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An Electro-Hydrodynamic Model for Bioimpedance Plethysmography
Vyroubal, Petr ; Uruba,, Václav (referee) ; Horák,, Vladimír (referee) ; Maxa, Jiří (advisor)
This doctoral thesis deals with the study of electro-hydrodynamics in the area of numerical modelling of biomechanical systems, concretely in the method of bioimpedance plethysmography. Solving tasks of pulsatile blood flow in the elastic vessel wall is currently one of the most complicated problem in mechanics and biomechanics due to the interaction of two continua on the common boundary. The whole system is additionally loaded by diagnostic electric current. This doctoral thesis was created in cooperation with the Institute of Scientific Instruments of the CAS, v. v. i. Brno with the team engaged in medical signals (the leader Ing. Pavel Jurák, CSc.). Experimental measurements were made independently in the St. Anne's University Hospital Brno in the International Clinical Research Center ICRC and in the Mayo Clinic USA.
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Electro-Magneto-Hydrodynamic Model for Electron Microscopy
Mačák, Martin ; Horák, Vladimír (referee) ; Uruba, Václav (referee) ; Vyroubal, Petr (advisor)
This dissertation thesis deals with the description and development of an electromagneto-hydrodynamic model intended for electron microscopy. The basis of the work lies in the description of characteristic phenomena taking place in electron microscopes with a focus on environmental electron microscopy. The work dealt with a description of the electromagnetic field, supersonic flow of rarefied gas and a motion of relativistic charged particles in a gaseous environment. An electromagnetic model based on the definition of electric and magnetic vector potential was presented and was used for a simulation of an electromagnetic coil. The supersonic flow of a rarefied gas was defined by Navier-Stokes equations. In order to extend their application to low pressures, the boundary conditions for velocity and temperature were modified. Viscosity and thermal conductivity were subsequently introduced as functions of gas pressure. These adjustments were able to describe the effects of lower collision frequency of gas particles. The presented model was used for the analysis of a flow through a separate aperture and a differentially pumped chamber. Furthermore, the model and necessary adjustments for the description of relativistically moving particles were presented. The model was used for the simulation of electron optics. Separate attention was paid to the interaction of charged particles with a gaseous environment. These interactions had a stochastic character and the presented model described both elastic and inelastic collisions. The presented multiphysics model enables the simultaneous simulation of different physical areas and the interactions between them, which leads to a possibility of a more detailed description of processes and to the improvement of environmental electron microscope design.
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An Electro-Hydrodynamic Model for Bioimpedance Plethysmography
Vyroubal, Petr ; Uruba,, Václav (referee) ; Horák,, Vladimír (referee) ; Maxa, Jiří (advisor)
This doctoral thesis deals with the study of electro-hydrodynamics in the area of numerical modelling of biomechanical systems, concretely in the method of bioimpedance plethysmography. Solving tasks of pulsatile blood flow in the elastic vessel wall is currently one of the most complicated problem in mechanics and biomechanics due to the interaction of two continua on the common boundary. The whole system is additionally loaded by diagnostic electric current. This doctoral thesis was created in cooperation with the Institute of Scientific Instruments of the CAS, v. v. i. Brno with the team engaged in medical signals (the leader Ing. Pavel Jurák, CSc.). Experimental measurements were made independently in the St. Anne's University Hospital Brno in the International Clinical Research Center ICRC and in the Mayo Clinic USA.
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