20883 research outputs found
Sort by
Size effect on bending strength and failure modes of finger-jointed timber
No full textFinger-jointed timber boards for cross-laminated timber production are typically assigned the same characteristic bending strength (fm,j,k) if produced from the same strength class, regardless of differences in their cross-sectional dimensions. To validate the relevance of this approach, this study investigated the effects of cross-sectional dimensions on the bending performance of finger-jointed timber produced from spruce (strength class: C24). A large industrial dataset of 1100 specimens, with seven thicknesses (ranging 20 to 40 mm) and variable widths, were statistically analyzed. The bending tests were performed with a constant span-to-depth ratio (l/h = 18), meaning thinner specimens had a shorter test span. Bending strength was modeled with Bayesian multilevel linear model, and the proportions of three quality-control failure modes (joint interface failure, joint base failure, and outside-joint failure) were analyzed with a zero-one-inflated Dirichlet regression. Based on the results, all groups with n ≥ 100 exceeded the declared fm,j,k of 27.6 MPa, with characteristic strengths of 43.7 MPa (+58.3 %), 40.0 MPa (+45.0 %), and 38.3 MPa (+38.8 %) for the 20-, 30-, and 40-mm thickness groups, respectively. Thinner specimens demonstrated higher bending strength with convincing evidence (pairwise contrasts PD = 100 % with 95 % HDPIs entirely below zero), while width had no credible effect (PD < 95 %). Dirichlet regression revealed shifts in failure mode proportions with varying strength. Higher bending strengths were associated with a higher proportion of joint interface failure. Outside‑joint failure was observed with a higher proportion in lower-strength and thicker specimens. Overall, assigning uniform fm,j,k to various cross-sectional dimensions proved to give adequate safety margins. Beyond the uniform fm,j,k, however, statistical evidence of a size effect on both bending strength and failure modes was observed. The magnitude of the observed size effect reflects the combined influence of increasing thickness and test span under the current quality control bending test regime, which means a coupled change in stressed volume and geometry rather than a pure cross-section scaling effect. These findings are relevant to flatwise four-point bending tests on finger-jointed boards from industrial production made with visually graded C24 spruce with thickness ranging 20 to 40 mm
Prikaz nekaterih teoretskih dognanj o vedenjskih in čustvenih težavah ter motnjah otrok in mladostnikov
No full text
Attitudes of Slovenian and Italian preschool teachers on the inclusion of children with visual impairments in STEAM activities
No full textPolyphenolic composition, genetic profile and in vitro antioxidant and cytotoxic activities of artichoke varieties “Strunjanska articoka”, “Romanesco” and "Violetto di Romagna"
No full textIn recent years, artichokes have gained attention as functional foods due to their polyphenol content and health benefits. While Italian varieties have been widely studied, the Slovenian landrace “Strunjanska articoka” remains largely unexplored. This study compared “Strunjanska articoka” with two Italian varieties, “Romanesco” and “Violetto di Romagna”, assessing genetic profiles, chemical composition, antioxidant activity, and effects on lipid accumulation. The genetic analysis confirmed the uniqueness and clear differentiation of the landrace “Strunjanska articoka” from the two commercial varieties. Analysing the profiles of phenolic compounds in the leaf extracts of these morphologically different artichoke varieties underlines their unique phytochemical composition, which translates into different health benefits. “Romanesco” showed the highest free radical scavenging activity (EC50 = 100 µg/mL), followed by “Strunjanska articoka” (EC50 = 143 µg/mL), and “Violetto di Romagna” (EC50 = 160 µg/mL). Importantly, “Strunjanska articoka” demonstrated superior cytoprotective effects against oxidative stress in HepG2 and CCD112CoN cells. It also reduced lipid accumulation in HepG2 cells, along with “Violetto di Romagna,” whereas “Romanesco” did not. These findings justify further investigation into the potential therapeutic effects of “Strunjanska articoka” and support the rationale for its cultivation.https://repozitorij.upr.si/admin/GradivoDatoteke.php?id=2218
Computing tree decompositions with small independence number
No full textThe independence number of a tree decomposition is the maximum of the independence numbers of the subgraphs induced by its bags. The tree-independence number of a graph is the minimum independence number of a tree decomposition of it. Several NP-hard graph problems, like maximum-weight independent set, can be solved in time n^O(k) if the input n-vertex graph is given together with a tree decomposition of independence number k. Yolov, in SODA 2018, gave an algorithm that, given an n-vertex graph G and an integer k, in time n^O(k^3) either constructs a tree decomposition of G whose independence number is O(k^3) or correctly reports that the tree-independence number of G is larger than k. In this article, we first give an algorithm for computing the tree-independence number with a better approximation ratio and running time and then prove that our algorithm is, in some sense, the best one can hope for. Our second result is that the exact computation of the tree-independence number is para-NP-hard: We show that for every constant k ≥ 4 it is NP-complete to decide whether a given graph has the tree-independence number at most k