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Ozonbehandling av gulrøtter og moreller - Resultater fra ozonbehandling og lagringsstudie
Get PDFBåde innen produksjon av moreller (moreller) og gulrøtter (Daucus carota subsp. Sativus) er soppsykdommer som kan gi store produksjonstap en utfordring. Det er vist at behandling med ozon kan forlenge holdbarheten av ulike matvarer. I denne studien har vi undersøkt hvordan og hvor lenge moreller og gulrøtter bør behandles med ozonholdig vann. Vi har også gjennomført en lagringsstudie der vi har undersøkt hvordan behandling i ozonholdig vann påvirker kvalitetsegenskaper som smak, lukt og farge på emballerte moreller og gulrot. Studien viste at det er potensiale for å forlenge holdbarhet for både moreller og gulrøtter ved å benytte ozonert vann, men at teknologi og prosess må tilpasses produktet.Ozonbehandling av gulrøtter og moreller - Resultater fra ozonbehandling og lagringsstudiepublishedVersio
Corrosion performance of different alloys exposed to HTL conditions – a screening study
Get PDFThe corrosion and material evaluation study in (a) water-based simulated black liquor and (b) water-based simulated black liquor at super-critical conditions was successful. The conclusion from the testing program was that the most resistant alloy for the defined conditions is the chromium-rich carbon steel candidate P91 (UNS K91560). This is a type of creep strength-enhanced ferritic alloy, which is steel designed to retain strength at high temperatures. The P91 abbreviation represents the material's chemical composition, that is, 9 wt% chromium (Cr) and 1 wt% molybdenum (Mo). Further work is required to conclude the corrosion resistance for the P91 quality at supercritical conditions in the welded condition and to better understand caustic corrosion mechanisms.publishedVersio
Experimental study of fire exposed expanded polystyrene (EPS) insulation protected by selected coverings
Get PDFInsulation products made of expanded polystyrene (EPS) are commonly utilized in buildings. However, Norwegian building regulations restrict the use of such combustible insulation due to an increased risk of fire spread and generation of smoke and toxic gases. Installation of fire protection coverings has been adopted as a mitigation strategy to address these safety risks. Notably, the current regulations lack pre-approved solutions describing what is considered an adequate protection of combustible insulation. The present study investigated the fire protection properties of selected coverings used to protect EPS insulation in inner walls. Eight comparative fire tests were conducted using an indicative fire resistance test furnace. The test specimens consisted of EPS blocks mounted on a wooden frame and covered with one or two layers of selected board coverings. The specimens were positioned vertically within the test furnace, and each fire test lasted for 10 or 15 min. Test results revealed that only two configurations consisting of either two layers of 12.5 mm gypsum boards or a combination of 12 mm oriented strand board (OSB) and 12.5 mm gypsum board showed no evidence of damage to the EPS substrate after a 15-min fire exposure. Consequently, the findings suggest that a total covering thickness of at least 24.5 mm, comprising two layers of boards, is necessary to prevent adverse effects on EPS insulation. Furthermore, fire tests conducted on coverings with introduced damages and defects showed that the affected area around the damages and defects were limited. For the standard EPS substrate, this area extended from 28 mm to 90 mm, while for the fire-retardant EPS substrate from 28 mm to 75 mm after a 10-min fire exposure. These results suggest that minor physical failures in the covering have limited impact on the fire safety of the system.publishedVersio
Operational support framework for maritime autonomous surface ships under onshore operation centers
No full textIn recent years, the concept of Maritime Autonomous Surface Ships (MASSs) has gotten atten tion both from the research community and shipping industry. The recent development in advanced sensing, communication, and control technologies makes it possible to operate such vessels remotely through Onshore Operation Centers (OOCs). However, there are still several challenges that need to be addressed before such ships can be used safely and effectively in ocean environments. To handle these challenges faced by MASSs, a large-scale acceptance procedure from commercial industries and regulatory authorities, an on OOC frame work is proposed in this research study. However, this study is limited to an OOC operational support frame work for operational monitoring, guidance, and support. It shows how the proposed framework will support online MASS operations in ocean environments. This opens the ways to develop and operate the MASS con cept through OOCs to control future vessels remotely by the crew sitting in onshore centers. It will enhance the MASSs technology acceptance both from the technological and regular regulatory perspectives. The study also identifies such challenges and their viable solutions in the aspect of operational support framework as well.acceptedVersio
Volatile matter characterization of birch biochar produced under pressurized conditions
Get PDFThe volatile matter (VM) content and composition of birch biochars produced at 320 °C under elevated pressure (0.1–11 MPa) and constant pressure or constant volume reactor conditions were characterized by thermogravimetry/mass spectrometry (TG/MS) and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). Some of the thermal properties of the biochars and the composition of the VMs varied as a function of the maximal pressure applied during carbonization. The samples prepared at higher pressures released more volatiles up to 320 °C, while the maximal rate of thermal decomposition at around 440 °C showed decreasing tendency with the carbonization pressure. In terms of VM composition, the most apparent effect was the significant increase of the amounts of apoallobetulins from biochars prepared at elevated pressures, which were formed by dehydration, ring closure and rearrangement from the betulin content of birch. The change in the ratio of the evolved guaiacol and 4-methylguaiacol as well as that of syringol and 4-methylsyringol as a function of the maximal pressure of carbonization indicated a modification of the lignin decomposition mechanism. © The Author(s) 2024.publishedVersio
Integration assessment of turquoise hydrogen in the European energy sector
Get PDFTurquoise hydrogen from natural gas pyrolysis has recently emerged as a promising alternative for low-carbon hydrogen production with a high-value pure carbon by-product. However, the implications of this technology on the broader energy system are not well understood at present. To close this literature gap, this study presents an assessment of the integration of natural gas pyrolysis into a simplified European energy system. The energy system model minimizes the cost by optimizing investment and hourly dispatch of a broad range of electricity and fuel production, transmission, and storage technologies, as well as imports/exports on the global market. Norway is included as a major natural gas producer, and Germany as a major energy importer. Results reveal that pyrolysis is economically attractive at modest market shares where the carbon by-product can be sold into high-value markets for 400 €/ton. However, pyrolysis-dominated scenarios that employ methane as a hydrogen carrier also hold promise as they facilitate deep decarbonization without the need for vast expansions of international electricity, hydrogen, and CO2 transmission networks. The simplicity and security benefits of such pyrolysis-led decarbonization pathways justify the modest 11 % cost premium involved for an energy system where natural gas is the only energy trade vector. In conclusion, there is a strong case for turquoise hydrogen in future energy systems and further efforts for commercialization of natural gas pyrolysis are recommended.publishedVersio
Upgrading and Enhancement of Recycled Polyethylene Terephthalate with Chain Extenders: In-Depth Material Characterization
Get PDFChemical chain extenders (CEs) can be used to restore the properties of recycled low-molecular-weight polyethylene terephthalate (PET). The aim of this work is to investigate the influence of the type and concentration of the CEs Joncryl and pyromellitic dianhydride (PMDA) on the viscosity and other rheological properties with a unique combination of different methods based on industrial samples originating from recycled PET bottles and trays. The resulting chain-extended thermoplastics were characterized by a combination of differential scanning calorimetry, viscometry, cone plate rheometry, pyrolysis-gas chromatography-mass spectroscopy, optical photo-thermal infrared spectroscopy, 13 C solid-state-and 1 H NMR liquid spectroscopy, and size exclusion chromatography. For a recycled PET mixture containing bottle and tray materials, our investigations have shown that a significantly better effect for chain elongation can be achieved with Joncryl compared to PMDA. This can presumably be attributed to water molecules formed during the use of PMDA, which accelerate the degradation of PET. The storage modulus values are therefore significantly higher for the samples with Joncryl compared to PMDA. The results of this study show that chain extension with Joncryl proceeds better compared to the reaction with PMDA.publishedVersio
Fast light alloy stamping technology (FAST) for manufacturing lightweight pressings from dissimilar aluminium alloy-tailor welded blanks
Get PDFDissimilar aluminium alloy-tailor weld blanks (DA-TWB) are increasingly being used in transportation industries due to their significant benefit in reinforcing vehicle structures as well as improving lightweight performance. Hot stamping technologies enabling the manufacture of lightweight pressings from DA-TWB have yet to be developed and be widely implemented. In the present research, a unified automated production system was developed to integrate the functions of heating, blank transfer, forming and post-form heat treatment, and automatically conduct hot stamping of materials under various conditions with high accuracy, enabling a forming temperature of up to 650 °C, a heating rate of up to 200 °C/s, a blank transfer speed of up to 200 mm/s, a forming speed of up to 1500 mm/s and a die closing force of up to 50 kN. The effects of processing parameters, including heating rate ranging from 1 to 150 °C/s, forming temperature ranging from 200 to 500 °C and forming speed ranging from 50 to 350 mm/s, on the post-form hardness/strength, microstructure and springback of individual AA6082 and AA7075 aluminium alloys were subsequently studied to obtain an optimised processing window for forming the DA-TWB joined by friction stir welding, which was formed by using the developed production system. From the studies, 95 % of the T6 temper's hardness was achieved and metastable strengthening phases were dispersedly distributed in both alloys (i.e. β″ for AA6082 and η′ for AA7075) with negligible springback of less than 2° by using a heating rate of 50 °C/s, a forming temperature of 300 °C and a forming speed of more than 250 mm/s. In addition, the forming process of the DA-TWB was finite element simulated for thermal and mechanical analysis. It was validated that Fast light Alloy Stamping Technology (FAST) with an optimised processing window was capable of providing superior strength-springback behaviour at a production cycle time of less than 10 s.publishedVersio
Trade-off between drag and catch performance when designing zooplankton trawls
Get PDFThe aquaculture sector is in pursuit of sustainable and cost-effective raw materials for feed, and the copepod Calanus finmarchicus is a marine zooplankton species of commercial interest because of its high abundance in northern areas. These copepods have the potential to meet the demand for vast quantities of marine raw materials. However, the lack of an energy- and catch-efficient trawl technology has limited the development of this fishery. Therefore, this study investigated the effect of two central trawl net design parameters mesh size and taper angle to identify which values that provide optimal trade-off balance between gear drag and catch efficiency. We conducted flume tank experiments using a series of plankton nets varying in mesh size (250–1000 μm), solidity ratio (0.54–0.76), and taper angle (5°– 30°) to acquire data on gear drag. The same nets were then used in fishing trials to obtain data on their catch performance. This study shows that zooplankton nets with a mesh size of approximately 500 μm and a low taper angle of about 5° provided the best trade-off between drag and catch performance.publishedVersio
Characterizing street trees in three metropolises of central China by using Street View data: From individual trees to landscape mapping
Get PDFStreet trees can benefit urban spaces, and the characterization of them is a basis for evaluating their functions and proper management. In this paper, we speculate that Street View imagery-based measurement favors characterizing street trees from individual tree sizes and growth status to spatial mapping and risk region identification at multiple city levels. Using Wuhan, Changsha, and Nanchang as examples, nearly 6000 sites and over 111,000 Baidu Street View (BSV) images were used to measure tree sizes, growth status, and vertical structure. Together with BSV-derived tree data, we also calculated the street-view greenness index (GVI) and the Normalized Difference Vegetation Index (NDVI) from remote sensing data, and then city-level spatial mapping was produced to identify risk regions for urban afforestation. The results showed that BSV measurement could compare city-level street trees, i.e., Changsha had a 1.2–1.3-fold higher diameter, tree height, and canopy size than the lowest at Nanchang; Changsha had the highest GVI, but the lowest NDVI; while Nanchang had the lowest GVI, but the highest NDVI, showing different significance between street-view and remote-sensing greenness. BSV data could identify urbanization effects, i.e., the tree sizes decreased from the urban center to the edge, and three cities showed the same pattern. By using BSV data, the growth status score was summarized from leaf blade color, tree-supported, dieback, and dead-tree percents, and thereafter, urbanization-induced decreases of growth status scores can be observed from the city center to the suburbs. At the same urban-rural gradient, BSV data found the vertical structure tended to be complex, and the sky and middle GVI decreased while the ground GVI rose in all three cities in general. The BSV data made landscape mapping available, and the map can be used to identify risk areas of big-sized tree conservation, health problems, greenness deficiency, and the over-simplified forest structure within a city or among different cities. Together with BSV-derived street development data, complex associations between tree characteristics and geo-climates and street social development could be decoupled by redundancy ordination. In general, streets with more pedestrians were often accompanied by taller, larger, healthier trees, more complex communities, and an increasing sky/ground ratio of GVI greenery. Our findings highlighted that street-view data could be used to assess street tree characteristics, geographic distribution, and possible associations with other factors, favoring the city-level urban tree inventory from individuals to the landscape for urban tree management and policymaking.publishedVersio