Methodology gaps in Engineering

Representative open questions

Showing 30 of 123 — one per source paper, highest-quality first.

• Basalt powder as a sustainable precursor in alkali‑activated materials: a critical review of performance, mechanisms, and durability (2026) · doi

  The alkali fusion pre-treatment of basalt powder at 450–750 °C increased reaction degree from 8% to 38% and 7-day strength from 2.4 to 12.1 MPa, but the optimal temperature, NaOH ratio, and heating duration have not been systematically optimized. Additionally, the scalability and economic feasibility of alkali fusion as an industrial pre-treatment method for BP in alkali-activated materials requires investigation.

• Sophisticated control design for direct drive permanent magnet synchronous generator-based wind turbines under voltage sags (2026) · doi

  The paper acknowledges that dedicated devices and strategies are recommended for longer voltage sag events but does not specify what these strategies are or how they should be integrated with the proposed control design methodology for PMSG-based wind turbines operating under sustained low-voltage conditions.

• Experimental evaluation of bond performance between substrate and overlay concrete using bonding agents and mechanical connectors (2026) · doi

  The study identifies that SBR-200 bonding agent efficacy under pure shear conditions is dependent upon application thickness and interaction with textured substrate profile, but no systematic investigation of optimal SBR-200 application thickness ranges or substrate surface roughness profiles is provided to guide practical repair implementation.

• Metal repair using hybrid additive manufacturing process: A comparative study of interfacial surface roughness for improved mechanical strength (2026) · doi

  The FE model is limited to interpreting mechanical responses of repaired components and cannot identify optimal surface roughness values for hybrid additive manufacturing repair. Future work must develop physics-based microstructural models that incorporate interfacial roughness parameters to determine the specific roughness range (between the tested 8.76 μm and 91.57 μm) that maximizes bonding strength.

• Preg-Robbing in Refractory Gold Ores: A Critical Review of Mineralogical Controls, Pretreatment Strategies and Flowsheet Selection (2026) · doi

  The interaction effects between pretreatment methods (roasting, BIOX, POX) and alternative lixiviants (thiosulfate, glycine-based, halide systems) have not been systematically quantified; specific kinetic and thermodynamic data comparing recovery rates and preg-robbing losses across hybrid flowsheet combinations are needed.

• Advancement in fusion welded aluminium alloy joints by friction stir processing technique: a critical review (2026) · doi

  The integration of FSP with external stimuli such as ultrasonic vibration, electromagnetic assistance, or controlled thermal environments (cryogenic or localized heating) has not been systematically explored to determine optimal coupling parameters, energy efficiency, and the resulting microstructural refinement mechanisms in fusion-welded aluminium alloy joints.

• Harnessing Surface Instabilities for Functional Materials: Mechanics, Morphology, and Emerging Applications (2026) · doi

  Dynamic reversible evolution of wrinkles on floating polymer films under magnetic control has been demonstrated, but the quantitative relationship between magnetic field strength, frequency, and wrinkle reversibility cycles before permanent deformation or material fatigue remains uncharacterized.

• Advances of artificial intelligence applications to low-carbon metallurgy of iron and steel (2026) · doi

  The burn-through point prediction in iron ore sintering has been modeled using fuzzy time series approaches, but integration of these soft-sensing models with weighted kernel just-in-time learning for real-time adaptive prediction across varying ore compositions and operating conditions needs systematic investigation.

• Revisiting the Modification Strategies of Alloy-Base Anode for Solid-State Lithium-Ion Batteries Through Deconstructing Anode-Interface-Solid Electrolyte (2026) · doi

  The PVDF-PEO composite electrolyte system's ionic conductivity improvement mechanism through ether oxygen coordination with lithium ions has not been systematically characterized across different PEO:PVDF ratios and molecular weight combinations. Quantitative structure-property relationships for optimizing the synergistic effect between PVDF mechanical properties and PEO ionic conductivity in solid-state lithium-ion batteries require systematic investigation.

• Bayesian optimization for uncertainty-aware prediction of rainfall-induced deformation in embankment dams (2026) · doi

  The multiplicative uncertainty-calibrated score (UCS) formulation achieves near-nominal coverage but yields comparatively inferior final UCS values relative to weighted formulations (e.g., 0.7EC + 0.3CRPS). Future work should investigate why this trade-off exists and whether hybrid or adaptive UCS formulations can simultaneously optimize convergence speed and asymptotic uncertainty sharpness in Bayesian optimization of prediction intervals for dam deformation.

• Design Optimization of an Additively Manufactured Passive Vibration Isolator for an Inertial Measurement Unit for Enhanced Measurement Performance (2026) · doi

  The nonlinear finite element analysis assumes isotropic material properties for PLA and aluminum components; however, additive manufacturing introduces anisotropy and directional mechanical property variations depending on print orientation and infill parameters (Table 6 lists infill parameters but analysis does not account for print direction effects).

• Physics-Informed Symbolic Regression Ensemble (PISRE) for surface roughness prediction in Ti-6Al-4V dry turning (2026) · doi

  While hyperparameter sensitivity analysis (Section 4.8.7) covers Ridge regularisation α and neighbourhood size k, the sensitivity of the four-branch symbolic regression structure itself (Branches A–D physics-derived features) to variations in feature engineering or constraint parameterization has not been systematically explored.

• Evaluating interior lighting as an indoor environmental quality component using virtual reality (2026) · doi

  Multi-sensory integration in VR lighting simulations remains underdeveloped; while visual realism in photometric rendering is achieved, thermal feedback, olfactory simulation, and spatial acoustics integration with lighting conditions have not been systematically evaluated for their combined effects on occupant responses.

• Wind Tunnel Testing for Wind Energy: A State-of-the-Art Review (2026) · doi

  Computational domain size significantly affects 2D CFD predictions in separated flow conditions for wind turbine airfoils. Current studies show that computational domains greater than 0.5 chord width improve predictions for both RANS and DES simulations, but systematic investigation of optimal domain sizing across different Reynolds numbers and angle-of-attack ranges for wind turbine airfoils is lacking.

• Multifunctional zinc-ion capacitors for energy storage (2026) · doi

  For integrated electrochemical-storage systems like electrochromic zinc-ion capacitors (ECZ-ICs), high mass loading negatively affects electrochemical capacitor performance. The trade-off between electrochemical performance and energy storage performance in these multifunctional systems requires quantitative investigation to establish optimal loading thresholds.

• Functional nanocomposites for energy storage: chemistry and new horizons (2020) · doi

  The random distribution of air voids in nanocomposites fabricated above 50% volume fraction significantly reduces dielectric breakdown strength, but no systematic method has been developed to control or predict void distribution patterns in polymer-ceramic nanocomposites during processing.

• Smart Gloves for Sign Language to Text Conversion Translation Using Arduino Mega With 8 Flex Sensors (2026) · doi

  The smart glove system currently addresses sensor placement inconsistencies through manual calibration, but no systematic methodology is provided for standardizing flex sensor positioning across different hand sizes or morphologies. A calibration protocol that accounts for anatomical variation in finger length and joint positioning should be developed to ensure consistent gesture recognition accuracy.

• Automatic Car Parking System by using ESP 32 (2026) · doi

  The I2C LCD displays slot availability in real-time, but the paper does not specify the communication protocol robustness, error handling for I2C bus conflicts, or performance degradation when multiple sensors (entry IR, exit IR, ultrasonic) transmit simultaneously on shared communication lines.

• Revolutionizing infection control in ICUs: photocatalytic binder materials with platinum nanoparticles (2026) · doi

  The durability and sustained antimicrobial efficacy of binder-incorporated platinum nanoparticle materials under repeated cleaning and disinfection protocols in actual healthcare environments remains untested; longitudinal studies simulating ICU operational conditions are needed to validate real-world performance.

• Piezoelectric stepped-plate resonators vibrating at lateral modes for direct viscosity determination in liquids (2026) · doi

  The piezoelectric stepped-plate resonator was tested only in a temperature-controlled laboratory environment. The dynamic viscosity of Newtonian liquids decreases exponentially with temperature, and silicon-based resonators exhibit negative frequency shifts with temperature due to Young's modulus variation. A temperature compensation algorithm needs to be developed and experimentally validated to correct for temperature-induced variations in Young's modulus under ambient (non-controlled) conditions.

• Data-Driven Approaches to Reliability Modeling in Critical Energy Infrastructure: Analytical Perspectives on Early Failure Detection (2026) · doi

  Standardized imbalance-handling protocols for rare event detection in energy infrastructure are lacking; while resampling and cost-sensitive learning are applied inconsistently across studies, synthetic bias generation and distortion of physical degradation distributions remain unresolved when addressing the class imbalance inherent to early failure detection in critical systems.

• A review of additive manufacturing techniques for wind turbine blade production: capabilities, AI integration, and Scale-Up Potential (2026) · doi

  Standardized benchmarking frameworks for AI-driven defect detection in additive manufacturing of wind turbine blades are absent. Current defect detection performance metrics vary significantly depending on dataset size, defect type, sensing modality, and validation framework, making it impossible to generalize findings across different AM processes and blade geometries.

• PF-Bearing Analyzer: algorithmic implementation of the peak factor method for diagnosing and predicting the technical condition of rolling bearings (2026) · doi

  The peak factor method's frequency range is currently fixed at 6400–25,600 Hz with 4th-order Butterworth bandpass filtering; the paper does not specify optimal frequency ranges for different bearing types, defect locations (inner race, outer race, rolling elements), or rotating equipment operating at various speeds, limiting applicability to diverse industrial scenarios.

• Performance Evaluation of Electric Vehicles Using PSO and AHA Based Optimal Control Methodology (2026) · doi

  The paper demonstrates AHA tuning of Proportional-Integral controllers for EV speed tracking but does not investigate whether the AHA strategy generalizes to other control architectures (e.g., PI-based torque control, model predictive control) or different EV powerertrain topologies (battery electric vehicles vs. plug-in hybrid electric vehicles).

• Elastic Property Anisotropy in Inconel 718 Alloy Specimens Fabricated by Wire Arc Additive Manufacturing (2026) · doi

  While the paper demonstrates that Young's modulus reduction in the Z direction (perpendicular to deposition plane) reaches 10-11% in WAAM Inconel 718 and notes similar patterns in SLS-fabricated specimens, it does not systematically compare quantitative texture characteristics and mechanical property predictions between these two additive manufacturing technologies to establish technology-specific texture-property relationships.

• Modelling the effect of the water evaporation rate on total shrinkage of blended cement concrete (2026) · doi

  The coefficient α in the exponential decay function (Equation 5) was empirically correlated solely to 28-day compressive strength (α = −0.0015fcm + 0.118), despite the acknowledged influence of hydration rate and water-to-binder ratio on shrinkage behavior. Direct experimental quantification of how these material parameters independently affect the decay coefficient across different concrete compositions would improve model mechanistic basis.

• Intelligent performance prediction of nanoparticle-enhanced automotive radiator cooling using CFD and machine learning (2026) · doi

  The CFD simulations were conducted under steady-state assumptions that neglect transient environmental factors including wind speed variation and radiative/conductive heat losses from the radiator surface. The machine learning model trained on these steady-state CFD data therefore cannot predict nanoparticle-enhanced radiator performance under dynamic real-world automotive operating conditions with fluctuating ambient temperature and airflow.

• Nuclear Reactor Chemistry (2017) · doi

  The borosilicate glass waste form is described as resistant to groundwater attack, but the paper does not address long-term glass dissolution kinetics under the specific temperature, pH, and ionic strength conditions expected in deep geologic repositories over timeframes of thousands to millions of years. Experimental and modeling studies of borosilicate glass durability and radionuclide release rates as a function of repository-specific geochemical conditions are required.

• Prediction of unconfined compressive strength of fly ash and waste paper sludge stabilized clayey soil using explainable machine learning (2026) · doi

  Random Forest models demonstrate sensitivity to extreme values in higher unconfined compressive strength ranges with residuals up to ±10 kPa, but the paper does not investigate why this limitation occurs or propose methods to improve prediction accuracy specifically for high-strength stabilized soil samples beyond the dataset range studied.

• AI-driven adaptive vibration control in smart plate systems: a sustainable approach for next-generation sports engineering (2026) · doi

  Material composition optimization is discussed qualitatively for FG-X weight fractions (0.1%-0.4%), but specific design guidelines for selecting optimal material configurations to balance performance and durability in sports plate systems are not provided, limiting practical implementation.