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    Item type:Publication, Access status: with files ,
    CO₂-driven pH control in the enzymatic hydrolysis of urea: stochastic model predictive control under uncertainty
    (American Chemical Society (ACS), 2026-07-09) ; ; ;
    Enzymatic urea hydrolysis is a mild route to ammonia production, but urease activity is strongly pH dependent. In buffer-free operation, pH can drift substantially because ammonia and inorganic carbon rapidly repartition through acid−base equilibria. Detailed process-modeling background, experimental protocol, and parameter identification context are reported in a companion manuscript by Dittmer, K. R. (2026). Here, in contrast, we develop an uncertainty-aware modeling and control framework for CO₂-driven pH regulation during urease-catalyzed urea hydrolysis. A control-oriented mechanistic model couples pHdependent urease kinetics with substrate and product inhibition, fast speciation with electroneutrality-based pH computation, and gas−liquid mass transfer of NH3 and CO₂ in a headspace. Parametric uncertainty in kinetic and transfer parameters is propagated using nonintrusive polynomial chaos expansion. Building on these predictions, we propose a stochastic model predictive control (SMPC) scheme that tracks a pH reference under input constraints while enforcing chance constraints on pH safety bounds. Simulations demonstrate uncertainty-aware pH regulation without buffer salts under the considered parametric uncertainty scenarios, providing a foundation for automated operation of enzymatic reactors under uncertainty.
    Publicationtype: Journal Article
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    Item type:Publication,
    Uncertainty propagation under residual disturbances: a smart-home case study
    (2026-05-15) ;
    Reinhardt, Dirk
    ;
    Gros, Sebastien
    ;
    This paper presents a data-driven framework for uncertainty propagation under unmeasured or statistically unmodeled (unstructured) disturbances. We consider residual disturbances, which consolidate all unstructured disturbances into a single quantity that can be estimated from data. Under mild assumptions, the resulting stochastic predictor is causal and distributionally consistent, enabling efficient uncertainty quantification through polynomial chaos expansions and higher-order Chebyshev inequalities. The proposed method is validated using experimental data from a smart home in Norway.
    Publicationtype: Preprint
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