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Identifikace faktorů ovlivňujících spotřebitele při nákupu potravin pod privátní značkou
Hrdlička, Aleš
The thesis deals with the factors that influence consumers when they buy food under a private label. The retail market and private label market is analyzed. The thesis is also devoted to the power of influence of ecological aspects on con-sumers. The ecology affects approximately 50% of consumers. The relationship between socioeconomic characteristics and the volume of purchased food under the private label was demonstrated for the age interval, predominant economic activity and education. A partial goal of the work is also using cluster analysis to segment consumers into similar groups and determining the factors that influence these groups the most. According to that there were created 3 groups of consumers: the ordinary consumers, the environmentalists and the designers.The biggest influence on consumers is the price, the quality, own experience, the availability of the store and domestic origin of the goods. The goal of the work was also suggesting appropriate recommendations for private label food sellers.
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Atomization of hydride forming elements in dielectric barrier plasma discharges
Baranová, Barbora ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
The aim of this diploma thesis was to optimize the atomization conditions of two hydride forming elements - bismuth and tellurium in dielectric barrier discharge (DBD) plasma atomizers using atomic absorption spectrometry (AAS) as a detector. Two types of electrode constructions of planar DBD atomizers were studied: glued and sputtered electrodes while two construction of high voltage power supply sources were investigated employing either a sinusoidal or square wave modulation of high voltage function. The effect of the gas phase dryer included in the apparatus upstream the atomizer was also investigated. A nafion membrane tube dryer was identified as the most effective one. Its efficiency was verified using optical emission spectrometry. With the nafion tube included in the apparatus, two main parameters of DBD atomizers were optimized: the voltage of the power supply source and argon flow rate, which served as a discharge gas. Using optimal conditions, analytical characteristics were determined for all atomizers used and these were subsequently compared with those achieved in an externally heated quartz (multi)atomizer (MM)QTA. In the case of bismuth, the optimal argon flow rate was determined to be 75 cm3 min-1 for all atomizers. The optimal value for the power supply source with sinusoidal...
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Mechanism of atomization of selected hydride forming elements in an externally heated quartz tube atomizer and a dielectric barrier discharge atomizer
Juhászová, Lucie ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Atomization conditions for tin hydride in the planar dielectric barrier discharge (DBD) plasma atomizer were optimized with detection by atomic absorption spectrometry (AAS). The effects of apparatus arrangement such as the shape of a waveform function of the high voltage power supply source, DBD atomizer design as well as presence of a dryer tube filled with NaOH pellets to prevent residual aerosol and moisture transport into the DBD were investigated in detail. The optimal experimental setup consisted of a square wave high voltage power supply source coupled to a DBD with vapor-deposited electrodes in the presence of NaOH dryer upstream the DBD atomizer. Argon was found as the best discharge gas under a flow rate of 120 mL min-1 while the DBD optimum high voltage supply rate was 7 kV. A sensitivity of 0.05 s ng-1 Sn and a limit of detection of 1.1 ng mL-1 Sn were reached under optimized conditions. Optimization of the whole experimental setup resulted in 7-fold improvement of sensitivity compared to the original arrangement consisting of a sinusoidal source coupled to a DBD atomizer with glued electrodes in absence of the dryer. Keywords atomic absorption spectrometry, hydride generation, hydride atomization, quart tube atomizer, dielectric barrier discharge (DBD)
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Next generation of hydride atomizers based on dielectric barrier plasma discharge
Kráľová, Zuzana ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Atomization conditions for selenium and lead hydrides in a dielectric barrier discharge (DBD) plasma atomizer with detection by atomic absorption spectrometry (AAS) were investigated in this work. Two designs of DBD atomizers were studied, the first one with glued electrodes and the second one with sputtered electrodes. The main experimental parameters were optimized, including supplied power and discharge gas (argon) flow rate. Additionally, the effect of several dryers was studied. Analytical figures of merit were determined for both plasma atomizers under the optimized conditions and compared to multiatomizer (MMQTA) as the most common hydride atomizer. The optimum flow rate for selenium determination was 75 cm3 min-1 Ar for both DBD atomizer designs as well as for MMQTA. In case of lead hydride atomization, ideal flow rate of argon was 175 cm3 min-1 for DBD atomizer with glued electrodes and 150 cm3 min-1 with DBD atomizer with sputtered electrodes, while MMQTA required only 100 cm3 min-1 Ar. The optimal power supply for DBD with sputtered electrodes was found significantly lower at 7.3 W for selenium and 13.3 W for lead. A dryer based on nafion membrane was found as the most effective for both analytes studied. Its efficacy was verified by optical emission spectrometry. As for analytical...
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Impact of the atmosphere on laser ablation of matters
Černá, Svatava ; Hrdlička, Aleš (referee) ; Pořízka, Pavel (advisor)
This thesis deals with a general overview of laser-induced breakdown spectroscopy - ablation of material and plasma formation when a change of the surrounding environment occurs. The aim is to establish ideal conditions for improving detection, which is difficult for some elements when the measurement takes place in the ambient atmosphere. This is the reason why we change the ambient conditions, the gas (air, helium, argon) and its pressure. Buffer gases (helium, argon) influence the development of the material ablation and quality of generated plasma. That is why we inspect the changes in the signal according to particular atmospheres (signal change in buffer gases compared to the ambient atmosphere). The first part of the thesis presents the principle and physical nature of laser ablation with a brief search of experiments performed so far for similar purposes. Based on this search we determine conclusions about the influence of buffer gasses and pressure on the detection used gasses. In the second part of the work, the controlled experiment is presented, which consisted of the detection of spectral lines of fluorine and potassium, see chapter 5.6 and molecular transitions of calcium fluoride, see chapter 5.10. In a controlled experiment, we established two assumptions. The first assumption is the influence of the inert gas atmosphere, which should significantly improve the detection of fluorine and potassium compared to the air atmosphere. We confirmed this finding only for the argon atmosphere. In contrast, in the helium atmosphere, the detection of none of the elements improved. The second assumption is the effect of reducing the ambient pressure, which in combination with an inert gas should allow the detection of fluorine even at low concentrations in the sample. We consider the measured glass disk in chapter 5.7 to be such a sample. This assumption is not confirmed, as the increased intensity of the fluorine spectral line does not manifest itself in any way when the pressure in the vacuum chamber decreases. Finally, in chapter 7 from the results of individual parts of the experiment, the most suitable conditions for the future detection of the measured substances were proposed: fluorine, potassium and calcium fluoride molecules.
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Design of an optomechanical module for laser-induced plasma imaging
Buday, Jakub ; Hrdlička, Aleš (referee) ; Pořízka, Pavel (advisor)
Laser-Induced Breakdown Spectroscopy (LIBS) is a method of analytical chemistry that provides a qualitative and quantitative analysis of a sample. The ablation process of a sample is fast and dynamic and the change of plasma in time and space is a question of a few microseconds. An examination that provides a good time and space resolution is necessary to understand better the physical processes. For this reason, the goal of this thesis is to design a basic optomechanic construction for this type of experiment. Furthermore, it is important to check the functionality of this design and to use it for a basic comparison between the spectroscopic and imaging data. Also, the time development of plasma will be observed under different experimental conditions. The goal of this thesis, in general, is to prove that the morphology of plasma is as it is described in available related literature.
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Interconnection of Restricted Boltzmann machine method with statistical physics and its implementation in the processing of spectroscopic data
Vrábel, Jakub ; Hrdlička, Aleš (referee) ; Pořízka, Pavel (advisor)
Práca sa zaoberá spojeniami medzi štatistickou fyzikou a strojovým učením s dôrazom na základné princípy a ich dôsledky. Ďalej sa venuje obecným vlastnostiam spektroskopických dát a ich zohľadnení pri pokročilom spracovaní dát. Začiatok práce je venovaný odvodeniu partičnej sumy štatistického systému a štúdiu Isingovho modelu pomocou "mean field" prístupu. Následne, popri základnom úvode do strojového učenia, je ukázaná ekvivalencia medzi Isingovým modelom a Hopfieldovou sieťou - modelom strojového učenia. Na konci teoretickej časti je z Hopfieldovej siete odvodený model Restricted Boltzmann Machine (RBM). Vhodnosť použitia RBM na spracovanie spektroskopických dát je diskutovaná a preukázaná na znížení dimenzie týchto dát. Výsledky sú porovnané s bežne používanou Metódou Hlavných Komponent (PCA), spolu so zhodnotením prístupu a možnosťami ďalšieho zlepšovania.
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Mechanism of atomization of selected hydride forming elements in an externally heated quartz tube atomizer and a dielectric barrier discharge atomizer
Juhászová, Lucie ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Atomization conditions for tin hydride in the planar dielectric barrier discharge (DBD) plasma atomizer were optimized with detection by atomic absorption spectrometry (AAS). The effects of apparatus arrangement such as the shape of a waveform function of the high voltage power supply source, DBD atomizer design as well as presence of a dryer tube filled with NaOH pellets to prevent residual aerosol and moisture transport into the DBD were investigated in detail. The optimal experimental setup consisted of a square wave high voltage power supply source coupled to a DBD with vapor-deposited electrodes in the presence of NaOH dryer upstream the DBD atomizer. Argon was found as the best discharge gas under a flow rate of 120 mL min-1 while the DBD optimum high voltage supply rate was 7 kV. A sensitivity of 0.05 s ng-1 Sn and a limit of detection of 1.1 ng mL-1 Sn were reached under optimized conditions. Optimization of the whole experimental setup resulted in 7-fold improvement of sensitivity compared to the original arrangement consisting of a sinusoidal source coupled to a DBD atomizer with glued electrodes in absence of the dryer. Keywords atomic absorption spectrometry, hydride generation, hydride atomization, quart tube atomizer, dielectric barrier discharge (DBD)
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Miniature plasma DBD atomizer for AAS and AFS
Straka, Marek ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Five designs of dielectric barrier discharge (DBD) atomizers have been constructed and optimized employing arsane as a model analyte. The individual DBD designs differed from each other in the style of electrode attachment, electrode shape and area. An externally heated quartz tube atomizer and another DBD atomizer design that have been studied before were used as reference. All the atomizer designs studied including the reference atomizers were found compatible with detection by atomic absorption spectrometry (AAS) giving comparable sensitivity of 0.44 s ng-1 As and detection limit around 0.2 ng ml-1 As under optimum atomization conditions. However, significant differences in optimum operation conditions were found among the DBD designs in terms of the applied voltage depending strongly on the style of electrode attachment. The design with metal strip electrodes glued to a quartz body requires more than 14 kV to be operated. The design with sputtered electrodes of the same shape can reach the same sensitivity with 8.5 kV. Selected DBD designs have been proven to be compatible also with other spectrometric detectors such as atomic fluorescence spectrometry (AFS) reaching detection limit 0.05 ng ml-1 As or atomic emission spectrometry (AES) with detection limit of 30 ng ml-1 As showing the...
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Approaches to signal correction and standardization in laser spectroscopy
Schiffer, Štěpán ; Hrdlička, Aleš (referee) ; Pořízka, Pavel (advisor)
The subject of this diploma thesis is the study of a sample position influence on results of an experiment in laser spectroscopy. The aim is to design an appropriate way for standardization of signal obtained at different conditions with the respect to its applicability for stand-off analysis. In the theoretical part of the diploma thesis there are the basics of LIBS method described together with the issues of stand-off experiment and both, basic and advanced approches for the processing and correction of obtained spectra. Also the experiment is designed here, which is used for the analysis of the sample inclination and distance influence on the detected signal. The choice of appropriate ways for the signal correction follows and their applicability and efficiency is then experimentally tested.
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