Open Access
ARTICLE
Mahdi Soltanmohammadi1, Vahid Monfared2,*
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 >
Open Access
ARTICLE
Cheng Hu*
Sound & Vibration, Vol.53, No.5, pp. 199-206, 2019, DOI:10.32604/sv.2019.07712
Abstract Taking the complex mechanical systems as the research project, a theoretical multi-degree-of-freedom (MDOF) model was established. Based on the
vibration characteristics analysis of this system, a novel method of vibration mitigation was proposed, which can be applied to most of the complex mechanical
systems. Through this method, limited grounding stiffness was made use of
and added to certain degree of freedom (DOF) discretely. Thus, the root-meansquare (RMS) of the systems amplitude can be reduced to ideal level. The
MATLAB code based on this method was attached, which was tested on the theoretical model. Consider that complex mechanical systems are nonlinear… More >
Open Access
ARTICLE
Roohalah Hajizadeh1, Ali Khavanin2,*, Mohammad Barmar3, Ahmad Jonidi Jafari4, Somayeh Farhang Dehghan5
Sound & Vibration, Vol.53, No.5, pp. 207-222, 2019, DOI:10.32604/sv.2019.06523
Abstract Polyurethane foam as the most well-known absorbent materials has a
suitable absorption coefficient only within a limited frequency range. The aim
of this study was to improve the sound absorption coefficient of flexible polyurethane
(PU) foam within the range of various frequencies using clay nanoparticles,
polyacrylonitrile nanofibers, and polyvinylidene fluoride nanofibers. The
response surface method was used to determine the effect of addition of nanofi-
bers of PAN and PVDF, addition of clay nanoparticles, absorbent thickness,
and air gap on the sound absorption coefficient of flexible polyurethane foam
(PU) across different frequency ranges. The absorption coefficient of the samples
was… More >
Open Access
ARTICLE
J.K. Mohanty1, A. Adarsh2, P.R. Dash1, K. Parida1, P.K. Pradhan1,*
Sound & Vibration, Vol.53, No.5, pp. 223-235, 2019, DOI:10.32604/sv.2019.07737
Abstract Condition monitoring is implementation of the advanced diagnostic
techniques to reduce downtime and to increase the efficiency and reliability.
The research is for determining the usage of advanced techniques like Vibration
analysis, Oil analysis and Thermography to diagnose ensuing problems of the
Plant and Machinery at an early stage and plan to take corrective and preventive
actions to eliminate the forthcoming breakdown and enhancing the reliability of
the system. Nowadays, the most of the industries have adopted the condition
monitoring techniques as a part of support system to the basic maintenance strategies.
Major condition monitoring technique they follow is Vibration… More >
Open Access
ARTICLE
Yixiong Yu*
Sound & Vibration, Vol.53, No.5, pp. 237-243, 2019, DOI:10.32604/sv.2019.07887
Abstract Mining aeroengine operational data and developing fault diagnosis
models for aeroengines are to avoid running aeroengines under undesired conditions.
Because of the complexity of working environment and faults of aeroengines,
it is unavoidable that the monitored parameters vary widely and possess
larger noise levels. This paper reports the extrapolation of a diagnosis model
for 20 gas path faults of a double-spool turbofan civil aeroengine. By applying
support vector machine (SVM) algorithm together with genetic algorithm (GA),
the fault diagnosis model is obtained from the training set that was based on
the deviations of the monitored parameters superimposed with the noise… More >
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