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Abstract: Water and ice accumulation on surfaces present significant challenges in numerous fields, causing issues such as corrosion of metallic surfaces and a broad range of problems associated with increased weight, altered hydro-/aerodynamics, vibrations, and heat transfer resistance. Currently, passive solutions, such as functionalized surfaces that also offer improved anti-corrosive properties, are being focused on. This study presents the fabrication and evaluation of four functionalized superhydrophobic surfaces on 1050A aluminum alloy samples using nanosecond laser texturing and self-assembled monolayer grafting to enhance anti-icing and corrosion protection. The developed surfaces exhibited superhydrophobicity with static and dynamic contact angles above 163° and a contact angle hysteresis below 2°, maintaining their nonwetting properties after multiple icing/deicing cycles. Three surfaces significantly lowered ice nucleation temperature with the lowest average value of -20.1 °C recorded on the surface with shallow, non-distinct features. The freezing delay was prolonged up to 468 % and 944 % at -15 °C and -20 °C, respectively, in comparison with the untreated reference surface. The superior anti-icing properties of the two surfaces with shallow structures, fabricated using a lower laser pulse fluence than those with deep structures, are ascribed to a lower number of potential active nucleation sites for condensation of water vapor and freezing initiation. In comparison with an untreated surface, ice adhesion was reduced by up to 60 % on surfaces with shallow features but increased between 33 % and 84 % on surfaces with deep morphological features. Repeatable cascade freezing was observed on one of the surfaces, which also exhibited the poorest anti-icing performance. Surfaces with non-distinct or irregular channels exhibited better corrosion properties than surfaces featuring well-defined laser-etched channels. The surface with the lowest surface roughness exhibited the best properties in all evaluations, providing a good starting point for future optimization with a focus on surfaces with micron scale and submicron features instead of the more traditional surfaces with structures on the scale of tens of microns. Overall, this functionalization approach is promising for industrial use, simultaneously offering enhanced robustness, anti-icing behavior, and corrosion protection.
Published in DiRROS: 01.07.2025; Views: 471; Downloads: 274
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Keywords: varstvo gozdov, morfološke analize
Published in DiRROS: 01.07.2025; Views: 349; Downloads: 0
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Abstract: Dinamika poslovanja v gradbeništvu je v zadnjem desetletju dosegla lokalno dno v letu 2016, potem pa je pričela močno naraščati. Leti 2022 in 2023 sta bili po rasti izjemni leti, predvsem zaradi rasti del, financiranih iz kohezijskih sredstev in Načrta za okrevanje in odpornost. Leto 2024 je bilo spet nekoliko šibkejše, predvsem zaradi padca gradbenih del, kar je bilo povezano z zamudami pri izdaji gradbenih dovoljenj na upravnih enotah. Rast gradbenih del je sovpadala z rastjo števila gradbenih podjetij, katerih povprečna velikost, merjena s številom zaposlenih, je sčasoma vseeno nekoliko porasla. Dinamika črpanja kohezijskih sredstev je pomembno vplivala na dinamiko poslovanja v gradbeništvu. Gradbeništvo je predstavljalo okoli 6 % ustvarjene dodane vrednosti v slovenskem gospodarstvu, s čimer se je slovensko gradbeništvo uvrstilo na enajsto mesto med 27 EU državami. Prejemki zaposlenih so v zadnjem desetletju naraščali hitreje kot v povprečju in so bili v letu 2024 le še za desetino nižji od slovenskega povprečja. Kljub visoki rasti plač se je z izzivom pomanjkanja usposobljenih delavcev v zadnjih treh letih (2022-2024) soočala že polovica gradbenih podjetij. To zelo verjetno vpliva na nižjo produktivnost dela in na visoko rast plač oziroma stroškov dela na zaposlenega. Zaradi visokega deleža stroškov dela v dodani vrednosti gradbena podjetja ne morejo dodatno dvigovati plač, kar bi prispevalo k zmanjševanju primanjkljaja ponudbe delovne sile
Keywords: gradbena dela, dovoljenja, dodana vrednost, kazalnik zaupanja, omejitveni dejavniki
Published in DiRROS: 01.07.2025; Views: 313; Downloads: 152
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Abstract: Večnadstropne lesene stavbe so zaradi svoje lahkosti občutljive na nihanje zaradi vetra, kar lahko povzroča neugodje pri uporabnikih. Zato je merilo ugodja stanovalcev pogosto eden ključnih kriterijev pri projektiranju večnadstropnih lesenih stavb. V članku izračunamo pričakovane pospeške nihanja zaradi vetra za deset lesenih in hibridnih lesenih stavb z višinami med 22 m in 74 m, za katere so bili pridobljeni podatki o dimenzijah, masi ter dinamičnih lastnostih. Pospeški so bili izračunani po SIST EN 1991- 1-4:2005 ter ovrednoteni po ISO 10137. Parametrična analiza je pokazala, da lokacija stavbe najbolj vpliva na njen odziv, izmed dejavnikov oblike stavbe ima največji vpliv zaobljenost oziroma prirezanost robov. Ugotovljeno je bilo tudi, da je za doseganje merila ugodja pri nižjih stavbah primerneje povečati togost, pri višjih pa dodati maso. V analizo je bila vključena tudi trenutno najvišja lesena stavba na svetu, analiza pa je pokazala potencial gradnje še višjih lesenih stavb v prihodnosti.
Keywords: lesene stavbe, vetrna obtežba, nihanje stavbe, mejno stanje uporabnosti, parametrična analiza
Published in DiRROS: 01.07.2025; Views: 330; Downloads: 237
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Abstract: This study investigated gender-specific predictors of vault performance in gymnastics by applying machine learning techniques to analyse body composition and run-up dynamics. Data were collected from 27 national-level gymnasts (17 female, 10 male) during the Slovenian Cup competition. The focus on gender-specific predictors stems from fundamental physiological and biomechanical differences between male and female athletes, which influence force production, movement kinematics, and execution mechanics. A deeper understanding of these distinctions enhances the precision of performance modelling and supports the development of targeted, evidence-based training interventions. Spatiotemporal parameters of the run-up were recorded using the OptoGait system, while body composition was assessed with the Tanita DC-360. Principal Component Analysis (PCA) and Boosting regression models were used to identify key predictors of vault execution scores. These methods were selected for their ability to reduce dimensionality and capture complex, nonlinear relationships in performance data. The results revealed clear gender-specific patterns. For female gymnasts, the model explained 74.4% of the variance in execution scores, with Overall Lean Body Mass emerging as the most influential predictor (47.12% relative influence), followed by Overall Contact Phases (25.28%). For male gymnasts, the model demonstrated exceptionally high predictive power, explaining 97.8% of the variance, with Body Fat as the primary predictor (48.44% relative influence), followed by Flight and Contact Dynamics (35.22%). These findings suggest that training strategies should be tailored to gender-specific needs. For women, emphasis on lean muscle development, stride optimisation, and the coordination of rhythm and timing may be beneficial. For men, managing body fat levels, optimising flight and contact dynamics, and adopting an integrated approach to stride mechanics appear essential. Given the potential for misinterpretation of body composition metrics, a holistic approach to athletic conditioning is recommended. However, the study’s limitations, including the small sample size and cross-sectional design, warrant cautious interpretation. This research provides a foundation for future investigations into gender-specific factors affecting vault performance. Larger and longitudinal studies are needed to validate these findings and support the development of more precise training interventions.
Keywords: run-up characteristics, body composition, execution score, principal component analysis
Published in DiRROS: 01.07.2025; Views: 448; Downloads: 324
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