Reduce Noise Levels Research Articles

Use of metamaterials to reduce underwater noise generated by ship machinery

Reducing underwater noise pollution from ship machinery is a significant challenge. Ship machinery usually operates at fixed speeds and emits tonal noise with large amplitudes at low frequencies. Conventional soundproofing materials are inadequate for absorbing tonal noise and require large thicknesses at low frequencies. Quarter-wavelength resonators effectively absorb sound at their fundamental frequency and odd harmonics. Still, the applicability of this solution is nevertheless limited by its length requirement, which becomes cumbersome at low frequencies and, thus, large wavelengths. This study explores different structured metamaterial designs based on labyrinth, coiled quarter-wavelength resonators, and hybrid configurations combining glass wool and coiled resonators. Analytical, numerical calculations, and experimental tests are carried out under normal plane wave incidence (using an impedance tube) and a diffuse acoustic field (in a small reverberant cabin). In particular, a numerical optimization based on a periodic unit cell model is used to optimize the hybrid configuration and analyze its behavior under variable plane wave incidence angles. Preliminary tests conducted in a water basin using a small, straightforward aluminum box equipped with some proposed designs indicate reductions in underwater noise levels. The proposed solutions offer limited-cost and compact solutions for mitigating machinery noise and, potentially, the preservation of marine ecosystems.

Acoustic Performance of Porous Mortar and Potential Use for Traffic Noise Mitigation: A Review

Porous mortar (PM) is a porous building material used to reduce noise levels in economic emerging cities to achieve acoustic comfort. This research paper provides a comprehensive review of PM’s sound absorption performance as reported in selected published works. The selection criteria are limited to experiments conducted on specimens with a thickness ranging from 20 to 75 mm, a range suitable for application as a sound-absorbing layer on noise barriers or building walls. This paper explains the underlying principles of sound absorption in PM and outlining methods for assessing sound absorption. This review paper includes the performance of conventional or typical PM with modified PM, considering elements such as mix design and significant factors that influence sound absorption, notably material density, and pore size. Subsequently, this paper reveals on the evaluation of PM’s suitability as a sound-absorbing material, encompassing an assessment of its mechanical properties. In conclusion, the paper identifies the potential of PM as an efficient sound absorber, particularly in the context of mitigating traffic-generated noise.

Beyond Park Boundaries: Exploring The Effect of Surrounding Land Use on Sound Levels of ParksBeyond Park Boundaries: Exploring The Effect of Surrounding Land Use on Sound Levels of Parks

Urban parks in big cities can help reduce noise while providing spaces for recreation and rest, but their size, location and surroundings can limit their environmental benefits. This article will discuss how surrounding land use affects noise levels in a particular park, as well as how park landscaping can limit noise exposure. Four study areas were selected from Kuala Lumpur and Putrajaya to highlight a range of land uses, locations and park sizes. The sound levels were measured twice for each site-morning and evening-using measurement points along the park path and the SL-5868P sound level meter. The results showed that the study area exceeded the recommended noise limit of 55dBA as stipulated by Malaysian Noise Limit and World Health Organization guidelines. In addition, there was a pattern of influence on the measured noise levels based on land use and landscape around the park. Parks located in dense land use have higher noise levels, but have lower variation in noise levels within the park due to higher surrounding noise levels, compared to parks with more than 87% tree cover. The KLCC park, with 76% tree cover, has an overall higher noise level of more than 60dBA, indicating that the tree cover serves as a noise barrier for the park. Therefore, park planning should be tailored to its location and environment, while landscaping can be used to reduce noise levels and keep them within noise limits. In the future, the soundscape idea may be taken into account to enhance Malaysia's park environment.

A Comparative Study of Scarfed Nozzle for Jet-Installation Noise Reduction

The experimental investigation of the effects of scarfed nozzles on jet-installation noise was conducted using unheated subsonic jets in an anechoic jet noise facility. Four different types of scarfed nozzles with increasing nozzle lip angles were examined to study the installation effects at various plate distances away from the jet. Mach numbers ranging from 0.3 to 0.8 were investigated in the experiments. The use of scarfed nozzles is known to result in the deflection of flow away from the centre axis, inducing asymmetry in the jet shears, leading to azimuthal variation in the spectra, and ultimately, noise reduction. This study aims to explore the possibility of reducing jet-installation noise using scarfed nozzles at subsonic flow conditions. The characteristics of jet hydrodynamic pressure fluctuations were investigated in the axial direction using far-field measurements. The near-field flow features were studied using surface pressure transducers installed on the flat plate for the installed configurations. Detailed spectral, coherence, and correlation analyses were carried out to determine the noise reduction mechanisms associated with scarfed nozzles in the proximity of a flat plate. The results of the study showed that the use of scarfed nozzles significantly reduced the jet-installation noise. The reduction was attributed to the generation of an asymmetric flow field induced by the nozzle geometry. The reduction in noise levels was also observed to increase with increasing nozzle lip angle. The detailed analyses revealed that the noise reduction mechanism was associated with a decrease in the acoustic power generated by the jet. Overall, the results suggest that scarfed nozzles can be an effective means of reducing jet-installation noise in subsonic flow conditions.

METHODS OF IMPLEMENTING GREEN ARCHITECTURE IN THE EDUCATIONAL PROCESS

The article discusses the relevance of environmental pollution and the limited availability of natural resources, and shows the importance of studying aspects of architectural ecology in the education of architectural students. The article presents some of the techniques used by students during the course and diploma design and practical tasks of the Architectural Ecology course. Architectural movements, the main concept of which is unity with nature, emerged in the middle of the twentieth century, when environmental problems began to escalate. An interesting direction for architecture students is to master the peculiarities of creating green architecture, green roofs, living walls and vertical trusses to integrate architecture into the natural landscape with the involvement of natural components in forming, merging architecture with nature. The involvement of natural components in architectural form-making can vary depending on the volume, space, functionality, and constructive use. Examples include courtyards, roofs, building facades, balconies, terraces, galleries, loggias, separate buildings and constructions, small architectural forms, landscape theatres, etc. All of these methods of using natural elements improve the aesthetic, psychological, planning, functional, energy-efficient, and structural qualities of buildings and their grounds. They reduce noise levels, change temperature, refresh the space, have a positive effect on people, improve mood, and serve as natural insulation. The use of green technologies in construction can reduce the negative impact of human activity on the environment. Green roofs and living walls contribute to the preservation of biodiversity, improve air quality and reduce temperatures in cities. Vertical trusses open up new opportunities for efficiently growing food in urban environments, helping to reduce the distance between production and consumption, and minimizing the use of resources and chemicals. Green architecture is becoming not only a symbol of aesthetics, but also a key element of modern urban development, ensuring harmony between cities and nature. Such modern constructions and design approaches can be an important step towards creating the healthier, more environmentally friendly and liveable environment.

ANALYSIS OF THE DEGREE OF STUDY AND GLOBAL EXPERIENCE IN OPTIMIZING URBAN NOISE POLLUTION

А collection and analysis of domestic and international publications on the impact of noise pollution on the physical and emotional well-being of mega-city residents were conducted. It was found that noise pollution directly affects the quality of life and the physical and mental health of people, leading to significant economic losses through medical expenses, deaths, and a decrease in the market value of real estate located near noise sources. Moreover, it was discovered that noise negatively influences not only the physical well-being of humans but also the behavior of urban animals and birds, compelling them to adapt their mating rituals and communication methods. While these behavioral changes help animals be more audible in noisy environments, they impact the reproductive success of certain species, potentially leading to their extinction and causing an ecological catastrophe. The study identified a global trend of lagging efforts to combat urban noise and solve problems only after their existence is acknowledged. The research explored the primary internationally recognized and widely used tools for reducing noise levels in urban environments, including methods within the field of landscape architecture: functional zoning of urban areas, construction of noise reduction screens (NRS), installation of noise-absorbing road surfaces, traffic restrictions, or speed limits, and the creation of green barriers, among others. Furthermore, the article outlined the main trends in the future development of improving sound comfort in cities, such as the establishment of "quiet zones" and the creation of unique soundscapes in contemporary mega-cities. Examples include the iconic sounds of Big Ben in London or the call to prayer from the Masjid al-Haram in Mecca, which provide emotionally rich experiences. In a broader sense, acoustic comfort should not be considered solely as the absence of noise but rather as a situation where acoustic environments offer significant opportunities for human development and careful consideration of their physical and mental well-being.

Energy enhancement through noise minimization using acoustic metamaterials in a wind farm

The determinantal noise pollution from wind turbines has constricted the acceptance of wind energy, posing health and environmental concerns. Existing solutions often compromise wind turbine efficiency or wind farm output, limiting the full utilization of wind energy. To address this challenge, we propose a novel method of effectively employing acoustic metamaterials (AMMs) inside a wind farm that leverages phase cancellation for noise suppression and energy enhancement. Through a combined phase retrieval, noise propagation model, and genetic algorithm, we determine the optimal layout and structural design of these AMMs inside a wind farm to minimize noise. We present two AMM designs, full-walled and segmented, and demonstrate their effectiveness for both single-turbine and multiple-turbine layout scenarios by achieving 91% (in Pa) and 10%–68% (in Pa) noise reduction, respectively, compared to reference layouts. Furthermore, we exhibit the AMM's impact in enhancing the energy throughput of wind farms by installing an additional wind turbine in a noise-restricted area of an existing AMM-equipped wind farm while maintaining a 70% (in Pa) reduction in noise levels. This approach paves the way for constructing wind farms near urban-suburban areas, complying with landscaping and visual government policies, and securing community acceptance towards sustainable power generation systems.

Active Acoustic Metamaterial Based on Helmholtz Resonators to Absorb Broadband Low-Frequency Noise.

The aim of the present work is to design active acoustic metamaterial consisting of an array of Helmholtz resonators and fabricating them using an additive manufacturing technique in order to assist in a reduction in noise levels in aerospace applications. To this aim, initially, a passive metamaterial consisting of an array of 64 Helmholtz resonator unit cells is designed and tested to establish the effectiveness and region of performance. The selected design variable for change is identified as the resonator cavity depth through the frequency response for each parameter of the Helmholtz resonance equation and randomized to achieve a broadband frequency range of the passive metamaterial. An active model of this design (actuated by a stepper motor) is fabricated and tested. The metamaterials are tested under two acoustic set-ups: a closed system aimed at recreating the environment of a soundproof room and an open-system aimed to recreate the condition of an active liner. For the case of passive system, the metamaterial gave sound attenuation of 18 dB (for f = 150 Hz) in open system configuration and 33 dB (f = 350 Hz) in closed system configuration. The attenuation obtained for the active model was 10-15 dB over the mean line performance for the case of closed system and 15-20 dB for the case of open system. The closed system was also tested for performance at multiple cavity depths by setting two wall depths at 10 mm and three walls at 50 mm. This test yielded an attenuation of 15 dB at 180 Hz, the frequency corresponding to 50 mm cavity depth, and 10 dB at 515 Hz, corresponding to 10 mm cavity depth.

Machine-learning and CFD based optimization and comprehensive experimental study on diagonal flow fan for energy conservation and efficiency enhancement

The diagonal flow fan, known for its innovative airflow guiding technique, presents a dual advantage of heightened efficiency and reduced noise levels. Despite garnering attention in energy production systems, research on optimizing outlet guide vanes for diagonal flow fan performance remains limited. This study introduces a novel machine learning approach, utilizing Opt LHD sampling instead of traditional simulations and experiments to accumulate ample sample data. The fusion of LS-SVM and improved GA-PSO is employed for multi-objective optimization of outlet guide vanes, aiming to simultaneously enhance fan performance and reduce energy consumption. Experimental assessments reveal the optimized fan's significant improvements, including a 106 Pa increase in total pressure, a 3.6 dB reduction in noise levels, and a remarkable 16.3% enhancement in total pressure efficiency. These results highlight the robustness of the machine learning approach in optimizing diagonal flow fan exit guide vanes, effectively addressing the research gap in this area. Additionally, numerical analysis of internal flow dynamics and acoustic properties pre and post-optimization uncovers the intrinsic mechanisms influencing the overall performance of the diagonal flow fan.

An implementation and evaluation of sound activated noise display for the reduction of noise levels and enhancement of staff’s sleep and noise awareness

An implementation and evaluation of sound activated noise display for the reduction of noise levels and enhancement of staff’s sleep and noise awareness

Recent Engineering Applications for Noise Reduction in an Automotive Industry

Industrialization harms as it results in the emission of noise into the surroundings and employees. Especially noise is one of the most common causes of hearing disorders and one of the most common occupational diseases in the industry. Reducing the main noise sources has become increasingly urgent since the effect on employee health was negative. Although noise reduction is an important issue in the industry, previous research has not addressed it adequately, particularly in the automotive industry. This paper presented a detailed case study on the reduction of noise in a pilot area of an automotive assembly line. The paper aimed to improve the quality of the working environment by reducing the use of Personal Protective Equipment (PPE) and noise reduction. For this purpose, noise measure tools were used: a Svantec-type noise dosimeter and a sound level meter. In the course of studies, it was creating noise maps (before/after), in order to verify whether the proposed measures will be sufficient. Once the proposed measures have been implemented, a 14.2% reduction in noise levels helped ensure employees’ safety by reducing the need for mandatory PPE. Meanwhile, the noise reduction percentage for AGV is the highest among the five noise sources, at 20.9%. Results showed that the sound pressure levels dropped from 110 dBA to 87 dBA and reduced on average for AGV. Reducing reliance on PPE and implementing noise reduction measures enhances pilot area safety and contributes to a more ergonomic and sustainable work environment. The implementation of this case, the application of the suggested measures, and the subsequent verification approved a considerable reduction in the noise levels in the influenced pilot area, and the measures applied were assessed as highly effective with result rates.

Effect of sawtooth trailing edge serrations on the reductions of airfoil broadband noise

The present paper examines the use of modified dual-wavelength sawtooth serrations introduced at the trailing edge (TE) of a National Advisory Committee for Aeronautics (NACA) 65 (12)-10 airfoil as a passive means for the control of airfoil broadband noise. The studies are conducted for different parameters such as serration wavelengths (λ), serration amplitudes (h) as well as (hꞌ) modified amplitude to determine the best serration parameter which provides higher noise reductions. The reduction of noise level brought by the modified dual-wavelength sawtooth serrations at the TE is about 4 dB, while it is about 3.3 dB for the simple ones. It reveals that the modified sawtooth can provide a substantial reduction of self-noise alongside the interaction noise over an extensive range of frequencies which indicates the existence of strong far-field destructive interference (i.e., feedback) from low to mid-frequency ranges (i.e., 1.5 - 5 kHz). The TE serrated airfoils show lower acoustic emissions as compared to baseline although they exhibit a common behavior for all emission angles. The large noise decrease provided by the dual-wavelength sawtooth may be because of the significant reductions in the scattering intensity of sound as well as strong far-field destructive interference owing to the presence of two roots between the two successive maximum amplitude peaks.

Voice use of nurses working in the intensive care unit during the COVID-19 pandemic

ObjectiveThis study aimed to investigate the voice use of nurses working in intensive care units (ICUs) and their perception of acoustic environments. Setting and sampleThe research was conducted in four different hospitals in China during the COVID-19 pandemic. A total of 60 ICU nurses were recruited for their voice use monitoring and 100 nurses participated in the survey. Research methodologyFirstly, voice-related parameters such as voice level (SPL, dB), fundamental frequency (F0, Hz), and voicing time percentage (Dt, %) were measured using a vocal monitor. To collect data, a non-invasive accelerometer was attached to the participants' necks during their working hours. Secondly, the perception of the ICU acoustic environment was assessed using semantic differential. ResultsThe results showed that nurses spoke approximately 0.9–4 dB louder to patients and colleagues in ICUs compared to quiet rooms, and their fundamental frequency (F0) significantly increased during work. The voice levels of nurses were influenced by background noise levels, with a significant correlation coefficient of 0.44 (p < 0.01). Furthermore, the background noise levels ranged from 58.1 to 73.9 dBA, exceeding the guideline values set by the World Health Organisation (WHO). The semantic differential analysis identified ‘Stress’ and ‘Irritation’ as the two main components, indicating the prevalence of negative experiences within ICUs. Implications for clinical practiceThis study highlights the potential risk of voice disorders among ICU nurses. The findings also underscore the importance of implementing strategies to reduce noise levels in ICUs to reduce voice disorders among nurses.

Attention-enhanced conditional-diffusion-based data synthesis for data augmentation in machine fault diagnosis

Data scarcity and class imbalance are pervasive challenges in machine fault diagnosis, impeding the development and broad adaptation of accurate and reliable deep-learning-based fault detection systems. To address these issues, we propose a novel attention-enhanced conditioning-guided diffusion-based approach for synthesizing additional training data. By generating noisy motor-current signals and employing a diffusion process to reduce noise levels, we obtain synthetic data that closely resembles the statistical properties and patterns of real-world data. The quality of the synthesized samples is assessed using a four-layer, pre-trained convolutional neural network, achieving an impressive classification rate of 96.39%. This demonstrates the effectiveness of our attention-enhanced conditioned diffusion-based model in synthesizing critical features for fault detection, making it well-suited for the introduced fault detection task. To further investigate the quality of the synthesized data samples, we implement a specific training strategy that uses the generated samples as training data. The trained diffusion model generates samples per class, which are then used to train a simple four-layer convolutional neural network for fault classification. Remarkably, the model achieves an accuracy of 98.96% when evaluated with real inverter signals, indicating that the generated samples effectively capture the distribution of real data. For further evaluation, multiple scenarios are created confirming the value of the additionally synthesized samples for real-world bearing fault detection. Our approach presents a well-suited solution to the data scarcity and class imbalance problem in machine fault diagnosis. The proposed method enhances the accuracy and reliability of fault diagnosis systems, offering valuable insights for various real-world condition monitoring applications.

Application Effect of Comprehensive Noise Reduction Technology in Outpatients with Vitiligo: A Retrospective Study.

Noise is a kind of perceived public nuisance that is closely related to people's subjective feelings and lives. This study explores the clinical application effect of comprehensive noise reduction technology in outpatients with vitiligo. A total of 76 patients with vitiligo were selected in the Department of Dermatology at Baoding No. 2 Central Hospital from January 2020 to January 2021, as the control group (CG), receiving 5S management mode, and 80 patients with vitiligo from February 2021 to October 2022 were selected as the study group (SG), receiving comprehensive noise reduction technology combined with the 5S management mode for this retrospective study. The effects of different management modes on these patients were observed. SG had higher nursing quality scores in service attitude, service initiative, communication skills, environmental management and item management and overtly a lower noise level than CG (all P < 0.001). The Hamilton Anxiety Scale (HAMA) scores of the two groups at the end of treatment were significantly lower than those on admission (P < 0.05), with SG showing a lower score than CG (P < 0.001). Correlation analysis showed that noise levels and HAMA scores had a positive correlation (r = 0.423, P < 0.001). Patients with negative feelings about medical treatment caused by various noise sources in SG were obviously less than those in CG (P < 0.05). Both the groups had a statistical difference in overall satisfaction (P < 0.05). The investigation and data analysis demonstrated that comprehensive noise reduction in outpatients with vitiligo had a considerable effect. This technology can standardise the behaviour of medical staff, enhance nursing quality, reduce noise levels and alleviate patients' anxiety and improve their satisfaction. It has great benefits for the outpatient environment and patients.

Increasing the stability of the synchronization mode of the PLL system

Nowadays, the extremely rapid development of the global telecommunications network is accompanied by the search for new and the improvement of already existing radio- and other technologies, which are intended to further advance existing systems towards the construction of even more productive global transport networks, as well as networks of wireless broadband access, including 6G mobile communication networks and networks of subsequent generations. Among the important and widely used systems, it is worth highlighting the radio engineering system such as the Phase-Locked Loop (PLL) system, the capabilities for further improvement of which are far from exhausted. In particular, articles on various research issues and the use of the PLL systems for various applications are regularly published in world scientific and engineering publications. The use of PLL covers the issues of stabilizing the frequency of high-frequency generators, building high-precision frequency synthesizers and narrowband tracking filters, signal extraction against the background of noise in Doppler systems, demodulation of signals with frequency and phase modulation, the operation of magnetic recording playback devices, etc. This article analyzes the operating modes of the PLL system, in particular search, capture and hold, and it is found that when searching for the frequency of the reference generator, the system does not provide tuning of the frequency of the voltage-controlled generator as close as possible to this frequency. This, in turn, leads to the fact that after the frequency of the reference generator enters the capture range, the PLL system is instantly activated, which compensates for the current value of the frequency difference between the two generators, using part of the useful capability of the phase detector to process the frequency changes of both generators within the linear section of its discrimination characteristic. This situation is equivalent to not finding the frequencies of the reference and controlled generators, when their frequencies are equal, in the middle of the retention area, which negatively affects the stability of the PLL system as a whole. Based on the conducted analysis and the obtained conclusions, the paper proposes the principle of adjusting the PLL system as close as possible to the middle of the synchronization (holding) area, which ensures increased stability of the system against the influence of external factors, and also positively affects the reduction of the frequency noise level of this system. According to this principle of tuning, a corresponding block diagram of the PLL system was developed and an explanation of the operation of such a scheme was provided.

The problems of designing helicopters with regard to the requirements for cabin noise

High noise levels in helicopter cabins are currently an important problem in solving environmental problems in civil aviation. The published data indicate high noise levels in the cabins of operated helicopters of the order of 93-97.4 dBA, while noise levels of less than 80 dBA are safe for humans. In order to significantly reduce noise levels in helicopter cabins and ensure the required level of acoustic comfort for passengers, an integrated approach is proposed, consisting in the use of sound insulation and vibration damping materials in the on-board structure, as well as sound-absorbing structures configured to work effectively in the problematic frequency range of the helicopter passenger cabin.

Оцінка ефективності надання екосистемних послуг зі зниження рівня шуму від дорожнього руху у міських зелених зонах міста (на прикладі міста Києва)

Noise pollution is one of the most important factors in the deterioration of the quality of life in cities. Natural vegetation in urban green spaces (UGS) is an effective instrument for reducing road noise. The primary pollution field and the parameters of the UGS determine their different ability to reduce noise levels to comfortable or at least safe levels. One of the directions in the field of recreational research is to assess the effectiveness with which UGS provide noise reduction. Accordingly, the purpose of this paper is to provide such an assessment on the example of the UGS of Kyiv. In the study, the primary field of noise pollution from roads with different traffic intensities was determined. Modelling has shown that at the border of green spaces, noise values of up to 73 dB are observed in more than half of the city's UGSs. When determining the effectiveness of the noise reduction function, it was found that the majority of UGSs (75%) have a strong potential to reduce noise levels (from 0.7 to 0.8). The modelling results showed the high efficiency of green spaces in Kyiv in performing this function - 90% of the UGSs provide safe conditions for staying. Converting the efficiency values into volumes of ecosystem services (ES) based on the Harrington's desirability function allows us to understand that, given the current levels of traffic load and the parameters of UGS, the maximum volumes of noise reduction ecosystem services provided by vast majority green spaces in Kyiv (2982 objects).

Accelerated multiple-quantum-filtered sodium magnetic resonance imaging using compressed sensing at 7 T

PurposeMultiple-quantum-filtered (MQF) sodium magnetic resonance imaging (MRI), such as enhanced single-quantum and triple-quantum-filtered imaging of 23Na (eSISTINA), enables images to be weighted towards restricted sodium, a promising biomarker in clinical practice, but often suffers from clinically infeasible acquisition times and low image quality. This study aims to mitigate the above limitation by implementing a novel eSISTINA sequence at 7 T with the application of compressed sensing (CS) to accelerate eSISTINA acquisitions without a noticeable loss of information. MethodsA novel eSISTINA sequence with a 3D spiral-based sampling scheme was implemented at 7 T for the application of CS. Fully sampled datasets were obtained from one phantom and ten healthy subjects, and were then retrospectively undersampled by various undersampling factors. CS undersampled reconstructions were compared to fully sampled and undersampled nonuniform fast Fourier transform (NUFFT) reconstructions. Reconstruction performance was evaluated based on structural similarity (SSIM), signal-to-noise ratio (SNR), weightings towards total and compartmental sodium, and in vivo quantitative estimates. ResultsCS-based phantom and in vivo images have less noise and better structural delineation while maintaining the weightings towards total, non-restricted (predominantly extracellular), and restricted (primarily intracellular) sodium. CS generally outperforms NUFFT with a higher SNR and a better SSIM, except for the SSIM in TQ brain images, which is likely due to substantial noise contamination. CS enables in vivo quantitative estimates with <15% errors at an undersampling factor of up to two. ConclusionsSuccessful implementation of an eSISTINA sequence with an incoherent sampling scheme at 7 T was demonstrated. CS can accelerate eSISTINA by up to twofold at 7 T with reduced noise levels compared to NUFFT, while maintaining major structural information, reasonable weightings towards total and compartmental sodium, and relatively reliable in vivo quantification. The associated reduction in acquisition time has the potential to facilitate the clinical applicability of MQF sodium MRI.

Adaptive Unsupervised Learning-Based 3D Spatiotemporal Filter for Event-Driven Cameras.

In the evolving landscape of robotics and visual navigation, event cameras have gained important traction, notably for their exceptional dynamic range, efficient power consumption, and low latency. Despite these advantages, conventional processing methods oversimplify the data into 2 dimensions, neglecting critical temporal information. To overcome this limitation, we propose a novel method that treats events as 3D time-discrete signals. Drawing inspiration from the intricate biological filtering systems inherent to the human visual apparatus, we have developed a 3D spatiotemporal filter based on unsupervised machine learning algorithm. This filter effectively reduces noise levels and performs data size reduction, with its parameters being dynamically adjusted based on population activity. This ensures adaptability and precision under various conditions, like changes in motion velocity and ambient lighting. In our novel validation approach, we first identify the noise type and determine its power spectral density in the event stream. We then apply a one-dimensional discrete fast Fourier transform to assess the filtered event data within the frequency domain, ensuring that the targeted noise frequencies are adequately reduced. Our research also delved into the impact of indoor lighting on event stream noise. Remarkably, our method led to a 37% decrease in the data point cloud, improving data quality in diverse outdoor settings.