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Design of optoelectronic sensor for biological tissues
Balík, Zdeněk ; Bartlová, Milada (referee) ; Tománek, Pavel (advisor)
Biological tissues are optically inhomogeneous and absorbent materials. They are comprised of various structures such as cells, cell organelles, and various fiber structures. Due to these structures leads to different interactions with the light and phenomena such as absorption, scattering and polarization of light. Different ultrasonic, electromagnetic, electrical and optical methods are used for meat ageing detection. Muscles are turbid anisotropic media, they exhibit changes in electrical and optical properties according to the direction of the electrical and optical fields in the sample. The diploma work assesses the feasibility of impedance measurements for meat ageing detection and their comparison with optical measurement of scattered polarized light. Two different sample were used: pork chop slices and chicken breasts were used for their relative homogeneity. The electrical method is a promising method due to the possibility of getting much information and realizing cheap and fast enough measurement systems. The proposed optical method allows measure the rotation of polarization plane with meat ageing in the range of 95 degrees within considered period. Through the first promising results obtained in this thesis, a further work has to be provided to determine closer relationship between optical scattering characteristics, electrical anisotropy in ageing-related tissue structural properties.
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Electrical characteristics of gliding discharge for VOC decomposition
Jeřábek, Martin ; Sysel, Petr (referee) ; Bartlová, Milada (advisor)
The subject of this bachelor's thesis was to get familiar with the characteristics of plasma, its divisinon and diagnostics. In physics and chemismy plasma is considered to be, an ionized gas composed of ions, electrons (and possibly neutral atoms and molecules), which is produced by detachement of electrons from the atomic shell, or by dissociation and ionization of molecules. The plasma is often referred as the fourth state of matter. Attention was given to the description of various types of electric discharge, its characteristics and occurrence. One of the most idey known electrical discharges occurring in nature is lightning, a spark discharge, which occurs in the storm. Lightning is an electric discharge between centres of positive and negative charge of one or more clouds, between cloud and earth, or rarely between the cloud and the stratosphere. The greatest attention is paid mainly to gliding electric arc discharge, called Glide-Arc; it is a representative of on-thermal plasma formed by weakly ionized gas. It has many industrial applications, especially for its high energy efficiency, specific productivity and high selectivity of chemical reactions. Under low and atmospheric pressure, Glide-Arc represents a simple and non-expensive way of non-thermal plasma generation. The discharge is excited between two electrodes of different materials in the pressure range from very low pressures up to the pressures of the order of units of MPa. The gliding arc system consist of horn-gaps electrodes diverging in the direction of the working gas flow. After the application of DC or AC voltage, a breakdown occurs at the smallest distance between the electrodes, and a spark plasma channel drifts (“glides“) in the direction of the flowing gas. The final experimental part deals with the measurement of VA characteristics and oscillation characteristics of the current, and with the determinativ of gliding arc ignitron for selected of nitrogen and methane gases at various flow rates. The values of ignition voltage for variol mixtures of gases have been compared. Furthermore, the properties various combinations of gases at different gas flow rates have been evaluated. Measurements were carried out in the plasma laboratory of the Faculty of Chemistry BUT in the plasma reactor at the atmospheric pressure.
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Effect of a switching arc on design of low voltage switchgear
Šimek, David ; Bartlová, Milada (referee) ; Aubrecht, Vladimír (advisor)
The first part of the master thesis is focused on theoretical analysis of the problems of diagnostics of an electric arc physical properties. In the thesis there is shown identification of spectral lines in experimentally measured electric arc spectra. The thesis deals also with energy balance of the arc. Next part of thesis is aimed to theoretical analysis of effects of electric arc on construction materials of low voltage electric apparatuses. The main part of thesis is devoted to experimental measurement of arc radial temperature changes, measurement of cathode temperature and research of electrical arc effect on selected construction materials of low voltage apparatuses.
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Electrical features of barrier discharge for microorganism sterilization
Bernát, Jan ; Pfeifer, Václav (referee) ; Bartlová, Milada (advisor)
This thesis deals with barrier discharge through gases from the point of view of electrical attributes and processes that, which are going on in a discharge. The research of a discharge itself is preceded by theoretical discourse about plasma and its attributes and basic information about barrier discharge. Second part deals with processing measured data on an experimental device and is followed by making deduction. The main role is relating instantaneous power P[W] and power drain Pel[W] to supply voltage. Nitrogen and argon gases were used and the experimental measuring device was set in different configuration of gas flow velocity, distance between electrodes, used frequency of a supply voltage and its different level. An algorithm decribing proceding with another data measuring is described in this thesis. The scope of the thesis does not allow for thorough examining of each aspect, which was measured or deduced from data analysis. However the the thesis addresses these aspects and suggests further research.
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Theoretical - practical view of the levitation of the lifter
Buday, Matej ; Bartlová, Milada (referee) ; Zdražil, Vladimír (advisor)
Levitation and its effects becomes a huge trend of modern physics. It is very important to be accurate and patient in the research. Representative of the theory, which we are examining, is a lifter and its levitation in electrostatic field. Air ionization is produced by high voltage connected to the lifter’s electrodes and a beam of plasma will surround a thin wire electrode. The levitation effect will appear, if there is right magnitude of electric field intensity and right method of lifter construction.
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Calculation of Standard Thermodynamic Functions of Simple Compounds under Thermal Plasma Conditions
Živný, Oldřich ; Bartlová, Milada (referee) ; Křenek, Petr (referee) ; Krčma, František (advisor)
The substance of present work is to provide standard thermodynamic functions (STF) of small size molecules for the calculation of the composition and thermodynamic properties of low-temperature plasma, and also method for such a calculation applying obtained STF under non-ideal plasma conditions. With a view to further application in modelling the phenomena in thermal plasma the range of pressures is limited to the region from 0.01 bar to 100 bar, and that of temperature to 298.15–50 kK. To obtain STF the method of partition function resulting from statistical mechanics was proposed. State of art in the given scientific area and theoretical basis of the statistical mechanics required for establishing of the proposed method together with discussion of partition function divergence problem have been reviewed. For the calculation of STF of diatomic molecules the method of direct summation has been employed, whereas, as for the larger size molecules, the rigid rotor and harmonic oscillator model have been generally adopted. The spectral data required for the calculations have been taken from literature, or, in selected cases, these have been computed by quantum chemistry ab initio techniques. The resulting STF have been included into already existing database system of thermodynamic properties and those can serve as input data for subsequent thermodynamic calculations. A general method has been worked out for the purpose of the computation of thermodynamic properties and composition of non-ideal homogenous plasma system in thermodynamic equilibrium. The method is based on minimizing total Gibbs energy to compute at constant pressure or Helmholtz energy to compute at constant volume. The computation algorithm was implemented into computer program and subsequently applied to the computation of the composition and thermodynamic properties of SF6 dissociation and ionization products using obtained STF.
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Influence of humidity on total sterilisation effect of dielectric barrier discharge
Kramárová, Petra ; Bartlová, Milada (referee) ; Kozáková, Zdenka (advisor)
The main subject of this diploma thesis is the study of the effect of humidity on the total sterilization effect of the dielectric barrier discharge. Sterilization is a process which can eliminate all forms of life. The plasma sterilization is one of the methods that are suitable for sterilization of temperature and chemical sensitive materials. This sterilization method was proved to be effective on the wide spectrum of procaryotic and eucaryotic microorganisms. Basically, the main inactivation factors for cells exposed to plasma are heat, UV radiation and various reactive species. Dielectric barrier discharge (DBD) operating at atmospheric pressure was used for the sterilization of the samples. The discharge was generated in dry air and in humid air. The plasma power densities were 2 160 mW.cm-3, 2 279 mW.cm-3 and 2 760 mW.cm-3 (dry air) or 2 326 mW.cm-3 and 2 850 mW.cm-3 (humid air). Humidity of air was achieved using a wash bottle filled with water through which air flowed into the DBD reactor. Fungi spores of Aspergillus niger were used as model microorganisms. Whatman paper No. 1 was used as the carrying medium. When comparing sterilization efficiency of humid and dry air operating at the same conditions, the higher sterilization effect was observed in humid air. The sterilization effect of the DBD generated in air was compared with results obtained during plasma generation in argon and nitrogen. At the same conditions, the highest sterilization effect was observed in argon, followed by humid air, nitrogen and dry air. It was found out that in our experimental setup the active species are probably the main inactivation mechanism. The influence of temperature on the inactivation of microorganisms was completely negligible. The discharge parameters were studied by means of the optical emission spectroscopy (OES). Plasma treated samples were analyzed employing scanning electron microscopy (SEM). Damage of the microorganisms due to the effect of plasma as well as plasma effect on the structure of the carrying medium was evaluated.
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Radiation Transfer of Energy in Arc Plasma
Bogatyreva, Naděžda ; Kapička, Vratislav (referee) ; Jeništa,, Jiří (referee) ; Bartlová, Milada (advisor)
Hlavním cílem práce je studium radiačního přenosu energie v termálním plazmatu pomocí aproximační metody sférických harmonických funkcí (PN-aproximace). Práce má teoretický charakter. Pozornost je věnována především P1-aproximaci. Spektrální závislost absorpčních koeficientů byla zpracována pomocí multigroup aproximace. Byl vytvořen výpočetní program pro výpočet radiačních charakteristik v izotermickém válcovém plazmatu a ve válcovém plazmatu s daným teplotním profilem, a vypočteny radiační charakteristiky pro plazma vzduchu a směsí SF6 a PTFE. Získané výsledky umožňují zahrnout radiační ztráty energie do celkové energetické bilance plazmatu elektrického oblouku. Jsou využívány v matematických modelech elektrického oblouku, které vytváří naši spolupracovníci z Ústavu fyziky plazmatu AV ČR v Praze a také ze zahraničních pracovišť (ABB Corporate Research ve Švýcarsku a Siemens AG Corporate Technology v Německu).
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