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Early steep optical decay linked to reverse shock for GRB200131A
Full text linkWe observed an optical afterglow of GRB200131A obtaining the first photometric point 63 s after the satellite trigger. This early observation shows a steep decay, suggesting either internal engine activity or a reverse shock. By fitting this data set, we show that the early data fit well as a reverse shock component of the GRB afterglow modeled as a thin shell expanding into a constant density interstellar matter. The fitting also shows a good agreement with a catalogued Milky Way galactic extinction and leaves little room for further extinction in the host galaxy. By judging several factors we conclude that the most likely redshift of this GRB is 0.9 ± 0.1
IMPROVED SYSTOLIC PEAK DETECTION IN PHOTOPLETHYSMOGRAPHY SIGNALS: FOCUS ON ATRIAL FIBRILLATION
Full text linkPhotoplethysmography (PPG) is a widely recognized non-invasive optical technique for monitoring blood volume changes. Recently, PPG signals have gained prominence in healthcare applications, including the detection of cardiac arrhythmias. Cardiac arrhythmias represent a significant global health challenge, with particular focus on identifying atrial fibrillation (AF), the most prevalent type. Accurate detection of systolic peaks in PPG signals is crucial for arrhythmia detection and other applications such as heart rate estimation and heart rate variability analysis. Despite the high accuracy of existing beat detection methods in healthy subjects, the performance in the presence of cardiac arrhythmias is lower. This study employs a deep learning method to enhance the detection of systolic peaks in PPG signals, even in the presence of AF. The model was trained on a dataset comprising 2,477 10-second PPG segments with over 37,000 annotated PPG peaks, including data from patients with AF. Our model achieved an F1 score of 97.3% on the test dataset and F1 score of 94.8% on the test dataset when considering only patients with AF
Mathematical modelling and analysis of three-dimensional Maxwell-Nanofluid flow over a bidirectional stretching surface in the presence of a magnetic field
Full text linkThe current study investigates the effects of thermal diffusion and diffusion thermoeffect on three-dimensional upper-convected Maxwell-Nanofluid flow across a bidirectional stretching surface in the presence of Brownian motion, thermophoresis, and thermal and mass Biot numbers. The current communication is also being carried out to consider the unique and innovative properties of nanofluids. The Rosseland approximation incorporates a nonlinear radiative heat flow in the energy equation. By adding applicable dimensionless variables and parameters, the governing equations are converted into a dimensionless form and then solved via finite element system. The paper delivers a comprehensive analysis of how various factors and other pertinent parameters influence the flow variables. These findings are presented visually through graphical representations, providing a clear and insightful understanding involved in this flow scenario. The results obtained demonstrate that it is an effective solution to the current problem. This new research has significant implications for the food industry, as well as for energy systems, biomedical engineering, and aeronautics. The numerical findings of this investigation are tangible and validated
Enhanced electric vehicle charging topology with integrated fuzzy-based shunt converter
Full text linkThis article presents a novel electric vehicle charging scheme that addresses power quality issues in distribution grids, caused by widespread EV charging. The system uses an interval type-II (IT-II) fuzzy-logic-based shunt converter, with a dual-direction converter enabling power flow from the grid to the EV (G2EV) and from the EV to the grid (EV2G). It incorporates iterative constant current (ICC) regulation for managing Li-ion battery charging and discharging. A fuzzy logic controller (FLC) based on an instantaneous reactive power model is used for the shunt converter, with an enhanced real-coded genetic algorithm (ERGA)-based type-I (IT-I) FLC control. The Performance is evaluated using THD analysis of the source current, and the system response is plotted. Simulations conducted in Matlab demonstrate improved power quality with harmonic distortion within acceptable limits, confirming the effectiveness of the proposed system in optimising EV charging while maintaining grid stability
Use of Contactless Spatial Data Collection Methods for Snow Cover Monitoring: Case Studies from Czech Mountains
Full text linkAccurate documentation of snow cover is critical for hydrological modeling, climate adaptation planning, and risk assessment in mountainous regions. This study presents a comprehensive methodology for snow cover monitoring using UAV-based LiDAR scanning, tailored to the specific environmental and technical constraints of Central European mountain ranges. Field campaigns were conducted across several Czech border mountain locations (Ore Mountains, Giant Mountains, Beskids Mountains), utilizing DJI Matrice 300 RTK equipped with Zenmuse L1 or L2 LiDAR sensors. Due to limitations in deploying traditional ground control points (GCPs) in remote and protected areas, the methodology emphasizes reliance on GNSS RTK corrections and minimal GCP use. The influence of two GNSS reference networks (CZEPOS and TopNet) was evaluated through photogrammetric analysis, revealing systematic elevation biases and spatial autocorrelation, with TopNet yielding slightly better results.
Various point cloud post-processing workflows were tested, including smoothing and noise filtering in DJI Terra, TerraSolid, and CloudCompare. The best visual and statistical results were obtained using a combined approach supplemented by a single foldable GCP. Ground point classification methods were assessed in both snow-free and snow-covered conditions. The most reliable method for snow-free filtering was the Spatix-based algorithm in TerraSolid, while snow-covered scenes required custom multi-criteria filtering in CloudCompare.
Validation was performed using over 4,500 RTK GNSS ground points and manual snow probe measurements. The methodology proved robust despite uncertainties from vegetation interference and manual measurement limits. This study delivers practical guidelines for operational snow cover documentation under constrained field conditions, and proposes improvements for future automation and validation.
Impact of Terrain and Environment on the Accuracy of Vehicle-Based Mobile Mapping Systems
Full text linkThe rapid collection of accurate spatial data and its use in various domains is driving the development of Mobile Mapping Systems (MMS). This study evaluates the accuracy of the Riegl VMX-2HA system in three different environments: an urban residential area, an open road section with an unobstructed view of the sky, and a forested roadway where GNSS signals are significantly affected. This research investigates the effect of these environments and different alignment methods on point cloud accuracy. A combination of GNSS, IMU and DMI was used to determine the trajectory, with measurements tied to GCPs. The study compares the results of the processing of the separate sections with the calculation of the entire section and evaluates the differences of the repeated measurements. The results show that aligning measurements without separating sections by environment improves accuracy. The results contribute to the optimisation of MMS-based data collection strategies and provide insight to improve the reliability of spatial data collection
Production of steel-concrete composite columns for blast tests
Full text linkThe resistance of structures to explosive impacts is a highly relevant issue in modern engineering. During an explosion, structures are subjected to extreme dynamic loads, which necessitate advanced materials and reinforcement strategies. UHPFRC, with its evenly distributed steel fibres, exhibits exceptional mechanical properties that make it well-suited for blast-resistant applications. Combining UHPFRC with steel reinforcement is expected to significantly mitigate structural damage under explosive loading.This article focuses on the process of production of testing steel-concrete column specimens under axial compressive load for evaluating their blast resistance. The initial section describes the test elements and the objectives of the experiment. The following section outlines the design and material properties of the concrete mixtures used. Subsequently, the production process, including formwork preparation and casting, is detailed. Finally, the results achieved from ongoing testing are briefly introduced
One-dimensional fluid modeling of methane dissociation in dielectric barrier discharge: Impact of voltage and dielectric constant
Full text linkThis paper presents a one-dimensional simulation of the dielectric barrier discharge (DBD) in pure methane under atmospheric pressure. By employing a fluid model integrated with a set of plasma chemistry to analyze discharge behavior, we study different plasma characteristics, including applied voltage, discharge current, electron and ion density, and diverse chemical species density. Additionally, the study investigates the influences of the variation of applied voltage and the insulation layer constant on the characteristics of the DBD reactor and methane conversion. The findings reveal that increasing the applied voltage and dielectric constant influences the discharge behavior, enhancing methane dissociation
How reliable are line intensities for temperature calculation using the Boltzmann plot method
Full text linkThis study investigates the reliability of electron temperature calculations for plasmas using line intensities, specifically through the Boltzmann plot method. Simulated spectra of a copper plasma reveal that while using line intensities may be sufficient under certain conditions, significant deviations arise under high-pressure and low-temperature scenarios. Our findings emphasize the need for caution, as inaccuracies can occur when the optical depth reaches a relevant magnitude
A review of numerical approaches on decaying arc plasmas in polyatomic C-F-O molecular gas flow with chemical non-equilibrium considerations
Full text linkThis study reviews two numerical models to simulate arc plasma decay in polyatomic molecular gas flows, focusing on chemically non-equilibrium (CNE) effects. The first model addresses C-F-O gas mixtures formed by CO2 with ablated PTFE vapor, incorporating 24 species and 98 reversible reactions with temperaturedependent rates. It predicts plasma composition and electron density during decay. The second model assumes irreversible C5F10O decomposition in CO2/O2 mixtures, validated by equilibrium analysis. Arc decay under free recovery is analyzed, highlighting the impact of reaction kinetics and gas composition on temperature and species evolution