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Povzetek: Satellite observations of sea surface temperature (SST) are essential for accurate weather forecasting and climate modeling. However, these data often suffer from incomplete coverage due to cloud obstruction and limited satellite swath width, which requires development of dense reconstruction algorithms. The current state of the art struggles to accurately recover high-frequency variability, particularly in SST gradients in ocean fronts, eddies, and filaments, which are crucial for downstream processing and predictive tasks. To address this challenge, we propose a novel two-stage method CRITER (Coarse Reconstruction with ITerative Refinement Network), which consists of two stages. First, it reconstructs low-frequency SST components utilizing a Vision Transformer-based model, leveraging global spatio-temporal correlations in the available observations. Second, a UNet type of network iteratively refines the estimate by recovering high-frequency details. Extensive analysis on datasets from the Mediterranean, Adriatic, and Atlantic seas demonstrates CRITER's superior performance over the current state of the art. Specifically, CRITER achieves up to 44 % lower reconstruction errors of the missing values and over 80 % lower reconstruction errors of the observed values compared to the state of the art.
Ključne besede: deep learning, reconstruction algorithms, satellite measurements
Objavljeno v DiRROS: 14.10.2025; Ogledov: 237; Prenosov: 106
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Povzetek: The investigation focused on the quasicrystalline aluminum alloy Al-Mn-Cu-Mg-Si-Ti. The influence of microstructure of aluminum alloy strengthened with quasicrystals on its corrosion resistance was studied. The properties of newly designed quasicrystalline aluminum alloy (QC) were compared to the properties of standard AlSi9Cu3 alloy (DIN 226). Both aluminum alloys (QC and AlSi9Cu3) were cast in a steel die with a controlled cooling rate. After the preparation of the samples, the microstructural characterization was carried out. In the quasicrystalline alloy, the microstructure was dominated by a primary phase with fivefold symmetry, representing the quasicrystalline phase. To investigate corrosion properties, open-circuit potential, linear polarization and potentiodynamic polarization measurements were performed. The influence of corrosion on mechanical properties was studied by conducting tensile tests on environmentally exposed alloys. It was concluded that the quasicrystalline alloy has comparable corrosion properties to the commercially widely used AlSi9Cu3 alloy. In the latter alloy, corrosion was observed to initiate in the vicinity of the Al2Cu intermetallic compound particles. In the case of the QC alloy, corrosion attacked mainly the αAl phase (matrix).
Ključne besede: quasicrystals, corrosion, aluminum alloys, microstructure, electrochemical measurements
Objavljeno v DiRROS: 14.07.2025; Ogledov: 481; Prenosov: 402
Celotno besedilo (2,96 MB)
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Povzetek: In this work, operando sulfur X-ray emission measurementson a Li−S battery cathode were performed using a laboratory setup as analternative to more common synchrotron radiation based absorptionstudies. Photoexcitation by an X-ray tube was used. Valence-to-core Kβ X-ray emission spectra were recorded with a wavelength dispersive crystalspectrometer in von Hamos geometry, providing excellent energyresolution and good detection efficiency. The setup was used to recordex situ S Kβ emission spectra from S cathodes from the Li−S battery andalso under operando conditions. Average S oxidation state within thebattery cathode during battery cycling was determined from the shape ofthe Kβ emission spectra. A more detailed S species characterization wasperformed by fitting a linear combination of previously measuredlaboratory synthesized standards to the measured spectra. Relative amounts of different S species in the cathode were determinedduring the cycling of the Li−S battery. The main advantage of X-ray emission spectroscopy is that it can be performed onconcentrated samples with S loading comparable to a real battery. The approach shows great promise for routine laboratory analysisof electrochemical processes in Li−S batteries and other sulfur-based systems under operando conditions.
Ključne besede: X-ray emission spectroscopy, lithium−sulfur batteries, operando measurements, oxidation state, von Hamos spectrometer
Objavljeno v DiRROS: 19.12.2024; Ogledov: 998; Prenosov: 428
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Povzetek: This paper presents results of in-plane shear tests carried out at the ZAG laboratory in Ljubljana (Slovenia) on a RC frame with masonry infill made of clay blocks (KEBE OrthoBlock). The frame was loaded with constant vertical loads at the top of the columns and then by gradually increasing horizontal cyclic loads at the top beam level. Acquired forces and measured displacements allowed capturing hysteretic behavior for determination of dissipation energy. In addition, two Digital Image Correlation (DIC) systems, Aramis and the CivEng Vision, were used to visualize the behavior of the tested specimens, with an emphasis on computing locally required information about the behavior of highly deformable interfaces. Three types of specimens were tested in-plane: the reference specimen in form of plain RC frame, the reference specimen with constructed masonry infill without any strengthening and the specimen, previously damaged and then strengthened on both sides using glass mesh bonded to the infill and the RC frame using flexible adhesive made of polyurethane matrix (Glass Fiber Reinforced PolyUrethane - GFRPU system). The strengthening process, allowed the specimen to withstand additional cyclic loads, reaching a maximum drift of 3.6 % without serious damage disqualifying the structure from further exploitation. The GFRPU strengthening system was found to be highly effective in preventing infill collapse of damaged masonry infill wall during in-plane loading. Additionally, the results of extended thermal analysis of PU are presented as polymers are, in general, a material, poorly resistant to heat. However, the analyzed PU manifested stable properties up to 200 degrees Celsius, which makes this material promising in civil engineering applications at elevated temperatures.
Ključne besede: masonry blocks, damaged infill, fiber Reinforced PolyUrethane, external composite strengthening, in-plane shear, thermal tests, DIC measurements
Objavljeno v DiRROS: 14.08.2024; Ogledov: 936; Prenosov: 587
Celotno besedilo (21,68 MB)
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Povzetek: Paper presents selected results of the diagnostic load testing of a newly-built footbridge in Novo Mesto, Slovenia. The bridge is significant as the first bridge in Slovenia being built with the stress ribbon technology. The diagnostic load testing took place in March 2023 and comprised of three-stage static load testing, dynamic testing with a light truck driving over artificial obstacles, and measurement of ambient vibrations. The consistency between the actual response of the bridge and the response of the finite element (FE) model, used in the design, was evaluated by comparing vertical displacements from the static load testing, natural frequencies and mode shapes. The comparison of the results indicates a satisfactory agreement between the measurements and the response of the FE model, confirming the appropriateness of the employed FE model.
Ključne besede: bridge, bridge response measurements, stress ribon, load test
Objavljeno v DiRROS: 14.08.2024; Ogledov: 883; Prenosov: 583
Celotno besedilo (16,88 MB)
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