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Creation of spectral lines database of selected standards for Laser-induced Breakdown Spectroscopy (LIBS) and double pulse Laser-induced Breakdown Spectroscopy (DP LIBS)
Mazura, Martin ; Sládková, Lucia (referee) ; Kaiser, Jozef (advisor)
Laser-Induced Breakdown Spectroscopy (LIBS) has a great potential across a different fields of use. Wide use of this method is still complicated because of some problems. The most important problem is difficult analysis of obtained measurement results. Nowadays mostly used analysis is based on comparison of measured data with databases created in different way. This bachelor’s thesis deals with creation of spectral lines database for LIBS and it also shows the methodology for spectral lines database assembling. Theoretical basis of the method and experimental setup used for measurements is described in the first part of this thesis. Further, there are described measurements of standards and creation of database. The result of this work presents a database of spectral lines containing 14 elements and more than 500 spectral lines. In order to illustrate database utilization it was established composition of an unknown sample.
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Investigation of Madonna in the travel altar of Robert of Anjou from the collection of moravian gallery in Brno
Fogaš, I. ; Wörgötter, Z. ; Hradilová, J. ; Hradil, David ; Zikmund, T. ; Kaiser, J.
An exceptional Gothic work of art, a travel altar of Robert of Anjou, is one of those donated by John II of Liechtenstein to the Franz Museum in Brno in 1896. Light has been newly shed on the circumstances of Prince's acquisition of the altar; it refuted the thoughts about the altar's Central European provenance, because as it is being documented, the purchase took place directly in Florence in 1890. It has been recorded already back then that the Tabernacle is complemented by a (damaged) statuette of Black Madonna made of Carrara marble. The description of its damage, secondary additions and polychromy construction was the main aim of the artwork's survey by non-invasive methods (mobile XRF, computed tomography); on the basis of their results, a careful micro-sampling has been performed followed by material analysis. Most importantly, it was found out that the material of the statue is not Carrara marble, but an alabaster, which is not in disagreement with the assumed provenance (northern Italy), but due to its weight and fragility, the statuette could only hardly be an original part of the altar. Concurrently, the analysis of the oldest layers of polychromy proved that the Madonna has not been originally black and that this adjustment has been executed secondarily and intentionally.
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Investigation of Madonna in the travel altar of Robert of Anjou from the collection of moravian gallery in Brno
Fogaš, I. ; Wörgötter, Z. ; Hradilová, J. ; Hradil, David ; Zikmund, T. ; Kaiser, J.
An exceptional Gothic work of art, a travel altar of Robert of Anjou, is one of those donated by John II of Liechtenstein to the Franz Museum in Brno in 1896. Light has been newly shed on the circumstances of Prince's acquisition of the altar; it refuted the thoughts about the altar's Central European provenance, because as it is being documented, the purchase took place directly in Florence in 1890. It has been recorded already back then that the Tabernacle is complemented by a (damaged) statuette of Black Madonna made of Carrara marble. The description of its damage, secondary additions and polychromy construction was the main aim of the artwork's survey by non-invasive methods (mobile XRF, computed tomography); on the basis of their results, a careful micro-sampling has been performed followed by material analysis. Most importantly, it was found out that the material of the statue is not Carrara marble, but an alabaster, which is not in disagreement with the assumed provenance (northern Italy), but due to its weight and fragility, the statuette could only hardly be an original part of the altar. Concurrently, the analysis of the oldest layers of polychromy proved that the Madonna has not been originally black and that this adjustment has been executed secondarily and intentionally.
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Changes in dislocation substructure of S235JR steel during fatigue loading
Jandová, D. ; Gajdoš, Lubomír ; Šperl, Martin ; Kaiser, J.
Changes in dislocation substructure were studied in normalized and annealed S235JR steel in relation to the number of symmetrical reversed stress cycles with the amplitude σa = 242 MPa and corresponding mean life Nf = 17,950 cycles. The microstructure of the steel consisted of ferrite with a small amount of pearlite. The substructure was observed in as received condition and after application of various relative numbers of cycles n/Nf, these being 0.25, 0.50 and 0.75. An irregular dislocation net occurred in the virgin specimen, however, during cyclic loading the dislocations started to accumulate gradually in slip bands and to form a cell substructure in grains of favourable crystallographic orientations. Total dislocation density, dislocation density in slip bands and inter-band distance were measured using transmission electron microscopy (TEM). The total dislocation density was found to slightly decrease and the density in slip bands to increase with increasing number of cycles. The results concerning the dislocation density were compared with changes in the microplastic limit (MPL) which were determined by the measurement of the inductance of the “specimen - coil” system. They consisted in a rapid initial decrease at the first stage of the fatigue process and in a gradual increase during the major part of the life. These changes can be interpreted on the basis of changes in dislocation density as was verified independently by X-ray diffraction and nanoindentation tests. On the basis of the measurement of dislocation density by TEM it appears that changes in MPL can be connected with the dislocation density in slip bands rather than with the total dislocation density.
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Micro-plastic limit of low-carbon steel CSN 41 1375 as determined by the measurement of electrical impedance
Gajdoš, Lubomír ; Šperl, Martin ; Kaiser, J. ; Mentl, V.
It is generally accepted that not all cyclic stresses below the fatigue limit are non-damaging. Particularly in spectrum loading, the inclusion of some cyclic stresses below the fatigue limi can reduce the fatigue life of a component. It is believed that the boundary between damaging and non-damaging stresses is the so-called micro-plastic limit (MPL) defined as a macro-stress at which dislocation pile-up stresses begin to obstruct the magnetic domains in rotation to the direction of the tensile stress. This paper shows that MPL can be determined from changes in magnetic permeability during tensile loading. In our work, changes in magnetic permeability were measured indirectly - by measuring changes in electrical impedance (a.c. resistence and induktance). Measurements were performed on normalized low-C steel CSN 411375, and the microplastic limit was determined by evaluating
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