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Influence of linear and nonlinear damping on the stability of motion of kinematic pairs of gears
Hortel, Milan ; Škuderová, Alena
The damping of dynamic phenomena in the structural complicated mechanical systems with different i.e. rigid or liquid substances of elements is the matter till this time generally recondite. The contribution deals therefore both qualitative and quantitative with the model of different combinations of linear and nonlinear - quadratic and cubic - damping both in the phase of normal gear mesh and in the phase of dynamic tuning when happens to contact bounces of tooth faces in gear mesh and to following contacts with impacts.
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Porovnání numerické simulace tlaku na povrchu třepetajícího se profilu s experimentem v aerodynamickém tunelu
Horáček, Jaromír ; Sváček, Petr ; Vlček, Václav ; Feistauer, M.
The paper compares original experimental results with numerical solution of a 2D aeroelastic problem. The incompressible turbulent flow over a freely vibrating airfoil, with two degrees of freedom for rotation and translation with large vibration amplitudes, is described by the Reynolds averaged Navier Stokes (RANS) equations written in Arbitrary Lagrangian-Eulerian (ALE) form. The Spalart-Allmaras turbulence model is used and the flow is solved by the stabilized FEM. The numerical results are compared with the optical measurements of flow field araund a fluttering doublecircular arc (DCA) 18% profile elastcally supported in a subsonic wind tunnel. The interferometry method was used for airflow visualization in different phases of the profile motion. The numerical resulults for the pressure on the profile surface are in good agreement with the measurement.
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Realization of moving aktivity in Kindergarten
DOLEŽALOVÁ, Iva
The dissertation deals with the importance and realization of exercise of nursery-age children in the current way of life, especially in the contemporary nursery school. In the theoretical part there is information about exercise in general, its meaning for the physical and psychical fitness, a brief characteristic of the organs of motion, nervous control of movement, and a brief development of motor control. Then there is description of physical abilities and skills and a characteristic of physical activities in relation with the contemporary nursery-age education. The last part deals with the pulse rate of nursery-age children and their reaction to exercise. The practical part deals with the measurement of the pulse rate of nursery-age children and their reaction to specific forms of the organization of physical activities. In the conclusion there are the results of the research and a recommendation of suitable ways of the realization of physical activities in the nursery school.
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Computing of MT 25 Microtron Dynamic Behavior and Fast Simulation
Krist, Pavel ; Bíla, J. ; Chvátil, David
This paper presents the design of a mathematical model and its fast simulation developed for the setup of the control system of the MT 25 microtron, which is a cyclic electron accelerator. This type of accelerator has been controlled manually until now. The mathematical model is based on calculations of the electron motion in the accelerating cavity and vacuum chamber. The simulation diagram was created in Matlab – Simulink.
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Studie fluidických snímačů rychlosti útku
Tesař, Václav
Measuring the speed of an unsteady axial motion of weft thread in a shuttle-less loom is a a task considered impossible to perform. It was solved by the author using principles based on colliding air jets. Further development and search for other principles described in this contribution was aimed at increasing sensitivity of the contact-less fluidic sensing.
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Experimentální výzkum Magnusovy síly působící na hladkou kouli při vysokých Reynoldsových číslech
Kharlamov, Alexander ; Chára, Zdeněk ; Vlasák, Pavel
The paper describes the results of experimental research dealing with rotating smooth spherical particles moving quasi-steadily in calm water. The motion of the particles was recorded by a digital video camera. The kinematics of the particles motion was analyzed numerically. The dimensionless Magnus force coefficient, the Reynolds number Re and spin parameter Γ (ratio of peripheral sphere velocity and translational velocity) were evaluated from the time series of the particle coordinates and its angle of rotation. The Magnus force was determined as a function of the Reynolds number and spin parameter for 3000 < Re < 42000 and 0.1 < Γ <7. The results were compared with results from literature and overall data were fitted by a simple function valid for 0.5 < Re < 140000 and 0.1 < Γ <10.
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Motor arm control and object weight determination from dynamic motion
Pour, Radek ; Marada, Tomáš (referee) ; Němec, Zdeněk (advisor)
The diploma thesis is a part of the project Intelligent weighting and sorting of goods. The principle of measuring of weight from movement dynamics with derivation calculation relation is detailed described in the first part. The description of used automation means is also in the first part of the diploma thesis. The second part includes design of three adaptive control systems for controlling DC electromotor’s arm, communication principles between programmable logic controllers and designed code of program.
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Studet`s preconceptions about force and motion
Čížková, Dita ; Mandíková, Dana (advisor) ; Kekule, Martina (referee)
The graduation thesis deals with student`s preconceptions about force and motion. The thesis is divided to three sections. The first division picks up the threads of the bachelor thesis. Within this bachelor thesis there was performed a survey of ideas about relation of force and motion with students of the Faculty of Mathematics and Physics of Charles University and secondary schools' students. Results of survey based on a test with six qualitative problems are shown in tables and are commented. The way of processing of the results is closely described. In addition, the survey results are compared with similar studies performed in previous years in Czechoslovakia, mainly they were compared with results of similar research from the years 1981/82 and 1983/84. The survey results show existence of misconceptions, which persist despite school education. The survey of researches in this area is mentioned in the second division. In the third part of the thesis, I focus on the processing of research which was executed in terms of FCI test with the Faculty of Mathematics and Physics of Charles University first year students. The results are shown in tables and are commented again. The results of this research are compared with available results of similar researches from other countries. The individual...
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Local Environment as Hyperlink
Mešár, Marek ; Maršík, Lukáš (referee) ; Beran, Vítězslav (advisor)
Document describes selected techniques and approaches to problem of text detection, extraction and recognition on modern mobile devices. It also describes their proper presentation to the user interface and their conversion to hyperlinks as a source of information about surrounding world. The paper outlines text detection and recognition technique based on MSER detection and also describes the use of image features tracking method for text motion estimation.
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