Xueying Huang^*, Chun Yang^†, Chun Yuan^‡, Fei Liu^‡, Gador Canton^‡, Jie Zheng^§, Pamela K. Woodard^§, Gregorio A. Sicard^¶, Dalin Tang^||

Molecular & Cellular Biomechanics, Vol.6, No.2, pp. 121-134, 2009, DOI:10.3970/mcb.2009.006.121

Abstract Image-based computational models for atherosclerotic plaques have been developed to perform mechanical analysis to quantify critical flow and stress/strain conditions related to plaque rupture which often leads directly to heart attack or stroke. An important modeling issue is how to determine zero stress state from in vivo plaque geometries. This paper presents a method to quantify human carotid artery axial and inner circumferential shrinkages by using patient-specific ex vivo and in vivo MRI images. A shrink-stretch process based on patient-specific in vivo plaque morphology and shrinkage data was introduced to shrink the in vivo geometry first to find the zero-stress… More >

Chun Yang^∗,†, Dalin Tang^∗,‡, Shunichi Kobayashi^§, Jie Zheng^¶, Pamela K. Woodard^§, Zhongzhao Teng^*, Richard Bach^||, David N. Ku^∗∗

Molecular & Cellular Biomechanics, Vol.5, No.4, pp. 259-274, 2008, DOI:10.3970/mcb.2008.005.259

Abstract Many acute cardiovascular syndromes such as heart attack and stroke are caused by atherosclerotic plaque ruptures which often happen without warning. MRI-based models with fluid-structure interactions (FSI) have been introduced to perform flow and stress/strain analysis for atherosclerotic plaques and identify possible mechanical and morphological indices for accurate plaque vulnerability assessment. In this paper, cyclic bending was added to 3D FSI coronary plaque models for more accurate mechanical predictions. Curvature variation was prescribed using the data of a human left anterior descending (LAD) coronary artery. Five computational models were constructed based on ex vivo MRI human coronary plaque data to… More >

Dalin Tang^*, Chun Yang^†, Tal Geva^‡,§, Pedro J. del Nido^¶

Molecular & Cellular Biomechanics, Vol.4, No.3, pp. 159-176, 2007, DOI:10.3970/mcb.2007.004.159

Abstract A single-layer isotropic patient-specific right/left ventricle and patch (RV/LV/Patch) combination model with fluid-structure interactions (FSI) was introduced in our previous papers to evaluate and optimize human pulmonary valve replacement/insertion (PVR) surgical procedure and patch design. In this paper, an active anisotropic model with two-layer structure for ventricle wall and tissue fiber orientation was introduced to improve previous isotropic model for more accurate assessment of RV function and potential application in PVR surgery and patch design. A material-stiffening approach was used to model active heart contraction. The computational models were used to conduct ``virtual (computational)'' surgeries and test the hypothesis that… More >

Shaojiang Zhong^{1, *}

CMC-Computers, Materials & Continua, Vol.60, No.2, pp. 465-479, 2019, DOI:10.32604/cmc.2019.05853

Abstract Based on the three-dimensional classic Chua circuit, a nonlinear circuit containing two flux-control memristors is designed. Due to the difference in the design of the characteristic equation of the two magnetron memristors, their position form a symmetrical structure with respect to the capacitor. The existence of chaotic properties is proved by analyzing the stability of the system, including Lyapunov exponent, equilibrium point, eigenvalue, Poincare map, power spectrum, bifurcation diagram et al. Theoretical analysis and numerical calculation show that this heterogeneous memristive model is a hyperchaotic five-dimensional nonlinear dynamical system and has a strong chaotic behavior. Then, the memristive system is… More >

Chun Yang^1,2, Dalin Tang², Satya Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.1, pp. 53-78, 2011, DOI:10.3970/cmes.2011.072.053

Abstract Previously, we introduced a computational procedure based on three-dimensional meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Structure-only models were used in our previous report. In this paper, fluid-stricture interaction (FSI) was added to improve on prediction accuracy. One participating patient was scanned three times (T1, T2, and T3, at intervals of about 18 months) to obtain plaque progression data. Blood flow was assumed to laminar, Newtonian, viscous and incompressible. The Navier-Stokes equations with arbitrary Lagrangian-Eulerian (ALE) formulation were used as the governing… More >

Chun Yang^1,2, Dalin Tang^2,3 Satya Atluri⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.57, No.1, pp. 51-76, 2010, DOI:10.3970/cmes.2010.057.051

Abstract Cardiovascular disease (CVD) is becoming the number one cause of death worldwide. Atherosclerotic plaque rupture and progression are closely related to most severe cardiovascular syndromes such as heart attack and stroke. Mechanisms governing plaque rupture and progression are not well understood. A computational procedure based on three-dimensional meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data was introduced to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Participating patients were scanned three times (T1, T2, and T3, at intervals of about 18 months) to obtain plaque progression data. Vessel wall thickness (WT) changes… More >

Dalin Tang¹, Chun Yang^1,2, Tal Geva^3,4, Glenn Gaudette⁴, and Pedro J. del Nido⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.56, No.2, pp. 113-130, 2010, DOI:10.3970/cmes.2010.056.113

Abstract Right and left ventricle (RV/LV) combination models with three different patch materials (Dacron scaffold, treated pericardium, and contracting myocardium), two-layer construction, fiber orientation, and active anisotropic material properties were introduced to evaluate the effects of patch materials on RV function. A material-stiffening approach was used to model active heart contraction. Cardiac magnetic resonance (CMR) imaging was performed to acquire patient-specific ventricular geometries and cardiac motion from a patient with severe RV dilatation due to pulmonary regurgitation needing RV remodeling and pulmonary valve replacement operation. Computational models were constructed and solved to obtain RV stroke volume, ejection fraction, patch area variations,… More >

Chun Yang¹, Dalin Tang², Chun Yuan³, William Kerwin², Fei Liu³, Gador Canton³, Thomas S. Hatsukami^3,4, Satya Atluri⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.2, pp. 95-108, 2008, DOI:10.3970/cmes.2008.028.095

Abstract Atherosclerotic plaque rupture and progression have been the focus of intensive investigations in recent years. Plaque rupture is closely related to most severe cardiovascular syndromes such as heart attack and stroke. A computational procedure based on meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data was introduced to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Participating patients were scanned three times (T₁,T₂, and T₃, at intervals of about 18 months) to obtain plaque progression data. Vessel wall thickness (WT) changes were used as the measure for plaque progression. Since there was insufficient… More >

Chun Yang¹, Dalin Tang², Chun Yuan³, Thomas S. Hatsukami⁴, Jie Zheng⁵, Pamela K. Woodard⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.3, pp. 233-246, 2007, DOI:10.3970/cmes.2007.019.233

Abstract It has been recognized that fluid-structure interactions (FSI) play an important role in cardiovascular disease initiation and development. However, in vivo MRI multi-component FSI models for human carotid atherosclerotic plaques with bifurcation and quantitative comparisons of FSI models with fluid-only or structure-only models are currently lacking in the literature. A 3D non-Newtonian multi-component FSI model based on in vivo/ex vivo MRI images for human atherosclerotic plaques was introduced to investigate flow and plaque stress/strain behaviors which may be related to plaque progression and rupture. Both artery wall and plaque components were assumed to be hyperelastic, isotropic, incompressible and homogeneous. Blood… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.2, pp. 145-162, 2007, DOI:10.3970/cmes.2007.019.145

Abstract A new method is developed to solve the Dirichlet problems for the two-dimensional Laplace equation in the doubly-connected domains, namely the meshless regularized integral equations method (MRIEM), which consists of three portions: Fourier series expansion, the Fredholm integral equations, and linear equations to determine the unknown boundary conditions onartificial circles. The boundary integral equations on artificial circles are singular-free and the kernels are degenerate. When boundary-type methods are inefficient to treat the problems with complicated domains, the new method can be applicable for such problems. The new method by using the Fourier series and the Fourier coefficients can be adopted… More >