Stefan Diehl 

Associate Professor in Applied Mathematics (Docent i tillämpad matematik)

Centre for Mathematical Sciences
Lund University/Lund Institute of Technology
P.O. Box 118
SE-221 00 Lund
SWEDEN

Room: 551A
Direct phone: +46 46 222 0920
Dept phone: +46 46 222 8537
Fax: +46 46 222 4010
E-mail: diehl@maths.lth.se

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Miscellaneous (in Swedish)

Min docentföreläsning om modellering av trafikflöde, september 2006

Jag har skrivit en bok Inledande geometri för högskolestudier (innehåll) som ges ut av Studentlitteratur.

Förslag på examensarbeten

Sedimentering av biologiskt slam – parameterkalibrering av PDE
Simulering av vattenreningsverk med ODE och PDE
Tredimensionell rekonstruktion av tvådimensionell uppklippt sfärisk yta

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Research

Interests

• non-linear conservation laws and convection-diffusion equations with discontinuous coefficients
• identification of constitutive relations in PDE models
• modelling, simulation and control of the separation process continuous sedimentation, which can be found in, for example, most wastewater treatment plants, the mineral, pulp-and-paper, food and chemical industries
• modelling, simulation and control of the activated sludge process, which can be found in most wastewater treatment plants
• other applications, for example, traffic flow

Old stuff

Swe: En mycket kortfattad beskrivning i populär form av kontinuerlig sedimentering och min doktorsavhandling (1995).
Lecture notes containing an introduction to the scalar conservation law (1996).

Doctoral thesis

Stefan Diehl: Conservation Laws with Application to Continuous Sedimentation, Lund University, ISBN 91-628-1632-2 (1995)

Journal publications

If you are interested in a publication that you cannot find in the links below, please send me an email.

1. S. Diehl: On scalar conservation laws with point source and discontinuous flux function. SIAM J. Math. Anal., 26(6):1425-1451, 1995. Submitted version.
2. S. Diehl: Scalar conservation laws with discontinuous flux function: I. The viscous profile condition.Comm. Math. Phys., 176:23-44, 1996. Submitted version.
3. S. Diehl, Nils-Olof Wallin: Scalar conservation laws with discontinuous flux function: II. On the stability of the viscous profiles. Comm. Math. Phys., 176:45-71, 1996.
4. S. Diehl: A conservation law with point source and discontinuous flux function modelling continuous sedimentation. SIAM J. Appl. Math., 56(2):388-419, 1996.
5. U. Jeppsson and S. Diehl: An evaluation of a dynamic model of the secondary clarifier. Water Sci. Tech., 34(5-6):19-26, 1996.
6. U. Jeppsson and S. Diehl: On the modelling of the dynamic propagation of biological components in the secondary clarifier. Water Sci. Tech., 34(5-6):85-92, 1996.
7. S. Diehl: Dynamic and steady-state behaviour of continuous sedimentation. SIAM J. Appl. Math., 57(4):991-1018, 1997.
8. S. Diehl: Continuous sedimentation of multi-component particles.Math. Meth. Appl. Sci.,20:1345-1364, 1997.
9. S. Diehl and U. Jeppsson: A model of the settler coupled to the biological reactor. Water Res., 32(2):331-342, 1998.
10. S. Diehl: On bondary conditions and solutions for ideal clarifier-thickener units. Chem. Eng. J., 80:119-133, 2000. (A conference talk in 1999.)
11. S. Diehl: Operating charts for continuous sedimentation I: Control of steady states. J. Eng. Math., 41:117-144, 2001. (Final draft)
12. S. Diehl: Operating charts for continuous sedimentation II: Step responses. J. Eng. Math., 53:139-185, 2005. (Final draft)
13. S. Diehl: Operating charts for continuous sedimentation III: Control of step inputs. J. Eng. Math., 54:225-259, 2006. (Final draft)
14. S. Diehl: Estimation of the batch-settling flux function for an ideal suspension from only two experiments. Chem. Eng. Sci., 62:4589-4601, 2007. http://dx.doi.org/10.1016/j.ces.2007.05.025
15. S. Diehl: Operating charts for continuous sedimentation IV: Limitations for control of dynamic behaviour. J. Eng. Math., 60:249-264, 2008. (Final draft)
16. S. Diehl: A regulator for continuous sedimentation in ideal clarifier-thickener units. J. Eng. Math. 60:265-291, 2008. (Final draft)
17. S. Diehl: The solids-flux theory – confirmation and extension by using partial differential equations. Water Res. 42:4976-4988, 2008. http://dx.doi.org/10.1016/j.watres.2008.09.005
18. S. Diehl: A uniqueness condition for nonlinear convection-diffusion equations with discontinuous coefficients. J. Hyperbolic Differential Equations, 6:127-159, 2009. (submitted version)
19. R. Bürger, S. Diehl and I. Nopens:  A consistent modelling methodology for secondary settling tanks in wastewater treatment. Water Res. 45:2247-2260, 2011. http://dx.doi.org/10.1016/j.watres.2011.01.020
20. E. Torfs, R. Bürger, S. Diehl, S. Farås and I. Nopens: A reliable numerical method for secondary settling modelling. Comm. Appl. Biol. Sci. 77(1), 151-156, 2012.
21. R. Bürger, S. Diehl, S. Farås and I. Nopens: On reliable and unreliable numerical methods for the simulation of secondary settling tanks in wastewater treatment. Computers Chem. Eng. 41:93-105, 2012
22. S. Diehl and S. Farås: Fundamental nonlinearities of the reactor-settler interaction in the activated sludge process. Water Sci. Tech. 66(1):28-35, 2012.
23. S. Diehl and S. Farås: A reduced-order ODE-PDE model for the activated sludge process in wastewater treatment: Classification and stability of steady states. Math. Models Meth. Appl. Sci., 23(3): 369–405, 2013.
24. S. Diehl and S. Farås: Control of  an ideal activated sludge process in wastewater treatment via an ODE-PDE model. J. Process Control. 23:359-381, 2013. (submitted version)
25. R. Bürger and S. Diehl: Convexity-preserving flux identification for scalar conservation laws modelling sedimentation. Inverse Problems. 29(4):045008, 2013.
26. R. Bürger, S. Diehl, S. Farås, I. Nopens and E. Torfs: A consistent modelling methodology for secondary settling tanks: A reliable numerical method. Water Sci. Tech. To appear.

Conference publications

1. S. Diehl, G. Sparr and G. Olsson: Analytical and numerical description of the settling process in the activated sludge operation. In R. Briggs, editor, Instrumentation, Control and Automation of Water and Wastewater Treatment and Transport Systems, pages 471-478. IAWPRC, Pergamon Press, 1990.
2. U. Jeppsson and S. Diehl: Validation of a robust model of continuous sedimentation. Proc. 9th Forum for Applied Biotechnology (FAB), Med. Fac. Landbouww. Univ. Gent, 60/4b, 1995, pp 2403-2414.
3. R. Bürger, S. Diehl, S. Farås and I. Nopens: Simulations of the secondary settling process with consistent numerical methods.WATERMATEX 2011: 8th IWA Symposium on Systems Analysis and Integrated Assessment, San Sebastian, Spain, 2011.
4. S. Diehl and S. Farås: Fundamental nonlinearities of the reactor-settler interaction in the activated sludge process. WATERMATEX 2011: 8th IWA Symposium on Systems Analysis and Integrated Assessment, San Sebastian, Spain, 2011.
5. S. Diehl. Shock-wave behaviour of sedimentation in wastewater treatment: a rich problem. Analysis for Science, Engineering and Beyond. The Tribute Workshop in Honour of Gunnar Sparr held in Lund, May 8-9, 2008. Åström, K.; Persson, L.-E.; Silvestrov, S. D. (Eds.). Springer Proceedings in Mathematics, Springer Berlin Heidelberg.Vol. 6, 175–214, 2012.
6. S. Gedda, C. Andersson, J. Åkesson and S. Diehl: Derivative-free Parameter Optimization of Functional Mock-up Units. Proceedings of the 9th International MODELICA Conference, September 3-5, 2012, Munich, Germany.
   

Submitted manuscripts

1.