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Raman assembly for radiation analysis
Stránská, Lenka ; Ježek, Jan (referee) ; Dostál, Zbyněk (advisor)
For Raman spectroscopy is a need to introduce a laser light into an optic fiber and analyze a collected light at the same time. Therefore it was proposed a specialized optical system. This system can also be used to measure other spectroscopy methods such as photoluminescence. In the theoretical part of this theses, was discussed both mentioned methods and their instrumentations. In addition to the Raman spectroscopy, was also shown some special cases of Raman spectroscopy for enhanced measurement of Raman scattering. The problem of weak signal detection and its reading is also discussed in the theoretical part of the thesis. In the practical part of this thesis was discussed the mechanical design of the optical system and the choice of optical elements that are used in the system. Next, is introduced the manufactured system, which design is based on the parameters of the chosen optical elements. The practical part of the thesis ends with an assembly and testing of the proposed system.
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Home Automation Based on Arduino/WeMos/RPi Platform
Ježek, Jan ; Špaňhel, Jakub (referee) ; Kapinus, Michal (advisor)
This work aims to propose and implement a home automation system based on individual devices' connection using conditions and actions. For example, when a magnetic barrier determines that a door was opened, a command that turns on lights in the hallway is sent. However, if a card reader does not register allowed card, the alarm will be triggered. This problem is solved by a server running on Raspberry Pi, which is periodically checking all conditions that a user has defined via a web page. Based on their fulfillment, it executes predefined action. Created solution provides a way how to connect smart devices in household easily and how to automate them. Users must program each module, complex conditions, and actions by themselves. This work presents an infrastructure for communication and examples on how to create such modules.
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Exchange Rate Volatility and Trade: Trade in Intermediates versus Trade in Final Products
Ježek, Jan ; Semerák, Vilém (advisor) ; Cazachevici, Alina (referee)
This work represents an attempt to observe exchange rate volatility impact on international trade flows decomposed into intermediates and final products. Existing production chains are costly and sometimes risky to relocate. This thesis aims to test that belief and further, tests assumption that demand for final products is more elastic with respect to foreign exchange rate volatility than that with intermediates. It uses data from 2000 to 2014 and employs gravity model of trade on the sample of 43 countries. Country pair Fixed effects and Bonus Vetus OLS are then used as method of estimation. This work emphasizes proper theory-consistent estimation. It stays in line with contemporary empirical literature only a small negative overall effect is estimated. I find that when foreign exchange rate volatility grows by 10% trade is reduced by less than 0,5%. Regarding expected difference in effect of elasticities I however remain inconclusive.
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Imaging via multimode optical fiber: recovery of a transmission matrix using internal references
Šiler, Martin ; Jákl, Petr ; Traegaardh, Johanna ; Ježek, Jan ; Uhlířová, Hana ; Tučková, Tereza ; Zemánek, Pavel ; Čižmár, Tomáš
Current research of life shows a great desire to study the mechanics of biological processes\ndirectly within the complexity of living organisms. However, majority of practical techniques\nused nowadays for tissue visualization can only reach depths of a few tens of micrometres as\nthe issue obscures deep imaging due to the random light scattering. Several imaging\ntechniques deal with this problems from different angels, such as optical coherence\ntomography, light sheet microscopy or structured light illumination A different and promising strategy to overcome the turbid nature of scattering tissues is to employ multimode optical fibers (MMF) as minimally invasive light guides or endoscopes to provide optical access inside. Although the theoretical description of light propagation through such fibers has been developed a long time ago it is frequently considered inadequate to describe real MMF. The inherent randomization of light propagating through MMFs is typically attributed to undetectable deviations from the ideal fiber structure. It is a commonly believed that this\nadditional chaos is unpredictable and that its influence grows with the length of the fiber.\nDespite this, light transport through MMFs remains deterministic and can be characterized by a transmission matrix (TM) which connects the intensity and phase patterns on the fiber input and output facets. Once the TM is known it can be used to create focus in any desired 3D\ncoordinates beyond the distal fiber facet, see figure 1, and perform e.g. fluorescence based\nlaser scanning microscopy or optical trapping.
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Optical binding of polystyrene particles in tractor beam
Damková, Jana ; Chvátal, Lukáš ; Oulehla, Jindřich ; Ježek, Jan ; Brzobohatý, Oto ; Zemánek, Pavel
The motion of a particle illuminated by a laser beam is usually driven by the photon flow due\nto the radiation pressure and therefore for particle trapping, one has to employ gradient forces. But in a tractor beam, objects are illuminated by the uniform light intensity and even so they can be pulled against the beam propagation. There have been developed several techniques how to create such a tractor beam. In our case, the tractor beam is created by two identical Gaussian beams that interfere under the defined angle. It creates the\nstanding wave, where in the transversal plane the particle is trapped by means of the gradient\nforce, but in the total beam propagation direction, the particle manipulation is driven by the non-conservative force. It is remarkable that this force can for the specific combinations of\nparameters pull the micro-particle against the beam propagation. This kind of behavior is\nbecause of the particle scattering where the majority of the incident photons is scattered in the forward direction and, based on the principle of action and reaction, the transfer of\nmomentum leads to a backward movement of the object. The pushing and pulling force is\nsensitive to the polarization of the laser beam, its incident angle and the particle size so this\ntechnique can be used for example for sorting of objects of different sizes.
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Experimental fluorescence device for dielectrophoretic sorting of droplets in microfluidic chips
Ježek, Jan ; Pilát, Zdeněk ; Šmatlo, Filip ; Zemánek, Pavel
At present, many chemical and biological disciplines use different forms of spectroscopy for their observations. One of the most common methods is fluorescence spectroscopy. During the last seven years, microfluidic techniques began developing rapidly, using channels in which two immiscible liquids create droplets with diameters from units to tens to hundreds of micrometers. These droplets serve as liquid microcontainers containing the analysed sample and the necessary reagents. Using special microfluidic techniques, it is possible to fuse droplets with different contents (controlled triggering of chemical reactions), to change the concentration of reactants in the droplet with high speed (concentration gradients), or sort the droplets by content (creation of new cell strains).\n\n
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