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| 2. |
- Ion, John, et al.
(författare)
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Process diagrams for laser beam welding of carbon manganese steels
- 1996
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Ingår i: Welding Journal. - 0043-2296. ; 75:7, s. 225-
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Tidskriftsartikel (refereegranskat)abstract
- Diagrams are presented which illustrate the ranges of process variables that can be used to produce acceptable laser welds in carbon manganese steels. The most practical type uses axes of beam power and welding speed. An empirical operating window is displayed, which describes the limits of full joint penetration welding for a particular steel and plate thickness. Theoretical contours of heat-affected zone (HAZ) hardness, established using analytical models, are also displayed on the diagram. Appropriate combinations of laser beam power and welding speed can thus be selected. A more comprehensive diagram uses axes of carbon equivalent and absorbed laser beam energy, on which theoretical HAZ hardness contours are displayed. The effects of changes in steel composition and welding variables on HAZ hardness can thus be assessed. Model results agree well with experimental data, as well as more sophisticated predictive methods. The diagrams provide guidance on the selection of steel composition and beam parameters during the initial stages in the development of procedures for laser welding of carbon manganese steels.
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| 3. |
- Navarro-Pardo, F., et al.
(författare)
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Nanofiber-supported CuS nanoplatelets as high efficiency counter electrodes for quantum dot-based photoelectrochemical hydrogen production
- 2017
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Ingår i: Materials Chemistry Frontiers. - : Royal Society of Chemistry. - 2052-1537. ; 1:1, s. 65-72
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Tidskriftsartikel (refereegranskat)abstract
- We developed a hierarchically assembled hybrid counter electrode (CE) based on copper sulfide (CuS) nanoplatelets grown on polymer nanofibers. The resulting CE was used in a quantum dot (QD)-based photoelectrochemical (PEC) system for H2 generation in the presence of sacrificial agents (S2−/SO32−). The concept is to increase the specific surface area of the CE, aiming at maximizing charge exchange at the electrode, which boosts efficient generation of H2 and to obtain a stable structure for long-term operation of the device. Structural and morphological characterization indicated the presence of a covellite crystalline phase (CuS). PEC tests showed that the CuS nanoplatelets grown in the CEs could replace Pt CEs in either visible-active or near infrared (NIR)-active QD-based PEC systems. Specifically, saturation of the photocurrent density (∼7.5 mA cm−2) occurred at ∼0.6 V versus the RHE, when using a NIR QD-based TiO2 photoanode and a nanofiber-supported CuS as the CE. Stability tests of the nanofiber-supported CuS CE showed that 85% of the initial photocurrent density was maintained after ∼1 h, which is similar to that obtained with the Pt foil CE (86%). In contrast, CuS nanostructures directly deposited on FTO glass without nanofibers (CuS/FTO CE) exhibited poor stability. CuS/FTO CE degraded quickly, showing a 90% drop in the initial photocurrent within 200 s testing whereas a 14% drop in the initial photocurrent was observed for the CuxS on brass within 10 min of testing. Our new nanofiber supported-CuS CE stands out due to its higher performance compared to brass and its similar stability compared to Pt during long term PEC operation. Additionally, our hybrid CE showed a better catalytic performance than the Pt CE and good stability in cyclic voltammetry tests. These results demonstrate that the nanofiber-supported CuS is a promising cost effective alternative to Pt as a highly efficient CE for PEC H2 generation
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| 4. |
- Raju, G. Bhaskar, et al.
(författare)
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Shear-flocculation of quartz
- 1991
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Ingår i: International Journal of Mineral Processing. - 0301-7516 .- 1879-3525. ; 32:3-4, s. 283-294
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Tidskriftsartikel (refereegranskat)abstract
- The present work deals with the shear-flocculation of quartz in aqueous solutions of dodecylamine chloride. The variables studied include pH, concentration of the amine, size of the coarse particles, stirring speed and time. The zeta potentials were correlated with flocculation behaviour. It was observed that particle hydrophobicity and pH were most important since the dodecylamine chloride-solution reactions are pH-and concentration-dependent.
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| 5. |
- Rao, K. Hanumantha, et al.
(författare)
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Size effect of the mode II fracture toughness of rock
- 1999
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Ingår i: Rock mechanics for industry. - Rotterdam : Balkema Publishers, A.A. / Taylor & Francis The Netherlands. - 9058091007 ; , s. 1117-1123
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Konferensbidrag (refereegranskat)abstract
- A new method, compression-shear test, has been developed for determining the mode II fracture toughness K (sub IIC) of rock. The effect of the specimen thickness B, the dimensionless notch length a/W as well as the notch inclination angle alpha on the determination of K (sub IIC) has been experimentally studied. The results show that the apparent mode II fracture toughness K (sub c) decreases as B and a/W increase and becomes constant when B> or =70 mm (i.e. cubic specimen) and a/W>0.5. The K (sub c) is almost independent of alpha in the range of 65 degrees -75 degrees . The constant K (sub c) is about 2-3 times that of mode I fracture toughness K (sub IC) and can be considered as the true mode II fracture toughness K (sub IIC) of rock.
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| 6. |
- Rao, Q.H., et al.
(författare)
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Mode II fracture toughness testing of rock
- 1999
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Ingår i: Comptes-rendus / 9 Congrès international de mécanique de roches, Paris, France 1999. - Rotterdam : Balkema Publishers, A.A. / Taylor & Francis The Netherlands. - 905809071X ; , s. 731-734
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Konferensbidrag (refereegranskat)
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| 7. |
- Subrahmanyam, T V, et al.
(författare)
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Variables in the shear flocculation of galena
- 1990
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Ingår i: Sulphide deposits. - London : The Institution of Mining and Metallurgy. - 1870706234 ; , s. 223-231
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Like froth flotation the shear flocculation is governed by the physical, chemical and geometrical variables. Among the important factors which influence the particle aggregation are the particle size, hydrophobicity, charge and the intensity of agitation. The present paper investigates the effect of different variables on the shear flocculation of (1). galena and (2). synthetic PbS. Since flocculation is influenced both by the charge and the hydrophobicity of the particle the zeta potentials were measured for different experimental conditions. The reaction mechanisms of PbS surfaces in aqueous solutions are examined based on the results of electrokinetic-and potentiometric titration- studies. In comparison to conventional flotation, higher recoveries were obtained with shear flocculated aggregates. The results are discussed.
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| 8. |
- Sun, Z., et al.
(författare)
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Laser welding of dissimilar metal combinations
- 1995
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 30:17, s. 4205-4214
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Tidskriftsartikel (refereegranskat)abstract
- The ability to manufacture a product using a number of different metals and alloys greatly increases flexibility in design and production. Properties such as heat, wear and corrosion resistance can be optimized, and benefits in terms of production economics are often gained. Joining of dissimilar metal combinations is, however, a challenging task owing to the large differences in physical and chemical properties which may be present. Laser welding, a high power density but low energy-input process, provides solutions to a number of problems commonly encountered with conventional joining techniques. Accurate positioning of the weld bead, rapid heating and cooling, low distortion, process flexibility, and opportunities for product redesign are its principal characteristics. The review describes the principles underlying laser welding of dissimilar metal combinations and highlights the above benefits in a number of practical applications. It is concluded that there is potential for its application in many industrial sectors.
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| 9. |
- Sun, Z., et al.
(författare)
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Rock joint compliance tests for compression and shear loads
- 1985
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Ingår i: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. - : Elsevier BV. - 0148-9062 .- 1879-2073. ; 22:4, s. 197-213
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Tidskriftsartikel (refereegranskat)abstract
- A series of compression and shear tests were conducted at large scale on joint surfaces in granite and slate specimens, with special equipment being used to isolate the deformations of the joints from those of the rock material. The matrix of compliance components for a rock joint is discussed in relation to these standard tests and it is shown that one pair of compliance components can be determined from a compression test and a second pair from a shear test. For the compression tests, the test results indicate a pattern of decreasing compliance with load, an increase in compliance with initial aperture, and high levels of recoverability of deformation. In the shear tests, the curves for the relative displacements indicate there are three zones of different behavior, elastic, transition and sliding
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