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Finite element modeling

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https://www.readbyqxmd.com/read/28549379/dynamically-tunable-plasmon-induced-transparency-in-on-chip-graphene-based-asymmetrical-nanocavity-coupled-waveguide-system
#1
Pingping Qiu, Weibin Qiu, Zhili Lin, Houbo Chen, Junbo Ren, Jia-Xian Wang, Qiang Kan, Jiao-Qing Pan
A graphene-based on-chip plasmonic nanostructure composed of a plasmonic bus waveguide side-coupled with a U-shaped and a rectangular nanocavities has been proposed and modeled by using the finite element method in this paper. The dynamic tunability of the plasmon-induced transparency (PIT) windows has been investigated. The results reveal that the PIT effects can be tuned via modifying the chemical potential of the nanocavities and plasmonic bus waveguide or by varying the geometrical parameters including the location and width of the rectangular nanocavity...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28548920/evaluation-of-biofidelity-of-thums-pedestrian-model-under-a-whole-body-impact-conditions-with-a-generic-sedan-buck
#2
Taotao Wu, Taewung Kim, Varun Bollapragada, David Poulard, Huipeng Chen, Matthew B Panzer, Jason L Forman, Jeff R Crandall, Bengt Pipkorn
OBJECTIVE: The goal of this study was to evaluate the biofidelity of the Total Human Model for Safety (THUMS; Ver. 4.01) pedestrian finite element models (PFEM) in a whole-body pedestrian impact condition using a well-characterized generic pedestrian buck model. METHODS: The biofidelity of THUMS PFEM was evaluated with respect to data from 3 full-scale postmortem human subject (PMHS) pedestrian impact tests, in which a pedestrian buck laterally struck the subjects using a pedestrian buck at 40 km/h...
May 29, 2017: Traffic Injury Prevention
https://www.readbyqxmd.com/read/28548240/viscoelastic-computational-modeling-of-the-human-head-neck-system-eigenfrequencies-and-time-dependent-analysis
#3
E Boccia, A Gizzi, C Cherubini, M G C Nestola, S Filippi
A subject-specific three-dimensional viscoelastic finite element model of the human head-neck system is presented and investigated based on Computed Tomography and Magnetic Resonance biomedical images. Ad hoc imaging processing tools are developed for the reconstruction of the simulation domain geometry and the internal distribution of bone and soft tissues. Materials viscoelastic properties are characterized point-wise through an image-based interpolating function used then for assigning the constitutive prescriptions of a heterogenous viscoelastic continuum model...
May 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28548237/simulation-of-non-linear-transient-elastography-finite-element-model-for-the-propagation-of-shear-waves-in-homogeneous-soft-tissues
#4
W Ye, A Bel-Brunon, S Catheline, A Combescure, M Rochette
In this study, visco-hyperelastic Landau's model which is widely used in acoustical physic field is introduced into a finite element formulation. It is designed to model the non-linear behaviour of finite amplitude shear waves in soft solids, typically, in biological tissues. This law is employed in finite element models based on elastography experiments reported in [1], the simulations results show a good agreement with the experimental studyred: it is observed in both that a plane shear wave generates only odd harmonics and a nonplane wave generates both odd and even harmonics in the spectral domain...
May 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28547995/adsorption-induced-deformation-of-hierarchically-structured-mesoporous-silica-effect-of-pore-level-anisotropy
#5
Christian Balzer, Anna M Waag, Stefan Gehret, Gudrun Reichenauer, Florian Putz, Nicola Hüsing, Oskar Paris, Noam Bernstein, Gennady Y Gor, Alexander V Neimark
The goal of this work is to understand adsorption-induced deformation of hierarchically structured porous silica exhibiting well-defined cylindrical mesopores. For this purpose, we performed an in situ dilatometry measurement on a calcined and sintered monolithic silica sample during the adsorption of N2 at 77 K. To analyze the experimental data, we extended the adsorption stress model to account for the anisotropy of cylindrical mesopores, i.e., we explicitly derived the adsorption stress tensor components in the axial and radial direction of the pore...
May 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28547660/rib-geometry-explains-variation-in-dynamic-structural-response-potential-implications-for-frontal-impact-fracture-risk
#6
Michelle M Murach, Yun-Seok Kang, Samuel D Goldman, Michelle A Schafman, Stephen H Schlecht, Kevin Moorhouse, John H Bolte, Amanda M Agnew
The human thorax is commonly injured in motor vehicle crashes, and despite advancements in occupant safety rib fractures are highly prevalent. The objective of this study was to quantify the ability of gross and cross-sectional geometry, separately and in combination, to explain variation of human rib structural properties. One hundred and twenty-two whole mid-level ribs from 76 fresh post-mortem human subjects were tested in a dynamic frontal impact scenario. Structural properties (peak force and stiffness) were successfully predicted (p < 0...
May 25, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/28545933/extracting-multidimensional-stimulus-response-correlations-using-hybrid-encoding-decoding-of-neural-activity
#7
REVIEW
Jacek P Dmochowski, Jason Ki, Paul DeGuzman, Paul Sajda, Lucas C Parra
In neuroscience, stimulus-response relationships have traditionally been analyzed using either encoding or decoding models. Here we propose a hybrid approach that decomposes neural activity into multiple components, each representing a portion of the stimulus. The technique is implemented via canonical correlation analysis (CCA) by temporally filtering the stimulus (encoding) and spatially filtering the neural responses (decoding) such that the resulting components are maximally correlated. In contrast to existing methods, this approach recovers multiple correlated stimulus-response pairs, and thus affords a richer, multidimensional analysis of neural representations...
May 22, 2017: NeuroImage
https://www.readbyqxmd.com/read/28545891/numerical-modelling-of-methane-oxidation-efficiency-and-coupled-water-gas-heat-reactive-transfer-in-a-sloping-landfill-cover
#8
S Feng, C W W Ng, A K Leung, H W Liu
Microbial aerobic methane oxidation in unsaturated landfill cover involves coupled water, gas and heat reactive transfer. The coupled process is complex and its influence on methane oxidation efficiency is not clear, especially in steep covers where spatial variations of water, gas and heat are significant. In this study, two-dimensional finite element numerical simulations were carried out to evaluate the performance of unsaturated sloping cover. The numerical model was calibrated using a set of flume model test data, and was then subsequently used for parametric study...
May 22, 2017: Waste Management
https://www.readbyqxmd.com/read/28545718/the-effect-of-glenoid-component-version-and-humeral-polyethylene-liner-rotation-on-subluxation-and-impingement-in-reverse-shoulder-arthroplasty
#9
Vijay N Permeswaran, Andrea Caceres, Jessica E Goetz, Donald D Anderson, Carolyn M Hettrich
BACKGROUND: A previously validated finite element modeling approach was used to determine how changes in glenoid component version and polyethylene liner rotation within the humeral component affect the arm abduction angle at which impingement between the inferior glenoid and the polyethylene liner occurs as well as the amount of subluxation generated by that impingement. MATERIALS AND METHODS: Five glenoid component versions (5° anteversion; neutral; 5°, 10°, and 20° retroversion) and 7 polyethylene liner rotations (20° and 10° anterior; neutral; 10°, 20°, 30°, and 40° posterior) were considered, resulting in 35 different clinically representative models...
May 22, 2017: Journal of Shoulder and Elbow Surgery
https://www.readbyqxmd.com/read/28544835/leaflet-mechanical-properties-of-carpentier-edwards-perimount-magna-pericardial-aortic-bioprostheses
#10
Heide Kuang, Yue Xuan, Michelle Lu, Aart Mookhoek, Andrew D Wisneski, Julius M Guccione, Liang Ge, Elaine E Tseng
BACKGROUND: Transcatheter aortic valve replacement (TAVR) has recently been shown to be equivalent to surgical aortic valve replacement (SAVR) in intermediate-risk patients. As TAVR expands towards the traditionally SAVR population, TAVR versus SAVR durability becomes increasingly important. While the durability of TAVR is unknown, valve design - particularly with regards to leaflet stress - impacts on valve durability. Although leaflet stress cannot be measured directly, it can be determined using finite element modeling, with such models requiring the mechanical properties of the leaflets...
January 2017: Journal of Heart Valve Disease
https://www.readbyqxmd.com/read/28544575/analysis-of-physical-characteristics-of-tumor-treating-fields-for-human-glioblastoma
#11
Edwin Lok, Pyay San, Van Hua, Melissa Phung, Eric T Wong
Tumor Treating Fields (TTFields) therapy is an approved treatment that has known clinical efficacy against recurrent and newly diagnosed glioblastoma. However, the distribution of the electric fields and the corresponding pattern of energy deposition in the brain are poorly understood. To evaluate the physical parameters that may influence TTFields, postacquisition MP-RAGE, T1 and T2 MRI sequences from a responder with a right parietal glioblastoma were anatomically segmented and then solved using finite-element method to determine the distribution of the electric fields and rate of energy deposition at the gross tumor volume (GTV) and other intracranial structures...
May 23, 2017: Cancer Medicine
https://www.readbyqxmd.com/read/28543540/computational-modeling-of-915-mhz-microwave-ablation-comparative-assessment-of-temperature-dependent-tissue-dielectric-models
#12
Garron Deshazer, Mark Hagmann, Derek Merck, Jan Sebek, Kent B Moore, Punit Prakash
PURPOSE: The objective of this study is to develop a computational model for simulating 915 MHz microwave ablation (MWA), and verify the simulation predictions of transient temperature profiles against experimental measurements. Due to the limited experimental data characterizing temperature-dependent changes of tissue dielectric properties at 915 MHz, we comparatively assess two temperature dependent approaches of modeling of dielectric properties: model A- piecewise linear temperature dependencies based on existing, but limited, experimental data, and model B- similar to model A, but augmented with linear decrease in electrical conductivity above 95 °C, as guided by our experimental measurements...
May 23, 2017: Medical Physics
https://www.readbyqxmd.com/read/28541910/an-investigation-on-ground-electrodes-of-capacitive-coupling-human-body-communication
#13
Jingna Mao, Huazhong Yang, Bo Zhao
Utilizing the body surface as the signal transmission medium, capacitive coupling human body communication (CC-HBC) can achieve a much higher energy efficiency than conventional wireless communications in future wireless body area network (WBAN) applications. Under the CC-HBC scheme, the body surface serves as the forward signal path, whereas the backward path is formed by the capacitive coupling between the ground electrodes (GEs) of transmitter (TX) and receiver (RX). So the type of communication benefits from a low forward loss, while the backward loss depending on the GE coupling strength dominates the total transmission loss...
May 24, 2017: IEEE Transactions on Biomedical Circuits and Systems
https://www.readbyqxmd.com/read/28541192/real-time-error-control-for-surgical-simulation
#14
Huu Phuoc Bui, Satyendra Tomar, Hadrien Courtecuisse, Stephane Cotin, Stephane Bordas
OBJECTIVE: To present the first real-time a posteriori error-driven adaptive finite element approach for realtime simulation and to demonstrate the method on a needle insertion problem. METHODS: We use corotational elasticity and a frictional needle/tissue interaction model. The problem is solved using finite elements within SOFA1. The refinement strategy relies upon a hexahedron-based finite element method, combined with a posteriori error estimation driven local h-refinement, for simulating soft tissue deformation...
May 23, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28538996/the-relationship-between-surface-curvature-and-abdominal-aortic-aneurysm-wall-stress
#15
Sergio Ruiz de Galarreta, Aitor Cazon, Raúl Antón, Ender A Finol
The maximum diameter criterion is the most important factor when predicting risk of rupture of abdominal aortic aneurysms (AAA). An elevated wall stress has also been linked to a high risk of aneurysm rupture, yet is an uncommon clinical practice to compute AAA wall stress. The purpose of this study is to assess whether other characteristics of the AAA geometry are statistically correlated with wall stress. Using in-house segmentation and meshing algorithms, thirty patient-specific AAA models were generated for finite element analysis...
May 24, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28538985/numerical-approximation-of-elasticity-tensor-associated-with-green-naghdi-rate
#16
Haofei Liu, Wei Sun
Objective stress rates are often used in commercial finite element (FE) programs. However, deriving a consistent tangent modulus tensor (also known as elasticity tensor or material Jacobian) associated with the objective stress rates is challenging when complex material models are utilized. In this paper, an approximation method for the tangent modulus tensor associated with the Green-Naghdi rate of the Kirchhoff stress is employed to simplify the evaluation process. The effectiveness of the approach is demonstrated through the implementation of two user-defined fiber-reinforced hyperelastic material models...
May 24, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28538668/biomechanical-modeling-of-pterygium-radiation-surgery-a-retrospective-case-study
#17
Bojan Pajic, Daniel M Aebersold, Andreas Eggspuehler, Frederik R Theler, Harald P Studer
Pterygium is a vascularized, invasive transformation on the anterior corneal surface that can be treated by Strontium-/Yttrium90 beta irradiation. Finite element modeling was used to analyze the biomechanical effects governing the treatment, and to help understand clinically observed changes in corneal astigmatism. Results suggested that irradiation-induced pulling forces on the anterior corneal surface can cause astigmatism, as well as central corneal flattening. Finite element modeling of corneal biomechanics closely predicted the postoperative corneal surface (astigmatism error -0...
May 24, 2017: Sensors
https://www.readbyqxmd.com/read/28538593/dynamic-response-of-the-lumbar-spine-to-whole-body-vibration-under-a-compressive-follower-preload
#18
Li-Xin Guo, Wei Fan
STUDY DESIGN: A finite element study of dynamic response of the lumbar spine to whole-body vibration. OBJECTIVE: To develop and validate a finite element model for exploring the impact of whole-body vibration on the entire lumbar spine with a compressive follower preload applied. SUMMARY OF BACKGROUND DATA: Several finite element studies have investigated the biodynamic characteristics of the human lumbar spine when exposed to whole-body vibration...
May 22, 2017: Spine
https://www.readbyqxmd.com/read/28536892/patient-specific-stress-analyses-in-the-ascending-thoracic-aorta-using-a-finite-element-implementation-of-the-constrained-mixture-theory
#19
S Jamaleddin Mousavi, Stéphane Avril
It is now a rather common approach to perform patient-specific stress analyses of arterial walls using finite-element models reconstructed from gated medical images. However, this requires to compute for every Gauss point the deformation gradient between the current configuration and a stress-free reference configuration. It is technically difficult to define such a reference configuration, and there is actually no guarantee that a stress-free configuration is physically attainable due to the presence of internal stresses in unloaded soft tissues...
May 23, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28536534/a-bio-realistic-finite-element-model-to-evaluate-the-effect-of-masticatory-loadings-on-mouse-mandible-related-tissues
#20
Alexander Tsouknidas, Lucia Jimenez-Rojo, Evangelos Karatsis, Nikolaos Michailidis, Thimios A Mitsiadis
Mice are arguably the dominant model organisms for studies investigating the effect of genetic traits on the pathways to mammalian skull and teeth development, thus being integral in exploring craniofacial and dental evolution. The aim of this study is to analyse the functional significance of masticatory loads on the mouse mandible and identify critical stress accumulations that could trigger phenotypic and/or growth alterations in mandible-related structures. To achieve this, a 3D model of mouse skulls was reconstructed based on Micro Computed Tomography measurements...
2017: Frontiers in Physiology
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