Modelling

Background: A patient’s lung condition can be estimated using mechanical ventilation waveform data. These procedures are often labour-intensive and error-prone, especially during large-scale health crises, leading to infrequent executions. Automated diagnostic techniques in healthcare are currently limited by the lack of large, labelled datasets required for effective machine learning applications. Analytical modelling of the mechanical ventilator-patient (MV-P) system is complex, and existing models fail to fully integrate adjustable parameters for patient, ventilation, and disease conditions. Methods: This article presents an expanded system model developed in MATLAB^® Simulink^®. The model accommodates adjustments to anthropometric parameters, ventilator settings for the three most common modes in ICU sedation, and disease progression simulations. Other uniquely combined aspects include the ability to perform an end-inspiratory hold manoeuvre and per-breath optimisation of PI control parameters. Results: The system has been validated against clinical techniques, compared to real-world data, and verified with accuracy within 3% and average normalised standard deviation of 3.4% for all adjustable parameters. Conclusions: Based on this model, which introduces high-fidelity disease progression modelling, a fully labelled synthetic dataset of nearly 2M breaths over a range of health conditions was generated. This addresses the critical shortage of labelled data needed for developing early proof-of-concept, resource-efficient diagnostic tools for automatically estimating lung conditions.

Resistance against water penetration is one of the key indicators of concrete durability in humid and pressurized environments. An intelligent model based on the XGBoost machine-learning algorithm was developed to predict the water penetration depth, using 1512 independent experimental measurements. The influential variables included water pressure, pressure duration, thermal cycles, fiber content, curing, and compressive strength. The investigated concrete specimens and field-tested structures in this study were exposed to arid and hot climatic conditions, and the proposed model was developed within this environmental context. To accurately simulate the water transport behavior, a cylindrical-chamber test was employed, enabling non-destructive and in-situ evaluation of structures. Correlation analysis revealed that compressive strength had the strongest negative influence (r = −0.598), while free curing exhibited the strongest positive influence (r = +0.654) on penetration depth. After hyperparameter optimization, the XGBoost model achieved the best performance (R² = 0.956, RMSE = 1.08 mm, MAE = 0.81 mm). Feature importance analysis indicated that penetration volume, pressure, and curing were the most significant predictors. According to the partial dependence analysis, both pressure and duration exhibited an approximately linear increase in penetration depth, while a W/C ratio below 0.45 and curing markedly reduced permeability. Microstructural interpretation using MIP, XRD, and SEM tests supported the physical interpretation of the trends identified by the machine-learning model. The results demonstrate that machine-learning-models can serve as fast and accurate tools for assessing durability and predicting permeability under severe environmental conditions. Finally, the permeability of several real structures was evaluated using the machine-learning approach, showing excellent prediction accuracy.

Parametrization of photovoltaic (PV) modules makes an important foundation for monitoring and fault diagnosis. This work focus on the sensitivity of parameters for the single-diode model (SDM), which fills the gap in existing research. The sensitivity analysis in this work provides a fundamentally new perspective on understanding parameter robustness as well as the prior knowledge for the parameter identification method. Based on insights into the sensitivity analysis, a novel parameter identification method is proposed, which combines analytical expressions with the grid search algorithm. The proposed method reduces the relative error of the extracted parameters in the simulated dataset, and the quantitative improvement of the reverse saturation current is significant (12.6% average reduction). This method achieves the state-of-the-art overall performance in the measured dataset, and the Friedman test confirms that this improvement is statistically significant (p < 0.05). The transition capability of the proposed method is excellent under varying operating conditions, which implies that it has the potential to be applied to the intelligent operation and maintenance of photovoltaic systems.