Design of Hydraulic Drive of Wood Splitting Machine

Import 02/11/2016MOCEK, L. Návrh hydraulického pohonu štípače dřeva: bakalářská práce. Ostrava: VŠB – Technická univerzita Ostrava, Fakulta strojní, Katedra hydromechaniky a hydraulických zařízení, 2016, 42s. Vedoucí práce: doc. Ing. Martin Vašina, Ph.D. Cílem této bakalářské práce je návrh a výpočet hydraulického horizontálního štípacího stroje na zpracování dřevěné kulatiny podle zadaných parametrů. Návrh hydraulického štípacího stroje by měl usnadnit náročnou fyzickou práci spojenou s přípravou dřeva na následné topení. Před návrhem samotného stroje je potřeba si zvolit maximální rozměry štípané kulatiny, které jsou průměr 0,5m a délka 0,5m. Tyto rozměry jsou ideální volbou pro vytápění v kamnech nebo v krbu. Nejprve jsou zde rozebrány jednotlivé vyráběné typy štípaček, poté následuje zvolení druhu štípaných dřevin. Další část se zabývá návrhem a výpočtem jednotlivých hydraulických komponentů. Na závěr je provedena kontrola pevnosti pístní tyče.MOCEK, L. Design of Hydraulic Drive of Wood Splitting Machine . Ostrava: VŠB – Technical University of Ostrava, Faculty of Mechanical Engineering,Department of Hydromechanis and Hydraulic Equipment, 2016, 42s. Thesis head: doc. Ing. Martin Vašina, Ph.D. The aim of my bachelor thesis is design and calculation of hydraulic drive of wood splitting machine according to given parameters. Desing of this machine should make the hard work related to preparation of wood for heating easier. First of all it is necessary to choose maximal parametres of wood, whose diameter is usually 0,5 metres and the lenght is 0,5 metres.These limits are ideal choice for heating in tiled stoves or in fireplace.I also describe the particular types of wood splitting machines; followed by the choice of different types of wood there. Then, I try to solve design and calculation of particular hydraulic components. Finally there is a review of strenght of piston bar.338 - Katedra hydromechaniky a hydraulických zařízenívelmi dobř

Flying robot for geophysical purposes

Cílem této práce je navrhnout konstrukční řešení pro dálkově řízený létající stroj a navrhnout způsob jeho řízení. Práce se zabývá obecným způsobem, jak zkonstruovat létající stroj se svislým startem a konkrétním řešením konstrukce.The aim of this work is to propose a construction solution for remote controlled flying machine and to propose way of its management. The work deals with the general way to construct a flying machine with vertical start and concrete solution for construction.

Individual Professional Practice in the Company

Tato práce reprezentuje průběh individuální odborné praxe ve firmě ITA spol. s.r.o. sídlící v Ostravě, kde jsem pracoval na pozici programátor. Součástí práce je profil firmy ITA spol. s.r.o., pracovní zařazení, popis zadaných úkolů, na kterých jsem pracoval v průběhu praxe a jejich řešení. Závěrem jsou v této práci uvedeny znalosti získané studiem, které jsem během praxe uplatnil. Znalosti získané během praxe, a celkové zhodnocení praxe a jejího přínosu.The work represent process of individual professional practise in firm ITA spol. s.r.o. based in Ostrava, where I worked on position programer. Part of the work is ITA spol. s.r.o. busines profile, job title, task descriptions that I have got during my practice, and its solutions. In fine, knowledge retrieved by the studies that I succesfully applied in my practice process as well, are also mentioned. The same goes for knowledge retrieved during the practice, and estimation of the practice and its benefit en masse.460 - Katedra informatikyvýborn

Evidence for Miocene subduction beneath the Alboran Sea (Western Mediterranean) from 40Ar/39Ar age dating and the geochemistry of volcanic rocks from holes 977A and 978A

Volcanic pebbles in gravels from Sites 977 and 978 in the Alboran Sea (western Mediterranean) were dated (using the 40Ar/ 39Ar single-crystal laser technique) and analyzed for their major- and trace-element compositions (determined by X-ray fluorescence and inductively coupled plasma-mass spectrometry). The samples range from basalts to rhyolites, and belong to the tholeiitic, calc-alkaline, and shoshonitic series. Single-crystal and step-heating laser 40Ar/39Ar analyses of plagioclase, sanidine, biotite, and amphibole phenocrysts from basaltic to rhyolitic samples indicate that eruptions occurred between 6.1 and 12.1 Ma. The age data conform to the stratigraphy and agree with microfossil ages, when available. The major-element and compatible trace-element data of samples with H2O < 4 wt% show systematic variations, consistent with fractionation of the observed phenocryst phases (plagioclase, olivine, clinopyroxene, magnetite, hornblende, quartz, and biotite). The incompatible-element patterns formed by normalizing to primitive mantle for all samples show spiked patterns with peaks generally at mobile elements and troughs at immobile elements, in particular Nb and Ta. The calc-alkaline affinities and the incompatible-element systematics are characteristic of subduction zone volcanism, which indicates that subduction occurred beneath the eastern Alboran from 6 to at least 12 Ma. We propose that the change in chemistry from calc-alkaline and potassic to sodic compositions between 5– 6 Ma reflects detachment of the subducting slab. Uplift of the Strait of Gibraltar, associated with this detachment, could have caused the Messinian Salinity Crises

Investigations of Protective Coatings for Castings of High-manganese Cast Steels

When cast steel castings are made in moulding sands on matrices of high-silica sand, which has a low fire resistance the problem of theso-called chemical penetration is distinctly visible. Whereas this effect appears to a small degree only when moulding sand matrices are of chromite, zircon or olivine sands. Therefore in case of making castings of high-manganese cast steel (e.g. Hadfield steel) sands not containing free silica should be applied (e.g. olivine sand) or in case of a high-silica matrix protective coatings for moulds and cores should be used. Two protective coatings, magnesite alcoholic (marked as coating 1 and coating 2) originated from different producers and intended for moulds for castings of the Hadfield steel, were selected for investigations. Examinations of the basic properties were performed for these coatings: viscosity, thermal analysis, sedimentation properties, wear resistance. In order to estimate the effectiveness of protective coatings the experimental castings were prepared. When applying coating 1, the surface quality of the casting was worse and traces of interaction between the casting material (cast steel) and the coating were seen. When protective coating 2 was used none interactions were seen and the surface quality was better

Projected Krylov methods for solving non-symmetric two-by-two block linear systems arising from fictitious domain formulations

The paper deals with the solution of large non-symmetric two-by-two block linear systems with a singular leading submatrix. Our algorithm consists of two levels. The outer level combines the Schur complement reduction with the orthogonal projectors that leads to the linear equation on subspaces. To solve this equation, we use a Krylov-type method representing the inner level of the algorithm. We propose a general technique how to get from the standard Krylov methods their projected variants generating iterations on subspaces. Then we derive the projected GMRES. The efficiency of our approach is illustrated by examples arising from the combination of the fictitious domain and FETI method

High-efficiency optical pumping of nuclear polarization in a GaAs quantum well

The dynamic polarization of nuclear spins by photoexcited electrons is studied in a high quality GaAs/AlGaAs quantum well. We find a surprisingly high efficiency of the spin transfer from the electrons to the nuclei as reflected by a maximum nuclear field of 0.9 T in a tilted external magnetic field of 1 T strength only. This high efficiency is due to a low leakage of spin out of the polarized nuclear system, because mechanisms of spin relaxation other than the hyperfine interaction are strongly suppressed, leading to a long nuclear relaxation time of up to 1000 s. A key ingredient to that end is the low impurity concentration inside the heterostructure, while the electrostatic potential from charged impurities in the surrounding barriers becomes screened through illumination by which the spin relaxation time is increased compared to keeping the system in the dark. This finding indicates a strategy for obtaining high nuclear spin polarization as required for long-lasting carrier spin coherence.Comment: 6 pages, 4 figure