used to describe the interlaminar adhesive bonding whose effects are incorporated into the global transfer matrix by introduction of proper interfacial transfer matrices. Following the classic acoustic resonance scattering theory (RST), the scattered field and response to surface waves are determined by constructing the partial waves and obtaining the non-resonance (backgrounds) and resonance components. The solution is first used to investigate the effect of interlayer imperfection of an air-filled and water submerged bilaminate aluminium cylindrical shell on the resonances associated with various modes of wave propagation (i.e., symmetric/asymmetric Lamb waves, fluid-borne A-type waves, Rayleigh and Whispering Gallery waves) appearing in the backscattered spectrum, according to their polarization and state of stress. An illustrative numerical example is also given for a multi-layered (five-layered) cylindrical shell for which the stiffness of the adhesive interlayers is artificially varied. The sensitivity of resonance frequencies associated with higher mode numbers to the stiffness coefficients is demonstrated to be a good measure of the bonding strength. Limiting cases are considered and fair agreements with solutions available in the literature are established. PMID:19586650

  11. SiDIVS: Simple Detection of Inductive Vehicle Signatures with a Multiplex Resonant Sensor

    José J. Lamas-Seco

    2016-08-01

    Full Text Available This work provides a system capable of obtaining simultaneous inductive signatures of vehicles traveling on a roadway with minimal cost. Based on Time-Division Multiplexing (TDM with multiple oscillators, one for each inductive loop, the proposed system detects the presence of vehicles by means of a shift in the oscillation period of the selected loop and registers the signature of the detected vehicles by measuring the duration of a fixed number of oscillator pulses. In order to test the system in an actual environment, we implement a prototype that we denote as SiDIVS (Simple Detection of Inductive Vehicle Signatures and acquire different vehicle inductive signatures under real scenarios. We also test the robustness of the detector by simulating the effect of noise on the signature acquisition.

  12. SiDIVS: Simple Detection of Inductive Vehicle Signatures with a Multiplex Resonant Sensor.

    Lamas-Seco, José J; Castro, Paula M; Dapena, Adriana; Vazquez-Araujo, Francisco J

    2016-01-01

    This work provides a system capable of obtaining simultaneous inductive signatures of vehicles traveling on a roadway with minimal cost. Based on Time-Division Multiplexing (TDM) with multiple oscillators, one for each inductive loop, the proposed system detects the presence of vehicles by means of a shift in the oscillation period of the selected loop and registers the signature of the detected vehicles by measuring the duration of a fixed number of oscillator pulses. In order to test the system in an actual environment, we implement a prototype that we denote as SiDIVS (Simple Detection of Inductive Vehicle Signatures) and acquire different vehicle inductive signatures under real scenarios. We also test the robustness of the detector by simulating the effect of noise on the signature acquisition. PMID:27548167

  13. Acoustics

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  14. Mass Sensitivity Optimization of a Surface Acoustic Wave Sensor Incorporating a Resonator Configuration

    Hao, Wenchang; Liu, Jiuling; Liu, Minghua; Liang, Yong; He, Shitang

    2016-01-01

    The effect of the sensitive area of the two-port resonator configuration on the mass sensitivity of a Rayleigh surface acoustic wave (R-SAW) sensor was investigated theoretically, and verified in experiments. A theoretical model utilizing a 3-dimensional finite element method (FEM) approach was established to extract the coupling-of-modes (COM) parameters in the absence and presence of mass loading covering the electrode structures. The COM model was used to simulate the frequency response of an R-SAW resonator by a P-matrix cascading technique. Cascading the P-matrixes of unloaded areas with mass loaded areas, the sensitivity for different sensitive areas was obtained by analyzing the frequency shift. The performance of the sensitivity analysis was confirmed by the measured responses from the silicon dioxide (SiO2) deposited on different sensitive areas of R-SAW resonators. It is shown that the mass sensitivity varies strongly for different sensitive areas, and the optimal sensitive area lies towards the center of the device. PMID:27104540

  15. Optimization of Capacitive Acoustic Resonant Sensor Using Numerical Simulation and Design of Experiment

    Rubaiyet Iftekharul Haque

    2015-04-01

    Full Text Available Optimization of the acoustic resonant sensor requires a clear understanding of how the output responses of the sensor are affected by the variation of different factors. During this work, output responses of a capacitive acoustic transducer, such as membrane displacement, quality factor, and capacitance variation, are considered to evaluate the sensor design. The six device parameters taken into consideration are membrane radius, backplate radius, cavity height, air gap, membrane tension, and membrane thickness. The effects of factors on the output responses of the transducer are investigated using an integrated methodology that combines numerical simulation and design of experiments (DOE. A series of numerical experiments are conducted to obtain output responses for different combinations of device parameters using finite element methods (FEM. Response surface method is used to identify the significant factors and to develop the empirical models for the output responses. Finally, these results are utilized to calculate the optimum device parameters using multi-criteria optimization with desirability function. Thereafter, the validating experiments are designed and deployed using the numerical simulation to crosscheck the responses.

  16. Optimization of capacitive acoustic resonant sensor using numerical simulation and design of experiment.

    Haque, Rubaiyet Iftekharul; Loussert, Christophe; Sergent, Michelle; Benaben, Patrick; Boddaert, Xavier

    2015-01-01

    Optimization of the acoustic resonant sensor requires a clear understanding of how the output responses of the sensor are affected by the variation of different factors. During this work, output responses of a capacitive acoustic transducer, such as membrane displacement, quality factor, and capacitance variation, are considered to evaluate the sensor design. The six device parameters taken into consideration are membrane radius, backplate radius, cavity height, air gap, membrane tension, and membrane thickness. The effects of factors on the output responses of the transducer are investigated using an integrated methodology that combines numerical simulation and design of experiments (DOE). A series of numerical experiments are conducted to obtain output responses for different combinations of device parameters using finite element methods (FEM). Response surface method is used to identify the significant factors and to develop the empirical models for the output responses. Finally, these results are utilized to calculate the optimum device parameters using multi-criteria optimization with desirability function. Thereafter, the validating experiments are designed and deployed using the numerical simulation to crosscheck the responses. PMID:25894937

  17. Influence of bottom shape in the pipe wall thinning inspection using an electromagnetic acoustic resonance method

    Electromagnetic acoustic transducer (EMAT) provides non-contacting measurements and is often applied to monitoring in high temperature environment. Electromagnetic acoustic resonance method (EMAR) is transmits an ultrasonic burst wave, and the driving frequency of bust wave is swept. Then signal amplitude of each frequency is computed by the superheterodyne processing at the interval. Pulse-EMAR method is transmits an ultrasonic pulse wave propagating, but the pulse wave is not swept. Then echo waves received is analyzed by Fast Fourier Transform. Finally, the superposition of the nth compression (SNC) for data processing is applied to evaluate wall thickness for two methods, In this study, the influence of bottom shapes is evaluated using EMAR method and Pulse-EMAR method. And therefore the specimens of three types which are with inclined bottom, R shape and scale-like shape are prepared. Influence of bottom shape appears as an attenuating of peak value of SNC, a widening of the full width at half maximum, and peaks of multiple. (author)

  18. Evaluation of magnetic resonance imaging (MRI) in diagnosis of acoustic neuroma. Comparative study with plain X-ray and CTs

    Nomura, Kimihisa; Sakai, Makoto; Shinkawa, Atsushi; Miyake, Hirosato; Matsukawa, Junichi

    1987-11-01

    In order to find an approach to earlier and more acurate diagnosis of acoustic neuroma, a comparative evaluation of MRI, plain X-ray (Stenvers' projection), high resolution CT with or without Metrizamide enhancement and air-CT has been made in five clinical cases of acoustic neuroma. A paramagnetic contrast agent, Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA), was used to enhance images resolution in two cases of acoustic neuroma. In MRI, the high singnal mass in the posterior fossa was smaller than 10 x 10 mm in 2 cases, 17 x 20 mm in 2 cases and 35 x 40 mm in one case. MRI revealed enlargement of the neurovascular bundle around the VII and VIII cranial nerves compatible with a diagnosis of acoustic neuroma in all 5 cases, and masses within the cerebellopontine angle were also disclosed. In 2 cases the image of equivocal acoustic neuromas was well enhanced, and these lesions were visualized after intravenous administration of Gd-DTPA. In one of the cases the acoustic neuroma was satisfactorily differentiated from the surrounding cystic lesion with the aid of a contrast medium. Magnetic resonance which uses no ionizing radiation seems to be innocuous and offers several advantages over other imaging methods and CT, which may produce an adverse reaction when a contrast medium is used in CT-cisternography. Further advancement of MR technology will offer greater assistance in differential diagnosis of lesions such as acoustic tumors or other cerebellopontine angle tumors.

  19. The mass load effect on the resonant acoustic frequencies of colloidal semiconductor nanoplatelets

    Girard, Adrien; Saviot, Lucien; Pedetti, Silvia; Tessier, Mickaël D.; Margueritat, Jérémie; Gehan, Hélène; Mahler, Benoit; Dubertret, Benoit; Mermet, Alain

    2016-07-01

    Resonant acoustic modes of ultrathin CdS and CdSe colloidal nanoplatelets (NPLs) with varying thicknesses were probed using low frequency Raman scattering. The spectra are dominated by an intense band ascribed to the thickness breathing mode of the 2D nanostructures. The measured Raman frequencies show strong deviations with respect to the values expected for simple bare plates, all the more so as the thickness is reduced. The deviation is shown to arise from the additional mass of the organic ligands that are bound to the free surfaces of the nanoplatelets. The calculated eigen frequencies of vibrating platelets weighed down by the mass of the organic ligands are in very good agreement with the observed experimental behaviours. This finding opens up a new possibility of nanomechanical sensing such as nanobalances.Resonant acoustic modes of ultrathin CdS and CdSe colloidal nanoplatelets (NPLs) with varying thicknesses were probed using low frequency Raman scattering. The spectra are dominated by an intense band ascribed to the thickness breathing mode of the 2D nanostructures. The measured Raman frequencies show strong deviations with respect to the values expected for simple bare plates, all the more so as the thickness is reduced. The deviation is shown to arise from the additional mass of the organic ligands that are bound to the free surfaces of the nanoplatelets. The calculated eigen frequencies of vibrating platelets weighed down by the mass of the organic ligands are in very good agreement with the observed experimental behaviours. This finding opens up a new possibility of nanomechanical sensing such as nanobalances. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR07383A

  20. Material and device properties of ZnO-based film bulk acoustic resonator for mass sensing applications

    Zinc oxide based film bulk acoustic resonator as mass sensor was fabricated by multi-target magnetron sputtering under optimized deposition condition. Each layer of the device was well crystallized and highly textural observed by transmission electron microscopy and X-ray diffraction measurement. Through piezoelectric test, the device vibrated with significant distance. The influence of top electrode on resonant frequency and the bio-specimen of mass loading effect were investigated. Data show that the device has qualified properties as mass biosensor, with a resonant frequency of 3-4 GHz and a high sensitivity of 8-10 kHz cm2/ng

  1. The Glashow resonance at IceCube: signatures, event rates and pp vs. pγ interactions

    We revisit the signatures of the Glashow resonance process ν-bar ee → W in the high-energy astrophysical neutrino observatory IceCube. We note that in addition to the standard hadronic and electromagnetic showers produced by an incoming neutrino at the resonance energy of Eν ≈ 6.3 PeV, there are two clear signals of the process: the 'pure muon' from ν-bar ee → ν-bar μμ and the 'contained lollipop' from ν-bar ee → ν-bar ττ. The event rate and the signal-to-background ratio (the ratio of the resonant to concurrent non-resonant processes) are calculated for each type of interaction, based on current flux limits on the diffuse neutrino flux. Because of the low background in the neighborhood of the resonance, the observation of only one pure muon or contained lollipop event essentially signals discovery of the resonance, even if the expected event numbers are small. We also evaluate the total event rates of the Glashow resonance from the extra-galactic diffuse neutrino flux and emphasize its utility as a discovery tool to enable first observations of such a flux. We find that one can expect 3.6 (0.65) events per year for a pure pp (pγ) source, along with an added contribution of 0.51 (0.21) from non-resonant events. We also give results as a function of the ratio of pp vs pγ sources

  2. A poly(vinylidene fluoride)-coated ZnO film bulk acoustic resonator for nerve gas detection

    We apply the film bulk acoustic resonator for the detection of nerve gas. The resonator is consisted of a ZnO piezoelectric stack and a W/SiO2 Bragg reflector. Poly(vinylidene fluoride) (PVDF) is used as the sensing coating to adsorb the analyte under test. The testing results show that our proposed sensor can yield a sensitive, reversible and reproducible response to nerve gas. The relationship between the frequency shifts and the concentrations of the nerve gas exhibits a perfect linear correlation in the range of 10–50 ppm. The gas sensitivity of the proposed sensor is 718 kHz ppm−1, which is several orders of magnitude higher than that of a quartz crystal microbalance with the same sensitive coating. This study proves that it is feasible to use the PVDF-coated thin film bulk acoustic resonator for the detection of the traced nerve gas

  3. Kiwi fruit (Actinidia chinensis) quality determination based on surface acoustic wave resonator combined with electronic nose.

    Wei, Liu; Guohua, Hui

    2015-01-01

    In this study, electronic nose (EN) combined with a 433 MHz surface acoustic wave resonator (SAWR) was used to determine Kiwi fruit quality under 12-day storage. EN responses to Kiwi samples were measured and analyzed by principal component analysis (PCA) and stochastic resonance (SR) methods. SAWR frequency eigen values were also measured to predict freshness. Kiwi fruit sample's weight loss index and human sensory evaluation were examined to characteristic its quality and freshness. Kiwi fruit's quality predictive models based on EN, SAWR, and EN combined with SAWR were developed, respectively. Weight loss and human sensory evaluation results demonstrated that Kiwi fruit's quality decline and overall acceptance decrease during the storage. Experiment result indicated that the PCA method could qualitatively discriminate all Kiwi fruit samples with different storage time. Both SR and SAWR frequency analysis methods could successfully discriminate samples with high regression coefficients (R = 0.98093 and R = 0.99014, respectively). The validation experiment results showed that the mixed predictive model developed using EN combined with SAWR present higher quality prediction accuracy than the model developed either by EN or by SAWR. This method exhibits some advantages including high accuracy, non-destructive, low cost, etc. It provides an effective way for fruit quality rapid analysis. PMID:25551334

  4. Experimental study on acoustic subwavelength imaging of holey-structured metamaterials by resonant tunneling.

    Su, Haijing; Zhou, Xiaoming; Xu, Xianchen; Hu, Gengkai

    2014-04-01

    A holey-structured metamaterial is proposed for near-field acoustic imaging beyond the diffraction limit. The structured lens consists of a rigid slab perforated with an array of cylindrical holes with periodically modulated diameters. Based on the effective medium approach, the structured lens is characterized by multilayered metamaterials with anisotropic dynamic mass, and an analytic model is proposed to evaluate the transmission properties of incident evanescent waves. The condition is derived for the resonant tunneling, by which evanescent waves can completely transmit through the structured lens without decaying. As an advantage of the proposed lens, the imaging frequency can be modified by the diameter modulation of internal holes without the change of the lens thickness in contrast to the lens due to the Fabry-Pérot resonant mechanism. In this experiment, the lens is assembled by aluminum plates drilled with cylindrical holes. The imaging experiment demonstrates that the designed lens can clearly distinguish two sources separated in the distance below the diffraction limit at the tunneling frequency. PMID:25234968

  5. Detecting leaks in gas-filled pressure vessels using acoustic resonances

    Gillis, K. A.; Moldover, M. R.; Mehl, J. B.

    2016-05-01

    We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f2 than by measuring the ratio p/T. Here f is the resonance frequency of an acoustic mode of the gas inside the pressure vessel, p is the pressure of the gas, and T is the kelvin temperature measured at one point in the gas. In general, the resonance frequencies are determined by a mode-dependent, weighted average of the square of the speed-of-sound throughout the volume of the gas. However, the weighting usually has a weak dependence on likely temperature gradients in the gas inside a large pressure vessel. Using the ratio p/f2, we measured a gas leak (dM/dt)/M ≈ - 1.3 × 10-5 h-1 = - 0.11 yr-1 from a 300-liter pressure vessel filled with argon at 450 kPa that was exposed to sunshine-driven temperature and pressure fluctuations as large as (dT/dt)/T ≈ (dp/dt)/p ≈ 5 × 10-2 h-1 using a 24-hour data record. This leak could not be detected in a 72-hour record of p/T. (Here M is the mass of the gas in the vessel and t is the time.)

  6. Resonant instability of the surface dust-acoustic wave in electron–positron–ion dusty plasmas including pair annihilation effects

    The influence of electron–positron pair annihilations on the resonant instability of surface dust-acoustic wave is investigated in semi-bounded electron–positron–ion dusty plasmas. The dispersion relation and the temporal growth rate of the surface dust-acoustic wave including the pair annihilation effect are obtained by the specular reflection boundary condition. It is found that the electron–positron annihilation effect suppresses the temporal growth rate of the surface dust-acoustic instability and, however, increases the domain of the resonant instability. It is also shown that the pair annihilation effect on the growth rate decreases with increasing wave number and dust plasma frequency. The variation of the domain and magnitude of temporal growth rate is also discussed. - Highlights: • The resonant instability of surface dust-acoustic wave is investigated in semi-bounded electron–positron pair dusty plasmas. • The dispersion relation and the temporal growth rate are obtained by the specular reflection boundary condition. • The pair annihilation effects on the domain and magnitude of temporal growth rate are discussed

  7. Perceptual identification and acoustic measures of the resonant voice based on "Lessac's Y-Buzz"--a preliminary study with actors.

    Barrichelo, Viviane M O; Behlau, Mara

    2007-01-01

    This study aimed to verify whether the resonant voice based on Lessac's Y-Buzz can be perceived by listeners as resonant and different from habitual voice and to compare them to determine whether this sound exploration improves the vocal production. Nine newly graduated actors, six men and three women without voice complaints, were the subjects. They received a session of Lessac's Y-Buzz training from the primary investigator. Before training, they were asked to sustain the vowel /i/ at comfortable frequency and habitual loudness. After training, they were requested to sustain the Y-Buzz they had learned at a comfortable frequency and habitual loudness. Three speech-language pathologists (SLP) trained in voice developed an auditory-perceptive analysis. The pre- and posttraining voice samples were randomly spliced together, edited, and presented in pairs to perceptual judges who were asked to identify the most resonant of the pair. The voice samples were also acoustically compared through the Hoarseness Diagram and acoustic measures using the VoxMetria Software (CTS, version 2.0s, Brazil). The Y-Buzz trials were identified as resonant voice in 74% of the comparisons. The acoustic measures showed a statistically significant decrease of irregularity (P = 0.002) and shimmer (P = 0.38). The Hoarseness Diagram demonstrated how the resonant voice moved toward the normality for irregularity and noise components. The results showed that the resonant voice based on the Y-Buzz can be identified as resonant and different from normal voicing in the same subject, and it apparently implies a better vocal production demonstrating a significant decrease of shimmer and irregularity through the Hoarseness Diagram evaluation. PMID:16458480

  8. Resonance Type Instabilities in the Gaseous Disks of the Flat Galaxies 1 The Acoustical Resonance Type Instability and the Absence of Vortex Sheet Stabilization on Shallow Water

    Mustsevaya, J V

    1998-01-01

    Linear analysis of vortex sheet stability in the rotating gaseous disk or shallow water layer shows that presence of a central reflecting surface changes system stability significantly. An effect of absence of vortex sheet stabilization has been found as compressibility exceeds Landau criterion. The properties of multimode short-scale instability of acoustical resonance type are investigated and probability of its influence upon experiments on the rotating shallow water is discussed.

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

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

  10. Particle mesh simulations of the Lyman-alpha forest and the signature of Baryon Acoustic Oscillations in the intergalactic medium

    White, Martin; Carlson, Jordan; Heitmann, Katrin; Habib, Salman; Fasel, Patricia; Daniel, David; Lukic, Zarija

    2009-01-01

    We present a set of ultra-large particle-mesh simulations of the LyA forest targeted at understanding the imprint of baryon acoustic oscillations (BAO) in the inter-galactic medium. We use 9 dark matter only simulations which can, for the first time, simultaneously resolve the Jeans scale of the intergalactic gas while covering the large volumes required to adequately sample the acoustic feature. Mock absorption spectra are generated using the fluctuating Gunn-Peterson approximation which have approximately correct flux probability density functions (PDFs) and small-scale power spectra. On larger scales there is clear evidence in the redshift space correlation function for an acoustic feature, which matches a linear theory template with constant bias. These spectra, which we make publicly available, can be used to test pipelines, plan future experiments and model various physical effects. As an illustration we discuss the basic properties of the acoustic signal in the forest, the scaling of errors with noise ...

  11. Focusing of the lowest-order antisymmetric Lamb mode behind a gradient-index acoustic metalens with local resonators

    Zhao, Jinfeng; Bonello, Bernard; Boyko, Olga

    2016-05-01

    We have investigated the focusing of the lowest-order antisymmetric Lamb mode (A0) behind a positive gradient-index (GRIN) acoustic metalens consisting of air holes drilled in a silicon plate with silicon pillars erected on one face of the lens. We have analyzed the focusing in the near field as the result of the coupling between the flexural resonant mode of the pillars and the vibration mode of the air/silicon phononic crystal. We highlight the role played by the polarization coherence between the resonant mode and the vibration of the plate. We demonstrate both numerically and experimentally the focusing behind the lens over a spot less than half a wavelength, paving a way for performance of acoustic lenses beyond the diffraction limit. Our findings can be easily extended to other types of elastic wave.

  12. A process to control light in a micro resonator through a coupling modulation by surface acoustic waves

    Fan, Guofang; Li, Yuan; Hu, Chunguang; Lei, Lihua; Guo, Yanchuan

    2016-08-01

    A novel process to control light through the coupling modulation by surface acoustic wave (SAW) is presented in an optical micro resonator. An optical waveguide modulator of a racetrack resonator on silicon-on-insulator (SOI) technology is took as an example to explore the mechanism. A finite-difference time-domain (FDTD) is developed to simulate the acousto-optical (AO) modulator using the mechanism. An analytical method is presented to verify our proposal. The results show that the process can work well as an optical modulator by SAW.

  13. The Liquid Sensor Using Thin Film Bulk Acoustic Resonator with C-Axis Tilted AlN Films

    Ying-Chung Chen; Wei-Tsai Chang; Kuo-Sheng Kao; Chun-Hung Yang; Chien-Chuan Cheng

    2013-01-01

    Dual-mode thin film bulk acoustic resonator (TFBAR) devices are fabricated with c-axis tilted AlN films. To fabricate dual-mode TFBAR devices, the off-axis RF magnetron sputtering method for the growth of tilted piezoelectric AlN thin films is adopted. In this report, the AlN thin films are deposited with tilting angles of 15° and 23°. The frequency response of the TFBAR device with 23° tilted AlN thin film is measured to reveal its ability to provide dual-mode resonance. The sensitivities of...

  14. Acoustic cloaking and transformation acoustics

    Chen Huanyang [School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu 215006 (China); Chan, C T, E-mail: kenyon@ust.h, E-mail: phchan@ust.h [Department of Physics and the William Mong Institute of NanoScience and Technology, The Hong Kong University of Science and Technology, Clear Water Bay (Hong Kong)

    2010-03-24

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

  15. Acoustic cloaking and transformation acoustics

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

  16. Analysis of the Nonlinear Structural-Acoustic Resonant Frequencies of a Rectangular Tube with a Flexible End Using Harmonic Balance and Homotopy Perturbation Methods

    Y. Y. Lee

    2012-01-01

    Full Text Available The structural acoustic problem considered in this study is the nonlinear resonant frequencies of a rectangular tube with one open end, one flexible end, and four rigid side walls A multiacoustic single structural modal formulation is derived from two coupled partial differential equations which represent the large amplitude structural vibration of the flexible end and acoustic pressure induced within the tube. The results obtained from the harmonic balance and homotopy perturbation approaches verified each other. The effects of vibration amplitude, aspect ratio, the numbers of acoustic modes and harmonic terms, and so forth, on the first two resonant natural frequencies, are examined.

  17. Diboson and di--photon resonances and other new physics signatures

    Martyniuk, Alex; The ATLAS collaboration

    2016-01-01

    The search for physics beyond the standard model restarted at the LHC last year at the new energy of 13TeV. The ATLAS and CMS general purpose detectors continue to use this data to push forwards into the energy frontier. Possible hints of new physics have been seen by both experiments in the diboson and di-photon resonance search channels. In this talk I will present the latest results of the searches for di-boson and di-photon resonances as well as other new physics signals from both detectors

  18. Effect of grazing flow on the acoustic impedance of Helmholtz resonators consisting of single and clustered orifices

    Hersch, A. S.; Walker, B.

    1979-01-01

    A semiempirical fluid mechanical model is derived for the acoustic behavior of thin-walled single orifice Helmholtz resonators in a grazing flow environment. The incident and cavity sound fields are connected in terms of an orifice discharge coefficient whose values are determined experimentally using the two-microphone method. Measurements show that at high grazing flow speeds, acoustical resistance is almost linearly proportional to the grazing flow speed and almost independent of incident sound pressure. The corresponding values of reactance are much smaller and tend towards zero. For thicker-walled orifice plates, resistance and reactance were observed to be less sensitive to grazing flow as the ratio of plate thickness to orifice diameter increased. Loud tones were observed to radiate from a single orifice Helmholtz resonator due to interaction between the grazing flow shear layer and the resonator cavity. Measurements showed that the tones radiated at a Strouhal number equal to 0.26. The effects of grazing flow on the impedance of Helmholtz resonators consisting of clusters of orifices was also studied. In general, both resistance and reaction were found to be virtually independent of orifice relative spacing and number. These findings are valid with and without grazing flow.

  19. Introducing passive acoustic filter in acoustic based condition monitoring: Motor bike piston-bore fault identification

    Jena, D. P.; Panigrahi, S. N.

    2016-03-01

    Requirement of designing a sophisticated digital band-pass filter in acoustic based condition monitoring has been eliminated by introducing a passive acoustic filter in the present work. So far, no one has attempted to explore the possibility of implementing passive acoustic filters in acoustic based condition monitoring as a pre-conditioner. In order to enhance the acoustic based condition monitoring, a passive acoustic band-pass filter has been designed and deployed. Towards achieving an efficient band-pass acoustic filter, a generalized design methodology has been proposed to design and optimize the desired acoustic filter using multiple filter components in series. An appropriate objective function has been identified for genetic algorithm (GA) based optimization technique with multiple design constraints. In addition, the sturdiness of the proposed method has been demonstrated in designing a band-pass filter by using an n-branch Quincke tube, a high pass filter and multiple Helmholtz resonators. The performance of the designed acoustic band-pass filter has been shown by investigating the piston-bore defect of a motor-bike using engine noise signature. On the introducing a passive acoustic filter in acoustic based condition monitoring reveals the enhancement in machine learning based fault identification practice significantly. This is also a first attempt of its own kind.

  20. Contactless transport of matter in the first five resonance modes of a line-focused acoustic manipulator.

    Foresti, Daniele; Nabavi, Majid; Poulikakos, Dimos

    2012-02-01

    The first five resonance modes for transport of matter in a line-focused acoustic levitation system are investigated. Contactless transport was achieved by varying the height between the radiating plate and the reflector. Transport and levitation of droplets in particular involve two limits of the acoustic forces. The lower limit corresponds to the minimum force required to overcome the gravitational force. The upper limit corresponds to the maximum acoustic pressure beyond which atomization of the droplet occurs. As the droplet size increases, the lower limit increases and the upper limit decreases. Therefore to have large droplets levitated, relatively flat radiation pressure amplitude during the translation is needed. In this study, using a finite element model, the Gor'kov potential was calculated for different heights between the reflector and the radiating plate. The application of the Gor'kov potential was extended to study the range of droplet sizes for which the droplets can be levitated and transported without atomization. It was found that the third resonant mode (H(3)-mode) represents the best compromise between high levitation force and smooth pattern transition, and water droplets of millimeter radius can be levitated and transported. The H(3)-mode also allows for three translation lines in parallel. PMID:22352478

  1. Acoustic resonance characteristics of the human vocal tract with respect to a soft tissue

    Radolf, Vojtěch; Horáček, Jaromír

    Praha: Ústav termomechaniky AV ČR, v. v. i., 2015 - (Zolotarev, I.; Pešek, L.), s. 55-58 ISBN 978-80-87012-57-4. [DYMAMESI 2015. Praha (CZ), 24.11.2015] Institutional support: RVO:61388998 Keywords : biomechanics of voice * acoustic-structural interaction * formant frequency * phonation into tubes Subject RIV: BI - Acoustics

  2. The Detectability of Exo-Earths and Super-Earths Via Resonant Signatures in Exozodiacal Clouds

    Stark, Christopher C

    2008-01-01

    Directly imaging extrasolar terrestrial planets necessarily means contending with the astrophysical noise of exozodiacal dust and the resonant structures created by these planets in exozodiacal clouds. Using a custom tailored hybrid symplectic integrator we have constructed 120 models of resonant structures created by exo-Earths and super-Earths on circular orbits interacting with collisionless steady-state dust clouds around a Sun-like star. Our models include enough particles to overcome the limitations of previous simulations that were often dominated by a handful of long-lived particles, allowing us to quantitatively study the contrast of the resulting ring structures. We found that in the case of a planet on a circular orbit, for a given star and dust source distribution, the morphology and contrast of the resonant structures depend on only two parameters: planet mass and $\\sqrt{a_{\\rm p}}/\\beta$, where $a_{\\rm p}$ is the planet's semi-major axis and $\\beta$ is the ratio of radiation pressure force to gr...

  3. Advanced numerical technique for analysis of surface and bulk acoustic waves in resonators using periodic metal gratings

    Naumenko, Natalya F.

    2014-09-01

    A numerical technique characterized by a unified approach for the analysis of different types of acoustic waves utilized in resonators in which a periodic metal grating is used for excitation and reflection of such waves is described. The combination of the Finite Element Method analysis of the electrode domain with the Spectral Domain Analysis (SDA) applied to the adjacent upper and lower semi-infinite regions, which may be multilayered and include air as a special case of a dielectric material, enables rigorous simulation of the admittance in resonators using surface acoustic waves, Love waves, plate modes including Lamb waves, Stonely waves, and other waves propagating along the interface between two media, and waves with transient structure between the mentioned types. The matrix formalism with improved convergence incorporated into SDA provides fast and robust simulation for multilayered structures with arbitrary thickness of each layer. The described technique is illustrated by a few examples of its application to various combinations of LiNbO3, isotropic silicon dioxide and silicon with a periodic array of Cu electrodes. The wave characteristics extracted from the admittance functions change continuously with the variation of the film and plate thicknesses over wide ranges, even when the wave nature changes. The transformation of the wave nature with the variation of the layer thicknesses is illustrated by diagrams and contour plots of the displacements calculated at resonant frequencies.

  4. A rapid magnetic resonance acoustic radiation force imaging sequence for ultrasonic refocusing.

    Mougenot, Charles; Pichardo, Samuel; Engler, Steven; Waspe, Adam; Colas, Elodie Constanciel; Drake, James M

    2016-08-01

    Magnetic resonance guided acoustic radiation force imaging (MR-ARFI) is being used to correct for aberrations induced by tissue heterogeneities when using high intensity focusing ultrasound (HIFU). A compromise between published MR-ARFI adaptive solutions is proposed to achieve efficient refocusing of the ultrasound beam in under 10 min. In addition, an ARFI sequence based on an EPI gradient echo sequence was used to simultaneously monitor displacement and temperature with a large SNR and low distortion. This study was conducted inside an Achieva 3T clinical MRI using a Philips Sonalleve MR-HIFU system to emit a 1 ms pulsed sonication with duty cycle of 2.3% at 300 Wac inside a polymer phantom. Virtual elements defined by a Hadamard array with sonication patterns composed of 6 phase steps were used to characterize 64 groups of 4 elements to find the optimal phase of the 256 elements of the transducer. The 384 sonication patterns were acquired in 580 s to identify the set of phases that maximize the displacement at the focal point. Three aberrators (neonatal skull, 8 year old skull and a checkered pattern) were added to each sonication pattern to evaluate the performance of this refocusing algorithm (n  =  4). These aberrators reduced the relative intensities to 95.3%, 69.6% and 25.5% for the neonatal skull, 8 year old skull, and checkered pattern virtual aberrators respectively. Using a 10 min refocusing algorithm, relative intensities of 101.6%, 91.3% and 93.3% were obtained. Better relative intensities of 103.9%, 94.3% and 101% were achieved using a 25 min refocusing algorithm. An average temperature increase of 4.2 °C per refocusing test was induced for the 10 min refocusing algorithm, resulting in a negligible thermal dose of 2 EM. A rapid refocusing of the beam can be achieved while keeping thermal effects to a minimum. PMID:27401452

  5. A rapid magnetic resonance acoustic radiation force imaging sequence for ultrasonic refocusing

    Mougenot, Charles; Pichardo, Samuel; Engler, Steven; Waspe, Adam; Constanciel Colas, Elodie; Drake, James M.

    2016-08-01

    Magnetic resonance guided acoustic radiation force imaging (MR-ARFI) is being used to correct for aberrations induced by tissue heterogeneities when using high intensity focusing ultrasound (HIFU). A compromise between published MR-ARFI adaptive solutions is proposed to achieve efficient refocusing of the ultrasound beam in under 10 min. In addition, an ARFI sequence based on an EPI gradient echo sequence was used to simultaneously monitor displacement and temperature with a large SNR and low distortion. This study was conducted inside an Achieva 3T clinical MRI using a Philips Sonalleve MR-HIFU system to emit a 1 ms pulsed sonication with duty cycle of 2.3% at 300 Wac inside a polymer phantom. Virtual elements defined by a Hadamard array with sonication patterns composed of 6 phase steps were used to characterize 64 groups of 4 elements to find the optimal phase of the 256 elements of the transducer. The 384 sonication patterns were acquired in 580 s to identify the set of phases that maximize the displacement at the focal point. Three aberrators (neonatal skull, 8 year old skull and a checkered pattern) were added to each sonication pattern to evaluate the performance of this refocusing algorithm (n  =  4). These aberrators reduced the relative intensities to 95.3%, 69.6% and 25.5% for the neonatal skull, 8 year old skull, and checkered pattern virtual aberrators respectively. Using a 10 min refocusing algorithm, relative intensities of 101.6%, 91.3% and 93.3% were obtained. Better relative intensities of 103.9%, 94.3% and 101% were achieved using a 25 min refocusing algorithm. An average temperature increase of 4.2 °C per refocusing test was induced for the 10 min refocusing algorithm, resulting in a negligible thermal dose of 2 EM. A rapid refocusing of the beam can be achieved while keeping thermal effects to a minimum.

  6. Constraint on the growth factor of the cosmic structure from the damping of the baryon acoustic oscillation signature

    Nakamura, Gen; Huetsi, Gert; Sato, Takahiro; Yamamoto, Kazuhiro

    2009-01-01

    We determine a constraint on the growth factor by measuring the damping of the baryon acoustic oscillations in the matter power spectrum using the Sloan Digital Sky Survey luminous red galaxy sample. The damping of the BAO is detected at the one sigma level. We obtain \\sigma_8D_1(z=0.3) = 0.42^{+0.34}_{-0.28} at the 1\\sigma statistical level, where \\sigma_8 is the root mean square overdensity in a sphere of radius 8h^{-1}Mpc and D_1(z) is the growth factor at redshift z. The above result assu...

  7. The possibilities of tuning and optimisation of acoustic resonance properties of the human vocal tract

    Radolf, Vojtěch; Vampola, T.

    Praha: Institute of Thermomechanics AS CR, v. v. i., 2007 - (Zolotarev, I.), s. 237-238 ISBN 978-80-87012-06-2. [Engineering Mechanics 2007: national conference with international participation. Svratka (CZ), 14.05.2007-17.05.2007] R&D Projects: GA ČR GA106/04/1025 Institutional research plan: CEZ:AV0Z20760514 Keywords : acoustics * optimisation * formant tuning Subject RIV: BI - Acoustics

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

    Tadesse, Semere Ayalew; Li, Mo

    2014-01-01

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

  9. Serum metabolic signature of minimal hepatic encephalopathy by (1)H-nuclear magnetic resonance.

    Jiménez, Beatriz; Montoliu, Carmina; MacIntyre, David A; Serra, Miguel A; Wassel, Abdallah; Jover, María; Romero-Gomez, Manuel; Rodrigo, Jose M; Pineda-Lucena, Antonio; Felipo, Vicente

    2010-10-01

    Minimal hepatic encephalopathy (MHE) reduces quality of life of cirrhotic patients, predicts overt hepatic encephalopathy, and is associated with poor prognosis. We hypothesized that MHE arises once metabolic alterations derived from the liver reach a particular threshold. Our aim was to assess whether metabolic profiling of serum samples by high-field (1)H-nuclear magnetic resonance spectroscopy ((1)H NMR) and subsequent multivariate analyses would be useful to characterize metabolic perturbations associated with MHE and to identify potential metabolic biomarkers. Metabolic serum profiles from controls (n = 69) and cirrhotic patients without MHE (n = 62) and with MHE (n = 39) were acquired using high field NMR. Supervised modeling of the data provided perfect discrimination between healthy controls and cirrhotic patients and allowed the generation of a predictive model displaying strong discrimination between patients with and without MHE (R(2)Y = 0.68, Q(2)Y = 0.63). MHE patients displayed increased serum concentrations of glucose, lactate, methionine, TMAO, and glycerol, as well as decreased levels of choline, branch amino acids, alanine, glycine, acetoacetate, NAC, and lipid moieties. Serum metabonomics by (1)H NMR offers a useful approach for characterizing underlying metabolic differences between patients with and without MHE. This procedure shows great potential as a diagnostic tool of MHE as it objectively reflects measurable biochemical differences between the patient groups and may facilitate monitoring of both disease progression and effects of therapeutic treatments. PMID:20690770

  10. Different molecular signatures in magnetic resonance imaging-staged facioscapulohumeral muscular dystrophy muscles.

    Giorgio Tasca

    Full Text Available BACKGROUND: Facioscapulohumeral muscular dystrophy (FSHD is one of the most common muscular dystrophies and is characterized by a non-conventional genetic mechanism activated by pathogenic D4Z4 repeat contractions. By muscle Magnetic Resonance Imaging (MRI we observed that T2-short tau inversion recovery (T2-STIR sequences identify two different conditions in which each muscle can be found before the irreversible dystrophic alteration, marked as T1-weighted sequence hyperintensity, takes place. We studied these conditions in order to obtain further information on the molecular mechanisms involved in the selective wasting of single muscles or muscle groups in this disease. METHODS: Histopathology, gene expression profiling and real time PCR were performed on biopsies from FSHD muscles with different MRI pattern (T1-weighted normal/T2-STIR normal and T1-weighted normal/T2-STIR hyperintense. Data were compared with those from inflammatory myopathies, dysferlinopathies and normal controls. In order to validate obtained results, two additional FSHD samples with different MRI pattern were analyzed. RESULTS: Myopathic and inflammatory changes characterized T2-STIR hyperintense FSHD muscles, at variance with T2-STIR normal muscles. These two states could be easily distinguished from each other by their transcriptional profile. The comparison between T2-STIR hyperintense FSHD muscles and inflammatory myopathy muscles showed peculiar changes, although many alterations were shared among these conditions. CONCLUSIONS: At the single muscle level, different stages of the disease correspond to the two MRI patterns. T2-STIR hyperintense FSHD muscles are more similar to inflammatory myopathies than to T2-STIR normal FSHD muscles or other muscular dystrophies, and share with them upregulation of genes involved in innate and adaptive immunity. Our data suggest that selective inflammation, together with perturbation in biological processes such as neoangiogenesis

  11. A Methodology to Integrate Magnetic Resonance and Acoustic Measurements for Reservoir Characterization

    Parra, Jorge O.; Hackert, Chris L.; Collier, Hughbert A.; Bennett, Michael

    2002-01-29

    The objective of this project was to develop an advanced imaging method, including pore scale imaging, to integrate NMR techniques and acoustic measurements to improve predictability of the pay zone in hydrocarbon reservoirs. This is accomplished by extracting the fluid property parameters using NMR laboratory measurements and the elastic parameters of the rock matrix from acoustic measurements to create poroelastic models of different parts of the reservoir. Laboratory measurement techniques and core imaging are being linked with a balanced petrographical analysis of the core and theoretical model.

  12. Sensitivity of Acoustic Resonance Properties to a Change in Volume of Piriform Sinuses

    Radolf, Vojtěch

    2016-01-01

    Roč. 821, č. 2016 (2016), s. 671-676. ISSN 1662-7482 R&D Projects: GA ČR GPP101/12/P579 Institutional support: RVO:61388998 Keywords : piriform sinus * vocal tract model * biomechanics of voice * formant frequency Subject RIV: BI - Acoustics

  13. Sensitivity of Acoustic Resonance Properties to a Change in Volume of Piriform Sinuses

    Radolf, Vojtěch

    2016-01-01

    Roč. 821, č. 2016 (2016), s. 671-676. ISSN 1660-9336 R&D Projects: GA ČR GAP101/12/P579 Institutional support: RVO:61388998 Keywords : piriform sinus * vocal tract model * biomechanics of voice * formant frequency Subject RIV: BI - Acoustics

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

    Farrell, W E; Munk, Walter

    2013-10-01

    In 1999, Duennebier et al. deployed a hydrophone and geophone below the conjugate depth in the abyssal Pacific, midway between Hawaii and California. Real time data were transmitted for 3 yr over an abandoned ATT cable. These data have been analyzed in the frequency band 1 to 30 Hz. Between 1 and 6 Hz, the bottom data are interpreted as acoustic radiation from surface gravity waves, an extension to higher frequencies of a non-linear mechanism proposed by Longuet-Higgins in 1950 to explain microseisms. The inferred surface wave spectrum for wave lengths between 6 m and 17 cm is saturated (wind-independent) and roughly consistent with the traditional Phillips κ(-4) wave number spectrum. Shorter ocean waves have a strong wind dependence and a less steep wave number dependence. Similar features are found in the bottom record between 6 and 30 Hz. But this leads to an enigma: The derived surface spectrum inferred from the Longuet-Higgins mechanism with conventional assumptions for the dispersion relation is associated with mean square slopes that greatly exceed those derived from glitter. Regardless of the generation mechanism, the measured bottom intensities between 10 and 30 Hz are well below minimum noise standards reported in the literature. PMID:24116511

  15. Signatures of the Primordial Universe from Its Emptiness: Measurement of Baryon Acoustic Oscillations from Minima of the Density Field

    Kitaura, Francisco-Shu; Chuang, Chia-Hsun; Liang, Yu; Zhao, Cheng; Tao, Charling; Rodríguez-Torres, Sergio; Eisenstein, Daniel J.; Gil-Marín, Héctor; Kneib, Jean-Paul; McBride, Cameron; Percival, Will J.; Ross, Ashley J.; Sánchez, Ariel G.; Tinker, Jeremy; Tojeiro, Rita; Vargas-Magana, Mariana; Zhao, Gong-Bo

    2016-04-01

    Sound waves from the primordial fluctuations of the Universe imprinted in the large-scale structure, called baryon acoustic oscillations (BAOs), can be used as standard rulers to measure the scale of the Universe. These oscillations have already been detected in the distribution of galaxies. Here we propose to measure BAOs from the troughs (minima) of the density field. Based on two sets of accurate mock halo catalogues with and without BAOs in the seed initial conditions, we demonstrate that the BAO signal cannot be obtained from the clustering of classical disjoint voids, but it is clearly detected from overlapping voids. The latter represent an estimate of all troughs of the density field. We compute them from the empty circumsphere centers constrained by tetrahedra of galaxies using Delaunay triangulation. Our theoretical models based on an unprecedented large set of detailed simulated void catalogues are remarkably well confirmed by observational data. We use the largest recently publicly available sample of luminous red galaxies from SDSS-III BOSS DR11 to unveil for the first time a >3 σ BAO detection from voids in observations. Since voids are nearly isotropically expanding regions, their centers represent the most quiet places in the Universe, keeping in mind the cosmos origin and providing a new promising window in the analysis of the cosmological large-scale structure from galaxy surveys.

  16. Characterizing riverbed sediment using high-frequency acoustics 2: scattering signatures of Colorado River bed sediment in Marble and Grand Canyons

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

    2014-01-01

    In this, the second of a pair of papers on the statistical signatures of riverbed sediment in high-frequency acoustic backscatter, spatially explicit maps of the stochastic geometries (length- and amplitude-scales) of backscatter are related to patches of riverbed surfaces composed of known sediment types, as determined by geo-referenced underwater video observations. Statistics of backscatter magnitudes alone are found to be poor discriminators between sediment types. However, the variance of the power spectrum, and the intercept and slope from a power-law spectral form (termed the spectral strength and exponent, respectively) successfully discriminate between sediment types. A decision-tree approach was able to classify spatially heterogeneous patches of homogeneous sands, gravels (and sand-gravel mixtures), and cobbles/boulders with 95, 88, and 91% accuracy, respectively. Application to sites outside the calibration, and surveys made at calibration sites at different times, were plausible based on observations from underwater video. Analysis of decision trees built with different training data sets suggested that the spectral exponent was consistently the most important variable in the classification. In the absence of theory concerning how spatially variable sediment surfaces scatter high-frequency sound, the primary advantage of this data-driven approach to classify bed sediment over alternatives is that spectral methods have well understood properties and make no assumptions about the distributional form of the fluctuating component of backscatter over small spatial scales.

  17. Split Hopkinson Resonant Bar Test for Sonic-Frequency Acoustic Velocity and Attenuation Measurements of Small, Isotropic Geologic Samples

    Nakagawa, S.

    2011-04-01

    Mechanical properties (seismic velocities and attenuation) of geological materials are often frequency dependent, which necessitates measurements of the properties at frequencies relevant to a problem at hand. Conventional acoustic resonant bar tests allow measuring seismic properties of rocks and sediments at sonic frequencies (several kilohertz) that are close to the frequencies employed for geophysical exploration of oil and gas resources. However, the tests require a long, slender sample, which is often difficult to obtain from the deep subsurface or from weak and fractured geological formations. In this paper, an alternative measurement technique to conventional resonant bar tests is presented. This technique uses only a small, jacketed rock or sediment core sample mediating a pair of long, metal extension bars with attached seismic source and receiver - the same geometry as the split Hopkinson pressure bar test for large-strain, dynamic impact experiments. Because of the length and mass added to the sample, the resonance frequency of the entire system can be lowered significantly, compared to the sample alone. The experiment can be conducted under elevated confining pressures up to tens of MPa and temperatures above 100 C, and concurrently with x-ray CT imaging. The described Split Hopkinson Resonant Bar (SHRB) test is applied in two steps. First, extension and torsion-mode resonance frequencies and attenuation of the entire system are measured. Next, numerical inversions for the complex Young's and shear moduli of the sample are performed. One particularly important step is the correction of the inverted Young's moduli for the effect of sample-rod interfaces. Examples of the application are given for homogeneous, isotropic polymer samples and a natural rock sample.

  18. Design of tunable acoustic metamaterials through periodic arrays of resonant shunted piezos

    Periodic shunted piezoelectric patches are employed for the design of a tunable, one-dimensional metamaterial. The configuration considered encompasses a beam undergoing longitudinal and transverse motion, and a periodic array of piezoelectric patches with electrodes connected to a resonant electric circuit. The resulting acousto-electrical system is characterized by an internal resonant behavior that occurs at the tuning frequency of the shunting circuits, and is analogous in its operation to other internally resonating systems previously proposed, with the addition of its simple tunability. The performance of the beam is characterized through the application of the transfer matrix approach, which evaluates the occurrence of bandgaps at the tuning frequencies and estimates wave attenuation within such bands. Moreover, a homogenization study is conducted to illustrate the internal resonant characteristics of the system within an analytical framework. Experiments performed on the considered beam structure validate the theoretical predictions and illustrate its internal resonant characteristics and the formation of the related bandgaps. (paper)

  19. Tracking and understanding the acoustic signature of fluido-fractures: a dual optical/micro-seismic study

    Turkaya, Semih; Toussaint, Renaud; Kvalheim Eriksen, Fredrik; Zecevic, Megan; Daniel, Guillaume; Jørgen Måløy, Knut; Grude Flekkøy, Eirik

    2015-04-01

    The characterization and comprehension of irreversible rock deformation processes due to fluid flow is a challenging problem with numerous applications in many fields. This phenomenon has received an ever-increasing attention in Earth Science, Physics, with many applications in natural hazard understanding, mitigation or forecast (e.g. earthquakes, control the mechanical stability of rock and soil formations during the injection or extraction of fluids, landslides with hydrological control, volcanic eruptions), or in the industry, as CO2 sequestration. In this study, analogue models are developed (similar to the previous work of Johnsen[1] but in rectangular shape) to study the instabilities developing during motion of fluid in dense porous materials: fracturing, fingering, channelling… We study these complex fluid/solid mechanical systems using two imaging techniques: fast optical imaging and high frequency resolution of acoustic emissions. Additionally, we develop physical models rendering for the fluid mechanics (similar to the work of Niebling[2] but with injection of fluid) in the channels and the propagation of microseismic waves around the fracture. We then confront a numerical resolution of this physical system with the observed experimental system. The experimental setup consists in a rectangular Hele-Shaw cell with three closed boundaries and one semi-permeable boundary which enables the flow of the fluid but not the solid particles. During the experiments, the fluid is injected into the system with a constant injection pressure from the point opposite to the semi-permeable boundary. The fluid penetrates into the solid using the pore network. At the large enough injection pressures, the fluid also makes its way via creating channels, fractures to the semi-permeable boundary. During the experiments acoustic signals are recorded using different sensors then, those signals are compared and investigated further in both time and frequency domains

  20. Optimization of Encoding Gradients for Magnetic Resonance Acoustic Radiation Force Imaging

    Chen, Jing; Watkins, Ron; Pauly, Kim Butts

    2009-04-01

    For HIFU treatments without significant heating, MR monitoring could be done by imaging the acoustic radiation force (MR-ARFI). MR-ARFI used motion-sensitizing gradients to encode the small displacement induced by the acoustic radiation force into the phase of the image. Unfortunately, large conventional gradients render the image sensitive to motion, and susceptible to artifacts, which are seen as a non-linear background phase and can be larger than the displacement-induced phase. In this work, MR-ARFI encoding gradients are optimized to minimize these problems. The proposed repeated bipolar gradients are robust against motion and eddy current, and the SNR is significantly enhanced at no cost of scan time or encoding sensitivity.

  1. Effective acoustic properties of a meta-material consisting of small Helmholtz resonators

    Lamacz, Agnes; Schweizer, Ben

    2016-01-01

    We investigate the acoustic properties of meta-materials that are inspired by sound-absorbing structures. We show that it is possible to construct meta-materials with frequency-dependent effective properties, with large and/or negative permittivities. Mathematically, we investigate solutions $u^\\varepsilon: \\Omega_\\varepsilon \\rightarrow \\mathbb{R}$ to a Helmholtz equation in the limit $\\varepsilon\\rightarrow 0$ with the help of two-scale convergence. The domain $\\Omega_\\varepsilon$ is obtain...

  2. A surface acoustic wave (SAW)-enhanced grating-coupling phase-interrogation surface plasmon resonance (SPR) microfluidic biosensor.

    Sonato, A; Agostini, M; Ruffato, G; Gazzola, E; Liuni, D; Greco, G; Travagliati, M; Cecchini, M; Romanato, F

    2016-03-23

    A surface acoustic wave (SAW)-enhanced, surface plasmon resonance (SPR) microfluidic biosensor in which SAW-induced mixing and phase-interrogation grating-coupling SPR are combined in a single lithium niobate lab-on-a-chip is demonstrated. Thiol-polyethylene glycol adsorption and avidin/biotin binding kinetics were monitored by exploiting the high sensitivity of grating-coupling SPR under azimuthal control. A time saturation binding kinetics reduction of 82% and 24% for polyethylene and avidin adsorption was obtained, respectively, due to the fluid mixing enhancement by means of the SAW-generated chaotic advection. These results represent the first implementation of a nanostructured SAW-SPR microfluidic biochip capable of significantly improving the molecule binding kinetics on a single, portable device. In addition, the biochip here proposed is suitable for a great variety of biosensing applications. PMID:26932784

  3. Hydro-acoustic resonance behavior in presence of a precessing vortex rope: observation of a lock-in phenomenon at part load Francis turbine operation

    Favrel, A.; Landry, C.; Müller, A.; Yamamoto, K.; Avellan, F.

    2014-03-01

    Francis turbines operating at part load condition experience the development of a cavitating helical vortex rope in the draft tube cone at the runner outlet. The precession movement of this vortex rope induces local convective pressure fluctuations and a synchronous pressure pulsation acting as a forced excitation for the hydraulic system, propagating in the entire system. In the draft tube, synchronous pressure fluctuations with a frequency different to the precession frequency may also be observed in presence of cavitation. In the case of a matching between the precession frequency and the synchronous surge frequency, hydro-acoustic resonance occurs in the draft tube inducing high pressure fluctuations throughout the entire hydraulic system, causing torque and power pulsations. The risk of such resonances limits the possible extension of the Francis turbine operating range. A more precise knowledge of the phenomenon occurring at such resonance conditions and prediction capabilities of the induced pressure pulsations needs therefore to be developed. This paper proposes a detailed study of the occurrence of hydro-acoustic resonance for one particular part load operating point featuring a well-developed precessing vortex rope and corresponding to 64% of the BEP. It focuses particularly on the evolution of the local interaction between the pressure fluctuations at the precession frequency and the synchronous surge mode passing through the resonance condition. For this purpose, an experimental investigation is performed on a reduced scale model of a Francis turbine, including pressure fluctuation measurements in the draft tube and in the upstream piping system. Changing the pressure level in the draft tube, resonance occurrences are highlighted for different Froude numbers. The evolution of the hydro-acoustic response of the system suggests that a lock-in effect between the excitation frequency and the natural frequency may occur at low Froude number, inducing a hydro-acoustic

  4. Hydro-acoustic resonance behavior in presence of a precessing vortex rope: observation of a lock-in phenomenon at part load Francis turbine operation

    Francis turbines operating at part load condition experience the development of a cavitating helical vortex rope in the draft tube cone at the runner outlet. The precession movement of this vortex rope induces local convective pressure fluctuations and a synchronous pressure pulsation acting as a forced excitation for the hydraulic system, propagating in the entire system. In the draft tube, synchronous pressure fluctuations with a frequency different to the precession frequency may also be observed in presence of cavitation. In the case of a matching between the precession frequency and the synchronous surge frequency, hydro-acoustic resonance occurs in the draft tube inducing high pressure fluctuations throughout the entire hydraulic system, causing torque and power pulsations. The risk of such resonances limits the possible extension of the Francis turbine operating range. A more precise knowledge of the phenomenon occurring at such resonance conditions and prediction capabilities of the induced pressure pulsations needs therefore to be developed. This paper proposes a detailed study of the occurrence of hydro-acoustic resonance for one particular part load operating point featuring a well-developed precessing vortex rope and corresponding to 64% of the BEP. It focuses particularly on the evolution of the local interaction between the pressure fluctuations at the precession frequency and the synchronous surge mode passing through the resonance condition. For this purpose, an experimental investigation is performed on a reduced scale model of a Francis turbine, including pressure fluctuation measurements in the draft tube and in the upstream piping system. Changing the pressure level in the draft tube, resonance occurrences are highlighted for different Froude numbers. The evolution of the hydro-acoustic response of the system suggests that a lock-in effect between the excitation frequency and the natural frequency may occur at low Froude number, inducing a hydro-acoustic

  5. A transient method for measuring the gas volume fraction in a mixed gas-liquid flow using acoustic resonance spectroscopy

    2010-01-01

    In this paper, the feasibility of measuring the gas volume fraction in a mixed gas-liquid flow by using an acoustic resonant spectroscopy (ARS) method in a transient way is studied theoretically and experimentally. Firstly, the effects of sizes and locations of a single air bubble in a cylindrical cavity with two open ends on resonant frequencies are investigated numerically. Then, a transient measurement system for ARS is established, and the trends of the resonant frequencies (RFs) and resonant amplitudes (RAs) in the cylindrical cavity with gas flux inside are investigated experimentally. The measurement results by the proposed transient method are compared with those by steady-state ones and numerical ones. The numerical results show that the RFs of the cavity are highly sensitive to the volume of the single air bubble. A tiny bubble volume perturbation may cause a prominent RF shift even though the volume of the air bubble is smaller than 0.1% of that of the cavity. When the small air bubble moves, the RF shift will change and reach its maximum value as it is located at the middle of the cavity. As the gas volume fraction of the two-phase flow is low, both the RFs and RAs from the measurement results decrease dramatically with the increasing gas volume, and this decreasing trend gradually becomes even as the gas volume fraction increases further. These experimental results agree with the theoretical ones qualitatively. In addition, the transient method for ARS is more suitable for measuring the gas volume fraction with randomness and instantaneity than the steady-state one, because the latter could not reflect the random and instant characteristics of the mixed fluid due to the time consumption for frequency sweeping. This study will play a very important role in the quantitative measurement of the gas volume fraction of multiphase flows.

  6. A proof of principle experiment: Structural transitions in self-healing poly (ethylene co-methacrylic acid) ionomers using acoustic and ultrasonic time dependent resonant spectroscopy

    K. A. Pestka II; S. J. Kalista; A. Ricci

    2013-01-01

    We demonstrate a method for assessing structural transitions in self-healing poly (ethylene co-methacrylic acid) ionomers as a function of time, by observing the evolution of their acoustic and ultrasonic resonant spectra and associated quality factors during the post-damage healing phase. Two samples composed of EMAA-0.6Na and EMAA-0.3Na were scanned from 1 kHz to 2 MHz before and after a damage event. After damage, time varying resonances were discovered using time dependent resonant spectr...

  7. Tunable Ba0.5Sr0.5TiO3 film bulk acoustic resonators using SiO2/Mo Bragg reflectors

    Tunable and switchable Ba0.5Sr0.5TiO3 film bulk acoustic resonators (FBARs) based on SiO2/Mo Bragg reflectors are explored, which can withstand high temperature for the deposition of BaxSr1−xTiO3 (BST) films at 800 °C. The dc bias-dependent resonance may be attributed to the piezoelectricity of the BST film induced by an electrostrictive effect. The series resonant frequency is strongly dc bias-dependent and shifts downwards with dc bias increasing, while the parallel resonant frequency is only weakly dc bias-dependent and slightly shifts upwards at low dc bias (< 45 V) while downwards at higher dc bias. The calculated relative tunability of shifts at series resonance frequency is around −2.3% and the electromechanical coupling coefficient is up to approximately 8.09% at 60-V dc bias, which can be comparable to AlN FBARs. This suggests that a high-quality tunable BST FBAR device can be achieved through the use of molybdenum (Mo) as the high acoustic impedance layer in a Bragg reflector, which not only provides excellent acoustic isolation from the substrate, but also improves the crystallinity of BST films withstanding higher deposition temperature

  8. Testing the neutrality of matter by acoustic means in a spherical resonator

    Bressi, G; Della Valle, F; Galeazzi, G; Ruoso, G; Sartori, G

    2011-01-01

    New measurements to test the neutrality of matter by acoustic means are reported. The apparatus is based on a spherical capacitor filled with gaseous SF$_6$ excited by an oscillating electric field. The apparatus has been calibrated measuring the electric polarizability. Assuming charge conservation in the $\\beta$ decay of the neutron, the experiment gives a limit of $\\epsilon_\\text{p-e}\\lesssim1\\cdot10^{-21}$ for the electron-proton charge difference, the same limit holding for the charge of the neutron. Previous measurements are critically reviewed and found incorrect: the present result is the best limit obtained with this technique.

  9. The Liquid Sensor Using Thin Film Bulk Acoustic Resonator with C-Axis Tilted AlN Films

    Ying-Chung Chen

    2013-01-01

    Full Text Available Dual-mode thin film bulk acoustic resonator (TFBAR devices are fabricated with c-axis tilted AlN films. To fabricate dual-mode TFBAR devices, the off-axis RF magnetron sputtering method for the growth of tilted piezoelectric AlN thin films is adopted. In this report, the AlN thin films are deposited with tilting angles of 15° and 23°. The frequency response of the TFBAR device with 23° tilted AlN thin film is measured to reveal its ability to provide dual-mode resonance. The sensitivities of the longitudinal and shear modes to mass loading are calculated to be 2295 Hz cm2/ng and 1363 Hz cm2/ng with the mechanical quality factors of 480 and 287, respectively. The sensitivities of the longitudinal and shear modes are calculated to be 0 and 15 Hz cm2/μg for liquid loading.

  10. Measurement of pipe wall thinning by ultra acoustic resonance technique using optical fiber

    This is the novel system for Pipe Wall Thickness measurement which is combined EAMT(Electro Magnetic Acoustic Transducer) and Optical Fiber Sensor. The conventional ultrasonic thickness meter is using in pipe wall thickness measurement. However, it is necessary to remove a heat insulator from pipe line. A characteristic of this novel system is that it is possible to measure without removing a heat insulator and on-line monitoring, because of measurement probe is attached between pipe surface and heat insulator. As a result of measured with this system, we could measure 30 mm thickness of carbon and stainless steel at the maximum and pipe specimen of elbow shape. Heat-resistant characteristic confirmed at 200 degrees C until about 7000 hours. (author)

  11. Equilibrium shape and location of a liquid drop acoustically positioned in a resonant rectangular chamber

    Jackson, H. W.; Barmatz, M.; Shipley, C.

    1988-01-01

    The effect of a standing wave field in a rectangular chamber on the shape and location of an acoustically positioned drop or bubble is calculated. The sample deformation and equilibrium position are obtained from an analysis of the spherical harmonic projections of the total surface stress tensor. The method of calculation relies on the assumed condition that the sample is only slightly distorted from a spherical form. The equilibrium location of a levitated drop is combined with a formula introduced by Hasegawa (1979) to calcualte the ka dependence of the radiation force function. The present theory is valid for large as well as small ka values. Calculations in the small ka limit agree with previous theories and experimental results. Examples are presented for nonplane-wave modes as well as plane-wave rectangular modes.

  12. A Methodology to Integrate Magnetic Resonance and Acoustic Measurements for Reservoir Characterization

    Parra, Jorge O.; Hackert, Chris L.; Ni, Qingwen; Collier, Hughbert A.

    2000-09-22

    This report contains eight sections. Some individual subsections contain lists of references as well as figures and conclusions when appropriate. The first section includes the introduction and summary of the first-year project efforts. The next section describes the results of the project tasks: (1) implementation of theoretical relations between effect dispersion and the stochastic medium, (2) imaging analyses using core and well log data, (3) construction of dispersion and attenuation models at the core and borehole scales in poroelastic media, (4) petrophysics and a catalog of core and well log data from Siberia Ridge field, (5) acoustic/geotechnical measurements and CT imaging of core samples from Florida carbonates, and (6) development of an algorithm to predict pore size distribution from NMR core data. The last section includes a summary of accomplishments, technology transfer activities and follow-on work for Phase II.

  13. Theoretical interpretation of a case study: Acoustic resonance in an archaeological site

    Carrera, Jorge; Beristain, Sergio

    2002-11-01

    It is well-known that the stairways of some Mexican archaeological sites, like Chichen-Itza or Teotihuacan, present an interesting sound reflection and resonance phenomenon which causes a special audible effect. In this paper, mathematical modeling of this situation is presented, and the practical phenomenon is discussed from a theoretical standpoint. More than an end in itself, the idea is, once this validated model is obtained, to use the results for the analysis of a more extensive architectural environment in order to establish whether this kind of phenomenon would have been purposely introduced in the design of the site. This will be presented in future publications.

  14. Resonant acoustic frequencies of a tandem cascade. Part 2. Rotating blade rows

    Woodley, B. M.; Peake, N.

    1999-08-01

    In Part 1 (Woodley & Peake 1999) we described a method for predicting the occurrence of resonant states in a system comprising twin cascades in zero relative motion. We now demonstrate how that work can be extended to account for the case of more practical interest, in which the upstream cascade (rotor) is rotating in the transverse direction relative to the downstream cascade (stator). Time periodicity now forces the temporal frequency of any disturbance to be an integer multiple of the rotor passing frequency in the stator frame, and vice versa, and this leads to the requirement to sum over a discrete set of temporal modes, as well as over the spatial modes already described in Part 1. The mechanisms by which temporal and spatial modes are scattered by the blade rows is made clear by the analytical approach adopted here; the scattering of the incident pressure (and, for the stator, vorticity) fields by each row in its own frame is completed using results similar to those presented in Part 1, and the fields in the two frames then matched across the inter-row gap to provide a single matrix equation. Specimen results for the conditioning of this equation are given, and although it seems more difficult to obtain very strong excitation than it was for zero rotation, the significance of Parker resonance of the stator is again apparent.

  15. Monolithic integrated system with an electrowetting-on-dielectric actuator and a film-bulk-acoustic-resonator sensor

    Although digital microfluidics has shown great potential in a wide range of applications, a lab-on-a-chip with integrated digital droplet actuators and powerful biochemical sensors is still lacking. To address the demand, a fully integrated chip with electrowetting-on-dielectric (EWOD) and a film bulk acoustic resonator (FBAR) sensor is introduced, where an EWOD actuator manipulates digital droplets and the FBAR sensor detects the presence of substances in the droplets, respectively. The piezoelectric layer of the FBAR sensor and the dielectric layer of the EWOD share the same aluminum nitride (AlN) thin film, which is a key factor to achieve the full integration of the two completely different devices. The liquid droplets are reliably managed by the EWOD actuator to sit on or move off the FBAR sensor precisely. Sessile drop experiments and limit of detection (LOD) experiments are carried out to characterize the EWOD actuator and the FBAR sensor, respectively. Taking advantage of the digital droplet operation, a ‘dry sensing mode’ of the FBAR sensor in the lab-on-a-chip microsystem is proposed, which has a much higher signal to noise ratio than the conventional ‘wet sensing mode’. Hg2+ droplets with various concentrations are transported and sensed to demonstrate the capability of the integrated system. The EWOD–FBAR chip is expected to play an important role in many complex lab-on-a-chip applications. (paper)

  16. Analytical and experimental study of the acoustics and the flow field characteristics of cavitating self-resonating water jets

    Chahine, G.L.; Genoux, P.F.; Johnson, V.E. Jr.; Frederick, G.S.

    1984-09-01

    Waterjet nozzles (STRATOJETS) have been developed which achieve passive structuring of cavitating submerged jets into discrete ring vortices, and which possess cavitation incipient numbers six times higher than obtained with conventional cavitating jet nozzles. In this study we developed analytical and numerical techniques and conducted experimental work to gain an understanding of the basic phenomena involved. The achievements are: (1) a thorough analysis of the acoustic dynamics of the feed pipe to the nozzle; (2) a theory for bubble ring growth and collapse; (3) a numerical model for jet simulation; (4) an experimental observation and analysis of candidate second-generation low-sigma STRATOJETS. From this study we can conclude that intensification of bubble ring collapse and design of highly resonant feed tubes can lead to improved drilling rates. The models here described are excellent tools to analyze the various parameters needed for STRATOJET optimizations. Further analysis is needed to introduce such important factors as viscosity, nozzle-jet interaction, and ring-target interaction, and to develop the jet simulation model to describe the important fine details of the flow field at the nozzle exit.

  17. Monolithic integrated system with an electrowetting-on-dielectric actuator and a film-bulk-acoustic-resonator sensor

    Zhang, Menglun; Cui, Weiwei; Chen, Xuejiao; Wang, Chao; Pang, Wei; Duan, Xuexin; Zhang, Daihua; Zhang, Hao

    2015-02-01

    Although digital microfluidics has shown great potential in a wide range of applications, a lab-on-a-chip with integrated digital droplet actuators and powerful biochemical sensors is still lacking. To address the demand, a fully integrated chip with electrowetting-on-dielectric (EWOD) and a film bulk acoustic resonator (FBAR) sensor is introduced, where an EWOD actuator manipulates digital droplets and the FBAR sensor detects the presence of substances in the droplets, respectively. The piezoelectric layer of the FBAR sensor and the dielectric layer of the EWOD share the same aluminum nitride (AlN) thin film, which is a key factor to achieve the full integration of the two completely different devices. The liquid droplets are reliably managed by the EWOD actuator to sit on or move off the FBAR sensor precisely. Sessile drop experiments and limit of detection (LOD) experiments are carried out to characterize the EWOD actuator and the FBAR sensor, respectively. Taking advantage of the digital droplet operation, a ‘dry sensing mode’ of the FBAR sensor in the lab-on-a-chip microsystem is proposed, which has a much higher signal to noise ratio than the conventional ‘wet sensing mode’. Hg2+ droplets with various concentrations are transported and sensed to demonstrate the capability of the integrated system. The EWOD-FBAR chip is expected to play an important role in many complex lab-on-a-chip applications.

  18. Temperature and velocity determination of shock-heated flows with non-resonant heterodyne laser-induced thermal acoustics

    Förster, F. J.; Baab, S.; Lamanna, G.; Weigand, B.

    2015-12-01

    Non-resonant laser-induced thermal acoustics (LITA), a four-wave mixing technique, was applied to post-shock flows within a shock tube. Simultaneous single-shot determination of temperature, speed of sound and flow velocity behind incident and reflected shock waves at different pressure and temperature levels are presented. Measurements were performed non-intrusively and without any seeding. The paper describes the technique and outlines its advantages compared to more established laser-based methods with respect to the challenges of shock tube experiments. The experiments include argon and nitrogen as test gas at temperatures of up to 1000 K and pressures of up to 43 bar. The experimental data are compared to calculated values based on inviscid one-dimensional shock wave theory. The single-shot uncertainty of the technique is investigated for worst-case test conditions resulting in relative standard deviations of 1, 1.7 and 3.4 % for Mach number, speed of sound and temperature, respectively. For all further experimental conditions, calculated values stay well within the 95 % confidence intervals of the LITA measurement.

  19. Distinguishing black-hole spin-orbit resonances by their gravitational wave signatures. II: Full parameter estimation

    Trifirò, Daniele; Gerosa, Davide; Berti, Emanuele; Kesden, Michael; Littenberg, Tyson; Sperhake, Ulrich

    2015-01-01

    Gravitational waves from coalescing binary black holes encode the evolution of their spins prior to merger. In the post-Newtonian regime and on the precession timescale, this evolution has one of three morphologies, with the spins either librating around one of two fixed points ("resonances") or circulating freely. In this work we perform full parameter estimation on resonant binaries with fixed masses and spin magnitudes, changing three parameters: a conserved "projected effective spin" $\\xi$ and resonant family $\\Delta\\Phi=0,\\pi$ (which uniquely label the source); the inclination $\\theta_{JN}$ of the binary's total angular momentum with respect to the line of sight (which determines the strength of precessional effects in the waveform); and the signal amplitude. We demonstrate that resonances can be distinguished for a wide range of binaries, except for highly symmetric configurations where precessional effects are suppressed. Motivated by new insight into double-spin evolution, we introduce new variables t...

  20. Experimental validation of the band-gap and dispersive bulk modulus behaviour of locally resonant acoustic metamaterials

    Reynolds, Matthew; Gao, Yan; Daley, Stephen

    2013-01-01

    Over the last decade there has been significant interest in the design and production of acoustic metamaterials with physical qualities not seen in naturally occurring media. Progress in this area has been stimulated by the desire to create materials that exhibit novel behaviour such as negative refraction due to negative material parameters, and band gaps in the frequency response of the material. An acoustic metamaterial is presented that consists of an acoustically transparent mesh with an...

  1. Evolution of elastic and thermal properties during TMOS-gel formation determined by ringing bottle acoustic resonance spectroscopy, impulsive stimulated scattering, photopyroelectric spectroscopy and the hot ball method

    The evolution of the elastic and thermal properties of a tetramethylorthosilicate (TMOS)-based gel that exhibits an extraordinary ringing effect when enclosed in a bottle is investigated during the sol–gel transition. The results demonstrate the feasibility of three proposed experimental methods for monitoring of gels during their formation. The shear stiffening evolution during gelation is monitored by ringing bottle, resonant acoustic spectroscopy and by an ultrasonic technique using piezo electric excitation and detection. The evolution of the longitudinal modulus and the thermal diffusivity of the gel during stiffening are simultaneously determined by a combined photoacoustic and photothermal method based on heterodyne diffraction detection of impulsive stimulated scattering by, respectively, a propagating acoustic wave grating and a decaying thermal expansion grating that were both thermo elastically generated using a pulsed laser. Also, the feasibility of an inverse photopyroelectric method and a hot ball technique to monitor the thermal transport efficiency and thermal impedance of a forming gel by tracking the thermal conductivity, the thermal diffusivity, and the thermal effusivity is demonstrated. The network polymerization and stiffening during the sol–gel transition in TMOS-gel corresponds with substantial changes in the shear acoustic velocity and in all thermal properties, while the longitudinal acoustic velocity is only weakly affected. (paper)

  2. Distinguishing black-hole spin-orbit resonances by their gravitational wave signatures. II. Full parameter estimation

    Trifirò, Daniele; O'Shaughnessy, Richard; Gerosa, Davide; Berti, Emanuele; Kesden, Michael; Littenberg, Tyson; Sperhake, Ulrich

    2016-02-01

    Gravitational waves from coalescing binary black holes encode the evolution of their spins prior to merger. In the post-Newtonian regime and on the precession time scale, this evolution has one of three morphologies, with the spins either librating around one of two fixed points ("resonances") or circulating freely. In this paper we perform full parameter estimation on resonant binaries with fixed masses and spin magnitudes, changing three parameters: a conserved "projected effective spin" ξ and resonant family Δ Φ =0 ,π (which uniquely label the source); the inclination θJ N of the binary's total angular momentum with respect to the line of sight (which determines the strength of precessional effects in the waveform); and the signal amplitude. We demonstrate that resonances can be distinguished for a wide range of binaries, except for highly symmetric configurations where precessional effects are suppressed. Motivated by new insight into double-spin evolution, we introduce new variables to characterize precessing black hole binaries which naturally reflects the time scale separation of the system and therefore better encode the dynamical information carried by gravitational waves.

  3. Search for new physics in dijet resonant signatures and recent results from Run2 with the CMS experiment

    D'imperio, Giulia

    2015-01-01

    A search for narrow resonances in proton-proton collisions at a center-of-mass energy of $\\sqrt{s}=13$ TeV is presented.The dijet invariant mass distribution of the two leading jets is measured with the CMS detector using early data from Run 2 of the Large Hadron Collider.The dataset presented here was collected in July 2015 and corresponds to an integrated luminosity of 42 pb$^{-1}$.The highest observed dijet mass is 5.4 TeV.The spectrum is well described by a smooth parameterization and no evidence for new particle production is observed.Upper limits at a 95\\pct confidence level are set on the cross section of narrow resonances with masses above 1.3 TeV.

  4. Nonlinear acoustic dissipation mechanism of a slit resonator%微缝共振器的非线性吸声机理

    戴习文; 景晓东; 孙晓峰

    2011-01-01

    To simulate the vortex/sound interaction phenomenon at a slit with high sound pressure level and calculate the acoustic impedance of the slit, a discrete vortex model was set up. By combining the discrete vortex model with a one-dimensional sound propagation model, the acoustic impedance and the absorption coefficient of the slit resonator were calculated. The numerical results reveal that the acoustic properties of the slit are dominated by the vortex shedding and the evolution of the vortex sheet; the absorption coefficient of the resonator increases with the increase of the sound pressure level; the frequency of the incident sound has significant influence on the absorption coefficient of the resonator. The present results agree well with the previous direct numerical simulation (DNS) results.%为模拟高声压级时微缝处涡声相互作用现象并计算微缝声阻抗,发展了一种离散涡模型.联合微缝离散涡模型和一维声传播模型,计算了微缝共振器的声阻抗和吸声系数.数值结果表明,微缝声学性质主要取决于涡脱落和脱落涡层的演化;共振器的吸声系数随着入射声压级的增加而增大;入射声波频率对共振器吸声系数有显著影响.研究结果和先前直接数值模拟的结果符合较好.

  5. 流管侧向微缝共振器的声学特性%Acoustic properties of a slit resonator attached to a pipe with flow

    戴习文; 景晓东; 孙晓峰

    2011-01-01

    To investigate the acoustic properties of a slit resonator attached to a pipe with flow, a theoretical model based on the discrete vortex method was set up. The discontinuity conditions at the joint between the pipe and the resonator were formulated using the mass and momentum conservations, then combined with a discrete vortex model the acoustic impedance and the absorption coefficient of the resonator were computed. The numerical simulation indicates that the flow field around the slit is dominated by the rolling-up and flapping motion of the shed vortex sheet, which agrees with the previous flow visualization results and validates the "lip" assumption of the shear layer at the slit in the semi-empirical models. The present results reveal that the acoustic resistance of the resonator is mainly determined by the sound pressure levels and the grazing flow speed, while the acoustic reactance is dominated by the depth of the cavity, the thickness of the plate and end correction.%为研究有流动管道侧向微缝共振器的声学特性,基于离散涡方法建立了一个理论模型.管道安装共振器处利用质量和动量守恒建立间断条件,再结合离散涡模型,计算出共振器的声阻抗和吸声系数.数值模拟表明微缝处流场主要取决于脱落涡层的卷起和拍动,这与流场显示实验结果一致,并验证了半经验模型中微缝剪切层的"盖子"假设.结果还表明共振器声阻主要由声压级和切向流速度决定,声抗由背腔深度和面板厚度及末端修正决定.

  6. Inducing Strong Nonlinearities in a High-$Q$ System: Coupling of a Bulk Acoustic Wave Quartz Resonator to a Superconducting Quantum Interference Device

    Goryachev, Maxim; Galliou, Serge; Tobar, Michael E

    2015-01-01

    A system consisting of a SQUID amplifier coupled to a Bulk Acoustic Wave resonator is investigated experimentally from the small to large signal regimes. Both parallel and series connection topologies of the system are verified. The study reveals significant non-Duffing response that is associated with the nonlinear characteristics of Josephson junctions. The nonlinearity provides quasi-periodic structure of the spectrum in both incident power and frequency. The result gives an insight into the open loop behaviour of a future Cryogenic Quartz Oscillator operating with a SQUID amplifier as the active device.

  7. A proof of principle experiment: Structural transitions in self-healing poly (ethylene co-methacrylic acid ionomers using acoustic and ultrasonic time dependent resonant spectroscopy

    K. A. Pestka II

    2013-08-01

    Full Text Available We demonstrate a method for assessing structural transitions in self-healing poly (ethylene co-methacrylic acid ionomers as a function of time, by observing the evolution of their acoustic and ultrasonic resonant spectra and associated quality factors during the post-damage healing phase. Two samples composed of EMAA-0.6Na and EMAA-0.3Na were scanned from 1 kHz to 2 MHz before and after a damage event. After damage, time varying resonances were discovered using time dependent resonant spectroscopy (TDRS, and several of these resonances continued to evolve after visible changes in the samples ceased. These time dependent resonances enable characterization of energy dissipation, relaxation and structural ordering in self-healing ionomers. In addition, TDRS may provide a method for isolating material properties that affect the healing process, such as ion content and their associated structures as well as the effect of sample aging, which may lead to improved structural models.

  8. Evaluation of acoustic resonance at branch section in main steam line. Part 3. Evaluation of assumable factor for amplitude reduction under wet steam flow

    Flow-induced acoustic resonances of steam piping system containing closed side-branches are one of the phenomena which cause fatigue damage of piping or components in power plants. It is important to evaluate resonance frequency of branch piping, which is one of the parameters for Strouhal number as resonant condition, for design of piping system or prevention of fatigue damage in power plants. Steam piping systems of actual power plants often have wet steam condition (also nearly saturated wet steam condition). However, influence of droplets under wet steam flow on resonance frequency is not clarified qualitatively. In addition, our previous research clarified that maximum RMS amplitudes of fluctuating pressure under wet steam reduced comparing to that under dry steam where the range of steam quality 0.85 < x < 0.99 by conducting experiments in single branch under low pressure. However, the mechanism of amplitude reduction under wet steam is not clarified yet. In this study, we tried to clarify the effect of droplets on resonance frequency and damping under wet steam by theoretical analysis and cavity tone experiments in single branch. In addition, we evaluated flow regime by visual observation. As a result, assumable mechanism of amplitude reduction under wet steam was discussed. (author)

  9. Truck acoustic data analyzer system

    Haynes, Howard D.; Akerman, Alfred; Ayers, Curtis W.

    2006-07-04

    A passive vehicle acoustic data analyzer system having at least one microphone disposed in the acoustic field of a moving vehicle and a computer in electronic communication the microphone(s). The computer detects and measures the frequency shift in the acoustic signature emitted by the vehicle as it approaches and passes the microphone(s). The acoustic signature of a truck driving by a microphone can provide enough information to estimate the truck speed in miles-per-hour (mph), engine speed in rotations-per-minute (RPM), turbocharger speed in RPM, and vehicle weight.

  10. Effects of laser pulse duration and intensity on Coulomb explosion of CO2: Signatures of charge-resonance enhanced ionization

    Litvinyuk, Igor V.; Bocharova, Irina; Sanderson, Joseph; Kieffer, Jean-Claude; Légaré, François

    2009-11-01

    We studied laser-induced Coulomb explosion of CO2 by full triple-coincidence momentum resolved detection of resulting ion fragments. From the coincidence momentum data we can reconstruct molecular geometry immediately before explosion. We observe the dynamics of Coulomb explosion by comparing reconstructed CO2 geometries for different Ti:Sapphire laser pulse durations (at the same intensity) ranging from few cycles (7 fs) to 200 fs. We conclude that for longer pulse durations (>=100 fs) Coulomb explosion proceeds through the enhanced ionization mechanism taking place at the critical O-O distance of 8 a.u., similarly to well known charge-resonance enhanced ionization (CREI) in H2.

  11. (Small) Resonant non-Gaussianities: Signatures of a Discrete Shift Symmetry in the Effective Field Theory of Inflation

    Behbahani, Siavosh R.; /SLAC /Stanford U., Phys. Dept. /Boston U.; Dymarsky, Anatoly; /Princeton, Inst. Advanced Study; Mirbabayi, Mehrdad; /New York U., CCPP /New York U.; Senatore, Leonardo; /Stanford U., Phys. Dept. /KIPAC, Menlo Park

    2012-06-06

    We apply the Effective Field Theory of Inflation to study the case where the continuous shift symmetry of the Goldstone boson {pi} is softly broken to a discrete subgroup. This case includes and generalizes recently proposed String Theory inspired models of Inflation based on Axion Monodromy. The models we study have the property that the 2-point function oscillates as a function of the wavenumber, leading to oscillations in the CMB power spectrum. The non-linear realization of time diffeomorphisms induces some self-interactions for the Goldstone boson that lead to a peculiar non-Gaussianity whose shape oscillates as a function of the wavenumber. We find that in the regime of validity of the effective theory, the oscillatory signal contained in the n-point correlation functions, with n > 2, is smaller than the one contained in the 2-point function, implying that the signature of oscillations, if ever detected, will be easier to find first in the 2-point function, and only then in the higher order correlation functions. Still the signal contained in higher-order correlation functions, that we study here in generality, could be detected at a subleading level, providing a very compelling consistency check for an approximate discrete shift symmetry being realized during inflation.

  12. (Small) Resonant non-Gaussianities: Signatures of a Discrete Shift Symmetry in the Effective Field Theory of Inflation

    We apply the Effective Field Theory of Inflation to study the case where the continuous shift symmetry of the Goldstone boson π is softly broken to a discrete subgroup. This case includes and generalizes recently proposed String Theory inspired models of Inflation based on Axion Monodromy. The models we study have the property that the 2-point function oscillates as a function of the wavenumber, leading to oscillations in the CMB power spectrum. The non-linear realization of time diffeomorphisms induces some self-interactions for the Goldstone boson that lead to a peculiar non-Gaussianity whose shape oscillates as a function of the wavenumber. We find that in the regime of validity of the effective theory, the oscillatory signal contained in the n-point correlation functions, with n > 2, is smaller than the one contained in the 2-point function, implying that the signature of oscillations, if ever detected, will be easier to find first in the 2-point function, and only then in the higher order correlation functions. Still the signal contained in higher-order correlation functions, that we study here in generality, could be detected at a subleading level, providing a very compelling consistency check for an approximate discrete shift symmetry being realized during inflation.

  13. Effects of laser pulse duration and intensity on Coulomb explosion of CO2: Signatures of charge-resonance enhanced ionization

    We studied laser-induced Coulomb explosion of CO2 by full triple-coincidence momentum resolved detection of resulting ion fragments. From the coincidence momentum data we can reconstruct molecular geometry immediately before explosion. We observe the dynamics of Coulomb explosion by comparing reconstructed CO2 geometries for different Ti:Sapphire laser pulse durations (at the same intensity) ranging from few cycles (7 fs) to 200 fs. We conclude that for longer pulse durations (≥100 fs) Coulomb explosion proceeds through the enhanced ionization mechanism taking place at the critical O-O distance of 8 a.u., similarly to well known charge-resonance enhanced ionization (CREI) in H2.

  14. Acoustic streaming in microchannels

    Tribler, Peter Muller

    , and experimental results for the streaming-induced drag force dominated motion of particles suspended in a water-filled microchannel supporting a transverse half-wavelength resonance. The experimental and theoretical results agree within a mean relative dierence of approximately 20%, a low deviation given state......This thesis presents studies of boundary-driven acoustic streaming in microfluidic channels, which is a steady flow of the fluid initiated by the interactions of an oscillating acoustic standing wave and the rigid walls of the microchannel. The studies present analysis of the acoustic resonance......, the acoustic streaming flow, and the forces on suspended microparticles. The work is motivated by the application of particle focusing by acoustic radiation forces in medical, environmental and food sciences. Here acoustic streaming is most often unwanted, because it limits the focusability of particles...

  15. Signature of ferro–paraelectric transition in biferroic LuCrO{sub 3} from electron paramagnetic resonance and non-resonant microwave absorption

    Alvarez, G., E-mail: memodin@yahoo.com [Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, U.P.A.L.M, Edificio 9, Av. Instituto Politécnico Nacional S/N, San Pedro Zacatenco, México DF 07738 (Mexico); Montiel, H. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico de la Universidad Nacional Autónoma de México, Cd. Universitaria, A.P. 70-186, México DF 04510 (Mexico); Durán, A. [Centro de Nanociencias y Nanotecnología de la Universidad Nacional Autónoma de México, Km. 107, Carretera Tijuana-Ensenada, Apartado Postal 14, C.P. 22800 Ensenada, B.C. México (Mexico); Conde-Gallardo, A. [Departamento de Física, CINVESTAV-IPN, A.P. 14-740, México DF 07360 (Mexico); Zamorano, R. [Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, U.P.A.L.M, Edificio 9, Av. Instituto Politécnico Nacional S/N, San Pedro Zacatenco, México DF 07738 (Mexico)

    2014-12-15

    An electron paramagnetic resonance (EPR) study in the polycrystalline biferroic LuCrO{sub 3} is carried out at X-band (8.8–9.8 GHz) in the 295–510 K temperature range. For all the temperatures, the EPR spectra show a single broad line attributable to Cr{sup 3+} (S = 3/2) ions. The onset of a ferro–paraelectric transition has been determined from the temperature dependence of the parameters deduced from EPR spectra: the peak-to-peak linewidth (ΔH{sub pp}), the g-factor and the integral intensity (I{sub EPR}). Magnetically modulated microwave absorption spectroscopy (MAMMAS) and low-field microwave absorption (LFMA) are used to give further information on this material, where these techniques give also evidence of the ferro–paraelectric transition; indicating a behavior in agreement with a diffuse phase transition. - Highlights: • LuCrO{sub 3} powders are obtained via auto-ignition synthesis. • EPR is employed to study the onset of the ferro–paraelectric transition. • MAMMAS and LFMA techniques are used to give further information on this material.

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

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

    2009-01-01

    It is known that acoustic sensor devices, if operated in liquid phase, are sensitive not just to the mass of the analyte but also to various other parameters, such as size, shape, charge and elastic constants of the analyte as well as bound and viscously entrained water. This can be used to extract valuable information about a biomolecule, particularly if the acoustic device is combined with another sensor element which is sensitive to the mass or amount of analyte only. The latter is true in...

  17. Acoustic Treatment Design Scaling Methods. Volume 4; Numerical Simulation of the Nonlinear Acoustic Impedance of a Perforated Plate Single-Degree-of-Freedom Resonator Using a Time-Domain Finite Difference Method

    Kraft, R. E.

    1999-01-01

    Single-degree-of-freedom resonators consisting of honeycomb cells covered by perforated facesheets are widely used as acoustic noise suppression liners in aircraft engine ducts. The acoustic resistance and mass reactance of such liners are known to vary with the intensity of the sound incident upon the panel. Since the pressure drop across a perforated liner facesheet increases quadratically with the flow velocity through the facesheet, this is known as the nonlinear resistance effect. In the past, two different empirical frequency domain models have been used to predict the Sound Pressure Level effect of the incident wave on the perforated liner impedance, one that uses the incident particle velocity in isolated narrowbands, and one that models the particle velocity as the overall velocity. In the absence of grazing flow, neither frequency domain model is entirely accurate in predicting the nonlinear effect that is measured for typical perforated sheets. The time domain model is developed in an attempt to understand and improve the model for the effect of spectral shape and amplitude of multi-frequency incident sound pressure on the liner impedance. A computer code for the time-domain finite difference model is developed and predictions using the models are compared to current frequency-domain models.

  18. Flat acoustic lens by acoustic grating with curled slits

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

  19. Application of equivalent circuit analysis method in investigation of acoustic resonance mines detection model%等效电路分析法在声波探雷谐振模型研究中的应用

    陈诚; 刘丁; 张宏儒; 王驰

    2015-01-01

    利用等效电路的分析方法,定量研究声共振探雷模型的谐振机理。在论述声-地震耦合以及声共振探雷集中参数系统模型的基础上,根据机械振动与电路分析的等效原理,建立声共振探雷模型的等效电路系统模型,并用Multisim软件进行仿真分析。结果显示:在给定的参数条件下,仿真得到的共振频率和反共振频率分别为157 Hz和503 Hz,与实验测得的共振频率150 Hz和反共振频率513 Hz基本吻合。表明等效电路分析方法是定量研究声共振探雷模型谐振机理的一个有效手段,Multisim软件为研究地雷和土壤参数条件复杂变化情况下的声波探雷技术提供了一种灵活的工具。%The equivalent circuit analysis method is used to quantitatively research the principle of the acoustic res-onance model for buried mines detection.Based on the acoustic-to-seismic coupling and the acoustic resonance pa-rameter lumped model, the equivalent circuit system of acoustic resonance landmine detection model is developed. The software, Multisim, is used to analyze the equivalent circuit.The results show that the simulated resonance and anti-resonance frequency is 157 Hz and 503 Hz respectively, which is agreement with the experimentally measured resonance frequency 150 Hz and anti-resonance frequency 513 Hz.Therefore, the equivalent circuit analysis meth-od is proved to be an effective approach to quantitatively research the resonance principle of the acoustic resonance landmine detection model.And the software, Multisim, is a flexible tool to study the acoustic resonance landmine detection model.

  20. Resonances

    an impetus or drive to that account: change, innovation, rupture, or discontinuity. Resonances: Historical Essays on Continuity and Change explores the historiographical question of the modes of interrelation between these motifs in historical narratives. The essays in the collection attempt to...... realize theoretical consciousness through historical narrative ‘in practice’, by discussing selected historical topics from Western cultural history, within the disciplines of history, literature, visual arts, musicology, archaeology, philosophy, and theology. The title Resonances indicates the overall...

  1. Characterization of condenser microphones under different environmental conditions for accurate speed of sound measurements with acoustic resonators

    Condenser microphones are more commonly used and have been extensively modeled and characterized in air at ambient temperature and static pressure. However, several applications of interest for metrology and physical acoustics require to use these transducers in significantly different environmental conditions. Particularly, the extremely accurate determination of the speed of sound in monoatomic gases, which is pursued for a determination of the Boltzmann constant k by an acoustic method, entails the use of condenser microphones mounted within a spherical cavity, over a wide range of static pressures, at the temperature of the triple point of water (273.16 K). To further increase the accuracy achievable in this application, the microphone frequency response and its acoustic input impedance need to be precisely determined over the same static pressure and temperature range. Few previous works examined the influence of static pressure, temperature, and gas composition on the microphone's sensitivity. In this work, the results of relative calibrations of 1/4 in. condenser microphones obtained using an electrostatic actuator technique are presented. The calibrations are performed in pure helium and argon gas at temperatures near 273 K and in the pressure range between 10 and 600 kPa. These experimental results are compared with the predictions of a realistic model available in the literature, finding a remarkable good agreement. The model provides an estimate of the acoustic impedance of 1/4 in. condenser microphones as a function of frequency and static pressure and is used to calculate the corresponding frequency perturbations induced on the normal modes of a spherical cavity when this is filled with helium or argon gas.

  2. Thermalization properties at mK temperatures of a nanoscale optomechanical resonator with acoustic-bandgap shield

    Meenehan, Sean M.; Cohen, Justin D.; Groeblacher, Simon; Hill, Jeff T.; Safavi-Naeini, Amir H.; Aspelmeyer, Markus; Painter, Oskar

    2014-01-01

    Optical measurements of a nanoscale silicon optomechanical crystal cavity with a mechanical resonance frequency of 3.6 GHz are performed at sub-kelvin temperatures. We infer optical-absorption-induced heating and damping of the mechanical resonator from measurements of phonon occupancy and motional sideband asymmetry. At the lowest probe power and lowest fridge temperature(T_f = 10 mK), the localized mechanical resonance is found to couple at a rate of γ_i/2π = 400 Hz (Q_m = 9 x 10^6...

  3. Postoperative magnetic resonance imaging after acoustic neuroma surgery. Influence of packing materials in the drilled internal auditory canal on assessment of residual tumor

    Umezu, Hiromichi; Seki, Yojiro [Toranomon Hospital, Tokyo (Japan)

    1999-02-01

    Serial magnetic resonance (MR) images taken after acoustic neuroma surgery were analyzed to evaluate the pattern and timing of postoperative contrast enhancement in 22 patients who underwent acoustic neuroma removal via the suboccipital transmeatal approach. The opened internal auditory canal (IAC) was covered with a muscle piece in nine patients and with fibrin glue in 13. A total of 56 MR imaging examinations were obtained between days 1 and 930 after surgery. MR imaging showed linear enhancement at the IAC within the first 2 days after surgery, and revealed nodular enhancement on day 3 or later in patients with a muscle piece. MR imaging tended to show linear enhancement at the IAC, irrespective of the timing of the examination in the patients with fibrin glue. Postoperative MR imaging on day 3 or later showed the incidence of nodular enhancement in patients with muscle was significantly higher than in patients with fibrin glue. The results illustrate the difficulty in differentiating nodular enhancement of a muscle piece from tumor by a single postoperative MR imaging study. Therefore, fibrin glue is generally advocated as a packing material of the IAC because it rarely shows masslike enhancement on postoperative MR imaging. When a muscle piece is used in patients at high risk for postoperative cerebrospinal fluid leaks, MR imaging should be obtained within the first 2 days after surgery, since benign enhancement of muscle will not occur and obscure the precise extent of tumor resection. (author)

  4. Comparison of three lines of broiler breeders differing in ascites susceptibility or growth rate. 1. Relationship between acoustic resonance data and embryonic or hatching parameters.

    Tona, K; Kemps, B; Bruggeman, V; Bamelis, F; De Smit, L; Onagbesan, O; De Baerdemaeker, J; Decuypere, E

    2005-09-01

    Ascites is a prevalent cardiovascular disease among modern broilers with negative impacts on production and animal welfare. The peak of mortality due to ascites occurs at the end of the growing period, but the etiology of this problem may start during embryonic development. A few recent reports have demonstrated that the signs of ascites susceptibility are manifested during the late stages of incubation. In the current study, we used a nondestructive method based on egg acoustic resonance parameters [resonant frequency (RF) and damping] to establish a relationship between embryo physiological events during early development in broiler eggs and susceptibility to ascites. The hatching eggs of 3 broiler lines differing in ascites susceptibility were used for this study: ascites-resistant dam line (DAR), ascites-sensitive dam line (DAS), and ascites-sensitive sire line (SASL). These lines were selected on the basis of fast growth, high breast meat yield, and ascites induction at low temperatures such that the order of ascites susceptibility in terms of mortality was SASL > DAS > DAR. Eggs were incubated under standard conditions in forced-draft incubators. We measured egg weights at setting, albumen pH, Haugh units (HU) at setting, and embryo weights at d 11 and 18, at internal pipping (IP), and at hatch. The durations of IP, external pipping (EP), and hatching were also determined. At 2 hourly periods during incubation, egg RF and damping were also measured. There were differences in egg weights between DAR and SASL vs. DAS, but albumen HU, albumen pH, and the ratio of yolk weight to egg weight were similar. There were differences in RF, damping, embryonic growth rates, and hatching events. Changes in resonant frequency and damping, which certainly suggest eggshell differences among lines, were not totally related to variations in physiological events during early and late embryonic development. A comparison between DAR and DAS, between DAS and SASL, or DAR and SASL

  5. Thermalization properties at mK temperatures of a nanoscale optomechanical resonator with acoustic-bandgap shield

    Meenehan, Sean M; Groeblacher, Simon; Hill, Jeff T; Safavi-Naeini, Amir H; Aspelmeyer, Markus; Painter, Oskar

    2014-01-01

    Optical measurements of a nanoscale silicon optomechanical crystal cavity with a mechanical resonance frequency of 3.6GHz are performed at sub-kelvin temperatures. We infer optical-absorption-induced heating and damping of the mechanical resonator from measurements of phonon occupancy and motional sideband asymmetry. At the lowest probe power and lowest fridge temperature (10mK), the localized mechanical resonance is found to couple at a rate of 400Hz (Q=9x10^6) to a thermal bath of temperature 270mK. These measurements indicate that silicon optomechanical crystals cooled to millikelvin temperatures should be suitable for a variety of experiments involving coherent coupling between photons and phonons at the single quanta level.

  6. Design and Modelling of a Two-port Surface Acoustic WaveResonator using Coupling-of-modes Theory

    Mamta Khaneja

    2008-05-01

    Full Text Available In this present paper the coupling-of-modes theory has been used to design and simulatethe characteristics of a two-port SAW resonator with shorted reflection gratings to define theresonance cavity. A resonator device at 150 MHz has been designed and fabricated on ST-Quartz. It is found that the simulated and experimental characteristics of the device are in closeagreement. The results show that the SAW designs based on coupling-of-modes formulationare adequate for most applications.

  7. Effects of core position of locally resonant scatterers on low-frequency acoustic absorption in viscoelastic panel

    Zhong, Jie; Wen, Ji-Hong; Zhao, Hong-Gang; Yin, Jian-Fei; Yang, Hai-Bin

    2015-08-01

    Locally resonant sonic materials, due to their ability to control the propagation of low-frequency elastic waves, have become a promising option for underwater sound absorption materials. In this paper, the finite element method is used to investigate the absorption characteristics of a viscoelastic panel periodically embedded with a type of infinite-long non-coaxially cylindrical locally resonant scatterers (LRSs). The effect of the core position in the coating layer of the LRS on the low-frequency (500 Hz-3000 Hz) sound absorption property is investigated. With increasing the longitudinal core eccentricity e, there occur few changes in the absorptance at the frequencies below 1500 Hz, however, the absorptance above 1500 Hz becomes gradually better and the valid absorption (with absorptance above 0.8) frequency band (VAFB) of the viscoelastic panel becomes accordingly broader. The absorption mechanism is revealed by using the displacement field maps of the viscoelastic panel and the steel slab. The results show two typical resonance modes. One is the overall resonance mode (ORM) caused by steel backing, and the other is the core resonance mode (CRM) caused by LRS. The absorptance of the viscoelastic panel by ORM is induced mainly by the vibration of the steel slab and affected little by core position. On the contrary, with increasing the core eccentricity, the CRM shifts toward high frequency band and decouples with the ORM, leading to two separate absorption peaks and the broadened VAFB of the panel. Project supported by the National Natural Science Foundation of China (Grant No. 51275519).

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

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

  9. Acoustic monitoring method and device

    The present invention provides a method of eliminating resonance noises upon acoustically monitoring the operation state of power plants and plant equipments whether they are normal or not, to improve sensitivity for detecting abnormalities. Namely, a microphone detects acoustic signals including leaking sounds and converts them into electric signals. An amplifier amplifies the electric signals to an appropriate level. A noise eliminating section eliminates resonance noises other than the leaking sounds. An abnormality judging section judges presence of abnormality based on the level of the acoustic signals of the leaking sounds. With such a constitution, a plurality of resonance noises generated also during normal plant operation are automatically eliminated. Since resonance noises as a factor of lowering the sensitivity for abnormal sound detection are not included in the acoustic signals, the sensitivity for the abnormal sound detection is improved. Accordingly, the performance of the acoustic monitoring device is improved. (I.S.)

  10. Cochlear bionic acoustic metamaterials

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Fu, Gang; Bai, Changan

    2014-11-01

    A design of bionic acoustic metamaterial and acoustic functional devices was proposed by employing the mammalian cochlear as a prototype. First, combined with the experimental data in previous literatures, it is pointed out that the cochlear hair cells and stereocilia cluster are a kind of natural biological acoustic metamaterials with the negative stiffness characteristics. Then, to design the acoustic functional devices conveniently in engineering application, a simplified parametric helical structure was proposed to replace actual irregular cochlea for bionic design, and based on the computational results of such a bionic parametric helical structure, it is suggested that the overall cochlear is a local resonant system with the negative dynamic effective mass characteristics. There are many potential applications in the bandboard energy recovery device, cochlear implant, and acoustic black hole.

  11. Islets of Meningioma in an Acoustic Schwannoma in a Patient with Neurofibromatosis-2: Pathology and Magnetic Resonance Imaging Findings

    Mixed tumors of the cerebellopontine angle, composed of meningioma and schwannoma components, are extremely rare; so far, only 12 cases have been reported in the literature. They are thought to be exclusively associated with neurofibromatosis-2. We present a mixed tumor of schwannoma and meningioma in a patient with neurofibromatosis-2 and discuss the pathology and magnetic resonance imaging (MRI) findings in relation to the literature. Review of the literature shows that a typical MRI pattern has not been established for mixed tumors and it seems unlikely that a meningioma component can be differentiated within a schwannoma preoperatively

  12. CERTIFICATELESS SIGNATURE AND BLIND SIGNATURE

    Zhang Lei; Zhang Futai

    2008-01-01

    Certificateless public key cryptography is a new paradigm introduced by AI-Riyami and Paterson. It eliminates the need of the certificates in traditional public key cryptosystems and the key escrow problem in IDentity-based Public Key Cryptography (ID-PKC). Due to the advantages of the certificateless public key cryptography,a new efficient certificateless pairing-based signature scheme is presented,which has some advantages over previous constructions in computational cost. Based on this new signature scheme,a certificateless blind signature scheme is proposed. The security of our schemes is proven based on the hardness of computational Diffie-Hellman problem.

  13. Small-scale field-aligned currents and ionospheric disturbances induced by vertical acoustic resonance during the 2015 eruption of Chile's Calbuco volcano

    Aoyama, T.; Iyemori, T.; Nakanishi, K.; Nishioka, M.

    2015-12-01

    Wave packet structure of small-scale magnetic fluctuations were observed by SWARM satellites just above the volcano and it's magnetic conjugate point after the eruption of Chile's Calbuco volcano on April 22, 2015. These magnetic fluctuations in low and middle latitudes generated by small-scale field aligned currents (FACs), and have about 10-30 seconds period along the satellites' orbit [Nakanishi et al., 2014] and about 200 (340) seconds temporal scale for meridional (longitudinal) magnetic components [Iyemori et al., 2015]. We also observed ionospheric disturbances and ground geomagnetic fluctuations just after the eruption. The 4-min period oscillations of total electron content (TEC) were observed by GPS receivers near the volcano. The 260 and 215 seconds spectral peaks in D component of ground based geomagnetic observation were found. Such oscillations and spectral peaks didn't exist before the eruption. All of these observations may have the same origin, i.e., vertical acoustic resonance between the ionosphere and the ground. In this presentation, we estimate the propagation velocity of the TEC oscillations and the spatial scale of the disturbance region in the E-layer where the FACs are generated by the ionospheric dynamo.

  14. Elastic relaxations associated with the Pm3m-R3c transition in LaA103 III: superattenuation of acoustic resonances

    Darling, Timothy W [Los Alamos National Laboratory; Carpenter, M A [UNIV OF CAMBRIDGE; Buckley, A [UNIV OF CAMBRIDGE; Taylor, P A [UNIV OF CAMBRIDGE; Mcknight, R E A [UNIV OF CAMBRIDGE

    2009-01-01

    Resonant Ultrasound Spectroscopy has been used to characterize elastic softening and a variety of new acoustic dissipation processes associated with the Pm{bar 3}m {leftrightarrow} R{bar 3}c transition in single crystal and ceramic samples of LaAlO{sub 3}. Softening of the cubic structure ahead of the transition point is not accompanied by an increase in dissipation but follows different temperature dependences for the bulk modulus, 1/3(C{sub 11} + 2C{sub 12}), and the shear components 1/2(C{sub 11}-C{sub 12}) and C{sub 44} as if the tilting instability contains two slightly different critical temperatures. The transition itself is marked by the complete disappearance of resonance peaks (superattenuation), which then reappear below {approx}700 K in spectra from single crystals. Comparison with low frequency, high stress data from the literature indicate that the dissipation is not due to macroscopic displacement of needle twins. An alternative mechanism, local bowing of twin walls under low dynamic stress, is proposed. Pinning of the walls with respect to this displacement process occurs below {approx}350 K. Anelasticity maps, analogous to plastic deformation mechanism maps, are proposed to display dispersion relations and temperature/frequency/stress fields for different twin wall related dissipation mechanisms. An additional dissipation process, with an activation energy of 43 {+-} 6 kJ.mole{sup -1}, occurs in the vicinity of 250 K. The mechanism for this is not known, but it is associated with C{sub 44} and therefore appears to be related in some way to the cubic {leftrightarrow} rhombohedral transition at {approx}817 K. Slight softening in the temperature interval {approx}220 {yields} 70 K of resonance peaks determined by shear elastic constants hints at an incipient E{sub g} ferroelastic instability in LaAlO{sub 3}. The softening interval ends with a further dissipation peak at {approx} 60 K, the origin of which is discussed in terms of freezing of atomic

  15. Acoustic Metamaterials and Phononic Crystals

    2013-01-01

    This comprehensive book presents all aspects of acoustic metamaterials and phononic crystals. The emphasis is on acoustic wave propagation phenomena at interfaces such as refraction, especially unusual refractive properties and negative refraction. A thorough discussion of the mechanisms leading to such refractive phenomena includes local resonances in metamaterials and scattering in phononic crystals.

  16. Effect of the ion-acoustic plasma turbulence on the development of the parametric instability nearby the low hybrid resonance

    The parametric plasma instability on HF heating near the low hybrid resonance in the process of developing the ion sound turbulence in an original by currentless plasma is studied experimentally. A cylinder plasma column was produced in a homogeneous magnetic field by the electron beam at 60-100 eV. Argon was used as the operating gas. The pressure of argon was of 2.5 - 2.7 10-4 Tor. The low frequency noises of the plasma were recorded by the single Langmuir probe according to fluctuations of the ion saturation current. The experiment was carried out under conditions when Ωsub(i) 0 is the circular frequency of the pumping wave, Ωsub(i), ωsub(Li) are the ion cyclotron and Langmuir frequencies, ωsub(LH) - is the Low hybrid frequency). The investigation shows that the parametric excitation of ion sound noises and HF oscillations near the pumping wave frequency takes place over a wide range of frequencies with the spectrum analogous to the spectrum of the ion-sound turbulence. The experimental observations indicate an effect of the sound turbulence and that of the form of the velocity distribution function of charged particles on parametric buildup of the waves

  17. Radiation signatures

    A new concept for modelling radiation risk is proposed. This concept is based on the proposal that the spectrum of molecular lesions, which we dub ''the radiation signature'', can be used to identify the quality of the causal radiation. If the proposal concerning radiation signatures can be established then, in principle, both prospective and retrospective risk determination can be assessed on an individual basis. A major goal of biophysical modelling is to relate physical events such as ionization, excitation, etc. to the production of radiation carcinogenesis. A description of the physical events is provided by track structure. The track structure is determined by radiation quality, and it can be considered to be the ''physical signature'' of the radiation. Unfortunately, the uniqueness characteristics of this signature are dissipated in biological systems in ∼10-9s. Nonetheless, it is our contention that this physical disturbance of the biological system eventuates later, at ∼100s, in molecular lesion spectra which also characterize the causal radiation. (author)

  18. ELECTRODYNAMIC LOUDSPEAKER-DRIVEN ACOUSTIC COMPRESSOR

    Martin Šoltés; Milan Červenka

    2015-01-01

    An acoustic compressor is  built  using the acoustic resonator which shape was optimized for a maximum acoustic pressure amplitude and a low-cost compression driver.  Acoustic compressor is built  by installing  a suction port in the resonator wall where the standing wave has its pressure node and a delivery port with a valve in the resonator wall where the standing wave has its pressure anti-node. Different reeds, serving  as delivery valves, are tested and their performance is investigated....

  19. Violins characterization through vibro-acoustic experiments

    RAVINA, Enrico

    2012-01-01

    International audience An approach of integrated vibratory and acoustic experiments oriented to identify the specific characteristics and peculiarities of violins is presented in the paper. Today the up-level luthery handicraft needs a scientific and methodical supports specifically oriented to underline the acoustic peculiarities of each musical instrument, able to define the “signature” of a specific instrument. The proposed approach integrates vibration and acoustic non destructive anal...

  20. Narrow terahertz attenuation signatures in Bacillus thuringiensis.

    Zhang, Weidong; Brown, Elliott R; Viveros, Leamon; Burris, Kellie P; Stewart, C Neal

    2014-10-01

    Terahertz absorption signatures from culture-cultivated Bacillus thuringiensis were measured with a THz photomixing spectrometer operating from 400 to 1200 GHz. We observe two distinct signatures centered at ∼955 and 1015 GHz, and attribute them to the optically coupled particle vibrational resonance (surface phonon-polariton) of Bacillus spores. This demonstrates the potential of the THz attenuation signatures as "fingerprints" for label-free biomolecular detection. PMID:23821459

  1. Compact acoustic refrigerator

    Bennett, Gloria A.

    1992-01-01

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  2. Acoustic coherent perfect absorbers

    In this paper, we explore the possibility of achieving acoustic coherent perfect absorbers. Through numerical simulations in two dimensions, we demonstrate that the energy of coherent acoustic waves can be totally absorbed by a fluid absorber with specific complex mass density or bulk modulus. The robustness of such absorbing systems is investigated under small perturbations of the absorber parameters. We find that when the resonance order is the lowest and the size of the absorber is comparable to the wavelength in the background, the phenomenon of perfect absorption is most stable. When the wavelength inside both the background and the absorber is much larger than the size of the absorber, perfect absorption is possible when the mass density of the absorber approaches the negative value of the background mass density. Finally, we show that by using suitable dispersive acoustic metamaterials, broadband acoustic perfect absorption may be achieved. (papers)

  3. Flat acoustic lens by acoustic grating with curled slits

    Peng, Pai

    2014-10-01

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

  4. Communication Acoustics

    Blauert, Jens

    Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

  5. 2D CFD simulation of fluid-resonant acoustic oscillation induced by mean flow%流体谐振型时均流诱导声振荡二维数值模拟

    麻剑锋; 刘凯凯; 徐雅; 沈新荣; 孙大明

    2013-01-01

    针对时均流通过十字型深腔结构时产生的“流体谐振型”声振荡现象,采用大涡模拟方法进行数值模拟研究.发现动态Smagorinsky-Lilly模型和壁面自适应局部涡黏模型均能较好描述振荡频率和压力振幅随时均流速的变化规律,但后者对雷诺应力预测不足.计算结果表明,在支管内会形成典型的驻波声场,并随着流速的变化表现出不同的水力模态和声学模态特征.在此基础上,揭示流体谐振型时均流诱导声振荡的发生机理:驻波声场影响涡结构的脱落以及运动轨迹,而涡结构在运动过程中向谐振腔内的声场输出能量,完成两者的耦合作用.%To study the fluid-resonant acoustic oscillation phenomenon induced by the mean flow in a cross-junction deep cavity, the Large-Eddy Simulation (LES) is applied. The result indicates that the dynamic Smagorinsky-Lilly model and the wall-adapted local eddy-viscosity model both can predict the changing rule of oscillation frequency and pressure amplitude. But the latter gives smaller Reynolds stress. It is shown that a standing wave acoustic field forms in the branch tube, and the hydrodynamic mode and acoustic mode change with the mean flow velocity. On this basis, the mechanism of the fluid-resonant oscillation induced by the mean flow is revealed, showing that vortex shedding at the upstream edge of cavity and vortex movement locus are significantly influenced by the acoustic field. On the other hand, vortex structures transfer energy into the acoustic field as they move along the opening of the cavity, thus accomplishing the coupling between the mean flow and the acoustic field.

  6. Acoustic Neuroma

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. The tumor ... press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the symptoms ...

  7. Acoustic Neuroma

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  8. Distribution of small dispersive coal dust particles and absorbed radioactive chemical elements in conditions of forced acoustic resonance in iodine air filter at nuclear power plant

    Ledenyov, Oleg P

    2013-01-01

    The physical features of distribution of the small dispersive coal dust particles and the adsorbed radioactive chemical elements and their isotopes in the absorber with the granular filtering medium with the cylindrical coal granules were researched in the case of the intensive air dust aerosol stream flow through the iodine air filter (IAF). It was shown that, at the certain aerodynamic conditions in the IAF, the generation of the acoustic oscillations is possible. It was found that the acoustic oscillations generation results in an appearance of the standing acoustic waves of the air pressure (density) in the IAF. In the case of the intensive blow of the air dust aerosol, it was demonstrated that the standing acoustic waves have some strong influences on both: 1) the dynamics of small dispersive coal dust particles movement and their accumulation in the IAF; 2) the oversaturation of the cylindrical coal granules by the adsorbed radioactive chemical elements and their isotopes in the regions, where the antin...

  9. Acoustic Fresnel lenses with extraordinary transmission

    Molerón, Miguel; Serra-Garcia, Marc; Daraio, Chiara

    2014-01-01

    We investigate numerically and experimentally highly efficient acoustic lenses based on the principle of extraordinary acoustic transmission. We study circular, flat lenses composed of perforated air channels. The geometry is similar to binary Fresnel lenses, and the lenses exploit several resonance mechanisms to enhance the transmission, such as Fabry–Perot resonances in the channels and cavity resonances on the lens surface. The proposed lenses are able to transmit up to 83% of the incident...

  10. 31P magnetic resonance spectroscopy of the Sherpa heart: a phosphocreatine/adenosine triphosphate signature of metabolic defense against hypobaric hypoxia.

    Hochachka, P W; Clark, C M; Holden, J E; Stanley, C; Ugurbil, K; Menon, R S

    1996-01-01

    Of all humans thus far studied, Sherpas are considered by many high-altitude biomedical scientists as most exquisitely adapted for life under continuous hypobaric hypoxia. However, little is known about how the heart is protected in hypoxia. Hypoxia defense mechanisms in the Sherpa heart were explored by in vivo, noninvasive 31P magnetic resonance spectroscopy. Six Sherpas were examined under two experimental conditions [normoxic (21% FiO2) and hypoxic (11% FiO2) and in two adaptational state...

  11. Determining Equilibrium Position For Acoustical Levitation

    Barmatz, M. B.; Aveni, G.; Putterman, S.; Rudnick, J.

    1989-01-01

    Equilibrium position and orientation of acoustically-levitated weightless object determined by calibration technique on Earth. From calibration data, possible to calculate equilibrium position and orientation in presence of Earth gravitation. Sample not levitated acoustically during calibration. Technique relies on Boltzmann-Ehrenfest adiabatic-invariance principle. One converts resonant-frequency-shift data into data on normalized acoustical potential energy. Minimum of energy occurs at equilibrium point. From gradients of acoustical potential energy, one calculates acoustical restoring force or torque on objects as function of deviation from equilibrium position or orientation.

  12. Stable And Oscillating Acoustic Levitation

    Barmatz, Martin B.; Garrett, Steven L.

    1988-01-01

    Sample stability or instability determined by levitating frequency. Degree of oscillation of acoustically levitated object along axis of levitation chamber controlled by varying frequency of acoustic driver for axis above or below frequency of corresponding chamber resonance. Stabilization/oscillation technique applied in normal Earth gravity, or in absence of gravity to bring object quickly to rest at nominal levitation position or make object oscillate in desired range about that position.

  13. Cylindrical acoustic levitator/concentrator

    Kaduchak, Gregory (Los Alamos, NM); Sinha, Dipen N. (Los Alamos, NM)

    2002-01-01

    A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.

  14. First images of thunder: Acoustic imaging of triggered lightning

    Dayeh, M. A.; Evans, N. D.; Fuselier, S. A.; Trevino, J.; Ramaekers, J.; Dwyer, J. R.; Lucia, R.; Rassoul, H. K.; Kotovsky, D. A.; Jordan, D. M.; Uman, M. A.

    2015-07-01

    An acoustic camera comprising a linear microphone array is used to image the thunder signature of triggered lightning. Measurements were taken at the International Center for Lightning Research and Testing in Camp Blanding, FL, during the summer of 2014. The array was positioned in an end-fire orientation thus enabling the peak acoustic reception pattern to be steered vertically with a frequency-dependent spatial resolution. On 14 July 2014, a lightning event with nine return strokes was successfully triggered. We present the first acoustic images of individual return strokes at high frequencies (>1 kHz) and compare the acoustically inferred profile with optical images. We find (i) a strong correlation between the return stroke peak current and the radiated acoustic pressure and (ii) an acoustic signature from an M component current pulse with an unusual fast rise time. These results show that acoustic imaging enables clear identification and quantification of thunder sources as a function of lightning channel altitude.

  15. Acoustical Imaging

    Litniewski, Jerzy; Kujawska, Tamara; 31st International Symposium on Acoustical Imaging

    2012-01-01

    The International Symposium on Acoustical Imaging is a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. This interdisciplinary Symposium has been taking place continuously since 1968. In the course of the years the proceedings volumes in the Acoustical Imaging Series have become a reference for cutting-edge research in the field. In 2011 the 31st International Symposium on Acoustical Imaging was held in Warsaw, Poland, April 10-13. Offering both a broad perspective on the state-of-the-art as well as  in-depth research contributions by the specialists in the field, this Volume 31 in the Series contains an excellent collection of papers in six major categories: Biological and Medical Imaging Physics and Mathematics of Acoustical Imaging Acoustic Microscopy Transducers and Arrays Nondestructive Evaluation and Industrial Applications Underwater Imaging

  16. Dynamic signatures method for analysis of vehicle-bridge resonance%动力指纹线方法在车桥共振分析中的应用

    张田; 夏禾; 郭薇薇

    2012-01-01

    铁路桥梁的动力行为(动挠度、动加速度)是桥上高速列车运行安全控制的重要指标之一。为此,基于列车动力指纹线和桥梁动力指纹线的概念,将列车激励简化为一组移动集中力,从理论上推导出了列车动力指纹线的数学表达式,提出了简支梁跨中竖向最大加速度的简化计算方法,据此得到车桥发生共振时列车速度,从而可以快速计算简支桥梁的动力行为。通过实例验证了文中方法的可行性,并分析了车桥共振的发生机理、影响参数,以及桥梁加速度计算时高频成分的影响。%The dynamic behavior of railway bridges (dynamic deflection and acceleration) is one of the running safety control indices for high-speed trains. Therefore, the dynamic behavior of railway bridges is studied based on the concept of the dynamic signatures of the train and the bridge. By simplifying the train excitation as a series of moving concentrated forces, the mathematical expressions of the dynamic signatures of the train are obtained through theoretical derivations, and then a method is presented for calculating the resonance speed of trains and the maximum vertical acceleration of the bridge. With this method, the dynamic responses of the simple supported bridge can be calculated quickly. The feasibility of this method is validated through some examples, in which the resonance mechanism of train-bridge system and the influencing factors are investigated. In addition, the effect of high frequency components to the bridge acceleration is also analyzed.

  17. Acoustic Transmitters for Underwater Neutrino Telescopes

    Ardid, Miguel; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D

    2012-01-01

    In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to...

  18. Case-study magnetic resonance imaging and acoustic investigation of the effects of vocal warm-up on two voice professionals

    Laukkanen, A. M.; Horáček, Jaromír; Havlík, R.

    2012-01-01

    Roč. 37, č. 2 (2012), s. 75-82. ISSN 1401-5439 R&D Projects: GA ČR GA101/08/1155 Institutional research plan: CEZ:AV0Z20760514 Keywords : speaker’s formant cluster * singer’s formant cluster * speech and singing training Subject RIV: BI - Acoustics Impact factor: 0.571, year: 2012

  19. Bayesian Extraction of Deep UV Resonance Raman Signature of Fibrillar Cross-β Sheet Core based on H-D Exchange Data

    Shashilov, V. A.; Lednev, I. K.

    2007-11-01

    Amyloid fibrils are associated with many neurodegenerative diseases. The application of conventional biophysical techniques including solution NMR and X-ray crystallography for structural characterization of fibrils is limited because they are neither crystalline nor soluble. The Bayesian approach was utilized for extracting the deep UV resonance Raman (DUVRR) spectrum of the lysozyme fibrillar β-sheet based on the hydrogen-deuterium exchange spectral data. The problem was shown to be unsolvable when using blind source separation or conventional chemometrics methods because of the 100% correlation of the concentration profiles of the species under study. Information about the mixing process was incorporated by forcing the columns of the concentration matrix to be proportional to the expected concentration profiles. The ill-conditioning of the matrix was removed by concatenating it to the diagonal matrix with entries corresponding to the known pure spectra (sources). Prior information about the spectral features and characteristic bands of the spectra was taken into account using the Bayesian signal dictionary approach. The extracted DUVRR spectrum of the cross-β sheet core exhibited sharp bands indicating the highly ordered structure. Well resolved sub-bands in Amide I and Amide III regions enabled us to assign the fibril core structure to anti-parallel β-sheet and estimate the amide group facial angle Ψ in the cross-β structure. The elaborated Bayesian approach was demonstrated to be applicable for studying correlated biochemical processes.

  20. Nonlinear interaction between acoustic gravity waves

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

    1996-01-01

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

  1. Radiation acoustics

    Lyamshev, Leonid M

    2004-01-01

    Radiation acoustics is a developing field lying at the intersection of acoustics, high-energy physics, nuclear physics, and condensed matter physics. Radiation Acoustics is among the first books to address this promising field of study, and the first to collect all of the most significant results achieved since research in this area began in earnest in the 1970s.The book begins by reviewing the data on elementary particles, absorption of penetrating radiation in a substance, and the mechanisms of acoustic radiation excitation. The next seven chapters present a theoretical treatment of thermoradiation sound generation in condensed media under the action of modulated penetrating radiation and radiation pulses. The author explores particular features of the acoustic fields of moving thermoradiation sound sources, sound excitation by single high-energy particles, and the efficiency and optimal conditions of thermoradiation sound generation. Experimental results follow the theoretical discussions, and these clearl...

  2. Application of transmission loss concept in the evaluation of an acoustic filter for liquid-borne transverse resonance modes in a duct of circular cross section

    Iwanicki, L. R.; Chang, Y. M.

    1980-01-01

    The transmission loss concept is used in the evaluation of an acoustic filter for liquid-borne transverse modes. Tests are conducted to determine the nature of filter element designs required to suppress transverse modes, to verify the presence of transverse modes in the test assembly, to define the acoustic wave incident, and to establish data recording, processing and analysis techniques providing transmission wave filter data. The first, second, and third tangential modes, and the first radial mode are found at frequencies of 2150, 3330, 4420, and 4110 Hz, respectively, and peaks of the tangential modes recede while the radial mode peak remains, demonstrating agreement with theoretical nodal patterns. The present design is found applicable to a liquid-oxygen system, and allows the easy-to-fabricate filter to fit within the available space envelope.

  3. Mathematical Modelling of the Sensitivity of Acoustic Resonance Properties to a Change in Volume of Lateral Cavities of the Human Vocal Tract

    Radolf, Vojtěch

    Praha: Institute of Theoretical and Applied Mechanics ASCR, v. v. i, 2015 - (Náprstek, J.; Fischer, C.). s. 248-249 ISBN 978-80-86246-42-0. ISSN 1805-8248. [Engineering mechanics 2015 /21./. 11.05.2015-14.05.2015, Svratka] R&D Projects: GA ČR GPP101/12/P579 Institutional support: RVO:61388998 Keywords : piriform sinus * vocal tract model * biomechanics of voice * formant frequency Subject RIV: BI - Acoustics

  4. In vivo measurements of air pressure, vocal folds vibration and acoustic characteristics of phonation into a straw and a resonance tube used in vocal exercising.

    Radolf, Vojtěch; Laukkanen, A. M.; Horáček, Jaromír; Veselý, Jan; Liu, D.

    Praha: Insitute of Thermomechanics ASCR, v. v. i., 2013 - (Zolotarev, I.). s. 127-128 ISBN 978-80-87012-46-8. ISSN 1805-8248. [Engineering Mechanics 2013 /19./. 13.05.2013-16.05.2013, Svratka] R&D Projects: GA ČR GPP101/12/P579 Institutional support: RVO:61388998 Keywords : biomechanics of voice * subglottal, oral and transglottal pressure * phonation into tubes Subject RIV: BI - Acoustics

  5. In vivo measurements of air pressure, vocal folds vibration and acoustic characteristics of phonation into a straw and a resonance tube used in vocal exercising.

    Radolf, Vojtěch; Laukkanen, A. M.; Horáček, Jaromír; Veselý, Jan; Liu, D.

    Prague: Institute of Thermomechanics, Academy of Sciences of the Czech Republic, v. v. i., 2013 - (Zolotarev, I.), s. 478-483 ISBN 978-80-87012-47-5. ISSN 1805-8256. [Engineering Mechanics 2013 /19./. Svratka (CZ), 13.05.2013-16.05.2013] R&D Projects: GA ČR GPP101/12/P579 Institutional support: RVO:61388998 Keywords : biomechanics of voice * subglottal, oral and transglottal pressure * phonation into tubes Subject RIV: BI - Acoustics

  6. Acoustic Mechanical Feedthroughs

    Sherrit, Stewart; Walkemeyer, Phillip; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea

    2013-01-01

    Electromagnetic motors can have problems when operating in extreme environments. In addition, if one needs to do mechanical work outside a structure, electrical feedthroughs are required to transport the electric power to drive the motor. In this paper, we present designs for driving rotary and linear motors by pumping stress waves across a structure or barrier. We accomplish this by designing a piezoelectric actuator on one side of the structure and a resonance structure that is matched to the piezoelectric resonance of the actuator on the other side. Typically, piezoelectric motors can be designed with high torques and lower speeds without the need for gears. One can also use other actuation materials such as electrostrictive, or magnetostrictive materials in a benign environment and transmit the power in acoustic form as a stress wave and actuate mechanisms that are external to the benign environment. This technology removes the need to perforate a structure and allows work to be done directly on the other side of a structure without the use of electrical feedthroughs, which can weaken the structure, pipe, or vessel. Acoustic energy is pumped as a stress wave at a set frequency or range of frequencies to produce rotary or linear motion in a structure. This method of transferring useful mechanical work across solid barriers by pumping acoustic energy through a resonant structure features the ability to transfer work (rotary or linear motion) across pressure or thermal barriers, or in a sterile environment, without generating contaminants. Reflectors in the wall of barriers can be designed to enhance the efficiency of the energy/power transmission. The method features the ability to produce a bi-directional driving mechanism using higher-mode resonances. There are a variety of applications where the presence of a motor is complicated by thermal or chemical environments that would be hostile to the motor components and reduce life and, in some instances, not be

  7. Battlefield acoustics

    Damarla, Thyagaraju

    2015-01-01

    This book presents all aspects of situational awareness in a battlefield using acoustic signals. It starts by presenting the science behind understanding and interpretation of sound signals. The book then goes on to provide various signal processing techniques used in acoustics to find the direction of sound source, localize gunfire, track vehicles, and detect people. The necessary mathematical background and various classification and fusion techniques are presented. The book contains majority of the things one would need to process acoustic signals for all aspects of situational awareness in one location. The book also presents array theory, which is pivotal in finding the direction of arrival of acoustic signals. In addition, the book presents techniques to fuse the information from multiple homogeneous/heterogeneous sensors for better detection. MATLAB code is provided for majority of the real application, which is a valuable resource in not only understanding the theory but readers, can also use the code...

  8. Acoustical Imaging

    Akiyama, Iwaki

    2009-01-01

    The 29th International Symposium on Acoustical Imaging was held in Shonan Village, Kanagawa, Japan, April 15-18, 2007. This interdisciplinary Symposium has been taking place every two years since 1968 and forms a unique forum for advanced research, covering new technologies, developments, methods and theories in all areas of acoustics. In the course of the years the volumes in the Acoustical Imaging Series have developed and become well-known and appreciated reference works. Offering both a broad perspective on the state-of-the-art in the field as well as an in-depth look at its leading edge research, this Volume 29 in the Series contains again an excellent collection of seventy papers presented in nine major categories: Strain Imaging Biological and Medical Applications Acoustic Microscopy Non-Destructive Evaluation and Industrial Applications Components and Systems Geophysics and Underwater Imaging Physics and Mathematics Medical Image Analysis FDTD method and Other Numerical Simulations Audience Researcher...

  9. Acoustic telemetry

    National Oceanic and Atmospheric Administration, Department of Commerce — To determine movements of green turtles in the nearshore foraging areas, we deployed acoustic tags and determined their movements through active and passive...

  10. Acoustics Research

    National Oceanic and Atmospheric Administration, Department of Commerce — Fisheries acoustics data are collected from more than 200 sea-days each year aboard the FRV DELAWARE II and FRV ALBATROSS IV (decommissioned) and the FSV Henry B....

  11. Cryogenic acoustic loss of pure and alloyed titanium

    Matacz, A. L.; Veitch, P. J.; Blair, D. G.

    Low acoustic loss, high yield strength cryogenic materials are required for various high precision experiments, resonant-bar gravitational radiation antennae in particular. We report here acoustic loss measurements of commerically pure and alloyed titanium samples between 4.2 and 300 K. It is shown that machining damage of the surface significantly increased the acoustic loss of pure titanium, particularly below 100 K, and that the high strength alloy Ti-6AI-4V had significantly greater acoustic loss than pure titanium.

  12. Human signatures in urban environments using low cost sensors

    Winston, Mark; Zong, Lei; Calcutt, Wade; Jones, Barry; Houser, Jeff

    2006-05-01

    McQ has produced a family of small (98 cm 3), inexpensive ($100), unattended ground sensors well suited for urban environments. As a result, a broad range of data has been collected in urban settings. This paper discusses human signatures in urban environments using low cost seismic, infrared, acoustic, and magnetic transducers. Transducer performance and the effects of orientation, building construction, and environmental noise will be focused on. Detection methods used to exploit signatures and resulting performance statistics will also be discussed.

  13. Interpreting underwater acoustic images of the upper ocean boundary layer

    A challenging task in physical studies of the upper ocean using underwater sound is the interpretation of high-resolution acoustic images. This paper covers a number of basic concepts necessary for undergraduate and postgraduate students to identify the most distinctive features of the images, providing a link with the acoustic signatures of physical processes occurring simultaneously beneath the surface of the sea. Sonars are so sensitive that they detected a new acoustic signature at the breaking of surface gravity waves in deep water, which resembles oblique motion-like vortices

  14. Acoustic levitation in the presence of gravity

    Collas, P.; Barmatz, M.; Shipley, C.

    1989-01-01

    The method of Gor'kov (1961) has been applied to derive general expressions for the total potential and force on a small spherical object in a resonant chamber in the presence of both acoustic and gravitational force fields. The levitation position is also determined in rectangular resonators for the simultaneous excitation of up to three acoustic modes, and the results are applied to the triple-axis acoustic levitator. The analysis is applied to rectangular, spherical, and cylindrical single-mode levitators that are arbitrarily oriented relative to the gravitational force field. Criteria are determined for isotropic force fields in rectangular and cylindrical resonators. It is demonstrated that an object will be situated within a volume of possible levitation positions at a point determined by the relative strength of the acoustic and gravitational fields and the orientation of the chamber relative to gravity.

  15. Techniques for Primary Acoustic Thermometry to 800 K

    Ripple, D. C.; Defibaugh, D. R.; Moldover, M. R.; Strouse, G. F.

    2003-09-01

    The NIST Primary Acoustic Thermometer will measure the difference between the International Temperature Scale of 1990 and the Kelvin Thermodynamic Scale throughout the range 273 K to 800 K with uncertainties of only a few millikelvins. The acoustic thermometer determines the frequencies of the acoustic resonances of pure argon gas contained within a spherical cavity with uncertainties approaching one part in 106. To achieve this small uncertainty at these elevated temperatures we developed new acoustic transducers and new techniques for the maintenance of gas purity and for temperature control. The new electro-acoustic transducers are based on the capacitance between a flexible silicon wafer and a rigid backing plate. Without the damping usually provided by polymers, mechanical vibrations caused unstable, spurious acoustic signals. We describe our techniques for suppression of these vibrations. Our acoustic thermometer allows the argon to be continuously flushed through the resonator, thereby preventing the build up of hydrogen that evolves from the stainless-steel resonator. We describe how the argon pressure is stabilized while flushing. The argon exiting from the resonator is analyzed with a customized gas chromatograph. Because the acoustic resonator was so large—it has an outer diameter of 20 cm—a sophisticated furnace, based on surrounding the resonator with three concentric aluminum shells, was designed to maintain thermal uniformity and stability of the resonator at a level of 1 mK. We describe the design, modeling, and operational characteristics of the furnace.

  16. Qualified Mobile Server Signature

    Orthacker, Clemens; Centner, Martin; Kittl, Christian

    2010-01-01

    International audience A legal basis for the use of electronic signatures exists since the introduction of qualified electronic signatures in EU Directive 1999/ 93/EC. Although considered as key enablers for e-Government and e-Commerce, qualified electronic signatures are still not widely used. Introducing amobile component addresses most of the shortcomings of existing qualified signature approaches but poses certain difficulties in the security reasoning. The proposed server based mobile...

  17. Efficient Threshold Signature Scheme

    Sattar J Aboud

    2012-01-01

    Full Text Available In this paper, we introduce a new threshold signature RSA-typed scheme. The proposed scheme has the characteristics of un-forgeable and robustness in random oracle model. Also, signature generation and verification is entirely non-interactive. In addition, the length of the entity signature participate is restricted by a steady times of the length of the RSA signature modulus. Also, the signing process of the proposed scheme is more efficient in terms of time complexity and interaction.

  18. Acoustically-Induced Electrical Signals

    Brown, S. R.

    2014-12-01

    We have observed electrical signals excited by and moving along with an acoustic pulse propagating in a sandstone sample. Using resonance we are now studying the characteristics of this acousto-electric signal and determining its origin and the controlling physical parameters. Four rock samples with a range of porosities, permeabilities, and mineralogies were chosen: Berea, Boise, and Colton sandstones and Austin Chalk. Pore water salinity was varied from deionized water to sea water. Ag-AgCl electrodes were attached to the sample and were interfaced to a 4-wire electrical resistivity system. Under computer control, the acoustic signals were excited and the electrical response was recorded. We see strong acoustically-induced electrical signals in all samples, with the magnitude of the effect for each rock getting stronger as we move from the 1st to the 3rd harmonics in resonance. Given a particular fluid salinity, each rock has its own distinct sensitivity in the induced electrical effect. For example at the 2nd harmonic, Berea Sandstone produces the largest electrical signal per acoustic power input even though Austin Chalk and Boise Sandstone tend to resonate with much larger amplitudes at the same harmonic. Two effects are potentially responsible for this acoustically-induced electrical response: one the co-seismic seismo-electric effect and the other a strain-induced resistivity change known as the acousto-electric effect. We have designed experimental tests to separate these mechanisms. The tests show that the seismo-electric effect is dominant in our studies. We note that these experiments are in a fluid viscosity dominated seismo-electric regime, leading to a simple interpretation of the signals where the electric potential developed is proportional to the local acceleration of the rock. Toward a test of this theory we have measured the local time-varying acoustic strain in our samples using a laser vibrometer.

  19. Acoustic emission

    This paper is related to our activities on acoustic emission (A.E.). The work is made with different materials: metals and fibre reinforced plastics. At present, acoustic emission transducers are being developed for low and high temperature. A test to detect electrical discharges in electrical transformers was performed. Our experience in industrial tests to detect cracks or failures in tanks or tubes is also described. The use of A.E. for leak detection is considered. Works on pattern recognition of A.E. signals are also being performed. (Author)

  20. Infra-sound Signature of Lightning

    Arechiga, R. O.; Badillo, E.; Johnson, J.; Edens, H. E.; Rison, W.; Thomas, R. J.

    2012-12-01

    We have analyzed thunder from over 200 lightning flashes to determine which part of thunder comes from the gas dynamic expansion of portions of the rapidly heated lightning channel and which from electrostatic field changes. Thunder signals were recorded by a ~1500 m network of 3 to 4 4-element microphone deployed in the Magdalena mountains of New Mexico in the summers of 2011 and 2012. The higher frequency infra-sound and audio-range portion of thunder is thought to come from the gas dynamic expansion, and the electrostatic mechanism gives rise to a signature infra-sound pulse peaked at a few Hz. More than 50 signature infra-sound pulses were observed in different portions of the thunder signal, with no preference towards the beginning or the end of the signal. Detection of the signature pulse occurs sometimes only for one array and sometimes for several arrays, which agrees with the theory that the pulse is highly directional (i.e., the recordings have to be in a specific position with respect to the cloud generating the pulse to be able to detect it). The detection of these pulses under quiet wind conditions by different acoustic arrays corroborates the electrostatic mechanism originally proposed by Wilson [1920], further studied by Dessler [1973] and Few [1985], observed by Bohannon [1983] and Balachandran [1979, 1983], and recently analyzed by Pasko [2009]. Pasko employed a model to explain the electrostatic-to-acoustic energy conversion and the initial compression waves in observed infrasonic pulses, which agrees with the observations we have made. We present thunder samples that exhibit signature infra-sound pulses at different times and acoustic source reconstruction to demonstrate the beaming effect.

  1. Quantum threshold group signature

    2008-01-01

    In most situations, the signer is generally a single person. However, when the message is written on behalf of an organization, a valid message may require the approval or consent of several persons. Threshold signature is a solution to this problem. Generally speaking, as an authority which can be trusted by all members does not exist, a threshold signature scheme without a trusted party appears more attractive. Following some ideas of the classical Shamir’s threshold signature scheme, a quantum threshold group signature one is proposed. In the proposed scheme, only t or more of n persons in the group can generate the group signature and any t-1 or fewer ones cannot do that. In the verification phase, any t or more of n signature receivers can verify the message and any t-1 or fewer receivers cannot verify the validity of the signature.

  2. Acoustic Transmitters for Underwater Neutrino Telescopes

    Carlos D. Llorens

    2012-03-01

    Full Text Available In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars, high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters.

  3. Extraordinary acoustic transmission through annuluses in air and its applications in acoustic beam splitter and concentrator.

    Ge, Yong; Sun, Hong-Xiang; Liu, Shu-Sen; Yuan, Shou-Qi; Xia, Jian-Ping; Guan, Yi-Jun; Zhang, Shu-Yi

    2016-08-01

    We report an extraordinary acoustic transmission through two layer annuluses made of metal cylinders in air both numerically and experimentally. The effect arises from the enhancement and reconstruction of the incident source induced by different Mie-resonance modes of the annuluses. The proposed system takes advantages of the consistency in the waveform between the input and output waves, the high amplitude amplification of output waves, and the easy adjustment of structure. More interestingly, we investigate the applications of the extraordinary acoustic transmission in the acoustic beam splitter and acoustic concentrator. Our finding should have an impact on ultrasonic applications. PMID:27587144

  4. Tunable acoustic waveguide based on vibro-acoustic metamaterials with shunted piezoelectric unit cells

    Kwon, Byung-Jin; Jung, Jin-Young; Lee, Dooho; Park, Kwang-Chun; Oh, Il-Kwon

    2015-10-01

    We propose a new class of acoustic waveguides with tunable bandgaps (TBs) by using vibro-acoustic metamaterials with shunted periodic piezoelectric unit cells. The unit metamaterial cells that consist of a single crystal piezoelectric transducer and an electrical shunt circuit are designed to induce a strong vibro-acousto-electrical coupling, resulting in a tunable acoustic bandgap as well as local structural resonance and Bragg scattering bandgaps. The present results show that the TB frequency can be actively controlled and the transmission loss of the acoustic wave can be greatly improved by simply changing the inductance values in the shunt circuit.

  5. Liquid rocket combustion chamber acoustic characterization

    Cândido Magno de Souza

    2010-09-01

    Full Text Available Over the last 40 years, many solid and liquid rocket motors have experienced combustion instabilities. Among other causes, there is the interaction of acoustic modes with the combustion and/or fluid dynamic processes inside the combustion chamber. Studies have been showing that, even if less than 1% of the available energy is diverted to an acoustic mode, combustion instability can be generated. On one hand, this instability can lead to ballistic pressure changes, couple with other propulsion systems such as guidance or thrust vector control, and in the worst case, cause motor structural failure. In this case, measures, applying acoustic techniques, must be taken to correct/minimize these influences on the combustion. The combustion chamber acoustic behavior in operating conditions can be estimated by considering its behavior in room conditions. In this way, acoustic tests can be easily performed, thus identifying the cavity modes. This paper describes the procedures to characterize the acoustic behavior in the inner cavity of four different configurations of a combustion chamber. Simple analytical models are used to calculate the acoustic resonance frequencies and these results are compared with acoustic natural frequencies measured at room conditions. Some comments about the measurement procedures are done, as well as the next steps for the continuity of this research. The analytical and experimental procedures results showed good agreement. However, limitations on high frequency band as well as in the identification of specific kinds of modes indicate that numerical methods able to model the real cavity geometry and an acoustic experimental modal analysis may be necessary for a more complete analysis. Future works shall also consider the presence of passive acoustic devices such as baffles and resonators capable of introducing damping and avoiding or limiting acoustic instabilities.

  6. Uncertainty in hydrological signatures

    Westerberg, I. K.; McMillan, H. K.

    2015-09-01

    Information about rainfall-runoff processes is essential for hydrological analyses, modelling and water-management applications. A hydrological, or diagnostic, signature quantifies such information from observed data as an index value. Signatures are widely used, e.g. for catchment classification, model calibration and change detection. Uncertainties in the observed data - including measurement inaccuracy and representativeness as well as errors relating to data management - propagate to the signature values and reduce their information content. Subjective choices in the calculation method are a further source of uncertainty. We review the uncertainties relevant to different signatures based on rainfall and flow data. We propose a generally applicable method to calculate these uncertainties based on Monte Carlo sampling and demonstrate it in two catchments for common signatures including rainfall-runoff thresholds, recession analysis and basic descriptive signatures of flow distribution and dynamics. Our intention is to contribute to awareness and knowledge of signature uncertainty, including typical sources, magnitude and methods for its assessment. We found that the uncertainties were often large (i.e. typical intervals of ±10-40 % relative uncertainty) and highly variable between signatures. There was greater uncertainty in signatures that use high-frequency responses, small data subsets, or subsets prone to measurement errors. There was lower uncertainty in signatures that use spatial or temporal averages. Some signatures were sensitive to particular uncertainty types such as rating-curve form. We found that signatures can be designed to be robust to some uncertainty sources. Signature uncertainties of the magnitudes we found have the potential to change the conclusions of hydrological and ecohydrological analyses, such as cross-catchment comparisons or inferences about dominant processes.

  7. On ULF Signatures of Lightning Discharges

    Bösinger, T.; Shalimov, S. L.

    2008-06-01

    Recent works on magnetic signatures due to distant lightning discharges are reviewed. Emphasis is laid on magnetic signatures in the ULF range (in the old definition from less than 1 mHz up to 1 Hz), that is in the frequency range below the Schumann resonance. These signatures are known to be of importance for the excitation of the ionospheric Alfvén resonator (IAR) which works only at night time conditions. This emphasizes the difference between night and day time ULF signatures of lightning. The IAR forms a link between the atmosphere and magnetosphere. Similarities and differences of this link in the VLF (Trimpi effect) and ULF range are worked out. A search for a unique signature of sprite-associated positive cloud-to-ground (+CG) lightning discharges ended with a negative result. In this context, however, a new model of lightning-associated induced mesospheric currents was built. Depending on mesospheric condition it can produce magnetic signatures in the entire frequency range from VLF, ELF to ULF. In the latter case it can explain signatures known as the Ultra Slow Tail of +CG lightning discharges. A current problem on the magnetic background noise intensity has been solved by taking more seriously the contribution of +CG lightning discharges to the overall background noise. Their low occurrence rate is more than compensated by their large and long lasting continuing currents. By superposed epoch analysis it could be shown that the ULF response to -CG is one to two orders smaller that in case of +CG with similar peak current values of the return stroke.

  8. MMW, IR, and SAM signature collection

    Reichstetter, Fred; Ward, Mary E.

    2002-08-01

    During the development of smart weapon's seeker/sensors, it is imperative to collect high quality signatures of the targets the system is intended to engage. These signatures are used to support algorithm development so the system can find and engage the targets of interest in the specific kill area on the target. Englin AFB FL is the AF development center for munitions; and in support of the development effort, the 46th Test Wing (46 TW) has initiated significant improvements in collection capabilities for signatures in the MMW, Infrared and Seismic, Acoustic and Magnetic (SAM) spectrum. Additionally, the Joint Munitions Test and Evaluation program office maintains a fleet of foreign ground vehicle targets used for such signature collection including items such as tanks, SCUD missile launchers, air defense units such as SA-06, SA-8, SA-13, and associated ground support trucks and general purpose vehicles. The major test facility includes a 300 ft tower used for mounting the instrumentation suite that currently includes, 10, 35 and 94 GHz MMW and 2-5(mu) and 8-12(mu) IR instrumentation systems. This facility has undergone major improvements in terms of background signature reduction, construction of a high bay building to house the turntable on which the targets are mounted, and an additional in- ground stationary turntable primarily for IR signature collection. Our experience using this facility to collect signatures for the smart weapons development community has confirmed a significant improvement in quality and efficiency. The need for the stationary turntable signature collection capability was driven by the requirements of the IR community who are interested in collecting signatures in clutter. This tends to be contrary to the MMW community that desires minimum background clutter. The resulting location, adjacent to the MMW tower, allows variations in the type and amount of clutter background that could be incorporated and also provides maximum utilization of

  9. Blind Collective Signature Protocol

    Nikolay A. Moldovyan

    2011-06-01

    Full Text Available Using the digital signature (DS scheme specified by Belarusian DS standard there are designed the collective and blind collective DS protocols. Signature formation is performed simultaneously by all of the assigned signers, therefore the proposed protocols can be used also as protocols for simultaneous signing a contract. The proposed blind collective DS protocol represents a particular implementation of the blind multisignature schemes that is a novel type of the signature schemes. The proposed protocols are the first implementations of the multisignature schemes based on Belarusian signature standard.

  10. Unconditionally Secure Quantum Signatures

    Ryan Amiri

    2015-08-01

    Full Text Available Signature schemes, proposed in 1976 by Diffie and Hellman, have become ubiquitous across modern communications. They allow for the exchange of messages from one sender to multiple recipients, with the guarantees that messages cannot be forged or tampered with and that messages also can be forwarded from one recipient to another without compromising their validity. Signatures are different from, but no less important than encryption, which ensures the privacy of a message. Commonly used signature protocols—signatures based on the Rivest–Adleman–Shamir (RSA algorithm, the digital signature algorithm (DSA, and the elliptic curve digital signature algorithm (ECDSA—are only computationally secure, similar to public key encryption methods. In fact, since these rely on the difficulty of finding discrete logarithms or factoring large primes, it is known that they will become completely insecure with the emergence of quantum computers. We may therefore see a shift towards signature protocols that will remain secure even in a post-quantum world. Ideally, such schemes would provide unconditional or information-theoretic security. In this paper, we aim to provide an accessible and comprehensive review of existing unconditionally securesecure signature schemes for signing classical messages, with a focus on unconditionally secure quantum signature schemes.

  11. Nonlinear acoustical properties of suspended sediment

    Kozhevnikova, I.; BjØrnØ, L.

    1994-01-01

    Maritime advances during recent years have shown the importance of and the need for development of ultrasonic methods for the investigation of the transport of suspended marine sediments in rivers and in coastal regions. Two main acoustical procedures have been developed and used for the investigations of suspended sediment qualities during the laboratory studies, (1) high frequency resonance backscattering and (2) attenuation acoustic spectroscopy. Both approaches are based on the same funda...

  12. Applied acoustics concepts, absorbers, and silencers for acoustical comfort and noise control alternative solutions, innovative tools, practical examples

    Fuchs, Helmut V

    2013-01-01

    The author gives a comprehensive overview of materials and components for noise control and acoustical comfort. Sound absorbers must meet acoustical and architectural requirements, which fibrous or porous material alone can meet. Basics and applications are demonstrated, with representative examples for spatial acoustics, free-field test facilities and canal linings. Acoustic engineers and construction professionals will find some new basic concepts and tools for developments in order to improve acoustical comfort. Interference absorbers, active resonators and micro-perforated absorbers of different materials and designs complete the list of applications.

  13. Acoustic lenses

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

  14. : FMRI in acoustic trauma sequelae

    Job, Agnès; Pons, Yoann; Lamalle, Laurent; Jaillard, Assia; Buck, Karl; Segebarth, Christoph; Delon-Martin, Chantal

    2012-01-01

    International audience The most common consequences of acute acoustic trauma (AAT) are hearing loss at frequencies above 3 kHz and tinnitus. In this study, we have used functional Magnetic Resonance Imaging (fMRI) to visualize neuronal activation patterns in military adults with AAT and various tinnitus sequelae during an auditory "oddball" attention task. AAT subjects displayed overactivities principally during reflex of target sound detection, in sensorimotor areas and in emotion-related...

  15. Material fabrication using acoustic radiation forces

    Sinha, Naveen N.; Sinha, Dipen N.; Goddard, Gregory Russ

    2015-12-01

    Apparatus and methods for using acoustic radiation forces to order particles suspended in a host liquid are described. The particles may range in size from nanometers to millimeters, and may have any shape. The suspension is placed in an acoustic resonator cavity, and acoustical energy is supplied thereto using acoustic transducers. The resulting pattern may be fixed by using a solidifiable host liquid, forming thereby a solid material. Patterns may be quickly generated; typical times ranging from a few seconds to a few minutes. In a one-dimensional arrangement, parallel layers of particles are formed. With two and three dimensional transducer arrangements, more complex particle configurations are possible since different standing-wave patterns may be generated in the resonator. Fabrication of periodic structures, such as metamaterials, having periods tunable by varying the frequency of the acoustic waves, on surfaces or in bulk volume using acoustic radiation forces, provides great flexibility in the creation of new materials. Periodicities may range from millimeters to sub-micron distances, covering a large portion of the range for optical and acoustical metamaterials.

  16. Acoustic Prism for Continuous Beam Steering Based on Piezoelectric Metamaterial

    Xu, Jiawen

    2016-01-01

    This paper investigates an acoustic prism for continuous acoustic beam steering by a simple frequency sweep. This idea takes advantages of acoustic wave velocity shifting in metamaterials in the vicinity of local resonance. We apply this concept into the piezoelectric metamaterial consisting of host medium and piezoelectric LC shunt. Theoretical modeling and FEM simulations are carried out. It is shown that the phase velocity of acoustic wave changes dramatically in the vicinity of local resonance. The directions of acoustic wave can be adjusted continuously between 2 to 16 degrees by a simple sweep of the excitation frequency. Such an electro-mechanical coupling system has a feature of adjusting local resonance without altering the mechanical part of the system.

  17. Fluorescent taggants with temporally coded signatures.

    Wang, Siyang; Vyas, Raul; Dwyer, Chris

    2016-07-11

    In this paper, resonance energy transfer (RET) networks between chromophores are used to implement fluorescent taggants with temporally coded signatures. Because the temporal signature of such a fluorescent taggant is a phase-type distribution defined by the geometry of its RET network, the taggant design is not constrained by resolvable dyes and has a significantly larger coding capacity than spectrally or lifetime coded fluorescent taggants. Meanwhile, the detection process becomes highly efficient when the signatures are coded in the time domain. The taggant identification method is based on the multinomial distribution of detected photons and Maximum Likelihood Estimation, which guarantees high accuracy even with only a few hundred photons and also applies to a mixture of taggants in multiplex detection. Therefore, these temporally coded fluorescent taggants have great potential for both in situ and Lidar applications. PMID:27410827

  18. Double-negative flexural acoustic metamaterial

    We present an acoustic metamaterial for flexural waves with both negative density and elastic modulus. By means of an analytical lumped-element approach, we introduce a combination of resonant elements on the surface of a plate. Following on from experimental demonstrations and theoretical work, negative density is achieved by introducing elements such as stubs that involve normal-force interactions, whereas negative modulus is achieved by introducing new types of resonant element that involve lateral forces and rotational inertia. Our approach therefore opens the way for the realization of double-negative acoustic meta-plates to control flexural waves. Applications include cloaking and filtering. (paper)

  19. Compressibility-near-zero acoustic metamaterial

    This letter theoretically analyzes and experimentally demonstrates a novel class of compressibility-near-zero (CNZ) acoustic metamaterials, achieved by using resonant-type metamaterials, namely the Helmholtz resonator. We first present a closed analytical formula for the effective compressibility of the proposed unit cell and then show that two frequencies exist which may support CNZ propagation. We demonstrate how the choice of the actual operating CNZ frequency depends on the properties of the host and finally experimentally verify CNZ propagation of acoustic waves.

  20. Compressibility-near-zero acoustic metamaterial

    Cselyuszka, Norbert, E-mail: cselyu@yahoo.com; Sečujski, Milan, E-mail: secujski@uns.ac.rs; Crnojević Bengin, Vesna, E-mail: bengin@uns.ac.rs

    2014-03-01

    This letter theoretically analyzes and experimentally demonstrates a novel class of compressibility-near-zero (CNZ) acoustic metamaterials, achieved by using resonant-type metamaterials, namely the Helmholtz resonator. We first present a closed analytical formula for the effective compressibility of the proposed unit cell and then show that two frequencies exist which may support CNZ propagation. We demonstrate how the choice of the actual operating CNZ frequency depends on the properties of the host and finally experimentally verify CNZ propagation of acoustic waves.

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

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

    2016-03-01

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

  2. Metamaterial based embedded acoustic filters for structural applications

    Hongfei Zhu; Fabio Semperlotti

    2013-01-01

    We investigate the use of acoustic metamaterials to design structural materials with frequency selective characteristics. By exploiting the properties of acoustic metamaterials, we tailor the propagation characteristics of the host structure to effectively filter the constitutive harmonics of an incoming broadband excitation. The design approach exploits the characteristics of acoustic waveguides coupled by cavity modes. By properly designing the cavity we can tune the corresponding resonant ...

  3. Ultrasonic Doppler methods to extract signatures of a walking human.

    Mehmood, Asif; Sabatier, James M; Damarla, Thyagaraju

    2012-09-01

    Extraction of Doppler signatures that characterize human motion has attracted a growing interest in recent years. These Doppler signatures are generated by various components of the human body while walking, and contain unique features that can be used for human detection and recognition. Although, a significant amount of research has been done in radio frequency regime for human Doppler signature extraction, considerably less has been done in acoustics. In this work, 40 kHz ultrasonic sonar is employed to measure the Doppler signature generated by the motion of body segments using different electronic and signal processing schemes. These schemes are based on both analog and digital demodulation with homodyne and heterodyne receiver circuitry. The results and analyses from these different schemes are presented. PMID:22979839

  4. Surface Acoustic Wave Devices

    Dühring, Maria Bayard

    The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...... application is modulation of optical waves in waveguides. This presentation elaborates on how a SAW is generated by interdigital transducers using a 2D model of a piezoelectric, inhomogeneous material implemented in the high-level programming language Comsol Multiphysics. The SAW is send through a model of a...... output waveguide and the MZI can thus be used as an optical switch. It is explained how the mechanical model of the SAW is coupled to a model of the optical waves such that the change in effective refractive index introduced in the MZI arms by the SAW can be calculated. Results of a parameter study of...

  5. Infrared signatures for remote sensing

    PNL's capabilities for infrared and near-infrared spectroscopy include tunable-diode-laser (TDL) systems covering 300--3,000 cm-1 at 2 laser. PNL also has a beam expansion source with a 12-cm slit, which provides a 3-m effective path for gases at ∼10 K, giving a Doppler width of typically 10 MHz; and long-path static gas cells (to 100 m). In applying this equipment to signatures work, the authors emphasize the importance of high spectral resolution for detecting and identifying atmospheric interferences; for identifying the optimum analytical frequencies; for deriving, by spectroscopic analysis, the molecular parameters needed for modeling; and for obtaining data on species and/or bands that are not in existing databases. As an example of such spectroscopy, the authors have assigned and analyzed the C-Cl stretching region of CCl4 at 770--800 cm-1. This is an important potential signature species whose IR absorption has remained puzzling because of the natural isotopic mix, extensive hot-band structure, and a Fermi resonance involving a nearby combination band. Instrument development projects include the IR sniffer, a small high-sensitivity, high-discrimination (Doppler-limited) device for fence-line or downwind monitoring that is effective even in regions of atmospheric absorption; preliminary work has achieved sensitivities at the low-ppb level. Other work covers trace species detection with TDLs, and FM-modulated CO2 laser LIDAR. The authors are planning a field experiment to interrogate the Hanford tank farm for signature species from Rattlesnake Mountain, a standoff of ca. 15 km, to be accompanied by simultaneous ground-truthing at the tanks

  6. Machine Fault Signature Analysis

    K. B. Mulchandani

    2008-03-01

    Full Text Available The objective of this paper is to present recent developments in the field of machine fault signature analysis with particular regard to vibration analysis. The different types of faults that can be identified from the vibration signature analysis are, for example, gear fault, rolling contact bearing fault, journal bearing fault, flexible coupling faults, and electrical machine fault. It is not the intention of the authors to attempt to provide a detailed coverage of all the faults while detailed consideration is given to the subject of the rolling element bearing fault signature analysis.

  7. Holographic acoustic elements for manipulation of levitated objects

    Marzo, Asier; Seah, Sue Ann; Drinkwater, Bruce W.; Sahoo, Deepak Ranjan; Long, Benjamin; Subramanian, Sriram

    2015-10-01

    Sound can levitate objects of different sizes and materials through air, water and tissue. This allows us to manipulate cells, liquids, compounds or living things without touching or contaminating them. However, acoustic levitation has required the targets to be enclosed with acoustic elements or had limited manoeuvrability. Here we optimize the phases used to drive an ultrasonic phased array and show that acoustic levitation can be employed to translate, rotate and manipulate particles using even a single-sided emitter. Furthermore, we introduce the holographic acoustic elements framework that permits the rapid generation of traps and provides a bridge between optical and acoustical trapping. Acoustic structures shaped as tweezers, twisters or bottles emerge as the optimum mechanisms for tractor beams or containerless transportation. Single-beam levitation could manipulate particles inside our body for applications in targeted drug delivery or acoustically controlled micro-machines that do not interfere with magnetic resonance imaging.

  8. Acoustic transparency and opacity using Fano Interferences in Metamaterials

    Khelif, A.

    2015-08-04

    We investigate both experimentally and theoretically how to generate the acoustical analogue of the Electromagnetically Induced Transparency. This phenomenon arises from Fano resonances originating from constructive and destructive interferences of a narrow discrete resonance with a broad spectral line or continuum. Measurements were realized on a double-cavity structure by using a Kundt’s Tube. Transmission properties reveal an asymmetric lineshape of the transmission that leads to acoustic transparency.

  9. The Frequency Characteristics Simulation of Traveling Wave Thermo-Acoustic Engine

    Ma Lili; Xia Jiakuan; Guo Tie

    2013-01-01

    The frequency characteristics of thermo-acoustic engine mainly depend on the internal working medium and device structure. The linear resonant system is consisted of ironless permanent magnet linear synchronous motor and the resonant spring. Through the analysis of thermo-acoustic power generation system model, the parameters of linear resonant system are determined by building a mathematical model of linear resonant system. Combined with modern control theory and robust control theory, a rob...

  10. Acoustic and microwave tests in a cylindrical cavity for acoustic gas thermometry at high temperature.

    Zhang, K; Feng, X J; Gillis, K; Moldover, M; Zhang, J T; Lin, H; Qu, J F; Duan, Y N

    2016-03-28

    Relative primary acoustic gas thermometry (AGT) determines the ratios of thermodynamic temperatures from measured ratios of acoustic and microwave resonance frequencies in a gas-filled metal cavity on isotherms of interest. When measured in a cavity with known dimensions, the frequencies of acoustic resonances in a gas determine the speed of sound, which is a known function of the thermodynamic temperature T. Changes in the dimensions of the cavity are measured using the frequencies of the cavity's microwave resonances. We explored techniques and materials for AGT at high temperatures using a cylindrical cavity with remote acoustic transducers. We used gas-filled ducts as acoustic waveguides to transmit sound between the cavity at high temperatures and the acoustic transducers at room temperature. We measured non-degenerate acoustic modes in a cylindrical cavity in the range 295 Kacoustic frequencies increased from 2×10(-6) at 295 K to 5×10(-6) at 797 K. In addition, we measured the frequencies of several transverse magnetic (TM) microwave resonances up to 1000 K in order to track changes in the cavity's length L and radius R. The fractional standard deviation of the values of L deduced from three TM modes increased from 3×10(-6) for T<600 K to 57 × 10(-6) at 1000 K. We observed similar inconsistencies in a previous study. PMID:26903106

  11. Are there molecular signatures?

    Bennett, W.P.

    1995-10-01

    This report describes molecular signatures and mutational spectrum analysis. The mutation spectrum is defined as the type and location of DNA base change. There are currently about five well documented cases. Mutations and radon-associated tumors are discussed.

  12. Advanced Missile Signature Center

    Federal Laboratory Consortium — The Advanced Missile Signature Center (AMSC) is a national facility supporting the Missile Defense Agency (MDA) and other DoD programs and customers with analysis,...

  13. THE ELECTRONIC SIGNATURE

    Voiculescu Madalina Irena; Gramada Dragu Argentina

    2009-01-01

    Article refers to significance and the digital signature in electronic commerce. Internet and electronic commerce open up many new opportunities for the consumer, yet, the security (or perceived lack of security) of exchanging personal and financial data

  14. Design and Experimental Applications of Acoustic Metamaterials

    Zigoneanu, Lucian

    Acoustic metamaterials are engineered materials that were extensively investigated over the last years mainly because they promise properties otherwise hard or impossible to find in nature. Consequently, they open the door for improved or completely new applications (e.g. acoustic superlens that can exceed the diffraction limit in imaging or acoustic absorbing panels with higher transmission loss and smaller thickness than regular absorbers). Our objective is to surpass the limited frequency operating range imposed by the resonant mechanism that s1ome of these materials have. In addition, we want acoustic metamaterials that could be experimentally demonstrated and used to build devices with overall performances better than the previous ones reported in the literature. Here, we start by focusing on the need of engineered metamaterials in general and acoustic metamaterials in particular. Also, the similarities between electromagnetic metamaterials and acoustic metamaterials and possible ways to realize broadband acoustic metamaterials are briefly discussed. Then, we present the experimental realization and characterization of a two-dimensional (2D) broadband acoustic metamaterial with strongly anisotropic effective mass density. We use this metamaterial to realize a 2D broadband gradient index acoustic lens in air. Furthermore, we optimize the lens design by improving each unit cell's performance and we also realize a 2D acoustic ground cloak in air. In addition, we explore the performance of some novel applications (a 2D acoustic black hole and a three-dimensional acoustic cloak) using the currently available acoustic metamaterials. In order to overcome the limitations of our designs, we approach the active acoustic metamaterials path, which offers a broader range for the material parameters values and a better control over them. We propose two structures which contain a sensing element (microphone) and an acoustic driver (piezoelectric membrane or speaker). The

  15. Meteor signature interpretation

    Canavan, G.H.

    1997-01-01

    Meteor signatures contain information about the constituents of space debris and present potential false alarms to early warnings systems. Better models could both extract the maximum scientific information possible and reduce their danger. Accurate predictions can be produced by models of modest complexity, which can be inverted to predict the sizes, compositions, and trajectories of object from their signatures for most objects of interest and concern.

  16. Stateless Transitive Signature Schemes

    MA Chun-guang; CAI Man-chun; YANG Yi-xian

    2004-01-01

    A new practical method is introduced to transform the stateful transitive signature scheme to stateless one without the loss of security. According to the approach, two concrete stateless transitive signature schemes based on Factoring and RSA are presented respectively. Under the assumption of the hardness of factoring and one-more- RSA-inversion problem, both two schemes are secure under the adaptive chosen-message attacks in random oracle model.

  17. Machine Fault Signature Analysis

    Mulchandani, K. B.; A.K. Wadhwani; Pratesh Jayaswal

    2008-01-01

    The objective of this paper is to present recent developments in the field of machine fault signature analysis with particular regard to vibration analysis. The different types of faults that can be identified from the vibration signature analysis are, for example, gear fault, rolling contact bearing fault, journal bearing fault, flexible coupling faults, and electrical machine fault. It is not the intention of the authors to attempt to provide a detailed coverage of all the faults while deta...

  18. Acoustic hemostasis

    Crum, L.; Andrew, M.; Bailey, M.; Beach, K.; Brayman, A.; Curra, F.; Kaczkowski, P.; Kargl, S.; Martin, R.; Vaezy, S.

    2003-04-01

    Over the past several years, the Center for Industrial and Medical Ultrasound (CIMU) at the Applied Physics Laboratory in the University of Washington has undertaken a broad research program in the general area of High Intensity Focused Ultrasound (HIFU). Our principal emphasis has been on the use of HIFU to induce hemostasis; in particular, CIMU has sought to develop a small, lightweight, portable device that would use ultrasound for both imaging and therapy. Such a technology is needed because nearly 50% of combat casualty mortality results from exsanguinations, or uncontrolled bleeding. A similar percentage occurs for civilian death due to trauma. In this general review, a presentation of the general problem will be given, as well as our recent approaches to the development of an image-guided, transcutaneous, acoustic hemostasis device. [Work supported in part by the USAMRMC, ONR and the NIH.

  19. Acoustic telemetry.

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

    Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

  20. Acoustic Neuroma Educational Video

    Full Text Available Educational Video Home What is an AN What is an Acoustic Neuroma? Identifying an AN Symptoms Acoustic Neuroma Keywords Educational Video ... for pre- and post-treatment acoustic neuroma patients. Home What is an AN What is an Acoustic ...

  1. Flow noise source-resonator coupling

    This paper investigates the coupling mechanism between flow noise sources and acoustic resonators. Analytical solutions are developed for the classical cases of monopole and dipole types of flow noise sources. The effectiveness of the coupling between the acoustic resonator and the noise source is shown to be dependent on the type of noise source as well as its location on the acoustic pressure mode shape. For a monopole source, the maximum coupling occurs when the noise source is most intense near an acoustic pressure antinode (i.e., location of maximum acoustic pressure). A numerical study with the impedance method demonstrates this effect. A dipole source couples most effectively when located near an acoustic pressure node

  2. Use of acoustic vortices in acoustic levitation

    Cutanda Henriquez, Vicente; Santillan, Arturo Orozco; Juhl, Peter Møller

    2009-01-01

    Acoustic fields are known to exert forces on the surfaces of objects. These forces are noticeable if the sound pressure is sufficiently high. Two phenomena where acoustic forces are relevant are: i) acoustic levitation, where strong standing waves can hold small objects at certain positions...... of acoustical vortices uses an efficient numerical implementation based on the superposition of two orthogonal sound fields with a delay of 90° between them. It is shown that acoustic levitation and the use of acoustic vortices can be combined to manipulate objects in an efficient and controlled manner without......, counterbalancing their weight, and ii) acoustic vortices, spinning sound fields that can impinge angular momentum and cause rotation of objects. In this contribution, both force-creating sound fields are studied by means of numerical simulations. The Boundary Element Method is employed to this end. The simulation...

  3. Potential Competitive Dynamics of Acoustic Ecology.

    Radford, C A; Montgomery, J C

    2016-01-01

    The top predators in coastal marine ecosystems, such as whales, dolphins, seabirds, and large predatory fishes (including sharks), may compete with each other to exploit food aggregations. Finding these patchy food sources and being first to a food patch could provide a significant competitive advantage. Our hypothesis is that food patches have specific sound signatures that marine predators could detect and that acoustic sources and animal sensory capabilities may contribute to competition dynamics. Preliminary analysis shows that diving gannets have a distinct spectral signature between 80 and 200 Hz, which falls within the hearing sensitivity of large pelagic fishes. Therefore, we suggest that diving birds may contribute to the sound signatures of food aggregations, linking competition dynamics both above and below the water surface. PMID:26611047

  4. Interference-induced angle-independent acoustical transparency

    It is revealed that the Fano-like interference leads to the extraordinary acoustic transmission through a slab metamaterial of thickness much smaller than the wavelength, with each unit cell consisting of a Helmholtz resonator and a narrow subwavelength slit. More importantly, both the theoretical analysis and experimental measurement show that the angle-independent acoustical transparency can be realized by grafting a Helmholtz resonator and a quarter-wave resonator to the wall of a narrow subwavelength slit in each unit cell of a slit array. The observed phenomenon results from the interferences between the waves propagating in the slit, those re-radiated by the Helmholtz resonator, and those re-radiated by the quarter-wave resonator. The proposed design may find its applications in designing angle-independent acoustical filters and controlling the phase of the transmitted waves

  5. Interference-induced angle-independent acoustical transparency

    Qi, Lehua; Yu, Gaokun, E-mail: gkyu@ouc.edu.cn; Wang, Ning [Department of Marine Technology, Ocean University of China, Qingdao 266100 (China); Wang, Xinlong [Key Laboratory of Modern Acoustics and Institute of Acoustics, Nanjing University, Nanjing 210093 (China); Wang, Guibo [Shipbuilding Information Center of China, Beijing 100012 (China)

    2014-12-21

    It is revealed that the Fano-like interference leads to the extraordinary acoustic transmission through a slab metamaterial of thickness much smaller than the wavelength, with each unit cell consisting of a Helmholtz resonator and a narrow subwavelength slit. More importantly, both the theoretical analysis and experimental measurement show that the angle-independent acoustical transparency can be realized by grafting a Helmholtz resonator and a quarter-wave resonator to the wall of a narrow subwavelength slit in each unit cell of a slit array. The observed phenomenon results from the interferences between the waves propagating in the slit, those re-radiated by the Helmholtz resonator, and those re-radiated by the quarter-wave resonator. The proposed design may find its applications in designing angle-independent acoustical filters and controlling the phase of the transmitted waves.

  6. Acoustic signal analysis of underwater elastic cylinder

    LI Xiukun; YANG Shi'e

    2001-01-01

    The echoes of underwater elastic cylinder comprise two types of acoustic components: Geometrical scattering waves and elastic scattering waves. The transfer function is appropriate to characterize the echo of targets. And the discrete wavelet transform of amplitude spectrum is presented and used to identify the resonant components of underwater targets.PACS numbers: 43.30, 43.60

  7. Continuous acoustic separation in a thermoplastic microchannel

    Acoustic manipulation of particles and cells has been widely used for trapping and separation in microfluidic devices. Previously, the resonant components of these devices have been fabricated from silicon, glass, metals, or other materials having high acoustic impedance. Here, we present experimental results showing continuous acoustic focusing and separation of blood cells in a microchannel fabricated entirely from polystyrene. The efficiency and flow rates approach those reported in silicon and glass systems. We find that the optimum operating frequencies differ from those predicted by conventional approximations which have been developed for more rigid materials. Additionally, we introduce a method for fabrication of the devices, using an adaptation of thermofusion bonding that preserves critical channel dimensions. To control channel cross section during bonding, we introduced a collapsible fiberboard material in the bonding press. This structure provided a self-limiting force and mitigated deformation of the polystyrene. Together, these advances may enable new applications for acoustic focusing and separation in medical devices. (paper)

  8. Acoustic dispersive prism

    Hussein Esfahlani; Sami Karkar; Herve Lissek; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic ...

  9. Theory for the Acoustic Raman Modes of Proteins

    DeWolf, Timothy

    2016-01-01

    We present a theoretical analysis that associates the resonances of extraordinary acoustic Raman (EAR) spectroscopy [Wheaton et al., Nat Photon 9, 68 (2015)] with the collective modes of proteins. The theory uses the anisotropic elastic network model to find the protein acoustic modes, and calculates Raman intensity by treating the protein as a polarizable ellipsoid. Reasonable agreement is found between EAR spectra and our theory. Protein acoustic modes have been extensively studied theoretically to assess the role they play in protein function; this result suggests EAR as a new experimental tool for studies of protein acoustic modes.

  10. Spectroscopic Signatures Related to a Sunquake

    Matthews, Sarah A; Zharkov, Sergei; Green, Lucie M

    2015-01-01

    The presence of flare related acoustic emission (sunquakes) in some flares represents a severe challenge to our current understanding of flare energy transport processes. We present a comparison of new spectral observations from Hinode's EUV imaging Spectrometer (EIS) and the Interface Region Imaging Spectrograph (IRIS) of the atmosphere above a sunquake, and compare them to the spectra observed in a part of the flaring region with no acoustic signature. Evidence for the sunquake is determined using both time-distance and acoustic holography methods, and we find that, unlike many previous sunquake detections, the signal is rather dispersed, but that the time-distance and 6 and 7 mHz sources converge at the same spatial location. We also see some evidence for different evolution at different frequencies, with an earlier peak at 7 mHz than at 6 mHz. Using spectroscopic measurements we find that in this location at the time of the 7 mHz peak the spectral emission is significantly more intense, shows larger veloc...

  11. Negative refraction imaging of acoustic metamaterial lens in the supersonic range

    Jianning Han; Tingdun Wen; Peng Yang; Lu Zhang

    2014-01-01

    Acoustic metamaterials with negative refraction index is the most promising method to overcome the diffraction limit of acoustic imaging to achieve ultrahigh resolution. In this paper, we use localized resonant phononic crystal as the unit cell to construct the acoustic negative refraction lens. Based on the vibration model of the phononic crystal, negative quality parameters of the lens are obtained while excited near the system resonance frequency. Simulation results show that negative refr...

  12. Broadband Acoustic Liner Optimization Study Using Novel Poro-elastic Materials

    Mitchell, Kelsey Ryan

    2015-01-01

    With the continual challenges associated with reducing aircraft engine noise, there is need for acoustic liner configurations that target broadband performance. This thesis experimentally and analytically investigates passive noise control methods to improve broadband frequency attenuation through various acoustic liner designs. The inclusion of acoustic metamaterials within these liners is examined and optimized. The metamaterials studied consist of resonant and non-resonant materials which ...

  13. Reading the Signatures of Extrasolar Planets in Debris Disks

    Kuchner, Marc J.

    2009-01-01

    An extrasolar planet sculpts the famous debris dish around Fomalhaut; probably ma ny other debris disks contain planets that we could locate if only we could better recognize their signatures in the dust that surrounds them. But the interaction between planets and debris disks involves both orbital resonances and collisions among grains and rocks in the disks --- difficult processes to model simultanemus]y. I will describe new 3-D models of debris disk dynamics that incorporate both collisions and resonant trapping of dust for the first time, allowing us to decode debris disk images and read the signatures of the planets they contain.

  14. Theoretical and experimental verification of acoustic focusing in metal cylinder structure

    Xia, Jian-ping; Sun, Hong-xiang; Cheng, Qian; Xu, Zheng; Chen, Hao; Yuan, Shou-qi; Zhang, Shu-yi; Ge, Yong; Guan, Yi-jun

    2016-05-01

    We report the realization of a multifocal acoustic focusing lens using a simple metal cylinder structure immersed in water, as determined both experimentally and theoretically. The acoustic waves can be focused on one or more points, because the Mie-resonance modes are excited in the cylinder structure. The acoustic pressure fields measured in the Schlieren imaging system agree with the results calculated using the acoustic scattering theory. Interesting applications of multifocal focusing in the acoustic encryption communication are further discussed. Our work should be helpful in understanding the focusing mechanism and experimentally measuring the acoustic phenomena in cylinder structures.

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

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

    2014-10-01

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

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

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

    2014-10-15

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

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

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

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope. PMID:25362441

  18. Soft 3D acoustic metamaterial with negative index.

    Brunet, Thomas; Merlin, Aurore; Mascaro, Benoit; Zimny, Kevin; Leng, Jacques; Poncelet, Olivier; Aristégui, Christophe; Mondain-Monval, Olivier

    2015-04-01

    Many efforts have been devoted to the design and achievement of negative-refractive-index metamaterials since the 2000s. One of the challenges at present is to extend that field beyond electromagnetism by realizing three-dimensional (3D) media with negative acoustic indices. We report a new class of locally resonant ultrasonic metafluids consisting of a concentrated suspension of macroporous microbeads engineered using soft-matter techniques. The propagation of Gaussian pulses within these random distributions of 'ultra-slow' Mie resonators is investigated through in situ ultrasonic experiments. The real part of the acoustic index is shown to be negative (up to almost - 1) over broad frequency bandwidths, depending on the volume fraction of the microbeads as predicted by multiple-scattering calculations. These soft 3D acoustic metamaterials open the way for key applications such as sub-wavelength imaging and transformation acoustics, which require the production of acoustic devices with negative or zero-valued indices. PMID:25502100

  19. Soft 3D acoustic metamaterial with negative index

    Brunet, Thomas; Merlin, Aurore; Mascaro, Benoit; Zimny, Kevin; Leng, Jacques; Poncelet, Olivier; Aristégui, Christophe; Mondain-Monval, Olivier

    2015-04-01

    Many efforts have been devoted to the design and achievement of negative-refractive-index metamaterials since the 2000s. One of the challenges at present is to extend that field beyond electromagnetism by realizing three-dimensional (3D) media with negative acoustic indices. We report a new class of locally resonant ultrasonic metafluids consisting of a concentrated suspension of macroporous microbeads engineered using soft-matter techniques. The propagation of Gaussian pulses within these random distributions of ‘ultra-slow’ Mie resonators is investigated through in situ ultrasonic experiments. The real part of the acoustic index is shown to be negative (up to almost - 1) over broad frequency bandwidths, depending on the volume fraction of the microbeads as predicted by multiple-scattering calculations. These soft 3D acoustic metamaterials open the way for key applications such as sub-wavelength imaging and transformation acoustics, which require the production of acoustic devices with negative or zero-valued indices.

  20. Actions for signature change

    Embacher, F

    1995-01-01

    This is a contribution on the controversy about junction conditions for classical signature change. The central issue in this debate is whether the extrinsic curvature on slices near the hypersurface of signature change has to be continuous ({\\it weak} signature change) or to vanish ({\\it strong} signature change). Led by a Lagrangian point of view, we write down eight candidate action functionals S_1,...S_8 as possible generalizations of general relativity and investigate to what extent each of these defines a sensible variational problem, and which junction condition is implied. Four of the actions involve an integration over the total manifold. A particular subtlety arises from the precise definition of the Einstein-Hilbert Lagrangian density |g|^{1/2} R[g]. The other four actions are constructed as sums of integrals over singe-signature domains. The result is that {\\it both} types of junction conditions occur in different models, i.e. are based on different first principles, none of which can be claimed t...

  1. NATO TG-53: acoustic detection of weapon firing joint field experiment

    Robertson, Dale N.; Pham, Tien; Scanlon, Michael V.; Srour, Nassy; Reiff, Christian G.; Sim, Leng K.; Solomon, Latasha; Thompson, Dorothea F.

    2006-05-01

    In this paper, we discuss the NATO Task Group 53 (TG-53) acoustic detection of weapon firing field joint experiment at Yuma Proving Ground during 31 October to 4 November 2005. The participating NATO countries include France, the Netherlands, UK and US. The objectives of the joint experiments are: (i) to collect acoustic signatures of direct and indirect firings from weapons such as sniper, mortar, artillery and C4 explosives and (ii) to share signatures among NATO partners from a variety of acoustic sensing platforms on the ground and in the air distributed over a wide area.

  2. HYbriD Resonant Acoustics (HYDRA).

    Rezk, Amgad R; Tan, James K; Yeo, Leslie Y

    2016-03-01

    The existence of what is termed here as a surface-reflected bulk wave is unraveled and elucidated, and it is shown, quite counterintuitively, that it is possible to obtain an order-of-magnitude improvement in microfluidic manipulation efficiency, and, in particular, nebulization, through a unique combination of surface and bulk waves without increasing complexity or cost. PMID:26743122

  3. Seismic signatures of partial saturation on acoustic borehole modes

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

    2007-01-01

    We present an exact theory of attenuation and dispersion of borehole Stoneley waves propagating along porous rocks containing spherical gas bubbles by using the Biot theory. An effective frequency-dependent fluid bulk modulus is introduced to describe the dynamic (oscillatory) behavior of the gas bu

  4. Quantum signature of analog Hawking radiation in momentum space

    Boiron, D.; Fabbri, A.; Larré, P. -É.; Pavloff, N; Westbrook, C. I.; Ziń, P.

    2014-01-01

    We consider a sonic analog of a black hole realized in the one-dimensional flow of a Bose-Einstein condensate. Our theoretical analysis demonstrates that one- and two-body momentum distributions accessible by present-day experimental techniques provide clear direct evidence (i) of the occurrence of a sonic horizon, (ii) of the associated acoustic Hawking radiation and (iii) of the quantum nature of the Hawking process. The signature of the quantum behavior persists even at temperatures larger...

  5. Acoustic Neurinomas

    Mohammad Faraji Rad

    2011-01-01

    Full Text Available Acoustic neuromas (AN are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(VS causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumor is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few. The predominant clinical endpoints of AN treatment include tumor control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL. It is uncertain if treating a small tumor leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment.   In this paper we review the literature for the natural course, the treatment alternatives and the results of AN. Finally, we present our experience with a management strategy applied for more than 30 years.

  6. Acoustic Spatiality

    Brandon LaBelle

    2012-06-01

    Full Text Available Experiences of listening can be appreciated as intensely relational, bringing us into contact with surrounding events, bodies and things. Given that sound propagates and expands outwardly, as a set of oscillations from a particular source, listening carries with it a sensual intensity, whereby auditory phenomena deliver intrusive and disruptive as well as soothing and assuring experiences. The physicality characteristic of sound suggests a deeply impressionistic, locational "knowledge structure" – that is, the ways in which listening affords processes of exchange, of being in the world, and from which we extend ourselves. Sound, as physical energy reflecting and absorbing into the materiality around us, and even one's self, provides a rich platform for understanding place and emplacement. Sound is always already a trace of location.Such features of auditory experience give suggestion for what I may call an acoustical paradigm – how sound sets in motion not only the material world but also the flows of the imagination, lending to forces of signification and social structure, and figuring us in relation to each other. The relationality of sound brings us into a steady web of interferences, each of which announces the promise or problematic of being somewhere.

  7. Springer Handbook of Acoustics

    Rossing, Thomas D

    2007-01-01

    Acoustics, the science of sound, has developed into a broad interdisciplinary field encompassing the academic disciplines of physics, engineering, psychology, speech, audiology, music, architecture, physiology, neuroscience, and others. The Springer Handbook of Acoustics is an unparalleled modern handbook reflecting this richly interdisciplinary nature edited by one of the acknowledged masters in the field, Thomas Rossing. Researchers and students benefit from the comprehensive contents spanning: animal acoustics including infrasound and ultrasound, environmental noise control, music and human speech and singing, physiological and psychological acoustics, architectural acoustics, physical and engineering acoustics, signal processing, medical acoustics, and ocean acoustics. This handbook reviews the most important areas of acoustics, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest rese...

  8. Responsive acoustic surfaces

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

    2011-01-01

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

  9. Measurements and Simulation Studies of Piezoceramics for Acoustic Particle Detection

    Salomon, K; Graf, K; Hoessl, J; Kappes, A; Karg, T; Katz, U; Lahmann, R; Naumann, C

    2005-01-01

    Calibration sources are an indispensable tool for all detectors. In acoustic particle detection the goal of a calibration source is to mimic neutrino signatures as expected from hadronic cascades. A simple and promising method for the emulation of neutrino signals are piezo ceramics. We will present results of measruements and simulations on these piezo ceramics.

  10. Practical quantum digital signature

    Yin, Hua-Lei; Fu, Yao; Chen, Zeng-Bing

    2016-03-01

    Guaranteeing nonrepudiation, unforgeability as well as transferability of a signature is one of the most vital safeguards in today's e-commerce era. Based on fundamental laws of quantum physics, quantum digital signature (QDS) aims to provide information-theoretic security for this cryptographic task. However, up to date, the previously proposed QDS protocols are impractical due to various challenging problems and most importantly, the requirement of authenticated (secure) quantum channels between participants. Here, we present the first quantum digital signature protocol that removes the assumption of authenticated quantum channels while remaining secure against the collective attacks. Besides, our QDS protocol can be practically implemented over more than 100 km under current mature technology as used in quantum key distribution.

  11. Investigating broadband acoustic adsorption using rapid manufacturing

    Godbold, O.

    The reduction of nuisance noise and the removal of unwanted sound modes within a room or component enclosure-area can be accomplished through the use of acoustic absorbers. Sound absorption can be achieved through conversion of the kinetic energy associated with pressure waves, into heat energy via viscous dissipation. This occurs within open porous materials, or by utilising resonant effects produced using simple cavity and orifice configurations. The manufacture of traditional porous and resonant absorbers is commonly realised using basic manufacturing techniques. These techniques restrict the geometry of a given resonant construction, and limit the configuration of porous absorbers. The aim of this work is to exploit new and emerging capabilities of Rapid Manufacturing (RM) to produce components with geometrical freedom, and apply it to the development of broadband acoustic absorption. New and novel absorber geometric configurations are identified and their absorption performance is determined. The capabilities and limitations of RM processes in reproducing these configurations are demonstrated. The geometric configuration of RM resonant absorbers is investigated. Cavity modifications aimed at damping the resonant effect by restricting the motion of cavity air, and adding increased viscous resistance are explored. Modifications relating to cavity shape, the addition of internal perforations and increased cavity surface area have all been shown to add acoustic resistance, thereby increasing the bandwidth of absorption. Decreasing the hydraulic radius of the cavity cross section and reducing internal feature dimensions provide improved resistance over conventional configurations..

  12. Acoustic source for generating an acoustic beam

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

    2016-05-31

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

  13. Acoustic vs VHF Lightning Location Systems

    Arechiga, R. O.; Lapierre, J. L.; Stock, M.; Erives, H.; Edens, H. E.; Stringer, A.; Rison, W.; Thomas, R. J.

    2013-12-01

    A single acoustic array can determine the 3-D location of lightning sources by using time of arrival differences arriving at the microphones and ranging techniques. The range is obtained from the time difference between the electromagnetic emission (detected by the acoustic data logger) and the acoustic signal produced by lightning. Audio frequency acoustic location systems are sensitive to the gas dynamic expansion of portions of a rapidly heating lightning channel, and so acoustic signatures are produced by a wide variety of different lightning discharge processes including: return strokes, K changes, M components, leader stepping and more. Infrasonic frequency range acoustic sensors are also sensitive to gas dynamic expansion, and in addition are also sensitive to processes which are electro-static in nature. RF location systems such as the Lightning Mapping Array (LMA) and the Continuous Sampling Broadband VHF Digital Interferometer (DITF) from New Mexico Tech (NMT) produce high quality maps of lightning discharges; however, they are sensitive to breakdown processes only and can not locate sources originating in already well conducting channels. During the summer of 2013 an acoustic audio-range array and an infrasound array were co-located with the NMT DITF in the Magdalena mountains of central New Mexico, where an LMA is also operating. The audio-range acoustic array consists of custom-designed GPS-synced data loggers with a 50 kHz sampling rate and audio range omnidirectional dynamic microphones. The infrasound array uses GPS time-synced data logger and custom-designed broadband microphones with flat response in the band of 0.01 to 500 Hz. The DITF uses flat plate dE/dt antennas bandpass filtered to 20 to 80 MHz, providing 2D maps of lightning emissions with very high (sub-microsecond) timing resolution. Both acoustic and interferometric arrays of antennas determine location of sources by coherently comparing the signals arriving at the antennas (or

  14. The Frequency Characteristics Simulation of Traveling Wave Thermo-Acoustic Engine

    Ma Lili

    2013-04-01

    Full Text Available The frequency characteristics of thermo-acoustic engine mainly depend on the internal working medium and device structure. The linear resonant system is consisted of ironless permanent magnet linear synchronous motor and the resonant spring. Through the analysis of thermo-acoustic power generation system model, the parameters of linear resonant system are determined by building a mathematical model of linear resonant system. Combined with modern control theory and robust control theory, a robust position controller was design. The theoretical analysis and simulation proved that the controller can make the linear resonance system obtain higher frequency response and displacement accuracy. Controller response time and output is more stable, the controller meets the necessary optimal control. The controller is suitable for thermal acoustic generator control system with high reliable and robust quantitative. The designed linear resonance system can well simulate the frequency characteristics of thermo-acoustic engine.

  15. Aperiodic logarithmic signatures

    Baumeister, Barbara

    2011-01-01

    In this paper we propose a method to construct logarithmic signatures which are not amalgamated transversal and further do not even have a periodic block. The latter property was crucial for the successful attack on the system MST3 by Blackburn et al. [1]. The idea for our construction is based on the theory in Szab\\'o's book about group factorizations [12].

  16. The dark energy signature

    Though the concept of a dark energy driven accelerating universe was introduced by the author in 1997, to date dark energy itself, as described below has remained a paradigm. We quickly review these and find a second cosmological signature of the 1997 model, consistent with latest observations. (author)

  17. UV missile plume signatures

    Neele, F.P.; Schleijpen, H.M.A.

    2002-01-01

    As a result of the deployment of UV missile warning systems, recent years have seen an increasing interest in threat assessment in the UV band. Unfortunately, due to the different nature of the physical processes that are needed to describe a missile signature in the UV, available codes for the IR c

  18. Acoustic force mapping in a hybrid acoustic-optical micromanipulation device supporting high resolution optical imaging.

    Thalhammer, Gregor; McDougall, Craig; MacDonald, Michael Peter; Ritsch-Marte, Monika

    2016-04-12

    Many applications in the life-sciences demand non-contact manipulation tools for forceful but nevertheless delicate handling of various types of sample. Moreover, the system should support high-resolution optical imaging. Here we present a hybrid acoustic/optical manipulation system which utilizes a transparent transducer, making it compatible with high-NA imaging in a microfluidic environment. The powerful acoustic trapping within a layered resonator, which is suitable for highly parallel particle handling, is complemented by the flexibility and selectivity of holographic optical tweezers, with the specimens being under high quality optical monitoring at all times. The dual acoustic/optical nature of the system lends itself to optically measure the exact acoustic force map, by means of direct force measurements on an optically trapped particle. For applications with (ultra-)high demand on the precision of the force measurements, the position of the objective used for the high-NA imaging may have significant influence on the acoustic force map in the probe chamber. We have characterized this influence experimentally and the findings were confirmed by model simulations. We show that it is possible to design the chamber and to choose the operating point in such a way as to avoid perturbations due to the objective lens. Moreover, we found that measuring the electrical impedance of the transducer provides an easy indicator for the acoustic resonances. PMID:27025398

  19. Atlantic Herring Acoustic Surveys

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Advanced Sampling Technologies Research Group conducts annual fisheries acoustic surveys using state-of-the-art acoustic, midwater trawling, and...

  20. Acoustic Neuroma Educational Video

    Full Text Available ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ...

  1. Acoustic Neuroma Educational Video

    Full Text Available ... is ANA? Mission Statement Board of Directors ANA Staff Medical Advisory Board News ANA Annual Reports Acoustic ... is ANA? Mission Statement Board of Directors ANA Staff Medical Advisory Board News ANA Annual Reports Acoustic ...

  2. Acoustic Neuroma Educational Video

    Full Text Available ... ANA Annual Reports Acoustic Neuroma Legacy Society Programs & Services Join/Renew Ways to Give ANA Discussion Forum ... ANA Annual Reports Acoustic Neuroma Legacy Society Programs & Services Search ANAUSA.org Connect with us! Educational Video ...

  3. Acoustic Neuroma Educational Video

    Full Text Available ... Resources Patient Surveys Related Links Clinical Trials.gov Health Care Insurance Toolkit Additional Resources ANA Public Webinars © 2016 Acoustic Neuroma Association Acoustic Neuroma Association ® • ...

  4. Acoustic Neuroma Educational Video

    Full Text Available ... Options Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask ... Options Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask ...

  5. Acoustic Neuroma Educational Video

    Full Text Available ... ANA Staff Medical Advisory Board News ANA Annual Reports Acoustic Neuroma Legacy Society Programs & Services Join/Renew ... ANA Staff Medical Advisory Board News ANA Annual Reports Acoustic Neuroma Legacy Society Programs & Services Search ANAUSA. ...

  6. Cystic acoustic neuromas

    Chitkara, Naveen; Chanda, Rakesh; Yadav, S. P. S.; N.K. Sharma

    2002-01-01

    Predominantly cystic acoustic neuromas are rare and they usually present with clinical and radiological features different from their more common solid counterparts. Two cases of cystic acoustic neuromas are reported here.

  7. Adaptive structural vibration control of acoustic deflector

    Ostasevicius, Vytautas; Palevicius, Arvydas; Ragulskis, Minvydas; Dagys, Donatas; Janusas, Giedrius

    2004-06-01

    Vehicle interior acoustics became an important design criterion. Both legal restrictions and the growing demand for comfort, force car manufacturers to optimize the vibro-acoustic behavior of their products. The main source of noise is, of course, the engine, but sometimes some ill-designed cover or other shell structure inside the car resonates and makes unpredicted noise. To avoid this, we must learn the genesis mechanism of such vibrations, having as subject complex 3D shells. The swift development of computer technologies opens the possibility to numerically predict and optimize the vibrations and noises.

  8. Ultrafast magnetoelastic probing of surface acoustic transients

    Janušonis, J.; Chang, C. L.; Jansma, T.; Gatilova, A.; Vlasov, V. S.; Lomonosov, A. M.; Temnov, V. V.; Tobey, R. I.

    2016-07-01

    We generate in-plane magnetoelastic waves in nickel films using the all-optical transient grating technique. When performed on amorphous glass substrates, two dominant magnetoelastic excitations can be resonantly driven by the underlying elastic distortions, the Rayleigh surface acoustic wave and the surface skimming longitudinal wave. An applied field, oriented in the sample plane, selectively tunes the coupling between magnetic precession and one of the elastic waves, thus demonstrating selective excitation of coexisting, large-amplitude magnetoelastic waves. Analytical calculations based on the Green's function approach corroborate the generation of multiple surface acoustic transients with disparate decay dynamics.

  9. NW-MILO Acoustic Data Collection

    Matzner, Shari; Myers, Joshua R.; Maxwell, Adam R.; Jones, Mark E.

    2010-02-17

    There is an enduring requirement to improve our ability to detect potential threats and discriminate these from the legitimate commercial and recreational activity ongoing in the nearshore/littoral portion of the maritime domain. The Northwest Maritime Information and Littoral Operations (NW-MILO) Program at PNNL’s Coastal Security Institute in Sequim, Washington is establishing a methodology to detect and classify these threats - in part through developing a better understanding of acoustic signatures in a near-shore environment. The purpose of the acoustic data collection described here is to investigate the acoustic signatures of small vessels. The data is being recorded continuously, 24 hours a day, along with radar track data and imagery. The recording began in August 2008, and to date the data contains tens of thousands of signals from small vessels recorded in a variety of environmental conditions. The quantity and variety of this data collection, with the supporting imagery and radar track data, makes it particularly useful for the development of robust acoustic signature models and advanced algorithms for signal classification and information extraction. The underwater acoustic sensing system is part of a multi-modal sensing system that is operating near the mouth of Sequim Bay. Sequim Bay opens onto the Straight of Juan de Fuca, which contains part of the border between the U.S. and Canada. Table 1 lists the specific components used for the NW-MILO system. The acoustic sensor is a hydrophone permanently deployed at a mean depth of about 3 meters. In addition to a hydrophone, the other sensors in the system are a marine radar, an electro-optical (EO) camera and an infra-red (IR) camera. The radar is integrated with a vessel tracking system (VTS) that provides position, speed and heading information. The data from all the sensors is recorded and saved to a central server. The data has been validated in terms of its usability for characterizing the

  10. Acoustic lens for capacitive micromachined ultrasonic transducers

    Capacitive micromachined ultrasonic transducers (CMUTs) have great potential to compete with traditional piezoelectric transducers in therapeutic ultrasound applications. In this paper we have designed, fabricated and developed an acoustic lens formed on the CMUT to mechanically focus ultrasound. The acoustic lens was designed based on the paraxial theory and made of silicone rubber for acoustic impedance matching and encapsulation. The CMUT was fabricated based on the local oxidation of silicon (LOCOS) and fusion-bonding. The fabricated CMUT was verified to behave like an electromechanical resonator in air and exhibited wideband response with a center frequency of 2.2 MHz in immersion. The fabrication for the acoustic lens contained two consecutive mold castings and directly formed on the surface of the CMUT. Applied with ac burst input voltages at the center frequency, the CMUT with the acoustic lens generated an output pressure of 1.89 MPa (peak-to-peak) at the focal point with an effective focal gain of 3.43 in immersion. Compared to the same CMUT without a lens, the CMUT with the acoustic lens demonstrated the ability to successfully focus ultrasound and provided a viable solution to the miniaturization of the multi-modality forward-looking endoscopes without electrical focusing. (paper)

  11. A PRACTICAL PROXY SIGNATURE SCHEME

    Sattar Aboud

    2012-01-01

    Full Text Available A proxy signature scheme is a variation of the ordinary digital signature scheme which enables a proxy signer to generate signatures on behalf of an original signer. In this paper, we present two efficient types of proxy signature scheme. The first one is the proxy signature for warrant partial delegation combines an advantage of two well known warrant partial delegation schemes. This proposed proxy signature scheme is based on the difficulty of solving the discrete logarithm problem. The second proposed scheme is based on threshold delegation the proxy signer power to sign the message is share. We claim that the proposed proxy signature schemes meet the security requirements and more practical than the existing proxy signature schemes.

  12. Two Improved Digital Signature Schemes

    2001-01-01

    In this paper, two improved digital signature schemes are presented based on the design of directed signaturescheme [3]. The peculiarity of the system is that only if the scheme is specific recipient, the signature is authenticated.Since the scheme adds the screen of some information parameters, the difficulty of deciphered keys and the security ofdigital signature system are increased.

  13. Strong signatures of right-handed compositeness

    Right-handed light quarks could be significantly composite, yet compatible with experimental searches at the LHC and precision tests on Standard Model couplings. In these scenarios, that are motivated by flavor physics, one expects large cross sections for the production of new resonances coupled to light quarks. We study experimental strong signatures of right-handed compositeness at the LHC, and constrain the parameter space of these models with recent results by ATLAS and CMS. We show that the LHC sensitivity could be significantly improved if dedicated searches were performed, in particular in multi-jet signals.

  14. Strong signatures of right-handed compositeness

    Redi, Michele [INFN, Sesto Fiorentino, Firenze (Italy); Sanz, Veronica [York Univ., Toronto, ON (Canada). Dept. of Physics and Astronomy; Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy; Vries, Maikel de; Weiler, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2013-05-15

    Right-handed light quarks could be significantly composite, yet compatible with experimental searches at the LHC and precision tests on Standard Model couplings. In these scenarios, that are motivated by flavor physics, one expects large cross sections for the production of new resonances coupled to light quarks. We study experimental strong signatures of right-handed compositeness at the LHC, and constrain the parameter space of these models with recent results by ATLAS and CMS. We show that the LHC sensitivity could be significantly improved if dedicated searches were performed, in particular in multi-jet signals.

  15. Acoustic metamaterial design and applications

    Zhang, Shu

    The explosion of interest in metamaterials is due to the dramatically increased manipulation ability over light as well as sound waves. This material research was stimulated by the opportunity to develop an artificial media with negative refractive index and the application in superlens which allows super-resolution imaging. High-resolution acoustic imaging techniques are the essential tools for nondestructive testing and medical screening. However, the spatial resolution of the conventional acoustic imaging methods is restricted by the incident wavelength of ultrasound. This is due to the quickly fading evanescent fields which carry the subwavelength features of objects. By focusing the propagating wave and recovering the evanescent field, a flat lens with negative-index can potentially overcome the diffraction limit. We present the first experimental demonstration of focusing ultrasound waves through a flat acoustic metamaterial lens composed of a planar network of subwavelength Helmholtz resonators. We observed a tight focus of half-wavelength in width at 60.5 KHz by imaging a point source. This result is in excellent agreement with the numerical simulation by transmission line model in which we derived the effective mass density and compressibility. This metamaterial lens also displays variable focal length at different frequencies. Our experiment shows the promise of designing compact and light-weight ultrasound imaging elements. Moreover, the concept of metamaterial extends far beyond negative refraction, rather giving enormous choice of material parameters for different applications. One of the most interesting examples these years is the invisible cloak. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. However, the cloak designed by transformation optics usually calls for a highly anisotropic metamaterial, which

  16. Resonances and resonance widths

    Two-dimensional betatron resonances are much more important than their simple one-dimensional counterparts and exhibit a strong dependence on the betatron phase advance per cell. A practical definition of ''width'' is expanded upon in order to display these relations in tables. A primarily pedagogical introduction is given to explain the tables, and also to encourage a wider capability for deriving resonance behavior and wider use of ''designer'' resonances

  17. ACOUSTICAL STANDARDS NEWS.

    Blaeser, Susan B; Struck, Christopher J

    2016-03-01

    American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, please contact Susan B. Blaeser.Comments are welcomed on all material in Acoustical Standards News.This Acoustical Standards News section in JASA, as well as the National Catalog of Acoustical Standards and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org. PMID:27036268

  18. Acoustical coupling of lizard eardrums.

    Christensen-Dalsgaard, Jakob; Manley, Geoffrey A

    2008-12-01

    Lizard ears are clear examples of two-input pressure-difference receivers, with up to 40-dB differences in eardrum vibration amplitude in response to ipsi- and contralateral stimulus directions. The directionality is created by acoustical coupling of the eardrums and interaction of the direct and indirect sound components on the eardrum. The ensuing pressure-difference characteristics generate the highest directionality of any similar-sized terrestrial vertebrate ear. The aim of the present study was to measure the gain of the direct and indirect sound components in three lizard species: Anolis sagrei and Basiliscus vittatus (iguanids) and Hemidactylus frenatus (gekkonid) by laser vibrometry, using either free-field sound or a headphone and coupler for stimulation. The directivity of the ear of these lizards is pronounced in the frequency range from 2 to 5 kHz. The directivity is ovoidal, asymmetrical across the midline, but largely symmetrical across the interaural axis (i.e., front-back). Occlusion of the contralateral ear abolishes the directionality. We stimulated the two eardrums with a coupler close to the eardrum to measure the gain of the sound pathways. Within the frequency range of maximal directionality, the interaural transmission gain (compared to sound arriving directly) is close to or even exceeds unity, indicating a pronounced acoustical transparency of the lizard head and resonances in the interaural cavities. Our results show that the directionality of the lizard ear is caused by the acoustic interaction of the two eardrums. The results can be largely explained by a simple acoustical model based on an electrical analog circuit. PMID:18648878

  19. Acoustics as a tool to enhance physics education

    Neilsen, Tracianne B.; Gee, Kent L.

    2016-03-01

    The use of acoustics in physics pedagogy, whether in stand-alone courses, or as examples, analogies, or demonstrations in other contexts, can enhance student learning. At most, a typical physics student receives only a few weeks of instruction in acoustics, despite its potential ability to enhance class discussions of source, resonance, and traveling-wave phenomena in both introductory and advanced settings. A recent annotated bibliography, includes specific resources for incorporating acoustics-based demonstrations into physics courses. Acoustics analogies can be used to illustrate wave phenomena in advanced contexts, such as diffraction, scattering, refraction, reflection, method of images, resonance, dispersion, tunneling. This presentation will review the Resource Letter, highlighting specific demonstration ideas, as well as offer additional perspectives gained since its publication.

  20. Spin wave acoustics of antiferromagnetic structures as magnetoacoustic metamaterials

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

    2011-06-30

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

  1. Spin wave acoustics of antiferromagnetic structures as magnetoacoustic metamaterials

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

  2. Signal Classification for Acoustic Neutrino Detection

    Neff, M; Enzenhöfer, A; Graf, K; Hößl, J; Katz, U; Lahmann, R; Richardt, C

    2011-01-01

    This article focuses on signal classification for deep-sea acoustic neutrino detection. In the deep sea, the background of transient signals is very diverse. Approaches like matched filtering are not sufficient to distinguish between neutrino-like signals and other transient signals with similar signature, which are forming the acoustic background for neutrino detection in the deep-sea environment. A classification system based on machine learning algorithms is analysed with the goal to find a robust and effective way to perform this task. For a well-trained model, a testing error on the level of one percent is achieved for strong classifiers like Random Forest and Boosting Trees using the extracted features of the signal as input and utilising dense clusters of sensors instead of single sensors.

  3. Simulating acoustic waves in spotted stars

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

    2015-01-01

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

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

    CHEN BAIMAN

    2011-06-01

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

  5. AST Launch Vehicle Acoustics

    Houston, Janice; Counter, D.; Giacomoni, D.

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.

  6. Decision Making in Acoustic Neuroma Management: The Only Hearing Ear

    Naguib, Maged B.; Saleh, Essam; Aristegui, Miguel; Mazzoni, Antonio; Sanna, Mario

    1994-01-01

    Patients with acoustic neuroma in their only hearing ear are not frequently seen in clinical practice. Managing this group of patients is a challenge to both patient and surgeon. In this study we report on five cases of acoustic neuroma in an only hearing ear. Our decision for nonsurgical management of those patients with regular follow-up using auditory brainstem responses and magnetic resonance imaging is discussed. Other management options currently available are considered as well.

  7. Optical transition radiation in presence of acoustic waves

    Mkrtchyan, A R; Saharian, A A

    2009-01-01

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

  8. Studies on acoustic modelling techniques for CANDU reactors

    This paper reviews the current technology being used to predict acoustic resonance in fluid-filled piping systems. The paper also reports on the analysis of a simple benchmark experiment that yielded some valuable insights and understanding into acoustic damping. A volumetric drag formula for the ABAQUS code is presented. Its application in experiments has yielded better results than previously obtained using a constant volumetric drag. (author). 24 refs., 1 tab., 12 figs

  9. Experimental Observation of Reversed Doppler Effects in Acoustic Metamaterials

    Zhai, Shilong; Zhao, Xiaopeng; Liu, Song; Luo, Chunrong

    2015-01-01

    This paper reports an experimental observation of broadband reversed Doppler effects using an acoustic metamaterial with seven flute-like double-meta-molecule clusters. Simulations and experiments verify that this locally resonant acoustic metamaterial with simultaneous negative elastic modulus and mass density can realize negative refraction in a broad frequency range. The constructed metamaterial exhibits broadband reversed Doppler effects. The frequency shift increases continuously as the ...

  10. Controller architectures for optimum performance in practical active acoustic metamaterials

    Reynolds, Matt; Daley, Steve; Gao, Yan; Humphrey, Victor; POPE, Simon

    2012-01-01

    Over the last decade there has been significant interest in the design and production of acoustic metamaterials with physical qualities not seen in naturally occurring media. Progress in this area has been stimulated by the desire to create materials that exhibit novel behaviour when subject to acoustic waves, such as negative refraction or the appearance of bandgaps in the frequency response of the material. Proposed designs range from locally resonant phononic crystals to arrays of Helmholt...

  11. A Novel Approach to Density Near-Zero Acoustic Metamaterials

    Milan Sečujski; Norbert Cselyuszka; Vesna Crnojević-Bengin

    2015-01-01

    The study demonstrates the possibility of achieving near-zero propagation of sound waves in acoustic metamaterials based on a membrane-based metamaterial unit cell which exhibits effective mass density of Lorentzian type. The unit cell, which represents the acoustic counterpart of the split ring resonator, was previously used as a building block of left-handed metamaterials, as it exhibits negative density at certain frequencies. In this study we show that its application can be extended to a...

  12. Controller architectures for optimum performance in practical active acoustic metamaterials

    Reynolds, Matthew; Daley, Steve; Gao, Yan; POPE, Simon

    2012-01-01

    Over the last decade there has been significant interest in the design and production of acoustic metamaterials with physical qualities not seen in naturally occurring media. Progress in this area has been stimulated by the desire to create materials that exhibit novel behaviour when subject to acoustic waves,such as negative refraction or the appearance of band gaps in the frequency response of the material. Proposed designs range from locally resonant phononic crystals to arrays of Helmholt...

  13. On Constructing Certificateless Proxy Signature from Certificateless Signature

    WAN Zhong-mei; LAI Xue-jia; WENG Jian; HONG Xuan; LONG Yu; JIA Wei-wei

    2008-01-01

    In proxy signature schemes,an original signer A delegates its signing capability to a proxy signer B,in such a way that B can sign message on behalf of A.The recipient of the final message verifies at the same time that B computes the signature and that A has delegated its signing capability to B.Recently many identity-based (ID-based) proxy signature schemes have been proposed,however,the problem of key escrow is inherent in this setting.Certificateless cryptography can overcome the key escrow problem.In this paper,we present a general security model for certificateless proxy signature scheme.Then,we give a method to construct a secure certificateless proxy scheme from a secure certificateless signature scheme,and prove that the security of the construction can be reduced to the security of the original certificateless signature scheme.

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

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

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

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

    2015-06-29

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

  16. The acoustic communities: Definition, description and ecological role.

    Farina, Almo; James, Philip

    2016-09-01

    An acoustic community is defined as an aggregation of species that produces sound by using internal or extra-body sound-producing tools. Such communities occur in aquatic (freshwater and marine) and terrestrial environments. An acoustic community is the biophonic component of a soundtope and is characterized by its acoustic signature, which results from the distribution of sonic information associated with signal amplitude and frequency. Distinct acoustic communities can be described according to habitat, the frequency range of the acoustic signals, and the time of day or the season. Near and far fields can be identified empirically, thus the acoustic community can be used as a proxy for biodiversity richness. The importance of ecoacoustic research is rapidly growing due to the increasing awareness of the intrusion of anthropogenic sounds (technophonies) into natural and human-modified ecosystems and the urgent need to adopt more efficient predictive tools to compensate for the effects of climate change. The concept of an acoustic community provides an operational scale for a non-intrusive biodiversity survey and analysis that can be carried out using new passive audio recording technology, coupled with methods of vast data processing and storage. PMID:27262416

  17. Artificial Seismic Shadow Zone by Acoustic Metamaterials

    Kim, Sang-Hoon; Das, Mukunda P.

    2012-01-01

    We developed a new method of earthquakeproof engineering to create an artificial seismic shadow zone using acoustic metamaterials. By designing huge empty boxes with a few side-holes corresponding to the resonance frequencies of seismic waves and burying them around the buildings that we want to protect, the velocity of the seismic wave becomes imaginary. The meta-barrier composed of many meta-boxes attenuates the seismic waves, which reduces the amplitude of the wave exponentially by dissipa...

  18. Signatures of nonthermal melting

    Tobias Zier

    2015-09-01

    Full Text Available Intense ultrashort laser pulses can melt crystals in less than a picosecond but, in spite of over thirty years of active research, for many materials it is not known to what extent thermal and nonthermal microscopic processes cause this ultrafast phenomenon. Here, we perform ab-initio molecular-dynamics simulations of silicon on a laser-excited potential-energy surface, exclusively revealing nonthermal signatures of laser-induced melting. From our simulated atomic trajectories, we compute the decay of five structure factors and the time-dependent structure function. We demonstrate how these quantities provide criteria to distinguish predominantly nonthermal from thermal melting.

  19. Resonance vector mode locking

    Kolpakov, Stanislav A; Loika, Yuri; Tarasov, Nikita; Kalashnikov, Vladimir; Agrawal, Govind P

    2015-01-01

    A mode locked fibre laser as a source of ultra-stable pulse train has revolutionised a wide range of fundamental and applied research areas by offering high peak powers, high repetition rates, femtosecond range pulse widths and a narrow linewidth. However, further progress in linewidth narrowing seems to be limited by the complexity of the carrier-envelope phase control. Here for the first time we demonstrate experimentally and theoretically a new mechanism of resonance vector self-mode locking where tuning in-cavity birefringence leads to excitation of the longitudinal modes sidebands accompanied by the resonance phase locking of sidebands with the adjacent longitudinal modes. An additional resonance with acoustic phonons provides the repetition rate tunability and linewidth narrowing down to Hz range that drastically reduces the complexity of the carrier-envelope phase control and so will open the way to advance lasers in the context of applications in metrology, spectroscopy, microwave photonics, astronomy...

  20. Superdimensional Metamaterial Resonators

    Greenleaf, Allan; Kurylev, Yaroslav; Lassas, Matti; Uhlmann, Gunther

    2014-01-01

    We propose a fundamentally new method for the design of metamaterial arrays, valid for any waves modeled by the Helmholtz equation, including scalar optics and acoustics. The design and analysis of these devices is based on eigenvalue and eigenfunction asymptotics of solutions to Schr\\"odinger wave equations with harmonic and degenerate potentials. These resonators behave superdimensionally, with a higher local density of eigenvalues and greater concentration of waves than expected from the physical dimension, e.g., planar resonators function as 3- or higher-dimensional media, and bulk material as effectively of dimension 4 or higher. Applications include antennas with a high density of resonant frequencies and giant focussing, and are potentially broadband.