Acoustic Control Research Articles

Dynamic Acoustic Holography: One-Shot High-Precision and High-Information Methodology

Acoustic holography technology is widely used in the field of ultrasound due to its capability to achieve complex acoustic fields. The traditional acoustic holography method based on single-phase holograms is limited due to its inability to complete acoustic field control with high dynamics and accuracy. Here, we propose a method for constructing an acoustic holographic model, introducing an ultrasonic array to provide dynamic amplitude control degrees of freedom, and combining the dynamically controllable ultrasonic array and high-precision acoustic hologram to achieve the highest acoustic field accuracy and dynamic range. This simulation method has been proven to be applicable to both simple linear patterns and complex surface patterns. Moreover, it is possible to reconstruct the degree of freedom of the target plane amplitude effectively and achieve a breakthrough in high information content. This high-efficiency acoustic field control capability has potential applications in ultrasound imaging, acoustic tweezers, and neuromodulation.

Selective collaboration in distributed FxLMS active noise control systems

This paper addresses the selection of the collaboration configuration on distributed active noise control (ANC) systems. ANC systems aim to cancel out acoustic noise within a listening area. In distributed systems, the control task is delegated among multiple acoustic control nodes that generate the control signals by filtering a noise reference signal. The coefficients of each node filter are iteratively calculated using the filtered-X LMS algorithm. The stability is achieved when the adaptive filters computed in each node converge to finite values. However, acoustic coupling among nodes could lead to instability (i.e., divergence). Collaboration among selected nodes may avoid this phenomenon, although not just any collaboration configuration guarantees network stability. On the other hand, a collaborative distributed system presents two drawbacks: the stability assessment is computationally expensive, and communication requirements increase with the number of collaborations among nodes. In this paper, we propose and discuss several methods to establish a collaboration configuration that ensures system stability. The optimal configuration, which is characterized by the minimal number of necessary collaborations between nodes, can be identified through exhaustive search. However, this approach incurs a high computational cost, particularly in networks with many nodes. To address this challenge, we introduce several heuristic methods aimed at efficiently obtaining stable configurations.

ESTRATÉGIAS DE CONFORTO AMBIENTAL PARA QUADRAS FECHADAS VOLTADAS A ESPORTES DE ALTO RENDIMENTO

Sports architecture, with its particularities, is essential to optimize the efficiency of environments, considering the specific needs of each sport. This article addresses environmental comfort strategies applied to indoor courts intended for high-performance sports, highlighting the importance of an architecturally planned environment to ensure the well-being of athletes and optimize their performance. The study focuses on thermal, visual, acoustic and ergonomic aspects, and analyzes how each of these factors influences sports performance. In addition, it explores the interaction between the body and the physical environment, proposing solutions that favor the creation of functional and comfortable spaces for sports practice and competitive events. The research, of a bibliographic and exploratory nature, brings together concepts of environmental psychology and athletic performance, in addition to highlighting the construction strategies of ventilation, lighting and acoustic control that can be applied to indoor courts with the aim of promoting human well-being. The work proposes solutions so that sports centers offer adequate conditions for sports practice, supporting the creation of environments that favor both the satisfaction and the enhancement of the performance of athletes. From this study, it is possible to define the importance of the preparation and competition environment in the performance of high-performance athletes, and architecture, linked to environmental comfort, is shown to be a tool for the development of these spaces, essential for success in national and international sports competitions.

Acoustography by Beam Engineering and Acoustic Control Node: BEACON.

Acoustic manipulation has emerged as a valuable tool for precision controls and dynamic programming of cells and particles. However, conventional acoustic manipulation approaches lack the finesse necessary to form intricate, configurable, continuous, and 3D patterning of particles. Here, this study reports acoustography by Beam Engineering and Acoustic Control Node (BEACON), which delivers intricate, configurable patterns by guiding particles along custom paths with independent phase modulation. Leveraging analytical methods of orbital angular momentum beam via iterative Wirtinger hologram algorithm, this study accomplish acoustography by facilitating orbital angular momentum traps, enabling continuous 2D and 3D acoustic manipulation of microparticles in any desired geometry, with phase modulation independent of intensity. Utilizing on-chip acoustography, the BEACON platform markedly increases the space-bandwidth product to 31000 while attaining an enhanced resolution with a pixel size of ≈25µm, surpassing the typical resolution of over 200µm in previous holographic particle manipulation methods. The capabilities of BEACON are demonstrated in creating intricate triple helical tracing structures using microdroplets (20µm in diameter) and those carrying DNA to validate the effectiveness of the acoustography and phase control methods. This study offers new particle manipulation opportunities, paving the way for next-generation biomedical systems and the future of contact-free precision manufacturing.

Experimental Evaluation of the Possibility of Through Defects Detection in Thermally Expanded Graphite Workpieces by Acoustic Method

The paper presents the results of evaluating the possibility of detecting defects (e.g., through holes) in workpieces made of thermally expanded graphite used as sealing materials using a non-contact air-coupled acoustic inspection system. The deviation of the acoustic signal amplitude when it passes through a sample of thermally expanded graphite in defective and defect-free regions is used as an informative parameter. The obtained dependences of the change in the amplitude of the passed signal through the sample on the size of the artificial through hole, density and thickness of the object showed a significant influence of these parameters on the detectability of the defect, which should be taken into account in the development of inspection technologies and in the process of its implementation. The change in the amplitude of the signal passed through the object directly depends on the increase in the parameters of the sample (density, thickness) and the size of the through hole, which increases the sensitivity of acoustic control and detectability of defects.On the basis of the obtained dependences the criteria for rejection of workpieces can be developed at the stage of production or immediately before manufacturing of their products. The influence of defect positioning relative to the acoustic axis of the transmitter-receiver system is shown, which leads to a decrease in the informative parameter, and consequently to a decrease in sensitivity. This dependence is characteristic for all thicknesses and densities of objects, as well as for all sizes of artificial through holes when control is carried out immediately after defect formation. When acoustic inspection is carried out some time after the defect formation, the maximum of this dependence may shift due to the shift of the amount of substance to fill the defect cavity, which is confirmed by microscopy. The obtained results can be used in the development of workpieces acoustic control parameters.

Analysis of dynamic levitation process of the particle chain in a nonlinear standing wave field.

This research delves into the dynamic behavior of acoustic levitation of the particle chain in a nonlinear standing wave field. Experimental acoustic levitation control tests reveal bifurcation and jump phenomena during dynamic adjustments to resonant cavity height. Employing the 10-particle chain experiments and the COMSOL simulation models, the Sine-Gordon 2D vibration model is established to study the dynamic deformation process of the particle chain. The study uncovers the nonlinear interaction of particle lateral vibrations, horizontal acoustic radiation force, and conical wave fields that generate the jumping standing wave field. Notably, the fourth particle acts as a prominent jumping critical point in the secondary standing wave field, facilitating the derivation of the particle chain's nonlinear levitation dynamics. This discovery provides us with a new method to regulate the particle chain system.

Multiband topological acoustic waveguide with multistage toroidal resonant cavities

In recent years, there has been significant development in acoustic waveguides through the introduction of topological phase correlation concepts in acoustics. Many studies have shown the properties of acoustic unidirectional transmission. This paper presents a new ring-shaped acoustic topological insulator that is multi-band, unlike previous structures. The structure improves internal space utilization with the same dimensions, reducing acoustic wave conduction frequency in air environments. Additionally, the introduction of a multistage ring-shaped resonant cavity enables the conduction of acoustic waves in multiple frequency bands. This paper employs the rotational scattering mechanism to invert the topological phase of the lattice. This allows for the construction of two crystals with opposite phases, which can be used to create a topological channel for the transmission of acoustic waves. At the topological interface, the acoustic transmission losses within the four bands are small. Furthermore, this paper verifies by simulation that the defects have little effect on acoustic transmission. The paper's research offers potential for multiband acoustic control.

A study on active structural acoustic control using force radiation modes

Active Structural Acoustic Control (ASAC) is an effective method for sound radiation control. To solve the coupling effect or inconvenience problems existed in the application of conventional methods, by utilizing the characteristic of intuitive representation of radiated sound power through force radiation modes, the control forces are designed to make the total excitation force vector orthogonal to each dominant force radiation mode. Therefore, an ASAC method by utilizing force radiation modes is proposed, and detailed theoretical research and numerical calculation analysis are carried out. The research results indicate that the control force requirement can be intuitively obtained through the force radiation modes, and decoupled control of radiated sound power corresponding to each force radiation mode is achieved by the proposed method. Thus, the control strategy and system construction can be greatly simplified, and structural acoustic radiation can be effectively controlled.

Aerodynamic and acoustic evaluation of a cylinder covered by stretched grooved fabric near critical Reynolds numbers

This study investigates aerodynamic drag and acoustic noise generated from a circular cylinder by wrapping longitudinally grooved fabrics. The fabrics are stretched to different levels to explore their potential for flow and acoustic control near critical Reynolds numbers. To analyze the fabrics' surface characteristics, 3D scanning and several microscopic techniques were employed. The parallel-mounted load cells and an array of microphones were used to measure the drag and noise at Reynolds numbers, based on cylinder diameter, ranging from \num{3.3e4} to \num{1.1e5} in an anechoic wind tunnel. Additionally, hotwire anemometry was used to examine the wake structures in the vicinity of the cylinder. The surface scanning results revealed that stretching the fabric transversely to twice its original size reduced the groove depth by approximately $54\%$ and increased the width by around $25\%$, resulting in an overall reduction of the arithmetic surface roughness $S_a$ by $18.6\%$. Based on the wind tunnel data, it was observed that a grooved fabric with higher stretch, and thus lower surface roughness exhibited a minimum drag coefficient at a higher Reynolds number, along with reduced acoustic tonal noise levels.

Inverse design of acoustic metamaterial-based vibration control for offshore wind turbines

This paper presents an inverse design approach for mechanical metamaterial turbines utilising a deep learning algorithm. We first establish a theoretical model for metamaterial turbines using the spectral element method to analyse their vibration characteristics. Subsequently, we predict the vibration transmission properties of these turbines and achieve on-demand inverse design of metastructures through a fully connected deep-learning neural network model. The efficacy of the forward prediction and reverse design network models is validated using an inverse neural network. Our results demonstrate a strong agreement between the predicted and target values, affirming the feasibility of employing deep learning for on-demand meta-turbine design. This intelligent design approach holds promise for expediting and enhancing the design of metamaterials tailored for low-frequency vibration isolation in engineering structures.

Acoustic insights into the corn extrusion process for enhanced quality control

In industrial extrusion processes, a solid material is pressed through a die to obtain products of the desired shape and dimension. Fluctuations in the process parameters have a significant impact on the product quality. In food extrusion, the expansion noise at the die can serve as an indicator of the stability of the process. This study employs microphones to characterize the corn extrusion process, focusing on correlating acoustic emissions with predefined process parameters such as feed intake and water content. Experimental data from laboratory and industrial settings reveal distinct domain shifts, yet consistent findings confirm the distinguishability of various extrusion process parameters by analyzing acoustic emissions. Employing machine learning models, including support vector machines and convolutional neural networks, in conjunction with audio features such as log Mel spectrograms, yields promising accuracies above 90\% in discriminating between standard and non-standard process parameters. The proposed acoustic quality control approach has the potential to enhance the stability of extrusion processes and contributes to the development of automated monitoring systems in the field of food extrusion. This ensures consistent quality and reduced waste, ultimately leading to significant cost savings in production.

Fear free design guidelines: exploration of quantitative acoustic criteria

Fear Free(r) is an organization that is dedicated to changing the landscape of veterinary medicine by educating veterinary professionals, architects, engineers, and others about the importance of considering the psychological impact of the built environment on animals. By involving an interdisciplinary team of veterinarians, architects, animal behaviorists, and others, the Fear Free Hospital Design Guideline has been developed to inform the design of animal care facilities. In partnering with Siebein Acoustic, new quantitative criteria can potentially be included as part of the Fear Free Design Guideline. The first step in reducing noise within any animal care environment is prevention, reducing or eliminating the stressors that cause dogs to bark. Metrics for measuring acoustic control include Reverberation Time, alpha bar, STC ratings, requiring a Site Noise Study if located in a sensitive area, the use of OITC ratings for the exterior building skin and mechanical criteria for the specific space types that are typical of animal care facilities. These criteria have been drafted to provide quantitative performance criteria to complement the design efforts that Fear Free is undertaking to transform animal care environments into healthy, vibrant spaces that promote the well-being and safety of all occupants, animals and humans alike.

Flexural behavior of innovative multifunctional concrete sandwich shells with different types of connectors

AbstractThis study develops an innovative multifunctional concrete sandwich shell based on a combined experimental and finite element (FE) study on its flexural behavior. The sandwich shell is made up of inner and outer concrete layers connected by connectors, with a middle functional layer that provides various functions such as insulation, acoustic, and vibration control. Bending tests were conducted on four groups of specimens, including three groups of sandwich shells with different types of connectors, that is, truss, grid, and plate connectors, and one reference group of solid shells. Loads, displacements, and strains were recorded during the tests. The FE analysis showed good correlation with the experimental results. Furthermore, a parametric study was conducted using the FE model to evaluate the influence of different parameters, such as middle layer thickness and number of connectors. The results show that the performance of the sandwich shell is comparable to, and in some cases better than, that of the solid shell, depending on the type of connectors used. This study provides a proof of concept for the sandwich shell and establishes a prototype structure for future research.

Transforming acoustic control: the first tunable broadband origami-based Helmholtz resonator

Abstract Helmholtz resonators have long been essential for acoustic control,
enhancing or nullifying sound at specific frequencies. Traditionally, these resonators are
effective for fixed-frequency applications, but lose efficacy if the excitation frequency
changes. This paper presents the first tunable broadband origami-based Helmholtz
resonator, featuring a compliant origami design with auxetic properties for optimal
volume variation. Multiphysics simulations determined the adaptive cavity geometry,
and experimental tests validated the models, showing high tunability (up to 25%
around a central frequency of 461 Hz with a 95% absorption rate) and broad bandwidth
(up to 13% around the central frequency with a 95% absorption rate) with minimal
geometry variation (8 mm in diameter). This work marks a significant advancement
over traditional Helmholtz resonators.

Unveiling Patient Perspectives: A Quality Assessment of User Satisfaction in a Leading Private Hospital in Gujranwala, Pakistan

Background: Inpatient departments are crucial for long-term patient care, requiring high-quality environmental conditions to ensure patient satisfaction. This study aimed to evaluate user satisfaction with the environmental quality of the male medical ward in Jinnah Memorial Hospital, Gujranwala, Pakistan.Objective: To assess the environmental quality and patient satisfaction within the male medical ward.Methods: A cross-sectional observational study was conducted from March to May 2019. Data were collected using a structured questionnaire administered to 100 respondents, including patients, staff, and attendants. Observations and environmental assessments were performed, focusing on thermal comfort, lighting, air quality, and ward design. Data analysis was conducted using SPSS version 25.Results: Only 28% of respondents were satisfied with thermal comfort, 40% with indoor air quality, 48% with acoustic control, and 30% with visual comfort. Issues highlighted included poor lighting, inadequate ventilation, and overcrowding, with 67% citing the hospital as expensive despite quality services.Conclusion: The study identified significant deficiencies in the environmental conditions of the male medical ward, necessitating targeted design interventions to improve patient satisfaction and overall healthcare quality.

Ultra-broadband illusion acoustics for space and time camouflages

Invisibility cloaks that can suppress wave scattering by objects have attracted a tremendous amount of interest in the past two decades. In comparison to prior methods that were severely limited by narrow bandwidths, here we present a practical strategy to suppress sound scattering across an ultra-broad spectrum by leveraging illusion metamaterials. Consisting of a collection of subwavelength tunnels with precisely crafted internal structures, this illusion metamaterial has the ability to guide acoustic waves around the obstacles and accurately recreate the incoming wavefront on the exit surface. Remarkably, two ultra-broadband illusionary effects are produced, disappearing space and time shift. Sound scatterings are removed at all frequencies below a limit determined by the tunnel width, as confirmed by full-wave simulations and acoustic experiments. Our strategy represents a universal approach to solve the key bottleneck of bandwidth limitation in the field of cloaking in transmission, and establishes a metamaterial platform that enables the long-desired ultra-broadband sound manipulation such as acoustic camouflage and reverberation control, opening up exciting new possibilities in practical applications.

Acoustically controlled bubble nucleation

Fundamental studies of single bubble heat transfer are crucial to improve our understanding of boiling phenomena and develop modeling and simulation tools for the design and optimization of boiling systems. However, conducting these kinds of experiments over a wide range of conditions is challenging and may involve expensive and complicated experimental techniques (e.g., lasers) to isolate and control bubble nucleation. In this work, we introduce a new technique to control nucleation with an ultrasonic beam. A low-cost and widely available piezoelectric disc driven at megahertz frequencies directed at a heated surface can increase the time-averaged pressure and suppress evaporation until the moment the transducer is turned off, allowing us to control the incipience of boiling to within 150 µs. We demonstrate this technique by measuring the physical and thermal footprint of natural and acoustically controlled bubbles with high-resolution infrared thermometry and phase detection diagnostics. We were able to raise the bubble nucleation temperature by over 30 K compared to a reference case with no acoustic control, which significantly changes bubble growth rate, microlayer formation and evaporation and departure diameter. We highlight the potential of this new low-cost and easy-to-use technique in a variety of different boiling heat transfer studies.

Methods of Manipulation of Acoustic Radiation Using Metamaterials with a Focus on Polymers: Design and Mechanism Insights.

The manipulation of acoustic waves is becoming increasingly crucial in research and practical applications. The coordinate transformation methods and acoustic metamaterials represent two significant areas of study that offer innovative strategies for precise acoustic wave control. This review highlights the applications of these methods in acoustic wave manipulation and examines their synergistic effects. We present the fundamental concepts of the coordinate transformation methods and their primary techniques for modulating electromagnetic and acoustic waves. Following this, we deeply study the principle of acoustic metamaterials, with particular emphasis on the superior acoustic properties of polymers. Moreover, the polymers have the characteristics of design flexibility and a light weight, which shows significant advantages in the preparation of acoustic metamaterials. The current research on the manipulation of various acoustic characteristics is reviewed. Furthermore, the paper discusses the combined use of the coordinate transformation methods and polymer acoustic metamaterials, emphasizing their complementary nature. Finally, this article envisions future research directions and challenges in acoustic wave manipulation, considering further technological progress and polymers' application potential. These efforts aim to unlock new possibilities and foster innovative ideas in the field.

Coherent Acoustic Control of Defect Orbital States in the Strong-Driving Limit

We use a bulk acoustic wave resonator to demonstrate coherent control of the excited orbital states in a diamond nitrogen-vacancy (NV) center at cryogenic temperature. Coherent quantum control is an essential tool for understanding and mitigating decoherence. Moreover, characterizing and controlling orbital states is a central challenge for quantum networking, where optical coherence is tied to orbital coherence. We study resonant multiphonon orbital Rabi oscillations in both the frequency and time domain, extracting the strength of the orbital-phonon interactions and the coherence of the acoustically driven orbital states. We reach the strong-driving limit, where the physics is dominated by the coupling induced by the acoustic waves. We find agreement between our measurements, quantum master-equation simulations, and a Landau-Zener transition model in the strong-driving limit. Using perturbation theory, we derive an expression for the orbital Rabi frequency versus the acoustic drive strength that is nonperturbative in the drive strength and agrees well with our measurements for all acoustic powers. Motivated by continuous-wave spin-resonance-based decoherence protection schemes, we model the orbital decoherence and find good agreement between our model and our measured few-to-several-nanoseconds orbital decoherence times. We discuss the outlook for orbital decoherence protection. Published by the American Physical Society 2024

Wind power prediction through acoustic data-driven online modeling and active wake control

Accurate online prediction of wind power is essential for the reliable operation of power systems. However, the precision of wind turbine power forecasts is often hindered by wake effects and inadequate online modeling capabilities. To tackle this issue, this paper proposes a data-driven online prediction method for wind turbine power, leveraging acoustic data for training. The approach involves a neural network that learns acoustic feature changes related to wind output power, by enhancing the kernel extreme learning machine (KELM) technique and applying data augmentation. Additionally, to address the wake effects in real wind fields, active wake control is integrated, considering that most wind turbines operate in the wake of upstream turbines. Experiments using actual wind tunnel measurement data were conducted to assess the performance of the proposed method. The findings demonstrate that this method surpasses other techniques without increasing computational costs. The mean absolute error (MAE) of the proposed method was only 0.4111 and 0.4302, and the root mean square error (RMSE) was just 0.4868 and 0.5195, respectively, in both experiments. Moreover, the proposed acoustic data-driven online power prediction method proves stable in high background noise environments and achieves accurate wind power prediction with just a 10% data sample following the implementation of the active wake control strategy. This work significantly contributes to the efficient utilization of wind energy resources.