Ústav radioelektroniky


Recent Submissions

Now showing 1 - 5 of 223
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    Novel voltage Multiplier/Divider-based active square law detector for heartbeat measurement
    (ELSEVIER SCI LTD, 2024-02-28) Šotner, Roman; Polák, Ladislav; Jeřábek, Jan; Langhammer, Lukáš; Freeborn, Todd
    This paper describes a novel active voltage detector that is capable of processing analog signals with levels from units of mV up to 250 mV. An advantage of the proposed circuit is that the relationship between output voltage and input level is not linear but quadratic, which increases the sensitivity when processing low-level signals. The presented solution has tuning parameters for correction or intentional shift of internal DC offset and electronic control of the output signal gain level. The application example presents detection of beats per minute (BPM) in the range of 6-300 BPM, which corresponds to a frequency range of 0.1-5 Hz. The advantage of the presented solution is that the output of the circuit is directly a digital signal compatible with TTL levels, so there is no need for any analog to digital converter to produce a digital signal for further processing.
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    Emulating Multimemristive Behavior of Silicon Nanowire-Based Biosensors by Using CMOS-Based Implementations
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2024-03-15) Bhardwaj, Kapil; Semenov, Dmitrii; Šotner, Roman; Chen, Junrui; Carrara, Sandro; Srivastava, Mayank
    The research presented in this article draws inspiration from previous efforts aimed at replicating the functions of various solid-state memristors using a variety of materials. The memristor circuit emulator serves as a cost-effective tool for circuit designers, enabling them to experiment with the diverse electrical characteristics of corresponding solid-state memristors. This article specifically focuses on the circuit-based emulation of silicon nanowire (SiNW) known for its effectiveness in biosensing applications. First, a fully floating memristor emulator has been presented based on a voltage differencing current conveyor (VDCC) and an operational transconductance amplifier (OTA)-controlled resistor, along with a grounded capacitance. Furthermore, the proposed memristor emulator was realized by employing integrated cells based on the discussed technology, and the simulation/experimental results are presented and analyzed. The experiments also confirmed the nonvolatile behavior of the realized memristor. The results demonstrate that the real-time implementation of the proposed emulator can accurately generate hysteretic behavior in both incremental and decremental memristive mode. Finally, the incremental and decremental pinched hysteresis loop (PHL) responses generated by the proposed emulator have been utilized to replicate the various types of memristive responses offered by SiNW by adding a simple extension to the circuit.
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    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.
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    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.
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    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).