Zhijie Huang^1,2,3, Zuyu Chen^1,2,3, Xiaodan Ren^4,*, Jing Hu³, Xuedong Zhang³, Lu Hai⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.118, No.1, pp. 139-155, 2019, DOI:10.31614/cmes.2019.04596

Abstract Damage and threats to hydraulic and submarine structures by underwater explosions (UNDEXs) have raised much attention. The centrifuge model test, compared to prototype test, is a more promising way to examine the problem while reducing cost and satisfying the similitude requirements of both Mach and Froude numbers simultaneously. This study used a systematic approach employing centrifuge model tests and numerical simulations to investigate the effects of UNDEXs on an air-backed steel plate. Nineteen methodical centrifuge tests of UNDEXs were conducted. The shock wave pressure, bubble oscillation pressure, acceleration and the strain of the air-backed steel plate were recorded and compared… More >

Marco Götz^1,*, Ferenc Leichsenring¹, Thomas Kropp², Peter Müller², Tobias Falk², Wolfgang Graf¹, Michael Kaliske¹, Welf-Guntram Drossel²

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.3, pp. 387-423, 2018, DOI:10.31614/cmes.2018.04112

Abstract Numerical mechanical models used for design of structures and processes are very complex and high-dimensionally parametrised. The understanding of the model characteristics is of interest for engineering tasks and subsequently for an efficient design. Multiple analysis methods are known and available to gain insight into existing models. In this contribution, selected methods from various fields are applied to a real world mechanical engineering example of a currently developed clinching process. The selection of introduced methods comprises techniques of machine learning and data mining, in which the utilization is aiming at a decreased numerical effort. The methods of choice are basically… More >

R. E. Jones^1,*, J. A. Templeton¹, C. M. Sanders¹, J. T. Ostien¹

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.3, pp. 309-342, 2018, DOI:10.31614/cmes.2018.04285

Abstract We use machine learning (ML) to infer stress and plastic flow rules using data from representative polycrystalline simulations. In particular, we use so-called deep (multilayer) neural networks (NN) to represent the two response functions. The ML process does not choose appropriate inputs or outputs, rather it is trained on selected inputs and output. Likewise, its discrimination of features is crucially connected to the chosen inputoutput map. Hence, we draw upon classical constitutive modeling to select inputs and enforce well-accepted symmetries and other properties. In the context of the results of numerous simulations, we discuss the design, stability and accuracy of… More >

Zhengwei Li^1,2, Jianli Wang^1,*, Tao Chen¹, Bin Wang¹, Yuanhao Wu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.2, pp. 271-286, 2018, DOI:10.31614/cmc.2018.04005

Abstract With the development of adaptive optics and post restore processing techniques, large aperture ground-based telescopes can obtain high-resolution images (HRIs) of targets. The pose of the space target can be estimated from HRIs by several methods. As the target features obtained from the image are unstable, it is difficult to use existing methods for pose estimation. In this paper a method based on real-time target model matching to estimate the pose of space targets is proposed. First, the physically-constrained iterative deconvolution algorithm is used to obtain HRIs of the space target. Second, according to the 3D model, the ephemeris data,… More >

Li Ding¹, Jiasheng Zhang,^1,2, Hongchang Sun^3,*

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.2, pp. 213-229, 2018, DOI:10.31614/cmes.2018.03981

Abstract In order to ensure the safety of fluid flow in deep-water submarine pipelines, a safe and energy-saving built-in skin effect electric heat tracing technology was adopted as the thermal management strategy. The magnetic field distribution of built-in skin effect heating system is analyzed based on the mechanism of built-in skin effect heating system, so as to obtain the equivalent circuit model of built-in skin effect electric heating system. Meanwhile, heating power is introduced as an intermediate variable to establish the relationship between power supply frequency and built-in skin effect heating temperature. Aiming at the skin effect electric heating system, an… More >

A. Parassuram^1,*, P. Somasundaram¹

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.2, pp. 169-187, 2018, DOI:10.31614/cmes.2018.01720

Abstract A continuous-time Model Predictive Controller was proposed using Kautz function in order to improve the performance of Load Frequency Control (LFC). A dynamic model of an interconnected power system was used for Model Predictive Controller (MPC) design. MPC predicts the future trajectory of the dynamic model by calculating the optimal closed loop feedback gain matrix. In this paper, the optimal closed loop feedback gain matrix was calculated using Kautz function. Being an Orthonormal Basis Function (OBF), Kautz function has an advantage of solving complex pole-based nonlinear system. Genetic Algorithm (GA) was applied to optimally tune the Kautz function-based MPC. A… More >

Zhou Zhao¹, Boyan Mao², Youjun Liu², Haisheng Yang², Yu Chen^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.116, No.2, pp. 229-245, 2018, DOI: 10.31614/cmes.2018.04192

Abstract In coronary artery bypass grafting (CABG), graft’s poor instant patency may lead to an abnormal hemodynamic environment in anastomosis, which could further cause graft failure after the surgery. This paper investigates the graft hemodynamics with different instant patency, and explores its effect on graft postoperative efficiency. Six CABG 0D/3D coupling multi-scale models which used left internal mammary artery (LIMA) and saphenous vein (SVG) as grafts were constructed. Different types of grafts were examined in the models, including normal grafts, grafts with competitive flow and grafts with anastomotic stenosis. Simulation results indicated that comparing with SVG grafts, there was a greater… More >

Long Deng¹, Xueying Huang^2,3,*, Heng Zuo⁴, Yuan Zheng², Chun Yang⁵, Yunhu Song¹, Dalin Tang⁶

CMES-Computer Modeling in Engineering & Sciences, Vol.116, No.2, pp. 115-125, 2018, DOI: 10.31614/cmes.2018.04076

Abstract The mechanisms of systolic anterior motion (SAM) of the mitral valve in hypertrophic obstructive cardiomyopathy (HOCM) remain unclear. To investigate the angle of attack between blood flow and mitral valve leaflets at pre-SAM time point, patient-specific CT-based computational models were constructed for 5 patients receiving septal myectomy surgery to obtain pre- and post-operative 2D vector flow mapping. The comparisons between pre- and post-operative angles of attack based on 2D vector flow mapping of 5 patients were performed. It was found that there was no statistically significant difference between pre- and post-operative angles of attack (61.1±t wao vs. 56.2±56.o, p=0.306, n=5).… More >

Yanxia Wang¹, Yu Wang², Siqi Li³, ur Rehman Aziz³, Shutian Liu¹, Kairong Qin^2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.116, No.2, pp. 127-147, 2018, DOI: 10.31614/cmes.2018.03985

Abstract Assessment of the magnitude and pattern of wall shear stress (WSS) in vivo is the prerequisite for studying the quantitative relationship between exercise-induced WSS and arterial endothelial function. In the previous studies, the calculation of the WSS modulated by exercise training was primarily based upon the rigid tube model, which did not take non-linear effects of vessel elastic deformation into consideration. In this study, with an elastic tube model, we estimated the effect of a bout of 30-minute acute cycling exercise on the WSS and the flow rate in the common carotid artery according to the measured inner diameter, center-line… More >

Fengjuan Wang^1,2, Shengping Wu^1,2,*, Jinyang Jiang^1,2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.116, No.1, pp. 1-10, 2018, DOI: 10.31614/cmes.2018.03834

Abstract Corrosion inhibition performances of three purine derivatives were investigated systematically by employing DFT and molecular modeling. The relationship between macroscopic inhibition efficiency and quantum chemical properties was discussed from multiple perspectives, based on frontier orbital theory, and Fukui function theories. Comparative experimental and theoretical studies were taken, indicating the inhibition efficiency could be analyzed in the order of guanine <2,6-diaminopurine <2,6-dithiopurine. The sulphur atom (S5) was validated to be the most susceptible site for electrophile via quantitative surface analysis. More >