Determination of Mechanical Stresses in Vibration and Contact During Flow-Structure-Interaction in Vocal Folds

2011 ◽  
Author(s):  
Pinaki Bhattacharya ◽  
Thomas H. Siegmund
Keyword(s):  
Surface Deformation ◽  
Three Dimensional ◽  
Vocal Folds ◽  
Biomechanical Properties ◽  
Mechanical Stresses ◽  
Physical Models ◽  
Tissue Properties ◽  
Transient Nature ◽  
Superior Surface ◽  
Glottal Flow

Mechanical stresses in vocal folds (VFs) developed during self-oscillation — due to interaction with the glottal flow — play an important role in tissue damage and healing. Contact stresses occurring due to collision between VFs modify both self-oscillation characteristics, as well as stresses. The complexity of the problem is increased due to other factors acting in combination: transient nature of the flow, non-linear and anisotropic biomechanical properties of the VFs, and acoustic loading. Experiments with physical models [1] have attempted to deduce the state of stress in the interior through measurement of superior surface deformation. However, these methods pose challenges in data acquisition. on the other hand, full three-dimensional transient computational analysis of a self-oscillating and contacting VF model requires highly sophisticated algorithms as well as prohibitive resource usage. Not surprisingly, therefore, it has not been conducted until now. We hypothesize that a high-fidelity numerical simulation incorporating realistic tissue properties is essential to accurately determine stresses within VFs during self-oscillation and contact.

Characterization of the Biomechanical Properties of the Lower Esophagus for Surgical Simulation

2006 ◽  
Vol 326-328 ◽  
pp. 835-838 ◽  
Author(s):  
Chang Mok Choi ◽  
Hyon Yung Han ◽  
Jung Kim ◽  
Joo No Cheong
Keyword(s):  
Surgical Simulation ◽  
Animal Experiments ◽  
Three Dimensional ◽  
Estimation Algorithm ◽  
Medical Personnel ◽  
Biomechanical Properties ◽  
Fe Model ◽  
Lower Esophagus ◽  
Tissue Properties ◽  
Tissue Model

In this work a method to characterize soft tissue properties for mechanical modeling is presented. Attention is especially focused on developing a model of the lower esophagus to be used in a surgical simulation, which shows a promise as a training method for medical personnel. The viscoelastic properties of the lower esophageal junction are characterized using data from animal experiments and an inverse FE parameter estimation algorithm. Utilizing the assumptions of quasilinear- viscoelastic theory, the viscoelastic and hyperelastic material parameters are estimated to provide a physically based simulation of tissue deformations in real time. To calibrate the parameters to the experimental results, a three dimensional FE model that simulates the forces at the indenter and an optimization program that updates new parameters and runs the simulation iteratively are developed. It was possible to reduce the time and computation resources by decoupling the viscoelastic part and elastic part in a tissue model. The comparison of the simulation and the experimental behavior of pig esophagus are presented to provide validity to the tissue model using the proposed approach.

A Noninvasive System for Biomechanical Properties Measurement of Soft Tissue

2008 ◽  
Vol 2 (3) ◽  
Author(s):  
James Mayrose
Keyword(s):  
Soft Tissue ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Biomechanical Properties ◽  
Medical Professional ◽  
Individual Layer ◽  
Tissue Properties ◽  
Stiffness Properties ◽  
Force Displacement ◽  
Three Dimensional Space

A device for measuring the biomechanical properties of soft tissue via palpation was developed. The device, which is worn by a medical professional, incorporates sensors that collect data on the position of the users’ hand in three-dimensional space as well as the force that the user applies to the tissue. The depth of palpation, the force used to achieve that depth, and the thickness of the tissue obtained from a computed tomography scan of the abdomen were used to calculate the stiffness properties of each individual layer of tissue. Some experimental data obtained by curve fitting force-displacement curves are presented. The data obtained from this experiment illustrates the potential of this device to be used for accurate measurement of soft tissue properties.

A Study of Self-Oscillation of a Model Vocal Fold System by Digital Image Correlation

2006 ◽  
Author(s):  
M. Spencer ◽  
T. Siegmund ◽  
L. Mongeau
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Vocal Fold ◽  
High Speed ◽  
Vocal Folds ◽  
Physical Models ◽  
Image Correlation ◽  
Laser Doppler Velocimeter ◽  
Sustained Oscillation ◽  
Superior Surface

The understanding of the mechanics of the deformation behavior of vocal folds during flow-induced vibration is of central interest in studies of voice production. We have developed physical models of the vocal folds and connected such models to a flow supply system. The self-sustained oscillation of the vocal folds during phonation experiments is investigated using digital image correlation (DIC) techniques enabled through the use of a high-speed digital camera. A laser Doppler velocimeter was used to independently verify results from the DIC. The study reports on vibratory motion of the superior surface of the model vocal folds, and documents strain fields, and principal strains on that surface. From measured strains and the incompressibility assumption, the corresponding stress fields are computed. Strains on the vocal fold superior surface are quantified in dependence of varying subglottal pressures and flow rates.

scholarly journals Three-dimensional deformation time series of glacier motion from multiple-aperture DInSAR observation

2019 ◽  
Vol 93 (12) ◽  
pp. 2651-2660 ◽  
Author(s):  
Sergey Samsonov
Keyword(s):  
Time Series ◽  
Surface Deformation ◽  
Ground Deformation ◽  
Three Dimensional ◽  
Data Sets ◽  
Ice Flow ◽  
The North ◽  
Glacier Ice ◽  
Deformation Component ◽  
3D Deformation

AbstractThe previously presented Multidimensional Small Baseline Subset (MSBAS-2D) technique computes two-dimensional (2D), east and vertical, ground deformation time series from two or more ascending and descending Differential Interferometric Synthetic Aperture Radar (DInSAR) data sets by assuming that the contribution of the north deformation component is negligible. DInSAR data sets can be acquired with different temporal and spatial resolutions, viewing geometries and wavelengths. The MSBAS-2D technique has previously been used for mapping deformation due to mining, urban development, carbon sequestration, permafrost aggradation and pingo growth, and volcanic activities. In the case of glacier ice flow, the north deformation component is often too large to be negligible. Historically, the surface-parallel flow (SPF) constraint was used to compute the static three-dimensional (3D) velocity field at various glaciers. A novel MSBAS-3D technique has been developed for computing 3D deformation time series where the SPF constraint is utilized. This technique is used for mapping 3D deformation at the Barnes Ice Cap, Baffin Island, Nunavut, Canada, during January–March 2015, and the MSBAS-2D and MSBAS-3D solutions are compared. The MSBAS-3D technique can be used for studying glacier ice flow at other glaciers and other surface deformation processes with large north deformation component, such as landslides. The software implementation of MSBAS-3D technique can be downloaded from http://insar.ca/.

The superiority of three-dimensional physical models to two-dimensional computer presentations in anatomy learning

2018 ◽  
Vol 52 (11) ◽  
pp. 1138-1146 ◽  
Author(s):  
Bruce Wainman ◽  
Liliana Wolak ◽  
Giancarlo Pukas ◽  
Eric Zheng ◽  
Geoffrey R Norman
Keyword(s):  
Three Dimensional ◽  
Physical Models ◽  
Two Dimensional

scholarly journals Protein Folding: Search for Basic Physical Models

2003 ◽  
Vol 3 ◽  
pp. 623-635 ◽  
Author(s):  
Ivan Y. Torshin ◽  
Robert W. Harrison
Keyword(s):  
Protein Folding ◽  
Tertiary Structure ◽  
Three Dimensional ◽  
Physical Models ◽  
Dimensional Structure ◽  
Computational Techniques ◽  
Linear Sequence ◽  
Physical Forces

How a unique three-dimensional structure is rapidly formed from the linear sequence of a polypeptide is one of the important questions in contemporary science. Apart from biological context ofin vivoprotein folding (which has been studied only for a few proteins), the roles of the fundamental physical forces in thein vitrofolding remain largely unstudied. Despite a degree of success in using descriptions based on statistical and/or thermodynamic approaches, few of the current models explicitly include more basic physical forces (such as electrostatics and Van Der Waals forces). Moreover, the present-day models rarely take into account that the protein folding is, essentially, a rapid process that produces a highly specific architecture. This review considers several physical models that may provide more direct links between sequence and tertiary structure in terms of the physical forces. In particular, elaboration of such simple models is likely to produce extremely effective computational techniques with value for modern genomics.

scholarly journals Progressive Degradation of an Ice Rumple in the Thwaites Ice Shelf, Antarctica, as Observed from High-Resolution Digital Elevation Models

2018 ◽  
Vol 10 (8) ◽  
pp. 1236 ◽  
Author(s):  
Seung Hee Kim ◽  
Duk-jin Kim ◽  
Hyun-Cheol Kim
Keyword(s):  
High Resolution ◽  
Surface Deformation ◽  
Surface Expression ◽  
Deformation Model ◽  
Ice Shelf ◽  
Pressure Source ◽  
Viscoelastic Deformation ◽  
Shelf Stability ◽  
Transient Nature ◽  
Elevation Changes

Ice rumples are locally-grounded features of flowing ice shelves, elevated tens of meters above the surrounding surface. These features may significantly impact the dynamics of ice-shelf grounding lines, which are strongly related to shelf stability. In this study, we used TanDEM-X data to construct high-resolution DEMs of the Thwaites ice shelf in West Antarctica from 2011 to 2013. We also generated surface deformation maps which allowed us to detect and monitor the elevation changes of an ice rumple that appeared sometime between the observations of a grounding line of the Thwaites glacier using Double-Differential Interferometric SAR (DDInSAR) in 1996 and 2011. The observed degradation of the ice rumple during 2011–2013 may be related to a loss of contact with the underlying bathymetry caused by the thinning of the ice shelf. We subsequently used a viscoelastic deformation model with a finite spherical pressure source to reproduce the surface expression of the ice rumple. Global optimization allowed us to fit the model to the observed deformation map, producing reasonable estimates of the ice thickness at the center of the pressure source. Our conclusion is that combining the use of multiple high-resolution DEMs and the simple viscoelastic deformation model is feasible for observing and understanding the transient nature of small ice rumples, with implications for monitoring ice shelf stability.

Analytical and 3D Finite Element Study of the Deflection of an Elastic Cantilever Bilayer Plate

2010 ◽  
Vol 78 (1) ◽  
Author(s):  
M. Chekchaki ◽  
V. Lazarus ◽  
J. Frelat
Keyword(s):  
Thin Films ◽  
Finite Element ◽  
Three Dimensional ◽  
Analytical Formula ◽  
Mechanical Stresses ◽  
Linear Elastic ◽  
Wide Range ◽  
Finite Element Calculations ◽  
Analytical Formulas ◽  
Three Dimensional Elasticity

The mechanical system considered is a bilayer cantilever plate. The substrate and the film are linear elastic. The film is subjected to isotropic uniform prestresses due for instance to volume variation associated with cooling, heating, or drying. This loading yields deflection of the plate. We recall Stoney’s analytical formula linking the total mechanical stresses to this deflection. We also derive a relationship between the prestresses and the deflection. We relax Stoney’s assumption of very thin films. The analytical formulas are derived by assuming that the stress and curvature states are uniform and biaxial. To quantify the validity of these assumptions, finite element calculations of the three-dimensional elasticity problem are performed for a wide range of plate geometries, Young’s and Poisson’s moduli. One purpose is to help any user of the formulas to estimate their accuracy. In particular, we show that for very thin films, both formulas written either on the total mechanical stresses or on the prestresses, are equivalent and accurate. The error associated with the misfit between our theorical study and numerical results are also presented. For thicker films, the observed deflection is satisfactorily reproduced by the expression involving the prestresses and not the total mechanical stresses.

Finescale Dual-Doppler Analysis of Hurricane Boundary Layer Structures in Hurricane Frances (2004) at Landfall

2014 ◽  
Vol 142 (5) ◽  
pp. 1874-1891 ◽  
Author(s):  
Karen A. Kosiba ◽  
Joshua Wurman
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Transient Nature ◽  
Layer Structures ◽  
Characteristic Wavelength ◽  
Doppler Data ◽  
Mean Wind Speed ◽  
Average Flux ◽  
Hurricane Boundary Layer ◽  
The Right

Abstract Two Doppler on Wheels (DOW) mobile radars collected fine-spatial-scale dual-Doppler data in the right-front quadrant and eye of Hurricane Frances (2004) as it made landfall near Stuart, Florida. A 5.7-km dual-Doppler baseline established a dual-Doppler domain south and east of Fort Pierce, Florida, encompassing a 5.5 km × 5.5 km horizontal area, with a grid spacing of 20 m, allowing for the resolution of subkilometer-scale horizontal structures and associated kinematics. Three-dimensional vector wind analyses of the boundary layer revealed the presence of linear coherent structures with a characteristic wavelength of 400–500 m near the surface that increased in size and became more cellular in shape with increasing height. Average horizontal perturbation winds were proportional to average total horizontal winds. Within the eye of the hurricane, the features lost linear coherency despite a high mean wind speed, possibly due to changes in stability. A slight decrease in the characteristic wavelength of boundary layer structures was documented as the winds cross the barrier islands east of Fort Pierce. Vertical flux of horizontal momentum caused by individual vortical structures was substantially higher than values employed in turbulence parameterization schemes, but the domain-wide average flux was substantially lower than that in individual structures, likely due to the transient nature of the most intense portions of the structures. Analysis of the turbulent kinetic energy (TKE) yielded values comparable to those reported in previous observational studies over the open ocean. However, there was substantial variability in TKE within the dual-Doppler domain, emphasizing the challenge in obtaining representative samples using non-3D measurements such as dropsondes.

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