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Misalignment aberrations
Dvořák, David
Misalignment aberrations arise from (small) imperfections of lens geometry - either because of the inaccuracy in the manufacturing of individual elements (like electrodes and/or pole-piece defects) or the misalignment of the optical elements in the system (tilted of shifted element). Under suchcircumstances the ideal symmetry is disturbed and additional parasitic fields are produced. In the effect they are producing additional image aberrations.
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Pressure influence on the magnetic and transport properties of the f-electron compounds
Míšek, Martin ; Javorský, Pavel (advisor) ; Kamarád, Jiří (referee)
In this thesis, we describe the work with a new pressure cell, its implementation in Joint Laboratory for Magnetic Studies, together with testing measurements necessary for ensuring good environmental conditions control and trouble-free operation. We have chosen a single crystal of the CePtSn compound to be the first representative measurement. We measured electrical resistivity along crystallographic b-axis in conditions: T = 2-300 K, p = 0-2.5 GPa and magnetic field B = 0-14 T applied along b-axis. We observed only minimal pressure influence on temperatures of magnetic phase transitions, however interesting and rather unusual behavior in magnetic fields was revealed. Previous works reported two field-induced transitions at low temperatures and ambient pressure, with values of the critical fields BcLF ~ 4 T and BcHF ~ 11.5 T, accompanied with large magnetoresistence step of -30% and +10%, respectively. With application of pressure, we observed shift of the critical field of low-field transition BcLF to the higher fields, whereas the value of critical field of high-field transition BcHF was unaffected with applied pressure. At a p ~ 1.5 GPa the two transitions merged and only one step was observed. With pressure further increasing above 1.5 GPa, situation with two transitions, similar to the lower pressure...
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3D scanning technology in the hands of the conservator-restorer
Gláser, Petr
3D scanning technology is undoubtedly a modern progressive techniques that, especially in some areas, are increasingly applied. It is no different in the field of care for our cultural heritage. Relatively simple method brings, thanks to the quick development of means of implementation, still new applications and can deliver a wide range of important information. The devices are user friendly and comparatively affordable. These are just additional reasons for the fact that 3D scanning more applied in the fields of restoration. \nA short paper describes the technique of 3D scanning from the conservator-restorer's perspective and is focused primarily on understanding their capabilities, but does not forget those restrictions, which are always crucial. From time to time there is a tendency to uncritical promotion of certain methods or means. Many similar cases we also known in the field of cultural heritage and it seems that the 3D scanning method is well suited to become the next one.\n
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INFLUENCE OF LASER CUTTING AND PUNCHING ON MAGNETIC PROPERTIES\nOF ELECTRICAL STEEL M470-50A
Bulín, Tomáš ; Švábenská, Eva ; Hapla, Miroslav ; Ondrůšek, Č. ; Schneeweiss, Oldřich
Electrical steel M470-50A belongs to the most often used materials in electrical machines. Due to this fact, it is desirable to know the magnetic parameters after processing raw sheets into the required shape. Basic parameters of mechanical, electrical, and magnetic properties of the sheets are usually obtained from the producer but the magnetic properties are changing in dependence on additional machining processes. The aim of this study is to describe changes in parameters of magnetic behavior after punching, laser and spark cutting of the original sheets. The basic information of structure was obtained by optical and scanning electron microscopy. The magnetic parameters were acquired from the measuring of magnetic hysteresis loops in dependence on saturation fields and frequencies. The results are discussed from the point of view of applied\ncutting technology with the aim to obtain the best magnetic parameters and consequently a higher efficiency of the final product. Results can be used as input parameters in simulation of the electrical machine.
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Solved Problems in Electromagnetism - Magnetic Field
Popová, Markéta ; Koupilová, Zdeňka (advisor) ; Svoboda, Emanuel (referee)
Naxev prace: Rescue iilohy r elekiriny a inagnetismn inagneticke pole Autorka: Market a Popovd Katedra (ustav): Kaledrn diduktiky fvzikv Vedouci bakalafske praee: R\/)r. '/.dcnka tiroklova e-mail vedouciho: ztlenku.hroklova a niJl._c_iini.ci Abslrakl; V ramei bakalafske praee jscni prostudovala shirk}1 uloh / iy/iky nejcaslcji pou/ivane ve vvuce na stfednieh skolach. popfipade v/akladnich kur/ech fyziky na vvsokych skolach. se zamcfenim na kapiloly tykajici se magnetickeho pole. Illavnim cilem bakalarske praee bylo v\lvofeni slrukturovanVch uloh /. kapitoly Mag- netick(j pole, klcrc jsou /vefejueny v ramei |{lektronicke sbi'rky fesenych uloh / Iy/ik\ Kazda uloha obsahuje napo\edu. ro/hor. podrobne reseni. vypoccl a ohvyklc je cloplnc- na na/ornymi obra/k\ Podrohna reseni maji pomoci ctcnafi pfi samosludiu a vest ho k pfx-myslcni nad /adanymi problemy. Ve sbirce jsou /afa/.ens pfxiva/ne obli/nejsi stfedoskolske uloh\. ktere mohou poslou/il jako priprava k maturite nclio k prijiiruiciin /kouskani / f>/iky na vysokou skolu, ale lake nekolik xakladnieh uloh stfediiskolskyeh a ulohy s vysokoskolskou obli'/nosli. Klieova slova: strukturovanc ulohy, magnetieke pole, elektronieka shirka Tille: Solved f'mhlenix in fclecti'owagnetisni Magnetic Field Author: Murkela I'opovt'i Department: DefHirlnieni of Physics...
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ELECTRON BEAM REMELTING OF PLASMA SPRAYED ALUMINA COATINGS
Matějíček, Jiří ; Veverka, J. ; Čížek, J. ; Kouřil, J.
Plasma sprayed alumina coatings find numerous applications in various fields, where they enhance the properties of the base material. Examples include thermal barriers, wear resistance, electrical insulation, and diffusion and corrosion barriers. A typical structure of plasma sprayed coatings, containing a multitude of voids and imperfectly bonded interfaces, gives them unique properties - particularly low thermal conductivity, high strain tolerance, etc. However, for certain applications such as permeation barriers or wear resistance, these voids may be detrimental.\nThis paper reports on the first experiments with remelting of plasma sprayed alumina coatings by electron beam technology, with the purpose of densifying the coatings and thereby eliminating the voids. Throughout the study, several parameters of the e-beam device were varied - beam current, traverse velocity and number of passes. The treated coatings were observed by light and electron microscopy and the thickness, structure and surface morphology of the remelted layer were determined and correlated with the process parameters. Based on the first series of experiments, the e-beam settings leading to dense and smooth remelted layer of sufficient thickness were obtained. In this layer, a change of phase composition and a marked increase in hardness were observed.\n
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