TY  - JOUR
A1  - Tippkötter, Nils
A1  - Roikaew, Wipa
A1  - Ulber, Roland
A1  - Hoffmann, Alexander
A1  - Denzler, Hans-Jörg
A1  - Buchholz, Heinrich
T1  - Paracoccus denitrificans for the effluent recycling during continuous denitrification of liquid food
JF  - Biotechnology Progress
N2  - Nitrate is an undesirable component of several foods. A typical case of contamination with high nitrate contents is whey concentrate, containing nitrate in concentrations up to 25 l. The microbiological removal of nitrate by Paracoccus denitrificans under formation of harmless nitrogen in combination with a cell retention reactor is described here. Focus lies on the resource-conserving design of a microbal denitrification process. Two methods are compared. The application of polyvinyl alcohol-immobilized cells, which can be applied several times in whey feed, is compared with the implementation of a two step denitrification system. First, the whey concentrate's nitrate is removed by ion exchange and subsequently the eluent regenerated by microorganisms under their retention by crossflow filtration. Nitrite and nitrate concentrations were determined by reflectometric color measurement with a commercially available Reflectoquant® device. Correction factors for these media had to be determined. During the pilot development, bioreactors from 4 to 250 mg·L-1 and crossflow units with membrane areas from 0.02 to 0.80 m2 were examined. Based on the results of the pilot plants, a scaling for the exemplary process of denitrifying 1,000 tons per day is discussed.
Y1  - 2010
U6  - http://dx.doi.org/10.1002/btpr.384
SN  - 8756-7938
VL  - 26
IS  - 3
SP  - 756
EP  - 762
PB  - Wiley
CY  - Hoboken, NJ
ER  - 
TY  - JOUR
A1  - Pieper, Martin
A1  - Klein, Peter
T1  - Numerical solution of the heat equation with non-linear, time derivative-dependent source term
JF  - International Journal for Numerical Methods in Engineering
N2  - The mathematical modeling of heat conduction with adsorption effects in coated metal structures yields the heat equation with piecewise smooth coefficients and a new kind of source term. This term is special, because it is non-linear and furthermore depends on a time derivative. In our approach we reformulated this as a new problem for the usual heat equation, without source term but with a new non-linear coefficient. We gave an existence and uniqueness proof for the weak solution of the reformulated problem. To obtain a numerical solution, we developed a semi-implicit and a fully implicit finite volume method. We compared these two methods theoretically as well as numerically. Finally, as practical application, we simulated the heat conduction in coated aluminum fibers with adsorption in the zeolite coating. Copyright © 2010 John Wiley & Sons, Ltd.
Y1  - 2010
U6  - http://dx.doi.org/10.1002/nme.2937
SN  - 0029-5981
VL  - 84
IS  - 10
SP  - 1205
EP  - 1221
PB  - Wiley
CY  - Chichester
ER  - 
TY  - JOUR
A1  - Haselgruber, Nikolaus
A1  - Mautner, Karin
A1  - Thiele, Jan
T1  - Usage Space Analysis for Reliability Testing
JF  - Quality and Reliability Engineering International
N2  - During the development process of a complex technical product, one widely used and important technique is accelerated testing where the applied stress on a component is chosen to exceed the reference stress, i.e. the stress encountered in field operation, in order to reduce the time to failure. For that, the reference stress has to be known. Since a complex technical product may fail regarding numerous failure modes, stress in general is highly dimensional rather than scalar. In addition, customers use their products individually, i.e. field operation should be described by a distribution rather than by one scalar stress value. In this paper, a way to span the customer usage space is shown. It allows the identification of worst case reference stress profiles in significantly reduced dimensions with minimal loss of information. The application example shows that even for a complex product like a combustion engine, stress information can be compressed significantly. With low measurement effort it turned out that only three reference stress cycles were sufficient to cover a broad range of customer stress variety.
Y1  - 2010
U6  - http://dx.doi.org/10.1002/qre.1155
SN  - 1099-1638
N1  - Special Issue: Business and Industrial Statistics: Developments and Industrial Practices in Quality and Reliability
VL  - 26
IS  - 8
SP  - 877
EP  - 885
PB  - Wiley
CY  - New York
ER  -