Etusivu

Toimitusehdot

Yhteystiedot
Hae:
0 tuotetta ostoskorissa
Ostoskori (0 tuotetta)
Oulun yliopiston väitöskirjat
Terveyttä ruoasta! materiaalit
Oulun yliopiston väitöskirjat
IMPROVING THE ROBUSTNESS WITH MODIFIED BOUNDED HOMOTOPIES AND PROBLEMTAILORED SOLVING PROCEDURES, ACTA UNIVERSITATIS OULUENSIS C Technica 377
ISBN13:
9789514293375
Kieli:
englanti
Kustantaja:
Oulun yliopisto
Oppiaine:
Tekniikka, matematiikka
Painosvuosi:
2010
Sidosasu:
pehmeäkantinen
Sijainti:
Print Tietotalo
Sivumäärä:
176
Tekijät:
MALINEN ILKKA
20.00 €
The aim of this work is to improve the overall robustness in equationoriented chemicalengineering simulation work. Because the performance of locally convergent solving methods isstrongly dependent on a favourable initial guess, bounded homotopy methods were investigatedas a way to enlarge the domain of convergence. Bounded homotopies make it possible to keep thehomotopy path inside a feasible problem domain. Thus the fatal errors possibly caused byunfeasible variable values in thermodynamic subroutines can be avoided. To enable the utilization of a narrow bounding zone, modifications were proposed for boundedhomotopies. The performance of the modifications was studied with simple test problems andseveral types of distillation systems in the MATLAB environment. The findings illustrate that modified bounded homotopies with variables mapping make itpossible to bound the homotopy path strictly to run inside a feasible problem domain. Thehomotopy path can be tracked accurately and flexibly also inside a narrow bounding zone. It was also noticed that by utilizing the concept of bounding the homotopy path with respect tothe homotopy parameter, the possibility of approaching starting point and solution multiplicitiesis increased in cases where the traditional problemindependent homotopy method fails. Theconcept aims to connect separate homotopy path branches thus offering a trackable path with realspace arithmetic. Even though the modified bounded homotopies were found to overcome several challengesoften encountered with traditional problemindependent homotopy continuation methods, alonethey are not enough to guarantee that the solution is approached from an arbitrary starting point.Therefore, problemtailored solving procedures were implemented in the consideration ofcomplex column configurations. Problemtailored solving procedures aim to offer feasibleconsecutive subproblems and thus direct the solving towards the state distribution that fulfilsexact product purity specifications. As a whole, the modified bounded homotopies and problemtailored solving procedures werefound to improve the overall robustness of an equationoriented solving approach. Thus thethreshold for designing and implementing complex process systems such as complex distillationconfigurations for practical use could be lowered.
Takaisin