Interference Of Acoustic Waves Research Articles

Experimental research on the horizontally getting together behaviors of acoustically manipulated bi-particle

This study aims at the controllability of acoustically manipulated non-contact aggregation of bi-particle. Based on the acoustic wave radiation model of the transducer and the acoustic wave interference theory, the mathematical model between the spatial levitation point and the phase of the phased array ultrasonic array unit is established. A double-sided phased array test system was developed and the phase calculation algorithm for independently manipulating bi-particle was optimized. The algorithm is capable of independently distributing the energy applied to each levitation point. Through simulation and experiment, the horizontally aggregation characteristics of two levitated particles are investigated, and a interesting relationship between particles aggregation and standing wave phase difference is revealed, which follows the law of “attraction in the same phase but repulsion in the opposite phase”. By adjusting the tilt angle of the standing wave acoustic trap, the critical distance when particles to accelerate and collision is sharply reduced from 1.5λ to 0.5λ, which provides a new perspective and potential application path for acoustic manipulation technology.

Thermally driven hybrid metastructure for multi-functional surface acoustic wave engineering

Acoustic wave engineering through solid mediums are essential for improving or optimizing the performances of various platforms, such as biomedical and industrial applications. Metamaterials or metasurfaces have been recently developed to artificially manipulate the wave propagation passing through mediums. However, they only conduct one fixed function passively, determined by the structure design for the particular wavelength, and their fabrication involves high-cost and complex procedures. Here, we report a thermally driven hybrid metastructure (HMS) for actively controlling surface acoustic waves. The HMS is designed as the layered structure of a thermoresponsive polymer (TP), thermal metamaterials (TMs) and an intermediate layer (IL) made of silica aerogel. For providing multi-functions, TPs conduct the considerable elastic modulus changes and corresponding wave manipulation at a certain glass transition temperature while TMs enable the programmed heating configuration, and the IL mitigates thermal and acoustic wave interference. By introducing the IL, the entire energy of the propagating wave is captured at the interface and interference between the wave and thermal energy is prevented, which directly reflects the temperature control through the TMs into the TP heating configuration. Versatile functions of programmable wave engineering including omnidirectional wave focusing-collimation through modified Luneberg lenses, dual-functioning focusing-bifurcation, and double refraction through 3-phase wave steering are demonstrated using the proposed HMS implemented by the temperature gradient design of TMs. This work will inspire tunable and scalable platforms for active controls of wave propagation enabled by thermal energy as a driving force.

Anisotropy of the Near‐Field Coseismic Ionospheric Perturbation Amplitudes Reflecting the Source Process: The 2023 February Turkey Earthquakes

AbstractThe East Anatolian Fault in southern Turkey ruptured on 6 February 2023, causing a Mw 7.8 earthquake (EQ1), one of the largest strike‐slip events recorded on land. ∼9 hr later, earthquake of Mw 7.7 (EQ2) occurred to the north of EQ1. We investigate here near‐field coseismic ionospheric perturbations (CIP) caused by acoustic waves (AWs) excited by coseismic vertical crustal movements. We find that observed CIP periods were somewhat longer for EQ1 than EQ2. EQ1 also showed azimuthal dependence in CIP amplitudes that cannot be explained by known factors such as geomagnetism and line‐of‐sight geometry. Numerical experiments revealed that CIP by EQ1 can be well reproduced by assuming a suite of sources along the fault that successively ruptured. Small but significant dependence of amplitudes and periods on azimuths were caused by interference of AWs from multiple sources. We also found that CIP amplitudes of strike‐slip earthquakes tend to be lower than dip‐slip earthquakes.

On-Chip RF Signal Shaping by Coherent Control of Optically Driven Acoustic Wave Interference

Photonic–phononic systems that mix photons and acoustic waves have been actively investigated for the development of next-generation integrated photonics for signal processing. Here, we propose a new method of arbitrary RF signal shaping using active control of optically driven acoustic-wave interference, offering new photonic–phononic–microwave signal processing schemes with MHz linewidths at GHz carrier frequencies. The demonstrated system consists of two suspended optical waveguides and an asymmetric Mach–Zehnder interferometer. The two waveguides generate acoustic waves at a 3.03 GHz carrier frequency with a 3.3 MHz bandwidth, and one of the paths of the asymmetric interferometer experiences phase modulation induced by the acoustic waves. Then, the interferometer converts the phase information to RF signals of complicated shapes using a linear combination of multiple optical envelopes. This RF signal-shaping method will open new applications of optomechanical systems for microwave photonics.

Binary amplitude switch for photoacoustic transducer toward dynamic spatial acoustic field modulation.

Photoacoustic (PA) transducers are an attractive method of producing high-amplitude, high-frequency, broad-bandwidth ultrasound signals with excellent immunity to electromagnetic interference, when compared with their traditional electroacoustic counterparts. However, the lack of effective control over the spatial sound field prohibits PA transducer technology from further widespread application. This paper presents the first, to the best of our knowledge, experimental study on the dynamic spatial ultrasound modulation strategy for the use of PA transducers, in which a novel PA transducer element is designed. This consists of a suspended compound PA conversion film, whose backing condition can be switched between air and glass through pneumatic actuation to create destructive and constructive acoustic wave interference, respectively. As a result, nearly an order of magnitude contrast in the output acoustic amplitude can be obtained by switching the device's backing condition given the same laser excitation, thus achieving a binary amplitude tuning. Furthermore, a linear PA transducer array consisting of three independently controllable elements is used for a proof-of-concept demonstration of the dynamic spatial sound field manipulation. To the best of the authors' knowledge, this is the first time that such a unique capability has been successfully applied to PA transducer technology.

Real-time prediction framework for frequency-modulated multirotor noise

A comprehensive multirotor noise assessment framework is developed to predict the noise of rotational-speed-controlled rotor configurations in real-time. The key objectives are to synthesize the frequency-modulated multirotor noise and analyze the frequency modulation (FM) characteristics. The framework includes modules associated with the flight control, aerodynamics, time reconstruction, noise prediction, and time-frequency analysis (TFA). In addition to the hybrid blade element momentum model, the aerodynamics module contains a linear inflow model, a Beddoes wake model, and an unsteady aerodynamic correction model. The convective form and source-time dominant algorithms are used in the acoustic analogy for tonal noise prediction. The FM characteristics are identified using the synchrosqueezing-based high-resolution TFA for strongly non-stationary signals. The framework is verified through validation and verification studies for diverse rotor configurations and flight conditions. During the cruise flight of the multirotor, the tonal noise exhibits simultaneous frequency and amplitude modulations. In wind gust conditions, these modulations result from rotational speed variations, acoustic wave interference, and Doppler shifting. By clarifying the non-stationary noise signal in diverse flight environments, the proposed framework can facilitate noise assessment in the perception-influenced design stage of multirotor configurations.

The Behavior of Microdroplets By the Acoustic Wave Interference

The microdroplet in the air have been recently issued in the view of environmental pollution and infectious virus. The microdroplet with fine dust have been challenged to solve with conventional techniques such as filtering, electrostatic, etc. We investigated the novel technology for decreasing the fine particles in air induced by sound wave with the frequency ranging from 20Hz to 20kHz and the sound pressure level (SPL) from 0 to 100dB.The test systems in our study were set up with constraint box, sound wave actuator, ultra-fine particle distributor, particle counter, decibel meter, etc. the variation of density of ultra-fine particles from distributor was characterized with operating time of sound wave, and compared with the density as no operating.When the low frequency and the SPL under 50Hz and 100dB were applied in the constraint box containing ultra-fine particles, the rate of decrease of ultra-fine particles in density was nearly 5 times higher than that without operating. And it can be applied to increase the efficiency of the conventional particle collection technology such as the commercial filter.It is concluded that the behavior of microdroplets was effectively analyzed by the acoustic wave interference, and also is expected to be applied to the various fields

Optical coherent control of stimulated Brillouin scattering via acoustic wave interference.

We propose and demonstrate a novel method for controlling stimulated Brillouin scattering with light in a phase-sensitive manner. Our results indicate that Brillouin gain can be enhanced or suppressed in a polarization-maintaining fiber via acoustic wave interference by controlling the relative phase of orthogonally polarized light, which induces acoustic waves. This method paves the way for the all-optical control of Brillouin interaction.

Noise control of a two-stage screw refrigeration compressor

Twin-screw compressors are widely used in refrigeration systems, but typically suffer from severe vibration and noise due to pulsing gas flow during operation. Gas pulsation is the main noise excitation source of screw compressors, presenting significant fundamental harmonic characteristics. This study examined noise control technologies for screw refrigeration compressor designs, such as acoustic wave interference, gas–solid resonance, and perforated muffler. Based on the structure characteristics and noise spectrum characteristics of a single-machine two-stage screw refrigeration compressor, several noise reduction measures were tested, including a half-wavelength tube, Helmholtz resonator, and multi-cavity series muffler. The experimental results show that after optimization, the noise measured on the exhaust side was reduced from 85.3 dB(A) to 81.9 dB(A) under the rated conditions of −25 °C evaporating temperature and 50 °C condensing temperature. At a constant 50 °C condensation temperature, the noise on the exhaust side of the compressor decreased from 93.7 dB(A) to 85.9 dB(A), an improvement of 7.8 dB(A), at 0 °C evaporation temperature. At an evaporation temperature of 5 °C, the noise on the exhaust side of the compressor decreased from 95.6 dB(A) to 86.5 dB(A), an improvement of 9.1 dB(A), indicating effective optimization under variable working conditions.

Development of Self-Focusing Piezoelectric Composite Ultrasound Transducer Using Laser Engraving Technology.

Based on the Fresnel half-wave band interference and laser engraving, a high-frequency self-focusing piezoelectric composite ultrasound transducer (FPCUT) is presented in this article. The theoretical analysis was performed based on the concept of constructive interference of acoustic waves and the electromechanical response of piezoelectric composites. The calculated and simulation results showed that the FPCUT combined the advantages of the composite transducer and the plate self-focusing transducer and can achieve high electromechanical coupling coefficient (>0.66), low acoustic impedance (~15 MRayl), high intensity, and short focal length. Furthermore, a 30-MHz self-focusing piezoelectric composite transducer prototype was fabricated and tested. It is composed of 11 lead zirconate titanates (PZTs) and ten epoxy annuluses. A UV engraving laser with a linewidth of 10 [Formula: see text] was used in each of the PZTs to form the annuluses, and the kerf among the annuluses was filled with epoxy. The measured center frequency, bandwidth, and focal length were 27 MHz, 50.37%, and 3.7 mm, respectively. A vertical wire phantom was imaged using a fabricated transducer and a contrast flat transducer; the images showed significant improvement in the lateral resolution over a range of 9 mm. Because this self-focusing piezoelectric composite transducer was based on the precise laser engraving systems, the fabrication process was accurate and controllable, which enabled it to have good potential for medical imaging and industrial nondestructive testing applications.

An Improved Phased Array Ultrasonic Testing Technique for Thick-Wall Polyethylene Pipe Used in Nuclear Power Plant

With the application of high-density polyethylene (HDPE) pipe with thick wall in nuclear power plant (NPP), great attention has been paid to the safety of the pipeline joints, which can be assessed by phased array ultrasonic testing (PAUT). PAUT creates constructive interference of acoustic waves to generate focused beams according to delay law based on time-of-flight. However, due to the existence of acoustic attenuation and dispersion, waveform distortion occurs when ultrasonic pulse propagates in HDPE, which will accumulate with the increase of propagation distance, and then results in imaging errors. In this paper, the relationship between acoustic attenuation and dispersion in HDPE was obtained by numerical simulation in Field II®, which can be verified by the experiment of our previous work. Then, the investigation of the waveform distortion revealed the linear relation between peak offset and propagation distance. Considering the relation, an improved delay law was proposed to increase the intensity of ultrasonic field. This improved delay law was compared with the conventional one by numerical simulation of ultrasonic field and PAUT experiments, which showed that the improved delay law could increase the image sensitivity.

Targeted sound attenuation capacity of 3D printed noise cancelling waveguides

The study explores the creation of 3D printed sound cancelling waveguides that can be customised for selected frequencies as a function of geometry. The potential for attenuation in these waveguides is characterised through experimentally measured acoustic-absorption (α) and Transmission Loss (TL). This was done to evaluate the potential of geometry-controlled waveguides in the development of passive sound cancelling structures. Geometrically complex waveguides to exploit the Herschel–Quincke-Arjunan (HQA) waveguide model manufactured in Nylon-12 using Selective Laser Melting (SLM) are presented. The attenuation of the waveguides was compared to the bulk Nylon-12 materials to segregate the material-based influence. The results showed that the performance of HQA waveguides can be controlled as a function of length, diameter and waveguide-tortuosity. Accordingly, under right parameters significant improvement in α (0.96, 0.80, 0.61 and 0.98) and TL (65.59%, 30.15%, 53.36% and 95.28%) can be achieved at the design frequency. The proposed methodology can be used to develop customisable waveguides exploiting the principles of acoustic wave interference for a range of application including building walls, noise barriers and absorptive panels.

Coherent coupling between radio frequency, optical, and acoustic waves in piezo-optomechanical circuits.

Optomechanical cavities have been studied for applications ranging from sensing to quantum information science. Here, we develop a platform for nanoscale cavity optomechanical circuits in which optomechanical cavities supporting co-localized 1550 nm photons and 2.4 GHz phonons are combined with photonic and phononic waveguides. Working in GaAs facilitates manipulation of the localized mechanical mode either with a radio frequency (RF) field through the piezo-electric effect, which produces acoustic waves that are routed and coupled to the optomechanical cavity by phononic crystal waveguides, or optically through the strong photoelastic effect. Along with mechanical state preparation and sensitive readout, we use this to demonstrate an acoustic wave interference effect, similar to atomic coherent population trapping, in which RF-driven coherent mechanical motion is cancelled by optically-driven motion. Manipulating cavity optomechanical systems with equal facility through both photonic and phononic channels enables new architectures for signal transduction between the optical, electrical, and mechanical domains.

Prediction of tunneling hazardous geological zones using the active seismic approach

ABSTRACTThis paper presents a seismic method and a newly developed device to predict the hazardous geological zones ahead of a tunnel face. The equipment used to predict hazardous geological zones consists of three components: the seismic source, the acquisition unit, and the data processing unit. The following features enable this device to be a valuable tool in predicting hazardous geological zones: the precise trigger time detection; the application of semi‐liquid couplant, which improves geophone coupling with the surrounding rock; the filtering of the prominent tunnel acoustic wave interference; and a software package of information on hazardous geological zones. Through extensive detection exercises of hazardous geological zones in the excavations of nearly 100 tunnel projects in China, it has been demonstrated that this device can satisfactorily predict hazardous geological zones, such as faults, water‐bearing zones, karst caverns, etc., within 150 m in front of the tunnel faces.

Pututus, resonance and beats: Acoustic wave interference effects at Ancient Chavín de Huántar, Perú

Acoustic wave interference produces audible effects observed and measured in archaeoacoustic research at the 3,000-year-old Andean Formative site at Chavín de Huántar, Perú. The ceremonial center’s highly-coupled network of labyrinthine interior spaces is riddled with resonances excited by the lower-frequency range of site-excavated conch shell horns. These pututus, when played together in near-unison tones, produce a distinct “beat” effect heard as the result of the amplitude variation that characterizes this linear interaction. Despite the straightforward acoustic explanation for this architecturally enhanced instrumental sound effect, the performative act reveals an intriguing perceptual complication. While playing pututus inside Chavín’s substantially intact stone-and-earthen-mortar buildings, pututu performers have reported an experience of having their instruments’ tones “guided” or “pulled” into tune with the dominant spatial resonances of particular locations. In an ancient ritual context, the recognition and understanding of such a sensory component would relate to a particular worldview beyond the reach of present-day investigators. Despite our temporal distance, an examination of the intertwined acoustic phenomena operative to this architectural–instrumental–experiential puzzle enriches the interdisciplinary research perspective, and substantiates perceptual claims.

Design of micromachined self-focusing piezoelectric composite ultrasound transducer.

Based on the Fresnel half-wave band interference, a micromachined self-focusing piezoelectric composite ultrasound transducer was proposed in this paper. The theoretical analysis was deduced based on the concept of constructive interference of acoustic waves and electromechanical response of piezoelectric composites. The calculated and simulation results showed that it combined the advantages of composite transducer and plate self-focusing transducer, and can achieve high electromechanical coupling coefficient, low acoustic impedance, high intensity, short focal length and micro size. Because it was based on the micro-electromechanical systems, the fabrication process was accurate and controllable, which made it have good potential for interventional ultrasound imaging, cellular microstructure imaging, skin cancer detection and industrial nondestructive testing applications.

Valveless micropump driven by acoustic streaming

This paper describes two valveless micropumps built on a 260 µm thick PZT with 20 µm thick parylene acoustic Fresnel lenses with air cavities. The micropumps produce in-plane body force through acoustic streaming effect of high-intensity acoustic beam that is generated by acoustic wave interference. The fabricated micropumps were shown to move microspheres, which have a diameter of 70–90 µm and a density of 0.99 g cm−3, on the water surface to form U-shape streams of microspheres with a drift velocity of 7.3 cm s−1 when the micropumps were located 4 mm below the water surface and driven by 160 Vpeak-to-peak pulsed sinusoidal waves. The driven microspheres formed U-shape streaming even without any fluidic channel according to the serial connection of the pie-shaped lenses and top electrodes. A micropump with a straight-lined fluidic channel was also fabricated and tested to show a 9.2 cm s−1 microspheres' drift velocity and a 9.5 mL min−1 volume pumping rate when combined with the acrylic acoustic wave reflector. Both the Fresnel lens and top electrode were patterned in a pie-shape with its apex angle of 90° to form asymmetric acoustic pressure distribution at the focal plane of the acoustic Fresnel lenses in order to push water in one direction.

Screenless unidirectional hydroacoustic transducers with electrically controlled radiation interference in the rear direction

The results of calculations of frequency characteristics are presented that were obtained from solution of the synthesis and analysis problems for broadband unidirectional rod transducers with controlled interference of acoustic waves in the rear direction provided by the phase excitation of two parts of a piezo rod. The influences of the methods of excitation and different construction parameters on the frequency characteristics are analyzed. Experimental data are presented.

Spatial Variability Caused by Acoustic Wave Interference in Single-Drive Direct Field Acoustic Testing

A significant amount of acoustic spatial variability is characteristic of direct field acoustic testing using a single random signal to drive the loudspeaker sources. This has raised concerns about the potential for under- and over-testing of hardware, particularly because of the consequential high sensitivity of the test environment upon the configuration of the test equipment and test hardware. Meanwhile, little is known about the specific spatial characteristics of the test acoustic field. A recent demonstration single-drive direct field acoustic test afforded the opportunity to map various planes of the acoustic field with a 36 microphone grid, offering unprecedented physical insight into the field characteristics. Analysis of the data reveals that the field is predominantly characterized by wave interference patterns at any given frequency. These data correlate well with 3-dimensional numerical models. The presence of wave interference patterns created by the fully correlated array of sources also explains the occurrence of frequency bands where the acoustic levels were significantly overdriven as a consequence of the control microphone locations coinciding with acoustic nodes associated with the corresponding drive frequencies. For comparison, the same mapping was performed in a conventional reverberant chamber test with the microphone grid, showing detailed contrast in spatial characteristics between the two test methods. This paper presents the highlights of this study and discusses ramifications for the use of this methodology.

115 3次元空間用ANCシステムの開発(騒音・振動の能動制御(3))

Passive noise control such as sound absorption and sound insulation is commonly used as noise reduction measures. It is effective against high-frequency noise, but not effective against low-frequency noise. As appropriate measures for the low-frequency noise, there is active noise control (ANC) system. The system generates a sound whose amplitude is same as noise and phase is opposite to noise. The sound causes the acoustic wave interference and erases the noise. It is used well in one dimension space like the duct, but there are few examples of practical use in three dimension space. Then, we developed the ANC system that can be applied to three dimension space.