Davide Piovesan^{1, *}, Roberto Bortoletto²

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.1, pp. 23-47, 2020, DOI:10.32604/cmes.2020.09231 - 01 April 2020

Abstract Exoskeletons are designed to control the forces exerted during the physical coupling between the human and the machine. Since the human is an active system, the control of an exoskeleton requires coordinated action between the machine and the load so to obtain a reciprocal adaptation. Humans in the control loop can be modeled as active mechanical loads whose stiffness is continuously changing. The direct measurement of human stiffness is difficult to obtain in real-time, thus posing a significant limitation to the design of wearable robotics controllers. Electromyographic (EMG) recordings can provide an indirect estimation of… More >

Sevan Goenezen^1,*, Ping Luo¹, Baik Jin Kim¹, Maulik Kotecha¹, Yue Mei^2,3

Molecular & Cellular Biomechanics, Vol.16, Suppl.2, pp. 46-48, 2019, DOI:10.32604/mcb.2019.07348

Abstract It is well known that the mechanical properties of tissues may vary spatially due to changing tissue types or due to inherent tissue disease. For example, the biomechanical properties are known to vary throughout blood vessels [1]. Diseases such as cancers may also lead to locally altered mechanical properties, thus allow a preliminary diagnosis via finger palpation. Quantifying the mechanical property distribution of tissues for a given constitutive equation will allow to characterize the biomechanical response of tissues. This may help to 1) predict disease progression, 2) diagnose diseases that alter the biomechanics of the… More >

Dawei Song^1,*, Nicholas Hugenberg², Assad A Oberai¹

Molecular & Cellular Biomechanics, Vol.16, Suppl.2, pp. 45-45, 2019, DOI:10.32604/mcb.2019.07138

Abstract Tractions exerted by cells on the extracellular matrix (ECM) are critical in many important physiological and pathological processes such as embryonic morphogenesis, cell migration, wound healing, and cancer metastasis. Traction Force Microscopy (TFM) is a robust tool to quantify cellular tractions during cell-matrix interactions. It works by measuring the motion of fiducial markers inside the ECM in response to cellular tractions and using this information to infer the traction field. Most applications of this technique have heretofore assumed that the ECM is homogeneous and isotropic [1], although the native ECM is typically composed of fibrous… More >

Yue Mei^1,2,3, Stephane Avril^3,*

Molecular & Cellular Biomechanics, Vol.16, Suppl.2, pp. 44-44, 2019, DOI:10.32604/mcb.2019.07034

Abstract Characterizing regional variations of material properties in soft tissues is essential for biomedical engineering and clinical medicine, including but not limited to cancerous disease detection and patient-specific surgical planning of cardiovascular diseases. Identification of nonhomogeneous material property distribution usually requires solving inverse problems in nonlinear elasticity. Generally, inverse algorithms can be categorized into two groups: iterative inversion and direct inversion. In direct inversion, the material property distribution of soft tissues is estimated directly from the equilibrium equations, while the inverse problem is posed as an optimization problem in iterative inversion. In this presentation, we compare… More >

Cosmin Anitescu¹, Elena Atroshchenko², Naif Alajlan³, Timon Rabczuk^3,*

CMC-Computers, Materials & Continua, Vol.59, No.1, pp. 345-359, 2019, DOI:10.32604/cmc.2019.06641

Abstract We present a method for solving partial differential equations using artificial neural networks and an adaptive collocation strategy. In this procedure, a coarse grid of training points is used at the initial training stages, while more points are added at later stages based on the value of the residual at a larger set of evaluation points. This method increases the robustness of the neural network approximation and can result in significant computational savings, particularly when the solution is non-smooth. Numerical results are presented for benchmark problems for scalar-valued PDEs, namely Poisson and Helmholtz equations, as More >

Shixiong Wang^1,∗, Jianhua He¹, Chen Wang², Xitong Li¹

Computer Systems Science and Engineering, Vol.33, No.5, pp. 379-387, 2018, DOI:10.32604/csse.2018.33.379

Abstract Many Engineering Problems could be mathematically described by FinalValue Problem, which is the inverse problem of InitialValue Problem. Accordingly, the paper studies the final value problem in the field of ODE problems and analyses the differences and relations between initial and final value problems. The more general new concept of the endpoints-value problem which could describe both initial and final problems is proposed. Further, we extend the concept into inner-interval value problem and arbitrary value problem and point out that both endpoints-value problem and inner-interval value problem are special forms of arbitrary value problem. Particularly, More >

Shaofei Ren^1,2, Guorong Chen² , Tiange Li² , Qijun Chen², Shaofan Li^{2, *}

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.3, pp. 287-307, 2018, DOI:10.31614/cmes.2018.04697

Abstract In this work, we have developed a novel machine (deep) learning computational framework to determine and identify damage loading parameters (conditions) for structures and materials based on the permanent or residual plastic deformation distribution or damage state of the structure. We have shown that the developed machine learning algorithm can accurately and (practically) uniquely identify both prior static as well as impact loading conditions in an inverse manner, based on the residual plastic strain and plastic deformation as forensic signatures. The paper presents the detailed machine learning algorithm, data acquisition and learning processes, and validation/verification 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 More >

Xu Liu¹, Guojian Shao¹, Xingxing Yue^2,*, Qingbin Yang³, Jingbo Su⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.2, pp. 189-211, 2018, DOI:10.31614/cmes.2018.03947

Abstract This paper aims to apply a virtual boundary element method (VBEM) to solve the inverse problems of three-dimensional heat conduction in orthotropic media. This method avoids the singular integrations in the conventional boundary element method, and can be treated as a potential approach for solving the inverse problems of the heat conduction owing to the boundary-only discretization and semi-analytical algorithm. When the VBEM is applied to the inverse problems, the numerical instability may occur if a virtual boundary is not properly chosen. The method encounters a highly ill-conditioned matrix for the larger distance between the… More >

K. Abe¹, H. Fujii¹, S. Yoshimura¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 71-87, 2017, DOI:10.3970/cmes.2017.113.068

Abstract Microscopic traffic simulations are useful for solving various traffic- related problems, e.g. traffic jams and accidents, local and global environmental and energy problems, maintaining mobility in aging societies, and evacuation plan- ning for natural as well as man-made disasters. The origin-destination (OD) matrix is often used as the input to represent traffic demands into traffic simulators. In this study, we propose an indirect method for estimating the OD matrix using a traffic simulator as an internal model. The proposed method is designed to output results that are consistent with the input of the simulator. The More >