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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Laserový vibrometr s 2D rozmítáním / Laser vibrometer with 2D scanning system

Rajm, Martin January 2012 (has links)
This thesis deals in the theoretical part with the non-contact vibration measurement by single point Laser Doppler vibrometer and it concretes constructions used in practice. It deals also with the possibilities of the laser beam scanning to measure the vibrations in the plane and there are also listed suitable-commercial systems for this solution. Mentioned sweep is immediately necessary for 2D scanning vibrometer construction. In the practical part, the single-point laser vibrometer OFV-5000 was expanded by scanning galvo system, supplemented by a measuring cards for signal acquisition from the vibrometer and suitable control hardware was chosen for mentioned laser. For the resulting hardware assembly was designed and implemented in LabVIEW measurement software, to control the 2D scanning system, to set the position of the laser beam and to process and to visualize of measured vibration signals in the plane. The functionality of the developed measuring system was checked by performed measurement and visualization of the velocity vibration of restraint girder, excited by shaker.
22

Nové materiály pro Li-iontové baterie pracující na principu konverze / New materials for Li-ion batteries with conversion mechanism

Petr, Jakub January 2014 (has links)
This thesis is interested in new materials for lithium – ion batteries. Two different samples were investigated, one intercalation and one conversion cathode material. The theoretical part is focused to the structure of cells, their advantages and disadvantages compared to other secondary batteries. Also other materials used in batteries are described. The practical part describes the preparation of cathode materials for subsequent testing by scanning elektron microscopy and thermogravimetric analysis. In conclusions two different materials were evaluated and compared with each other.
23

AKTUALIZACE DTMM S VYUŽITÍM MOBILNÍHO SKENOVACÍHO SYSTÉMU / UPDATE OF DTMM USING MOBILE SCANNING SYSTEM

Cimpl, Tomáš January 2013 (has links)
This diploma thesis deals with the updating of digital technical city map. Specifically with map updating using data from mobile scanning system and a comparison with map updating performed without the use of a mobile mapping system. Aim of the thesis was to update the digital technical map of Pardubice in the range of map sheet Pardubice 8-1/21.
24

Reologické chování roztoků polymeru vhodných pro elektrostatické zvlákňování / The Rheological Behavior of Polymer Solutions Suitable for Electrospinning

Divínová, Nikol January 2017 (has links)
This diploma thesis deals with preparation and characterization of aqueous solutions of polyvinyl alcohol suitable for electrospinning. In the theoretical part method of electrospinning is described, including parameters which influence this process. Literary research also includes a chapter about rheology, which deals with the rheological properties of polymers, specifically PVA. The experimental part describes the preparation and rheological study of of aqueous solutions of polyvinyl alcohol, which were then spun. The morphology of prepared nanofibers was studied by using scanning electron microscopy (SEM). The effect of molecular weight, the solvent, concentration of solution, rheological properties, electrical conductivity and surface tension on the spinability, diameter and morphology of nanofibers is discussed.
25

Metastabilní slitina Ti-15Mo připravená práškovou metalurgií / Metastable alloy Ti-15Mo prepared by powder metallurgy

Veverková, Anna January 2019 (has links)
This diploma thesis focused on manufacturing and characterization of Ti-15Mo metastable beta-Ti alloy prepared by cryogenic milling and spark plasma sintering. Initial powder was prepared by gas atomization and consequently deformed by cryogenic milling (milled powder). Both initial and milled powders were compacted by spark plasma sintering (SPS) at temperatures from 750 řC to 850 řC. Dependence of microstructure and mechanical properties on the parameters of preparation was studied. During cryo-milling, powder particles significantly changed shape from ball-shaped to disc-shaped. Particles were not refined by milling, but severely plastically deformed. SEM observations showed that all prepared samples contain duplex alpha + beta structure. Volume fraction of alpha phase is significantly higher in the sintered milled powder due to increased beta- transus temperature caused by contamination by oxygen and also due to easier alpha phase precipitation caused by refined microstructure. Maximum microhardness of 350 HV was achieved for both types of sintered powders. High microhardness of sintered initial powder can be attributed to formation of omega phase during cooling, while sintered milled powder is strengthened by refined microstructure and small alpha phase precipitates. Cryogenic milling prior to...
26

Vysoce uspořádané tenké vrstvy oxidu kobaltu pro modelovou katalýzu / Highly ordered cobalt oxide thin films for model catalysis

Ronovský, Michal January 2020 (has links)
Hydrogen processing is becoming increasingly important not only in the production of electricity but also during its accumulation. One of the energy storage options are liquid organic hydrogen carriers (LOHC). The main drawback of LOHC is the need for a large amount of thermal energy to release molecular hydrogen. We can bypass this issue using heterogeneous catalysis by transferring hydrogen from LOHC to acetone and using the produced 2-propanol (IPA) in the fuel cell. This innovative strategy of getting electri- cal energy from LOHC can be potentially energetically neutral. In this work, we studied highly ordered Co3O4(111) model catalysts for IPA oxidation in the as-prepared state and enhanced with platinum (Pt) nanoparticles. Catalysts were prepared by Physical Vapour Deposition (PVD) and further investigated by means of Low Energy Electron Diffrac- tion (LEED), X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Temperature Programmed Desorption (TPD). The nucleation process of Pt on the as-prepared Co3O4(111) surface was studied by depositing low amounts 0.04 and 0.13 monolayer (ML) of Pt, that create clusters as small as 2 or 3 atoms with no need for a special nucleation site. We have identified the formation of Pt-induced defects in the atomically flat cobalt oxide...
27

Precipitační procesy v lehkých vytvrditelných slitinách a možnosti začlenění termické analýzy do středoškolské výuky fyziky / Precipitation processes in light hardenable alloys and the possibilities for integrating thermal analysis into physics education on high school

Kodetová, Veronika January 2020 (has links)
The doctoral thesis is divided into two parts - Thermal analysis in physics education on high school and Material research of Al-Zn-Mg(-Cu-Sc-Zr) alloys. Within the first part, the areas of crystallization and/or melting of selected foods were determined using differential scanning calorimetry. A practical lesson for high school physics has been created and tested. The study text focused mainly on differential scanning calorimetry and its use was made. In the second part of the doctoral thesis, there was analysed thermal evolution of the phase transformation in the Al- Zn-Mg(-Cu) alloys with Sc and Zr addition. The effect of (cold and hot) deformation on the decomposition sequences was studied. The hardening effect after annealing above 300 řC in the Sc and Zr alloys is caused by the precipitation of the secondary Al3Sc,Zr) particles. These particles were observed by transmission electron microscopy after annealing up to 360 řC in all studied AlZnMg(Cu)ScZr alloys. In the AlZnMgCu alloy the partial recrystallization was observed after annealing at 350 řC/10 hours and after annealing at 450 řC/10 hours the grain size was 50-200 m (depending on the treatment of the alloy). The addition of Sc, Zr in the AlZnMgCuScZr stabilizes grains and there is no recrystallization in the AlZnMgCuScZr alloy at temperature...
28

Studium vlivu vlhkosti na celkový sterilizační účinek dielektrického bariérového výboje / Influence of humidity on total sterilisation effect of dielectric barrier discharge

Kramárová, Petra January 2012 (has links)
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.
29

Studium defektů v tenkých kovových vrstvách / Studium defektů v tenkých kovových vrstvách

Hruška, Petr January 2014 (has links)
In the present work Mg films prepared by RF magnetron sputtering were studied. Variable energy positron annihilation spectroscopy (VEPAS) was employed for investigation of defects in the Mg films. VEPAS characterization was combined with scanning electron microscopy and X-ray diffraction in order to determine grain size, phase composition and texture. The effect of different deposition rate and deposition temperature, annealing, various substrates and film thickness on the structure and amount of defects present in the Mg films was examined. Defect studies by VEPAS showed that positrons in studied Mg films are trapped at misfit dislocations and at vacancy-like defects in grain boundaries and their density can be reduced by the deposition at elevated temperature. 1
30

Sledování tvorby plovoucího biofilmu Mycobacterium smegmatis - morfologická a proteomová analýza / Monitoring of Mycobacterium smegmatis floating biofilm development - morphological and proteome analysis

Sochorová, Zuzana January 2012 (has links)
Microorganisms grow in planktonic form, but more often they adhere to a number of surfaces and create three-dimensional structures called biofilms. Floating biofilms, which are formed at the water-air interface, are one of the life strategies, which the bacteria can take. Non-pathogenic Mycobacterium smegmatis was used as a laboratory model for the study of this kind of biofilm. The understanding of mechanisms of their formation of this species may be applicable to the pathogenic species of the genus Mycobacterium, study of which in the laboratory brings a number of disadvantages. This diploma thesis focuses on the morphological and proteome analysis of the M. smegmatis floating biofilm. Using a stereo microscope and scanning electron microscopy was observed that bacteria clump and create the "nucleation centres" at the beginning of the biofilm development. This centers grow to the surroundings and connect afterwards. In the later stages of the development the centers fuse in compact layer, which then grows into the compact and multilayer biofilm. The key method in this study was two-dimensional electrophoresis of proteins. The proteome analysis of floating biofilm was performed with this method. The preparation of protein samples and the method for protein concentration measurement was optimized....

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