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Local structure of hexagonal ferrites studied by NMR
Kouřil, Karel ; Štěpánková, Helena (advisor) ; Pištora, Jaromír (referee) ; Schneeweiss, Oldřich (referee)
Title: Local structure of hexagonal ferrites studied by NMR Author: Karel Kouřil Department/Institute: Department of Low Temperature Physics Supervisor of the doctoral thesis: prof. RNDr. Helena Štěpánková, CSc. Abstract: Hexagonal ferrites of M, W, X and Y structure types were studied by means of NMR, electronic structure calculations and magnetoelectric experi- ments. Presented results deal with cation distribution, localization of ferrous ions, interpretation of NMR spectra of studied materials and effects of size reduction. In oriented layers M type strontium ferrite and submicron particles of M type barium ferrite pronounced effects of reduced size were observed on 57 Fe NMR spectra. Performance of magnetoelectric barium-strontium Y type hexaferrites with divalent zinc cations improved upon thermal treatment of samples while distribution of zinc was not significantly altered. In Sc sub- stituted BaM, Sc content was found to be uniform throughout TSSG grown crystal. In LaSrM systems electron localization in 2a sublattice was observed, co-substitution with La+Zn, La+Co and La+Cu was found to lead to partial charge compensation. In strontium ferrites of type W and X localization of ferrous ions in octahedral sites in SS block pair was observed. Keywords: NMR, hexagonal ferrites, structure,...
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Wettability of PCB Surface Finishes and Comparison of Methods
Vídeňský, Ondřej ; Přikryl, Tomáš (referee) ; Starý, Jiří (advisor)
This bachelor´s thesis deals with testing methods for surface finishe´s wettability PCB. For this tests has been designed and created testing board which contains testing coupons for testing methods. Boards have been created and covered by surface finishes by Gatema Boskovice. In this thesis electroless nickel with immersion gold (ENIG) and immersion tin have been tested. For simulation of reflow soldering have been used test methods solder indicator, solder spread test and dewetting test. Wetting balance test method has been used as simulation of wave soldering.
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Dynamics of structural defects in CdTe-based semiconductors
Bugár, Marek ; Belas, Eduard (advisor) ; Holý, Václav (referee) ; Fochuk, Petro (referee)
Title: Dynamics of structural defects in CdTe-based semiconductors Author: RNDr. Marek Bugár Institute: Institute of Physics, Charles University in Prague Supervisor of the doctoral thesis: Doc. Ing. Eduard Belas CSc.; Institute of Physics, Charles University in Prague Abstract: The work was aimed at investigation of the effect of annealing on structural, electrical and optical properties of CdZnTe epitaxial substrates and CdTe-based and CdZnTe-based X-ray and gamma-ray detectors. The first part of the work is focused on investigation of structural properties of one type of second phase defects - inclusions - present in the material, which degrade the material quality. Consequent annealing experiments were aimed at reduction of these defects. In case of CdZnTe substrates, an annealing treatment leading to increase of the infrared transmittance was investigated. On the other hand, annealing experiments on the detectors of high-energetic radiation were focused on preservation of the high-resistive state. Moreover, the work contains detailed measurements of transport properties of CdTe taken directly at high temperatures. Key words: CdTe, annealing, inclusions, detectors, defects
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Nuclear magnetic resonance in yttrium-iron garnets with cobalt and germanium substitutions
Schimm, Petr ; Štěpánková, Helena (advisor) ; Rotter, Miloš (referee)
Title: Nuclear Magnetic Resonance of Yttrium Iron Garnets with Substitutions of Cobalt and Germanium Author: Petr Schimm Department: Department of Low Temperature Physics Supervisor: prof. RNDr. Helena Štěpánková, CSc., Department of Low Temperature Physics Abstract: The work is devoted to investigation of thin films of nominally pure yttrium iron garnet and garnets containing cationic substitutions of Co, Ca and Ge. The examined samples were prepared by epitaxial growth from barium flux BaO/Ba2O3/BaF2. The aim was to find whether and how the substitutions, especially cobalt, influence the spectra of 57 Fe nuclear magnetic resonance (NMR). The 57 Fe NMR spectra (in zero external magnetic field and at a temperature of 4.2K) were measured and a good resolution and high signal-to-noise ratio were reached. The weak satellite lines induced by defects, impurities and aimed substitutions were detected. The primary analysis of the spectra and their comparison were performed. Keywords: NMR, yttrium iron garnet, defects, substitution of Co, Ge, Ca
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The most common diseases of the locomotive system in horses
Bartlová, Aneta ; Navrátil, Jan (advisor) ; Starostová, Lucie (referee)
The most common diseases of the locomotive system in horses
Summary
The domestic horse (Equus caballus), was during the long evolution forced to adapt to changing environments. Especially its limbs have significant change, mainly reduction fingers. For horses are limbs very important, because they provide not only the ability to move, but also physiological processes in the animal body.
The bachelor thesis called The most common diseases of the locomotive
system in horses I was conceived as a comprehensive overview of the most common diseases of the limbs horses. With using a literature, I tried to write just the diseases, which we can meet.
For a better understanding of each disease I consider it important to have at
least basic knowledge of the anatomy of the limbs, hence the first part of this work is focused on the musculoskeletal anatomy of the horse. This chapter is divided into the anatomy of the thoracic and pelvic limbs and the anatomy of the hoof. Anatomy of thoracic and pelvic limbs were also divided according to skeletal and muscular system and also described as important to bones and muscles. Anatomy hoof is also described in detail
The second part is focused on each diseases; podotrochlosis, osteochondrosis,
arthrosis, synovitis, busked shins, ossification, desmitis, laminitis, pododermatitis. Followed by description, formation, diagnosis and therapy.
Of course is important the prevention of these diseases. The proper way of
the breeding on the pastures with plenty of movement a foal. As well as reasonable using horse in the sport, its gradual and reasonable increasing the training load before the top performances.
Keywords: horse, breeding, disease, defects, the locomotor system
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MOISTENING OF COMPONENT MATERIALS AND SPEED OF DEHUMIDIFICATION
Pospíšil, Tomáš ; Tomáš, Bžoněk (referee) ; Starý, Jiří (advisor)
This bachelor thesis deals with process associated with moisture in electrotechnics. The bachelor thesis is focused on the components and basic materials that are sensitive to moisture and defects caused by moisture in the reflow soldering process. The theoretical part describes the principles of measuring humidity and sorts of absorption. Furthermore this work described the basic classification and defects in components, base materials and packaging material sensitive to moisture and selection of standards dealing with this issue. Another theoretical part is focused on the manipulation with components and materials sensitive to moisture. The practical part deals with the methodology and practical measurement of moisture soaking in the components and materials with respect to their level of sensitivity to moisture. The following part is focused on the methodology of drying, practical measurement of drying and comparing two drying cabinets.
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Analysis of Defects on PCB Using Modern Optical Method
Vala, Martin ; Řezníček, Michal (referee) ; Řihák, Pavel (advisor)
This diploma thesis is focused on detecting of defects on BGA (Ball Grid Array) components using of X-ray. Defects are formed during reflow BGA components during assembly, but also later due to mechanical and thermal stress. Therefore, there is an overview of defects and methods of diagnosis of BGA packages eg .: modern X-ray defect detection or micro sections. There is disclosed a device NORDSON DAGE XD7600NT its operation and setup. The device enables advanced methods of scanning called X-plane. For creating 3D models used reconstructive software called CERA, which uses raw data from the method of X-Plane.
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REBALLING OF BGA PACKAGES USING PACE TF2700 EQUIPMENT
Roháček, Peter ; Špinka, Jiří (referee) ; Starý, Jiří (advisor)
The Diploma thesis is focused on reballing of BGA packages with the device PACE TF 2700. It describes the general types of BGA packages, their defects, importance of thermal management to the solder techniques, where it is also talked about the meaning of solders and fluxes for the joint. The work informs about the most common methods of reballing, the proper handling of components and the current situation with BGA stencils on the market. It briefly describes the device operation of PACE TF 2700, that is working on the convection and IR principle of heating components. It deals with the manufacturing of the template, dummy BGA packages, the test plates, creation of the thermo profile, comparing and examining the defects and their causes, which had the most significant impact on the results. The achievements would serve for comparing them with the results of the future laboratory exercises or as a subject for further works.
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Inovation of measurement equipment used for analyzing of photovoltaick cells
Otépka, Jakub ; Bača, Petr (referee) ; Vaněk, Jiří (advisor)
This bachelor thesis deals with the design of a tachometer which is used to measure and display of mechanical aperture speed of a measuring equipment for the defect analysis of solar cells using the photoluminescence method. This work is divided into three parts. The first section describes the principle of solar cells, the principle of luminescence radiation and its types. Next the defects of solar cells are analyzed. The second part discusses the theory of tachometers, the principles and methods of loading pulses. The third part is then analyzed the design and construction of the selected type tachometer.
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Microscopic analysis of silicon solar cells defects
Brukner, Jakub ; Solčanský, Marek (referee) ; Stojan, Radek (advisor)
This thesis deals with detection of defects solar cells using method electroluminescent, electron microscope and subsequent 3D modeling of areas with defects and structure of the solar cell. In the text are describe basic methods for detection of defects appearing in solar cells. Also some basic defects which can be made during manufacture are there describe. For better orientation the basic principle of functionality and manufacturing process is included.
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