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Experimental evaluation of aluminothermic welds
Zeman, L. ; Valach, J. ; Zlámal, P. ; Krčmářová, N. ; Koudelková, Veronika ; Zeman, J.
The article presents a study of the mechanical processes occurring during the aluminother-mic reaction using experimental methods (strain gauges, digital image correlation, thermography,scanning electron microscopy, profilometry). The aluminothermic reaction is a highly efficient weldingmethod due to its exothermic behaviour, however, it places considerable demands not only on thewelding technique, but also on the capabilities of the experimental methods used - these limitationsare also discussed in the article. The aluminothermic reaction is associated with the formation of alocalised heat source with a time evolution dictated by the technological procedure, which manifestsitself in heat propagation to the surrounding weld material. The unequal evolution of the temperaturefield is the fundamental cause of the appearance of the heat affected zone or local deformations orsurface curvature, which was the focus of the experimental methods deployed above and the results ofwhich are shown in the article.
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The effect of the covid-19 pandemic on the spatial organisation of air transport in Africa.
ZEMAN, Jan
The key topic of this bachelor thesis is the analysis of the spatial organization intracontinental of the air transport in Africa in 2019 and 2020 when it was affected by the covid 19 pandemic. In the introductory part, the bachelor thesis is presented, the objectives of the thesis are set and also hypotheses that will be later confirmed or refuted. The introductory part is followed by the theoretical part where the theory of the air transport is introduced, concepts related to this mode of the transport in general and then concepts that are typical for transport in Africa. In the second part of the thesis is a transition from the theoretical to the analytical part. The analytical part has two subchapters, the first deals with the analysis of the domestic air transport in 2019 when it was not yet limited by the covid 19 pandemic. The second subchapter is 2020 when the covid 19 pandemic has already greatly affected air transport. The data for processing the analysis are from the ICAO - International Civil Aviation Organization database. Based on this data, intracontinental air transport was compared between 2019 and 2020 when the covid 19 pandemic was spreading.
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Mezioborová spolupráce v koordinované rehabilitaci pohledem dvou oborů: sociální práce a fyzioterapie
ZEMAN, Jaroslav
The coordinated rehabilitation approach is considered to be an expected approach to the patient who, among other things, fulfills fundamental human rights. Coordinated rehabilitation is a demanding process that places great demands on interdisciplinary cooperation. Social workers and physiotherapists often contact the client / patient earlier as part of a coordinated rehabilitation. In the theoretical part, this work describes the current state, tries to reflect the challenges of today, further clarifies physiotherapy and social work, how these fields are understood in the Czech Republic in the early 21st century. , also the benefits and obstacles of coordinated rehabilitation. Practical part. The research question of the thesis is whether coordinated rehabilitation is used in the practice of social work and physiotherapy. It compares views of social work and physiotherapy. Using the grounded method (GTM), the phenomenon gradually appears in the work, when on the one hand social workers and physiotherapists see the benefits and possibilities of coordinated rehabilitation, on the other hand the description of practical use of KR does not correspond to the theoretical anchoring of KR. Thus, the work further deepens the knowledge and tries to understand this phenomenon more, chooses subjective obstacles, which he describes in more detail according to the research. In the discussion, the works need possible connections between motivation and philosophical conception of a person to cooperate in a coordinated rehabilitation. Answers research questions. It compares how the views of physiotherapy and social work differ and discusses the results with current professional literature. I summarize everything in the end of the work.
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The Relationship Between the Function of the Spinal Cord and the Width of the Spinal Canal Depending on the Change in the Axis of the Cervical Spine
Žídek, Slavomír ; Holečková, Irena (advisor) ; Zeman, Jaroslav (referee) ; Česák, Tomáš (referee)
Introduction: The aim of our study was to assess the effect of dynamic changes in spinal flexion and extension assessed by dynamic magnetic resonance imaging(dMRI) on spinal cord functions assessed by dynamic evoked potentials(dEPs) in group of healthy individuals (group 1) and in group of patients with a small graphical pathology on cervical spine MRI in the neutral position, but with mild objective and progressive subjective difficulties (group 2). Methodology: 10 healthy individuals and 10 patients were included in the study. Examination of dMRI as well as dEPs was performed in neutral position, flexion and extension. The anterior (PD) and posterior spinal cord length (ZD), transverse (PR) and anteroposterior dimension (PZ) and spinal cord area (P) were measured on the cervical spine MRI. The median and tibial nerves SEPs (somatosensory evoked potentials) and BB, APB and TA muscles MEPs (motor evoked potentials) were performed as well. Results: In a group of patients we noticed a changes in the length and shape of the spinal cord but also spinal cord functions, already in the neutral position, even though there was no significant spinal cord compression. There were as well as healthy individuals elongation or shortening of PD and ZD during flexion and extension, There were, in contrast to...
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Spectral collocation methods in solid mechanics
Trnka, Ladislav ; Průša, Vít (advisor) ; Zeman, Jan (referee)
Spectral collocation methods are advertised as a powerful tool for a numerical so- lution of boundary value problems for ordinary as well as partial differential equations. The methods are based on a polynomial approximation, typically using Chebyshev poly- nomials. In one-dimensional setting, the properties of the methods are well known, and there exist several software packages implementing the methods. Our goal is to assess the applicability of spectral collocation methods in solving two-dimensional boundary value problems. We solve a classical problem in linearised two-dimensional elasticity, namely the deflection of a semi-infinite elastic medium subject to a surface load. The numerical results are compared to the analytical solution, which allows us to evaluate the performance of the given numerical method in solving boundary value problems in linearised elasticity. 1
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Novel hepatitis C virus proteins
Zeman, Jakub ; Vopálenský, Václav (advisor) ; Horníková, Lenka (referee)
The hepatitis C virus (HCV) is a major etiological agent of chronic liver diseases. More than 170 million people worldwide are chronically infected, and more than 100 thousand of them develop hepatocellular carcinoma a year. HCV is an enveloped, positive-sense single-stranded RNA virus (+ssRNA virus) of the family Flaviviridae. Its genome is translated to produce a single polyprotein precursor that is further processed by cellular and viral proteases to form 10 viral proteins. Moreover, there is another protein encoded in an alternative reading frame. Two alternative translation mechanisms have been proposed for expression of this alternative reading frame protein (ARFP): a frameshift mechanism and translation initiating from internal start codons. Despite ten years of research its role in vivo is not yet explained. It appears that secondary structures in the core encoding region of HCV genome but not ARFP expression are required for robust viral translation and replication. The results of recent studies suggest that mutations distorting these structures may result not only in slowing down the viral cycle but also in a brand new and utterly unusual serological profile in patients as well as an increased level of expression of ARFP.
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Matematické modelování magnetosriktních látek
Vermach, Lukáš ; Kružík, Martin (advisor) ; Zeman, Jan (referee)
4 Title: Mathematical modeling of magnetostrictive materials Author: Lukáš Vermach Department: Mathematical Institute of Charles University Advisor: Priv.-Doz. Dr. habil. RNDr. Martin Kružík Ph.D., Institute of Information Theory and Automation, Academy of Sciences of the Czech Republic Advisor's e-mail address: kruzik@utia.cas.cz Abstract In the present work we introduce an isotermic mathematical model of ferromagnetic shape memory alloys (FSMAs). FSMAs are a special class of magnetostrictive materials, i.e. materials which deform their shape on account of external magnetic field or which change magnetization as a consequence of strain. This property originates from phase transformations that occur within the material when being exposed to external loading. First, the stationary model of FSMA is formulated. The thermodynamical potential is composed (Helmholz free energy) and its non-quasiconvexity is discussed. The quasicon- vexification is performed via the relaxation theory, i.e. quasiconvex envelope construction. For such a model the existence theory is built. Then, taking advantage of the stationary case the evolutionary model is developed. The attention is drawn to hysteresis, which arises from energy dissipation. The time discretization leads to a sequence of hysteresis-modified stationary problems (the...
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Factors causing spatial distribution of ant nest
Zeman, Jiří ; Frouz, Jan (advisor) ; Holec, Michal (referee)
We observed the distribution in the large complex of the interrelated nests of Formica polyctena ant species on the locality Polánka near Mladá Vožice. In GIS we studied which factors affect spatial distribution of the F. polyctena anthills via diskriminant analysis. Totally we maped 244 nests. The main factors affecting the distribution of ant nests are existence of open areas in the forest (paths and openings) and the position of another anthills. The anthills indicate the cluster spacing. Anthills in the openings are smaller than those in the highwood.
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