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Ferroresonance Phenomena in Power Systems
Benda, Tomáš ; Honzák, Aleš (referee) ; Toman, Petr (advisor)
Diploma thesis deals with ferroresonance phenomena which is present in power networks with saturable inductances and capacitors. A distinction drawn between resonance and ferroresonance will highlight the specific. Lack of knowledge means that it is readily considered responsible for a number of unexplained destructions or malfunctionings of equipment. In the work is a description of such behaviours means risk for electrical power systems. Finally, last part presentat produkt by ABB company intend for damping oscillations and summaries measures on it.
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The dynamic characteristics of check valve
Pavlík, Václav ; Dokoupil, Pavel (referee) ; Habán, Vladimír (advisor)
This master´s thesis provides an overview of all designs of check valves, their usage and typical features. Main purpose of this work is to clear up the phenomenon of check valve slam and the other problems that occur during transients. The check valve slam was measured at the test rig in the hydraulic laboratory. For unsteady flow evaluation after pump shut down was used Gibson method. The dynamic characteristic was possible to create by results from this method. It was achieved without impact of the speed of sound in the fluid. This work also contains 2D transient CFD calculations, which was used for evaluation of the hydrodynamic torque acting on the hinge pin. This approach provides an option to calculate wide range of cases at the expense of not entirely exact geometry. The main contribution of the theoretical study at the beginning of this thesis is its entireness. It might give an important clue when right valve is selecting. For good choice of valve might be helpful to use dynamic characteristics in this thesis presented. Mentioned characteristics were created by new way and its background is in measurements and simplified CFD calculations.
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Transitional effects in road vehicle aerodynamics
Kroupa, Michal ; Vančura, Jan (referee) ; Čavoj, Ondřej (advisor)
This bachelor thesis deals with transient phenomena in vehicle aerodynamics with the focus on describing and proposing of unsteady mechanisms. First part investigates transient phenomena during crosswind gusts. Next part deals with unsteady pressure distribution around the vehicle during passing and overtaking manoeuvre. Final part investigates transient phenomena during dynamic pitching motion.
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Segmentations for time-variable systems and their implementation
Pavlíček, Tomáš ; Smékal, Zdeněk (referee) ; Balík, Miroslav (advisor)
This thesis is interested in describing stationary random discrete signals, especially) in music discrete signals. Here is described when is signal stationary and when is not stationary. It contains tip for preprocessing of signal for accurate recognition of local stationarity. Thesis contain mathematical definition of parameters of random digital signals, which are used for stationarity recognition. It is followed by description of basic windows, their categories, describing of their parameters and comparing of each. In next part of thesis are described mothods of segmentations with constant window constant overlap save, constant window constant ovelap add, variable window constant overlap save, variable window constant ovelap add and variable window variable overlap add. It is followed by analyzing of windows used in segmentations with variable lengths of segments. As next point of thesis are transients made by step changes of coefficients of filter in filtering of segments with variable lengths. At the end is investigated the best accurate method of signal stationarity detection. Segments made by accurate method of detection are analyzed. thesis contains exapmle of music signal segmentation.
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The dynamic characteristics of check valve
Pavlík, Václav ; Dokoupil, Pavel (referee) ; Habán, Vladimír (advisor)
This master´s thesis provides an overview of all designs of check valves, their usage and typical features. Main purpose of this work is to clear up the phenomenon of check valve slam and the other problems that occur during transients. The check valve slam was measured at the test rig in the hydraulic laboratory. For unsteady flow evaluation after pump shut down was used Gibson method. The dynamic characteristic was possible to create by results from this method. It was achieved without impact of the speed of sound in the fluid. This work also contains 2D transient CFD calculations, which was used for evaluation of the hydrodynamic torque acting on the hinge pin. This approach provides an option to calculate wide range of cases at the expense of not entirely exact geometry. The main contribution of the theoretical study at the beginning of this thesis is its entireness. It might give an important clue when right valve is selecting. For good choice of valve might be helpful to use dynamic characteristics in this thesis presented. Mentioned characteristics were created by new way and its background is in measurements and simplified CFD calculations.
|
|
|
Segmentations for time-variable systems and their implementation
Pavlíček, Tomáš ; Smékal, Zdeněk (referee) ; Balík, Miroslav (advisor)
This thesis is interested in describing stationary random discrete signals, especially) in music discrete signals. Here is described when is signal stationary and when is not stationary. It contains tip for preprocessing of signal for accurate recognition of local stationarity. Thesis contain mathematical definition of parameters of random digital signals, which are used for stationarity recognition. It is followed by description of basic windows, their categories, describing of their parameters and comparing of each. In next part of thesis are described mothods of segmentations with constant window constant overlap save, constant window constant ovelap add, variable window constant overlap save, variable window constant ovelap add and variable window variable overlap add. It is followed by analyzing of windows used in segmentations with variable lengths of segments. As next point of thesis are transients made by step changes of coefficients of filter in filtering of segments with variable lengths. At the end is investigated the best accurate method of signal stationarity detection. Segments made by accurate method of detection are analyzed. thesis contains exapmle of music signal segmentation.
|
|
|
Ferroresonance Phenomena in Power Systems
Benda, Tomáš ; Honzák, Aleš (referee) ; Toman, Petr (advisor)
Diploma thesis deals with ferroresonance phenomena which is present in power networks with saturable inductances and capacitors. A distinction drawn between resonance and ferroresonance will highlight the specific. Lack of knowledge means that it is readily considered responsible for a number of unexplained destructions or malfunctionings of equipment. In the work is a description of such behaviours means risk for electrical power systems. Finally, last part presentat produkt by ABB company intend for damping oscillations and summaries measures on it.
|
|
|
Transitional effects in road vehicle aerodynamics
Kroupa, Michal ; Vančura, Jan (referee) ; Čavoj, Ondřej (advisor)
This bachelor thesis deals with transient phenomena in vehicle aerodynamics with the focus on describing and proposing of unsteady mechanisms. First part investigates transient phenomena during crosswind gusts. Next part deals with unsteady pressure distribution around the vehicle during passing and overtaking manoeuvre. Final part investigates transient phenomena during dynamic pitching motion.
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