National Repository of Grey Literature 20 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Analysis of the porosity of a plaster cast, based on tomography data. Pilot measurement for the feasibility verification of the method for analyses of cast sculptures
Kumpová, Ivana ; Vopálenský, Michal
The aim of the tomographical research was the verification of the feasibility of the X-ray tomography for the qualitative description of the internal structure of the cast sculptures (damage, former restoration evidence etc.) and also for the characterization of the way and direction of the plaster pouring. There is a hypothesis that in the cast piece, the non-uniform distribution of pores as for the size (volume) along the vertical direction should be observable. The deeper in the piece, the higher amount of smaller pores and lower amount of bigger pores is expected. As well, lower porosity, i.e., ratio of the volume of the pores and the entire investigated volume, is expected deeper in the sample. The distribution of the pores could indicate, how the sculpture was made, in particular, where were the pouring holes and how many, what was the material flux like and how did it mixture. The method was verified on a specimen and the indicated hypotheses were only partly confirmed.
Region of interest tomography
Vopálenský, Michal ; Kumpová, Ivana
During standard tomographic process, the acquisition of tomographic data (projections) is performed with geometric adjustment of the tomographic assembly ensuring that the projection of the entire width of the examined object fits onto the detector during the full object rotation. Because of the limited width of the detector, this approach has a limited maximum achievable resolution for the given specimen diameter. It is possible to make higher magnification, but then the projections do not fit onto the detector, which causes certain problems during the reconstruction, but allows achieving of higher resolution in the always-visible region of the object (the region of interest). The research was focused on evaluation of ROI tomography approach on the TORATOM tomograph.
Tomography of a bronze axe of the Únětice culture, found in Kukleny, Hradec Králové
Kumpová, Ivana ; Vopálenský, Michal
It has been shown in the past that the computed X-ray tomography can bear significant new findings on the distribution of damaging and other structural details of the bronze findings. However, relatively high beam energies are necessary and it is not a priori ensured that the object under test would be penetrated with the radiation sufficiently. A big problem is also the photon scattering, which can make fine details indistinguishable. Therefore, a chosen Únětice culture axe has been submitted to a tomographical investigation in the laboratory of X-ray tomography of the Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences, v.v.i. The result should confirm the suitability of the method for investigations of other similar bronze findings.
Design of a suitable length standard for nanp-CT measuring device
Kožiol, Martin ; Jankových, Róbert (referee) ; Šrámek, Jan (advisor)
The diploma thesis deals with the design of three length standards, which will serve to ensure metrological traceability between Rigaku nano3DX, SIOS NMM-1, Zeiss UPMC Carat 850 and other devices located at ÚVSSR BUT and CEITEC Brno. The first part of the thesis focuses on the theoretical acquaintance with concepts closely related to the issue of ensuring metrological traceability. In addition, this section deals with computed tomography and the description of individual devices. The second part of the thesis is devoted to design, production process and testing of individual standards. The last part describes the ensuring the calibration of the smallest standard, the so-called Nano standard and the calculation of the uncertainty of measuring its calibrated length. At the end of the thesis, the outputs of these activities are evaluated.
Reduction Of Metal Artefacts In Ct Data With Submicron Resolution Using Dual-Target Ct
Víteček, Jakub ; Šalplachta, Jiří
The article deals with the possibility of the metal artefact reduction in computed tomography (CT) data with submicron resolution using dual-target CT. The sample is scanned twice at different acquisition parameters, at two different energy spectra. Dual-energy data are then used for easier localisation and segmentation of metal areas and the final combination of low and high-density materials. The final images are compared with the projection-based metal artefact reduction (MAR) algorithm and the commercial program VGStudio MAX 3.1. The results show good functionality of the proposed method and potential for further development.
X-ray nano computed tomography of structured polymeric biomaterials
Kalasová, Dominika ; Oberta,, Peter (referee) ; Kataja, Markku (referee) ; Kaiser, Jozef (advisor)
Tato práce se zaměřuje na pokročilou zobrazovací technologii, rentgenovou počítačovou tomografii (CT). Tato nedestruktivní technika je využívána pro výzkum různých biomateiálů ve tkáňovém inženýrství a materiálové vědě obecně (skafoldy, polymery, keramické materiály, kompozity aj.). Vizualizace a kvantifikace ve 3D jsou výhodné v rámci multidisciplinárního přístupu, který je často v těchto odvětvích uplatňován. Záměr této práce lze rozdělit do dvou oblastí. Prvním tématem je optimalizace měřicí procedury různých měkkých materiálů pomocí CT s laboratorními rentgenovými zdroji. To zahrnuje převážně zobrazování ve fázovém kontrastu, konkrétně metodu volného šíření záření (VŠZ). Tato práce teoreticky popisuje VŠZ a demonstruje tento jev na řadě experimentů. Následné nezbytné zpracování dat získaných VŠZ je implementováno a vyhodnoceno na základě míry zlepšení obrazových dat. Druhé téma ukazuje konkrétní aplikace CT v materiálovém inženýrství. Několik studií s různými CT zařízeními ukazuje příklady možných aplikací a obrazového zpracování. Příklady korelace CT dat s jinými doplňkovými technikami ukazují, jak může být CT aplikována v multioborovém přístupu ke komplexnímu řešení vědeckých problémů.
Possibilities of using 4D computed tomography in fracture tests
Kumpová, Ivana ; Fíla, Tomáš ; Koudelka, Petr ; Rozsypalová, I. ; Keršner, Z. ; Kytýř, Daniel ; Vopálenský, Michal ; Vavřík, Daniel ; Vyhlídal, M. ; Drdácký, Miloš
The paper presents the study of the internal structure and fracture properties of selected quasi-brittle building materials subjected to temperature changes and the possibility of applying the method combining bending fracture tests and time-dependent computed tomography (4D CT). The tested specimens were subjected to hightemperature effects and subsequently tested by a four-point bending during 4D CT. Thus, 3D image information was obtained in different phases of loading and material damage. Comparative compression strength measurements were also performed. These results are in good agreement
Processing of tomographic data by principal component analysis method for archaeological applications
Prokop, David ; Žídek, Jan (referee) ; Pořízka, Pavel (advisor)
Rentgenová počítačová tomografie je metoda sloužící ke 3D zobrazování vnitřní struktury objektů. Mikrostruktura objektů ukrývá důležité informace, které mohou být použity k jejich charakterizaci. Tato práce podává spojení mezi datasety získanými pomocí rentgenové počítačové mikrotomografie a oblastí statistického zpracování dat. Výstupem metody, pak bude klasifikace vzorků na základě informací o jejich mikrostruktuře. Z výsledků klasifikace vzorků, pak můžeme vyvodit různé hypotézy týkající se původu vzorků. Tato práce by mimo jiné mohla sloužit jako takový nový vhled do problematiky kombinace dat různého původu, pomocí metod statistické analýzy.
Reduction of metal artifacts in CT data with submicron resolution
Víteček, Jiří ; Mézl, Martin (referee) ; Jakubíček, Roman (advisor)
This diploma thesis deals with reduction of metal artifacts in CT data with submicron resolution. The first part of this thesis briefly describes x-ray computed tomography followed by the description of artifacts of tomographic images and existing approaches of the reduction of metal artifacts. In the second part proposed methods of reduction of metal artifacts and their implementation in Matlab programming environment are described. Finally functionality of algorithms is tested on a newly created database and the results are compared, evaluated and discussed.
X-ray computed tomography analysis of four test specimens of concrete before and after the frost-resistance test
Souček, Kamil ; Georgiovská, Lucie ; Zajícová, Vendula
The non-destructive 3D X-ray computed tomography method was used to visualize the structure and baseline analysis of changes in the internal construction of two samples of concrete, four test bodies subjected to the frost resistance test. The analyzed samples were scanned on the Nikon Metrology XT H 450 2D / 3T CT Scanner. CT imaging was performed using CT Pro 3D software. The visualization, the preparation of tomographic sections, the analysis of the pore space and the measurement of the dimensions of the test of the bodies were elaborated in VGStudio MAX 2.2 software.

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