Search Results (489)

As a large-scale flexible structure, the free-vibration characteristics of a horizontal single-axis solar tracking bracket (HSSTB) hold significance for its dynamic optimization design. However, due to material fabrication, construction processes, and harsh field service environments, structural parameters such as the elastic modulus inevitably exhibit uncertainty, leading to discrepancies between actual free-vibration characteristics and design values. This study considers the randomness of the steel elastic modulus and conducts a global sensitivity analysis of a real-life five-column HSSTB. First, the Kriging method is employed to build a surrogate model to describe the natural frequencies of the HSSTB and its stochastic parameters, which enables efficient evaluation of the statistical characteristics of the HSSTB’s natural frequencies. Further, the Sobol indices are utilized to quantify the influence of parameter randomness on the natural frequencies. The results indicate that the mean values of the first five natural frequencies are slightly lower than the design values. The first, fourth, and fifth natural frequencies of the five-column HSSTB are predominantly influenced by the middle three columns, while the second and third natural frequencies are more susceptible to the two edge columns. Full article

Background/Objectives: Sepsis is characterized by a dysregulated host response to infection, where immune-inflammatory and thrombo-inflammation drive organ dysfunction. Early recognition of high-risk patients is essential. In addition, the increasing prevalence of multidrug-resistant (MDR) pathogens complicates therapeutic strategies, as delays in appropriate antimicrobial therapy are strongly associated with poor outcomes. Methods: We conducted a retrospective, single-center cohort study including 120 critically ill patients fulfilling Sepsis-3 criteria. Demographic, clinical, and laboratory data were collected at intensive care unit (ICU) admission, 48 h, and 72 h. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were calculated from complete blood counts. At the same time, the Carmeli score was used as a surrogate for MDR infection risk. Prognostic accuracy was assessed using ROC curve analysis and multivariable logistic regression. Results: Persistently elevated NLR at 72 h and a delayed decline in platelet counts were associated with higher mortality. NLR at 72 h showed good predictive accuracy (AUC = 0.765; 95% CI 0.668–0.863), and the combination of APACHE II and NLR improved prognostic performance (AUC = 0.827). Importantly, the Carmeli score, reflecting MDR infection risk, was an independent predictor of outcome, linking antimicrobial resistance risk with sepsis prognosis. Conclusions: Dynamic immune-inflammatory biomarkers (NLR, platelets), when integrated with MDR risk assessment through the Carmeli score, provide a simple and cost-effective strategy for early prognostic stratification in sepsis. This combined approach may help facilitate early therapeutic decisions and patient care triage. Full article

Accurate prediction of urban wind flow is essential for urban planning and environmental assessment. Classical computational fluid dynamics (CFD) methods are computationally expensive, while machine learning approaches often lack explainability and generalizability. To address the limitations of both approaches, we propose Diff-KNN, a hybrid method that combines Coarse-Scale CFD simulations with a K-Nearest Neighbors (KNN) model trained on the residuals between coarse- and fine-scale CFD results. Diff-KNN reduces velocity prediction errors by up to 83.5% compared to Pure-KNN and 56.6% compared to coarse CFD alone. Tested on the AIJE urban dataset, Diff-KNN effectively corrects flow inaccuracies near buildings and within narrow street canyons, where traditional methods struggle. This study demonstrates how residual learning can bridge physics-based and data-driven modeling for accurate and interpretable fine-scale urban wind prediction. Full article

To address the challenge of time-varying reliability assessment for double-span rotor systems under misalignment faults and load-sharing conditions, a time-varying reliability modeling method based on neural networks and reliability velocity mapping is proposed in this paper. By establishing a system dynamics model coupled with misalignment fault, a feedforward neural network surrogate model is constructed to efficiently predict stochastic stress responses, overcoming the limitations of high computational cost and difficulty in probabilistic analysis inherent in traditional finite element methods. Furthermore, by introducing the concept of reliability velocity, an intelligent mapping from independent systems to dependent systems is established, significantly enhancing the assessment accuracy of system time-varying reliability under small-sample conditions. Case study validation demonstrates that the proposed method can accurately capture the system degradation behavior under load-sharing and failure dependency mechanisms, providing a theoretical foundation for reliability analysis and intelligent operation and maintenance of rotor systems. Full article

Mutations in IDH1/2 are frequent in Acute Myeloid Leukemia (AML), defining a molecularly distinct subgroup with therapeutic implications due to the availability of specific inhibitors. Accurate monitoring of treatment response is crucial and Droplet Digital PCR (ddPCR) offers a sensitive approach for quantifying mutational burden in IDH-mutated AML. This study aimed to optimize and validate ddPCR assays specific for IDH1 R132 and IDH2 R172/R140 mutations for future use in Minimal Residual Disease (MRD) monitoring. Four ddPCR assays were set to evaluate the trend of IDH1/2 mutations in 191 diagnostic and follow-up samples. Each validation procedure included determining the limit of blank (LOB) and limit of detection (LOD) using titration series. Moreover, in AML harboring both IDH and NPM1 mutations, we performed generalized estimating equations (GEE) to assess the association between IDH fractional abundance and NPM1 RQ-Ratio across time points. Four IDH1/2 ddPCR assays were validated, demonstrating high sensitivity with limits of detection of 0.07% for IDH1 R132H, 0.1% for IDH2 R140Q and R172K, and 0.2% for IDH1 R132C. The method also exhibited excellent intra-run reproducibility, providing consistent results for patient follow-up. Comparison of IDH and NPM1 trends during follow-up revealed a statistically significant positive correlation, both in raw (β = 0.079, p = 0.001) and ranked data (β = 0.99, p = 0.004), suggesting a co-dynamic pattern potentially useful for surrogate monitoring. While our study cannot yet define the clinical role of IDH mutation assessment by ddPCR due to the lack of comparative follow-up studies, it establishes a solid methodological foundation for standardizing minimal residual disease evaluation via ddPCR, paving the way for future prospective validation. Full article

Financial sustainability in higher education is increasingly fragile due to policy shifts, rising costs, and funding volatility. Legacy early-warning systems based on static thresholds or rules struggle to adapt to these dynamics and often overlook fairness and interpretability—two essentials in public-sector governance. We propose a university financial risk early-warning framework that couples a causal-attention Transformer with Multi-Objective Bayesian Optimization (MBO). The optimizer searches a constrained Pareto frontier to jointly improve predictive accuracy (AUC↑), fairness (demographic parity gap, DP_Gap↓), and computational efficiency (time↓). A sparse kernel surrogate (SKO) accelerates convergence in high-dimensional tuning; a dual-head output (risk probability and health score) and SHAP-based attribution enhance transparency and regulatory alignment. On multi-year, multi-institution data, the approach surpasses mainstream baselines in AUC, reduces DP_Gap, and yields expert-consistent explanations. Methodologically, the design aligns with LLM-style time-series forecasting by exploiting causal masking and long-range dependencies while providing governance-oriented explainability. The framework delivers earlier, data-driven signals of financial stress, supporting proactive resource allocation, funding restructuring, and long-term planning in higher education finance. Full article

Compaction quality control in earthworks and pavements still relies mainly on density-based acceptance referenced to laboratory Proctor tests, which are costly, time-consuming, and spatially sparse. Lightweight dynamic cone penetrometer (LDCP) provides rapid indices, such as $q_{d0}$ and $q_{d1}$, yet acceptance thresholds commonly depend on ad hoc, site-specific calibrations. This study develops and validates a supervised machine learning framework that estimates $q_{d0}$, $q_{d1}$, and $Z_c$ directly from readily available soil descriptors (gradation, plasticity/activity, moisture/state variables, and GTR class) using a multi-campaign dataset of $n=360$ observations. While the framework does not remove the need for the standard soil characterization performed during design (e.g., W, ${\gamma }_{d,\mathrm{field}}$, and $R{C}_{\mathrm{SPC}}$), it reduces reliance on additional LDCP calibration campaigns to obtain device-specific reference curves. Models compared under a unified pipeline include regularized linear baselines, support vector regression, Random Forest, XGBoost, and a compact multilayer perceptron (MLP). The evaluation used a fixed 80/20 train–test split with 5-fold cross-validation on the training set and multiple error metrics ($R^2$, RMSE, MAE, and MAPE). Interpretability combined SHAP with permutation importance, 1D partial dependence (PDP), and accumulated local effects (ALE); calibration diagnostics and split-conformal prediction intervals connected the predictions to QA/QC decisions. A naïve GTR-average baseline was added for reference. Computation was lightweight. On the test set, the MLP attained the best accuracy for $q_{d1}$ ($R^2=0.794$, RMSE $=5.866$), with XGBoost close behind ($R^2=0.773$, RMSE $=6.155$). Paired bootstrap contrasts with Holm correction indicated that the MLP–XGBoost difference was not statistically significant. Explanations consistently highlighted density- and moisture-related variables (${\gamma }_{d,\mathrm{field}}$, $R{C}_{\mathrm{SPC}}$, and W) as dominant, with gradation/plasticity contributing second-order adjustments; these attributions are model-based and associational rather than causal. The results support interpretable, computationally efficient surrogates of LDCP indices that can complement density-based acceptance and enable risk-aware QA/QC via conformal prediction intervals. Full article

Enhancing productivity while reducing environmental impact presents a major engineering challenge in sustainable dairy farming. This study proposes an engineering-oriented explainable machine learning and digital twin framework for multi-objective optimisation of milk yield and nitrogen-related emissions. Using the CowNflow dataset, which integrates individual-level nitrogen balance, feeding, and production data collected under controlled experimental conditions, the framework combines data analytics, feature selection, predictive modelling, and SHAP-based explainability to support decision-making in dairy production. The stacking ensemble model achieved the best predictive performance ($R^2$ = 0.85 for milk yield and $R^2$ = 0.794 for milk urea), providing reliable surrogates for downstream optimisation. Predicted milk urea values were further transformed using empirical equations to estimate urinary urea nitrogen (UUN) and ammonia (NH₃) emissions, offering an indirect yet practical approach to assess environmental sustainability. Furthermore, the predictive models are integrated into a digital twin platform that provides a dynamic, real-time simulation environment for scenario testing, continuous optimisation, and data-driven decision support, effectively bridging data analytics with sustainable dairy system management. This research demonstrates how explainable AI, machine learning, and digital twin engineering can jointly drive sustainable dairy production, offering actionable insights for improving productivity while minimising environmental impact. Full article

Accurate and efficient CFD simulations are essential for a wide range of engineering and scientific applications, from resilient structural design to environmental analysis. Traditional methods such as RANS simulations often face challenges in capturing complex flow phenomena like separation, while high-fidelity approaches including Large Eddy Simulations and Direct Numerical Simulations demand significant computational resources, thereby limiting their practical applicability. This paper provides an in-depth synthesis of recent advancements in integrating artificial intelligence and machine learning techniques with CFD to enhance simulation accuracy, computational efficiency, and modeling capabilities, including data-driven surrogate models, physics-informed methods, and ML-assisted numerical solvers. This integration marks a crucial paradigm shift, transcending incremental improvements to fundamentally redefine the possibilities of fluid dynamics research and engineering design. Key themes discussed include data-driven surrogate models, physics-informed methods, ML-assisted numerical solvers, inverse design, and advanced turbulence modeling. Practical applications, such as wind load design for solar panels and deep learning approaches for eddy viscosity prediction in bluff body flows, illustrate the substantial impact of ML integration. The findings demonstrate that ML techniques can accelerate simulations by up to 10,000 times in certain cases while maintaining or improving the accuracy, particularly in challenging flow regimes. For instance, models employing learned interpolation can achieve 40- to 80-fold computational speedups while matching the accuracy of baseline solvers with a resolution 8 to 10 times finer. Other approaches, like Fourier Neural Operators, can achieve inference times three orders of magnitude faster than conventional PDE solvers for the Navier–Stokes equations. Such advancements not only accelerate critical engineering workflows but also open unprecedented avenues for scientific discovery in complex, nonlinear systems that were previously intractable with traditional computational methods. Furthermore, ML enables unprecedented advances in turbulence modeling, improving predictions within complex separated flow zones. This integration is reshaping fluid mechanics, offering pathways toward more reliable, efficient, and resilient engineering solutions necessary for addressing contemporary challenges. Full article

The rapid proliferation of electric vehicles (EVs) demands lightweight yet efficient battery thermal management systems (BTMS). The fin-embedded phase-change material energy storage tube (PCM-EST) offers significant potential due to its high thermal energy density and passive operation, but conventional designs face a critical trade-off: enhancing heat transfer typically increases mass, conflicting with EV lightweight requirements. To resolve this conflict, this study proposes a multi-objective surrogate optimization framework integrating computational fluid dynamics (CFD) and Kriging modeling. Fin geometric parameters—number, height, and tube length—were rigorously analyzed via ANSYS (2020 R1) Fluent simulations to quantify their coupled effects on PCM melting/solidification dynamics and structural mass. The results reveal that fin configurations dominate both thermal behavior and weight. An enhanced multi-objective particle swarm optimization (MOPSO) algorithm was then deployed to simultaneously maximize heat transfer and minimize mass, generating a Pareto-optimal solution. The optimized design achieves 8.7% enhancement in heat exchange capability and 0.732 kg mass reduction—outperforming conventional single-parameter designs by 37% in weight savings. This work establishes a systematic methodology for synergistic thermal-structural optimization, advancing high-performance BTMS for sustainable EVs. Full article

Floods are among the most destructive natural hazards, with damages expected to intensify under climate change and socio-economic pressures. Effective reservoir operation remains a critical yet challenging strategy for mitigating downstream impacts, as operators must navigate nonlinear system dynamics, uncertain inflow forecasts, and trade-offs between competing objectives. This study proposes a novel end-to-end data-driven framework that integrates process-based hydraulic simulations, a Transformer-based surrogate model for flood damage prediction, and reinforcement learning (RL) for reservoir gate operation optimization. The framework is demonstrated using the Coralville Reservoir (Iowa, USA) and two major historical flood events (2008 and 2013). Hydraulic and impact simulations with HEC-RAS and HEC-FIA were used to generate training data, enabling the development of a Transformer model that accurately predicts time-varying flood damages. This surrogate is coupled with a Transformer-enhanced Deep Q-Network (DQN) to derive adaptive gate operation strategies. Results show that the RL-derived optimal policy reduces both peak and time-integrated damages compared to expert and zero-opening benchmarks, while maintaining smooth and feasible operations. Comparative analysis with a genetic algorithm (GA) highlights the robustness of the RL framework, particularly its ability to generalize across uncertain inflows and varying initial storage conditions. Importantly, the adaptive RL policy trained on perturbed synthetic inflows transferred effectively to the hydrologically distinct 2013 event, and fine-tuning achieved near-identical performance to the event-specific optimal policy. These findings highlight the capability of the proposed framework to provide adaptive, transferable, and computationally efficient tools for flood-resilient reservoir operation. Full article

Prediction of the maneuvering performance of autonomous underwater vehicles equipped with pump–jet propulsion remains computationally intensive when relying solely on high-fidelity computational fluid dynamics. To overcome this limitation, a surrogate maneuvering model is developed to achieve comparable accuracy with drastically reduced computational cost. The model is constructed from numerical results obtained using unsteady Reynolds-averaged Navier–Stokes equations with the k–ω shear stress transport turbulence model, and formulated through a Taylor-expansion-based framework. The propulsion and rudder modules are refined to enhance physical representation and efficiency: a conventional open-water-based formulation is adopted to embed the pump–jet propulsive model, incorporating axial flow velocities near the duct inlet for improved thrust prediction; meanwhile, the rudder force model minimizes the number of captive simulations by employing a kinematic approach that compensates for limited datasets. The surrogate model is applied to free-running simulations and validated against high-fidelity computational results. The findings confirm that the proposed framework reproduces the dominant trends of kinematic responses, forces, and moments with high consistency, providing a practical and time-efficient alternative for maneuvering prediction of underwater vehicles equipped with pump–jet propulsion systems. Full article

This review surveys recent progress in hybrid artificial intelligence (AI) approaches for gas turbine intelligent digital twins, with an emphasis on models that integrate physics-based simulations and machine learning. The main contribution is the introduction of a structured classification of hybrid AI methods tailored to gas turbine applications, the development of a novel comparative maturity framework, and the proposal of a layered roadmap for integration. The classification organizes hybrid AI approaches into four categories: (1) artificial neural network (ANN)-augmented thermodynamic models, (2) physics-integrated operational architectures, (3) physics-constrained neural networks (PcNNs) with computational fluid dynamics (CFD) surrogates, and (4) generative and model discovery approaches. The maturity framework evaluates these categories across five criteria: data dependency, interpretability, deployment complexity, workflow integration, and real-time capability. Industrial case studies—including General Electric (GE) Vernova’s SmartSignal, Siemens’ Autonomous Turbine Operation and Maintenance (ATOM), and the Electric Power Research Institute (EPRI) turbine digital twin—illustrate applications in real-time diagnostics, predictive maintenance, and performance optimization. Together, the classification and maturity framework provide the means for systematic assessment of hybrid AI methods in gas turbine intelligent digital twins. The review concludes by identifying key challenges and outlining a roadmap for the future development of scalable, interpretable, and operationally robust intelligent digital twins for gas turbines. Full article

To advance global sustainability and meet climate targets, the development of reliable renewable energy infrastructure is paramount. Offshore wind energy is a key factor in achieving this goal, and ensuring its operational efficiency requires a deep understanding of the sources of uncertainty faced by offshore wind turbines (OWTs). This study proposes and implements an integrated framework for sensitivity analysis (SA) to investigate the key sources of uncertainty influencing the dynamic response of an OWT. This framework is based on the XGBoost surrogate model and Sobol’s method, aiming to efficiently and accurately quantify the impact of various uncertain parameters. A key methodological novelty lies in the integrated use of Sobol’s method and SHapley Additive exPlanations (SHAP), which provides a unique cross-validating mechanism for the sensitivity results. This study demonstrates the strongly condition-dependent nature of the OWT’s sensitivity characteristics by analyzing design load cases. The results indicate that wind speed is the dominant factor influencing the structural response under normal operating conditions. In contrast, under extreme shutdown conditions, the response of the OWT is primarily governed by the physical and material properties of the structure. In addition, the high consistency between the results of SHAP technology and the SA results obtained by Sobol’s method confirms the reliability of the proposed framework. The identified key sources of uncertainty provide direct practical insights for design optimization and reliability assessment of OWTs. Full article

With the growing complexity of high-dimensional imbalanced datasets in critical fields such as medical diagnosis and bioinformatics, feature selection has become essential to reduce computational costs, alleviate model bias, and improve classification performance. DS-IHBO, a dynamic surrogate-assisted feature selection algorithm integrating relevance-based redundant feature filtering and an improved hybrid breeding algorithm, is presented in this paper. Departing from traditional surrogate-assisted approaches that use static approximations, DS-IHBO employs a dynamic surrogate switching mechanism capable of adapting to diverse data distributions and imbalance ratios through multiple surrogate units built via clustering. It enhances the hybrid breeding algorithm with asymmetric stratified population initialization, adaptive differential operators, and t-distribution mutation strategies to strengthen its global exploration and convergence accuracy. Tests on 12 real-world imbalanced datasets (4–98% imbalance) show that DS-IHBO achieves a 3.48% improvement in accuracy, a 4.80% improvement in F1 score, and an 83.85% reduction in computational time compared with leading methods. These results demonstrate its effectiveness for high-dimensional imbalanced feature selection and strong potential for real-world applications. Full article