1
|
Ji Y, Wang H. A Revised Hilbert⁻Huang Transform and Its Application to Fault Diagnosis in a Rotor System. SENSORS 2018; 18:s18124329. [PMID: 30544598 PMCID: PMC6308445 DOI: 10.3390/s18124329] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/20/2018] [Accepted: 12/04/2018] [Indexed: 11/16/2022]
Abstract
As a classical method to deal with nonlinear and nonstationary signals, the Hilbert–Huang transform (HHT) is widely used in various fields. In order to overcome the drawbacks of the Hilbert–Huang transform (such as end effects and mode mixing) during the process of empirical mode decomposition (EMD), a revised Hilbert–Huang transform is proposed in this article. A method called local linear extrapolation is introduced to suppress end effects, and the combination of adding a high-frequency sinusoidal signal to, and embedding a decorrelation operator in, the process of EMD is introduced to eliminate mode mixing. In addition, the correlation coefficients between the analyzed signal and the intrinsic mode functions (IMFs) are introduced to eliminate the undesired IMFs. Simulation results show that the improved HHT can effectively suppress end effects and mode mixing. To verify the effectiveness of the new HHT method with respect to fault diagnosis, the revised HHT is applied to analyze the vibration displacement signals in a rotor system collected under normal, rubbing, and misalignment conditions. The simulation and experimental results indicate that the revised HHT method is more reliable than the original with respect to fault diagnosis in a rotor system.
Collapse
Affiliation(s)
- Yongjian Ji
- School of Mechanical and Electrical Engineering, Beijing Information Science & Technology University, Haidian, Qinghe Xiaoying Donglu No. 12, Beijing 100192, China.
- School of Mechanical Engineering, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian District, Beijing 100081, China.
| | - Hongjun Wang
- School of Mechanical and Electrical Engineering, Beijing Information Science & Technology University, Haidian, Qinghe Xiaoying Donglu No. 12, Beijing 100192, China.
- Key Laboratory of Modern Measurement and Control Technology, Ministry of Education, BISTU, Haidian, Qinghe Xiaoying Donglu No. 12, Beijing 100192, China.
| |
Collapse
|
2
|
Gao Z, Li Y, Sun Y, Yang J, Xiong H, Zhang H, Liu X, Wu W, Liang D, Li S. Motion Tracking of the Carotid Artery Wall From Ultrasound Image Sequences: a Nonlinear State-Space Approach. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:273-283. [PMID: 28866487 DOI: 10.1109/tmi.2017.2746879] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The motion of the common carotid artery (CCA) wall has been established to be useful in early diagnosis of atherosclerotic disease. However, tracking the CCA wall motion from ultrasound images remains a challenging task. In this paper, a nonlinear state-space approach has been developed to track CCA wall motion from ultrasound sequences. In this approach, a nonlinear state-space equation with a time-variant control signal was constructed from a mathematical model of the dynamics of the CCA wall. Then, the unscented Kalman filter (UKF) was adopted to solve the nonlinear state transfer function in order to evolve the state of the target tissue, which involves estimation of the motion trajectory of the CCA wall from noisy ultrasound images. The performance of this approach has been validated on 30 simulated ultrasound sequences and a real ultrasound dataset of 103 subjects by comparing the motion tracking results obtained in this study to those of three state-of-the-art methods and of the manual tracing method performed by two experienced ultrasound physicians. The experimental results demonstrated that the proposed approach is highly correlated with (intra-class correlation coefficient ≥ 0.9948 for the longitudinal motion and ≥ 0.9966 for the radial motion) and well agrees (the 95% confidence interval width is 0.8871 mm for the longitudinal motion and 0.4159 mm for the radial motion) with the manual tracing method on real data and also exhibits high accuracy on simulated data (0.1161 ~ 0.1260 mm). These results appear to demonstrate the effectiveness of the proposed approach for motion tracking of the CCA wall.
Collapse
|
4
|
Gao L, Zhang Y, Zhou Y, Hu X, Deng L, Zhang K, Cai G, Zhang J. Compound Doppler ultrasound signal simulation for pulsatile carotid arteries with a stenosis. Biomed Mater Eng 2016; 27:131-48. [PMID: 27567770 DOI: 10.3233/bme-161573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The simulated Doppler blood flow signals are widely used to assess the performance of the clutter filters for removing wall components while reserving low-velocity signals scattered from physiological blood flow approaching the inner vessel-wall injured by a stenosed lesion. OBJECTIVE By simultaneously taking into account the natural attributes of the Doppler equipment, blood flow as well as vessel wall of pulsatile carotid arteries with a stenosis, a computer simulation method is presented to produce the compound Doppler ultrasound blood flow signals. METHODS The in-phase and quadrature (I/Q) axial as well as radial blood flow signals are simulated by superposing a series of cosine functions regulated by the spectrograms estimated from the axial and radial velocity profiles firstly obtained through the solution of the incompressible Navier-Stokes equations, respectively. Meanwhile, the I/Q Doppler signals echoed from pulsatile near (anterior) and far (posterior) walls are reproduced based on their radial movements during a cardiac cycle. Ultimately, those confirmed quadrature signals are summed to generate the compound Doppler signals including the contribution from both blood flow and stenosed vessel-wall. RESULTS The compound Doppler ultrasound signals echoed from both axial and radial blood flows as well as vessel walls with obstruction grades of 0% (normal arteries), 10% and 25% are simulated respectively. The real signals from the left carotid artery with an approximately 10% stenosis degree are also collected for further assessing the believability of simulated versions. CONCLUSIONS The simulated and clinical tests demonstrate that the proposed computer simulation method can produce compound Doppler signals with confirmed qualitative and quantitative characteristics resembled with the clinical versions, which could be used as an theoretical data source for evaluating the performance of the signal separation between pulsatile blood flows and vessel walls with mild stenosed-lesions.
Collapse
Affiliation(s)
- Lian Gao
- Department of Electronic Engineering, Information School, Yunnan University, Kunming, Yunnan 650091, China. E-mails: , , , , , ,
| | - Yufeng Zhang
- Department of Electronic Engineering, Information School, Yunnan University, Kunming, Yunnan 650091, China. E-mails: , , , , , ,
| | - Yi Zhou
- Department of Electronic Engineering, Information School, Yunnan University, Kunming, Yunnan 650091, China. E-mails: , , , , , ,
| | - Xiao Hu
- Department of Electronic Engineering, Information School, Yunnan University, Kunming, Yunnan 650091, China. E-mails: , , , , , ,
| | - Li Deng
- Department of Electronic Engineering, Information School, Yunnan University, Kunming, Yunnan 650091, China. E-mails: , , , , , ,
| | - Kexin Zhang
- Cardiovascular Department, The Second Affiliated Hospital of Kunming Medical College, Kunming, Yunnan 650031, China. E-mail:
| | - Guanghui Cai
- Department of Electronic Engineering, Information School, Yunnan University, Kunming, Yunnan 650091, China. E-mails: , , , , , ,
| | - Junhua Zhang
- Department of Electronic Engineering, Information School, Yunnan University, Kunming, Yunnan 650091, China. E-mails: , , , , , ,
| |
Collapse
|
5
|
Gao L, Zhang Y, Zhang K, Cai G, Zhang J, Shi X. A computer simulation model for Doppler ultrasound signals from pulsatile blood flow in stenosed vessels. Comput Biol Med 2012; 42:906-14. [PMID: 22841363 DOI: 10.1016/j.compbiomed.2012.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 07/03/2012] [Indexed: 11/29/2022]
Abstract
A computer simulation model based on an analytic flow velocity distribution is proposed to generate Doppler ultrasound signals from pulsatile blood flow in the vessels with various stenosis degrees. The model takes into account the velocity field from pulsatile blood flow in the stenosed vessels, sample volume shape and acoustic factors that affect the Doppler signals. By analytically solving the Navier-Stokes equations, the velocity distributions of pulsatile blood flow in the vessels with various stenosis degrees are firstly calculated according to the velocity at the axis of the circular tube. Secondly, power spectral density (PSD) of the Doppler signals is estimated by summing the contribution of all scatterers passing through the sample volume grouped into elemental volumes. Finally, Doppler signals are generated using cosine-superposed components that are modulated by the PSD functions that vary over the cardiac cycle. The results show that the model generates Doppler blood flow signals with characteristics similar to those found in practice. It could be concluded that the proposed approach offers the advantages of computational simplicity and practicality for simulating Doppler ultrasound signals from pulsatile blood flow in stenosed vessels.
Collapse
Affiliation(s)
- Lian Gao
- Department of Electronic Engineering, Information School, Yunnan University, and Cardiovascular Department, The Second Affiliated Hospital of Kunming Medical College, Kunming, Yunnan 650091, China
| | | | | | | | | | | |
Collapse
|