Iskanje po repozitoriju

Opis: The construction sector’s substantial contribution to global energy consumption and CO2 emissions motivates the development of bio-based alternatives to fossil-derived rigid polyurethane (PUR) foam cores in structural sandwich panels. This study presents a comprehensive comparison of plywood sandwich panels manufactured with a rigid PUR foam containing a fast pyrolysis bio-oil (FPBO)-derived sugar polyol diluted with triethyl phosphate and panels of identical topology produced with a commercial reference PUR foam. In the bio-based formulation, a fraction of the sorbitol-based polyether polyol was replaced with the FPBO-derived sugar polyol. Both systems were characterized at the foam and panel levels for cellular microstructure, skeletal and envelope density, thermogravimetric stability, flammability, color, thermal conductivity and heat capacity, internal bond strength, compressive properties, and normal-incidence sound absorption and transmission loss. The newly developed foam exhibited similar skeletal density and porosity to the reference, comparable thermogravimetric stability with a slightly higher char residue, and lower thermal conductivity across the tested temperature range. Mechanical properties, including compressive strength, compressive modulus, and internal bond strength, showed minor reduction but remained within a comparable range. A distinct color change was observed, attributable to the presence of chromophoric constituents of the FPBO fraction. Overall, the results indicate that partial substitution of the fossil polyol with an FPBO-derived sugar polyol is technically feasible, yielding materials with comparable thermal, mechanical, or acoustic performance. No consistent performance advantage of either system was observed across the evaluated properties. The results support the potential of pyrolysis-derived bio-polyols for use in sustainable structural insulation products.
Ključne besede: bio-based polyol, fast pyrolysis bio-oil, rigid polyurethane foams, waste valorization
Objavljeno v RUP: 14.07.2026; Ogledov: 212; Prenosov: 6
Celotno besedilo (2,12 MB)
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Opis: Community detection reveals the functional organization of complex networks. Unlike edge-based methods, graphlet-based approaches use higher-order structures, but most studies focus on common motifs or lack validation on networks with known communities. We evaluate eight small motifs on synthetic and real-world networks and propose a framework that weights node pairs by their graphlet co-occurrence while preserving original edges. This captures both direct connections and local topology, improving community detection. Our results show that graphlet-based weighting consistently enhances performance, but no single motif is best for all networks. Simpler motifs can perform as well as dense cliques, suggesting that relying only on cliques may miss important connectivity patterns.
Ključne besede: community, network, graphlets, small-motif
Objavljeno v RUP: 01.07.2026; Ogledov: 234; Prenosov: 8
Celotno besedilo (6,14 MB)
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Opis: Environmental considerations have become increasingly important in the construction industry, driving the search for more sustainable alternatives to conventional building materials and solutions. One resource-intensive material used for structural decoupling is the impact-resilient layer, which, when installed in floating floors, is crucial for achieving the required insulation ratings. This study presents a methodology for developing an impact-resilient layer. The approach defines the key performance parameters of a floating floor and follows an experimental development approach based on prototyping. Prototypes are iteratively improved, with the first generation providing proof of concept and evolving into a final large-scale prototype that validates the impact insulation performance. To validate the approach, it is applied to the development of a wood-based resilient layer as a case study. The introduced resilient layer is highly sustainable and follows design for disassembly principles, while technically relying on a novel elastic response mechanism based on the flexural deformation of wooden strips. Over three generations of prototypes, the design evolved systematically, considering different geometric configurations, wood species, and wood-cork composites to manufacture the strips. The experimental evaluation focused on load-bearing capacity, dynamic stiffness, and damping ratio, also accounting for the inherent variabil ity of wood and wood moisture content as experimental parameters. A viable design was achieved and showed competitive impact sound insulation compared to established reference solutions. These results demonstrate that the proposed development approach can be successfully applied in practice and that a wood-based resilient layer can be a viable alternative to conventional market solutions.
Ključne besede: impact sound, sustainable insulation, floating floor, wood moisture content
Objavljeno v RUP: 23.06.2026; Ogledov: 341; Prenosov: 11
Celotno besedilo (3,98 MB)
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Opis: Near-infrared (NIR) spectroscopy combined with multivariate analysis was employed to investigate moisture- dependent hydrogen bonding of water in softwood cell walls. Spectral variations at equilibrium moisture con- tents were analyzed using principal component analysis and perturbation-correlation moving-window two- dimensional correlation spectroscopy to distinguish water populations with varying hydrogen-bond strengths. A distinct transition in hydrogen-bonding behavior was identified at approximately 10% wood moisture content. Below this threshold, water was found to predominantly engage in strong hydrogen bonds within wood cell walls. Above 10% moisture content, the relative contribution of strong hydrogen bonds to the overall wood- water hydrogen bond network decreased, whereas weakly hydrogen-bonded population became increasingly dominant. Experiments on modified wood and isolated polymers indicated that this transition originates mainly from wood polysaccharides, while lignin plays a minor role. These findings provide strong evidence for distinct water populations in wood cell walls, distinguished by their intermolecular hydrogen-bonding energies and predominant at specific wood moisture contents
Ključne besede: infrared spectroscopy, wood-water interactions, hydrogen bonding, wood cell wall, cellulose
Objavljeno v RUP: 05.06.2026; Ogledov: 368; Prenosov: 11
Celotno besedilo (4,60 MB)
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Opis: Disruptions in supply networks have caused many logistical and planning challenges in the last few years. The previous predictability of the shipping times of raw materials changed drastically due to various global issues, which affected many production areas, including the wood industry. This work is motivated by a case study of a Central European plywood production facility, where supply-side disruptions caused difficulties in meeting deadlines for downstream companies of the construction and furniture industry. As a result, the objective of production planners shifted towards mitigating the financial burden caused by cancellation penalties. Three MILP (Mixed-Integer Linear Programming) models and a genetic algorithm were developed to tackle the scheduling of a plywood production plant with raw material shipments and order deadlines. The novelty of the considered problem lies in the flexibility of swapping order deadlines from the same client, which was inspired by the real-life deals of the aforementioned company. The methods were tested on 120 benchmark instances of different sizes generated from real industrial data. The genetic algorithm terminated within 60 s for all instances and found the optimal or best-known solution in 71 of 80 short-horizon instances, while also remaining efficient on larger 30-day cases. As the solution approach is not specific to plywood production, it can be applied to scheduling problems in other fields as well, where similar disruptions can develop, and the production process features are covered by the Multi-Mode Resource-Constrained Project Scheduling Problem class.
Ključne besede: plywood, scheduling, MRCPSP, MILP, genetic algorithm
Objavljeno v RUP: 01.06.2026; Ogledov: 320; Prenosov: 8
Celotno besedilo (1,52 MB)
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