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Short-Term Entropy of Signal Energy Used for Effective Detecting of Weak Gunshots in Noisy Environments
(MDPI, 2024-07-30) Sigmund, Milan
Conventional gunshot detection systems can quickly and reliably detect gunshots in the area where the acoustic sensors are placed. This paper presents the detection of weak hunting gunshots using the short-term entropy of signal energy computed from acoustic signals in an open natural environment. Our research in this field was primarily aimed at detecting gunshots fired at close range with the usual acoustic intensity to protect wild elephants from poachers. The detection of weak gunshots can extend existing detection systems to detect more distant gunshots. The developed algorithm was optimized for the detection of gunshots in two categories of the surrounding sounds, short impulsive events and continuous noise, and tested in acoustic scenes where the power ratios between the weak gunshots and louder surroundings range from 0 dB to -14 dB. The overall accuracy was evaluated in terms of recall and precision. Depending on impulsive or noise sounds, binary detection was successful down to -8 dB or -6 dB; then, the efficiency decreases, but some very weak gunshots can still be detected at -13 dB. Experiments show that the proposed method has the potential to improve the efficiency and reliability of gunshot detection systems.
Spectral–Spatial Transformer-based Semantic Segmentation for Large-scale Mapping of Individual Date Palm Trees using Very High-resolution Satellite Data
(Elsevier, 2024-05-08) Al-Ruzouq, Rami; Gibril, Mohamed Barakat A.; Shanableh, Abdallah; Bolcek, Jan; Lamghari, Fouad; Hammour, Nezar Atalla; Al-Keblawy, Ali; Jena, Ratiranjan
Date palm plantations in the United Arab Emirates (UAE) are under threat from soil salinity, drought, and date palm weevils. Accordingly, monitoring and conserving date palms are crucial to preserving a vital component of the country’s agricultural heritage, economy, food security, and ecological balance. Previous studies have effectively identified date palm trees using RGB-based aerial and UAV imagery utilizing diverse deep learning methods. However, the utilization of very high-resolution satellite data for delineating individual date palm crowns remains unexplored due to the limited spatial resolution capabilities of existing satellite systems. This study primarily aimed to achieve precise and comprehensive mapping of date palm trees using WorldView-3 (WV-3) satellite data by leveraging the high representational power of the state-of-the-art vision transformers (ViT) in capturing global information from the input data. First, an in-depth analysis assessment of the various transformer-based semantic segmentation architectures, including UperNet with vision transformer and Swin transformer, SegFormer, Mask2Former, and UniFormer, was conducted. Second, the integration of spectral data on the performance of ViTs was evaluated. Moreover, the models’ generalizability and complexity effect on the segmentation effectiveness were assessed. Accordingly, a postprocessing strategy was developed to aid in delineating and counting date palm trees from semantic segmentation outputs. Results demonstrated that integration of WV-3 spectral data into the analysis resulted in a marked improvement in segmentation quality. The UniFormer, UperNet-Swin, and Mask2Former models demonstrated considerable improvements in multispectral data analysis, with increases in mean intersection over union (mIoU) of 2.17% (77.88% mIoU, 86.01% mean F-score [mF-score]), 2% (78.10% mIoU, 86.18% mF-score), and 1.15% (77.36% mIoU, 85.59% mF-score), respectively, compared with their RGB-based results. Evaluations of model transferability also indicated that Mask2Former, UniFormer, and UperNet-Swin transformers efficiently adapted to multispectral data in the Dibba region. These models achieved mIoU scores of 84.36%, 84.25%, and 83.17% and mF-scores of 90.95%, 90.87%, and 90.13%, highlighting their effectiveness and potential for broader regional application. This research highlights the efficacy and feasibility of using ViTs with WV-3 multispectral data for accurate and comprehensive surveying of date palm plantations, enabling the development of palm tree inventories and continuously updating geospatial databases.
Chaos in analog electronic circuits: comprehensive review, solved problems, open topics and small example
(MDPI, 2022-11-04) Petržela, Jiří
This paper strives to achieve a comprehensive review of chaos in analog circuits and lumped electronic networks. Readers will be guided from the beginning of the investigations of simple electronic circuits to the current trends in the research into chaos. The author tries to provide the key references related to this issue, including papers describing modern numerical algorithms capable of localizing chaotic and hyperchaotic motion in complex mathematical models, interesting full on-chip implementations of chaotic systems, possible practical applications of entropic signals, fractional-order chaotic systems and chaotic oscillators with mem-elements.
Voltage Gain-Controlled Third-Generation Current Conveyor and its All-Pass Filter Verification
(IEEE, 2017-09-04) Herencsár, Norbert; Kartci, Aslihan; Koton, Jaroslav; Tsirimokou, Georgia; Psychalinos, Costas
The paper presents a new active building block (ABB) called minus-type voltage gain-controlled third-generation current conveyor (VGC-CCIII) in which the voltage gain between Y to X terminal can be controlled. The usefulness of the tunable feature in the presented ABB is demonstrated in current-mode {0.3rd; 0.5th; 0.7th; 1st}-order all-pass filter (APF) employing single VGC-CCIII, one capacitor, and one resistor. The theoretical results of the integer- and fractional-order APF are verified by SPICE simulations based on readily available IC OPA860 macromodel, which can also be used in experiments.
Electronically Tunable Oscillator Utilizing Reinforced Controllable Parameters
(IEEE, 2019-10-31) Langhammer, Lukáš; Šotner, Roman; Domanský, Ondřej
This paper presents a novel solution of an oscillator with electronically adjustable oscillation condition (CO) and frequency of oscillations (FO). Oscillation condition is controlled by current gain and frequency of oscillations is adjustable by transconductance and intrinsic resistance of used active elements. Both CO and FO are mutually independent. Moreover, special feature of CO allows boosting parameter driving FO (transconductance) and then shifting the whole FO range to higher bands. It allows to keep values of passive elements (capacitors especially) in satisfactory range even for higher value of FO. Simulations in PSpice confirms this hypothesis.

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