1. Overview of global long-distance road Transportation of industrial roundwoodKärhä Kalle, Milla Seuri, Patricio Miguel Mac Donagh, Mauricio Acuna, Christian Kanzian, Vladimir Petković, Robert Renato Cesar Gonçalves, Costa Luis Henrique Suppi, da Cruz Rodrigo Coelho, Tihomir Krumov, Matevž Triplat, 2024, pregledni znanstveni članek Povzetek: The aim of the study was to provide a comprehensive overview of global long-distance road transportation of industrial roundwood. The study focused on the maximum gross vehicle weight (GVW) limits allowed with different timber truck configurations, typical payloads in timber trucking, the road transportation share of the total industrial roundwood longdistance transportation volume, and the average long-distance transportation distances and costs of industrial roundwood. The study was carried out as a questionnaire survey. The questionnaire was sent to timber transportation logistics experts and research scientists in the 30 countries with the largest industrial roundwood removals in Europe, as well as selected major forestry countries in the world (Argentina, Australia, Brazil, Canada, Chile, China, Japan, New Zealand, South Africa, Türkiye, the United States of America and Uruguay) in February 2022, and closed in May 2022. A total of 31 countries took part in the survey. The survey illustrated that timber trucking was the main long-distance transportation method of industrial roundwood in almost every country surveyed. Road transportation averaged 89% of the total industrial roundwood long-distance transportation volume. Timber truck configurations of 4 to 9 axles with GVW limits of around 30 tonnes to over 70 tonnes were most commonly used. The results indicated that higher GVW limits allowed significantly higher payloads in timber trucking, with the lowest payloads at less than 25 tonnes, and the highest payloads more than 45 tonnes. The average road transportation distance with industrial roundwood was 128 km, and the average long-distance transportation cost in timber trucking was €11.1 per tonne of timber transported. In the entire survey material, there was a direct relationship between transportation distance and transportation costs and an inverse relationship between maximum GVW limits and transportation costs. Consequently, in order to reduce transportation costs, it is essential to maximise payloads (within legal limits) and minimise haul distances. Several measures to increase cost- and energy-efficiency, and to reduce greenhouse gas emissions in road transportation logistics, are discussed in the paper. On the basis of the survey, it is recommended that upto-date statistical data and novel research studies on the long-distance transportation of industrial roundwood be conducted in some countries in the future.
Ključne besede: timber logistics, timber hauling, timber trucking, gross vehicle weight, payload, transportation distance, transportation cost, cost efficiency, limit payload
Objavljeno v DiRROS: 28.02.2024; Ogledov: 136; Prenosov: 63
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2. Flame spread behaviour of Polydimethylsiloxane (PDMS) membranes in 1 g and µg environmentsWilson Ulises Rojas Alva, Frederik Møller-Poulsen, Sze Lok Man, Cameron Creamer, David Hanna, Grunde Jomaas, 2022, izvirni znanstveni članek Povzetek: Diffusion flame behaviour and silica ash (SiO2) production were experimentally studied for various Polydimethylsiloxane (PDMS) membrane thicknesses (0.125 mm to 1.0 mm) in normal gravity and during microgravity flight experiments. The flames were established on vertical samples (300 mm in length) and subjected to either opposed or concurrent forced flows (both laminar and turbulent), assimilating the NASA Test 1 that is in use for spacecraft material selection. The opposed flame spread rate was observed to be steady and could be estimated using classical theory. Under concurrent flow, the flame spread rate was only steady for very high forced flows. The opposed flame-spread rate ranged from 0.5 to 1.5 mm/s, while the concurrent case ranged between 0.1 and 12 mm/s. The transport of silica ash (SiO2) was found to affect the heat balance of the concurrent flame spread in a manner that resulted in unsteady flame spread. For opposed flame spread, on the other hand, the transport of silica ash showed to be irrelevant. The extinction behaviour for the concurrent flame spread was heavily dominated by the transport of silica-ash, while for opposed flames, extinction was due to kinetics (at high forced flows). In microgravity environments, the transport and deposition of silica ash is anticipated to dominate flame spread and near-limit as well. These results suggest that silica-based products might be less flammable in microgravity than other similar materials such as common thermoplastics (PP or PE) used as wire jackets.
Ključne besede: silicone burning, spacecraft fire safety, flame spread, near-limit, silica-ash
Objavljeno v DiRROS: 13.11.2023; Ogledov: 314; Prenosov: 80
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