1. Investigating transient seepage flow and heat transfer using optical fiber distributed temperature sensors and hydrothermal modelingYaser Ghafoori, Stanislav Lenart, Uroš Bohinc, Andrej Kryžanowski, 2025, original scientific article Abstract: Seepage during the first filling of a reservoir is a critical aspect for earth dams and embankments safety, which requires precise monitoring. The thermometric method has demonstrated significant potential for detecting seepage anomalies through continuous temperature measurements using optical fiber distributed temperature sensing (DTS). However, most previous research has primarily focused on thermal monitoring when seepage flow reached a steady-state condition, which highlights the need for more research on seepage and heat transfer in transient state, particularly in unsaturated soils during the reservoir’s first filling. This paper addresses the transient seepage flow and heat transfer during the first filling of a laboratory sand model. Temperature variations within the sand were recorded using an optical fiber DTS, while seepage progression was tracked through digital imaging at regular intervals, followed by image processing. A coupled hydrothermal numerical model was also developed to simulate transient seepage flow and heat transfer within the unsaturated and variably saturated sand. In numerical modeling, heat dispersion and the thermal conductivity of sand were investigated through parameter calibration. Results indicate that thermal monitoring using optical fiber DTS is an effective method for estimating the development of the phreatic line during the first filling of the reservoir. Numerical simulations further revealed that seepage velocity plays a key role in the heat transfer process during transient seepage. Additionally, the results highlight that heat dispersion significantly influences heat transfer, particularly during transient seepage flow, whereas the effect of thermal conductivity is relatively minor as seepage progresses.
Keywords: seepage, phreatic line, temperature, heat dispersion, optical fiber DTS
Published in DiRROS: 09.05.2025; Views: 73; Downloads: 30
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2. The effect of curing temperature and thickness of polybutyl methacrylate siloxane coatings on the corrosion protection of structural steel S355Damir Hamulić, Gregor Medoš, Dorota Korte, Peter Rodič, Ingrid Milošev, 2023, original scientific article Keywords: structural steel, siloxane polybutyl methacrylate sol-gel, curing temperature, thickness, porosity
Published in DiRROS: 23.04.2025; Views: 150; Downloads: 51
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4. Comparison of some epigean and troglobiotic animals regarding their metabolism intensity. Examination of a classical assertionTatjana Simčič, Boris Sket, 2019, original scientific article Abstract: This study determines oxygen consumption (R), electron transport system (ETS) activity and R/ETS ratio in two pairs of epigean and hypogean crustacean species or subspecies. To date, metabolic characteristics among the phylogenetic distant epigean and hypogean species (i.e., species of different genera) or the epigean and hypogean populations of the same species have been studied due to little opportunity to compare closely related epigean and hypogean species. To fill this gap, we studied the epigean Niphargus zagrebensis and its troglobiotic relative Niphargus stygius, and the epigean subspecies Asellus aquaticus carniolicus in comparison to the troglobiotic subspecies Asellus aquaticus cavernicolus. We tested the previous findings of different metabolic rates obtained on less-appropriate pairs of species and provide additional information on thermal characteristics of metabolic enzymes in both species or subspecies types. Measurements were done at four temperatures. The values of studied traits, i.e., oxygen consumption, ETS activity, and ratio R/ETS, did not differ significantly between species or subspecies of the same genus from epigean and hypogean habitats, but they responded differently to temperature changes. Higher Q10-values for oxygen consumption of N. stygius than N. zagrebensis in the temperature range 10-20°C and higher Ea indicated higher thermal sensitivity in the subterranean species. On the other hand, lower Q10 and Ea-values for ETS activity of N. stygius than N. zagrebensis indicated more thermally stable enzymatic machinery in N. stygius than N. zagrebensis. In Asellus, we observed a similar trend of lower Ea for oxygen consumption and higher Ea for ETS activity in epigean than the troglomorphic subspecies, but the values did not differ significantly between the two. Our most important conclusion is that the low metabolic rate is not a universal property of troglobiotic animals, and the degree of metabolic adaptation is not necessarily in agreement with the degree of morphological adaptation (troglomorphy).
Keywords: food scarcity, temperature, oxygen consumption, ETS activity, amphipod, isopod
Published in DiRROS: 12.03.2025; Views: 145; Downloads: 135
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5. Simulation of high-temperature corrosion behavior of Ti6Al4V alloy in marine environmentsRongtao Zhu, Liang Zhang, Yuan Bo, Wei Chen, Shilu Chen, Shan Chi, Chunjiang Guo, Zhiwen Xie, 2025, original scientific article Keywords: Ti6Al4V alloy, high-temperature oxidation, hot-salt test, marine environment
Published in DiRROS: 21.02.2025; Views: 265; Downloads: 146
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7. Simulation of temperature field in steel billets during reheating in pusher-type furnace by meshless methodQingguo Liu, Umut Hanoglu, Zlatko Rek, Božidar Šarler, 2024, original scientific article Abstract: Using a meshless method, a simulation of steel billets in a pusher-type reheating furnace is carried out for the first time. The simulation represents an affordable way to replace the measurements. The heat transfer from the billets with convection and radiation is considered. Inside each of the billets, the heat diffusion equation is solved on a two-dimensional central slice of the billet. The diffusion equation is solved in a strong form by the Local Radial Basis Function Collocation Method (LRBFCM) with explicit time-stepping. The ray tracing procedure solves the radiation, where the view factors are computed with the Monte Carlo method. The changing number of billets in the furnace at the start and the end of the loading and unloading of the furnace is considered. A sensitivity study on billets' temperature evolution is performed as a function of a different number of rays used in the Monte Carlo method, different stopping times of the billets in the furnace, and different spacing between the billets. The temperature field simulation is also essential for automatically optimizing the furnace’s productivity, energy consumption, and the billet’s quality. For the first time, the LRBFCM is successfully demonstrated for solving such a complex industrial problem.
Keywords: pusher-type reheating furnace, steel, temperature field, radiation, convection, diffusion, strong form meshless method, radial basis functions
Published in DiRROS: 20.12.2024; Views: 294; Downloads: 153
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8. Phloem : a missing link in understanding tree growth response in a changing environmentJožica Gričar, 2024, original scientific article Abstract: Although the activities of various tree organs and tissues are under different environmental and internal constraints, they need to be coordinated to ensure whole-tree functioning. Dusart et al. (2024) conducted a heating experiment on branches of Juglans regia saplings during the entire growing season to examine the effect of temperature on primary (bud) and secondary (xylem) growth. They found that primary and secondary meristems responded asynchronously to elevated temperature, which suggests that lack of coordination mechanisms between primary and secondary growth at crown scale could have a potential impact on canopy and tree architecture.
Keywords: phloem, wood anatomy, tree growth, angiosperms, bark, meristem, non-structural carbohydrates, primary growth, radial growth, secondary growth, temperature, xylem
Published in DiRROS: 05.12.2024; Views: 236; Downloads: 160
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10. In pursuit of change : divergent temporal shifts in climate sensitivity of Norway spruce along an elevational and continentality gradient in the CarpathiansAndrei Popa, Jernej Jevšenak, Ionel Popa, Ovidiu Badea, Allan Buras, 2024, original scientific article Abstract: Across much of Europe, climate change has caused a major dieback of Norway spruce (Picea abies L.), an economically important tree species. However, the southeasternmost fringe of this tree species – the Eastern Carpathians – has not yet suffered large-scale dieback. Studying temporal shifts of climate sensitivity (TSCS) over time may elucidate the degree to which Norway spruce may be vulnerable to climate-change induced decline in upcoming decades. Under this framework, we analyzed a regional tree-ring network comprising >3000 trees, with the aim of quantifying TSCS since 1950. We mathematically defined TSCS as the slope parameter of the regression of climate sensitivity (the correlation coefficient) over time. Given the often-observed contrasting shift of climate sensitivity at low versus high elevations, we were particularly interested in studying potentially divergent TSCS along elevational and spatial gradients. Our analyses revealed several indications of TSCS for Norway spruce in the Eastern Carpathians. First, at high elevations (>1100 m a.s.l.), we found that the positive link between summer temperature and spruce growth decreased significantly over the study period. In turn, these trees, over time, featured an increasing positive relationship with late winter temperatures. At low elevations (<800 m a.s.l.), the signal of positive summer Standardised Precipitation-Evapotranspiration Index (SPEI) correlation became more frequent among sites towards 2021, while the strength of the positive winter SPEI correlation from the previous growing season weakened. Our results revealed that TSCS was driven significantly by an elevational climate gradient and a longitudinal continentality gradient. Overall, our findings indicate that Norway spruce is increasingly affected by water limitations under climate change at low elevations, highlighting a potentially rising risk of decline of this species in the Eastern Carpathians.
Keywords: temperature, water availability, climate change, tree-ring width, non-stationarity, Picea abies, daily climate-growth relationships
Published in DiRROS: 30.09.2024; Views: 473; Downloads: 750
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