Jiali Liu¹, Mengge Yu^{2, *}, Dawei Chen¹, Zhigang Yang³

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.1, pp. 21-30, 2020, DOI:10.32604/fdmp.2020.07658

Abstract In order to investigate how the aerodynamic drag and noise produced by the roof air conditioner of a high-speed train can be reduced, the related unsteady flow in the near-field was computed using the method of large eddy simulation. In this way, the aerodynamic source for noise generation has initially been determined. Then, the far-field aerodynamic noise has been computed in the framework of the Lighthill’s acoustics analogy theory. The propulsion height and flow-guide angle of the roof air conditioner were set as the design variables. According to the computational results, a lower propulsion height or flow-guide angle is beneficial… More >

Ling Ding^{1, 2}, Huyin Zhang^{1, *}, Jinsheng Xiao³, Junfeng Lei³, Fang Xu³, Shejie Lu²

CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.2, pp. 675-690, 2020, DOI:10.32604/cmes.2020.07987

Abstract The ultimate goal of image denoising from video is to improve the given image, which can reduce noise interference to ensure image quality. Through denoising technology, image quality can have effectively optimized, signal-to-noise ratio can have increased, and the original mage information can have better reflected. As an important preprocessing method, people have made extensive research on image denoising algorithm. Video denoising needs to take into account the various level of noise. Therefore, the estimation of noise parameters is particularly important. This paper presents a noise estimation method based on variance stability transformation, which estimates the parameters of variance stability… More >

Yuan Chen¹, Liangtao Duan¹, Weize Sun^{2, *}, Jingxin Xu³

Journal on Big Data, Vol.1, No.3, pp. 107-116, 2019, DOI:10.32604/jbd.2019.07294

Abstract In this work, we address the frequency estimation problem of a complex singletone embedded in the heavy-tailed noise. With the use of the linear prediction (LP) property and l₁-norm minimization, a robust frequency estimator is developed. Since the proposed method employs the weighted l₁-norm on the LP errors, it can be regarded as an extension of the l_p-generalized weighted linear predictor. Computer simulations are conducted in the environment of α-stable noise, indicating the superiority of the proposed algorithm, in terms of its robust to outliers and nearly optimal estimation performance. More >

Jahede Tekeykhah¹, Seyed Mohsen Hosseini^2,*, Gholamali Jalali³, Jalil Alavi⁴, Abbas Esmaili Sari⁵

Sound & Vibration, Vol.53, No.6, pp. 263-276, 2019, DOI:10.32604/sv.2019.07157

Abstract Sound pollution is one of the most important urban problems which endangers mental and physical health of the residents. This study was aimed to assess the influence of different tree species, including Fraxinus rotundifolia, Robinia pseudoacacia, Platanus orientalis, Platycladus orientalis, and Pinus eldarica, in reducing noise pollution in the Abidar Forest Park. A further objective was to identify the contaminated areas of Sanandaj city and to propose suitable noise absorbent tree species in consistent conditions. For each tree stands the noise measurements were performed during intervals at frequencies of 250, 500 and 1000 Hz, besides an open area with the… More >

Li Li¹, Xiaopeng Fan¹, Kecheng Wu², Zhuanglei Zou¹, Yongyan Zhou¹, Dianhai Zhang^3,*, Ziyan Ren³, Yanli Zhang³

Sound & Vibration, Vol.53, No.6, pp. 251-262, 2019, DOI:10.32604/sv.2019.05252

Abstract In the current paper, which deals with the noise pollution excited by distribution transformers in the living area, a comprehensive treatment scheme is put forward for the purpose of reducing the sound pressure level emitting into the environment. In accordance with the associated test standard, the sound pressure levels of distribution transformer and surrounding environment are not only tested but analyzed as well. The measurements were carried out with the frequency analysis of the 1/3 octave resolution, with the center frequencies at 125 Hz, 250 Hz, 400 Hz, and 500 Hz. As illustrated, on the basis of the measurement results,… More >

Mahdi Soltanmohammadi¹, Vahid Monfared^2,*

Sound & Vibration, Vol.53, No.5, pp. 177-198, 2019, DOI:10.32604/sv.2019.05811

Abstract Dry-Type Cast Resin Distribution Transformers (CRT) is the secondgeneration of air-cooled distribution transformers where oil is replaced by resin for electrical insulation. CRT transformers may installed indoor adjacent to or near residential areas since they are clean and safe comparing to the conventional transformers. But, as it is obvious, noise discrepancy is intrinsically accompanied with all types of transformers and is inevitable for CRT transformers too. Minimization of noise level caused by such these transformers has biological and ergonomic importance. As it is known the core of transformers is the main source of the noise generation. In this paper, experimental… More >

Yongyun Zhu¹, Tao Zhang^1,*, Mohan Li², Di Wang¹, Shaoen Wu³

CMC-Computers, Materials & Continua, Vol.61, No.3, pp. 1305-1321, 2019, DOI:10.32604/cmc.2019.06406

Abstract The observation vectors in traditional coarse alignment contain random noise caused by the errors of inertial instruments, which will slow down the convergence rate. To solve the above problem, a real-time noise reduction method, sliding fixed-interval least squares (SFI-LS), is devised to depress the noise in the observation vectors. In this paper, the least square method, improved by a sliding fixed-interval approach, is applied for the real-time noise reduction. In order to achieve a better-performed coarse alignment, the proposed method is utilized to de-noise the random noise in observation vectors. First, the principles of proposed SFI-LS algorithm and coarse alignment… More >

Gouravaraju Saipraneeth¹, Ranjan Ganguli²

Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 23-64, 2011, DOI:10.3970/sdhm.2011.007.023

Abstract In this paper, the effect of damage on mode shape related parameters of a beam is investigated. The damage is represented by a localized reduction in beam stiffness. The damage location and amount is varied using a finite element model of the beam to obtain the mode shapes. A beam which is simply supported at both ends is used for the numerical results. The periodic nature of the beam is exploited to obtain spatial Fourier coefficients of the mode shapes. As the damage location and size are varied, it is found that the Fourier coefficients also change and are found… More >

A. Rama Mohan Rao¹, K. Lakshmi¹, Karthik Ganesan²

Structural Durability & Health Monitoring, Vol.9, No.2, pp. 99-128, 2013, DOI:10.32604/sdhm.2013.009.099

Abstract Development of efficient system identification techniques is highly relevant for large civil infrastructure for effective health monitoring, damage detection and vibration control. This paper presents a system identification scheme in time domain to estimate stiffness and damping parameters of structures using measured acceleration. Instead of solving the system identification problem as an inverse problem, we formulate it as an optimisation problem. Particle swarm optimisation (PSO) and its other variants has been a subject of research for the past few decades for solving complex optimisation problems. In this paper, a dynamic quantum behaved particle swarm optimisation algorithm (DQPSO) is proposed for… More >

Aleš Belšak¹, Jurij Prezelj²

Structural Durability & Health Monitoring, Vol.3, No.4, pp. 239-246, 2007, DOI:10.3970/sdhm.2007.003.239

Abstract Noise source vizualization represents an important tool in the field of technical acoustics. There are many different techniques of noise source visualization. Most of them, however, are intended for a specific noise source in a specific type of acoustic environment. Consequently, a certain visualization method can be used only for certain types of noise sources in a specific acoustic environment and in a restricted frequency area. This paper presents a new visualization method of complex noise sources on the basis of the use of an acoustic camera. A new algorithm has been used, which makes it possible to visualize all… More >