Browsing by Author "Salač, Petr"
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- ItemNumerical evaluation of rheological experiment(Technická univerzita v Liberci, Česká republika, 2012) Salač, Petr; Matoušek, IvoA viscoelastic simply supported rotationally symmetric body, fixed on a base, is considered. The body is loaded by a flat plunger, which moves in the direction of the z axis by a constant velocity v. In this work the reaction force is computed. This allows us to compare numerical results with data from rheological experiment (see [6], [7]). The variational formulation of the problem is derived and transformed to cylindrical coordinates. Some results of numerical calculations are presented.
- ItemNumerical results for the cooling power optimization problem(2018) Salač, PetrThe contribution deals with the numerical results for the cooling power optimization problem for the pressing process in glass forming. The continuous problem was formulated in details at AMEE'17, which focuses to control distribution of temperature on the outward plunger surface. The numerical results were received by the software FreeFem++ version 3.19 for the sample of the real vase made from lead crystal glassware of the height 267 [mm] and the mass 1.55 [kg]. The plunger and the mould were made from steel. The cooling was implemented by the water with the temperature 15 [degrees C] at the entrance. We assume that the water is heated to 100 [degrees C] and changes its state to steam during the cooling. Its weight in the individual parts of the plunger cooling cavity is taken as a design variable. The results of the numerical optimization to the required target temperature 800 [degrees C] of the outward plunger surface together with the distribution of temperatures on the interface between the plunger and the glass before and after the optimization process are presented.
- ItemOptimization of the plunger cooling by the core with high thermal conductivity(AMER INST PHYSICS, 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA, 2019) Salač, PetrThe contribution deals with formulation of the optimization problem for the plunger which is cooled by the metal core with high thermal conductivity in combination with the insulation barrier with low thermal conductivity. The thermal energy is removed from the core to the water cooler and converted into steam there. Shape optimization of the core and the insulation barrier is carried out with the aim of achieving the prescribed constant temperature on the outer surface of the plunger at the time of separation of the plunger and the glass piece. The cost functional is the squared L-r(2) norm of the difference between the prescribed constant and the temperature on the outward boundary of the plunger at time of separation. The existence and uniqueness of the solution to the state problem and the existence of a solution to the shape optimization problem are introduced.
- ItemProblematika vymáhání daňových nedoplatků v České republice(Technická Univerzita v Liberci, 2011) Salač, Petr; Horák, JosefThis diploma thesis deals with the topic of recovery of outstanding tax liabilities in the Czech Republic, whereas it covers description of amendments in the outstanding tax recovery legislation since January 1st, 2011, as this matter is a day-to-day conversation theme of both the public and employees of tax authorities. Statistic methods were used to analyze outstanding tax liabilities and the results of the recovery thereof with the aim to find out the factors affecting the amount of outstanding taxes and identify potential problems. Some problems, such as a delay between the outstanding tax occurrence and the initiation of the recovery process, were discovered. The thesis further contains prediction of the development of cumulative outstanding tax liabilities that may be used from the macroeconomic point of view (state budget incomes).
- ItemShape optimization for a time-dependent model of a carousel press in glass production(ACAD SCIENCES CZECH REPUBLIC, INST MATHEMATICS, ZITNA 25, PRAHA 1, 115 67, CZECH REPUBLIC, 2019) Salač, Petr; Stebel, JanThis contribution presents the shape optimization problem of the plunger cooling cavity for the time dependent model of pressing the glass products. The system of the mould, the glass piece, the plunger and the plunger cavity is considered in four consecutive time intervals during which the plunger moves between 6 glass moulds. The state problem is represented by the steady-state Navier-Stokes equations in the cavity and the doubly periodic energy equation in the whole system, under the assumption of rotational symmetry, supplemented by suitable boundary conditions. The cost functional is defined as the squared weighted L-2 norm of the difference between a prescribed constant and the temperature of the plunger surface layer at the moment before separation of the plunger and the glass piece. The existence and uniqueness of the solution to the state problem and the existence of a solution to the optimization problem are proved.
- ItemSurface Evaluation by Estimation of Fractal Dimension and Statistical Tools(Technická Univerzita v Liberci, 2014) Hotař, Vlastimil; Salač, PetrStructured and complex data can be found in many applications in research and development, and also in industrial practice. We developed a methodology for describing the structured data complexity and applied it in development and industrial practice. The methodology uses fractal dimension together with statistical tools and with software modification is able to analyse data in a form of sequence (signals, surface roughness), 2D images, and dividing lines. The methodology had not been tested for a relatively large collection of data. For this reason, samples with structured surfaces produced with different technologies and properties were measured and evaluated with many types of parameters. The paper intends to analyse data measured by a surface roughness tester. The methodology shown compares standard and nonstandard parameters, searches the optimal parameters for a complete analysis, and specifies the sensitivity to directionality of samples for these types of surfaces. The text presents application of fractal geometry (fractal dimension) for complex surface analysis in combination with standard roughness parameters (statistical tool).