Noise Control Research Articles

Optical Time-Domain Quantum State Tomography on a Subcycle Scale

Following recent progress in the experimental application of electro-optic sampling to the detection of the quantum fluctuations of the electromagnetic-field ground state and ultrabroadband squeezed states on a subcycle scale, we propose an approach to elevate broadband electro-optic sampling from a spectroscopic method to a full quantum tomography scheme, able to reconstruct a free-space quantum state directly in the time domain. By combining two recently developed methods to theoretically describe quantum electro-optic sampling, we analytically relate the photon-count probability distribution of the electro-optic signal to a transformed phase-space quasiprobability distribution of the sampled quantum state as a function of the time delay between the sampled midinfrared pulsed state and an ultrabroadband near-infrared probe pulse. We catalog and analyze sources of noise and show that in quantum electro-optic sampling with an ultrabroadband probe pulse one can expect to observe thermalization due to entanglement breaking. Mitigation of the thermalization noise enables a tomographic reconstruction of broadband quantum states while granting access to its dynamics on a subcycle scale. Published by the American Physical Society 2024

Control of Large Wind Energy Converters for Aeroacoustic Noise Mitigation with Minimal Power Reduction

The population is often opposed to wind turbines being erected near their homes, mainly because the machines are noisy, especially at night. In an effort to establish a compromise between the needs of the people and the fulfilment of energy demands, wind turbines have the ability to switch between day and night operation by reducing the rotation speed during the night, resulting in a loss of generated power. The present study investigates simple models for noise emission, propagation, and prediction, with the objective of proposing a control system configuration that continuously adjusts the rotational speed as much as necessary until it matches sound level regulations while minimising power losses. Thus, several approaches are implemented and tested with a very large reference wind turbine. The simulation results of a reference wind turbine show that the approaches provide significant improvements in sound reduction as well as in power conversion.

Active noise control of refrigerator based on cascaded notch feedback algorithm

Refrigerators bring convenience to people, but the noise they produce can also affect people’s lives. Refrigerator noise is dominated by low-frequency noise, and the active noise control method is more effective for this kind of noise. However, the existing active noise control methods for refrigerators do not take into account factors such as the limited space and complex structure of the refrigerator compressor room, and external interference signals will be introduced to affect the noise reduction performance during the error signal collection. Given that, this paper proposes the cascade notch feedback algorithm, which can well reduce the influence of external interference signals to better achieve the refrigerator noise reduction. The algorithm consists of the cascaded notch filtering algorithm and the feedback algorithm. The cascade notch filtering algorithm is formed by cascading the adaptive notch filtering algorithm, which is used to deal with the main frequency and harmonic noise generated by the refrigerator. The feedback algorithm consists of a robust algorithm for dealing with external interference signals introduced during error signal collection. The simulation experiment proves that the algorithm has advantages in terms of noise reduction and computational cost compared with the adaptive notch filtering algorithm and the improved algorithm. The experimental test platform is set up to carry out the actual refrigerator noise reduction experiments under different conditions. The algorithm has the effect of noise reduction under different robust algorithms.

"Split Impact: Road Traffic Directly Strains the Heart, Railway Noise Fuels Metabolic Risk-The Need for Tailored Noise Control".

"Split Impact: Road Traffic Directly Strains the Heart, Railway Noise Fuels Metabolic Risk-The Need for Tailored Noise Control".

Reducing low-frequency noise radiation from a concrete box girder bridge using acoustic short circuits

Low-frequency noise (20–200 Hz) radiated from concrete box girder bridges on urban viaduct railway lines is a significant source of disturbance to nearby residents. Many researchers have investigated methods which can be used to effectively reduce this bridge noise. Currently, most of the methods are based on the principles of vibration isolation and/or absorption. This paper, after modelling and analysing the contributions of various parts of a concrete box girder bridge to the total noise radiated from the bridge, presents a study on the potential in bridge noise control of making holes to create acoustic short circuits on the bridge wings. It is found that by this means the bridge noise can be reduced by up to 6.8 dB at standard-specified measurement points. Additionally, a 3dB-effectiveness distance ratio design method for acoustic short-circuiting is proposed, which effectively reduces bridge noise and achieves stable noise reduction outcomes.

Active Impulsive Noise Control with Missing Input Data Based on FxImdMCC Algorithm

In this study, we address the challenge of noise reduction in environments characterized by impulsive noise and missing input data in active noise control (ANC) systems, where existing algorithms often fail to deliver satisfactory results. Background noise, especially impulsive noise, poses a significant obstacle to signal processing and noise reduction. Furthermore, data loss during transmission or acquisition further complicates the noise reduction task. In this paper, a filtered-x imputation of the missing data maximum correntropy criterion (FxImdMCC) algorithm is proposed based on an imputation model, least mean square, and the maximum correntropy criterion (MCC), which can effectively reduce the impact of outliers and missing input data. The simulation results demonstrate the efficacy of the proposed FxImdMCC algorithm, which significantly outperforms existing algorithms in the context of active impulsive noise control.

Hierarchical meta-porous materials as sound absorbers

The absorption of sound has great significance in many scientific and engineering applications, from room acoustics to noise mitigation. In this context, porous materials have emerged as a viable solution towards high absorption performance and lightweight designs. However, their performance is somewhat limited in the low-frequency regime. Inspired by the concept of recursive patterns over multiple length scales, typical of many natural materials, here, we propose a hierarchical organization of multilayered porous media and investigate their performance in terms of sound absorption. Two types of designs are considered: a hierarchical periodic (HP) and a hierarchical gradient (HG). In both cases, it is found that in some frequency ranges the introduction of multiple levels of hierarchy simultaneously allows for: (i) an increase in the level of absorption compared with the corresponding bulk block of porous material (or to the previous hierarchical levels (HLs)), and (ii) a reduction in the quantity of porous material required. Another advantage of using this approach is on the fabrication, since only one porous material is required. The performances are examined for both normal and oblique incidences, as well as for different values of the static air-flow resistivity. The methodological approach is based on the transfer-matrix method, optimization algorithms such as the metaheuristic greedy randomized adaptive search procedure (GRASP), finite-element calculations and measurements performed in an impedance tube.

Viscoelastic material enhancement of underwater sound absorption in higher-order resonators: from low-frequency to ultra-broadband

Underwater noise control is crucial for improving the marine acoustic environment. This study introduces a novel underwater acoustic absorber design that integrates viscoelastic materials with higher-order resonance structures to enhance the absorption efficiency of low-frequency sound waves. By embedding a thin layer of rubber within a conventional second-order Helmholtz resonator, the rubber's viscoelastic and damping properties significantly improve this structure's underwater low-frequency acoustic performance. Theoretical and simulation calculations have shown that the structure has two perfect absorption peaks in the low-frequency range. The simulation results show that in the frequency range of 415-1848 Hz (Simulation), only four units are needed to effectively absorb up to 90% of noise energy, and the total volume is only. Moreover, the absorber maintains excellent absorption performance over a wide range of incidence angles from 0 to 60 degrees. This work is helpful to design ultra-thin low-frequency underwater absorbers.

Numerical Study of Flow and Noise Control Mechanism of Shape-Optimized Series Cylinder

Numerical Study of Flow and Noise Control Mechanism of Shape-Optimized Series Cylinder

Automatic Noise Monitor and Control in Library

Abstract: This paper introduces imperative to sustain a study-friendly atmosphere in libraries, as noise levels can greatly influence patron satisfaction. In order to reduce noise levels in libraries, this project suggests designing and implementing an autonomous noise monitoring and control system. The device constantly measures ambient noise levels by comparing them to predetermined thresholds using sound sensors and an Arduino. The technology reminds users to keep the environment quiet by sounding alerts and displaying visual cautions when acceptable limits are exceeded. To further reinforce silent norms, automatic audio announcements can be incorporated.

Photodual-Responsive Anthracene-Based 2D Covalent Organic Framework for Optoelectronic Synaptic Devices.

To facilitate the development of efficient neuromorphic perception and computation, it is crucial to explore optoelectronic synaptic devices that integrate perceptual and computational capabilities. Various materials such as oxide semiconductors, conjugated organic polymers, transition metal sulfides, perovskite materials, and metal nanoparticles, along with their composites, are utilized in constructing these devices. However, optoelectronic synaptic devices based on 2D covalent organic frameworks (COFs) is rarely reported. In this study, an anthracene-based 2D COF (COF-DaTp) film is prepared using a room-temperature interface-confined strategy and utilized it as the active layer in an optoelectronic synaptic device with an Al/COF-DaTp/ITO configuration. The device demonstrated dual optoelectronic modulation, exhibiting significant optoelectronic resistive switching in response to light pulses, achieving 32 photoconductive states. Moreover, it exhibited history-dependent memristive behavior in voltage scans and electrical pulses, with a comparable diversity of 32 conductive states. The photodual-responsive properties of the COF-DaTp-based synaptic device enable it to simultaneously perform optical sensing and basic image denoising and recognition tasks, significantly enhancing recognition accuracy and reducing the number of training epochs compared to datasets without noise mitigation. This work opens the door for the application of 2D COF-based optoelectronic synaptic devices in visual computational processing.

Mechanism of airborne sound absorption through triboelectric effect for noise mitigation

Mitigating broadband noise with passive airborne sound absorbers has been a long-lasting challenge, particularly for low-frequency anthropogenic sounds below kilohertz with long wavelengths, which require bulky materials for effective absorption. Here, we propose a strategy that utilizes local triboelectric effect and in-situ electrical energy dissipation mechanism for airborne sound absorption. This approach involves a fundamentally different mechanism that converts airborne sound into electricity for energy dissipation, in contrast to conventional mechano-thermal energy conversion mechanisms. We establish an equivalent acoustic impedance model to provide theoretical analysis of the underlying sound absorption mechanisms, with a theoretical maximum mechano-electro-thermal coupling efficiency approaching 100% under optimal conditions. We design fibrous triboelectric composite foam materials accordingly and show their substantially boosted acoustic absorption performance experimentally, where the adoption of diverse triboelectric material pairs validates that a larger difference in material charge affinities intensifies the local triboelectric effect and results in higher acoustic absorbing performance.

Robust continuous-variable quantum key distribution in the finite-size regime

Quantum key distribution (QKD) has been proven to be theoretically unconditionally secure. However, any theoretical security proof relies on certain assumptions. In QKD, the assumption in the theoretical proof is that the security of the protocol is considered under the asymptotic case where Alice and Bob exchange an infinite number of signals. In the continuous-variable QKD (CV-QKD), the finite-size effect imposes higher requirements on block size and excess noise control. However, the local local oscillator (LLO) CV-QKD system cannot be considered time-invariant under long blocks, especially in cases of environmental disturbances. Thus, we propose an LLO CV-QKD scheme with time-variant parameter estimation and compensation. We first establish an LLO CV-QKD theoretical model under the temporal modes of continuous-mode states. Then, a robust method is used to compensate for arbitrary frequency shift and arbitrary phase drift in CV-QKD systems with longer blocks, which cannot be achieved under traditional time-invariant parameter estimation. Besides, the digital signal processing method predicated on high-speed reference pilots can achieve a time complexity of O(1). In the experiment, the frequency shift is up to 89.05 MHz/s and phase drift is up to 3.036 Mrad/s using a piezoelectric transducer (PZT) to simulate the turbulences in the practical channel. With a signal-to-interference ratio (SIR) of −51.67 dB, we achieve a secret key rate (SKR) of 0.29 Mbits/s with an attenuation of 16 dB or a standard fiber of 80 km. This work paves the way for future long-distance field-test experiments in the finite-size regime.

Study on need of monitoring sound pollution at developing urban localities

Environmental pollution is a very serious issue around the world due to development of humankind towards well-being and modernization. It not only impacts health but also affects over all biodiversity. Sound does nothing till it is up to certain limit, as it creates pressure on the particles of the medium, when the limit of pressure is increased, it becomes nuisance. Sound pollution is the one important agent out of other factors that disrupts the living of humans and its ecosystem. It is related with physical, psychological or emotional states. Sound pollution adversely affects the humankind and animals leading to irritation, loss of concentration, and loss of hearing and abnormal behaviour of animals. The present work emphasizes the need to monitor and control the sound pollution in the developing cities to tackle the related future problems, to investigate the status and validity of ambient noise standards in the Indian situation, also to propose need of noise control based on the available knowledge on noise policies and regulations. The study is an approach towards importance of monitoring the sound pollution, its sources and its effects on the human activities or the ecosystem with respect to degrees of exposure in the newly developing urban localities with moderate commercial activities. The impact of sound pollution will increase if appropriate measures are not taken.

Optimized Noise Suppression for Quantum Circuits

Quantum computation promises to advance a wide range of computational tasks. However, current quantum hardware suffers from noise and is too small for error correction. Thus, accurately utilizing noisy quantum computers strongly relies on noise characterization, mitigation, and suppression. Crucially, these methods must also be efficient in terms of their classical and quantum overhead. Here, we efficiently characterize and mitigate crosstalk noise, which is a severe error source in, for example, cross-resonance based superconducting quantum processors. For crosstalk characterization, we develop a simplified measurement experiment. Furthermore, we analyze the problem of optimal experiment scheduling and solve it for common hardware architectures. After characterization, we mitigate noise in quantum circuits by a noise-aware qubit routing algorithm. Our integer programming algorithm extends previous work on optimized qubit routing by swap insertion. We incorporate the measured crosstalk errors in addition to other, more easily accessible noise data in the objective function. Furthermore, we strengthen the underlying integer linear model by proving a convex hull result about an associated class of polytopes, which has applications beyond this work. We evaluate the proposed method by characterizing crosstalk noise for two chips with up to 127 qubits and leverage the resulting data to improve the approximation ratio of the Quantum Approximate Optimization Algorithm by up to 10% compared with other established noise-aware routing methods. Our work clearly demonstrates the gains of including noise data when mapping abstract quantum circuits to hardware native ones. History: Accepted by Giacomo Nannicini, Area Editor for Quantum Computing and Operations Research. Accepted for Special Issue on Quantum Computing. Funding: This work was supported by Bavarian state government; Bayerische Staatsministerium für Wirtschaft, Landesentwicklung und Energie. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information ( https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2024.0551 ) as well as from the IJOC GitHub software repository ( https://github.com/INFORMSJoC/2024.0551 ). The complete IJOC Software and Data Repository is available at https://informsjoc.github.io/ .

The knowledge of medical staff on the impact of noise on neonatal intensive care units patients and its application in practice.

Noise is an undesirable environmental factor whose control and reduction should be standard in every Neonatal Intensive Care Unit. Its impact can have negative effects on both the mental and physical health of the body. Newborns, especially premature infants, are particularly sensitive to the negative effects of noise. the negative impact of noise can be reduced through appropriate behaviour of the medical staff. Aim. The aim of the study is to analyse the knowledge of medical staff on the impact of noise on newborns staying in Neonatal Intensive Care Units and to evaluate its use in practice. Methods. A total of 104 respondents working in neonatal wards participated in the study. The survey was conducted online using social media. The study employed the diagnostic survey method with a self-designed questionnaire. The first part of the ques- tionnaire concerned the aspects of knowledge on the impact of noise on hospitalised new- borns; the second part addressed the socio-demographic issues of the medical staff. Results. Training on noise exposure for newborns is not common in the workplace. There are no recommendations regulating noise standards and control equipment. The surveyed individuals do not have in-depth knowledge about acceptable noise levels in newborn rooms. Only one in three employees was able to provide the correct answers in this regard. Older employees with longer experience and residents of large cities scored higher in knowledge than younger individuals. Those with a higher level of knowledge and satisfaction with their work and earnings show the greatest care in reducing noise intensity in the ward. Conclusions. In neonatal pathology wards and (NICUs), noise standards and recom- mendations are more common than in physiology wards. Employees caring for new- borns need training on the sources and impact of noise on babies. it is necessary to limit the noise generated by the staff, such as loud conversations, slamming furniture, placing objects on incubators, or moving equipment.

Methods for separating the noise produced by the wheels and track during a train pass-by

AbstractRolling noise is produced by vibration of the wheels and track, induced by their combined surface roughness. It is important to know the relative contributions of the different sources, as this affects noise control strategies as well as acceptance testing of new rolling stock. Three different techniques are described that aim to use pass-by measurements to separate the wheel and track components of rolling noise. One is based on the TWINS model, which is tuned to measured track vibration. The second is based on the advanced transfer path analysis method, which provides an entirely experimental assessment. The third is based on the pass-by analysis method in combination with static vibroacoustic transfer functions which are obtained using a reciprocity method. The development of these methods is described and comparisons between them are presented using the results from three experimental measurement campaigns. These covered a metro train, a regional train and a high-speed train at a range of speeds. The various methods agree reasonably well in terms of overall trends, with moderate agreement in the mid-frequency region, and less consistent results at low and high frequency.

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.

Experimental and numerical study on underwater noise control of multigrooved metasurface coating with antifouling and drag reduction potential

Acoustic metasurfaces have garnered increasing attention due to their efficacy in low-frequency sound absorption, while achieving broadband sound absorption performance remains challenging. In this study, a novel approach employing a multigrooved metasurface integrated onto a nanocomposite material is undertaken. Before modification, the nanocomposite material exhibits commendable underwater sound absorption capabilities above 4000 Hz, but demonstrates lower performance below this threshold. Integrating the multigrooved metasurface yields a notable enhancement in sound absorption performance below 4000 Hz, with the average absorption coefficient increasing from 0.29 to 0.63. Remarkably, this enhancement almost does not impact the performance above 4000 Hz. Experimental findings additionally reveal improved performance under variable hydrostatic pressures. Notably, the multigrooved surfaces show enhanced antifouling properties, and also exhibit potential for drag reduction compared to smooth surfaces. The proposed multigrooved metasurface in this study introduces a novel strategy towards the development of multifunctional underwater sound absorption coatings.

Multi-innovation adaptive Kalman filter algorithm for estimating the SOC of lithium-ion batteries based on singular value decomposition and Schmidt orthogonal transformation

The state of charge (SOC) of lithium battery is a key parameter for effective management of battery management systems (BMS). To address the problems of low precision, complex computation and poor robustness of traditional charging state estimation methods, an enhanced algorithm based on Unscented Kalman filter (UKF) is proposed. The singular value decomposition (SVD) method is adopted to ensure the normal operation of the Unscented Kalman Filter (UKF) algorithm even when the matrix P lacks positive semi-definiteness from a mathematical perspective. This enhancement significantly improves the theoretical robustness of UKF. Schmidt orthogonal transformation is concurrently used to reduce the computational complexity in the sampling point selection process, and the multi-innovation theory is combined with adaptive noise control to further improve the accuracy of SOC estimation. The algorithm is validated using the Urban Dynamometer Driving Schedule (UDDS) condition. The simulation results are excited using Singular value decomposition-multi-innovation adaptive Schmidt orthogonal unscented Kalman filter method (SVD-MIASOUKF). 0.95 % and 1.29 % of maximum errors are obtained at 25 °C and −10 °C, while the maximum errors are 2.46 %–2.99 % using SVD-UKF and UKF. The proposed approach shows faster convergence speed and higher estimation accuracy in comparison to traditional algorithms.