scholarly journals STUDY ON STRUCTURAL-ACOUSTIC CHARACTERISTICS OF CYLINDRICAL SHELL BASED ON WAVENUMBER SPECTRUM ANALYSIS METHOD

Brodogradnja ◽  
2021 ◽  
Vol 72 (2) ◽  
pp. 57-71
Author(s):  
Liu Wenxi ◽  
◽  
Guan Huiren ◽  
Zhou Qidou ◽  
Lou Jingjun
Keyword(s):  
Spectrum Analysis ◽  
Axial Direction ◽  
Exciting Force ◽  
Structural Vibration ◽  
Normal Velocity ◽  
Analysis Method ◽  
Radiated Noise ◽  
Distribution Form ◽  
Wavenumber Spectrum ◽  
The Moment

By the finite element method, the structural vibration response is calculated under the action of the axial exciting force and the moment with different distribution form, and then the transfer function of the mean square normal velocity is analyzed. The wavenumber spectrum analysis method is used to separate and quantify the shell vibration in the wavenumber domain, and then the relation between the structural vibration characteristics and the structural wavelength is summarized. It is concluded that the structural vibration and radiated noise can be reduced under the symmetric action of axial exciting force and the moment. Based on the above conclusion, a symmetrical thrust bearing supporting system is designed and the stiffness of the supporting structure in the axial direction is controlled by selecting suitable size of structural members, therefore, the structural vibration and radiated noise of the submarine is reduced significantly.

Influences of Diaphragm Springs on Operation Performances of Sight-Stabilizing Mechanism

2011 ◽  
Vol 211-212 ◽  
pp. 384-388
Author(s):  
Gui Mei Guo ◽  
Lin Hong
Keyword(s):  
Rigid Body ◽  
Structural Parameters ◽  
Angular Displacement ◽  
Kinematics And Dynamics ◽  
Analysis Method ◽  
Structure Form ◽  
Simulation Results ◽  
Fix Point ◽  
The Moment

Sight-stabilizing mechanisms controlled by diaphragm springs and other damping elements is an important subordinate system of airborne sight stabilizing System. The performances of sight-stabilizing system depend on the characteristics of kinematics and dynamics of the system in a great extent. Among various external moments acting on the rod of the manipulator, such as those moments caused by damper, positioning spring, and restoration spring, the forces by diaphragm springs are most obvious. According to the structure form and motion peculiarity, the rod can be equivalent to a rigid body turning around a fix point. Simulation results reveal that the moment of the restoration spring to the rod is proportional to the angular displacement, and that the moment is the most prominent factor influencing the operating performances among all these moments. Through reasonable adjustments of structural parameters of the restoration spring, the performances of the sight-stabilizing system can be improved greatly; the analysis method provides a basis for guiding the design of concerned structural parameters of sight-stabilizing system.

scholarly journals Ship Radiated Noise Recognition Using Resonance-Based Sparse Signal Decomposition

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Jiaquan Yan ◽  
Haixin Sun ◽  
En Cheng ◽  
Xiaoyan Kuai ◽  
Xiaoliang Zhang
Keyword(s):  
Feature Extraction ◽  
Low Frequency ◽  
Signal Decomposition ◽  
Sparse Signal ◽  
Support Vector ◽  
Analysis Method ◽  
Radiated Noise ◽  
High Resonance ◽  
Residual Component ◽  
Sparse Signal Decomposition

Under the complex oceanic environment, robust and effective feature extraction is the key issue of ship radiated noise recognition. Since traditional feature extraction methods are susceptible to the inevitable environmental noise, the type of vessels, and the speed of ships, the recognition accuracy will degrade significantly. Hence, we propose a robust time-frequency analysis method which combines resonance-based sparse signal decomposition (RSSD) and Hilbert marginal spectrum (HMS) analysis. First, the observed signals are decomposed into high resonance component, low resonance component, and residual component by RSSD, which is a nonlinear signal analysis method based not on frequency or scale but on resonance. High resonance component is multiple simultaneous sustained oscillations, low resonance component is nonoscillatory transients, and residual component is white Gaussian noises. According to the low-frequency periodic oscillatory characteristic of ship radiated noise, high resonance component is the purified ship radiated noise. RSSD is suited to noise suppression for low-frequency oscillation signals. Second, HMS of high resonance component is extracted by Hilbert-Huang transform (HHT) as the feature vector. Finally, support vector machine (SVM) is adopted as a classifier. Real audio recordings are employed in the experiments under different signal-to-noise ratios (SNRs). The experimental results indicate that the proposed method has a better recognition performance than the traditional method under different SNRs.

Response Spectrum Analysis of a Large-Span Hangar Subjected to Multi-Dimensional Seismic Inputs

2013 ◽  
Vol 639-640 ◽  
pp. 906-910
Author(s):  
Yang Xu ◽  
Jun Zhao ◽  
Xiao Yan Xu ◽  
Dan Zhu
Keyword(s):  
Spectrum Analysis ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Analysis Method ◽  
Response Spectrum Analysis ◽  
Roof Structure ◽  
Internal Forces ◽  
Primary Direction ◽  
Lateral Displacements ◽  
2D And 3D

The multi-dimensional seismic response of a single-span hangar was studied by response spectrum analysis method. The lateral displacements of the structure, forces of its supporting columns and its roof structure were calculated and compared with each other for cases of one-, two- and three-dimensional (1D, 2D and 3D) seismic inputs. The results show that, compared with the case of 1D earthquake input, the effects of horizontally 2D earthquake inputs on the internal forces and displacements of its supporting columns in the primary direction of input are obvious when it is along the symmetrical axis of the hangar and their effects in the secondary direction of input are even more important which results in great increases of the internal forces and displacements in that direction. The vertical seismic input has almost no effect on the internal forces and displacements of columns. The internal forces in different parts of the roof structure are controlled by horizontal or vertical inputs, respectively, and, compared with those from horizontally or vertically 1D inputs, the responses from 3D inputs are increased and the effects should be considered in seismic design.

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