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- Ghorbani, Sasan, et al.
(författare)
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A new rock hardness classification system based on portable dynamic testing
- 2022
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Ingår i: Bulletin of Engineering Geology and the Environment. - : Springer. - 1435-9529 .- 1435-9537. ; 81:5
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Tidskriftsartikel (refereegranskat)abstract
- Hardness is one of the critical physical characteristics of minerals and rocks, which indicates the resistance of the rock to penetration, scratch, or permanent deformation. As a basic concept, rock hardness has a significant role in rock mechanics and geological engineering and is an appropriate diagnostic tool for the classification of minerals and rocks. The main purpose of this study is to guide rock engineers to measure the rock hardness faster, easier, and more accurately using Leeb’s dynamic hardness test. Accordingly, this paper presents a new rock hardness classification system based on the Leeb dynamic and portable hardness testing method. It is a well-known method for its fast and straightforward procedure testing equipment. A set of 33 different rock types were collected and tested during this study. Next, in-depth microscopic mineralogical studies were performed to determine the precise Mohs hardness value. The Mohs hardness was considered the leading hardness benchmark during the experimental studies, and the Leeb hardness was adopted to classify based on this hardness. A series of laboratory studies and statistical analysis was performed to predict the Shore and Vickers hardness using Leeb hardness. Finally, based on the comparative studies, it is recommended to classify the rocks considering the Leeb hardness method in six different categories: extremely soft (1–250), soft (250–450), moderately soft (450–750), moderately hard (750–850), hard (850–920), and extremely hard (920–1000). The provided classification could be useful in a vast range of rock engineering applications, especially for feasibility studies of rock engineering projects and engineering geology.
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| 7. |
- Wollheim, F. A.
(författare)
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Nanna Svartz (1890–1986) : Die erste Frau auf einem medizinischen Lehrstuhl in Schweden
- 2017
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Ingår i: Zeitschrift für Rheumatologie. - : Springer Science and Business Media LLC. - 0340-1855 .- 1435-1250. ; 76:9, s. 813-819
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Tidskriftsartikel (refereegranskat)abstract
- Nanna Svartz was a charismatic character who played a significant role in Swedish medicine in the mid-twentieth century. As one of five brothers and sisters, she escaped an early death from tuberculosis. She reached 96 years of age. Her diligence and sense of duty were legendary, along with her ambition to fully prove herself as “the first female professor”. She inherited a certain insecurity from her father that led to her difficulty in taking criticism. Despite extensive academic obligations, she worked as a treating doctor for 55 years and always took her time with her patients, especially if they held important public positions. Nanna was honoured several times in her lifetime. Among others, she was a member of the Leopoldina, the National Academy of Germany, and received many honorary doctorates, for example, from Rockefeller College (USA) and the Åbo University (Turku, Finland). She was an honorary member of over 40 scientific societies. Underneath the new auditorium in the Karolinska Institute, a restaurant and a street in her home town of Västerås bear her name. An annual international Nanna Svartz Lecture is held by the Swedish Society for Rheumatology, and a Nanna Svartz Prize is awarded annually to a deserving young Swedish rheumatologist.
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| 8. |
- Wollheim, Frank, et al.
(författare)
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Die Osteoarthritis (Arthrose) geht uns alle an
- 2003
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Ingår i: Zeitschrift für Rheumatologie. - : Springer Science and Business Media LLC. - 0340-1855 .- 1435-1250. ; 62:4, s. 406-408
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Tidskriftsartikel (refereegranskat)
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| 9. |
- Campbell, Ian, et al.
(författare)
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The relation between the age at diagnosis of problem behaviors related to aggression and distal outcomes in Swedish children
- 2019
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Ingår i: European Child and Adolescent Psychiatry. - : Springer. - 1018-8827 .- 1435-165X. ; 28:7, s. 899-911
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Tidskriftsartikel (refereegranskat)abstract
- Severe childhood aggressive behaviors are known to predict negative outcomes later in life; however, little is known about the effect of when in childhood aggression problems are diagnosed. While an earlier first diagnosis of problematic aggressive behavior might be associated with increased severity and, thus, worse outcomes, it is also possible that an earlier diagnosis affords an earlier start of treatment programs or indicates that greater attention is being paid to behavioral problems, thus resulting in attenuation of the severity of childhood aggression's impact on distal outcomes. The current study analyzed data from the population-based Swedish Data Registries, which include data on all children formally diagnosed by the Swedish medical system with a wide range of aggression problems between ages 8 and 18 (N = 5816) during the years 1987-2013, along with a matched control. Time-to-event analyses investigated whether the age at time of diagnosis affects later life outcomes while controlling for relevant confounders. Results show that for both boys and girls, those with a later diagnosis had lower average incomes (regression coefficient b = - 0.055, p < 0.005) and a higher probability of having a criminal record (odds ratio 1.126, p < 0.005) than children with earlier diagnoses. The effect on suicide attempts was not significant after correcting for multiple testing (odds ratio 1.264, p = 0.016). Grade score was not significantly affected. The results warrant further research concerning the potential advantage of earlier diagnoses, especially concerning generalizability beyond the Swedish population.
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- Henderson, Pamela, et al.
(författare)
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In-situ fireside corrosion testing of superheater materials with coal, wood and straw fuels for conventional and asvanced steam temperatures
- 2005
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Ingår i: VGB PowerTech. - Essen, Germany : VGB PowerTech eV. - 1435-3199. ; 84:6, s. 53-59
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Tidskriftsartikel (refereegranskat)abstract
- An increase in the steam temperature of a power station increases the electrical efficiency of the turbine. This in turn leads to a reduction in the cost of electricity and in environmental emissions produced per unit of electricity generated. However, higher steam temperatures give rise to more aggressive corrosive environments and the choice of material becomes more important. In addition, the aggressiveness of the fuels also depends on their chemical compositions. As part of a European research programme (COST 522) fireside corrosion tests of superheater and waterwall materials have been performed in-situ in industrial boilers or combustion test facilities, simulating conventional and higher steam temperatures. The fuels used were, straw, wood (logging residues) and coal. Goals were set at different maximum steam temperatures and lifetimes according to the fuel. The targets were: coal 650°C/100,000 h, wood 580°C/40,000 h and straw 580°C/20,000 h .A wide range of materials was tested. An overriding constraint was that the materials must be economically viable and not impose exceptional fabrication requirements. Some materials were tested in a number of combustion environments, allowing useful comparisons to be made. The results showed that for a given superheater alloy, temperature and fuel, the corrosion rate depended on the alloy’s position in a superheater bank. Tubes on the outside, exposed to the flue gas, corroded faster than those positioned deeper in a bank. Tubes experiencing a greater heat flux will corrode more rapidly. Poorly controlled combustion will also increase corrosion. Straw was much more corrosive than wood (logging residues). The difference in corrosiveness increased with increasing temperature above a metal temperature of about 520°C. The corrosion rates of the alloys tested during wood-firing were only a little higher than those from firing coal with a medium to high chlorine content. Straw and wood are often collectively known as “biomass”, but the corrosion they cause can vary by a factor of 5 or more. No difference could be found in the fireside corrosion rates of the steels TP 347H and TP 347HFG, when tested under similar conditions. Esshete 1250 also showed similar fireside corrosion rates to347 instraw and wood boilers and at temperatures below 650°Cin coal boilers. Several alloys were identified to resist corrosion in coal-fired plant at metal temperatures of680°C(steam temperatures650°C) and high heat fluxes. Adequate high temperature creep strength remains more problematic. At lower heat fluxes (resulting in lower corrosion rates) more candidate alloys exist. It is expected that the goals set can be achieved with the use of suitable alloys in the case of wood, waste and coal. For wood (logging residues) TP347, Esshete 1250 and 50Ni50Cr coatings showed sufficient corrosion resistance at the target temperatures. In the coal case HR3C fulfills the requirements of strength and corrosion resistance with a high heat flux and Super 304H and SAVE 25 if the heat flux is low. HR11N and IN671 are suitable for use as claddings on a substrate with the appropriate creep strength. The goal set for straw firing was ambitious, a steam temperature of580°C, and in this case a combination of material, combustion technology and boiler design are needed.
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