Noise Analysis Research Articles

Theory of quasi-ballistic FET: steady-state regimeand low-frequency noise.

Abstract We present the theoretical analysis of steady state regimes and lowfrequency
noises in quasi-ballistic FETs. The noise analysis is based on the Langevin
approach, which accounts for the microscopic sources of fluctuations originated from
intrachannel electron scattering. The general formulas for local fluctuations of the
carrier concentration, velocity and electrostatic potential as well, as their distributions
along the channel are found as functions of applied voltage/current. Two circuit
regimes with stabilized current and stabilized voltage are considered. The noise
intensities for the devices with different electron ballisticity in the channel are
compared.
We suggest that the presented analysis makes better comprehension of physics of
electron transport and fluctuations in quasi-ballistic FETs, improves their theoretical
description and can be useful for device simulation and design.

Sensitivity analysis of an inverted T-shaped vertical tunneling field effect transistor biosensor based on inserted finger type

This paper presents a biosensor based on a finger-inserted inverted T-shaped vertical tunneling field effect transistor (FP-T-TFET). In order to improve the sensitivity and performance of the biosensor, a finger-inserted contact between the source and the channel is used. A comparative analysis between the biosensor based on FP-T-TFET and conventional inverted T-shaped TFET (T-TFET) is simulated for the electrical properties and sensitivity of neutral biomolecules with different dielectric constants and charged biomolecules with different charge densities. The noise analysis of the proposed structure is also performed. Then, the effects of insertion finger distribution, cavity size and filling volume on the performance of FP-T-TFET are investigated. Finally, the structure was subjected to linear analysis, in which the pearson coefficient was 0.92, indicating that the structure has good linear correlation. The results show that the FP-T-TFET biosensor has higher sensitivity in detecting various neutral and charged biomolecules. All device simulations were performed in the TCAD environment with a well-calibrated structure.

Analysis and optimization of abnormal noise in lubricating oil circuit of diesel engine

Engine abnormal noise is one of the common engine faults, which will affect the comfort, power and safety of the automobile at the same time. In order to study the abnormal noise existing in the test process of diesel engine lubricating oil circuit system, 1D numerical simulation analysis of its flow field is carried out by using simulation software GT-power to verify the boundary conditions of the model and analyze the fluctuation of pressure at different speeds and temperatures. Through numerical analysis, it is found that there is almost no pressure fluctuation in the lubrication system before the pressure limiting valve is opened, but after the pressure limiting valve is opened, pressure fluctuation occurs in the pipeline, and the pressure fluctuation is different at different positions. Finally, the lubrication pipeline is simulated and analyzed by Pumplinx software, and the pressure fluctuation in the lubrication pipeline of diesel engine is reduced by optimizing the diameter of the oil pipeline and increasing the cavity structure.

UltraStat: Ultrafast Spectroscopy beyond the Fourier Limit Using Bayesian Inference.

The discrete Fourier transform (dFT) plays a central role in many ultrafast experiments, allowing the recovery of spectroscopic observables from time-domain measurements. In resonant experiments when population relaxation and coherence components of the signal coexist, the dFT is usually preceded by multiexponential fitting to remove the large population term. However, this procedure results in errors in both the recovered decay rates and the line shapes of the coherence spectral components. While other methods such as linear prediction singular value decomposition fit both terms simultaneously, they are limited to specific models that may not represent the true signal. These methods do not allow for systematic noise analysis or error estimation and require a priori knowledge of the signal rank. Here, we describe a general approach to parameter estimation in ultrafast spectroscopy─UltraStat─grounded in Bayesian analysis without the limitations set by Fourier theory. Using simulated, but realistic data, we demonstrate in a statistical sense how UltraStat provides accurate parameter estimation in the presence of many experimental constraints: noise, signal truncation, limited photon budget, and nonuniform sampling. UltraStat provides superior resolution compared to the dFT, up to an order of magnitude in cases where the line shapes are well-approximated. In these cases, we establish that primarily noise, not sampling, limits spectral resolution. Moreover, we show that subsampling may reduce the number of acquired points by 90% compared to the Nyquist-Shannon criteria. UltraStat greatly improves parameter estimation by providing statistically bound spectral and dynamics analysis, pushing the limits of ultrafast science.

Line-scan phase-resolved synthetic wavelength LiDAR using an off-axis holographic approach.

We demonstrate a novel, to our knowledge, approach for phase-resolved coherent 3D surface imaging that utilizes synthetic wavelength phase-based ranging and line-scan off-axis holography. Our proof-of-concept system employs an akinetic tunable laser to perform fast wavelength switching and a galvanometer mirror for slow-axis mechanical scanning. Quantitative depth measurements of an anodized aluminum plate and 3D-printed depth calibration targets and a printed circuit board are demonstrated. Analyses of both shot-noise limited system performance and speckle noise are also presented. The proof-of-concept system achieves micron-scale depth precision with a FOV of 12.8 mm × 34 mm and a 50 ms image acquisition time.

Inducing pitting in low carbon steel via chloride contamination: Electrochemical noise analysis in concrete gel pore solutions

This study explores an alternative approach to examining the corrosion of reinforced concrete, a persistent and challenging issue. The research utilizes an agar-based gel as a synthetic pore solution to simulate the environment of reinforcing steel, with the goal of confining pitting corrosion induced by chlorides to specific areas of the steel. By employing this innovative approach, metastable and stable pits were successfully induced according to the Cl−OH− ratio at pre-selected locations on the steel surface. The presence of metastable pits was determined in the range of 31.6 >Cl−OH− > 3.2, as indicated by electrochemical noise analysis. The findings support the efficacy of this experimental procedure for enabling precise manipulation and contamination of localized regions with chloride ions.

Noise analysis of a quasi-phase-matched quantum frequency converter and higher-order counter-propagating SPDC

Noise analysis of a quasi-phase-matched quantum frequency converter and higher-order counter-propagating SPDC

Study on the aerodynamic performance and noise of windshield area in high-speed trains at a frequency of 38 hz

The noise level of a high-speed train is a crucial indicator of its operational quality. A significant low-frequency interior noise, referred to as ‘38 Hz’ in this context, has been detected during the operation of high-speed trains. This notable noise primarily occurs in the train attendant’s cabin near the windshield area. In this study, we conducted a comprehensive full-scale test to investigate the preliminary cause behind this significant ‘38 Hz’ noise. Our investigation reveals that it is associated with aerodynamic noise originating from the windshield area. To identify the root cause of this ‘38 Hz’ noise in the windshield area, we established a computational fluid dynamics (CFD) based model for aerodynamic noise analysis. The causes were found to be related to both the size and opening of the windshield cavity. Simulation results demonstrate that closing the upper opening significantly reduces the volume of ‘38 Hz’ noise compared to the original outer windshield structure design. We verified and validated these findings through an extensive full-scale test, which showed that by implementing our proposed modified windshield structure, there was approximately 7 dB reduction in significant ‘38 Hz’ noise observed within the train attendant’s cabin near the windshield area.

Analysis and measurement of magnetic noise for tesla shielding based on superconducting coils applied to SERF magnetometer

Tesla Shielding (TS) is closed superconducting coils composed of superconducting tape, designed to resist changing magnetic fields, thereby achieving magnetic shielding. TS, optically transparent, is suitable for integration with spin exchange relaxation-Free (SERF) magnetometers, thereby improving the sensitivity of SERF magnetometers. However, no prior research has been conducted on the magnetic noise of TS. Noise source identification was conducted on the superconducting tapes used in the TS. We modeled the magnetic noise of superconducting coils, analyzed the the relationship between geometric parameters and magnetic noise of coils, and proposed methods to suppress magnetic noise. Finally, we established a measurement system to measure the magnetic noise of superconducting coils. The results confirm the feasibility of the magnetic noise calculation model and the effectiveness of the methods for suppressing magnetic noise. This study can guide the design of TS, which is important for improving the sensitivity of SERF magnetometers.

Population-Level Exposure to PM2.5, NO2, Greenness (NDVI), Accessible Greenspace, Road Noise, and Rail Noise in England

Air pollution, greenspace and noise are interrelated environmental factors with the potential to influence human health outcomes. Research has measured these exposures in diverse ways across the globe, but no study has yet performed a country-wide analysis of air pollution, greenspace, and noise in England. This study examined cross-sectional PM2.5, NO2, greenness, accessible greenspace, road noise, and rail noise exposure data at all residential postcodes in England (n = 1,227,681). Restricted cubic spline models were fitted between each environmental exposure and a measure of socioeconomic status, the Index of Multiple Deprivation (IMD) rank. Population-weighted exposures by IMD deciles, urbanicity, and region were subsequently estimated. Restricted cubic spline models were also fitted between greenness and each other environmental exposure in the study. The results show some evidence of inequalities in exposure to air pollutants, greenspace, and noise across England. Notably, there is a socioeconomic gradient in greenness, NO2, PM2.5, and road noise in London. In addition, NO2, PM2.5, and road noise exposure decrease as greenness increases in urban areas. Concerningly, almost all air pollution estimates in our study exceed international health guidelines. Further research is needed to elucidate the socioeconomic patterns and health impacts of air pollution, greenspace, and noise over time.

Analysis and suppression research of high lift device noise based on large aeroacoustic wind tunnel test

The exterior noise of large aircrafts is an important aspect for the airworthiness certification. The high-lift device is one of the key noise sources for large aircrafts, thus the analysis and reduction of high-lift device noise is important and meaningful. Based on the 5.5m×4.0m Aeroacoustic Wind Tunnel and a half model for the aeroacoustic study of large scale aircrafts, the high-lift device noise properties were studied experimentally. First, the experimental platform, the test model, the test system and noise reduction design were introduced. Then, based on the experimental results, the noise characteristics of the high-lift devices were analyzed. The effects on the noise from the angle of attack and the wind speed were compared. The effects on the high-lift device noise from the noise reduction design on slat and flap were investigated. The results show that, the high-lift device noise has a broad frequency spectrum, with some peak frequency components. As the angle of attack is increased, the noise of the model is generally increased in the medium to high frequency range. With the wind speed increased, the noise is increased dramatically, and the frequency spectra keep a good similarity. The peak noise is suppressed by the noise reduction design.

Sensitivity analysis of landing and takeoff noise for conceptual low-boom supersonic aircraft using variable noise reduction system

This paper presents the results of an analysis of the sensitivity of the use of a variable noise reduction system (VNRS), considered in the new landing and takeoff (LTO) noise standard for supersonic aircraft, using a Japan Aerospace Exploration Agency (JAXA)-designed 66-ton twin-engine conceptual low-boom supersonic airliner as an example. The analysis was conducted using a tool developed by JAXA and examined the sensitivity of low-speed aerodynamic performance, the sensitivity of takeoff reference speed, the sensitivity of thrust control and flap control duration time ranges, and the sensitivity of noise level to takeoff profile uncertainty. The analyses showed that improving low-speed aerodynamic performance and increasing the takeoff reference speed significantly impact noise levels and the use of VNRS could reduce noise by 2.1 EPNLdB while maintaining the performance of the aircraft. Because the effective noise reduction method by changing the takeoff procedure considered differs for each noise measurement point, it is important to design a takeoff procedure that incorporates an appropriate VNRS. Uncertainty of the takeoff profile was also investigated using Monte Carlo simulations, and it was shown that noise reduction by VNRS is effective even with the assumed uncertainty in the takeoff profile.

Comparative analysis of the heavy-weight floor impact noises using different types of EVA resilient materials

The present study aims to improve the floor impact noises using various shapes of EVA resilient materials in composite floor structures. In order to this, three different types of EVA resilient materials were used including flat plate, deck plate type and cavity type of EVA boards. All the composite structure consisted of PP panel, PET and EVA resilient materials with a total depth from 30mm to 40mm. Total of 9 specimens were made for floor impact sound measurements. All the floor impact sound measurements were done at the recognized testing authority using bang machine. The values of L'I,Fmax,AW were deduced from every measurements. As a result, among the various types EVA resilient materials, most high performances were drawn when cavity type of EVA resilient material was used. It was shown that the average L'I,Fmax,AW value of cavity type was 46dB while 47dB for deck plate type, 48dB for flat plate were measured in average. It can be recognized that the good performance of cavity type EVA materials is caused by the both air layer gap beneath EVA board and air cavity inside the EVA board as well as the low dynamic elastic modulus of EVA.

Higher-fidelity analysis of air source heat pump noise via scanning intensity measurement

The need to shift to reduce carbon emissions to hit Net Zero is currently driving plans for large scale rollouts of Air Source Heat Pumps (ASHPs), due to their increased thermal efficiency and lack of direct carbon emissions. Concern exists, however, over the potential environmental noise impact that these units could generate. The noise generated by ASHPs is measured according to BS EN 12102-2:2019. This allows a choice of several laboratory test procedures for the acoustic part, but in each of these methods only overall sound power is measured. Such measurements are crucial, but they cannot give insight into the directivity of the noise from the unit - as is required for accurate acoustic propagation modelling - and they cannot give diagnostic information that would aid improvements to designs, e.g., by showing which parts of an ASHP radiate the most noise. This paper explores the benefits offered by scanning intensity measurement, here using a Microflown Scan and Paint 3D system. This can provide a map of active and reactive intensity around the unit - in addition to pressure and particle velocity - allowing noise from components and directivity to be estimated. Advantages and challenges are discussed.

Case-study analysis of traffic noise at Vesterbrogade, Aarhus, Denmark

This paper analyses the livability, concerning traffic noise, in apartment buildings along one of the most heavily trafficked streets in Aarhus, Denmark. The case-study site is analyzed with noise prediction models and different improvements on the sound environment are proposed through qualitative aspects. The analyses are conducted using two different noise prediction models, opeNoise in QGIS and SoundPLAN. OpeNoise uses the noise prediction method CNOSSOS and SoundPLAN uses Nord2000. Noise maps 1,5 m above the terrain and facade noise levels are calculated. The results show noise levels on the facade far above WHO's limit, of . The noise pollution in the open space next to the roads also shows noise levels far above the recommendations, while the inner courtyard shows acceptable noise levels. Several subjective improvements of the sound environment are proposed, such as vegetation between the road and the building. Furthermore, different designs were proposed to reduce the amount of noise-polluted facades. This research work emphasizes the importance of considering qualitative parameters simultaneously with the noise prediction models.

Nanoscale organization of cardiac calcium channels is dependent on thyroid hormone status.

Thyroid hormone dysfunction is frequently observed in patients with chronic illnesses including heart failure which increases risk of adverse events. This study examined effects of thyroid hormones (TH) on cardiac T-tubule (TT) integrity, Ca2+ sparks, and nanoscale organization of ion channels in excitation-contraction (EC)-coupling, including L-type calcium channel (Cav1.2), ryanodine receptor-type 2 (RyR2), and junctophilin-2 (Jph2). TH deficiency was established in adult female rats by propyl-thiouracil (PTU) ingestion for 8 weeks; followed by randomization to continued PTU without or with oral triiodo-L-thyronine (T3; 10 ug/kg/d) for two additional weeks (PTU+T3). Confocal microscopy of isolated cardiomyocytes (CM) showed significant misalignment of TTs, and increased Ca2+ sparks in thyroid-deficient CMs. Density-Based Spatial Clustering of Applications with Noise (DBSCAN) analysis of STochastic Optical Reconstruction Microscopy (STORM) images showed decreased (p<0.0001) RyR2 cluster number per cell area in PTU CMs compared to euthyroid (EU) control myocytes, and this was normalized by T3-treatment. Cav1.2 channels and Jph2 localized within 210 nm radius of the RyR2 clusters were significantly reduced in PTU myocytes, and these values were increased with T3 treatment. A significant percentage of the RyR2 clusters in the PTU myocytes had neither Cav1.2 or Jph2, suggesting fewer functional clusters in EC-coupling. Nearest neighbor distances between RyR2 clusters were greater (p<0.001) in PTU cells compared to EU and T3-treated CMs that corresponds to disarray of TTs at the sarcomere z-discs. These results support a regulatory role of T3 in the nanoscale organization of RyR2 clusters and co-localization of Cav1.2 and Jph2 in optimizing EC-coupling.

The method to determination of the utilization of thrust reversers after landing based on noise measurements and analysis of its results

The use of powerful thrust reversers after landing often results in a noise impact on the area of surrounding the airport. The use of thrust reversers, while not necessarily a prerequisite for landing maneuvers, is sometimes a significant means of ensuring more safety for the pilot. For this reason, the magnitude of the thrust reversers, and the segment of the runway in which the reversers are used, vary widely. We have established a method to determination of the utilization and the strength of reverse thrust from noise measurements taken at several stations along the runway side. This report also describes an analysis of the results of the operational conditions of thrust reversers at a multitude of Japanese airports that were examined using the methodology.

Enhancing vibroacoustic reduced order models for digital twin development in industrial applications

In recent years, the growing interest towards the Digital Twin has prompted extensive exploration in both academic and industrial domains. To realize this technology, the development of simulation models that seamlessly run parallel to the physical assets is necessary. Model Order Reduction (MOR) plays a pivotal role, significantly easing the computational demands of 3D models while maintaining high fidelity. Krylov-based methods have proven successful in various vibroacoustic applications. However, state-of-the-art contributions employ suboptimal modeling strategies, leading to computationally inefficient offline phases and limited scalability. The linear Finite Element Method (FEM) exhibits lower efficiency than high-order FEM; Astley-Leis infinite elements, used to enforce non-reflecting conditions, constrain models to spherical domains, proving inefficient for elongated structures. In this work, advanced techniques-FEM Adaptive Order (FEMAO) and flexible infinite elements- are employed to alleviate the computational burden of the MOR process. The advantages of combining MOR, FEMAO, and flexible infinite elements are explored through various numerical examples. Specifically, we highlight the efficiency of output-based MOR in handling models with a high number of inputs, showcasing practical applications, especially in electric motor noise analysis. In conclusion, these numerical techniques reduce the computational burden of the offline phase, unlocking the Digital Twin for large-scale industrial models.

Development of integrated noise analysis systems for ship propellers considering hull wake

Recently, the requirements for underwater radiated noise (URN) reductions in ships have become significant issues, driven by concerns over the impact of naval vessel performance and noise on marine ecosystems. The majority of URN generated from ships is attributed to the propeller. This study developed the integrated noise analysis systems that predict and analyze all the significant noises generated from the propellers, considering the hull wake. Since each type of noise has different sources and mechanisms, it is essential to analyze all types of noise to evaluate the propeller noise performances comprehensively. The model was developed for cavitation noise by compression and expansion motion of bubbles to evaluate the radiated noise. For non-cavitation noise, a noise model on the frequency domain was derived to cover the noise generated by changes in the wake. The unsteady pressure on the rotating blade was obtained using flow fields and wall pressure spectrum, extending to high frequencies. The developed system provides a valuable tool for propeller optimization designs by minimizing URN while considering the shape of the hull and appendages.

Comparative analysis of CNN and TNN models in environmental noise source identification

This paper presents a focused examination of environmental noise, an issue of relevance due to its implications for human health and well-being, compliant with ISO 1996-2:2017 standards. Moving beyond the traditional methodologies that primarily rely on level exceedance, our study integrates advanced machine learning techniques to address the challenges in noise source identification. With the advent of IoT Noise Monitoring Terminals, the conventional manual auditory analysis methods have become less feasible. Our research explores the application of convolutional neural networks (CNNs), a standard in environmental noise analysis, and assesses the emerging utility of Transformer Neural Network (TNN) models in this domain. The aim is to conduct an objective comparison of these models, applying them to identical datasets to determine their effectiveness in identifying noise sources. Through this analysis, the study seeks to contribute to the field of environmental acoustics by offering insights into the comparative strengths and limitations of CNN and TNN models.