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Unsupervised seismic data deblending based on the convolutional autoencoder regularization

Xue Yaru, Chen Yuyao, Jiang Minhui, Duan Hanting, Niu Libo, Chen Chong

Acta Geophysica

2022

Vol. 70, no 3

1171--1182

Simultaneous source technology can provide high-quality seismic data with lower acquisition costs. However, a deblending algorithm is needed to suppress the blending noise. The supervised deep learning methods are effective, but are usually limited by the lack of labels. To solve the problem, we propose an unsupervised deep learning method based on acquisition system. A convolutional autoencoder (CAE) network is employed to predict the deblending results of the input pseudodeblended data. And then, the deblending results will be re-blended using the given blending operator. The parameters of CAE will be optimized by the difference between re-blended data and input data, which is defined as ‘blending loss.’ The blending problem is ill-posed but the CAE can be regarded as an implicit regularization term which constrains the solving process to obtain the desire solution. A numerical test on synthetic data demonstrates that the proposed method can converge to correct results and two field data experiments verify the flexibility and effectiveness of our model. The transfer training method is also used to improve model performance.

Segmentary strategy in modeling of cardiovascular system with blood supply to regional skin

Li Zhongyou, Jiang Wentao, Diao Junjie, Chen Chong, Xu Kairen, Fan Haidong, Yan Fei

Biocybernetics and Biomedical Engineering

2021

Vol. 41, no. 4

1505--1517

Objective: The focus of this study is to model the cardiovascular system (CS) involving regional skin blood flow (SBF) to gain new insights into the skin-CS relationship. Methods: A lumped parameter model with a series of electrical components was developed to model the CS involving SBF. Four parts were considered: the heart, arterial circulation, microcirculation (including the skin and other tissues), and the venous system. The model was validated based on previous publications. Additionally, the body surface was divided into seven blocks replaced by lumped resistances in this model, including the head, upper limbs and neck, chest and back, anterolateral abdomen, posterior abdomen, lower limbs, and buttocks. The SBF of each block was described using a weighted average method (relative ratio of cutaneous blood perfusion and regional body surface area) Results: Cardiodynamics characterized the properties of cardiac cycles, including isovolumic contraction, accelerated ejection, decelerated ejection, isovolumic diastole, and filling phases. Blood flow and pulse pressure in the arterial trunk declined and increased, respectively, from the aorta root to the distal portion, exhibiting normal cardiovascular properties. Accordingly, the blood pressure of the arterial branches attached to the arterial trunk also satisfied normal physiological characteristics; the blood flow of all the arterial branches exhibited good agreement with previous studies. Additionally, the modeled SBF of each region was consistent with the data from the weighted average method. Conclusion: This model effectively demonstrates the normal properties of the CS that involves regional SBF and may be promising in the prediction of the skin-CS relationship.

Numerical insights into the determinants of stent performance for the management of aneurysm with a visceral vessel attached

Li Zhongyou, Chen Chong, Chen Yu, Wang Zhenze, Jiang Wentao, Tian Xiaobao

Acta of Bioengineering and Biomechanics

2021

Vol. 23, no. 2

41--53

Purpose: As the factors affecting the efficacy of the bare-metal stent in the treatment of aneurysm with a visceral vessel attached were not fully understood, we aimed to discuss the effects of different characteristics of the stent on the hemodynamics and flexibility in the treatment of the aneurysm. Methods: Single-layer (with different strut widths) and multi-layer (with a different number of struts) stent models divided into three porosity groups, with porosities of 72.3, 60.5, and 52.4%, were modeled for a comparison of their hemodynamic isolation and flexibility performance via computational fluid dynamics and finite element methods. Results: The velocity and timeaveraged wall shear stress decreased more noticeably with multi-layer stent interventions. A higher oscillatory shear index and relative residence time occurred at the aneurysmal sac wall after multi-layer stents were employed. Time-averaged wall shear stress on the aneurysmal wall decreased with an increase in the number of struts or a decrease in pore size, but oscillatory shear index and relative residence time increased as the number of struts increased or the pore size decreased. Besides, all stents affect the branch patency slightly. In the bending test, when the porosity exceeded 60.5%, multi-layer stents were more flexible. Conclusion: The number of struts or pore size of stent dominated the isolation in the management of the aneurysm and affected the flexibility significantly when the porosity was below 60.5%. These findings may contribute to the special design of the stent in the treatment of such types of aneurysms.