Business process model and notation

Business Process Model and Notation (BPMN en anglais), c'est-à-dire « modèle de procédé d'affaire et notation », est une méthode de modélisation de processus d'affaires pour décrire les chaînes de valeur et les activités métier d'une organisation sous forme d'une représentation graphique. Elle constitue la norme internationale . BPMN a été développé au départ par la Business Process Management Initiative (BPMI), et est maintenu par l'Object Management Group (OMG) depuis la fusion de ces deux Consortium en juin 2005. La version actuelle de BPMN est la 2.0.2 et date de 2013. Elle est une norme ISO depuis juillet 2013 . But Le but principal de BPMN est de fournir une notation qui soit facilement compréhensible par tous les utilisateurs de l'entreprise, depuis les analystes métier qui créent les ébauches initiales des processus, jusqu'aux développeurs responsables de mettre en place la technologie qui va exécuter les processus applicatifs correspondants, et finalement, jusqu'a

BPMN process generation and optimization for readability in the context of telemedecine

Charline Montial

In business, automated processes can be specified using the BPMN standard, which stands for Business Process Model and Notation. It is presented as flowcharts with standardized graphical elements to show the possible flows and activities of a process. These diagrams can be seen as a graph with logical expressions conditioning their edges. The telemedecine start-up Soignez-moi.ch uses BPMN to describe complex medical forms in a readable way. Soignez-moi.ch offers medical consultations via an online platform. The first step for the patient is to fill a questionnaire about his/her symptoms. In the second step, a doctor accesses to the answers and proceeds to call the patient for the teleconsultation. The complexity of these medical forms comes from the fact that the questions are adapted to the patient answers, which leads to different possible flows. Complex forms from another telemedecine website, Diaana, had to be translated to BPMN to be compatible and used at Soignez-moi.ch. Diaana is a contraction of the words diagnosis and anamnesis. The way these forms are specified is very different from what has been modeled in Soignez-moi.ch: instead of having separated branches, there is a sequential list of questions. In this list, every question is evaluated on its own to see if it is asked or not. The question conditions are Boolean expressions. If a direct translation to BPMN is performed, there is no branching to show the relationships between the questions. The aim of my work is to highlight similarities in the branch conditions to make the diagrams more readable and editable by humans. Doctors and collaborators read the medical BPMN processes and may modify them. It should be a pleasant experience for them to go through the diagrams. They should quickly understand in a visual way if questions are related, and how they are related. The BPMN process readability has been achieved by extracting patterns, showing the implications between the questions to have a readable diagram with meaningful branches. This translation has been applied to 18 questionnaires. Two questionnaires were not improved because they were only composed of one question. One questionnaire was also not improved because all its questions were unconditional, meaning that no relationship between the question conditions could be highlighted. Another questionnaire with conditional questions was not improved because its conditions were unrelated. 14/18 questionnaires have had their readability improved.

2022

Model-based scale-up of a continuously operated consolidated bioprocess based on a microbial consortium for the production of ethanol

David Béat Dempfle

This work demonstrated that consolidated bioprocessing is a promising concept for conversion of lignocellulose to ethanol at industrial scale. CBP offers great cost saving potential, is feasible to be operated continuously and may be scaled up due to extensive knowledge of the process from a chemical engineering point of view.Cost savings of up to 27.5% of the total costs compared to conventional bioethanol production from lignocellulose, as stated by a techno-economic assessment, make continuous CBP the strongest lever to reduce processing costs of lignocellulosic ethanol. A cost sensitivity analysis identified scale and yield as the main cost-pushers from a process point of view, whereas the price level of the plant location has the highest impact on the investment conditions.To prove the feasibility of continuous CBP, and therefore the mentioned cost savings, experiments with a maximum titer of 3.258±0.007 g/L, a productivity of 0.025 g/(Lh) and constant enzyme production over 750h were conducted. Furthermore, the continuous experiments showed that experiments with identical volumetric oxygen transfer rate k_L a, but different oxygen fluxes per membrane area, showed titer differences of ca. 80% (1.83 g/L vs 3.26 g/L) in favor of setups with the large membrane surface. A rigorous process model was developed for continuously operated CBP. 9 species were considered (oxygen, glucose, total concentration Trichoderma reesei, secondary mycelia concentration of T. reesei, enzymes, cellulose, cellobiose, yeast density and ethanol). 8 of these 9 species needed to be modelled spatially resolved to account properly for mass transfer limitations. The fungal biofilm thickness d_f was found to be a critical parameter with an optimum for every membrane configuration. Smaller d_f reduced the fungal biofilm volume and thus, the enzyme production and larger d_f increased the diffusion path length causing shortage in nutrient supply as well as lower enzyme concentrations in the bulk. The enzyme synthesis rate of the secondary mycelia was fitted by reducing it by ca. 40% (0.67 FPU/(mLd) vs 1.152 (FPU/(mL*d) compared to batch models.With the process model as centerpiece, a scale-up framework consisting of the model and a set of non-dimensional parameters was developed to scale CBP from 2.7L laboratory scale to 130L pilot scale. The majority of the non-dimensional parameters could be kept constant during scale-up as requested by the similarity paradigm. Necessary changes were simulated with the model. Again, the fungal biofilm thickness d_f proved to be a relevant parameter for scale-up considerations. In general, the relative loss of biofilm volume is compensated by longer residence times since the residence time has by far the least impact on the process economics.Finally, popular rate-controlled separation techniques were investigated regarding their potential with CBP, since they offer the potential to reduce yeast inhibition, to avoid separation limitations by the azeotrope and they are not bound to the vapor-liquid-equilibrium of highly diluted ethanol-water mixtures. However, most of the mechanisms fail to handle the solids of the fermentation broth. Pervaporation, being the most promising concept for in-situ product removal, would be a cost-saving alternative to distillation for batch operation, but is limited by an unfavorable vapor-liquid equilibrium due to low bulk concentrations during continuous operation.

EPFL2022

Combined optimisation and process integration techniques for the synthesis of fuel cells systems

François Maréchal

A method that combines process modelling and process integration techniques has been developed to tackle the design of complex integrated systems like fuel cell systems. This method uses the equations of the composite curves as constraints to model the ideal heat exchanger network and the corresponding utility system. When combined with the use of process modelling techniques, this method allows to synthesize optimized fuel cell integrated systems with high efficiency and that integrates the technological design constraints.