Acoustic Wave Measurements Research Articles

Mach-Zehnder interferometry method for acoustic shock wave measurements in air and broadband calibration of microphones.

A Mach-Zehnder interferometer is used to measure spherically diverging N-waves in homogeneous air. An electrical spark source is used to generate high-amplitude (1800 Pa at 15 cm from the source) and short duration (50 μs) N-waves. Pressure waveforms are reconstructed from optical phase signals using an Abel-type inversion. It is shown that the interferometric method allows one to reach 0.4 μs of time resolution, which is 6 times better than the time resolution of a 1/8-in. condenser microphone (2.5 μs). Numerical modeling is used to validate the waveform reconstruction method. The waveform reconstruction method provides an error of less than 2% with respect to amplitude in the given experimental conditions. Optical measurement is used as a reference to calibrate a 1/8-in. condenser microphone. The frequency response function of the microphone is obtained by comparing the spectra of the waveforms resulting from optical and acoustical measurements. The optically measured pressure waveforms filtered with the microphone frequency response are in good agreement with the microphone output voltage. Therefore, an optical measurement method based on the Mach-Zehnder interferometer is a reliable tool to accurately characterize evolution of weak shock waves in air and to calibrate broadband acoustical microphones.

How to determine the relative ion concentrations of multiple-ion-species plasmas generated in the multi-dipole filament source

This paper introduces how to determine concentrations of ion species in a mixed gas plasma that are not linearly proportional to their neutral partial pressures. A particle balance model was developed to predict the relative ion concentrations in multiple-ion-species plasmas, considering their ionization rates and loss fluxes to the wall. Analysis is carried out especially with Ar/Xe and Ar/He multi-dipole plasmas in which the neutral gases are directly ionized by the mono-energetic primary electrons. The experimental data of ion concentrations were obtained using the ion acoustic wave measurement method of the concentration of two ion species. The comparison reveals that the ion concentration ratio is linearly proportional to the ratio of the ionization cross sections and the ion loss velocity between two gas species. Especially, the model prediction is improved with using the two-ion-species sheath model (recently reported by Baalrud and Hegna) for obtaining the ion loss velocity at the sheath boundary.

Functional and Histological Evaluation following Canine Vocal Fold Reconstruction Using Composite Thyroid Ala Perichondrium Flaps.

We evaluated the effects of vocal fold reconstruction using a composite thyroid ala perichondrium flap (CTAP) after unilateral vocal fold stripping in beagles. We hypothesized that CTAP would improve glottic closure, decrease phonation threshold pressure, and decrease perturbation. In addition, vocal folds with CTAP would exhibit neovascularization and fat with increased von Willebrand factor (vWF) and smooth muscle actin (SMA), reflecting neoangiogenesis and flap viability. Randomized controlled trial using beagles. University laboratory. Ten beagles underwent unilateral vocal fold stripping. Dogs in the scar-only group (n = 5) were sacrificed at 1 month. Dogs in the CTAP group (n = 5) underwent ipsilateral reconstruction with CTAP at 1 month and were sacrificed at 2 months. Excised larynx experiments evaluated vocal fold vibration using aerodynamic, acoustic, and mucosal wave measurements. Qualitative evaluation of vocal fold morphology and quantitative analysis of elastin, collagen, glycosaminoglycans, vWF, SMA, and hyaluronic acid were performed. Phonation threshold pressure (P = .005), percent jitter (P = .010), percent shimmer (P = .007), and open quotient (P = .007) were lower in the CTAP group. Neovascularization (P = .0079) and fat (P = .1667) occurred more with CTAP, although the difference in fat was not significant. von Willebrand factor was higher with CTAP vs contralateral normal fold (P = .110), although not statistically significant. Smooth muscle actin was higher with CTAP vs contralateral normal fold (P = .038) and scarred vocal folds (P = .022). Composite thyroid ala perichondrium flap restored glottic closure and vibratory periodicity following vocal fold scarring. Additional investigation on biologic response is warranted. Composite thyroid ala perichondrium flap offers an autologous, vascularized implant that can improve both vocal fold structure and function.

Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling

Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we measure lattice swelling and elastic modulus changes in a W-1% Re alloy after implantation with 3110appm of helium. An observed lattice expansion of a fraction of a per cent gives rise to an order of magnitude larger reduction in the surface acoustic wave velocity. A multiscale model, combining elasticity and density functional theory, is applied to the interpretation of observations. The measured lattice swelling is consistent with the relaxation volume of self-interstitial and helium-filled vacancy defects that dominate the helium-implanted material microstructure. Larger scale atomistic simulations using an empirical potential confirm the findings of the elasticity and density functional theory model for swelling. The reduction of surface acoustic wave velocity predicted by density functional theory calculations agrees remarkably well with experimental observations.

Functional and Histological Evaluation following Canine Vocal Fold Reconstruction Using Combined Thyroid Ala Perichondrium Flaps

Objectives: (1) Perform vocal fold reconstruction using composite thyroid ala perichondrium (CTAP) flaps in beagles following unilateral vocal fold stripping; (2) Evaluate aerodynamic, acoustic, vibratory, and histologic changes in canines undergoing CTAP-based vocal fold reconstruction compared to a control group undergoing injury alone. Methods: Unilateral vocal fold stripping was performed on ten beagles. Dogs healed for 1 month and were divided into 2 groups. Dogs in the control group (n = 5) were sacrificed. Dogs in the experimental group (n = 5) underwent ipsilateral vocal fold augmentation with a CTAP flap and recovered for 1 month prior to euthanasia. After euthanasia, larynges were harvested for excised larynx evaluation of vocal fold vibration using aerodynamic, acoustic, and mucosal wave measurements. Histological analysis was then performed on anterior, middle, and posterior sections of the vocal fold. Changes in the injured fold were compared between the control and experimental groups. Comparisons with the contralateral normal fold were made within the control and experimental groups. Results: Phonation threshold pressure was significantly lower in the treatment group ( P = .005). Percentage jitter ( P = .010) and shimmer ( P = .007) were also lower in the treatment group. Open quotient was significantly higher in the control group ( P = .007). Histological staining results were inconsistent, and gross analysis revealed evidence of surgical implantation without restoration of normal vocal fold architecture. Conclusions: CTAP-based vocal fold augmentation restored glottic closure and vibratory periodicity following vocal fold scarring. Additional investigation on biologic response is warranted. CTAP flaps offer an autologous, vascularized implant that can improve both vocal fold structure and function.

Elastic constants, Poisson ratios, and the elastic anisotropy of VN(001), (011), and (111) epitaxial layers grown by reactive magnetron sputter deposition

Elastic constants are determined for single-crystal stoichiometric NaCl-structure VN(001), VN(011), and VN(111) epitaxial layers grown by magnetically unbalanced reactive magnetron sputter deposition on 001-, 011-, and 111-oriented MgO substrates at 430 °C. The relaxed lattice parameter ao = 0.4134 ± 0.0004 nm, obtained from high-resolution reciprocal space maps, and the mass density ρ = 6.1 g/cm3, determined from the combination of Rutherford backscattering spectroscopy and film thickness measurements, of the VN layers are both in good agreement with reported values for bulk crystals. Sub-picosecond ultrasonic optical pump/probe techniques are used to generate and detect VN longitudinal sound waves with measured velocities v001 = 9.8 ± 0.3, v011 = 9.1 ± 0.3, and v111 = 9.1 ± 0.3 km/s. The VN c11 elastic constant is determined from the sound wave velocity measurements as 585 ± 30 GPa; the c44 elastic constant, 126 ± 3 GPa, is obtained from surface acoustic wave measurements. From the combination of c11, c44, vhkl, and ρ we obtain the VN c12 elastic constant 178 ± 33 GPa, the VN elastic anisotropy A = 0.62, the isotropic Poisson ratio ν = 0.29, and the anisotropic Poisson ratios ν001 = 0.23, ν011 = 0.30, and ν111 = 0.29.

Elastic Softening of Surface Acoustic Wave Caused by Vacancy Orbital in Silicon Wafer

We have performed surface acoustic wave (SAW) measurements to examine vacancies in a surface layer of a boron-doped silicon wafer currently used in semiconductor industry. A SAW with a frequency of fs = 517 MHz was optimally generated by an interdigital transducer with a comb gap of \(w=2.5\) µm on a piezoelectric ZnO film deposited on the (001) silicon surface. The SAW propagating along the [100] axis with a velocity of \(v_{\text{s}}=4.967\) km/s is in agreement with the Rayleigh wave, which shows an ellipsoidal trajectory motion in the displacement components ux and uz within a penetration depth of λp = 3.5 µm. The elastic constant Cs of the SAW revealed the softening of ΔCs/Cs = 1.9 × 10−4 below 2 K down to 23 mK. Applied magnetic fields of up to 2 T completely suppress the softening. The quadrupole susceptibilities based on the coupling between the electric quadrupoles Ou, Ov, and Ozx of the vacancy orbital consisting of Γ8–Γ7 states and the symmetry strains eu, ev, and ezx associated with the SAW ac...

Deficit Irrigation of Miniature Tomato Based on Estimation of Embolism Risk by Measurements of Acoustic Emission and Stress Wave at Stem

Deficit Irrigation of Miniature Tomato Based on Estimation of Embolism Risk by Measurements of Acoustic Emission and Stress Wave at Stem

Surface acoustic wave in temperature compensated NdCa 4 O(BO 3 ) 3 crystal

A two-port synchronous resonator was used for measurements of surface acoustic wave (SAW) parameters in the Y-plane of NdCa4O(BO3)3 crystal. For YX–5°, YX and YX + 5° orientations, the SAW phase velocity under free surface, electromechanical coupling coefficient, second-order temperature coefficient of frequency and turnover temperature (T O) of about 3481, 3502 and 3503 m/s; 0.68, 0.63 and 0.6%; −37, −32 and −70 ppb/°C2 and 80, 25 and −35 °C, respectively, were obtained. The crystal was assessed as attractive in SAW applications due to temperature compensation and high electromechanical coupling coefficient.

Fabrication of broadband poly(vinylidene difluoride-trifluroethylene) line-focus ultrasonic transducers for surface acoustic wave measurements of anisotropy of a (1 0 0) silicon wafer

This paper investigates a new method for fabrication of broadband line-focus ultrasonic transducers by sol–gel spin-coating the poly(vinylidene difluoride-trifluroethylene) [P(VDF-TrFE)] copolymer film on a concave fine-polished beryllium copper backing. The ferroelectric hysteresis loops of the P(VDF-TrFE) films spin-coated from different molar ratios of VDF/TrFE, 77/23 and 55/45, were measured to select the better mixture. Owing to the better acoustic matching to water, compared with lead zirconate titanate (PZT), the fabricated transducers show relatively wide bandwidth of approximately 50MHz with high central frequency of 60MHz obtained at the focal plane when a fused-quartz acts as a reflecting target. Each one of the two finished transducers has a focal length of 5mm and a full aperture angle of 90°. After applying the specially developed digital signal processing algorithm to the defocusing experiment data, which is called V(f,z) analysis method based on two-dimensional fast Fourier transform (2-D FFT), the operating frequency can extend from several MHz to over 90MHz. Surface acoustic wave (SAW) velocities of a typical (100) silicon wafer was measured along various directions between [100] and [010] to represent the anisotropic features.

Volumetric measurements of a spatially growing dust acoustic wave

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

Accuracy Evaluation of Surface Temperature Profiling by a Laser Ultrasonic Method

Accuracy in measuring surface temperature distributions by a laser ultrasonic method is examined. Surface temperature distributions of an aluminum plate whose single side is heated up to 110 °C are estimated by the inverse analysis coupled with surface acoustic wave (SAW) measurements, and the results are compared with those measured by an infrared radiation method. A random fluctuation in the temperature estimated by the ultrasonic method is observed and decreases with an increase in the distance from the heating area. The standard deviation in fluctuation is estimated to be about 2 °C at the heating area. Furthermore, the systematic errors in the temperature estimation due to the deviations in the temperature dependence of SAW velocity and thermal diffusivity are investigated. It is found that the temperature dependence of SAW is an important factor affecting the systematic error, but the influence of the deviation in thermal diffusivity is negligible.

Depth Evaluation of Fretting Fatigue Crack Appearing at Bolt Joints of Aluminum Alloy Plates by Synchronized Surface Acoustic Wave Measurement

The surface acoustic wave (SAW) measurement was carried out for the bolted specimen of aluminum alloy by synchronizing the ultrasonic pulsation with a fatigue cycle in the fatigue testing. The reflection from the crack increased in the loading stage of the fatigue cycle, reached maximum and then decreased in the unloading stage of the fatigue cycle. The sigmoidal intensity change of the reflection from the fatigue crack in a fatigue cycle occurred following opening/closing behavior of the crack, and the intensity took the maximum value when the crack was fully opened. The SAW intensity distribution between the crack and the bolt hole edge was also analyzed to evaluate the depth of the crack: the SAW intensity distribution after the crack root was subjected to the band-pass filtering to recognize the creeping wave (the longitudinal wave) reflected from the crack tip, and then the crack depth was estimated from the propagation time of the creeping wave from the crack root to the crack tip, which was in good agreement with the value measured in the cross section of the specimen and evaluated through the scanning acoustic analysis.

The flexural properties of young Pinus elliottii x Pinus caribaea var. hondurensis timber from the Southern Cape and their prediction from acoustic measurements

The objectives of this study were to determine the bending strength and stiffness properties of young Pinus elliottii x P. caribaea var. hondurensis timber from the Southern Cape, South Africa, and to evaluate the predictability of these properties from acoustic measurements on standing trees, logs and their sawn boards. The timber has good bending strength (MOR) properties but the mean stiffness (MOEstat) was significantly lower than that required for structural-grade timber. The mean MOEstat was also about 30% lower than a P. radiata control sample. The MOEstat of sawn boards could be predicted from acoustic stress wave measurements on standing trees with a correlation (r) of 0.48 and from acoustic resonance frequency measurements on sawn boards with a correlation of 0.85. The MOR of sawn boards was not significantly correlated with acoustic stress wave measurements on standing trees and only moderately correlated with acoustic resonance frequency measurements on sawn boards (r = 0.45).

Beam distortion detection and deflectometry measurements of gigahertz surface acoustic waves

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

Noncontact Monitoring of Surface Temperature Distribution by Laser Ultrasound Scanning

A laser ultrasound scanning method for measuring a surface temperature distribution of a heated material is presented. An experiment using an aluminum plate heated up to 120 °C is carried out to verify the feasibility of the proposed method. A series of one-dimensional surface acoustic wave (SAW) measurements within an area of a square on the aluminum surface are performed by scanning a pulsed laser for generating SAW using a galvanometer system, where the SAWs are detected at a fixed location on the surface. An inverse analysis is then applied to SAW data to determine the surface temperature distribution in a certain direction. The two-dimensional distribution of the surface temperature in the square is constructed by combining the one-dimensional surface temperature distributions obtained within the square. The surface temperature distributions obtained by the proposed method almost agrees with those obtained using an infrared radiation camera.

Optimal arytenoid adduction based on quantitative real‐time voice analysis

The optimal degree of arytenoid rotation for arytenoid adduction (AA) can be determined using quantitative real-time voice analysis. Repeated measures with each larynx serving as its own control. Unilateral vocal fold paralysis (VFP) was modeled in five excised canine larynges. Medialization laryngoplasty (ML) was performed, followed by AA. The optimal degree of arytenoid rotation was determined using real-time measurements of vocal efficiency (V(E) ), percent jitter, and percent shimmer. After the optimal degree of rotation was determined, the arytenoid was hypo- and hyperrotated 10% ± 2% of the optimal angle to mimic hypoadducted and hyperadducted states. Aerodynamic, acoustic, and mucosal wave measurements were recorded. Mean optimal angle of arytenoid adduction was 151.4 ± 2.5°. V(E) differed significantly across experimental conditions (P = .003). Optimal AA produced the highest V(E) of any treatment, but this value did not reach that produced in the normal condition. Percent jitter (P < .001) and percent shimmer (P < .001) differed across groups and were lowest for optimal AA. Mucosal wave amplitude of the normal (P = .001) and paralyzed fold (P = .043) differed across treatments. Amplitude of both folds was highest for optimal AA. V(E) and perturbation parameters were sensitive to the degree of arytenoid rotation. Using real-time voice analysis may aid surgeons in determining the optimal degree of arytenoid rotation when performing AA. Testing this method in patients and determining if optimal vocal outcomes are associated with optimal respiratory and swallowing outcomes will be essential to establishing clinical viability.

Reconstruction of the Refraction Index in Stratified Ocean

The paper deals with an inverse problem arising in harmonic acoustics in ocean, where the concern is the reconstruction of the acoustic refraction index. A set of uniqueness for the reconstruction of the index is provided. It is also shown that one measurement of acoustic waves at the surface and bottom is enough to reconstruct the acoustic refraction index if it is known close to the surface.

Piezoelectric Multimaterial Fibers

ABSTRACTHere we report on the design, fabrication, and characterization of fiber containing an internal crystalline non-centrosymmetric phase enabling piezoelectric functionality over extended fiber lengths [1]. A ferroelectric polymer layer of 30 μm thickness is spatially confined and electrically contacted by internal viscous electrodes and encapsulated in an insulating polymer cladding hundreds of microns in diameter. The structure is thermally drawn in its entirety from a macroscopic preform, yielding tens of meters of piezoelectric fiber. Electric fields in excess of 50V/μm are applied through the internal electrodes to the ferroelectric layer leading to effective poling of the structure. To unequivocally establish that the internal copolymer layer is macroscopically poled we adopt a two-step approach. First, we show that the internal piezoelectric modulation indeed translates to a motion of the fiber’s surface using a heterodyne optical vibrometer at kHz frequencies. Second, we proceed to an acoustic wave measurement at MHz frequencies: a water-immersion ultrasonic transducer is coupled to a fiber sample across a water tank, and frequency-domain characterizations are carried out using the fiber successively as an acoustic sensor and actuator. These measurements establish the broadband piezoelectric response and acoustic transduction capability of the fiber. The potential to modulate sophisticated optical devices is illustrated by constructing a single-fiber electricallydriven device containing a high-quality-factor Fabry-Perot optical resonator and a piezoelectric transducer.

THE SEISMOACOUSTIC WAVEFIELD: A NEW PARADIGM IN STUDYING GEOPHYSICAL PHENOMENA

[1] The field of seismoacoustics is emerging as an important discipline in its own right, owing to the value of colocated seismic and infrasound arrays that sample elastic energy propagating in both the solid Earth and the atmosphere. The fusion of seismic and infrasonic data provides unique constraints for studying a broad range of topics including the source physics of natural and man-made events, interaction of mechanical waves in Earth's crust and atmosphere, source location and characterization, and inversion of atmospheric and shallow subsurface properties. This review article traces the seismoacoustic wavefield from source to receiver. Beginning at the source, we review the latest insights into the physics of natural and anthropogenic sources that have arisen from the analysis of seismoacoustic data. Next, a comparative review of 3-D models of the atmosphere and solid Earth and the latest algorithms for modeling the propagation of mechanical waves through these media provides the framework for a discussion of the seismoacoustic path. The optimal measurement of seismic and acoustic waves, including a discussion of instrumentation, as well as of array configurations and regional networks, is then outlined. Finally, we focus on broad research applications where the analysis of seismoacoustic data is starting to yield important new results, such as in the field of nuclear explosion monitoring. This review is intended to provide a primer on the field of seismoacoustics for seismologists or acousticians, while also providing a more general review of what constraints seismoacoustics can uniquely provide for understanding geophysical phenomena.