2021, Vol. 23

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Now showing 1 - 5 of 12
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    Schopnosti dekódování videa jednotlivých modelù jednodeskového počítače Raspberry Pi
    (International Society for Science and Engineering, o.s., 2021-04-12) Benedikt, Jan
    The subject of the article is a comparison of selected generations of a single-board Raspberry Pi computer and their capabilities during the playback of multimedia video content. In the experimental measurement, four codecs were selected, which are currently the most used or the emerging standard. The specific codecs selected were AVC (Advanced VideoCoding) (H.264), HEVC (High Efficiency Video Coding) (H.265 ), AV1 (AOMedia Video 1) and VP9 (Video Predicator version 9). The test video files were generated in seven different resolutions (240p, 360p, 480p, 720p, 1080p, 1440p, and 2160p), with each resolution further subdivided into files of 24, 30, and 60 frames per second. Thanks to hardware support for decoding AVC and HEVC codecs, the 4B model showed the highest performance. The results showed that the slowest decoding of the video file occurred with the oldest model 2B. In contrast, the 4B model was able to decode video files the fastest.
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    Návrh vysokootáčkového asynchronního motoru
    (International Society for Science and Engineering, o.s., 2021-07-13) Klíma, Petr; Ondrůšek, Čestmír; Mach, Martin
    This paper describes the design procedure of a 3 kW 180 000 rpm high-speed induction motor. It shows the connection between the electromagnetic a mechanical design of this type of machine. The focus of the paper are the rotor issues, which are mainly the considerable centrifugal forces, magnetic skin effect and bending shapes.
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    Techno-economic comparison of various renewable energy sources for hybrid system implementation
    (International Society for Science and Engineering, o.s., 2021-08-17) Cerny, Tomas; Ptacek, Michal
    The current trends in electro-energetics indicate, that due to depletion of fossil fuels and the need of CO2 emission reduction, there is and will be a substantial development in the fields of renewable energy sources, decentralization and accumulation of electricity using battery energy storage systems in the near future. Along with the increasing power demand and penetration of renewables into electric grids, there is a need for energy mix expansion. Hybrid renewable energy sources (HRES) combine several renewables and energy storage into one system and can be used for micro-grid implementation for off-grid application or on-grid. The article is focused mostly on off-grid systems and provides an information about current state of renewable energy sources applications in HRES with techno-economic evaluation of net present cost and levelized cost of energy.
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    Analýza zdrojů nevyžádané pošty českého e-mailového serveru
    (International Society for Science and Engineering, o.s., 2021-04-23) Caha, Tomáš
    The paper deals with unsolicited electronic mail. The aim is to identify differences between the local and the global view of spam sources. The analysis of data from the Czech email server about email spam collected for several periods of three years was conducted. The geographical location of the sender’s Internet Protocol (IP) address was analyzed. Furthermore, a language of unsolicited messages was estimated. The language estimation was based on the subject of messages. Results were compared with IP addresses listed in global lists as sources of email spam. For the Czech Republic, differences were found both in the countries and in their share in this activity.
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    Návrh zpracování datasetu u metod strojového učení pro odhalování útoků v oblasti informační bezpečnosti
    (International Society for Science and Engineering, o.s., 2021-06-29) Slunský, Tomáš
    The article analyzes current vulnerabilities of web applications and how to effectively prevent them using machine learning methods. The article also reflects on the current events through a vulnerability that appeared at the end of 2020 and negatively affected a number of websites in the Czech Republic. The aim of the paper will be to demonstrate the specific vulnerability, analyse its potential impact and propose improvements to existing methods for detecting attacks using machine learning techniques. The proposed solution is based on knowledge of web applications and frameworks implemented in PHP (Hypertext Preprocessor).