2001/2

Browse

Recent Submissions

Now showing 1 - 5 of 8
  • Thumbnail Image
    Item
    Identifying the Deterministic Chaos by Using the Lyapunov Exponents
    (Společnost pro radioelektronické inženýrství, 2001-06) Kvarda, P.
    This paper presents an investigation of deterministic chaos. The modified Colpitts oscillator is used as an example of deterministic chaos in electronic circuits. The most known quality of deterministic chaotic systems the positive Lyapunov exponent is used for investigation the chaotic Colpitts oscillator.
  • Thumbnail Image
    Item
    Ultrasonic Approach to Nonivasive Temperature Monitoring During Microwave Thermotherapy
    (Společnost pro radioelektronické inženýrství, 2001-06) Novak, P.; Zuna, I.; Pousek, L.; Vrba, J.
    Microwave thermotherapy (MT) is an oncological treatment. At present the invasive thermometer probes are clinically used for temperature measuring during an MT. Any invasive handling of tumors is of high-risk. A new possible method of noninvasive monitoring of temperature distribution in tissue has been developed. An MT treatment of the experimentally induced pedicle-tumors of the rat was prepared. For 100 rat samples a strong correlation between the mean gray level in the ROIs in the ultrasound pictures and the invasively measured temperature in the range 37-44 °C was found. The correlation coefficient of the mean gray level and the invasively measured temperature is 0.96a0.05. A system for representation of changes of spatial temperature distribution of the whole tumor during MT is presented.
  • Thumbnail Image
    Item
    Impulse Detectors for Noised Sequences
    (Společnost pro radioelektronické inženýrství, 2001-06) Lukac, R.
    This paper is focused on a problem of impulse detection in the dynamic image environments corrupted by impulse noise. Using a proposed architecture that includes an impulse detector and the median filter, the effective methods can be designed. Thus, the image points are classified into two classes such as a class of noise free samples and a class of noised image points. In the case of impulse detection the estimate is performed by a median filter whereas a noise free sample is passed on the output without the change i.e. system works as an identity filter.
  • Thumbnail Image
    Item
    Digital Watermarking in Wavelet Transform Domain
    (Společnost pro radioelektronické inženýrství, 2001-06) Candik, M.; Matus, E.; Levicky, D.
    This paper presents a technique for the digital watermarking of still images based on the wavelet transform. The watermark (binary image) is embedded into original image in its wavelet domain. The original unmarked image is required for watermark extraction. The method of embedding of digital watermarks in wavelet transform domain was analyzed and verified on grey scale static images.
  • Thumbnail Image
    Item
    The Modified Node Voltage Method as Tool for Calculation of Network Functions and Sensitivities
    (Společnost pro radioelektronické inženýrství, 2001-06) Valsa, J.
    The paper deals with the well-known modified node voltage method that is generally used for formulation of system equations in universal network simulation programs. It shows very efficient ways if utilizing this type of equation formulation for evaluation of network transfer functions and their sensitivities to variations of element parameters. The described procedures can be used very effectively namely in connection with some matrix oriented mathematical program like for instance MATLAB. Several illustrative examples support the explanation of the methods described in the paper.