### Abstract

The effect of model simplification assumptions on the differential index of differential-algebraic equation (DAE) process models is investigated in this paper. A process model is considered as the set of model equations in the form of a DAE system together with a suitable specification forming a zero degree of freedom model. Such a model is described by its equation variable graph. The effect of model simplification assumptions is analyzed by describing them as graph transformations acting on the structure graph of the process model. Efficient incremental graph-theoretic algorithms are proposed to follow the changes in the variable-equation assignments and for analyzing the changes in the differential index during the model simplification phase of the modelling process. The algorithms provide guidelines on how to modify the specification in order to obtain an index 1 model after model simplification. A case study with different transformations is used to demonstrate the operation of the algorithms and to follow the effect of constant and steady-state assumptions on the differential index of a simple process model.

Original language | English |
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Pages (from-to) | 129-137 |

Number of pages | 9 |

Journal | Computers and Chemical Engineering |

Volume | 28 |

Issue number | 1-2 |

DOIs | |

Publication status | Published - Jan 15 2004 |

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### Keywords

- Bipartite matchings
- Differential index
- Directed graphs
- Model transformations
- Process models

### ASJC Scopus subject areas

- Chemical Engineering(all)
- Control and Systems Engineering

### Cite this

**The effect of model simplification assumptions on the differential index of lumped process models.** / Hangos, K.; Szederkényi, G.; Tuza, Z.

Research output: Contribution to journal › Article

}

TY - JOUR

T1 - The effect of model simplification assumptions on the differential index of lumped process models

AU - Hangos, K.

AU - Szederkényi, G.

AU - Tuza, Z.

PY - 2004/1/15

Y1 - 2004/1/15

N2 - The effect of model simplification assumptions on the differential index of differential-algebraic equation (DAE) process models is investigated in this paper. A process model is considered as the set of model equations in the form of a DAE system together with a suitable specification forming a zero degree of freedom model. Such a model is described by its equation variable graph. The effect of model simplification assumptions is analyzed by describing them as graph transformations acting on the structure graph of the process model. Efficient incremental graph-theoretic algorithms are proposed to follow the changes in the variable-equation assignments and for analyzing the changes in the differential index during the model simplification phase of the modelling process. The algorithms provide guidelines on how to modify the specification in order to obtain an index 1 model after model simplification. A case study with different transformations is used to demonstrate the operation of the algorithms and to follow the effect of constant and steady-state assumptions on the differential index of a simple process model.

AB - The effect of model simplification assumptions on the differential index of differential-algebraic equation (DAE) process models is investigated in this paper. A process model is considered as the set of model equations in the form of a DAE system together with a suitable specification forming a zero degree of freedom model. Such a model is described by its equation variable graph. The effect of model simplification assumptions is analyzed by describing them as graph transformations acting on the structure graph of the process model. Efficient incremental graph-theoretic algorithms are proposed to follow the changes in the variable-equation assignments and for analyzing the changes in the differential index during the model simplification phase of the modelling process. The algorithms provide guidelines on how to modify the specification in order to obtain an index 1 model after model simplification. A case study with different transformations is used to demonstrate the operation of the algorithms and to follow the effect of constant and steady-state assumptions on the differential index of a simple process model.

KW - Bipartite matchings

KW - Differential index

KW - Directed graphs

KW - Model transformations

KW - Process models

UR - http://www.scopus.com/inward/record.url?scp=0347360393&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0347360393&partnerID=8YFLogxK

U2 - 10.1016/S0098-1354(03)00166-2

DO - 10.1016/S0098-1354(03)00166-2

M3 - Article

AN - SCOPUS:0347360393

VL - 28

SP - 129

EP - 137

JO - Computers and Chemical Engineering

JF - Computers and Chemical Engineering

SN - 0098-1354

IS - 1-2

ER -