Methodology gaps in Engineering

Representative open questions

Showing 30 of 119 — one per source paper, highest-quality first.

• Power-Optimized AI-Enhanced Telepresence Robots: A Validated Multi-Modal Framework for Sustainable Remote Learning in Higher Education (2026) · doi

  Battery endurance is currently unspecified in tested configurations; expansion to 8-10 hour operational periods using 6000 mAh high-capacity cells requires hardware redesign and power-consumption validation to confirm the 35% energy reduction advantage is maintained.

• Challenges and Frontiers in the Circularity of Polymer Additive Manufacturing: A Systematic Review of Recycling Pathways and Material Degradation (2026) · doi

  The degradation behavior of PA12 powder in selective laser sintering during reuse cycles has been characterized for material characteristics and dimensional accuracy, but the relationship between specific powder recycling cycles (e.g., 1st, 2nd, 3rd reuse) and the onset of irreversible degradation thresholds in mechanical strength remains incompletely mapped.

• Friction Stir Welding of Dissimilar Materials: A Comprehensive Study on Joining Stainless Steel to Ni, Ti, and NiTi Alloys (2026) · doi

  Non-Destructive Testing (NDT) standards for validating the shape memory effect degradation inside SS-NiTi weld nuggets do not exist; the paper acknowledges this as a critical threat to industrialization but provides no methodology for detecting functional drift of the superelastic plateau post-welding.

• 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.

• Electrically switchable continuous phase liquid crystal Fresnel zone plate (2026) · doi

  The current 20 µm LC layer thickness was constrained by the axial voxel size limitations of the present two-photon photopolymerization direct laser writing (TPP-DLW) system. Specific experimental investigation is needed to determine the minimum achievable LC layer thickness when using higher numerical aperture (NA) objectives to reduce z-voxel size, and how this thickness reduction quantitatively affects the rise time according to the τrise ∝ d² relationship (Equation 3).

• 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.

• High-Entropy Catalysts for Biomass-Derived Chemicals Valorization: Mechanisms, Applications, and Opportunities (2026) · doi

  The relationship between crystal engineering strategies (FCC, BCC, HCP structures in HEAs and rock-salt, perovskite, spinel, fluorite structures in HE ceramics) and biomass valorization catalytic performance remains unexplored. The impact of exposed crystal facets and atomic configurations on selective conversion of recalcitrant platform compounds like HMF and lignin requires in-depth investigation.

• 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.

• 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

  The physics-informed constraints embedded in Branches A and C (e.g., Rath, Achip, ln(1 + Rath)) are derived from established Ti-6Al-4V cutting mechanics but no comparison is provided between PISRE-NF and alternative physics-derived feature sets or Bayesian optimization of the constraint set across different material classes.

• 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.

• Sensor Data Fusion in Healthcare Monitoring System with Appropriate Rule-based Model for Error Reduction (2026) · doi

  The fused sensor system achieved only 5 hours of battery durability compared to 10 hours for individual blood pressure sensors, yet the paper does not investigate optimization strategies for reducing power consumption in multi-sensor fusion architectures or present methods to extend battery life in the integrated healthcare monitoring system.

• A review: recent progress of piezoelectric effect coupled photocatalytic reaction: diverse mechanisms, system/structure design, characterization and application (2026) · doi

  The mechanisms underlying piezoelectric potential switching effects and orthogonal charge transport in composite piezoelectric-photocatalytic systems have been proposed but require fine-scale structural design using layer-by-layer assembly, interface engineering, or epitaxial growth to control spatial positions and orientations of components and enable directed charge carrier migration.

• 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.

• Chemistry of Carbon and Hydrogen (2019) · doi

  The text describes carbon allotropes (diamond, graphite, fullerene, coal, charcoal, coke) but does not address the synthesis parameters, yield optimization, or structural characterization methods required to controllably convert between amorphous forms (charcoal, lampblack) and crystalline allotropes under specific temperature and pressure conditions.

• 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.

• Electron-donor/-acceptor ratio-guided molecular engineering for buried interface optimization in n-i-p perovskite solar cells (2026) · doi

  The study demonstrates that EDG-rich dipolar molecules enhance perovskite surface passivation more effectively than ETL modification, but does not systematically investigate the optimal EDG/EWG ratio threshold across different perovskite compositions or device architectures. Future work should experimentally map EDG/EWG ratio dependencies for various halide perovskites (MAPbI3, FAPbI3, mixed-cation formulations) to establish composition-specific design principles.

• Transfer-learning guided design of high-performance conjugated polymers for low-voltage electrochemical transistors (2026) · doi

  The paper does not address how processing conditions (e.g., edge-on polymer alignment, deposition rate, annealing temperature) affect the transferability of machine-learning predictions for low-voltage electrochemical transistor performance; the interaction between learned molecular features and device fabrication parameters remains unexplored.

• Unpacking Teachers’ Transformative Agency Following Digital Fabrication Workshops on Making Mathematical Manipulatives (2026) · doi

  Teachers reported insufficient competence in handling laser cutters independently and requested additional training in 2D/3D modeling and digital fabrication tool operation. However, the paper does not specify which modeling software types, skill levels, or training duration would be most effective for teachers to achieve proficiency in creating manipulatives with digital fabrication technologies.

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

  Hybrid manufacturing techniques combining subtractive processes with additive manufacturing for wind turbine blade production have not been comprehensively investigated. Development of integrated AM-subtractive hybrid workflows and their scalability to utility-scale blade manufacturing requires systematic research.

• Coal seam porosity and water resources estimation based on big data analysis and deep learning models: A case study in the Surat Basin, Australia (2026) · doi

  Fracture aperture in the DFN model is stated as 'will be figured out by matching DST data,' but the paper does not explicitly detail the methodology for inverting drill stem test data to constrain fracture aperture values or validate aperture estimates across the three tested coal seams (DST1, DST2, DST3) at well Dalwogan 2.

• 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).