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International Journal for Numerical Methods in Biomedical Engineering

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https://www.readbyqxmd.com/read/28425587/hybrid-finite-difference-finite-element-immersed-boundary-method
#1
Boyce E Griffith, Xiaoyu Luo
The immersed boundary method is an approach to fluid-structure interaction that uses a Lagrangian description of the structural deformations, stresses, and forces along with an Eulerian description of the momentum, viscosity, and incompressibility of the fluid-structure system. The original immersed boundary methods described immersed elastic structures using systems of flexible fibers, and even now, most immersed boundary methods still require Lagrangian meshes that are finer than the Eulerian grid. This work introduces a coupling scheme for the immersed boundary method to link the Lagrangian and Eulerian variables that facilitates independent spatial discretizations for the structure and background grid...
April 20, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28425209/identification-of-dynamic-load-for-prosthetic-structures
#2
Dequan Zhang, Xu Han, Zhongpu Zhang, Jie Liu, Chao Jiang, Nobuhiro Yoda, Xianghua Meng, Qing Li
Dynamic load exists in numerous biomechanical systems and its identification signifies a critical issue for characterizing dynamic behaviors and studying biomechanical consequence of the systems. This study aims to identify dynamic load in the dental prosthetic structures, namely three-unit implant-supported fixed partial denture (I-FPD) and teeth-supported fixed partial denture (T-FPD). The three-dimensional (3D) finite element (FE) models were constructed through patient's computerized tomography (CT) images...
April 20, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28425201/numerical-analysis-of-crimping-and-inflation-process-of-balloon-expandable-coronary-stent-using-implicit-solution
#3
Jakub Bukala, Piotr Kwiatkowski, Jerzy Malachowski
The paper presents an applied methodology for numerical Finite Element analysis of coronary stent crimping and the free inflation process with the use of a folded non-compliant angioplasty balloon. The use of an implicit scheme is considered as the most original part of the work, as an explicit finite element procedure is very often preferred. Hitherto, when the implicit solution was used for the Finite Element solution, the simulated issue was largely simplified. Therefore, the authors focused on the modelling methodology with minimum possible simplification, i...
April 20, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28388837/effective-sparse-representation-of-x-ray-medical-images
#4
Laura Rebollo-Neira
Effective sparse representation of X-Ray medical images within the context of data reduction is considered. The proposed framework is shown to render an enormous reduction in the cardinality of the data set required to represent this class of images at very good quality. The goal is achieved by a) creating a dictionary of suitable elements for the image decomposition in the wavelet domain and b) applying effective greedy strategies for selecting the particular elements which enable the sparse decomposition of the wavelet coefficients...
April 7, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28349647/finite-element-modeling-validation-and-parametric-investigations-of-a-retinal-reattachment-stent
#5
Razvan Rusovici, Dennis Dalli, Kunal Mitra, Gary Ganiban, Michael Grace, Rudy Mazzocchi, Michael Calhoun
A new retinal reattachment surgical procedure is based on a stent which is deployed to press the retina back in place. An eye-stent finite element model studied the strain induced by the stent on retina. FEM simulations were performed for several stent geometric configurations (number of loops, wire diameter, intraocular pressure). The FEM was validated against experiment. Parametric studies demonstrated that stents could be successfully designed so that the maximum strain would be below permanent damage strain threshold of 2%...
March 27, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28337862/bayesian-sensitivity-analysis-of-a-1d-vascular-model-with-gaussian-process-emulators
#6
A Melis, R H Clayton, A Marzo
One-dimensional models of the cardiovascular system can capture the physics of pulse waves, but involve many parameters. Since these may vary among individuals, patient-specific models are difficult to construct. Sensitivity analysis can be used to rank model parameters by their effect on outputs, and to quantify how uncertainty in parameters influences output uncertainty. This type of analysis is often conducted with a Monte Carlo method, where large numbers of model runs are used to assess input-output relations...
March 24, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28329435/face-shield-design-against-blast-induced-head-injuries
#7
Long Bin Tan, Kwong Ming Tse, Yuan Hong Tan, Mohamad Ali Bin Sapingi, Vincent Beng Chye Tan, Heow Pueh Lee
Blast-induced traumatic brain injury (TBI) has been on the rise in recent years due to the increasing use of improvised explosive devices (IEDs) in conflict zones. Our study investigates the response of a helmeted human head subjected to a blast of 1 atm peak overpressure, for cases with and without a standard polycarbonate (PC) face shield and for face shields comprising of composite PC and aerogel materials and with lateral edge extension. The novel introduction of aerogel into the laminate face shield is explored and its wave-structure interaction mechanics and performance in blast mitigation is analysed...
March 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28294580/effect-of-cerebrospinal-fluid-modelling-on-spherically-convergent-shear-waves-during-blunt-head-trauma
#8
Amit Madhukar, Ying Chen, Martin Ostoja-Starzewski
The MRI-based computational model, previously validated by tagged MRI and HARP imaging analysis technique on in vivo human brain deformation, is employed to study transient wave dynamics during blunt head trauma. Three different constitutive models are used for the cerebrospinal fluid (CSF): incompressible solid elastic, viscoelastic and fluid-like elastic using an equation of state model. Three impact cases are simulated which indicate that the blunt impacts give rise not only to a fast pressure wave but also to a slow, and potentially much more damaging, shear (distortional) wave that converges spherically towards the brain center...
March 14, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28294574/phase-field-boundary-conditions-for-the-voxel-finite-cell-method-surface-free-stress-analysis-of-ct-based-bone-structures
#9
L H Nguyen, S K F Stoter, T Baum, J S Kirschke, M Ruess, Z Yosibash, D Schillinger
The voxel finite cell method employs unfitted finite element meshes and voxel quadrature rules to seamlessly transfer CT data into patient-specific bone discretizations. The method, however, still requires the explicit parametrization of boundary surfaces to impose traction and displacement boundary conditions, which constitutes a potential roadblock to automation. We explore a phase-field based formulation for imposing traction and displacement constraints in a diffuse sense. Its essential component is a diffuse geometry model generated from metastable phase-field solutions of the Allen-Cahn problem that assumes the imaging data as initial condition...
March 11, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28268244/calculation-of-cancellous-bone-elastic-properties-with-the-polarization-based-fft-iterative-scheme
#10
Lucas Colabella, Ariel Alejandro Ibarra Pino, Josefina Ballarre, Piotr Kowalczyk, Adrián Pablo Cisilino
The FFT based method, originally introduced by Moulinec and Suquet in 1994 has gained popularity for computing homogenized properties of composites. In this work, the method is used for the computational homogenization of the elastic properties of cancellous bone. To the authors' knowledge, this is the first study where the FFT scheme is applied to bone mechanics. The performance of the method is analyzed for artificial and natural bone samples of two species: bovine femoral heads and implanted femurs of Hokkaido rats...
March 7, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28264145/human-body-modeling-method-to-simulate-the-biodynamic-characteristics-of-spine-in-vivo-with-different-sitting-postures
#11
Rui-Chun Dong, Li-Xin Guo
The aim of this study is to model the computational model of seated whole human body including skeleton, muscle, viscera, ligament, intervertebral disc, and skin to predict effect of the factors (sitting postures, muscle and skin, buttocks, viscera, arms, gravity, and boundary conditions) on the biodynamic characteristics of spine. Two finite element models of seated whole body and a large number of finite element models of different ligamentous motion segments were developed and validated. Static, modal, and transient dynamic analyses were performed...
March 6, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28257608/research-and-primary-evaluation-of-an-automatic-fusion-method-for-multi-source-tooth-crown-data
#12
Ning Dai, Dawei Li, Xu Yang, Cheng Cheng, Yuchun Sun
BACKGROUND: With the development of 3D scanning technologies in dentistry, high accuracy optical scanning data from the crown and cone beam computed tomography (CBCT) data from the root can be acquired easily. In many dental fields, especially in digital orthodontics, it is useful to fuse the data from the crown and the root. However, the manual fusion method is complex and difficult. A novel automatic fusion method for two-source data from the crown and the root was researched and its accuracy was evaluated in this study...
March 3, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28249103/a-hybrid-computational-model-to-explore-the-topological-characteristics-of-epithelial-tissues
#13
Ismael González-Valverde, José Manuel García Aznar
Epithelial tissues show a particular topology where cells resemble a polygon-like shape, but some biological processes can alter this tissue topology. During cell proliferation, mitotic cell dilation deforms the tissue and modifies the tissue topology. Additionally, cells are reorganized in the epithelial layer and these rearrangements also alter the polygon distribution. We present here a computer-based hybrid framework focused on the simulation of epithelial layer dynamics that combines discrete and continuum numerical models...
March 1, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28226417/an-efficient-multistage-algorithm-for-full-calibration-of-the-hemodynamic-model-from-bold-signal-responses
#14
Brian Zambri, Rabia Djellouli, Taous-Meriem Laleg-Kirati
We propose a computational strategy that falls into the category of prediction/correction iterative-type approaches, for calibrating the hemodynamic model. The proposed method is used to estimate consecutively the values of the two sets of model parameters. Numerical results corresponding to both synthetic and real functional magnetic resonance imaging measurements for a single stimulus as well as for multiple stimuli are reported to highlight the capability of this computational methodology to fully calibrate the considered hemodynamic model...
February 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28226410/patient-specific-computational-modeling-of-cortical-spreading-depression-via-diffusion-tensor-imaging
#15
Julia M Kroos, Isabella Marinelli, Ibai Diez, Jesus M Cortes, Sebastiano Stramaglia, Luca Gerardo-Giorda
Cortical Spreading Depression (CSD), a depolarization wave originating in the visual cortex and traveling towards the frontal lobe, is commonly accepted as a correlate of migraine visual aura. As of today, little is known about the mechanisms that can trigger or stop such phenomenon. However, the complex and highly individual characteristics of the brain cortex suggest that the geometry might have a significant impact in supporting or contrasting the propagation of CSD. Accurate patient-specific computational models are fundamental to cope with the high variability in cortical geometries among individuals, but also with the conduction anisotropy induced in a given cortex by the complex neuronal organisation in the grey matter...
February 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28224760/a-tree-parenchyma-coupled-model-for-lung-ventilation-simulation
#16
N Pozin, S Montesantos, I Katz, M Pichelin, I Vignon-Clementel, C Grandmont
In this article we develop a lung-ventilation model. The parenchyma is described as an elastic homogenized media. It is irrigated by a space-filling dyadic resistive pipe network, which represents the tracheo-bronchial tree. In this model the tree and the parenchyma are strongly coupled. The tree induces an extra viscous term in the system constitutive relation, which leads, in the finite element framework, to a full matrix. We consider an efficient algorithm that takes advantage of the tree structure to enable a fast matrix-vector product computation...
February 22, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28208231/fast-left-ventricle-tracking-using-localized-anatomical-affine-optical-flow
#17
Sandro Queirós, João L Vilaça, Pedro Morais, Jaime C Fonseca, Jan D'hooge, Daniel Barbosa
In daily clinical cardiology practice, left ventricle (LV) global and regional function assessment is crucial for disease diagnosis, therapy selection and patient follow-up. Currently, this is still a time-consuming task, spending valuable human resources. In this work, a novel fast methodology for automatic LV tracking is proposed based on localized anatomically constrained affine optical flow. This novel method can be combined to previously proposed segmentation frameworks or manually delineated surfaces at an initial frame to obtain fully delineated datasets and, thus, assess both global and regional myocardial function...
February 16, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28205412/an-investigation-of-dimensional-scaling-using-cervical-spine-motion-segment-finite-element-models
#18
Dilaver Singh, Duane S Cronin
The paucity of experimental data for validating computational models of different statures underscores the need for appropriate scaling methods so that models can be verified and validated using experimental data. Scaling was investigated using 50th percentile male (M50) and 5th percentile female (F05) cervical spine motion segment (C4-C5) finite element models subject to tension, flexion, and extension loading. Two approaches were undertaken: geometric scaling of the models to investigate size effects (volumetric scaling) and scaling of the force-displacement or moment-angle model results (data scaling)...
February 15, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28146314/how-coagulation-zone-size-is-underestimated-in-computer-modeling-of-rf-ablation-by-ignoring-the-cooling-phase-just-after-rf-power-is-switched-off
#19
Ramiro M Irastorza, Macarena Trujillo, Enrique Berjano
All the numerical models developed for radiofrequency ablation so far have ignored the possible effect of the cooling phase (just after radiofrequency power is switched off) on the dimensions of the coagulation zone. Our objective was thus to quantify the differences in the minor radius of the coagulation zone computed by including and ignoring the cooling phase. We built models of RF tumor ablation with 2 needle-like electrodes: a dry electrode (5 mm long and 17G in diameter) with a constant temperature protocol (70°C) and a cooled electrode (30 mm long and 17G in diameter) with a protocol of impedance control...
February 1, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/27343200/third-order-harmonic-expansion-of-the-magnetoencephalography-forward-and-inverse-problems-in-an-ellipsoidal-brain-model
#20
Mauricio Alcocer-Sosa, David Gutiérrez
We present a forward modeling solution in the form of an array response kernel for magnetoencephalography. We consider the case when the brain's anatomy is approximated by an ellipsoid and an equivalent current dipole model is used to approximate brain sources. The proposed solution includes the contributions up to the third-order ellipsoidal harmonic terms; hence, we compare this new approximation against the previously available one that only considered up to second-order harmonics. We evaluated the proposed solution when used in the inverse problem of estimating physiologically feasible visual evoked responses from magnetoencephalography data...
April 2017: International Journal for Numerical Methods in Biomedical Engineering
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