Analysis Of Noise Characteristics Research Articles

Analysis of noise characteristics of metal processing equipment

The management and prevention of industrial injuries among workers are crucial in the work environment. Industrial injuries occur in various forms and have diverse causes, and noise-induced hearing loss accounts for a significant proportion of workplace injuries. Therefore, this study aimed to measure the factory noise during engine-component (metal) processing for automobiles, where substantial noise-induced hearing loss is prevalent. The measurement results revealed that the 24-h equivalent continuous noise level (Leq) was approximately 83.8 dB(A), and the noise at two points was higher than the noise exposure standard of 89 dB(A). These points were identified as locations where 2,200- to 3,500-ton casting machines were positioned on both sides to melt iron to produce components. The noise generated from each machine is assumed to have combined at these points, resulting in elevated noise levels. The results were plotted on a noise rating (NR) curve. The NR values ranged from 81 to 83, surpassing the standard NR range of 60 to 70 that is commonly used in typical workplaces. The frequency band that determined the NR was 2 kHz. Therefore, measures such as the use of porous sound-absorbing materials should be considered to attenuate the frequency range based on the noise characteristics.

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.

Analysis of Channel Current Noise in Small Nanoscale Metal Oxide Semiconductor Field Effect Transistors.

The shrinkage of metal oxide semiconductor field effect transistor (MOSFET) to the small size of the nanoscale results in changes in their channel current noise composition. This paper determines the channel current noise composition of 90nm MOSFET through experiments, and according to the device material and noise characteristics analysis, the channel current noise of 90nm and below is obtained, which not only contains thermal noise and suppressed channel shot noise, but also adds suppressed gate tunneling shot noise and cross-correlation noise. Then, Monte Carlo simulation of 10nm MOSFET noise is further used to determine the channel current composition of small size nanoscale devices. Subsequently, based on the device structure and fundamental characteristics of channel current noise, the channel current noise model is established. Finally, this model is employed to analyze the relationship between thermal noise, suppressed shot noise, cross-correlation noise, and channel current noise in relation to bias parameters and device characteristics. The theoretical results are basically consistent with the experimental and the simulated results, and the channel noise increases with the increase of bias voltage. This achievement holds promise for enhancing the operational efficiency, reliability, and lifetime of nanoscale small-sized MOSFET devices.

Electromagnetic noise characteristics analysis and noise traceability in induction motor

Abstract To investigate the electromagnetic vibration and noise issues in induction motors, this study employs a combined methodology of experimental, theoretical, and simulation approaches to analyze the characteristics of electromagnetic noise. Initially, a theoretical analysis of the radial electromagnetic force of the motor is conducted, followed by a simulation of the motor’s electromagnetic vibration and noise at a working condition of 3000 rpm, incorporating a Multiphysics coupled analysis of electromagnetic-vibration-noise. Vibration testing on a specific compressor motor reveals that the primary vibration noise characteristic frequency is centered around 2000 Hz. A comparison between simulation and experimental results shows a high degree of congruence, indicating the reliability of the simulation method. Subsequently, an acoustic camera kit, Brüel & Kjær PULSE Reflex, based on a beamforming method, is employed for noise source identification and acoustic holography testing at 3000 rpm, which successfully localizes the noise sources. The analysis and experiments provided herein can serve as a reference for the development of electromagnetic vibration noise suppression techniques in induction motors.

Noise characteristics analysis and suppression of optical system based on infrared superconducting single-photon detector

Superconducting nanowire single-photon detector is a kind of refrigerated photon-counting detector with high performance, which can detect extremely weak signals. The noise of optical system is an important factor limiting the sensitivity of infrared superconducting nanowire single-photon detector. In order to improve the sensitivity of infrared detection system, the calculation model of signal-to-noise ratio and background radiation of infrared optical system based on superconducting single photon detector is established and the source of noise in optical system and the radiation emission of black body are analyzed theoretically. The noise characteristics of infrared optical system are quantitatively analyzed by photon counting capability of superconducting nanowire single-photon detector, and the relationship between the photon count rate and temperature under a small temperature difference is explored. An optical system based on infrared superconducting single photon detector is designed. The designed optical system improves the infrared photon coupling efficiency and the signal-to-noise ratio of the superconducting detection system, which are verified theoretically and experimentally , thus reducing the influence of background radiation on the detection system. The results show that the superconducting single-photon detector has high sensitivity to the analysis of the infrared optical system, and the minimum resolved movement distance is 2.74 × 10<sup>–2</sup> mm. The physical coupling efficiency of the optical system and the photon count rate of the detection system are improved by optimizing the optical system, and the signal-to-noise ratio of the system increases by 2.7 times under the same conditions. It is expected that this infrared superconducting nanowire single-photon detector can be used in finer and higher precision detection field.

Flow-Induced Noise Characteristics Analysis of a Pipeline Structure in a Cabin Rigid Corner

The acoustic radiation characteristics of pipeline structures caused by turbulent fluctuating pressure are among the most important acoustic radiation sources in vessel cabins. Studying the vibro-acoustic characteristics of pipeline structures is of great relevance to engineering. The turbulence fluctuation pressure of pipeline structures’ inner surfaces was numerically analyzed by using the large eddy simulation (LES) method. At first, the vibro-acoustic differential equation of the pipeline structure system was derived by defining the fluctuation pressure as the excitation loading. According to the acoustic radiation characteristic in the quarter-infinite space, which had a combination of two rigid wall interfaces at the same time for the pipeline structures in the vessel cabins, the double reflection method, mirror image method and elastic wave Graf addition principle were applied, and the analytical function of the acoustic radiation for the cylindrical shell was derived. For the pipeline structures in the quarter-infinite acoustic space, for example, the numerical calculation for the acoustic radiation of cylindrical shell was carried out, which was excited by the turbulent pulsating pressure. Finally, the influence of inner flow velocity, frequency, and pipeline installation position were compared using numerical analysis. The results can provide technical support for the acoustic design of pipeline structure systems with complex acoustic boundaries.

Mobility Enhancement Induced by Oxygen Gettering of TiAl for Metal Gated NMOSFETs

In this work, the influence of TiAl gate electrodes fabricated by physical vapor deposition (PVD) and atomic layer deposition (ALD) on electron mobility for metal-gated NMOSFETs is respectively investigated. Due to the specific production chemistry, the ALD TiAl film inherently contains lots of C atoms, which further suppresses its O-gettering capability. Compared to the ALD TiAl device, about 15% higher peak mobility for the PVD TiAl device is demonstrated, which is attributed to the lower bulk trap density in gate dielectric layers as revealed by the 1/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}$ </tex-math></inline-formula> noise characteristics analysis. By means of the energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) analysis, the reduced trap density is related to the fact that PVD TiAl can extract more O atoms from gate dielectric layers than ALD TiAl, which weakens the electron trapping/de-trapping process and correspondingly enhances the mobility.

Applying a proven filtering method to adjust the training sample of neural networks

The article notes the complexity and duration of the process of forming a training sample of a neural network, since the correctness of the sample is checked by assessing the quality of the network after its training, it also notes the negative impact of the commonly used formal method of forming a training sample of a neural network without taking into account the physical processes of data and signal transformation in real devices on the quality of the network when filtering the noise of the speech signal. Methods and means for filtering the noise of speech signals are described. To solve the filtering problem, a sequence of main stages of processing a speech signal containing noise is presented, and their description is given. The article proposes to choose a filtering method based on the analysis of noise characteristics, while it is recommended to distinguish between homogeneous (monotonic) and dynamically changing (random) noise, for which filtering methods are different. When choosing a filtering method, it is proposed to take into account the degree of correspondence between the frequency range of the noise and the speech signal. As the main way to reduce noise, an approach is proposed based on the use of an improved and proven method for filtering noise by subtracting the spectral components of noise from the spectrum of a signal containing noise. This approach is proposed to be used for the formation and correction of a training set for a neural network designed to reduce noise in a speech signal. The results of the practical application of the proven filtration method confirmed the feasibility of its application. An important result of the work presented in the article is the possibility of evaluating the feasibility of specific corrective changes in the neural network training set by comparing it with the filtering results of the modified and tested method.

Analysis of Noise Characteristics in Partial Discharge Diagnosis for Gas Insulated Load Break Switches

Analysis of Noise Characteristics in Partial Discharge Diagnosis for Gas Insulated Load Break Switches

Fluorescence image noise characteristic analysis of flow field parameter measurement based on photo-dissociation hydroxyl

Owing to its easy generation, high-temperature resistance, and ubiquity, OHp has become the preferred fluorescent tagging molecule for flow field parameter measurement. Thus, an accurate analysis of an OHp fluorescence image provides basic data for inversion of abundant flow field parameters and complex flow field analysis. In this study, a noise characteristic analysis method was developed based on the statistical analysis of OHp fluorescence images for flow field parameter measurement. Based on a statistical analysis of the background noise of the experimental OHp fluorescence images in flow field parameter measurement, the statistical distribution of noise is revealed using the Burr XII distribution. This noise-fitting distribution has a relative mean square deviation of less than 2.5%, and it lays the foundation for removing background noise and accurately inverting similar flow field parameters.

Analysis of the characteristics of noise from substations in buildings

The urbanization has resulted in an increasing number of transformer stations, which has resulted insignificant building noise problems. However, noise problems persist because of inadequate noise characterization and the use of imperfect noise evaluation indexes for centralized substations. Based on this problem, a transformer vibration noise coupling analysis method based on empirical mode decomposition (EMD) and spectrum analysis is proposed in this study. The proposed method accurately and effectively screens and characterizes transformer noise and provides a theoretical basis for transformer noise reduction. To verify the effectiveness of the proposed method, a transformer was reconstructed as an example. It was found that the low-frequency noise from the transformer was mainly caused by vibrations with a frequency below 500 Hz, particularly frequencies of 300 Hz and 100 Hz and 50 Hz. Through the calculation and analysis of eigenvalues, the noise reduction measures focusing on vibration reduction were proposed. In the end, a noise reduction of 10 dB was achieved, which meets the comfort requirements. This method can accurately and effectively identify the characteristics of transformer noise, which makes up for the insufficiency of transformer characteristics analysis in the past. Provide guidance for perfecting transformer noise evaluation index. Practical implication: The noise problem caused by substations is getting more and more serious. Conventional noise detection and noise reduction methods can no longer meet people’s requirements for sound comfort. The coupling analysis method of vibration and noise based on EMD and spectrum analysis proposed in this study can effectively extract the characteristics of transformer noise. It provides theoretical support for the noise reduction transformation of transformers, and solves the problem that the current engineering noise reduction transformation has no theoretical basis. Noise characteristic analysis can make up for the shortcomings of existing acoustic comfort indicators that only use sound pressure level as the evaluation indicator.

Analysis of Denoising Methods of Underwater Acoustic Pulse Signal Based on Wavelet and Wavelet Packet

Underwater acoustic countermeasures include active sonar countermeasures and passive sonar countermeasures. In order to achieve the best operational efficiency of jamming equipment, the generation of jamming signals must adapt to the development trend of underwater acoustic detection technology-nonlinear time-varying and broadband characteristics. Feature extraction is to map the high-dimensional original data to the low-dimensional transformation space through a certain mapping relationship, which can suppress a large amount of redundant information in the data and highlight the category information of the data. One of the applications of wavelet analysis in signal analysis and processing is to remove noise components from signals. In practical engineering applications, sampled signals are inevitably polluted by various noises and interferences. Through the analysis of noise characteristics, it can be seen that the wavelet denoising method is very effective in removing signal noise. In this paper, aiming at the signals with different spectrum distribution, we use various methods to de-noise in order to find the de-noising methods suitable for underwater acoustic pulse signals with different frequency characteristics, and thus find an effective means to detect signals.

Noise characteristic analysis and sound sources identification for rod–airfoil interaction using different subgrid-scale models

Four subgrid-scale models based on large eddy simulation (LES), such as Smagorinsky–Lilly (SL), dynamic Smagorinsky–Lilly (DSL), wall-adapting local eddy-viscosity (WALE), and dynamic kinetic-energy transport (KET) were used and couple Ffowcs Williams–Hawkings equation to accurately analyze and identify the characteristics and position of the sound sources of rod–airfoil interaction. The results of four models were compared with experimental data. It was found that the DSL model was the optimal subgrid-scale model for the study of the interaction noise considering the calculation accuracy. Therefore, the DSL model was selected for analyzing and identifying the characteristics and location of the interaction noise source. During the calculation, solid and permeable data surfaces were used for acoustic integral surfaces. The results show that the impact of the quadrupole source is negligible at a low Mach number, and the dipole noise coming from the pressure fluctuations is dominant. Meanwhile, the dipole noise from the airfoil is louder than that from the rod; the leading edge of about 30% chord length of airfoil the is the main sound source of interference effect. Above results can provide guidance for research of blade-vortex interaction noise.

Experimental Analysis of Noise Characteristics of Electric Agricultural Utility Terrain Vehicle Gearbox

Noise and vibration measurement tests have been performed to analyze the source of noise in a utility terrain vehicle (UTV) gearbox to improve its quality. For accurate analysis of gearbox noise source, the effects of other test equipment should be separated from the gearbox noise results. In this study, the noise source of the gearbox was investigated through noise and vibration tests of the gearbox and dynamometer. Noise and vibration were measured during gearbox and dynamometer run-up tests. Dominant noise types were identified through order tracking analysis of the test results. Some types of noise were identified in the Campbell diagram. By separating the effect of the inverter and dynamometer noise, it was confirmed that the 6.39th-, 12.78th-, 14th-, and 28th-order components were the sources of noise generated by the gearbox. Dominant order components caused by the gearbox were identified. These components are expected to be used as excitation sources for the optimization of noise reduction in electric UTV gearboxes.

External noise characteristics analysis of straddle-type monorail transit based on field tests

Compared with the traditional urban rail transit system, the running mechanism, line laying structure and operating environment condition of straddle-type monorail transit are unique. Therefore, external noise radiated by the train has its own characteristics when the train is running. In order to improve the acoustic quality and explore the methods of noise reduction, it is necessary to carry out field test and understand its radiation characteristics. In this study, typical running lines of straddle-type monorail transit are selected for multi-state and multi-site field tests of external noise of the running train. The test conditions include straight line running state, curve line running state, slope line running state, entry and exit station state. The obtained time data are post-processed in timefrequency domain, and then the radiation characteristics of external noise are analyzed in detail. The time domain characteristic is mainly discussed based on the overall level of external noise of the running train. In frequency domain, the contributions of the sound pressure energy (CSPE) of 1/3 octave bands under each running state of the train are analyzed, and the effects of straddle-type monorail traffic noise and urban road noise on urban transportation noise are evaluated using energy contribution analysis method. Finally, the main noise sources are briefly identified and analyzed. The research results will be helpful to provide meaningful reference for noise reduction and control.

Analysis of Noise Characteristics of Double and Single-layered Porous Pavement with CPX Method -National Route 1, Sejong-Si Section-

Analysis of Noise Characteristics of Double and Single-layered Porous Pavement with CPX Method -National Route 1, Sejong-Si Section-

Analysis of noise characteristics of a diode generator in a multi-circuit system

In modern microwave electronics, it is extremely important to evaluate the possibility of efficient generation of highly stable oscillation modes and the creation of low-noise generators with a millimeter wavelength range. The purpose of the research was to determine the type of wave for the most effective modes of oscillation and to ensure the operation of various modes in the mode of mutual synchronization, which becomes possible because the real design of generators can include a number of reactive elements that form a number of resonant frequencies in the microwave range. This paper shows how it is possible to provide conditions for generation at a particular frequency and simultaneously obtain high stability of vibrations. The main research methods were: analysis and generalization of literature data and results of our own research on the peculiarities of oscillation generation in a multi-circuit system of a Gann diode generator and conditions under which high frequency stability is established; experimental studies using microwave spectrum analyzers, microwave devices. In this paper, the possible generation frequencies are calculated, the operation modes of the diode generator are studied, and their phase noise is experimentally measured. It is shown that when the generation frequency approaches the cut-off frequency of the waveguide with the help of structural elements or by changing the supply voltage, a mode of mutual synchronization of vibrations at high harmonics occurs using the H102 wave type in a very narrow range of frequency (phase) noise. A generator with a multicircuit resonant system was experimentally studied and a small amount of phase noise was obtained for both types of H101 and H102 waves. At the same time, the best parameters and noise characteristics occurred at the lowest types of vibration types. These results have an experimental novelty, which allows us to hope for the development of constructive solutions that provide the creation of highly stable low-noise generators of millimeter wavelength range with the minimum mass dimensional parameters.

Analysis of noise characteristics of spur face gear under different installation errors

Face gear drives have been widely used in helicopter drive system, but there are few research literatures on meshing noise. In order to study the relationship between installation errors and gear meshing noise, the tooth surface equation of spur face gear is derived based on the principle of gear shaping; Based on the virtual meshing relative position of gear shaper, pinion and spur face gear, the control equation of installation distance between pinion and spur face gear is derived; Based on the method of orthogonal test, the noise test scheme with installation errors is set up, and the meshing noise characteristics of spur face gear are obtained. The research provides a theoretical basis for the development of noise reduction technology of spur face gears.

Analysis of Noise Characteristics in Microseismic Monitoring

The effective signal energy of microseismic data is weak, and the received data will contain a lot of noise because of its special source excitation mode. At the same time, because the wave will inevitably lose energy in the process of propagation, the signal on the section is weak amplitude, weak continuity, even the effective signal on the whole line is submerged by noise, and the signal-to-noise ratio of the data is very low. In this paper, the common noise in different monitoring methods is analyzed, and the common processing methods in production are summarized.

新能源汽车和内燃机汽车噪声特性比较分析

新能源汽车和内燃机汽车噪声特性比较分析