Attenuation Performance Research Articles

A multi-function glass shield for neutrons and gamma rays of boron- and bismuth-reinforced silicate glass

A successful attempt to produce a multi-function glass shield for attenuating neutrons and gamma rays by reinforcing a silicate glass network with boron and bismuth has been accomplished. A composition of 20SiO2-80Na2O (BSiBi0) was proposed to be used as a host glass network and prepared using the melt/annealing techniques. The low concentration of SiO2 in BSiBi0 was not sufficient to form a stable glass network. Then, the proposed BSiBi0 was modified with 10, 20, 30, and 40 mol% of each of B2O3 and Bi2O3 (BSiBi1, BSiBi2, BSiBi3, and BSiBi4) simultaneously. The structural effects of adding B3+ and Bi3+ were studied through X-ray diffraction, density, and FTIR, which all showed enhancement of glass forming ability, a former role of Bi3+ ions, and crowded the glass network by BO4 units. The derived structural parameters -\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-$$\\end{document} molar volume, mean silicon – silicon separation, mean boron – boron separation, oxygen packing density, packing density, and number of bridging/non-bridging oxygen -\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-$$\\end{document} were extensively discussed to explore the impact of B3+ and Bi3+ on the formed network. The richness of the proposed host glass network by B3+ and Bi3+ enhanced its thermal stability. The obtained elastic properties by ultrasonic measurements reflect the increase of the glass rigidity with increasing concentrations of B3+ and Bi3+ ions. The obtained glasses have high visible light transparency and almost complete UV absorption. The measured shielding parameters against two types of neutron energies (total slow and slow) and a wide range of gamma rays’ energies showed a significant improvement in the shielding efficiency of the considered glasses. The total slow neutrons, slow neutrons, and gamma rays’ attenuation abilities were improved by 22.9, 135.5, and 73.8 -\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-$$\\end{document} 199.5%. High thermal stability, elasticity, visible light transparency, and neutrons and gamma rays’ attenuation performance features give the produced glasses, especially BSiBi4 glass, preference as shielding materials in nuclear fields.

Gamma attenuation and radiation shielding performance of CaCu3B2Re2O12 (B[dbnd]Mn, Fe, Co, and Ni) perovskites

In order to identify the importance of perovskites in nuclear science, studies aimed at obtaining the radiation interaction quantities of perovskites are essential. This study computed and analyzed the gamma photon interaction parameters of CaCu3B2Re2O12 (BMn, Fe, Co, and Ni) perovskites to reveal their shielding potentials and comparative advantages against traditional shielding materials. Four samples of ferrimagnetic quaternary perovskites whose chemical structures are summarized as CaCu3B2Re2O12 (BMn (CCMRO1), Fe (CCMRO2), Co (CCMRO3), and Ni (CCMRO4)) were considered for their gamma interaction quantities. The values of mass attenuation coefficient (μρ) was calculated with XCOM and they were in the range of 0.0552 cm2/g–0.4162 cm2/g for CCMRO1, 0.0553 cm2/g–0.4165 cm2/g CCMRO2, 0.0552 cm2/g–0.4148 cm2/g for CCMRO3, and 0.0555 cm2/g–0.4163 cm2/g for CCMRO4. The values of effective atomic number and electron density was within the range 21.38–43.38 and 2.84 x 1023 electrons/g −5.62 x1023 electrons/g, respectively. The trend of the mass energy absorption coefficients of the perovskites was also found to be in the same order as the mass attenuation coefficient. CCMRO3 has the highest photon energy absorptive ability among the perovskites while CCMRO2 has the least capacity. Also, the gamma dose rates in15 mm thick of CCMRO1, CCMRO2, CCMRO3, and CCMRO4 for 1.25 MeV are about 1446 kR/h, 1449 kR/h, 1453 kR/h, and 1446 kR/h, respectively. Comparatively, the values of the exposure and energy absorption buildup factors were almost the same for the perovskites at the same energy and optical depth. The investigated perovskites had higher mass attenuation coefficients that standard shielding glasses. The perovskites can be used for shielding or any other radiation absorption roles in radiation science and technology, especially for photons at low energies.

Smart whole-body vibration attenuation, cushion for heavy equipment seating: Model and simulation

Off-road mobile machine operators are exposed to whole-body vibration (WBV) which can result in adverse health effects. Seat suspensions are used to reduce WBV exposure, but typical passive seats cannot attenuate frequencies below 1.13 Hz. The proposed device is designed to minimize transmissibility from 0 to 20 Hz because this bandwidth contains the dominant frequency for most off-road vehicles. The semi-active smart device uses bang-bang control and is designed to be installed in place of the seat-pan cushion in OEM passive seats. Modelled as a two degree of freedom system, simulations were performed using a lumped mass model (ωn = 3 Hz; sinusoidal base excitation 0-20 Hz). Using a hexapod robot, a prototype reduced transmissibility compared to a passive OEM seat. The device was up to 5 times more effective than a passive seat in reducing vibration transmissibility. Simulations revealed that operator mass and seat stiffness variations have little effect on device WBV attenuation performance.

Numerical study of acoustic metamaterial made of Helmholtz resonators with complex necks for low frequencies noise attenuation

In this paper, an acoustic metamaterial consisting of Helmholtz resonators with complex necks is proposed for low frequency noise reduction. The resonators are made of a cavity and a complex neck, which is a periodic succession of necks with small and large diameters. The acoustic attenuation performance of the proposed metamaterial design is demonstrated using finite element method. For such a shaped neck, the sound absorption coefficient presents multiple peaks. With a succession of N small and (N - 1) large neck diameters, N peaks in the sound absorption coefficient are obtained. By increasing the number of successions, the number of peaks increases. At the peaks, the surface acoustic impedance of the metamaterial nearly matches with the characteristic impedance of the air. This makes the sound absorption coefficient being nearly 100%. Keeping the same cavity volume, we increase the number of sound absorption peaks by the complex shape of the neck, while the classic Helmholtz resonator presents only one peak.

Revision of Japanese guidelines for the prevention of noise-induced impairments in 2023

In Japan, the guideline for the prevention of noise-induced impairments published in 1984 was revised in 2023. The revisions include changes to the definition of target workplaces, methods for measuring noise levels, and methods for selecting hearing protection equipment. Additionally, prior to the revision of the guidelines, Japanese industrial standard (JIS) regarding the method for measuring the sound attenuation performance of hearing protectors was established in 2020. The old JIS was a product standard, but it was changed to a method standard with the ISO standard as an international standard. The new JIS has adopted single number rating (SNR) as an evaluation index. In recent years, Japan's guidelines and standards related to occupational noise have been internationally harmonized, but currently they are only published in Japanese. In this paper, an overview of the guidelines for the prevention of noise-induced impairments revised in 2023 will be mainly presented. This paper also introduces measuring device for noise exposure level, fit testing equipment, and real-ear attenuation at threshold (REAT) testing currently available in Japan. An overview of the new JIS was previously reported at inter-noise conference in 2021.

Sound transmission loss of constrained layer damping composites featuring elastic plates embedded with acoustic black hole

This paper preliminarily investigates the influence of an elastic layer with an acoustic black hole (ABH) on the airborne sound insulation of a constrained layer damping (CLD) composite plate. ABHs represent a continuous impedance reduction in a local area of the structure, achieved by reducing material thickness. They efficiently dampen structure-borne sound in plate-like structures, resulting in excellent airborne sound attenuation performance. In the CLD composite structure, a damping layer is inserted between the elastic layers. This configuration achieves noise reduction and provides excellent airborne sound attenuation performance. By incorporating an ABH on one side of the elastic layer within the constrained damping composite structure and utilizing the damping layer as the terminal damping material for ABH, we achieve a lightweight structure with outstanding airborne sound insulation performance. Using finite element numerical calculations, we assess the airborne sound transmission loss of ABHs embedded within the CLD plate. Our analysis compares their transmission losses within the frequency range of 10 to 4000 Hz under normal-incidence and random incidence acoustic field excitations. While the ABH does not enhance the overall sound isolation performance of the CLD plate, it significantly improves the sound isolation dip at the resonance frequency.

Experimental evaluation of the impact of ZnO on the radiation shielding ability of B2O3–PbO–ZnO–CaO glass systems

In this study, we used the melt quenching process to develop inexpensive, new radiation shielding glasses. The prepared glasses have a general formula 40B2O3–20PbO-(y)ZnO-(40-y)CaO, (y = 20, 25, 30 and 35 mol%). These glasses' gamma-radiation shielding properties were experimentally measured using Am-241, Co-60, and Cs-137 sources and a High-Purity Germanium (HPGe) detector, revealing that incorporation of ZnO had a positive impact of the density of these glasses. Moreover, the incorporation of ZnO enhanced the prepared glasses' attenuation performance. With greater energy the half value layer increased, and by a factor of 45 with a 0.059–1.333 MeV energy increase. For the four studied glasses the radiation protection efficiency (RPE) values are 100 % efficient at low energies (0.059 MeV), with a drastic decrease in the values across all four samples as the energy increases from 0.06 to 0.662 MeV.

Radiation Shielding Properties of Nickel, Copper and Iron Based Alloys

This study explores the radiation shielding properties of Iron-based and Nickel-based alloys with Cobalt composition to evaluate their performance in photon attenuation and shielding applications. The objectives of this work are to determine linear and mass attenuation coefficients (LAC, MAC), half and tenth value layers (HVL, TVL), mean free path (MFP), effective atomic number and electron density (Zeff, Neff), effective conductivity (Ceff), atomic cross section (ACS) and electronic cross section (ECS) of nickel and iron base alloy with Cobalt using Phy-X/PSD within 0.001 MeV to 10 MeV. The result shows Iron and Nickel-based alloys have electron densities around 10²³ electrons per gram, with increased Iron concentration improving low-energy photon attenuation. Nickel-based alloys have a higher MAC and LAC compared to Iron-based oxides, indicating better photon absorption per unit mass and thickness, respectively. Nickel-based alloys exhibit a lower HVL and TVL, indicating greater attenuation and absorption efficiency for photons, especially at lower energies. Conversely, Iron-based alloys, while showing higher HVL and TVL. Nickel-based alloys exhibited higher electron densities the Iron-based alloys and Zeff values for Nickel based alloys, ranging from 27.1 to 27.8 while Iron-based alloys with Zeff between 26.2 and 26.8. Ceff in Iron-based alloys was stable at (1.50 to 1.74) x 10⁹ S/m, while Nickel-based alloys showed significant fluctuations below 0.01 MeV. Nickel-based alloys also had higher ACS and ECS, indicating superior photon interaction, especially at lower energies. These results highlight Nickel based alloys' greater efficacy in low-energy photon attenuation and the stable performance of Iron based alloys at higher energies.

Analytical modeling of piezoelectric meta-beams with unidirectional circuit for broadband vibration attenuation

Broadband vibration attenuation is a challenging task in engineering since it is difficult to achieve low-frequency and broadband vibration control simultaneously. To solve this problem, this paper designs a piezoelectric meta-beam with unidirectional electric circuits, exhibiting promising broadband attenuation capabilities. An analytical model in a closed form for achieving the solution of unidirectional vibration transmission of the designed meta-beam is developed based on the state-space transfer function method. The method can analyze the forward and backward vibration transmission of the piezoelectric meta-beam in a unified manner, providing reliable dynamics solutions of the beam. The analytical results indicate that the meta-beam effectively reduces the unidirectional vibration across a broad low-frequency range, which is also verified by the solutions obtained from finite element analyses. The designed meta-beam and the proposed analytical method facilitate a comprehensive investigation into the distinctive unidirectional transmission behavior and superb broadband vibration attenuation performance.

Lightweight composites derived from carbonized taro stems for microwave energy attenuation and thermal energy storage

A novel strategy has been developed for preparing porous carbon materials derived from taro stems, aimed at enhancing electromagnetic wave (EMW) attenuation and thermal energy storage. The materials were synthesized through the carbonization of taro stems to form a porous carbon structure, subsequently enhanced with polyethylene glycol (PEG) containing carbon nanotubes (CNTs) and nickel (Ni) nanoparticles. By adjusting the carbonization temperature and the loading of CNTs and Ni, the resulting carbon materials exhibited exceptional EMW attenuation performance. Specifically, the PC-800 sample demonstrated a remarkable minimum reflection loss of −61.4 dB across the frequency range of 8.2–11 GHz, with a low density of 0.054 g/cm³. The PC-1200 sample exhibited EMI SE values of 23.6 dB axially and 21.5 dB radially in the X-band, with an ultra-low density of 0.033 g/cm³. Further enhancements were observed in the PC/CNT2 and PC/CNT2-Ni15 composites, achieving EMI SE values of 26.3 dB and 26.8 dB, respectively. Additionally, these composites exhibited effective thermal energy storage and release, as confirmed by heating experiments. This study not only introduces a method for creating absorption-dominated biomass electromagnetic shielding materials but also provides a dual-functional solution for enhancing the performance of electronic devices.

Experimental Analysis of Noise Characteristics on Different Types of Pavements inside and outside Highway Tunnels

Aiming to reduce noise pollution and optimize the acoustic quality in highway tunnels, the noise characteristics on different types of pavements were analyzed and compared in this research, based on the on-site noise measurement in two tunnels with the free fields as a control group. Specifically, the noise characteristics include two aspects: various noise and noise time attenuation performance. Various noise includes on-board sound intensity (OBSI) noise and cabin noise. The noise time attenuation performance uses the indicator of reverberation time. Three types of pavements were measured, including dense-graded asphalt concrete (DAC) and single-layered and double-layered porous asphalt (PA) pavement. The results showed that, for the same type of pavement, compared with the free fields, the difference in OBSI noise in tunnels was within a range of less than 1 dBA; the cabin noise increased by 3.4 dBA~6.6 dBA. The noise level in tunnels was greater than that outside tunnels, and the longer tunnel exhibited higher traffic noise and worse noise time attenuation performances. For the same tunnel, PA pavement could reduce the cabin noise by 3.8 dBA~6.7 dBA. PA pavement also exhibited shorter reverberation time. The application of PA pavement could effectively improve the acoustic quality in the tunnel. This research contributes to noise pollution abatement and the improvement of the comfort and safety of drivers in tunnels.

Deep-learning-based generative design for optimal reactive silencers

A deep-learning-based generative design method is proposed to improve the frequency-dependent characteristics of a reactive silencer, and it has been validated both numerically and experimentally. The noise attenuation performance of the reactive silencer is evaluated with its transmission loss (TL), which varies with frequency and strongly depends on the partition layout inside the reactive silencer. The artificial neural network model for the generative design of the reactive silencer consists of three subnetwork models: the generator, predictor, and converter. The generator model created numerous partition layouts, and their TL curves were estimated using the predictor model. A converter model was developed to identify the frequency-dependent characteristics of the TL curves in a low-dimensional latent space. The latent space was extensively investigated to successfully select the optimal partition layouts satisfying given design requirements, including the target shape of the TL curve and its averaged target TL value. The effectiveness of the proposed method was demonstrated by applying it to three reactive silencer design problems with different design requirements. Among the three optimal silencers, one was physically investigated, and its noise attenuation performance was validated with an acoustic experiment. Because the artificial neural network model of the proposed method was developed for a normalized silencer and requires no prior knowledge of acoustics, it can be easily applied to reduce duct noise in the industry.

Effect of hybrid lead-PVA fibers on microstructure and radiation shielding properties of high-performance concrete

With the widespread application of nuclear technology in the medical and energy fields, the demand for efficient radiation shielding materials is increasing. Employing only lead or polyvinyl alcohol (PVA) fiber reinforcement cannot achieve improvements in the brittleness of high-performance concrete (HPC) while also enhancing radiation shielding efficiency and mechanical properties. This study develops a novel HPC for radiation attenuation, incorporating magnetite as the aggregate and reinforced with hybrid lead-PVA fibers (RSHPC). The synergistic effects of various proportions of hybrid lead-PVA fibers on the mechanical properties, three-dimensional microstructure, pore structure, and interfacial transition zone (ITZ) were investigated. In addition, the radiation attenuation capacities of RSHPC with different hybrid lead-PVA fiber proportions were evaluated through experimental and simulation analysis. The results show that hybrid lead-PVA fibers notably improve the air-void structure of RSHPC. The incorporation of PVA fibers, by improving the ITZ of matrix, effectively mitigates the negative impact of lead fibers on mechanical performance. The refinement of pore structure and the introduction of light and heavy nuclides lead to a significant enhancement in the gamma-ray and neutron radiation attenuation capabilities of RSHPC. Utilizing X-ray computed tomography (X-CT) for three-dimensional reconstruction further indicates the optimization impact of hybrid lead-PVA fibers on the microstructure, notably in the improvement of pore distribution and fiber dispersion, thus enhancing the overall properties and radiation attenuation performance of RSHPC.

Performance analysis of a novel hybrid device with floating breakwater and wave energy converter integrated

As a kind of clean energy, wave energy has attracted increasing attention in recent years. However, due to its high cost and low efficiency, wave energy has not been widely commercialized worldwide. According to previous research works, the combination of wave energy devices and floating breakwaters can reduce the cost of wave power generation devices efficiently. In this paper, a hybrid device with wave energy converter (WEC) and flexible porous floating breakwater integrated is proposed. The hydrodynamic performance of this device is studied by numerical simulation based on Reynolds-Averaged Navier–Stokes (RANS) method which has been validated through experimental results. Based on this, a series of numerical simulations are performed under different power take-off stiffness (KPTO) and different power take-off damping coefficient (CPTO) to calculate the motion and transmission coefficient of the device. By comparing the numerical results, the influence of KPTO and CPTO of the hybrid device on its wave attenuation performance and energy conversion efficiency are analyzed. The results indicate that under the incident waves of period 0.56 s and 0.89 s, the recommended value of KPTO is 3.0 N/m and 0.5 N/m respectively. While for incident waves of period 0.56s, in order to achieve better wave attenuation performance and power generation efficiency, the recommended value of CPTO should be between 10.55 Ns/m and 14.23 Ns/m. On this basis, the influence of the size of breakwater on the wave attenuation performance and power generation efficiency of the hybrid device is also discussed. Moreover, through a cost analysis, it can be inferred that the utilization of the baseline model is more economically viable.

Dynamic Characteristics of Pressure-Balanced Metal Bellows in Fluid–Structure Interaction

As a flexible component in high-pressure vessels and pipeline systems, bellows experience significant fluid–structure interaction effects under high-speed internal fluids and external vibrations. Nevertheless, their dynamic response mechanisms coupled with fluid–structure interaction mentioned below have not yet been clarified so far. In this work, a novel pressure-balanced metal bellow (PBMB) for low-stiffness and high-pressure resistance is firstly proposed. Several fluid–structure interaction models were considered to study the dynamic response characteristics of the PBMB. An experimental platform associated with fluid–structure interaction was established to validate the effectiveness of its vibration attenuation performance. The results indicate that the PBMB has an obvious vibration attenuation effect in the range of 5–90[Formula: see text]Hz, and super-harmonic and sub-harmonic resonance phenomena occur in the range of 90–200[Formula: see text]Hz. Under constant fluid conditions, fluid density, viscosity, flow velocity, and pressure are positively correlated with the response amplitude of the PBMB. The response of the PBMB oscillates at the fluid entry point due to both pulsating flow velocity and pulsating pressure. After several cycles, the response caused by pulsating flow velocity gradually decays and stabilizes. Thus, the impact of pulsating frequency on the stability of the response of bellows is insignificant during the initial cycles.

Observer-based quantized control for networked interconnected PDE systems with actuator failures

This paper proposes an observer-based quantized controller for parabolic partial differential equation systems interconnected by a nonlinear coupling protocol. First, a Markov jump model is introduced to describe various randomly occurring actuator failures, and an observer-based pointwise controller is designed under the averaged measurement scheme. Furthermore, taking into account the limitation of network communication resources, a quantization method is adopted to relieve bandwidth pressure. In addition, stability conditions of the closed-loop system with ℋ∞ disturbance attenuation performance are derived by utilizing appropriate Lyapunov functional and inequality techniques. Ultimately, the proposed method is applied to the Fisher equation to verify its feasibility and effectiveness.

Lightweight and thermally insulating ZnO/SiCnw aerogel: A promising high temperature electromagnetic wave absorbing material with oxidation resistance

Enhancing the microwave attenuation performance under high-temperature and oxidative conditions is a forefront issue for electromagnetic absorption materials. SiC nanowire material exhibits great potential due to its superior thermal stability and oxidation resistance. While, the relatively poor dielectric loss limits its further application as a high effective absorber. In this study, the strategy of laminated porous structure design, as well as the composition of ZnO nanocrystals were applied to promote the microwave attenuation capacity. A simple dual hydrolysis reaction method was employed to grow ZnO nanocrystals on SiC nanowires, followed by the preparation of a 3D layered structure of ZnO/SiCnw aerogel material using directional solidification processes. The ZnO/SiCnw aerogel demonstrated effective broadband attenuation (>90 %) across the entire X-band from room temperature to 873 K. Moreover, the material chemistry remained constant at temperatures as high as 1073 K in air. It exhibited ultralightweight properties and possessed a low thermal conductivity of approximately 0.056 W/m·K, with a density of 0.167 g/cm3. The combination of its lightweight, oxidation resistance, thermal insulation, and attractive X-band absorption efficiency positions ZnO/SiCnw aerogel as a promising EM absorption candidate at both room and high temperatures.

Development of a semi-active suspension using a compact magnetorheological damper with negative-stiffness components

Semi-active suspension with traditional magnetorheological (MR) dampers can attenuate vehicle’s vibration with less power consumption and high stability, nevertheless, it is not as effective as an active suspension. To further improve its vibration attenuation performance, this paper proposes a new MR damper with compact negative-stiffness components and analyses the effect of negative-stiffness characteristics on vibration attenuation performance. Its primary advantages include its high compactness which enables the suspension to be installed into the very limited space of real vehicles without any configuration change, and also its high effectiveness on reducing the vibrations as well as improving the vehicle stability. Upon the design of the new MR damper, a theoretical model and a mechanical model for the compact negative-stiffness component and the MR damper piston is established, respectively, to determine the suitable size of the negative-stiffness component and to optimize the parameters of the piston. Then the mechanical performance of the proposed new MRF damper is verified through an MTS machine. Finally, the new MR damper was mounted on a quarter-car system to evaluate its vibration attenuation performance under sky-hook algorithm by subjecting to different excitations. The experimental results demonstrated that the compact negative-stiffness MR damper has excellent vibration attenuation performance comparable to that of the active suspension.

Robust seismic data denoising via self-supervised deep learning

Seismic data denoising is a critical component of seismic data processing, yet effectively removing erratic noise, characterized by its non-Gaussian distribution and high amplitude, remains a substantial challenge for conventional methods and deep-learning (DL) algorithms. Supervised learning frameworks typically outperform others, but they require pairs of noisy data sets alongside corresponding clean ground truth, which is impractical for real-world seismic data sets. In contrast, unsupervised learning (UL) methods, which do not rely on ground truth during training, often fall short in performance when compared with their supervised or traditional denoising counterparts. Moreover, current unsupervised DL methods fail to address the specific challenges posed by erratic seismic noise adequately. This paper introduces a novel zero-shot unsupervised DL framework designed specifically to mitigate random and erratic noise, with a particular emphasis on blended noise. Drawing inspiration from Noise2Noise (N2N) and data augmentation principles, we develop a robust self-supervised denoising network called robust Noiser2Noiser. Our approach eliminates the need for paired noisy and clean data sets as required by supervised methods or paired noisy data sets as in N2N. Instead, our framework relies solely on the original noisy seismic data set. Our methodology generates two independent recorrupted data sets from the original noisy data set, using one as the input and the other as the training target. Subsequently, we use a DL-based denoiser, denoising convolutional neural network, for training purposes. To address various types of random and erratic noise, the original noisy data set is recorrupted with the same noise type. Detailed explanations for generating training input and target data for blended data are provided. We apply our network to synthetic and real marine data examples, demonstrating significantly improved noise attenuation performance compared with traditional denoising methods and state-of-the-art UL Codes are available on https://github.com/Ji-seismic/N2N_deblending .

Investigating and exploiting the impact of variability in resonator parameters on the vibration attenuation in locally resonant metamaterials.

Locally resonant metamaterials (LRMs) have recently emerged in the search for lightweight noise and vibration solutions. These materials have the ability to create stop bands, which arise from the sub-wavelength addition of identical resonators to a host structure and result in strong vibration attenuation. However, their manufacturing inevitably introduces variability such that the system as-manufactured often deviates significantly from the original as-designed. This can reduce attenuation performance, but may also broaden the attenuation band. This work focuses on the impact of variability within tolerance ranges in resonator properties on the vibration attenuation in metamaterial beams. Following a qualitative pre-study, two non-intrusive uncertainty propagation approaches are applied to find the upper and lower bounds of three performance metrics, by evaluating deterministic metamaterial models with uncertain parameters defined as interval variables. A global search approach is used and compared with a machine learning (ML)-based uncertainty propagation approach which significantly reduces the required number of simulations. Variability in resonator stiffnesses and masses is found to have the highest impact. Variability in the resonator positions only has a comparable impact for less deep sub-wavelength designs. The broadening potential of varying resonator properties is exploited in broadband optimization and the robustness of the optimized metamaterial is assessed.This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 2)'.