Dijagnostika vibracija lista kružne pile uz pomoć davača pomaka

The paper deals with problems of the circular sawblade vibration. In the introductory part, theoretical bases are summarized to determine the form of vibrations and critical and resonant rotational frequency. A diagnostic method is proposed for the direct measurement of amplitudes of a circular sawblade by displacement sensors with the subsequent Fast Fourier Transform (FFT) analysis. This method with the spectral analysis of a signal in the time area makes possible to determine the size and shape of vibration of a circular sawblade with respect to usability/applicability under operational conditions. Unlike standard methods, when the sawblade is excited by external sources, natural vibrations are used such as disk deformations and the dynamic unbalance of a circular sawblade, effects of chucking/gripping and machine vibration and, last but not least, the disk and sawn wood interaction.U radu se obrađuje problem vibracija lista kružne pile. U uvodnom dijelu daju se teorijske osnove za određivanje oblika vibracija te kritične i rezonantne frekvencije vrtnje. Predložena je dijagnostička metoda za neposredno mjerenje amplitude vibracija lista kružne pile uz pomoć davača pomaka i nakon toga uz pomoć Fast Fourierove (FFT) analize dobivenih podataka. Ta metoda sa spektarskom analizom realnog signala omogućuje određivanje veličine i oblika vibracija lista kružne pile uzimajući u obzir uporabljivost/primjenjivost metode u radnim uvjetima. Nasuprot standardnoj metodi, koja podrazumijeva pobudu lista pile na vibriranje vanjskim izvorima, u prezentiranoj se metodi iskorištavaju prirodni izvori pobude kao što su deformacija diska pile i dinamička neizbalansiranost, utjecaj vibracija stroja te interakcije lista kružne pile i obratka

The possibilities of using optical properties measurement methods for TBC research

The main task of the thermal barrier coatings (TBC) is to protect the base material from the effects of high temperatures and thermal shocks. Heat transfer through the multilayered structure of TBC is performed by conduction and radiation. It is important to know not only the thermal conductivity and specific heat capacity of individual materials, but also the reflectivity, transmissivity and emissivity of the individual layers and the entire structure of TBC. Please click Additional Files below to see the full abstract

The utilization of laser thermal testing with thermographic measurement for TBC lifetime performance evaluation

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PETROLOGIE A RUDNÍ PARAGENEZE VÁPENATOSILIK ÁTOVÝCH HORNIN KEPRNICKÉ SKUPINY SILESIKA

The calc-silicate rocks (skarns) of the Keprník Group in the Silesicum were influenced by regional metamorphism in the amphibolite facies and contain mineral assemblage : diopside - quartz - plagioclase - calcite - dolomite - titanite ± hornblende ± microcline ± biotite (phlogopite) ± chlorite ± minerals of zoisite-epidote group. From the accessoric minerals are current rutile, apatite, zircon and locally ore minerals. All present calcareous inosilicates and phyllosilicates have Mg-rich and Fe-poor composition.The sulphidic mineralization connected with calc-silicate rocks (localities Hučivá Desná, Mlýnky a Bezný) is represented by two different ore types. The first ore type of disseminated or cluster structure are Fe-sulphides (pyrrhotite, pyrite) such as common accessories in rocks at localities Hučivá Desná and Mlýnky. Only at locality Bezný were founded Fe-sulphides of massive structures and rarely implications of banded structures too. The second ore type mainly of cluster structure is represented by galena with sphalerite, locally accompanied by pyrite and chalcopyrite. This ore type is adherent to the carbonate parts (in Hučivá Desná) or quartz veins (in Mlýnky) which are connected with calc-silicate rocks. The succession of ore minerals generally conforms with the sequence of sulphides in metamorphogene ores. Genesis of individual ore assemblages is similar in all localities. Ore mineralizations were probably connected with volcano-sedimentary protoliths of rocks and with later metamorphogene and hydrotermal processes which caused their mobilization and subsequent accumulation

Raman bands in microwave plasma assisted chemical vapour deposited films

Raman spectroscopy is employed to characterize thin diamond films deposited by microwave plasma assisted chemical vapour deposition technique using a gas mixture of methane and hydrogen. The surface morfology of the films was analyzed by scanning electron microscopy. We have identified submicron crystals on (100) facets of diamond crystals which gave rise to bands in the Raman spectrum centred at 1170 and 1456 cm-1

A Real Model of a Micro-Grid to Improve Network Stability

This paper discusses the smart energy model of a smart grid using a significant share of renewable energy sources combined with intelligent control that processes information from a smart metering subsystem. An algorithm to manage the microgrid via the demand-response strategy is proposed, accentuating the requirement that the total volume of energy produced from renewable sources is consumed. Thus, the system utilizes the maximum of renewable sources to reduce CO2 emissions. Another major benefit provided by the algorithm lies in applying the current weather forecast to predict the amount of energy in the grid; electricity can then be transferred between the local and the main backup batteries within the grid, and this option enables the control elements to prepare for a condition yet to occur. Individual parts of the grid are described in this research report together with the results provided by the relevant algorithm