2007/2

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Recent Submissions

Now showing 1 - 5 of 13
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    Analytical Modeling of Insulated Dipole Applicators for Interstitial Hyperthermia: a Review
    (Společnost pro radioelektronické inženýrství, 2007-06) Sagnard, Florence
    Microwave hyperthermia appears as an adjuvant technique to heat relatively small tumors in a minimally invasive way. As this technique is based on interstitial antennas, we propose a review of the physical phenomena involved in the radiation of such antennas in a dispersive medium, using the different analytical modeling developed since the 1970\'s. These modeling have been implemented in a freely available software tool, that will allow antenna designers and medical researchers to perform rapid parameter studies to further understand the role of the several parameters involved; this tool will also help the interpretation of results issued from numerical simulations. Simulation results associated with different antenna geometries are presented and compared to results obtained by several authors.
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    Segmentation Based Image Scanning
    (Společnost pro radioelektronické inženýrství, 2007-06) Pracko, Richard; Polec, Jaroslav; Hasenohrlova, Katarina
    The submitted paper deals with separate scanning of individual image segments. A new image processing approach based on image segmentation and segment scanning is presented. The resulting individual segments 1-dimensional representation provides higher neighbor pixel similarity than the 1-dimensional representation of the original image. This increased adjacent pixel similarity was achieved even without application of different recursive 2-dimensional scanning methods [4], such as Peano-Hilbert scanning method [1]. The resulting 1-dimensional image representation provides a good base for applying lossless compression methods, such as the entropic coding. The paper contains also results analysis of the traditional method scanned segment pixels and adjacent pixel differences from the entropy point of view. As these results indicate the lossy compression methods could be applicable using this approach as well and might improve the final results as confirmed by simple prediction algorithm results presented in this paper. More complex and sophisticated lossy compression algorithms application will be a part of the future work.
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    Automatic Classifiers for Medical Data from Doppler Unit
    (Společnost pro radioelektronické inženýrství, 2007-06) Malek, Jiri; Nouza, Jan; Klimovic, Tomas
    Nowadays, hand-held ultrasonic Doppler units are often used for noninvasive screening of atherosclerosis in arteries of the lower limbs. The mean velocity of blood flow in time and blood pressures are measured on several positions on each lower limb. This project presents software that is able to analyze such data and classify it in real time into selected diagnostic classes. It is also capable of giving a notice of some errors encountered during measuring. At the Department of Functional Diagnostics in the Regional Hospital of Liberec a database of several hundreds signals was collected. In cooperation with the specialist, the signals were manually classified into four classes. Consequently selected signal features were extracted and used for training a distance and a Bayesian classifier. Another set of signals was used for evaluating and optimizing the parameters of the classifiers. This paper compares the results of the software with those provided by a human expert. They agreed in 89 % cases.
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    DRM Transmitter with FPGA Device
    (Společnost pro radioelektronické inženýrství, 2007-06) Dobias, Pavel
    This paper presents the design and analysis of the OFDM modulator for Digital Radio Mondiale (DRM) standard. Attention is paid to the digital signal processing in FPGA devices. The system performs carrier modulation of the complex envelope of the DRM signal. It generates a phase modulated carrier and a magnitude signal that are used with a Pulse Step Modulation (PSM) transmitter. The system has been implemented by using VHDL language. Altera FPGA development kit with an additional board is used and functional tests and measurements are presented. Simulations evaluating the quality of the output signal were done.
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    Optimization of Transient Response Radiation of Printed Ultra Wideband Dipole Antennas (Using Particle Swarm Optimization Method)
    (Společnost pro radioelektronické inženýrství, 2007-06) Cerny, Petr; Mazanek, Milos
    In case of particular ultra wideband applications (i.e. radar, positioning, etc.), it is crucial to know the transient responses of antennas. In the first part of the paper, the optimization process searches for the dipole shape that accomplishes two required parameters i.e. a good matching and a minimal distortion. The particle swarm optimization method was used in the process of the dipole shape optimization. As a result, the optimized ultra wideband dipole is perfectly matched. Moreover, it minimally distorts the applied signal. The second part of the paper discusses the influence of the feeding circuit on radiating parameters and on the dipole antenna matching.