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Oscillatory Power Generator Base on Mechanical Resonant Element
Mihalík, Vlastimil ; Houška, Pavel (referee) ; Hadaš, Zdeněk (advisor)
This work deals with the power supply of wireless sensors. When using a wireless sensor is desirable application of alternative energy sources, because the primary cells or batteries may reduce the extent or length of service of the sensor itself. Ambient energy can be used as a suitable alternative source. This energy must be in an appropriate form, which allows its conversion to electric energy. These appropriate, already used types include: solar en., temperature gradient en., en. of flowing liquids, vibration, etc. The advantage of vibrations is its presence in almost all mechanical systems. One of the possibilities for using the vibration of machine systems for power supply wireless sensors is using the vibration power generator with oscillating component. The generator must be designed so that its resonance frequency coincides with the frequency of vibration in the machine system. This method can be used only if the machinery system vibrations at least partially constant. Another option is to use the vibrations caused by, for example, transit transport, or different step acting factor. In this case, it is desirable that the generator is designed with variable resonant frequency, which can partly be achieved, for example, integrating several oscillating component in the body of generator. After the general analysis of the problem, graduation theses will be concerned with the possibility of use of energy from the short damped oscillation and step impulse. Focusing on a proposal of multi-element structures.
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Unit for wireless transmission of electrical energy
Jelínek, Aleš ; Kopečný, Lukáš (referee) ; Žalud, Luděk (advisor)
The aim of this work is to prove the practical applicability of the concept of contactless energy transfer using induction coils. The first part deals with the mathematical model and theoretical proof of the concept being able to work in practice and describes the process of detecting resonance of receiver circuit on transmitter side. Next chapter describes hardware solution of the experimental prototype. The last part contains measurement results of a coupling coefficient of coils and discusses performance and notable features of the prototype.
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Wireless transfer of energy
Varga, David ; Koňas, Petr (referee) ; Steinbauer, Miloslav (advisor)
ork tie together on first project, in which the was designed apparatus for tests wireless transmission energy. Antenna was synthesized and theoretically optimized for experimental operation, in which the will performed series measuring. In first part is practical description of realization proposal. It consists of circuital solution, proposal measuring workplace and mechanical construction with illustration photographs of arrangement. Second part includes results of performed measuring. These measuring will divided by three basic groups: in first group will by testing feature one’s antennae, in second group will series transmission measuring power gain, and in third group will photographed shape of field, and comparison with simple simulation finite difference method. Third part summarises results from measuring, and prepares consecutive balancing visualisation project, which is of thematic bent on chosen aspects theoretical hypothesis and effected experiments.
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Redesign of Vibration Power Generator with Respect to Overall Volume and Weight
Vaněček, Michal ; Dušek, Daniel (referee) ; Hadaš, Zdeněk (advisor)
This work deals with improvement construction already of the vibration power generator design. The improvement his feature and search ideal construction with reference to material, proportions and power. Gain here mechanical properties, to come to what best tune up and development of new construction for improved check out characteristics as is achievement. Tuning up of correct parameters proceed by the simulation and modelling in ANSYS and MATLAB environment.
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Maximization of integral outlet quantities of an axisymmetric synthetic jet actuator based on a loudspeaker
Kordík, Jozef ; Trávníček, Zdeněk
The goal of this paper is to find an optimal nozzle size of an axisymmetric synthetic jet actuator based on a loudspeaker. The desirable maximized output quantities are: volumetric flow, momentum flux, and kinetic energy flux. To evaluate these quantities velocity profiles were measured using a hot-wire probe at the actuator nozzle exit. Six different nozzle diameters and three supplied real power levels were tested to find the maxima of the quantities. The actuator operated always at resonance during experiments. It was found out that the momentum flux and the kinetic energy flux reach distinguishable local maxima at particular diameters of the nozzle. Besides, the maxima of the particular quantities do not coincide and the best nozzle size slightly increases with the supplied real power to the actuator.
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Study of additional parametric excitation on reduction of forced resonance vibrations
Šulc, Petr ; Pešek, Luděk
This contribution deals with active reduction of unacceptable vibrations by means of parametric excitation fulfilling certain conditions. It is studied on the case of 2DOF system with additional parametric excitation under harmonic force excitation. On the contrary to the selfexcited vibrations or parametric resonances, the parametric excitation of the forced resonance vibrations of the studied system leads to suppression of the resonance not by "damping" but "splitting" effect.
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Rezonanční chování kulového kyvadlového tlumiče
Fischer, Cyril ; Náprstek, Jiří
The pendulum damper modelled as a two degree of freedom strongly non-linear auto-parametric system is investigated using two approximate differential systems. Uni-directional harmonic external excitation at the suspension point is considered. Semi-trivial solutions and their stability are analyzed. The thorough analysis of the non-linear system using less simplification than it is used in the previous paper is performed. Both approaches are compared and conclusions are drawn.
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Theory and qvantitative evaluation of substituent effects
Exner, Otto
Some classical problems of the theory of substituent effects were solved in terms of isodesmic reactions when they were based on the properties of isolated molecules instead of on the reactivities in solution. Inductive effect, resonance or steric effect of ortho-substituents were evaluated in this way.
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