Validation gaps in Engineering

Representative open questions

Showing 30 of 143 — 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

  Long-term durability data for BP-modified alkali-activated materials—specifically carbonation resistance, chloride ingress, and sulfate attack for 1–10 year exposure periods in real environmental conditions—are not provided; existing studies focus primarily on 28-day and 90-day compressive strength.

• Experimental insights into phase relations and liquid lines of descent of low- and high-Si boninitic magmas from the Izu-Bonin-Mariana fore-arc (2026) · doi

  Discrepancies in Opx crystallization temperatures (this study: 1094–1205 °C vs. Whattam et al. 2020: 1214–1264 °C) are attributed to three potential causes including melt H₂O estimates, calculation approaches (bulk rock vs. glass composition), and Opx crystallization from different magma primitivity stages. Direct comparative experiments using identical melt H₂O contents and analytical protocols on the same boninite samples are required to resolve these systematic offsets.

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

  The comparison of the BWKOA optimizer with five meta-heuristic algorithms (BO, ABC, ALO, COA, KHO) was conducted only on scenario 1 with identical configurations (25 agents, 50 iterations). Performance comparison across all three wind speed scenarios and with varied population sizes and iteration counts to assess algorithmic robustness has not been performed.

• A novel deep learning approach for accurate and efficient design of LNOI power splitters (2026) · doi

  The DNN model was trained exclusively on Lumerical EME/FDTD simulation data for LNOI power splitters; validation against experimentally fabricated and characterized devices with measured insertion loss, extinction ratios, and spectral response across wavelength ranges has not been demonstrated.

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

  The paper reveals that uneven adhesive application or insufficient drying of the SBR-200 layer may impede mechanical interlock under slant shear conditions, yet no experimental protocol is established to quantify the minimum drying time requirements or acceptable adhesive uniformity tolerances for hybrid bonding systems.

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

  The study observed that interface roughening improved yield strength by 36.36% and UTS by 64.23% in one metal system, but reduced ductility in the dissimilar metal system (ASTM A36-SS316L) with only 25.06% elongation versus 41.16% in substrate. The trade-off mechanism between strength and ductility across different metal pairs requires investigation with additional dissimilar metal combinations beyond the two tested systems.

• A Review on Engineering Approaches to Reverse Osmosis Brine Management: Disposal, Volume Reduction and Emerging Resource Recovery (2026) · doi

  Pretreatment and fouling-resistant membrane material innovations for hypersaline brine treatment require validation data to establish conservative operating envelopes for multistage membrane-based concentration and thermal hybrid processes. Current material screening lacks standardized test protocols for high-salinity, high-fouling-potential brine conditions.

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

  Fatigue, corrosion-fatigue, creep, and stress-corrosion cracking behavior of FSP-treated fusion-welded aluminium joints under service-like conditions (cyclic loading, environmental exposure, elevated temperature) requires extensive experimental investigation to establish design allowables and failure criteria.

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

  Gradient-elastic membrane theory has been applied to wrinkling analysis of stretched thin sheets, but validation against experimental measurements of wrinkle morphology in materials with varying elastic gradients and thickness distributions has not been comprehensively documented.

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

  Machine learning approaches for modeling blast furnace thermal state and productivity prediction using support vector machines and kernel-based methods have been established, but systematic comparison of their accuracy under different burden compositions, wind conditions, and reduction kinetics across multiple furnace geometries is absent.

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

  The interfacial compatibility between Si@MOF anode and PPG electrolyte was demonstrated only at 60°C operating temperature; the thermal stability and interfacial contact maintenance of this system at elevated temperatures (80-100°C) and cryogenic conditions have not been evaluated for solid-state lithium-ion battery applications.

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

  The upper prediction interval contraction of 23.9% post-optimization reduces tail risk, but the paper does not establish whether this contraction maintains adequate coverage for rare or extreme settlement events beyond the 2020–2021 training period. Validation against future or out-of-sample extreme deformation events is needed to confirm that reduced interval inflation does not compromise early-warning reliability under unprecedented hydro-mechanical loading.

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

  Experimental validation of the additively manufactured isolator (Section: Experimental Investigation) is initiated but specific quantitative comparisons between nonlinear FEA predictions and measured transmissibility curves at each temperature (15°C, 25°C, 35°C) are not provided in the excerpt.

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

  The full PISRE configuration (with force signals) is recommended only for 'real-time monitoring and offline analysis contexts' but no experimental validation of its diagnostic capability for tool condition or cutting stability assessment is provided; the complementary diagnostic value claimed for force-dependent branches remains unquantified.

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

  Transitional flow modeling (k-kL-ω transition model with RANS) shows good agreement with MEXICO rotor aerodynamic loads, but combination of transition models with higher-fidelity approaches like DDES for wind turbine rotors has not been comprehensively validated across different Reynolds numbers and operational conditions.

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

  Long-term cycling stability of multifunctional zinc-ion capacitors under operating conditions shows only several hundred cycles achieved in working state, far below practical application requirements. The degradation mechanisms under operating conditions remain underexplored and must be systematically characterized through extended cycling studies.

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

  The cellular packing model simulation (Fig. 26) for predicting particle arrangement at different volume fractions shows promise, but validation against experimentally measured 3D particle spatial distribution in actual nanocomposite films is lacking.

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

  The servo-controlled barrier gate system uses PWM signals to manage entry/exit, but there is no evaluation of mechanical failure modes, actuator lifespan, or fail-safe mechanisms when the servo becomes unresponsive or the gate jamming occurs with vehicles present.

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

  Preliminary investigations demonstrated efficacy against fungal pathogens (Aspergillus niger, Penicillium citrinum, Cladosporium sphaerospermum, Trichophyton mentagrophytes), but these results were not presented in the manuscript; formal validation and quantitative efficacy data for these fungal organisms against the photocatalytic binder materials are required.

• Design of a Three-Operand Binary Adder Using Parallel Prefix Architectures (2026) · doi

  The paper lacks evaluation of the three-operand prefix adder architectures under varying temperature, voltage, and process corner conditions; thermal effects, power supply variations, and manufacturing process deviations on timing performance and power consumption are not characterized.

• Telekit: a bilateral, teleoperated platform for hands-on learning (2026) · doi

  The current stiffness evaluation only tested three discrete material types (sponge, spring, metal) to validate the PF controller's ability to convey qualitative differences in environmental stiffness. Quantitative evaluation across a continuous range of known stiffness values and material types for educational teleoperation scenarios remains incomplete.

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

  The viscosity measurement stability is quantified using standard deviation (SD) and relative standard deviation (RSD) under worst-case conditions, achieving 67 μPa·s and 3.43% RSD respectively. However, long-term stability testing (operational stability over hours or days of continuous measurement) and drift characterization under varying environmental conditions have not been experimentally demonstrated for the AlN-based stepped-plate resonator.

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

  Field validation on longitudinal operational data is lacking; most models are tested on simulated or partially anonymized datasets rather than actual critical infrastructure performance data, reducing empirical credibility and limiting deployment readiness for nuclear and grid system early failure detection.

• DefenDoor: An electromagnetic fingerprint-based access control system with forced-entry detection and SMS notification (2026) · doi

  The forced-entry detection system was tested with only one and two contact sensor setups on a single door configuration. The paper lacks evaluation of the electromagnetic fingerprint-based access control system's alarm and SMS notification performance under varying environmental conditions (electromagnetic interference, magnetic field variations, temperature extremes) or across different door types and materials that may affect electromagnetic sensor sensitivity.

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

  Multimodal sensing systems for AM process monitoring show approximately 22% relative improvement over single-sensor approaches in specific experimental setups, but unified validation protocols comparing multimodal versus single-sensor configurations across different AM techniques and defect types remain undeveloped.

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

  The threshold model defines discrete peak factor ranges (Normal: 3.0, Initial wear: 5.0, Moderate defect: 8.0, Critical defect: 10.0) validated only on outer race defects with varying severity; the paper lacks experimental validation of these thresholds for inner race defects, rolling element defects, and lubrication failures in the same bearing equipment.

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

  The comparison between AHA and PSO is limited to a single competitor algorithm; benchmarking against other metaheuristic optimization methods (genetic algorithms, ant colony optimization, differential evolution) for EV controller tuning would establish the relative performance landscape.

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

  The methodology for predictive assessment of mechanical properties using pole density distribution is validated only against literature data for similar materials, not against independent experimental datasets from WAAM Inconel 718 specimens with varied processing histories or post-processing treatments (heat treatment, machining allowance).

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

  The linear relationship adopted for the time-dependent shrinkage factor Sh(wer, t) during the pre-peak period (Equation 2) was generalized from a single boundary condition based on 38°C room experiments with wer of 0.375 kg/m²/hr. The validity of this linear extrapolation across a broader range of water evaporation rates and diverse environmental exposure conditions (temperature, relative humidity combinations) requires experimental validation.

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

  The paper reports a 5% average deviation between CFD-predicted and experimentally measured outlet temperatures but attributes this solely to steady-state assumptions and heat losses. The specific quantitative contribution of each neglected physical phenomenon (wind speed effects, radiation losses, conduction losses, convection losses) to the CFD-experimental discrepancy has not been decomposed through sensitivity analysis.