Application of Adaptive Wavelet Thresholding to Ultrasonic Signal Compression of Aluminum Alloy Forgings

2013 ◽  
Vol 658 ◽  
pp. 89-92
Author(s):  
Shou Shan Liu ◽  
Chuan Jiang Wang ◽  
Li Jun Bi ◽  
Chang Zhi Lv
Keyword(s):  
Aluminum Alloy ◽  
Ultrasonic Signal ◽  
Wavelet Thresholding ◽  
Signal Compression ◽  
Hard Thresholding ◽  
Coherent Noise ◽  
Adaptive Wavelet ◽  
Effective Signal ◽  
Thresholding Algorithm ◽  
The Mathematical Model

In this paper, for the purpose of ultrasonic signal compression and the coherent noise depressing in nondestructive test of aluminum alloy forging, the mathematical model of defect echoes is discussed and confirmed. And then the wavelet kernel is also confirmed according the waveform of the defect echoes. As the algorithms of standard hard thresholding and soft thresholding of wavelet transform can not bring out effective compression and depression to the coherent noise, an adaptive wavelet thresholding algorithm is introduced. Experimental results indicate that the adaptive wavelet thresholding algorithm can offer effective signal compression and depression to the coherent noise.

Method of Adaptive Wavelet Thresholding Used in Image Denoising

2011 ◽  
Vol 204-210 ◽  
pp. 1184-1187 ◽  
Author(s):  
Hui Xian Huang ◽  
Juan Gong ◽  
Te Zhang
Keyword(s):  
Correlation Coefficient ◽  
Adaptive Threshold ◽  
Wavelet Thresholding ◽  
Hard Thresholding ◽  
Adaptive Wavelet ◽  
Multi Resolution Analysis ◽  
Isolated Points ◽  
Resolution Analysis ◽  
Simulation Results ◽  
Traditional Approaches

According to multi-resolution analysis of wavelet threshold denoising principle, this paper presented two improved algorithms of continuity and adaptive threshold based on hard thresholding. The soft thresholding (hyperbolic thresholding) was used in the intervals after setting two thresholds, and the isolated points were removed according to the adjacent correlation coefficient during the processing. As a result, the hard thresholding’s shortcomings were reduced. The simulation results show that improved algorithms have both better visual effect and PSNR than the traditional approaches.

scholarly journals Modeling and Optimization of Bidirectional Clamping Forces in Drilling of Stacked Aluminum Alloy Plates

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2866
Author(s):  
Jintong Liu ◽  
Anan Zhao ◽  
Piao Wan ◽  
Huiyue Dong ◽  
Yunbo Bi
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Clamping Force ◽  
Practical Application ◽  
Element Simulation ◽  
Theory Of Plates ◽  
Plates And Shells ◽  
The Mathematical Model ◽  
The Relationship

Interlayer burrs formation during drilling of stacked plates is a common problem in the field of aircraft assembly. Burrs elimination requires extra deburring operations which is time-consuming and costly. An effective way to inhibit interlayer burrs is to reduce the interlayer gap by preloading clamping force. In this paper, based on the theory of plates and shells, a mathematical model of interlayer gap with bidirectional clamping forces was established. The relationship between the upper and lower clamping forces was investigated when the interlayer gap reaches zero. The optimization of the bidirectional clamping forces was performed to reduce the degree and non-uniformity of the deflections of the stacked plates. Then, the finite element simulation was conducted to verify the mathematical model. Finally, drilling experiments were carried out on 2024-T3 aluminum alloy stacked plates based on the dual-machine-based automatic drilling and riveting system. The experimental results show that the optimized bidirectional clamping forces can significantly reduce the burr heights. The work in this paper enables us to understand the effect of bidirectional clamping forces on the interlayer gap and paves the way for the practical application.

scholarly journals 2D Normalized Iterative Hard Thresholding Algorithm for Fast Compressive Radar Imaging

2017 ◽  
Vol 9 (6) ◽  
pp. 619 ◽  
Author(s):  
Gongxin Li ◽  
Jia Yang ◽  
Wenguang Yang ◽  
Yuechao Wang ◽  
Wenxue Wang ◽  
...  
Keyword(s):  
Radar Imaging ◽  
Hard Thresholding ◽  
Iterative Hard Thresholding ◽  
Thresholding Algorithm
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