DSpace Kolekce: This issue is co-financed by the European Social Fund and the state budget of the Czech Republic
http://hdl.handle.net/11025/1366
This issue is co-financed by the European Social Fund and the state budget of the Czech RepublicThu, 22 Aug 2019 20:31:14 GMT2019-08-22T20:31:14ZUse of electromyography measurement in human body modeling
http://hdl.handle.net/11025/1966
Název: Use of electromyography measurement in human body modeling
Autoři: Valdmanová, Linda; Čechová, Hana
Abstrakt: The aim of this study is to test the use of the human body model for the muscle activity computation. This
paper shows the comparison of measured and simulated muscle activities. Muscle active states of biceps brachia
muscle are monitored by method called electromyography (EMG) in a given position and for given subsequently
increasing loads. The same conditions are used for simulation using a human body model (Hynˇc´ık, L., Rigid Body
Based Human Model for Crash Test Purposes, EngineeringMechanics, 5 (8) (2001) 1–6). This model consists of
rigid body segments connected by kinematic joints and involves all major muscle bunches. Biceps brachia active
states are evaluated by a special muscle balance solver. Obtained simulation results show the acceptable correlation
with the experimental results. The analysis shows that the validation procedure of muscle activities determination
is usable.Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/11025/19662011-01-01T00:00:00ZValdmanová, LindaČechová, HanaBending of a nonlinear beam reposing on an unilateral foundation
http://hdl.handle.net/11025/1380
Název: Bending of a nonlinear beam reposing on an unilateral foundation
Autoři: Machalová, Jitka; Netuka, Horymír
Abstrakt: This article is going to deal with bending of a nonlinear beam whose mathematical model was proposed by
D. Y. Gao in (Gao, D. Y., Nonlinear elastic beam theory with application in contact problems and variational
approaches,Mech. Research Communication, 23 (1) 1996). The model is based on the Euler-Bernoulli hypothesis
and under assumption of nonzero lateral stress component enables moderately large deflections but with small
strains. This is here extended by the unilateralWinkler foundation. The attribution unilateral means that the foundation
is not connected with the beam. For this problem we demonstrate a mathematical formulation resulting
from its natural decomposition which leads to a saddle-point problem with a proper Lagrangian. Next we are concerned
with methods of solution for our problem by means of the finite element method as the paper (Gao, D. Y.,
Nonlinear elastic beam theory with application in contact problems and variational approaches, Mech. Research
Communication, 23 (1) 1996) has no mention of it. The main alternatives are here the solution of a system of
nonlinear nondifferentiable equations or finding of a saddle point through the use of the augmented Lagrangian
method. This is illustrated by an example in the final part of the article.Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/11025/13802011-01-01T00:00:00ZMachalová, JitkaNetuka, HorymírNumerical analysis of bypass model geometrical parameters influence on pulsatile blood flow
http://hdl.handle.net/11025/1376
Název: Numerical analysis of bypass model geometrical parameters influence on pulsatile blood flow
Autoři: Jonášová, Alena; Vimmr, Jan; Bublík, Ondřej
Abstrakt: The present study is focused on the analysis of pulsatile blood flow in complete idealized 3D bypass models in
dependence on three main geometrical parameters (stenosis degree, junction angle and diameter ratio). Assuming
the blood to be an incompressible Newtonian fluid, the non-linear system of Navier-Stokes equations is integrated
in time by a fully implicit second-order accurate fractional-step method. The space discretization is performed with
the help of the cell-centred finite volume method formulated for unstructured tetrahedral grids. In order to model
a realistic coronary blood flow, a time-dependent flow rate taken from corresponding literature is considered. For
the analysis of obtained numerical results, special emphasis is placed on their comparison in the form of velocity
isolines at several selected cross-sections during systolic and diastolic phases. The remainder of this paper is
devoted to discussion of walls shear stress distribution and its oscillatory character described by the oscillatory
shear index with regard to areas prone to development of intimal hyperplasia or to thrombus formation.Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/11025/13762011-01-01T00:00:00ZJonášová, AlenaVimmr, JanBublík, OndřejAirflow visualization in a model of human glottis near the self-oscillating vocal folds model
http://hdl.handle.net/11025/1375
Název: Airflow visualization in a model of human glottis near the self-oscillating vocal folds model
Autoři: Horáček, Jaromír; Uruba, Václav; Radolf, Vojtěch; Veselý, Jan; Bula, Vítězslav
Abstrakt: The contribution describes PIV (Particle Image Velocimetry) measurement of airflow in the glottal region of complex physical models of the voice production that consist of 1:1 scaled models of the trachea, the self-oscillating vocal folds and the human vocal tract with acoustical spaces that correspond to the vowels /a:/, /u:/ and /i:/. The time-resolved PIV method was used for visualization of the airflow simultaneously with measurements of subglottal pressure, radiated acoustic pressure and vocal fold vibrations. The measurements were performed within a physiologically real range of mean airflow rate and fundamental phonation frequency. The images of the vibrating vocal folds during one oscillation period were recorded by the high-speed camera at the same time instants as the velocity fields measured by the PIV method.
In the region above the model of the ventricular folds and epilarynx tube it is possible to detect large vortices with dimensions comparable with the channel cross-section and moving relatively slowly downstream. The vortices disappear in the narrower pharyngeal part of the vocal tract model where the flow is getting more uniform. The basic features of the coherent structures identified in the laryngeal cavity models in the interval of the measured airflow rates were found qualitatively similar for all three vowels investigated.Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/11025/13752011-01-01T00:00:00ZHoráček, JaromírUruba, VáclavRadolf, VojtěchVeselý, JanBula, Vítězslav