Publications by Julien Léo Billeter

Sequential model identification of reaction systems-The missing path between the incremental and simultaneous approaches

Dominique Bonvin, Julien Léo Billeter, Sriniketh Srinivasan

Modeling chemical reaction systems is an important but complex task. The identified kinetic model must be able to explain all the underlying rate processes such as chemical reactions and heat and mass transfers. Traditionally, the modeling task is carried ...

2019

Incremental Parameter Estimation under Rank-Deficient Measurement Conditions

Dominique Bonvin, Julien Léo Billeter

The computation and modeling of extents has been proposed to handle the complexity of large-scale model identification tasks. Unfortunately, the existing extent-based framework only applies when certain conditions apply. Most typically, it is required that ...

2019

Maximum-likelihood estimation of kinetic parameters via the extent-based incremental approach

Dominique Bonvin, Julien Léo Billeter, Diogo Filipe Mateus Rodrigues

For lumped homogeneous reaction systems, this paper presents a kinetic model identification scheme that provides maximum-likelihood parameter estimates and guarantees convergence to global optimality. The use of the extent-based incremental approach allows ...

PERGAMON-ELSEVIER SCIENCE LTD2019

On decoupling rate processes in chemical reaction systems - Methods and applications

Michael Amrhein, Dominique Bonvin, Julien Léo Billeter, Diogo Filipe Mateus Rodrigues

Models of chemical reaction systems can be complex as they need to include information regarding the reactions and the mass and heat transfers. The commonly used state variables, namely, concentrations and temperatures, express the interplay between many p ...

2018

Fast Estimation of Plant Steady State for Imperfectly Known Dynamic Systems, with Application to Real-Time Optimization

Michael Amrhein, Dominique Bonvin, Julien Léo Billeter, Diogo Filipe Mateus Rodrigues

2018

Global Identification of Kinetic Parameters via the Extent-based Incremental Approach

Dominique Bonvin, Julien Léo Billeter, Diogo Filipe Mateus Rodrigues

The identification of reaction kinetics represents the main challenge in building models for reaction systems. The identification task can be performed via either simultaneous model identification (SMI) or incremental model identification (IMI), the latter ...

2017

Concept and Applications of Extents in Chemical Reaction Systems

Michael Amrhein, Dominique Bonvin, Julien Léo Billeter, Sriniketh Srinivasan, Diogo Filipe Mateus Rodrigues

Models of chemical reaction systems can be quite complex as they typically include information regarding the reactions, the various transfers of heat and mass, as well as the effects of the inlet and outlet flows. It is well known that a linear transformat ...

2017

Extent Computation under Rank-deficient Conditions

Dominique Bonvin, Julien Léo Billeter

The identification of kinetic models can be simplified via the computation of extents of reaction on the basis of invariants such as stoichiometric balances. With extents, one can identify the structure and the parameters of reaction rates individually, wh ...

2017

Optimal Control Laws for Batch and Semi-batch Reactors Using the Concept of Extents

Dominique Bonvin, Julien Léo Billeter, Diogo Filipe Mateus Rodrigues

2017

Generalization of the Concept of Extents to Distributed Reaction Systems

Dominique Bonvin, Julien Léo Billeter, Diogo Filipe Mateus Rodrigues

In the chemical industry, a large class of processes involving reactions can be described by partial differential equations that depend on time and on one or more spatial coordinates. Examples of such distributed reaction systems are tubular reactors and r ...

Elsevier2017

Generalized Incremental Model Identification for Chemical Reaction Systems

Dominique Bonvin, Julien Léo Billeter, Adrien Oulevey, Diogo Filipe Mateus Rodrigues

Identification of kinetic models and estimation of kinetic parameters in chemical reaction systems can be done using Incremental Model Identification (IMI). By using IMI, it is possible to separate the effect of the different reactions and thus investigate ...

2017

Shape constrained splines as transparent black-box models for bioprocess modeling

Dominique Bonvin, Julien Léo Billeter, Sriniketh Srinivasan

Empirical model identification for biological systems is a challenging task due to the combined effects of complex interactions, nonlinear effects, and lack of specific measurements. In this context, several researchers have provided tools for experimental ...

Elsevier2017

Semi-analytical Solutions for Tubular Chemical Reactors

Dominique Bonvin, Julien Léo Billeter, Diogo Filipe Mateus Rodrigues

The one-dimensional tubular reactor model with advection and possibly axial diffusion is the classical model of distributed chemical reaction systems. This system is described by partial differential equations that depend on the time t and the spati ...

Elsevier2017

Reaction extents: A Divide-and-Conquer Approach for Kinetic Model Identification

Dominique Bonvin, Julien Léo Billeter

Obtaining reliable wastewater treatment process models is critical for the application of model-based design, operation, and automation. For example, Masic et al. (2014) explored the use of an observer designed for nonlinear processes to estimate nitrite i ...

2017

Identification of Biokinetic Models Using the Concept of Extents

Dominique Bonvin, Julien Léo Billeter, Sriniketh Srinivasan

The development of a wide array of process technologies to enable the shift from conventional biological wastewater treatment processes to resource recovery systems is matched by an increasing demand for predictive capabilities. Mathematical models are exc ...

Amer Chemical Soc2017

Data Reconciliation for Reaction Systems Using Extents and Shape Constraints

Dominique Bonvin, Julien Léo Billeter, Sriniketh Srinivasan

Concentrations measured during the course of reactions are typically corrupted by random noise. Data reconciliation techniques improve the accuracy of measurements by using redundancies in the material and energy balances expressed as relationships between ...

Elsevier2017

Incremental Kinetic Modeling of Spectroscopic Data using a Reduced Calibration Model

Dominique Bonvin, Julien Léo Billeter

The identification of kinetic models is an important step for the monitoring, control and optimization of chemical processes. Kinetic models are often based on first principles that describe the evolution of concentrations by means of conservation and cons ...

2017

ALS Scheme using Extent-based Constraints for the Analysis of Chemical Reaction Systems

Michael Amrhein, Dominique Bonvin, Julien Léo Billeter

Multivariate curve resolution via alternating least squares (ALS) is used to resolve the concentration profiles C and the pure component spectra E of S species from the multivariate absorbance data A, assuming the bilinear model ...

2016

Fast Estimation of Plant Steady State, with Application to Static RTO

Michael Amrhein, Dominique Bonvin, Julien Léo Billeter, Diogo Filipe Mateus Rodrigues

Experimental assessment or prediction of plant steady state is important for many applications in the area of modeling and operation of continuous processes. For example, the iterative implementation of static real-time optimization requires reaching stead ...

2016

On the Use of Shape-Constrained Splines for Biokinetic Process Modelling

Dominique Bonvin, Julien Léo Billeter, Sriniketh Srinivasan

Identification of mathematical models is an important task for the design and the optimization of biokinetic processes. Monod or Tessier growth-rate models are often chosen by default, although these models are not able to represent the dynamics of all bac ...

Elsevier Science Bv2016