Threshold determination method of Duffing chaotic system based on multi-scale entropy

Due to simple calculation and good denoising effect, wavelet threshold denoising method has been widely used in signal denoising. In this method, the threshold is an important parameter that affects the denoising effect. In order to improve the denoising effect of the existing methods, a new threshold considering interscale correlation is presented. Firstly, a new correlation index is proposed based on the propagation characteristics of the wavelet coefficients. Then, a threshold determination strategy is obtained using the new index. At the end of the paper, a simulation experiment is given to verify the effectiveness of the proposed method. In the experiment, four benchmark signals are used as test signals. Simulation results show that the proposed method can achieve a good denoising effect under various signal types, noise intensities, and thresholding functions.

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A Controllable Success Fix Rate Threshold Determination Method for GNSS Ambiguity Acceptance Tests

Remote Sensing ◽

10.3390/rs11070804 ◽

2019 ◽

Vol 11 (7) ◽

pp. 804 ◽

Cited By ~ 2

Author(s):

Lei Wang ◽

Ruizhi Chen ◽

Lili Shen ◽

Fu Zheng ◽

Yanming Feng ◽

...

Keyword(s):

Likelihood Ratio ◽

Failure Rate ◽

Test Theory ◽

Acceptance Test ◽

Determination Method ◽

Ratio Requirement ◽

Threshold Determination ◽

Gnss Data ◽

The Impact ◽

Acceptance Tests

GNSS integer ambiguity acceptance test is one of the open problems in GNSS data processing. A number of ambiguity acceptance tests have been proposed from different perspectives and then unified into the integer aperture estimation framework. The existing comparative studies indicate that the impact of test statistics form on the test performance is less critical, while how to construct an efficient, practical test threshold is still challenging. Based on the likelihood ratio test theory, a new computationally efficient ambiguity acceptance test with controllable success fix rate, namely the fixed likelihood ratio (FL-) approach is proposed, which does not require Monte Carlo simulation. The study indicates that the fixed failure rate (FF-) approach can only control the overall failure rate of the acceptance region, but the local failure rate is not controllable. The proposed FL-approach only accepts the fixed solution meeting the likelihood ratio requirement. With properly chosen likelihood ratio threshold, the FL-approach achieves comparable success rate as the FF-approach and even lower failure rate than the FF-approach for the strong underlying model cases. The fixed success fix rate of the FL-approach is verified with both simulation data and real GNSS data. The numerical results indicate that the success fix rate of the FL-approach achieves >98% while the failure rate is <1.5%. The RTK positioning with ambiguities tested by the FL-approach achieved 1–2cm horizontal precision and 2–4 cm vertical precision for all tested baselines, which confirms that the FL-approach can serve as a reliable and efficient threshold determination method for the GNSS ambiguity acceptance test problem.

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Multi-Scale Elastoplastic Dynamic Analysis of Steel Frame Welded Connections under Strong Earthquake Excitation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.501-504.1604 ◽

2014 ◽

Vol 501-504 ◽

pp. 1604-1608 ◽

Cited By ~ 1

Author(s):

Er Nian Zhao ◽

Wei Lian Qu

Keyword(s):

Dynamic Analysis ◽

Strong Earthquake ◽

Steel Frame ◽

Plane Section ◽

Scale Model ◽

Determination Method ◽

Contrastive Analysis ◽

Earthquake Excitation ◽

Multi Scale ◽

Flat Section

Multi-scale elastoplastic dynamic analysis of the welded connections is conducted under the strong earthquake excitation based on a steel frame engineering case. Two types of multi-scale model are built for the contrastive analysis, and the plastic deformation of the connection section is extracted to investigate the application of the plane-section assumption. The results indicate that elastic-plastic status makes the column and beam sections not meet the flat section assumption. Finally, the determination method of the refined modeling zone is studied based on the application of the plane-section assumption.

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