Prandtl number effects on natural convection heat transfer in concentric and eccentric horizontal cylindrical annuli

The influence of various Prandtl numbers on the laminar convection flow between concentric and vertically eccentric cylinders is studied numerically. To overcome the difficulties associated with the complex physical domains a numerical transformation method is used to map this region on a rectangle. Although two independent computer programs which are based on different formulations of the governing equations were used, nearly identical results were obtained. Local heat transfer results are presented for a wide range of Rayleigh numbers for the first time. Local heat transfer rates are found to depend on the Prandtl number in addition to the Rayleigh number dependence.     

Wärmeleitung in anisotropen zusammengesetzten Körpern beliebiger Gestalt

To investigate the thermal response of composed anisotropic structures, a numerical study has been carried out. By the use of a numerical mapping technique it was possible to handle complex multi-body geometries very efficiently. Due to the transformation method the restriction of the well known finite difference method to simple solution regions is removed. For the iterative solution of the corresponding finite difference equations the Strongly Implicit Procedure (SIP) has been employed. Based on the solution methodology, several numerical examples revealing the effects of anisotropy in thermal conductivity and composite structures are presented.     

Bestimmung von Lanthan, Cer und Neodym mit energiedispersiver R?ntgenfluorescenzanalyse

Zusammenfassung Es wurde eine einheitliche Methode zur Abtrennung und Bestimmung von La, Ce und Nd aus Boden-, Luft- und Pflanzenproben entwickelt. Nach der Abtrennung wurden die Proben in Form von Tabletten und in Form von dünnen Schichten mit Hilfe der EDRFA bestimmt. Die Methode ist erweiterbar auf weitere Lanthanoiden sowie auf U und Th. Die Reproduzierbarkeit des Verfahrens beträgt ± 6%

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Determination of La, Ce and Nd by energy dispersive X-ray fluorescence analysis

Summary A method was developed for the separation and determination of La, Ce and Nd in different environmental samples. After separation, the samples were measured as pellets and as thin layers with EDXRFA. This method can also be used for other rare earths, and for U and Th. The reproducibility of the procedure is ±6%.

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Herrn Prof. Dr. H. Hartkamp zum 60. Geburtstag gewidmet