Influence of metal vapours on radiation characteristics of air arc plasmas

This paper deals with the evaluation of radiation properties of air arc plasma with various admixtures of Cu, Ag, and Fe, respectively. Under assumption of isothermal plasma cylinder, the net emission coefficients were calculated for various arc radii as a function of the plasma temperature up to 30000K. For plasma with prescribed temperature profile, the equation of radiation transfer was solved in the P1approximation, and the radiation flux and its divergence were calculated

Numerically optimized band boundaries of Planck mean absorption coefficients in air plasma

Radiation heat transfer plays an important role in the energy balance of plasma in an electric arc and its accurate prediction is essential for the development of new electrical devices. Unfortunately, a very complex spectrum of the absorption coefficient makes accurate radiation heat transfer calculations a very challenging task, especially with complex geometries. Numerical approximation of the absorption coefficient is therefore commonly used to reduce computing demands. This paper presents our contribution to the topic of computing requirements reduction, namely the problem of frequency band selection for mean absorption coefficients (MACs). We show that, with the proper band distribution and averaging method, even a very low number of bands can be sufficient for an accurate approximation of the real radiation heat transfer. The band selection process is based upon numerical optimization with a mean value of each band being calculated as a line limited Planck MAC. Both the line limiting factor and associated characteristic plasma absorption length are investigated in detail and an optimal value equal to the three plasma radii is proposed. Tables for three bands mean absorption coefficients in air at the pressure of 1 bar and temperature range spanning from 300 K to 30 kK are included in this paper. These tables serve as input parameters for a fast evaluation of radiation transfer using either the P1 or discrete ordinates method (DOM) approximation with satisfactory accuracy

Reconstruction proposal of small water power station on Berounka river

Cílem práce je návrh rekonstrukce malé vodní elektrárny na řece Berounce. Úvodní část je zaměřena na seznámení s problematikou získávání elektrické energie z vodních zdrojů; dále je popsán současný stav elektrárny se současnými výkony dodávanými do distribuční sítě a možnostmi získávání informací o aktuálním výkonu a předpokládaném průtoku vody. Následuje návrh rekonstrukce, který se snaží maximálně využít povolené hydrologické poměry dané lokalitou. Pro navrhované řešení je vypočtena teoretická výroba elektrické energie generované novou elektrárnou. Poslední část hodnotí navrhované řešení po stránce ekologické, energetické a ekonomické.ObhájenoThe aim of this thesis is to design a reconstruction of a small hydroelectric power plant on the river Berounka. The introductory part of the thesis is focused on getting acquainted with the issue of obtaining electricity from a water sources. Furthermore, the present state of the power plant is described with the outputs supplied to the distribution network and the possibilities of obtaining information on the present output and predictingthe water flow. Next, the paper focuses on the design of the reconstruction, where the effort is to make maximum use of the permitted hydrological conditions of the site. For the proposed solution the theoretical production of electricity generated by the new power plant is calculated. The last part evaluates the proposed solution in ecological, energy and economic terms

Modern solution of Pragotron clock

Cílem této práce je sestavit ovládací jednotku pro staré překlápěcí hodiny Pragotron IPJ-0612. Úvodní část práce je zaměřená na seznámení s ovládáním mechanismu hodin. Dále jsou zmíněné možnosti získávání informace přesného času a popis získávání přesného času pomocí radiového signálu DCF77. Následně se práce zaměřuje na získání informace o natočení překlápěcích listů hodin, pro které byly vytvořeny speciální vačkové hřídele. V další části práce je popsána implementace řízení hodin pomocí základního mikrokontroleru od firmy Arduino a následně sofistikovanějšího mikrokontroleru od firmy ST. Poslední část zobrazuje umístění hardwaru do instalačních krabic a jejich propojení.ObhájenoThe aim of this work is to assemble the control unit for the old Pragotron clock IPJ-0612. The introductory part of the thesis is focused on the control of the clock mechanism. At the next part of the work, the possibilities of transmittion of exact time information are mentioned, and the process of time-sync request of the radio signal DCF 77 is described. The following section is focused on obtaining information about the tilting sheets rotation inside the clock, therefore the special camshafts were created. The next part describes the implementation of clock control by using basic microcontroller made by Arduino and then more sophisticated microcontroller made by ST. The last part describes the location of the hardware in the installation boxes and their connection

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Data Warehouse, Scripting Language, Data Pump, Data Mining

The bottleneck of a data warehouse implementation is the ETL (extraction, transformation, and load) process, which carries out the initial population of the data warehouse and its further (usually periodical) updates. There is a number of software products supporting the OLAP analysis. However, the ETL process implementation is not repeatable in a significant way. This paper reports on a research of a model-based data transformation applicable to data warehouse population and updates. The ETL process is based on a metadata repository, which contains data models of the data sources, the target data warehouse model, and the correspondence among them

Progress in SumatraTT: ILP Connectivity and More New Features

SumatraTT (Transformation Tool) is a universal data preprocessor allowing to access data stored in various types of sources (e.g. plain text, SQL etc.). We briefly review the concept of the system and summarize its recent developments. ILP connectivity is overviewed, consisting of a fine-tunable Prolog data driver and a special template script creating data for a specific ILP system. Moreover we inform on some newly added features consisting of new data interfaces, scripting features, and templates. After a brief touch upon near-future plans, we finally discuss some questions typically arising at the first usage of SumatraTT. 1 THE CONCEPT OF SUMATRA SumatraTT (Transformation Tool) is a metadata-driven, platform independent, extensible, and universal dat

SumatraTT-predzpracovani dat.

Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

SumatraTT: Towards a universal data preprocessor

In the practice of data mining (DM) and data warehousing (DWH), real-life data arrive in various different formats, and without putting them into an acceptable shape, even the most intelligent DM/DWH tool would be useless. SumatraTT (Transformation Tool) is an original universal data pre-processing tool allowing to access and transform data stored in various types of datasources (e.g. plain text, SQL etc.). We briefly review the concept of the system and summarize its recent developments. The paper briefly overviews the connectivity with inductive logic programming (ILP) systems and then informs on more recently added features consisting of new data interfaces, scripting features, and templates. The usage of Sumatra TT on an example application is shortly demonstratied. After a brief touch upon near-future plans, we finally discuss some questions typically arising at the first usage of SumatraTT

Vliv par kovů na radiační charakteristiky obloukového plazmatu vzduchu

This paper deals with the evaluation of radiation properties of air arc plasma with various admixtures of Cu, Ag, and Fe, respectively. Under assumption of isothermal plasma cylinder, the net emission coefficients were calculated for various arc radii as a function of the plasma temperature up to 30 000 K. For plasma with prescribed temperature profile, the equation of radiation transfer was solved in the P1 approximation, and the radiation flux and its divergence were calculated.Článek se zabývá výpočtem radiačních vlastností obloukového plazmatu vzduchu s různými příměsemi Cu, Ag a Fe. Za předpokladu izotermálního válcového plazmatu byl vypočítán koeficient střední emise pro různé poloměry oblouku jako funkce teploty plazmatu až do teplot 30 000 K. Pro plazma s předepsaným tepltním profilem byla řešena rovnice přenosu záření v P1 aproximaci a byl vypočítán radiační tok a jeho divergence