Conducted and radiated noise reduction using circuit balance on double switch converter

2010 ◽  
Author(s):  
Nimit Boonpirom
Keyword(s):  
Noise Reduction ◽  
Radiated Noise ◽  
Double Switch

Nascent Noise Reduction Strategies for Underwater Vehicles

Volume 1 ◽  
2004 ◽  
Author(s):  
Promode R. Bandyopadhyay
Keyword(s):  
Noise Reduction ◽  
Artificial Muscle ◽  
Underwater Vehicles ◽  
Drive Train ◽  
Forward Speed ◽  
High Lift ◽  
Radiated Noise ◽  
Rotational Rate ◽  
Reduction Strategies

Noise reduction concepts applicable to small underwater vehicles and in the nascent stages of research, are considered. These questions are asked. How to lower the propulsor rotational rate while maintaining forward speed? How to reduce blade tonal? How to supplant the propulsor drive train, which is the main source of hull vibration and radiated noise? The highlights of progress in passive and active approaches are reviewed. The approaches are inspired by unsteady high lift principles employed in flying and swimming animals and by emerging artificial muscle technology.

Radiated Noise Reduction in a Single Cylinder Direct Injection (DI) Naturally Aspirated (NA) Engine

2011 ◽  
Author(s):  
Sudhakara Naidu T ◽  
Chaitanya Krishna Balla ◽  
Chris carlson ◽  
David Hudson
Keyword(s):  
Noise Reduction ◽  
Direct Injection ◽  
Single Cylinder ◽  
Radiated Noise

scholarly journals Layout Method of Damping Material for Gearbox Based on Acoustic Contribution

2019 ◽  
Vol 37 (4) ◽  
pp. 757-766
Author(s):  
Yunong Liu ◽  
Lan Liu ◽  
Geng Liu ◽  
Liyan Wu ◽  
Chao Liu ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Present Method ◽  
Element Model ◽  
Low Noise ◽  
Radiated Noise ◽  
Damping Material ◽  
Plate Area ◽  
Acoustic Contribution ◽  
Reduction Effect ◽  
Damping Materials

In order to realize the low noise design of marine gearbox, a layout method of damping materials for gearbox based on acoustic contribution was proposed. The present method can accurately and effectively determine the additional area of damping materials and achieve greatly the noise reduction effect. Firstly, taking a marine single-stage herringbone gearbox as the object, the finite element/boundary element model for the reducer structure was established. After applying the vibration excitation of the gear system, the radiated noise of each field point was solved. Secondly, by analyzing the acoustic transfer vector (ATV) and modal acoustic contribution (MAC), the surface of the gearbox was partitioned, and the partitioned surface was analyzed by using panel acoustic contribution (PAC). Finally, the damping material was added to the plate area which contributes greatly to the radiated noise, and the effect of the noise reduction under different schemes were compared. The results show that the layout design of damping materials based on the present method can reduce the radiation noise of observation points accurately and effectively in the range of 0~4 000 Hz.

scholarly journals Composite cylinder cross section tailoring for radiated noise reduction

1993 ◽  
Vol 94 (3) ◽  
pp. 1839-1839
Author(s):  
Colin P. Ratcliffe ◽  
Roger M. Crane ◽  
Armando L. Santiago
Keyword(s):  
Noise Reduction ◽  
Cross Section ◽  
Composite Cylinder ◽  
Radiated Noise

Noise Reduction of Engine Component Covers Using the Finite Element Method

1991 ◽  
Author(s):  
Jayaraman Sivakumar ◽  
Shung H. Sung ◽  
Donald J. Nefske
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Noise Reduction ◽  
Forced Vibration ◽  
Integral Method ◽  
Element Model ◽  
The Finite Element Method ◽  
Structural Modifications ◽  
Radiated Noise ◽  
Engine Component

Abstract Radiated noise from an engine component cover is predicted by using a structural finite element model of the cover to predict its forced vibration response, and then by using the Rayleigh integral method to predict its radiated noise. Applications to evaluate the radiated noise from an engine rocker cover and an engine front cover are presented. Measurements of the radiated noise from actual covers installed on a running engine show the predicted noise reduction due to structural modifications is achieved.

scholarly journals A New Feature Extraction Method for Ship-Radiated Noise Based on Improved CEEMDAN, Normalized Mutual Information and Multiscale Improved Permutation Entropy

Entropy ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 624 ◽  
Author(s):  
Zhe Chen ◽  
Yaan Li ◽  
Renjie Cao ◽  
Wasiq Ali ◽  
Jing Yu ◽  
...  
Keyword(s):  
Feature Extraction ◽  
Mutual Information ◽  
Noise Reduction ◽  
Extraction Method ◽  
Recognition Rate ◽  
Permutation Entropy ◽  
Feature Extraction Method ◽  
Normalized Mutual Information ◽  
Radiated Noise ◽  
New Feature

Extracting useful features from ship-radiated noise can improve the performance of passive sonar. The entropy feature is an important supplement to existing technologies for ship classification. However, the existing entropy feature extraction methods for ship-radiated noise are less reliable under noisy conditions because they lack noise reduction procedures or are single-scale based. In order to simultaneously solve these problems, a new feature extraction method is proposed based on improved complementary ensemble empirical mode decomposition with adaptive noise (ICEEMDAN), normalized mutual information (norMI), and multiscale improved permutation entropy (MIPE). Firstly, the ICEEMDAN is utilized to obtain a group of intrinsic mode functions (IMFs) from ship-radiated noise. The noise reduction process is then conducted by identifying and eliminating the noise IMFs. Next, the norMI and MIPE of the signal-dominant IMFs are calculated, respectively; and the norMI is used to weigh the corresponding MIPE result. The multi-scale entropy feature is finally defined as the sum of the weighted MIPE results. Experimental results show that the recognition rate of the proposed method achieves 90.67% and 83%, respectively, under noise free and 5 dB conditions, which is much higher than existing entropy feature extraction algorithms. Hence, the proposed method is more reliable and suitable for feature extraction of ship-radiated noise in practice.

Underwater radiated noise reduction technology using sawtooth duct for pumpjet propulsor

2019 ◽  
Vol 188 ◽  
pp. 106228 ◽  
Author(s):  
Denghui Qin ◽  
Guang Pan ◽  
Seongkyu Lee ◽  
Qiaogao Huang ◽  
Yao Shi
Keyword(s):  
Noise Reduction ◽  
Radiated Noise ◽  
Underwater Radiated Noise

scholarly journals Optimization of the Housing Shape Design for Radiated Noise Reduction of an Agricultural Electric Vehicle Gearbox

2020 ◽  
Vol 10 (23) ◽  
pp. 8414
Author(s):  
Gwan-Hee Son ◽  
Beom-Soo Kim ◽  
Seung-Je Cho ◽  
Young-Jun Park
Keyword(s):  
Noise Reduction ◽  
Electric Vehicle ◽  
Computing Time ◽  
Optimization Technique ◽  
Operating Conditions ◽  
Structural Vibration ◽  
Shape Design ◽  
Fe Model ◽  
Radiated Noise ◽  
Noise Characteristics

As the demand for agricultural electric vehicles increases, it is becoming important to conduct noise reduction in consideration of the characteristics of an electric powertrain. This study was conducted to optimize the shape design of gearbox housing for radiated noise reduction of an agricultural electric vehicle gearbox. The noise and vibration of the gearbox were measured considering the noise characteristics of the electric vehicle gearbox, which radiates high-frequency pure tone noise. The main noise source radiated by the structural vibration of the gearbox housing was identified and considered when modeling the loading conditions in the numerical analysis. To improve the reliability, the finite element (FE) model was updated and validated. Internal machine elements were modeled as a substructure through a reduced-order modeling method to reduce the computing time and apply a constant gear excitation force. The weak areas of structure were determined and it was used as the design area for optimization. The topology optimization technique was used to reduce the equivalent radiated power (ERP) which was used as an indicator of radiated noise level. The maximum value of the ERP decreased under all operating conditions at the rated speed.

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