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Výzkum vlivu množství argony na stabilitu proudu Ar-H-O plazmatu
Chumak, Oleksiy ; Kavka, Tetyana ; Hrabovský, Milan
The paper examines an effect of an argon amount on the thermal plasma jet generated from water/argon mixture in a dc arc plasma torch. In spite of an increase of plasma velocity with an addition of argon a decrease of plasma jet length is observed for bigger argon amount in the plasma. The investigation was based on an analysis of a jet structure based on imaging of the plasma jet by a CCD camera. Statistical processing of plasma jet photographs provided information about a jet shape and its fluctuations space distribution. It was found that an argon amount increase caused significant intensification of the plasma jet fluctuations.
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Periodické vlastnosti převzorkovaných obrazů
Mahdian, Babak ; Saic, Stanislav
In recent years, due to the advent of high-performance commodity hardware and improved human computer interfaces, it has become relatively easy to create fake images. Modern, image processing software enables forgeries that are undetectable by the naked eye. Typically, to create high quality and consistent forgeries, several types of tampering techniques are employed simultaneously. One of the most often used techniques is resampling. When two or more images are spliced together, in order to create a consistent tampering, almost always geometric transformations such as scaling or rotation are needed. In this work we propose an effective method to automatically detect resampled portion of images. Generally, resampling is based on an interpolation procedure. We study specific periodic properties presence in interpolated signals and use this for our detection method. We demonstrate our results on several examples.
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Skyté periodicity v interpolovaných signálech a jejich derivacích
Saic, Stanislav ; Mahdian, Babak
Many applications like, texture analysis, image registration, etc., are based on interpolation. Therefore, without the detailed knowledge of how the statistics of the signal is changed by the interpolation process, applications based on statistical approaches working with interpolated signals or with their derivatives can yield miscalculations and unexpected results. Therefore a detailed knowledge about the changes brought into the signal by interpolation could be critical. Sometimes, there exists a need to examine whether a signal has been interpolated.
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Statistické zpracovani obrázku plazmatického prouděni pro vizualizace nestabilit
Chumak, Oleksiy
The structure and stability of a thermal plasma jet were studied on the basis of statistical analysis of images of a plasma jet taken by a fast shutter camera. The space distribution of the mean value and the standard deviation of image brightness were evaluated from a sequence of images. The short exposure time ensured imaging of the momentary state of the jet while analysis of a sequence of images provided information about jet fluctuations. Effect of arc current was investigated. Arc power increase led to higher fluctuations of the jet, although it caused increase of the jet length.
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Simulink jako nástroj pro vývoj rekonfigurovatelných aplikací
Kovář, Bohumil ; Schier, Jan ; Zemčík, P. ; Herout, A. ; Beran, V.
Our paper focuses on rapid prototyping and configuration tools for an embedded system. It will present novel concept of an image processing architecture based on interconnection of a programmable logical chip (FPGAs) with digital signal processor (DSP). In the paper, we shall outline a configuration tool tailored towards systems combining both DSP and FPGA, based on a configuration/programming scripting language and with a complex library of functions and modules for selected applications in signal and video processing.
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