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- Mellin, Pelle, et al.
(författare)
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Evaluating flowability of additive manufacturing powders, using the Gustavsson flow meter
- 2017
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Ingår i: Metal Powder Report. - : Elsevier Ltd. - 0026-0657 .- 1873-4065. ; 72:5, s. 322-326
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Tidskriftsartikel (refereegranskat)abstract
- The Gustavsson flow meter (including standard ISO-13517) is in this paper used to measure flow rate of fine AM powders. In the current paper, the results are compared to the Hall flow meter and a Freeman FT4 powder rheometer in terms of success of measuring these AM powders. The range of possible powders to measure is smaller with Gustavsson flow meter; but in this range, the difference in flow time is greater compared to the Hall flow meter. Compared to using the rheometer, the Gustavsson flow meter is faster and simpler to use; however, other powder-aspects are evaluated since little correlation was found. For the powders in this paper, all methods of characterizing the flowability could distinguish between (1) two alloys, and (2) if the alloys were new or used (in SLM), and (3) if they were dried or non-dried.
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- Vattur Sundaram, Maheswaran, 1987, et al.
(författare)
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Vacuum sintering of chromium alloyed powder metallurgy steels
- 2019
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Ingår i: Metal Powder Report. - : Mark Allen Group. - 0026-0657 .- 1873-4065. ; 74:5, s. 244-250
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Tidskriftsartikel (refereegranskat)abstract
- Modern developments in vacuum furnace technologies have led to an increased interest in vacuum sintering of powder metallurgy (PM) steel components owing to the robustness, productivity and the possibility to integrate heat-treatment into the process at an attractive cost. In the present study, the potential for vacuum sintering of chromium-alloyed PM steels and the effect of the vacuum level on the final properties of the components are evaluated. The studies were performed on Fe-1.8 wt.% Cr powder and the sintering experiments were performed in a dilatometer. Four different vacuum levels: 10, 1, 10−2 and 10−4 mbar were studied and the effect of density and carbon content were also examined. The results indicate an efficient oxide reduction and process robustness at intermediate vacuum levels whereas high-temperature sintering in high vacuum brings the risk of Cr-sublimation. Furthermore, industrial trails were performed at 10 and 1 mbar vacuum levels and their mechanical properties were evaluated. Vacuum sintering proved to be an attractive alternative to process Cr-alloyed steel powders.
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- Yang, Shun-Han, 1987, et al.
(författare)
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A comparison of coupled and de-coupled simulation procedures for the fatigue analysis of WEC mooring lines
- 2016
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Ingår i: Ocean Engineering. - : Elsevier BV. - 0029-8018 .- 1873-5258. ; 117:1, s. 332-345
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Tidskriftsartikel (refereegranskat)abstract
- Mooring systems for floating wave energy converters (WECs) must be designed to survive the cyclical loads and motions to which they are subjected as a result of the wave load-WEC interaction and the motions of the WEC in the random elevation of the sea surface. The current study compares simulation procedures for the fatigue analysis of WEC moorings. The objective is to suggest a simulation procedure suitable for an extensive study of the behaviour of WEC systems and thus for the fatigue analysis of mooring lines. A cylindrical, floating WEC with four spread mooring lines is chosen as case study. The dynamics of the WEC system are simulated and analysed using both coupled and de-coupled models in the time-domain. Four types of simulation procedures are compared using commercial software, DNV DeepC, and an in-house solver, MooDy. A systematic fatigue response analysis based on variations of the numerical and physical parameters is conducted. The results are compared with respect to the fatigue damage calculated using the stress-based approach and the rainflow counting method. The simulation procedure using a coupled model is suggested as the preferred numerical method for capturing the interaction between the components of WEC system, which is proven to be crucial for the fatigue damage evaluation of mooring lines.
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- Dimitrakopoulou, Anastasia, et al.
(författare)
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Synthesis, structure and interactions with DNA of novel tetranuclear, [Mn-4(II/II/II/IV)] mixed valence complexes
- 2008
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Ingår i: Journal of Inorganic Biochemistry. - : Elsevier BV. - 1873-3344 .- 0162-0134. ; 102:4, s. 618-628
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Tidskriftsartikel (refereegranskat)abstract
- Reaction of Mn(II) with phenoxyalkanoic acids and di-2-pyridyl ketone oxime (Hpko) leads to neutral tetranuclear complexes of the general formula Mn-4(O)(pko)(4)(phenoxyalkanoato)(4) (phenoxyalkanoic acids: H-mcpa = 2-methyl-4-chloro-phenoxy-acetic acid, H-2,4,5-T = 2,4.5-trichloro-phenoxy-acetic acid or H3,4-D = 3,4-dichloro-phenoxy-acetic acid). The compounds were synthesized by adding di2-pyridyl ketone oxime to MnCl2 in the presence of the sodium salts of the alkanoic acids in methanol. The crystal structure of Mn-4(II/II/ II/IV)(O)(pko)4(()2,4,5-T)(4) . 2.5CH(3)OH . 0.25H(2)O 1 shows that the complex consists of a [Mn-4( mu(4)-O)](8+) core with a Mn(IV) and 3 Mn(II) ions in octahedral environment and a mu(4)-O atom bridging the four manganese ions. Spectroscopic studies of the interaction of these tetranuclear clusters with DNA showed that these compounds bind to dsDNA. The binding strength of the Mn-4(II/II/II/ IV)(O)(pko)(4)(2,4,5-T)(4) complex for calf thymus DNA is equal to 1.1 X 10(4) M-1. Among the deoxyribonucleotides they bind preferentially to deoxyguanylic acid (dGMP). Competitive studies with ethidium bromide (EthBr) showed that the Mn-4(II/II/II/ IV)(O)(pko)(4)(2,4,.5-T)(4) complex exhibited the ability to displace the DNA-bound EthBr indicating that the complex binds to DNA via intercalation in strong competition with EthBr for the intercalative binding site. Additionally, DNA electrophoretic mobility experiments showed that all three complexes, at low cluster concentration, are obviously capable of binding to pDNA causing its cleavage (relaxation) at physiological pH and temperature. At higher cluster concentration, catenated dimer forms of pDNA was formed.
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