National Repository of Grey Literature 13 records found  previous11 - 13  jump to record: Search took 0.01 seconds. 
Modelling and Optimization of Complex Fiber Diffractive Structures
Helán, Radek ; Lazar,, Josef (referee) ; Tománek, Pavel (referee) ; Urban, František (advisor)
The thesis discusses the fiber Bragg gratings simulations, analysis and design. In the present time, there are several methods to simulate fiber gratings response based on the stated parameters that define their dimensions and material features. However, this work deals with a different issue, that is the synthesis of the input parameters for demanded spectral responses. The main aim of the work is to achieve a synthesis method that would help to discover parameters describing advanced grating structure, based on the required spectral reflectivity. The basic demand for the parameter synthesis is an achievement of the real values in terms of the consequent production of the suggested structure. The described synthesis method considers advanced fiber grating structure as a structure of several uniform grating sections. The input parameters are estimated in steps, using the well-known direct methods in order to obtain grating responses and feedback to establish the parameters changes. The principle methods involve establishment of initial input parameter values and necessary subsequent algorithm leading to optimize the required spectral response. The initial values are calculated by a simplified model based on the coupled theory equations that are handled for the periodic disturbances in cylindrical waveguide. The following optimization uses the multiple thin film stack and transfer matrix methods. The properties of grating structure spectral reflectivity are step by step calculated while using these direct methods. Input parameters are established in the next several steps. Establishment of input parameters is done subsequently, based on the demanded and calculated output spectral reflectivity properties. Optimizing process is limited by possibilities of the grating manufacture technology. It is possible to assemble arbitrary fiber grating structure taking in term the demanded spectral response. Nevertheless, the calculated input parameters are real for the following manufacture. This method could be used to design optical band stop filter, high-pass and low-pass filters or filters for special applications.
Programme for calculation of electric machine shaft deflection caused by magnetic traction
Kukačka, Radek ; Lošák, Petr (referee) ; Vlach, Radek (advisor)
This Master thesis desires the design of methodology for calculating shaft deflection and critical speed of electric machines. There are two methods used. The first one is transfer matrix method, which is represented by a simple programme for shaft creation and calculating needed results built in the Matlab software. The second one is finite element method, which is presented in the Ansys Workbench software.
1D modeling of the influence of velopharyngeal insufficiency on phonation of vowels
Radolf, Vojtěch ; Vampola, T.
Velopharyngeal insufficiency is modeled in frequency domain by the transfer matrix method in connection with conical acoustical elements. The vocal tract is considered as a branched system with two nasal ducts. The influence of viscous losses and radiation impedance both at the level of the lips and at the level of the nostrils are considered. Configuration of the vocal tract corresponds to the vowel /a:/. The modal analysis is performed and the results are compared with those gained from 3D FEM models.

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