| 31. |
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| 32. |
- Boström, Kurt, et al.
(författare)
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The origin of iron-rich muds at the Kameni Islands, Santorini, Greece
- 1984
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Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 42:1-4, s. 203-218
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Tidskriftsartikel (refereegranskat)abstract
- Hydrothermal sediments form in several places within the Santorini caldera. The sediments at the most active hot submarine spring (at SW Nea Kameni) consist of 40-48% Fe2O3 and 8-15% SiO2, but only little Al2O3 (0.5-1.6%), P (0.1-0.3%), Mn (100-450 ppm), Sr, Zr, Ba, Zn and V (∼30-200 ppm) and Cu, Ni and Y (∼ 1-30 ppm) are present. The sediments contain more Fe and P and less Si, Al, Mn and many trace elements than sediments formed at less active springs at Palaea Kameni; the differences probably being caused by faster deposition rates of Fe at Nea Kameni and less dilution by rock detritus, which delivers Al, Si and Mn. The Santorini sediments differ much from other exhalative sediments at present or old spreading centers, for example on the East Pacific Rise, in the Red Sea or at En Kafala, which are rich in Mn, Cu, Zn, Ni and Ba. Hydrothermal rock leaching probably occurs at much lower pH-values at Santorini than on the East Pacific Rise, causing a more complete breakdown of the leached rock at Santorini. The very low trace element to iron ratios in the rocks at Santorini, therefore, prevent the hydrothermal solutions there from being very rich in trace elements. The very acid leaching solutions at Santorini are created by extensive oxidation of hydrogen sulfide to sulfuric acid, a process that is readily possible due to the close proximity of the oxygen-rich atmosphere to the top of the magma chamber.
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| 33. |
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| 34. |
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| 35. |
- Cerreta, M.K., et al.
(författare)
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Raman spectroscopic studies of the structure of supersaturated ammonium dihydrogen phosphate solutions
- 1984
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Ingår i: Industrial crystallization 84. - Amsterdam : Elsevier. - 0444424067 ; , s. 233-236
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Konferensbidrag (refereegranskat)abstract
- Raman spectroscopic studies of quiescent under and supersaturated ammonium dihydrogen phosphate (ADP) aqueous solutions were performed on the nu //1 (totally symmetric or breathing mode) and nu //3 (symmetric twist) H//2PO//4 OVER BAR bands as well as for the nu //1 band of solid ADP and solid diammonium hydrogen phosphate (DHP). The splitting of the non-degenerate ADP nu //1 band in concentrated solution is interpreted in terms of a well-ordered quasi-crystalline solution structure. Increases in nu //1 half-width at half-height support this view.
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| 36. |
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| 37. |
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| 38. |
- Doughty, Christine, et al.
(författare)
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Steady flow model user`s guide
- 1984
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sophisticated numerical models that solve the coupled mass and energy transport equations for nonisothermal fluid flow in a porous medium have been successfully used to match analytical results as well as field data for aquifer thermal energy storage (ATES) systems.^Generally these models are expensive and time-consuming to use.^Typically an ATES study is concerned primarily with energy balances and heat flows.^Often the fluid flow field is simple and reaches steady-state rapidly.^As an alternative for this sort of ATES problem the Steady Flow Model (SFM), a simplified but fast numerical model, has been developed.^Rather than solving the mass transport equation to obtain a fluid flow field that varies with time, a steady purely radial flow field is prescribed in the aquifer, and incorporated into the heat transport equation which is then solved numerically.^While the radial flow assumption limits the range of ATES systems that can be studied using the SFM, it greatly simplifies use of this code.^The preparation of input is quite simple compared to that for a sophisticated coupled mass and energy model, and the cost of running the SFM is far cheaper as well.^Furthermore, the simple flow field allows use of a special calculational mesh that eliminates the numerical dispersion usually associated with the numerical solution of convection problems.^The present report defines the problem considered, briefly outlines the algorithm used to solve it, then describes the input and output for the SFM.
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| 39. |
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| 40. |
- Easterling, Kenneth E.
(författare)
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Solidification microstructure of fusion welds
- 1984
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Ingår i: Material Science and Engineering. - 0025-5416. ; 65:1, s. 191-198
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Tidskriftsartikel (refereegranskat)abstract
- The microstructure developed during weld solidification and the effect of the various welding and materials parameters is discussed. It is shown that weld solidification is in several ways fundamentally different from solidification in conventional casting in that it is a dynamic (moving heat source) process in which the `mould' material (the base metal) has approximately the same composition as that of the solidifying metal. The moving arc also has the effect of continuously varying the solidification conditions, e.g. the temperature gradient and degree of convection, in the melt. The additional modifications to microstructure during cooling of the weld metal are also briefly discussed
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