Resonance Noise Research Articles

Research on the application of second-order HR in attenuating tire cavity resonance noise

Tire cavity resonance noise (TCRN) is well-known as one of the significant sources causing the interior noise at low-frequency band. Previous research shows that Helmholtz resonator (HR) array in an automotive wheel may obviously attenuate TCRN. To further improve the effect, the second-order HRs in the HR array are introduced here. Firstly, the theoretical model of second-order HR is established, and the results are verified by finite element method. The results show that the second-order HR with the same cavity volume may produce two transmission loss peaks, and a higher peak than that of the original first-order HR in the specified frequency band. Then, the optimization is performed to obtain a higher effect of attenuating TCRN at the original design frequency and a certain effect of attenuating road noise in the specified lower-frequency band. The results indicate that the desired effect may be achieved, and the higher resonance frequency can easily fall in the frequency band below 600Hz although hard to fall in the frequency band of TCRN. So the second-order HR is helpful to improve attenuating road noise including TCRN.

Acoustic optimization of a tee via a Helmholtz resonant cavity and noise prediction via a genetic algorithm coupled with the grey model

As a key local component in heating, ventilation and air conditioning (HVAC) systems, the acoustic characteristics of the tee largely determine the indoor acoustic environment quality. The aim of this study was to determine the impact of the Helmholtz resonant cavity (HRC) on the tee noise and sound transmission loss (STL). The noise was predicted using the Ffowcs Williams-Hawkings (FW-H) equation and large eddy simulation (LES), and an analysis was conducted on four design variables: the cavity width, cavity height, outlet flow ratio, and hole width. The results indicated that increasing the hole width had a positive effect on reducing the noise of the tee. HRC could result in a tee peak noise attenuation up to 34.81 dB. In addition, based on grey model (GM) and genetic algorithm (GA) theory, the noise of the Helmholtz resonant tee (HRT) was predicted, and a noise prediction formula for resonant cavity structure paraments was derived. This study provides a new perspective for optimizing the STL of the tee and a simplified prediction method for low-noise tee design.

Resonant noise amplification in a predator-prey model with quasi-discrete generations

Predator-prey models have been shown to exhibit resonance-like behaviour, in which random fluctuations in the number of organisms (demographic noise) are amplified when their frequency is close to the natural oscillatory frequency of the system. This behaviour has been traditionally studied in models with exponentially distributed replication and death times. Here we consider a biologically more realistic model, in which organisms replicate quasi-synchronously such that the distribution of replication times has a narrow maximum at some T>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$T>0$$\\end{document} corresponding to the mean doubling time. We show that when the frequency of replication f=1/T\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f=1/T$$\\end{document} is tuned to the natural oscillatory frequency of the predator-prey model, the system exhibits oscillations that are much stronger than in the model with Poissonian (non-synchronous) replication and death. These oscillations lead to population instability and the extinction of one of the species much sooner than in the case of Poissonian replication. The effect can be explained by resonant amplification of coloured noise generated by quasi-synchronous replication events.

A Power-Efficient Envelope-Detector-Less Amplitude-Shift-Keying Forward Telemetry for Wirelessly Powered Biomedical Devices.

This paper proposes an envelope-detector-less (EDL) amplitude-shift-keying (ASK) forward telemetry (FT) demodulator for wireless power/data transfer (WPDT) systems. The EDL ASK FT demodulator can substitute bulky and power-hungry components, which are an envelope detector and an analog comparator in the conventional ASK FT demodulator, with a digital controller, reducing both power dissipation and chip area. The proposed demodulator shares the gate control signals of pass transistors, which are used in an ac-dc regulator for wireless power reception, to maintain a constant load voltage while efficiently demodulating the forward telemetry data. Also, a proposed digital cleaner in the EDL demodulator refines this control signal into a wide pulse without suffering from resonant frequency noise, while a synchronizer can align its frequency with the data rate and resonant frequency. The 0.25-μm CMOS prototype chip of the proposed power-path-less EDL ASK FT demodulator, equipped with the ac-dc regulator, demonstrates a significant 38.2% reduction in power dissipation compared to the conventional ASK FT demodulator. Moreover, the EDL ASK FT demodulator occupies only 0.023-mm2 silicon area and achieves a low bit error rate (BER) less than 10-4 while maintaining a regulated voltage of 4.5 V on the load.

Multi-objective topology optimization simulation study based on motor

Abstract OptiStruct software is applied for structural optimization of the motor structure to solve the problem of resonance in a specific operating frequency range and reduce the motor operating noise. Comparing the experimental and simulated modal frequencies, a modified multi-objective topology optimization model is proposed to ensure the validity of the model, and a new optimization function is constructed to optimize the multi-objective topology of the motor housing. The results show that the geometric reconfiguration of the motor housing concerning the optimized model force transmission path achieves the effectiveness of reducing resonance noise. The multi-objective topology optimization model provides a feasible way to solve the motor-specific frequency resonance and operation noise problems.

Stochastic resonance noise modified decision solution for binary hypothesis-testing under minimax criterion

In this paper, on the premise that the prior probability is unknown, a noise enhanced binary hypothesis-testing is investigated under the Minimax criterion for a general nonlinear system. Firstly, for lowering the decision risk, an additive noise is intentionally injected to the input and a decision is made under Minimax criterion based on the noise modified output. Then an optimization problem for minimizing the maximum of Bayesian conditional risk under an equality constraint is formulated via analyzing the relationship between the additive noise and the optimal noise modified Minimax decision rule. Furthermore, lemma and theorem are proposed to prove that the optimal noise is a constant vector, which simplifies the optimization problem greatly. An algorithm is also developed to search the optimal constant and the key parameter of detector, and further to determine the decision rule and the Bayes risk. Finally, simulation results about the original (in the absence of additive noise) and the noise-modified optimal decision solutions under Minimax criterion for a sine transform system are provided to illustrate the theoretical results.

Suppression effect of the leading-edge groove on deep cavity noise at low speeds: Groove length

Detached Eddy Simulations combined with Ffowcs Williams–Hawkings acoustic analogy of subsonic flows over a deep cavity preceded by deep grooves with different lengths were conducted to investigate the effects of groove length on the flow characteristics and the noise suppression in the vicinity of the deep cavity. The length-to-depth ratio of the deep cavity is 2/3, and the length-to-depth ratios of the grooves are 1/2. The distance between the grooves and the cavity remains constant at twice the groove length. The groove length ranges from 5 mm to 30 mm. The Reynolds number based on the cavity length is 8 × 10−5. The analysis results indicate that all grooves studied in this paper have some effect on the distribution of sound energy of near-field noise and near-/far-field noise amplitude, but have no effect on the characteristic frequencies of cavity noise and far-field noise directivity. When the groove length is 15 mm and 20 mm, the deep grooves are most effective in suppressing deep cavity noise. The time-averaged velocities in the incoming boundary layer, shear layer, and wake region decrease, and the height of the boundary layer downstream of the cavity increases, which reduces the intensity of the interaction between the flow structure and solid wall downstream of the cavity, resulting in a reduction in flow-acoustic feedback noise. Meanwhile, the suppression effect of the groove flow on the cavity flow effectively alters the flow characteristics of the entire cavity mouth, the rear edge wall, and part of the bottom surface region, reducing the energy at these locations. This is the primary reason for the reduction in broadband noise and acoustic resonance noise.

Accelerated time history iteration method for offline real‐time hybrid testing

AbstractReal‐time hybrid testing (RTHT) is an efficient method to simulate the dynamic behavior of complex engineering systems. A novel offline RTHT method has been developed in recent years, wherein the computation of the numerical substructure and the loading of the experimental substructure are independent. Offline RTHT has obvious advantages in terms of accuracy, stability, and cost compared with conventional online RTHT. However, due to the excessive number of iterations, the application range of the existing offline RTHT methods is limited. This paper proposes an accelerated time history iteration (ATHI) method based on system identification and virtual iteration. A two‐loop parameter optimization (TLPO) method is developed to obtain an accurate discrete transfer function. Virtual iterations are performed by replacing the real system with an identified transfer function, which can reduce the number of real iterations. Physical tests were performed on structures equipped with a tuned mass damper or active mass damper, where resonance, nonlinearity, closed‐loop control, and measurement noise exist. The test results suggest that the real system can be accurately represented by the identified transfer function when adopting the TLPO method. The proposed ATHI successfully accelerates the convergence process while ensuring stability and accuracy.

Joint magnetic resonance imaging artifacts and noise reduction on discrete shape space of images

Magnetic resonance (MR) images can be corrupted by artifacts and noise, potentially leading to misinterpretation of the images. In this paper, we propose a novel approach based on the discrete shape space of images (DSSI) to jointly reduce artifacts and noise in MR images. The proposed method restores MR images in multiple domains based on the distinct generation mechanisms of noise and artifacts. The images in multiple domains are analyzed in a non-Euclidean space. The DSSI is constructed as a Riemannian manifold to measure the intrinsic properties of images. Images are considered shapes from a geometric perspective, and the impact of similarity transformations (e.g., rotation, scaling, and translation) on image analysis is eliminated. The patch-based rank-ordered difference (PROD) detector is defined in k-space within the framework of DSSI to detect and remove sparse outliers that cause artifacts. In addition, a novel similarity function for images is defined using the DSSI and be used to design the improved filter. Finally, the convergence of the improved filter is theoretically analyzed, indicating that our method offers an effective estimator of the ideal image. The experimental results of various MR images demonstrate that the proposed approach outperforms classical and state-of-the-art methods for artifact correction and noise removal, both qualitatively and quantitatively.

Research on noise reduction methods for indoor substations based on resonant sound absorption

Aiming to reduce the impact of substation noise on the lives of surrounding residents, improving the low and middle frequencies acoustic performance of traditional resistive mufflers in indoor substations is significant. The paper is based on the resonance sound absorption mechanism, and for the first time applies multi-frequency resonance noise reduction technology to the research field of indoor substation noise control, proposing a multi-frequency resonant muffling structure. The acoustic performance of the proposed muffler unit is investigated through theoretical and numerical analysis. The measured noise data of the indoor substation is used as sound excitation in the numerical analysis. The results show that at frequencies of 100 Hz, 200 Hz, 300 Hz, 400 Hz, and 500 Hz, the noise in indoor substations is significantly reduced by the multi-frequency resonant muffling structure. The paper provides references for the application of multi-frequency resonant mufflers in the field of noise control of indoor substations.

Phase noise matching in resonant metasurfaces forintrinsic sensing stability.

Interferometry offers a precise means of interrogating resonances in dielectric and plasmonic metasurfaces, surpassing spectrometer-imposed resolution limits. However, interferometry implementations often face complexity or instability issues due to heightened sensitivity. Here, we address the necessity for noise compensation and tolerance by harnessing the inherent capabilities of photonic resonances. Our proposed solution, termed "resonant phase noise matching," employs optical referencing to align the phases of equally sensitive, orthogonal components of the same mode. This effectively mitigates drift and noise, facilitating the detection of subtle phase changes induced by a target analyte through spatially selective surface functionalization. Validation of this strategy using Fano resonances in a 2D photonic crystal slab showcases noteworthy phase stability (). With demonstrated label-free detection of low-molecular-weight proteins at clinically relevant concentrations, resonant phase noise matching presents itself as a potentially valuable strategy for advancing scalable, high-performance sensing technology beyond traditional laboratory settings.

Volumetric rigid MR-CT registration for glioblastoma in radiation oncology: A Novel approach

Glioblastoma multiforme (GBM), is a highly aggressive and rapidly growing grade IV astrocytoma that originates from astrocytes and causes a diverse range of neurological problems by infiltratingsurrounding brain tissue. Image guided radiotherapy is a crucial treatment option for GBM; however, precise target delineation is critical for efficient treatment in the presence of noise and distortion in the magnetic resonance (MR) and computed tomography (CT) images. Multimodal image registration, which generates aligned or fused images from different modalities, can enhance target delineation accuracy. The objective of this study was to evaluate the effectiveness of volumetric multimodal MR-CT rigid registration algorithms for the patients with GBM and to enhance the success of radiotherapy treatment responses by employing visual inspection and statistical assessment of the registered images. Specialized algorithms were developed to attain volumetric registration, leading to an enhanced target delineation for radiation treatment. The crucial role of multimodal rigid registration in improving the accuracy of target delineation in the context of radiation oncology for GBM was underscored by this study.

Research on acoustic-structural coupling model and tire parameters of tire acoustic cavity resonance noise

Tire acoustic cavity resonance (TACR) noise is one kind of low-frequency and narrowband noise that particularly annoys passengers, especially becomes more prominent in electric vehicles. This paper demonstrates a numerical investigation on the TACR noise via the acoustic-structural coupling finite element model. The accuracy of this coupling finite element model is validated both by the analytic method based on the superposition theory of traveling waves and experimental modal tests of tire cavities. According to the simulated models, the influences of external factors including the inflation pressure and road load on the TACR noise are studied. Meanwhile, as the main constituent component in the tire model, the effect of belt cord is also discussed. To design the low-TACR noise tire, various design parameters of the inner contour in tire cavity are analyzed. By the orthogonal test and range analysis, it is found that the contour parameters can slightly affect the modal frequency and sound pressure of TACR noise. Among these, the curvature radius of the tire shoulder ρ 4, tire sidewall ρ 5, and half-section height H have a more obvious influence on the TACR noise than the curvature radius of the tire crown region ρ 2 and transition region ρ 3. Meanwhile, it also illustrates that increasing the curvature radius at the tire shoulder ρ 4 and reducing the half-section height H has a reduction effect on the TACR noise. This study can contribute to the design of low road noise tires.

The Rapid Identification and Evaluation of the Resonant Noise of a Cooling Module Based on the Frequency Difference Sensitivity Method

The energy amplification factor transmitted from the excitation source to the response end cannot be identified quickly and accurately using the method of obtaining modal frequency combined with damping through modal frequency resonance. As a result, the above method cannot be used to further evaluate the effect of structural improvement. In this paper, a frequency difference sensitivity method is proposed in order to improve the efficiency of the above identification and evaluation processes while also guaranteeing accuracy. Firstly, a theoretical model suitable for the damping and rigid-body-mode frequency range of the cooling module is established according to the frequency difference between the excitation frequency, .system mode frequency, and vibration response sensitivity. Then, the accuracy and effect of the model are studied from the perspective of a simulation and experiment. The model can be used to identify and evaluate the resonance problem of the vehicle cooling module quickly and accurately. The energy amplification factor of the fan to the passive end of the cooling module can be efficiently predicted using the frequency difference sensitivity method proposed in this paper while ensuring accuracy. The quantized noise-reduction effect of the interior before and after the improvement can be efficiently predicted and evaluated using said model. The literature shows that the resonance of a vehicle cooling module can be identified and evaluated quickly and accurately via the frequency difference sensitivity method, which can overcome the problems that the conventional modal frequency resonance method encounters in identifying and evaluating quickly.

Numerical investigation of tire shape parameters on the tire acoustic cavity resonance noise

Tire acoustic cavity resonance (TACR) noise is one kind of low-frequency and narrowband noise that particularly annoys the passengers, especially beyond endurance in the electric vehicles. This paper demonstrates a numerical investigation on the TACR noise via the acoustic-structural coupling finite element model. According to the simulated models, shape parameters of inner tire cavity have been studied in detail, including the curvature radius of tire crown region ρ2, transition region ρ3, tire shoulder ρ4, and tire sidewall ρ5, together with the half-section height H of the inner tire cavity. By the orthogonal test and range analysis, it is found that the curvature radius of the tire shoulder ρ4, tire sidewall ρ5, and half-section height H have a more obvious influence on the TACR noise, rather than the curvature radius of tire crown region ρ2 and transition region ρ3. Meanwhile, it also illustrates that increasing the curvature radius at the tire shoulder ρ4 and reducing the half-section height H have a reduction effect on the TACR noise. This study can contribute to the design of low road noise tire.

Experimental study of applying plant-derived materials to sound-absorbing structures for cabin noise reduction of electric vehicles

Electric vehicles generate different interior noise than internal combustion engine vehicles at low speeds. To investigate the cause of the interior noise of electric vehicles at low speeds (30 km/h) and to reduce the noise, a Helmholtz resonator made of molded pulp, a material derived from plants, is fabricated, and its noise reduction effect is experimentally evaluated. First, a molded pulp Helmholtz resonator is fabricated and tested with an impedance tube. Then, this Helmholtz resonator is installed inside the tire and can reduce the cavity resonance noise. Then, driving tests are conducted on an electric vehicle with tires equipped with this molded pulp, and it is possible to reduce the sound pressure at the ear position at the frequency of the tire cavity resonance. Finally, driving tests are conducted with standard tires, and this molded pulp in the cabin reduces the noise at the tire cavity resonance frequency. From this, at low speeds (30 km/h), we can demonstrate that tire cavity resonance is the source of noise in an electric vehicle's cabin and that it is possible to reduce tire cavity resonance without directly installing Helmholtz resonator in the tires.

Research on Propagation Characteristics of Tire Cavity Resonance Noise in the Automobile Suspension

Tire cavity resonance noise (TCRN) is one of main contributors to vehicle interior noise, which has long been a concern in the automotive industry and academia. As suspension is crucial for the propagation of TCRN energy into the vehicle, the propagation characteristics of energy in automobile suspension is studied in this research. Firstly, the finite element model of a McPherson suspension system connected to an aluminum alloy wheel with a Y-shaped spoke was established. Then, a modal analysis and response calculations of the McPherson suspension system connected to the aluminum alloy wheel with a Y-shaped spoke were carried out. Finally, the propagation characteristics of TCRN in the McPherson suspension system connected to the aluminum alloy wheel with a Y-shaped spoke were studied and analyzed by the power flow method under different working conditions. The power flow output via the lower arm front bushing was the largest, while the output via the rear bushing was the smallest in the Y-spoke aluminum alloy wheel and suspension system. The areas in the suspension system with high stress are located at the steering knuckle, lower swing arm, and shock absorber. Therefore, study of the propagation characteristics can provide a basis for a McPherson suspension system design.

Time history iteration algorithm for offline real‐time hybrid testing

AbstractReal‐time hybrid testing (RTHT) is a reliable and efficient method for large‐scale dynamic testing. Unlike online RTHT, offline RTHT allows the computation of the numerical substructure independent of the loading of the experimental substructure, which has obvious advantages in terms of accuracy, stability, and cost. The existing offline RTHT method is difficult to converge in many cases and has a limited range of applications. This paper proposes a new time history iteration (THI) algorithm based on cumulative increments. The increment of the next iteration signal is determined based on the increments of all previous iteration signals. The proposed algorithm can improve the system stability and convergence speed of offline RTHT. The stabilization mechanism and effect of the key parameter were investigated by conducting a series of simulations. Physical tests were performed on structures equipped with a tuned mass damper and an active mass damper. The test results suggest that the proposed THI algorithm can simultaneously consider iterations at all time steps and solve the coupling problem in offline RTHT. The time history iteration is stable and always converges in tests when facing complex situations such as resonance, nonlinearity, closed‐loop control, and measurement noise.

Research on Conditions and Influence Factors of an Acoustic Wave Acting as a Plane Wave in Tire Acoustic Cavity

Tire acoustic cavity resonance noise (TACRN) contributes significantly to the interior noise of electric cars and passenger cars with lower powertrain noise, which affects the comfort of the ride. To suppress TACRN effectively, it is crucial to clarify the characteristics of TACRN. In previous studies, the acoustic wave in the tire acoustic cavity is straightforwardly assumed to be the plane wave for convenience. In fact, there exist strict conditions for the acoustic wave propagating in the pipeline to act as a plane wave. The aim of this paper is to make the characteristics and evolution of acoustic waves in tire acoustic cavities clear. To do so, a simplified model of the tire cavity is established, and the sound field distribution and the acoustic wave propagation characteristics in the tire cavity are analyzed based on the theory of acoustic waveguide. Then, the existence ranges of higher-order waves (non-plane waves), the conditions of an acoustic wave evolving into a plane wave, and the frequency range of a plane wave are investigated. Finally, the characteristics and evolution law of an acoustic wave in a tire acoustic cavity are obtained. The work in this paper may deepen the understanding of the characteristics and mechanism of acoustic waves in the tire cavity and be helpful and meaningful for analyzing and suppressing TACRN. Therefore, it is of practical significance to reduce TACRN transmitted to the vehicle and improve the sound quality inside the vehicle.

Measurements of DC SQUID Damping Effects on Superconducting Resonant Circuits

We present experimental measurements of SQUID-induced damping effects on strongly coupled, lumped-element resonators in the 500kHz-1 MHz frequency range. While dc SQUIDs are commonly used for sensitive readout of electromagnetic signals such as in lumped-element axion dark matter searches, coupling a dc SQUID to a resonant circuit modifies the circuit's resonance frequency, quality factor, noise, and impedance. These parameters have a direct impact on the science reach of axion dark matter detectors, making it important to understand SQUID damping contributions. We describe a helium dip probe and two-stage SQUID readout scheme used to probe SQUID damping effects. Measurements from this setup inform the design and operation of both future test platforms as well as next-generation dark-matter experiments.