Ústav radioelektroniky

Browse

Recent Submissions

Now showing 1 - 5 of 219
  • Thumbnail Image
    Item
    Transformer-based Semantic Segmentation for Large-Scale Building Footprint Extraction from Very-High Resolution Satellite Images
    (Elsevier, 2024-03-09) Gibril, Mohamed Barakat A.; Al-Ruzouq, Rami; Shanableh, Abdallah; Jena, Ratiranjan; Bolcek, Jan; Zulhaidi Mohd Shafri, Helmi; Ghorbanzadeh, Omid
    Extracting building footprints from extensive very-high spatial resolution (VHSR) remote sensing data is crucial for diverse applications, including surveying, urban studies, population estimation, identification of informal settlements, and disaster management. Although convolutional neural networks (CNNs) are commonly utilized for this purpose, their effectiveness is constrained by limitations in capturing long-range relationships and contextual details due to the localized nature of convolution operations. This study introduces the masked-attention mask transformer (Mask2Former), based on the Swin Transformer, for building footprint extraction from large-scale satellite imagery. To enhance the capture of large-scale semantic information and extract multiscale features, a hierarchical vision transformer with shifted windows (Swin Transformer) serves as the backbone network. An extensive analysis compares the efficiency and generalizability of Mask2Former with four CNN models (PSPNet, DeepLabV3+, UpperNet-ConvNext, and SegNeXt) and two transformer-based models (UpperNet-Swin and SegFormer) featuring different complexities. Results reveal superior performance of transformer-based models over CNN-based counterparts, showcasing exceptional generalization across diverse testing areas with varying building structures, heights, and sizes. Specifically, Mask2Former with the Swin transformer backbone achieves a mean intersection over union between 88% and 93%, along with a mean F-score (mF-score) ranging from 91% to 96.35% across various urban landscapes.
  • Thumbnail Image
    Item
    Design of Building Blocks for Fractional-Order Applications with Single and Compact Active Device
    (IEEE, 2020-07-09) Šotner, Roman; Jeřábek, Jan; Langhammer, Lukáš; Koton, Jaroslav; Polák, Josef; Andriukaitis, Darius; Valinevicius, Algimantas
    This paper introduces new promising applications of VCA822 active device in the fractional-order design of two-ports including very simple and compact solutions of integrator, differentiator, low-pass and high-pass filter. Key feature of the designed circuits is their tunability controlled by current gain of VCA822 not available in case of solution with standard op-amps. Block (principal) structure of the device is explained in detail. PSpice simulation results of the designed circuits indicate usability of these ideas and also simple tunability of the application verified with a fractional-order constant phase element with the order alpha = 1/4.
  • Thumbnail Image
    Item
    Design of Electronically Adjustable Fractional Order Immittances Using Single Active Device
    (IEEE, 2020-07-09) Šotner, Roman; Jeřábek, Jan; Langhammer, Lukáš; Koton, Jaroslav; Andriukaitis, Darius; Merfeldas, Audrius
    This paper brings new approach for the design and construction of electronically adjustable immittance functions using single compact commercially available active device (VCAS22). Some of parameters of designed circuits can be controlled electronically thanks to type of used active device. Presented design uses RC approximants of fractionalorder element (order 1/4) in three application examples (fractional-order adjustable capacitance, inductance and frequency dependent negative resistor). PSpice simulations confirm expected behavior and tunability described by theoretical expressions (in wide band up to 10 MHz).
  • Thumbnail Image
    Item
    Novel Design Solution of Reconnection-less Electronically Reconfigurable Filter
    (IEEE, 2019-06-27) Langhammer, Lukáš; Šotner, Roman; Dvořák, Jan; Dostál, Tomáš
    The paper presents a new design solution of a reconnection-less electronically reconfigurable filter (no manual reconnection or topology change is necessary) offering all standard 2nd-order transfer functions (low pass, band pass, high pass, band stop and all pass). The filter can also provide high-pass and low-pass function with transfer zero (HPZ, LPZ), direct transfer and high-pass function of the 1st-order. The design is based on well-known operational transconductance amplifiers (OTAs) and adjustable current amplifiers (ACAs). Moreover, the electronic control of the pole frequency and quality factor of the filter are available. The proposal is verified by PSpice simulations using commercially available devices.
  • Thumbnail Image
    Item
    Practical Design of RC Approximants of Constant Phase Elements and Their Implementation in Fractional-Order PID Regulators Using CMOS Voltage Differencing Current Conveyors
    (SPRINGER BIRKHAUSER, 2019-03-18) Domanský, Ondřej; Šotner, Roman; Langhammer, Lukáš; Jeřábek, Jan; Psychalinos, Costas; Tsirimokou, Georgia
    This paper brings a practical and straightforward view on the design of circuit elements described by fractional-order dynamics known as the constant phase element (CPE) and their implementation in a novel structure of a PID (or PID in some literature) regulator based on fabricated CMOS voltage differencing current conveyors. Comparison of presented topology with known solutions indicates significant improvements regarding overall simplification, simpler electronic controllability of time constants, and having all passive elements in grounded form. Step-by-step design of the CPE as well as the PID regulator is supported by experiments with active devices fabricated using the C07 I2T100 0.7 m CMOS process (ON Semiconductor). Laboratory tests in frequency and time domain confirm the correct operation of the designed application and the accuracy of the derived results in comparison with the theoretical expectations.