National Repository of Grey Literature 11 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Field measurement of natural electromagnetic emissions near the active tectonic and mass-movement fractures in caves
Trčka, T. ; Macků, R. ; Koktavý, P. ; Škarvada, P. ; Baroň, I. ; Stemberk, Josef
Laboratory tests on a wide range of solid materials shoved that the electromagnetic emission (EME) signals are generated during the samples mechanical stress. EME anomalies have been observed also under natural conditions in association to fracture processes, tectonic loading, stress redistribution and crack propagation prior to earthquake or in relation to deep-seated gravitational mass movements. This paper describes a first prototype of the Emission data logger, which was specially developed for the continual EME monitoring in field conditions. Our equipment has been installed and tested in Obir Caves (Austria) at an active tectonic fault. The pilot long-term EME measurement results from this location are also presented in this paper.
Analysis of Fluctuation Processes of Solar Cells
Macků, Robert ; Chobola, Zdeněk (referee) ; Franc,, Jan (referee) ; Koktavý, Pavel (advisor)
The thesis deals issue of the silicon solar cells non-destructive testing. The manufacturing technology of solar cells currently features a very high level of perfection. Its further development appears to be limited by amongst other issues imperfect diagnostic methods. The objective of presented research consists in non-destructive studies of processes that influence specimen life and reliability. To this end, I will employ mainly noise based analytical methods in connection with observation of defect optical activities, capacitance measurement etc. These methods are closely related to some specimen bulk imperfections, crystal-lattice defect induced traps, local-stress-subjected regions and, finally, breakdowns, which might bring about specimen destruction. Based on a detailed study and understanding of transport processes, regions in which noise is generated can be identified and appropriate technological measures can be proposed and adopted. Presented research focuses, first of all, on the real solar cell structures, which are inhomogeneous in their nature and are difficult to diagnose. The significant part of this study is attend to the random n-level (in most case just two-level) impulse noise, usually referred to as microplasma noise. This noise is a consequence of local breakdowns in micro-sized regions and brings about reduction of lifetime or destruction of the pn junction. The micro-sized regions have been studied separately by electrical and optical methods and defect properties have been put forward. Nevertheless, no less significant part of the thesis is devoted to the fluctuation modeling of the bulk imperfections in the semi-analytical form.
Solar cell non-destructive analysis
Černý, Michal ; Škarvada, Pavel (referee) ; Macků, Robert (advisor)
This thesis briefly analyse contemporary situation of photovoltaic systems and their actual developemenet. It shows a typical properties of most produced up-to-date types. Decision point of this thesis consist in nondestructive analyse of monocristalic unijunction solar cells. It describes two main diagnostic aproaches. First – through the use of measuring of VA characteristics, second – through the use of measuring noise characteristics. With selected samples are performed experimental measurements and estabilished basic parameters. In case of drone analysis considerably attention is devoted to experimental equipment for automatized measuring of spectral power density. This experimental equipment is consequently used for measuring some samples where we can observe microplazmatic noise.
Analysis of solar cell surface features
Lipr, Tomáš ; Macků, Robert (referee) ; Škarvada, Pavel (advisor)
This thesis is focused on the study of electrical and optical properties of solar cell samples using the near field optical microscope. Process of the image formation is described. Artefacts which are presented on some of topography images are described, too. There are some timing problems with measuring of the sample local electric response. If the measuring and scanning devices are not in the time synchronization there will be some difficulties with measured data representation and 2D image offline formation. Created electronic for SNOM and measuring devices synchronization is presented.
Controlled light source
Pazderský, Tomáš ; Macků, Robert (referee) ; Škarvada, Pavel (advisor)
The aim of the Master´s thesis is proposing and implementation of computer controlled optical radiation source. The theoretical part describes the photometric, the radiometric quantities, applied components such as LED, the microcontroller and possible methods for the LED brightness control. The development of the device is described from the selection of the individual LEDs to the end of the device assembling and programing. On the several LEDs were made properties measurement. A circuit with microcontroller was designed and then was fabricated. The device was programmed for communication and control from the PC. The entire electronic is fitted in the metal frame of the construction box and finally the device functionality is tested.
Quantum efficiency measurement of optoelectronic components and development of experimental equipment
Lipr, Tomáš ; Palai-Dany, Tomáš (referee) ; Macků, Robert (advisor)
This thesis deals with the issue of quantum efficiency measurement of optoelectronic devices. The physical nature of silicon solar cells is explained here. In addition, the quantum efficiency as a concept is introduced. There is also discussed the influence of a solar cell semiconductor structure on the quantum efficiency itself. Furthermore, the thesis is focused on the design of an experimental set-up for automated measurement and data acquisition. The final realization of the step motor control unit is described in detail. It includes local and/or remote operations, design and development motivation. The next chapter is dedicated to analysis of the Matlab source code for remote operation, data acquisition and presentation. The final part of the thesis gives attention to experiments with real structures, not only the solar cells. The obtained results of analyzed measurements are presented at the conclusion.
Design of thermal system for accurate temperature stabilization using Peltier thermoelectric modules
Motl, Jakub ; Trčka, Tomáš (referee) ; Macků, Robert (advisor)
This master’s thesis describes design procedure of a heat-regulating system to stabilize its temperature using a Peltier module. The implementation uses eight-bit microcontroller ATmega16 made by company ATMEL for the local and remote control system. The temperature sensors communicate with the microcontroller by serial SPI interface. To display user data, it has a DEM16217SYH type character LCD display with HD44780 control circuit. To collect data from the cooling areas of Peltier module, accurate ADT7320 temperature sensors are used, made by company Analog Devices. The Control of the Peltier module happens in two points of the electrode system and a bistable hysteresis software regulator is used. The first part summarizes the theory, which concerns with the design. Next part concerned with issues of the Peltier module, overview of temperature sensors, description of the microcontroller, the display unit and the used regulator. Last part describes the hardware and software implementation.
Application of radiation emitted from local areas of PN junction for solar cell diagnostics
Krčál, Ondřej ; Raška, Michal (referee) ; Macků, Robert (advisor)
The microplasma discharges in the PN junction local defect micro-regions are as a rule, accompanied by the emission of light. This radiation from solar cell PN junctions was measured by means of a optical fibre connected to the optical input of a photomultiplier. By inching the fibre by means of computercontrolled X-Y plotter above the cell surface a 2-D image of the irradiation local regions has been created. It is seen that a cell of a superficial area of 100 square cm contains a large number of defects, which depends on applied reverse voltage. This method can be a convenient tool for study and diagnostics of optoelectronic devices.
Noise diagnostic of solar cells
Krahulec, Martin ; Macků, Robert (referee) ; Sadovský, Petr (advisor)
The thesis deals with detailed theoretical and experimental investigation of noise and transport characteristics of selected photovoltaic cells in both forward and reversed directions focusing on the area of local PN junction instability (within the microplasma regions). It will be studied the correlation among different characteristics.
Noise diagnostics of rectifier diodes PN junctions
Klimíček, Jaromír ; Macků, Robert (referee) ; Raška, Michal (advisor)
The thesis deals with the design of the measurement installation, which is intended for the microplasma noise measurements. This noise is being generated in the defective parts of the PN junction. The goal of this work is to design the measurement installation and to realize the fully functional workbench for the analogical noise related measurements and to determine the transfer function of the measurement installation. Main part of the work is to choose proper parameters for the measuring devices and to design the software intended for the automated measurements. Consequently, we have to process the measured waveforms of the microplasma noise, to determine the dependency of the noise on the signal magnitude and to calculate the power spectral noise density. Finally, we have to determine the transfer function of the measurement installation and to design the inversion filter.

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1 MACKŮ, Richard
1 Macků, Robert
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