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Povzetek: A spatio-temporal video enhancement of a small-scale pool fire is performed to address the typically low spatial resolution and frame rate of inexpensive infrared (IR) cameras. Improving image quality can increase the applicability of low-cost thermal cameras for certain research tasks and analyses. The spatial resolution and frame rate are doubled, from 310 × 250 pixels (px) to 620 × 500 px, and from 25 frames per second (fps) to 50 fps, as well as from 50 fps to 100 fps. Spatial resolution enhancement is achieved using super-resolution methods based on deep learning, employing several pre-trained models: Fast Super-Resolution CNN (FSRCNN), Efficient Sub-Pixel Convolutional Network (ESPCN), Enhanced Deep Super-Resolution (EDSR), Laplacian Pyramid Super-Resolution Network (LapSRN), and Real-ESRGAN. The footage consists of an n-heptane pool fire recorded using a mid-wave infrared (MWIR) FLIR X6981 HS InSb camera. EDSR provides the best performance for both purely resized images and images subjected to complex degradation. For temporal enhancement, a pre-trained frame interpolation model, FLAVR (FlowAgnostic Video Representation), is used. The resulting interpolated frames appear realistic and preserve the overall flow direction and shape of the flame. The interpolated frames are compared with ground-truth data to validate the accuracy of the temporal enhancement.
Ključne besede: image processing, thermal camera, machine learning, pool fire
Objavljeno v DiRROS: 15.06.2026; Ogledov: 100; Prenosov: 70
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Povzetek: The fire performance of engineered timber structures is fundamentally controlled by the coupling between the in-depth temperature evolution of the timber elements and the internal compartment fire dynamics. Charring and heating of the timber during and after a fire are known to significantly degrade the mechanical capacity of timber elements, while also influencing the intensity and duration of burning by generating additional fuel and potentially inducing bond line failures. A series of large-scale fire experiments in cross-laminated timber (CLT) compartments with varying configurations of exposed timber surfaces and movable fuel loads has been performed to investigate these interrelationships, by measuring the charring, thermal penetration, and exposure conditions of the CLT elements. The extent of charring and in-depth heating was found to be primarily determined by the duration of heating—associated to the movable fuel load characteristics and occurrence of self-extinction or char fall-off. Significant in-depth temperature rise beyond the char front continued beyond the decay of the fire and cessation of charring. These findings highlight the importance of designing timber compartments to limit the duration of burning, and to account for the structural implications of thermal penetration during the cooling phase.
Ključne besede: compartment fires, heat transfer, thermal penetration, large-scale, mass timber, cross-laminated timber, charring, char fall-off, performance-based design
Objavljeno v DiRROS: 18.05.2026; Ogledov: 200; Prenosov: 55
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Povzetek: This study investigates the thermal behaviour of two opaque and one transparent thin intumescent coating at material level (coating only) and system level (coating applied at real scale on timber), and their effects on timber in fire. Micro-scale tests were conducted to examine the underlying mechanisms of intumescence and degradation for each coating individually, while bench-scale tests demonstrated how these behaviours translate to larger scales. Critical temperature and heat flux thresholds were identified at which the coatings begin to insulate the timber through the formation of the intumescent char layer, as well as those marking degradation of the layer and the reduction of its insulating efficacy. The findings highlight that coating type and thickness, heating conditions and exposure duration influence mass retention, swelling pattern, and the integrity of the intumescent char layer. Overall, the transparent coating exhibited lower durability than the opaque ones. It was also shown that, due to the similar temperature ranges of timber pyrolysis and coating swelling, timber degradation occurs close to the coated surface during the transient swelling process, resulting in a heated region of 15- 20 mm with negligible mechanical properties by the end of swelling. Therefore, intumescent coatings provide insulation progressively rather than immediately.
Ključne besede: mass timber, thin intumescent coatings, swelling, fire testing, charring, fire safety
Objavljeno v DiRROS: 08.04.2026; Ogledov: 173; Prenosov: 154
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Povzetek: With the rise of performance-based structural fire design, understanding the behaviour of materials during both the heating and cooling phases of a fire has become essential. Traditionally, research has focused on the heating phase, resulting in limited data on material properties during cooling, in particular for the free thermal strain of concrete. This gap is critical, as free thermal strain significantly influences load redistribution in reinforced concrete structures. Two experimental campaigns were conducted to expand the available data: one using the UGent HIFREP (‘High Intensity Fast-Response Electric Radiant Panel’) and the other employing an electric furnace. The first test campaign provided an extensive dataset on the residual thermal strain, whereas the time- consuming furnace tests provided data for the entire fire event (heating and cooling). These datasets were used to update an existing model through Bayesian inference, coherently integrating the new information. The outcome is a comprehensive probabilistic model that accurately captures the free thermal strain behaviour of concrete throughout both heating and cooling, allowing for a full reliability-based evaluation of concrete structures in fire.
Ključne besede: concrete, cooling, free thermal strain, fire safety, structural fire engineering, experiments, bayesian inference
Objavljeno v DiRROS: 10.03.2026; Ogledov: 329; Prenosov: 70
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Povzetek: In comparison to non-combustible construction materials commonly used for taller buildings, timber elements can significantly alter the fire dynamics in a compartment. This fundamentally challenges many of the conventional fire safety strategies and design approaches for mid-rise and high-rise buildings. Consequently, many building industry practitioners are questioning the limitations of existing methodologies, while searching for additional ways to account for this different fire behaviour in the design, construction, and operation of timber buildings. In seeking to address these questions, this chapter describes the state-of-the-art and recent advances in understanding the fire behaviour in compartments with areas of exposed timber (e.g., engineered wood products), and protected timber elements that may contribute to the fire if their encapsulation fails. Relevant experimental findings and engineering approaches to date are summarised and discussed, and design guidance is provided in relation to the typical phases of realistic or ‘natural’ fires, namely the growth phase, the fully-developed phase, the fire decay, and the cooling phase. Critical fire phenomena and their impacts on the fire safety strategy are addressed, such as fire spread; active fire suppression; heat induced delamination and char fall-off; and self-extinguishment.
Ključne besede: timber, fire dynamics, fire safety, self-extinguishment, heat induced delamination, char fall-off
Objavljeno v DiRROS: 18.11.2025; Ogledov: 568; Prenosov: 276
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