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Corrosion behaviour of AISI 348 stainless steel in simulated WWER environment and during LOCA conditions
Full text linkThis study investigates the corrosion and high-temperature oxidation behaviour of AISI 348 stainless steel under normal and extreme conditions for potential nuclear applications.Plate specimens were exposed to simulated WWER primary water conditions in an autoclave at 360 °C for extended duration, reaching up to 1659 days. In addition to long-term exposure testing, short-term high-temperature oxidation experiments were performed at temperatures up to 1 400 °C to evaluate oxide scale formation, spallation behaviour, and structural integrity. Characterization techniques included Mössbauer spectroscopy for oxide phase identification, microhardness measurements, and optical microscopy for grain size evaluation. Mechanical testing, including ductility assessment and microhardness measurements, was conducted after high-temperature exposure to evaluate the material’s ability to retain mechanical integrity under accidental conditions
Application of the Optimized Regression to Volume Expansion Evaluation of Cement Paste with Fly Ash and MgO Expansive Additive
Full text linkFew studies have been conducted on the use of machine learning (ML) techniques to predict the volume expansion (Ve) of cement paste when fly ash (FA) and MgO expansive addition (MEA) are present. Utilizing a set of data that contained 170 experimental results that were obtained from previous research, the purpose of this study was to develop and evaluate ML algorithms for the assessment of Ve. To achieve this, the Extra tree regression (ETR) was created. The technique uses FA, Portland cement (PC), MEA, and sample age (Age) as input parameters. The Red-Tailed Hawk Algorithm (RTHA) and the Electric Eel Foraging Algorithm (EEFA) establish the hyperparameters of ETR, which greatly affect its effectiveness. The variation percentages of the two models developed for these measures are a minimum of 13%; in some cases, this variation decreases by 53%, illustrating the ETR (R)\u27s predictive reliability and efficacy. For instance, for the RMSE index, ETR (R) achieved values of 0.0053 and 0.01 during the training and testing phases, which are about 28% and 14% lower than the corresponding values of ETR (E) at 0.0068 and 0.0114, correspondingly. The ETR (R) model is somewhat superior to the alternative model regarding its purpose.
Received: 21.10.2025
Received in revised form: 13.2.2025
Accepted: 1.9.202
Experimental and statistical analysis of soil stabilization to avoid landfilling
Full text linkClayey soil is a moisture-sensitive material whose properties pose geo-environmental challenges in the construction sector. Soil stabilization through lime treatment offers advantages using local unsuitable soils without landfilling. This study investigates lime treatment and stabilization of sensitive reddish clay soil from the Setif region, Algeria. Geotechnical, chemical, and physic-chemical characterizations of the clayey soil with different percentages of dry lime (i.e., 0% to 9% by weight with intervals of 3%) were conducted. The standard plasticity test shows that the lime treatment causes a decrease in the plasticity index (from 30.7 to 22.1%) and methylene blue value (from 5% to 2.71%). Furthermore, the compressive strength test revealed a 16-fold increase in unconfined compressive strength (UCS) after 28 days with 6% lime (130 kPa vs 2100 kPa). However, a decrease in dry density was also observed (16 kN/m3 vs 15.7 kN/m3). Chemical and physic-chemical analyses using X-ray fluorescence and diffraction revealed the appearance of other chemical elements and mineral phases. Finally, ANalysis Of VAriance (ANOVA) was used to evaluate the effect of curing time and lime content on UCS. Both variables affected the strength development positively. The lime content, on the other hand, was two times more efficient than the curing time
Testing of available measurement methods for cubature calculations
Full text linkTato studie zkoumá nákladově efektivní techniky zaměřování pro efektivní sběr dat, zejména se zaměřením na měření objemu nebo kontrolu kubatury. Termín "kubatura" označuje objem hmoty. Česká inspekce životního prostředí testovala metody včetně přístrojů GNSS, UAV a videogrammetrie, aby našla technologii, která zjednoduší inspekce skládek. Tento článek porovnává data z fotogrammetrie, videogrammetrie a zpracovaných mračna bodů, vypočítává objemy pomocí softwaru 3Dsurvey. Cílem je vyhodnotit tyto metody na základě jejich efektivity, nákladů a technologických požadavků.This study examines cost-effective surveying techniques for efficient data collection, especially focusing on volume measurement, or cubature control. The term "cubage" refers to the volume of a mass. The Czech Environmental Inspectorate tested methods including GNSS instrumentation, UAVs, and videogrammetry to find a technology that simplifies landfill inspections. This paper compares data from photogrammetry, videogrammetry, and processed point clouds, calculating volumes using 3Dsurvey software. The goal is to evaluate these methods based on their efficiency, cost, and technological requirements
Preliminary design of optical emission spectroscopic diagnostics for Thailand Tokamak 1 (TT-1)
Full text linkThailand Tokamak 1 (TT-1), which employs a circular poloidal cross-section, has been operated with a set of poloidal limiters since its installation was completed in June 2023. This device currently lacks essential plasma diagnostics and auxiliary heating systems. At present, light emission is observed only by a visible camera. Although intense line emission has been detected, it remains poorly characterized. To support further research on impurity transport in TT-1, even in Ohmic mode, spectroscopic diagnostics are necessary. This study reports on the development progress of optical emission spectroscopic (OES) diagnostics, including the preliminary design, fabrication, and optical calculations
Spectroscopy of plasma of electric arc discharge between Cu-Mo composite electrodes
Full text linkThis work is devoted to the study of thermal plasma of electric arc discharges between composite Cu-Mo electrodes by optical diagnostic techniques. The electrodes were fabricated from copper–molybdenum composite materials. The arc discharge was ignited in an argon flow at a direct current of 3.5 A and a discharge gap of 8 mm. The absolute intensities of the spectral lines emitted by the plasma were registered in the spectral range of 430–650 nm. Radial distributions of key plasma parameters, namely excitation temperature and number densities of metals, were determined. For this purpose, the Boltzmann plot technique was applied using selected spectral lines of Cu I and Mo I. Particular attention was paid to the applicability of the local thermodynamic equilibrium assumption in the arc plasma under such discharge conditions
Rapid prediction of insulating gas performance: Leveraging XTB calculations for high-throughput screening of SF₆ alternatives
Full text linkAddressing the environmental challenge posed by sulfur hexafluoride (SF6) due to its extremely high Global Warming Potential (GWP), the development of eco-friendly alternative gases is imperative. Efficient prediction of key gas properties is crucial for virtual screening and generative model optimization, but traditional quantum chemical calculations for molecular descriptors are time-consuming for high-throughput screening. This study proposes and validates a rapid modeling framework using XTB semi-empirical quantum chemical calculations to efficiently compute physicochemical parameters, which provide the basis for core gas properties such as dielectric strength, boiling point, and GWP. Testing confirms the XTB method offers both high speed and acceptable accuracy, which establishes a foundation for virtual screening, accelerating the discovery of environmentally benign insulating gases
Concept for evaluating the safety of a dynamically loaded gearbox reducer
Full text linkThe safety of dynamically loaded gearbox reducers is of interest to companies and the scientific community, and any research and conclusion in this direction is a significant contribution, as this problem has not been widely discussed in scientific articles. This article presents a concept for evaluating the safety of a dynamically loaded reducer, specifically built into a rotating excavator used in surface coal mines for its working wheel. The presented concept offers three ways to evaluate safety: according to factors of safety, according to operating parameters, and according to load capacity and loads. A methodology was presented for all three ways, which was applied to a specific reducer under specific working conditions, and output results were obtained. The output results were analysed and conclusions were drawn using the specific reducer. However, it was established, based on the author’s experience, that these results can be generalised for similar reducers operating under the same or similar working conditions. The set concept can be applied to the safety assessment of other dynamically loaded gear reducers
High-resolution mapping of secondary cosmic rays with miniaturised stacked pixel telescope
Full text linkWe performed detailed measurements of the secondary cosmic ray field in the lower atmosphere (at 200 m). We use a miniaturised particle telescope consisting of two closely stacked synchronised Timepix3 detectors. Position-, spectral-, and time-sensitive particle tracking provides enhanced particle-type resolving power and high angular resolution mapping of charged particles. Evaluation and calibration of the telescope synchronised tracking and directional response was performed with proton and electron beams. The telescope architecture, modeled angular response and developed data analysis provide accurate composition characterisation and high-angular resolution directional mapping of the charged particle component. In particular, the muon component can be resolved to a high degree over the photon and electron components in the lower atmosphere. The muon angular flux is measured in a wide field of view with enhanced discrimination
ADVANCED PHASE ANALYSIS OF RETINAL VIDEOS USING ECG
Full text linkSpectral analysis is one way to further investigate retinal hemodynamics and vessel pulsation. Specifically, for the phase component of the spectrum of retinal videos, the significance in retinal analysis has not yet been fully defined. The aim of this study is to determine whether the value of phase is relevant in the classification of blood vessels (arteries and veins). Using electrocardiographic signals recorded simultaneously with retinal video, we can determine how the phase component of the video behaves with respect to the cardiac cycle. As part of the experiment, we measured the retinal video of the left eye of 13 healthy subjects. We found that the phase delay between the maximal pulsation of arteries and veins in the optic nerve head tissue is on average 9% of the actual cardiac period. For our data set, this corresponds to an average time delay of 80.22 ms. We conclude that this phase delay between pulsations of arteries and veins can help in the classification of vessels in the optic nerve head