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Time lapse tomography of fracture progress in silicate-based composite subjected to the loading a combination with acoustic emission scanning
Kumpová, Ivana ; Kytýř, Daniel ; Fíla, Tomáš ; Veselý, V. ; Trčka, T. ; Vopálenský, Michal ; Vavřík, Daniel
The initiation and propagation of a fracture in quasi-brittle materials (such as silicatebased composite) is an increasingly discussed topic for which various methods of research have been developed/applied. As the quasi-brittle silicate-based composite compounds are very non-homogenous, the mechanism of the crack initiation and propagation can be very different even for samples with the\nidentical geometry. One possible approach to study the fracture mechanism in quasi-brittle materials is to use several different experimental techniques in a single experiment and perform detail analysis to identify generally valid fracture process phenomena. In this work, a simultaneous monitoring of fracture\nprocess zone formation and propagation by three different methods is presented and discussed. A three point bending test was performed on a notched silicate composite specimen. During the loading process, a highly accurate force displacement dependence was recorded accompanied with X-ray radiography,\nX-ray computed tomogra-phy and acoustic emission scanning.
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Radiotherapy planning
Kumpová, Ivana ; Sekora, Jiří (referee) ; Kolářová, Jana (advisor)
The task of this thesis is to familiarize readers with the basics of the problem of ionizing radiation from its types and resources, through mechanisms of action and its effects on the human organism, to the possibility of calculating various characteristics. Close attention is paid to the use of ionizing radiation in medical approaches. There is in detail described process of radiotherapy planning and a basic properties of planning systems. Part of the thesis is also program RT-Plan processed in Matlab. The program simulates the planning system for external ionizing radiation therapy used in treatment. There is supplemented a detailed help and series of tests for the plan. It is suitable for possible use in teaching.
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The Influence of Environment on the Short-Term Quality of Hearing
KUMPOVÁ, Ivana
Sound is one of the fundamental parameters monitored during the classification of work hygiene. More and more attention has been paid to the evaluation and management of noise outdoors. Frequent exposure to noise may result in hearing impairment. Exposure to a loud sound results in an acute increase of the threshold of audibility, especially for frequencies similar to those of the given sound. However, the hearing goes back to normal after a certain period of time. Repeated exposure to the high intensity sounds shifts the threshold of audibility gradually but permanently upwards. The loss of hearing gradually excludes people from regular life and forces them to compensate their disability. As a preventive measure in the working environment the employers shall provide to their employees hearing protection aids in order to eliminate such cases. The main objective of this thesis was to prove the harmful effect of noise on hearing in the working environment and to propose potential solutions. The project also refers to the efficiency of employment of hearing protection aids in a noisy working environment. This bachelor thesis deals with a survey of thresholds of audibility among workers of an engineering factory, depending on various noise conditions in the working environment. Audiometric curves of persons exposed the sound intensity exceeding 85 dB for a prolonged period of time were taken immediately after the exposure (after the working hours). The measured data were compared with reference audiograms taken after a quiet period (before the working hours). Dependence of changes in the threshold of hearing on various factors was investigated for the individual surveyed persons, while in practical terms the most important one was the dependence on the type of the employed hearing protection aids. The thesis also evaluates how the hearing loss is affected by the noise level at the workplace, method of transport to work and frequency of the sound.
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