Computer modeling of meta-materials

Tato diplomová práce se zabývá metamateriálovými strukturami. Což jsou periodické struktury, které mohou mít permitivitu nebo permeabilitu, popřípadě oba tyto parametry, záporné. Je provedeno testování na třech základních strukturách: Split Loop Array; Spiral Array a Double Spiral Array. Pro každou strukturu je vytvořen disperzní diagram a jsou sledovány S – parametry. Testování je prováděno v komerčním software Ansoft High Frequency Structure Simulator a CST Microwave Studio. Sledují se zádržná pásma těchto struktur a kdy se struktura chová jako left – handed medium nebo right – handed medium. Výsledky jsou porovnány s výsledky v literatuře.The diploma thesis deals with metamaterial structures. Metamaterials are periodic structures, which have got permittivity or permeability, eventually both parameters, negative. Test is applied on three basic structures: Split Loop Array; Spiral Array a Double Spiral Array. For each structure is made dispersion diagram and are monitored S – parameters. Test is run in Ansoft High Frequency Structure Simulator and CST Microwave Studio software. Are monitored bandgaps and when structure is as left – handed medium or right – handed medium. Results are compared with results in literature.

Experimental analysis of the sewing machine

This paper is concerned with experimental analysis of the behaviour of mechanisms of sewing machines. There has been carried out mapping of the sound field in the vicinity of the sewing machine, in order to locate the source of impact loading and to establish the overall hygienic loading of the machine. Based upon this analysis, the acceleration of the needle bars has been measured. These two measuring have led to the conclusion that it is the cam mechanism which most contributes to the noise and impact loading. © The Authors, published by EDP Sciences, 2017

Finding the optimal setting of the sewing needle transfer mechansm using simulation software

The paper is concerned with an analysis and optimisation of the needle transfer mechanism by means of the software Pro/Engineer Wildfire 4 with the aim to obtain a reduction of needle wear. An optimisation of parameters of the setting mechanism that influence the moment of release of the needle during its transfer from one needle bar to the other has been carried out. As a result the optimal setting of the needle transfer mechanism was found. Modifications of the design of the needle transfer mechanism were proposed which are leading to improved force effects in the gripping of the needle. The results have been experimentally verified by the long-term operation of a functional model

Magnetic and Magneto-Optical Properties of Fe75-xMn25Gax Heusler-like Compounds

Fe75-xMn25Gax Heusler-like compounds were investigated in a wide range of Fe/Ga ratios while keeping the Mn content constant and equal 25 at% in order to elucidate the interplay between magnetic properties and composition. Materials were prepared by arc-melting from pure elements and subsequently annealed. Experimental investigations were focused on magnetization behavior in a wide temperature range from 4 to 1000 K and magnetic field up to 9 T. Optical and magneto-optical (MO) measurements were employed to shed more light on the magnetic state and electronic structure of investigated materials. Magnetization measurements indicated that in the vicinity of stoichiometry (Fe2MnGa) the compounds are ferro/ferrimagnetic, whereas the Fe-deficient compound is paramagnetic and at high Fe concentration the antiferromagnetic interaction prevails. Theoretical calculations of corresponding ordered and disordered stoichiometric compounds were carried out and compared to the experiment on the level of net magnetic moment as well as magneto-optical spectra. This comparison suggests that the Heusler crystal structure, L2(1), is not present even close to stoichiometry. Moreover, the comparison of density of states (DOS) for ordered and disordered structures allowed us to explain missing martensitic transformation (MT) in investigated materials

Měkkýši Hostýnských vrchů

This study deals with the molluscan fauna of the Hostýnské vrchy Hills (Central Moravia, Czech Republic). The main goal was to make a systematic inventory of the molluscan fauna in this area. Snails were collected in September 2010 by hand picking and litter sampling at selected sites. Final database was pooled with earlier published and unpublished data. In total, 85 terrestrial and 20 freshwater mollusc species were recorded at 56 study sites across the area during 2000–2010. Terrestrial snails Monachoides incarnatus, Punctum pygmaeum, Vitrina pellucida, and freshwater molluscs Pisidium casertanum, and Radix labiata were the most frequently recorded species. The land snails Daudebardia brevipes, Eucobresia nivalis, Vitrea transsylvanica, and Chondrula tridens are notable species from the local viewpoint. The clausilid Vestia ranojevici moravica, an endemic subspecies that colonized some regions of Moravia during the Holocene climatic optimum, is an iconic mollusc species in the area, deserving high conservation priority

Vodní měkkýši přírodní rezervace Horní Lužnice – revizní průzkum po více než 10 letech

The Lužnice River and its floodplain are protected in the Horní Lužnice Nature Reserve (Southern Bohemia, Czech Republic). The floodplain has a relatively natural character. Altogether 21 aquatic mollusc species were found at 40 sites. Lymnaea stagnalis, Physa fontinalis, Segmentina nitida and Planorbarius corneus belonged among the most often recorded species. Endangered Pisidium globulare was found. Non-native molluscs were not recorded. Only minimal changes were documented after the first research of this reserve, which was done more than 10 years ago

Frézování kalených povrchů vysokými rychlostmi

Import 20/04/2006Prezenční výpůjčkaVŠB - Technická univerzita Ostrava. Fakulta strojní. Katedra (346) obrábění a montáž