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Evaluation of a switching device behaviour during short-circuit current
Fendrych, Martin ; Dostál, Lukáš (referee) ; Valenta, Jiří (advisor)
At work, I focused on the principle of electric arc extinction in low voltage devices. I particularly focused on the issue of magnetic switches. Next, I processed by the theory site issue of contact system in magnetic switches. In the practical part of my work, I was testing modular low voltage circuit breaker type of 2B and 10B. Testing was carried out in the laboratory of switchgear. I observed the movement of the contact and electric arc, which was burned between them and conductor wall. Observation was recorded by using a high-speed camera and an oscilloscope. Of acquired waveforms, I evaluated the dynamics of contacts, electric arc length and the value of the arc voltage for different moments.
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Simulation of circuit breaker maglatch dynamic behaviour
Konšel, Ladislav ; Dostál, Lukáš (referee) ; Valenta, Jiří (advisor)
This work includes the theory of circuit breaker construction and is focused mainly on overload function. It mainly deals with electronic circuit breakers, i.e. equipped with an electronic trip unit. The work is focused on the part of trip unit - maglatch of trip unit. For the purposes of simulation, the geometric model is created. Maxwell program is used for the simulation. The work describes the options for conditions input which are necessary for simulation. Using the distribution of magnetic field intensity and magnetic flux density in the section of trip unit maglatch is determined by the simulation. Furthermore, the force effects acting on the armature of the maglatch are calculated. Force values and the directions acting on the armature are determined by changing the simulation parameters - shift of the armature and coil current. Simulations are performed both for steady-state and for dynamic simulation – movement of armature is taken into account. The supply source for the maglatch is created by an external circuit.
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Tyre Mathematical Models
Rubíček, Pavel ; Blaťák, Ondřej (referee) ; Hejtmánek, Petr (advisor)
Today the tire is an integral part of the vehicle. During its development is used in various methods. This publication deals with some of them. In her research is necessary to know its features and design solutions. Basic tire structure is described in the first part. These findings are then fit to the other chapters. In the second part there are examples of several tire models in the form of mathematical equations. These equations are used to determine the force and moment loads acting on the tire. The resulting load may aid in the design of new types of tires. The last part describes how to use mathematical models to calculate and here are other methods how else can it gets information about the load on the tire. There is a list of organizations that deal with simulations and tests.
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Grapple saw for loading crane
Koumar, Martin ; Pokorný, Přemysl (referee) ; Kašpárek, Jaroslav (advisor)
Aim was create "proposal grapple saw on round timber and sawn wood for loading hydraulic crane" of submitted work. Submission contained these entry conditions: maximum outreach, lifting moment, allowed load at setout 4m, other characteristics according to elect tractor trailer with loading crane those category. Estimate sectional surface grab and proposal basic proportions grapple saw was processed at first. Model was solved of grapple saw further. Check calculation of part of grapple saw were next step largely and option some components. Detailed assembly drawing was processed of grapple saw, drawings of parts and item list. Option quality materials and their ovenware were effected for individual single parts grapple saw also.
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Stress and strength analysis of the bike frame and compliance assessment at selected construction places.
Prášil, Jiří ; Horníková, Jana (referee) ; Vrbka, Jan (advisor)
Purpose of this work was the realization of stress and strenght analysis of the bike frame with the help of the basic elasticity approach. At first I had to transfer this task from three-dimensional to two-dimensional and also to simplify to fulfill the beam conditions. I also focused on static safety of the construction. This static safety was solved for two loading modes. First one was define as the load, which cyclist can induce, when he is going on the direct road. Second one was defined as the load, which he can induce, when he is going up to the hill. I used for these calculations mathematical software such as Mathcad 14 or Maple 12, but also modeling software especially Autocad for establishing correct dimensions. At the end I checked the stress and strain analysis obtained by the basic elasticity approach with the solution performed making use of the ANSYS software code.
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Strain, stress and strength analysis of the frame construction.
Hrubý, Jaroslav ; Vlk, Miloš (referee) ; Vrbka, Jan (advisor)
This work deals with the stress and strain calculation as well as with the safety evaluation at the plane (2-D) frame loaded by the individual force F. The aim of this work is not acquiring the use of cutting-edge computer programs to determine the stress and deformation, but to learn how to use practically the basic calculation methods being taught at the subject Strength of materials to get practical experience with the application of these calculation methods.
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The comparison of physics textbooks for basic schools
BUMBA, Tomáš
The goal of the theses is to determine, which physics textbooks are being used at primary schools, compare these textbooks and analyse the conception and the way various topics are elaborated. Another purpose of the theses is to didactically analyse the theme unit Force in textbooks from various authors and to create a new textbook based on the results and knowledge gained during the comparison. The effectiveness of the elaborated textbook was tested in practice. The textbook is designed as a new, practical conception for the tuition of the theme unit Force and should serve as a practical tool, which is even meant to be used for some of the experiments. It is focused on the most realistic aspect of the topic and works with the pupil´s desire to discover and learn new things. The effectiveness was tested didactically in a primary school class and compared with the results of another class, which used usual textbooks and was taught with usual teaching methods. The response of the pupils on the various methods was also of high importance. The results of the testing can be found at the end of the work.
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Strategic Analysis of an Enterprise
Fišarová, Markéta ; Dvořák, Jiří (advisor) ; Kovář, František (referee)
This thesis is aimed at the analysis of external and internal environment in the company Pribina. The aim of the thesis was to make PESTE analysis, Porter's five forces model, Analysis of internal sources and SWOT analysis. The key purpose was to evaluate the current situation and suggest some improvement of these conditions.
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