Application gaps in Engineering

Representative open questions

Showing 30 of 83 — 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 application of BP in foamed geopolymers, reinforced composites, and zeolitic products is identified as an emerging area, but no specific experimental data, performance benchmarks, or durability testing protocols for these advanced applications have been provided in the literature reviewed.

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

  While the slant shear test demonstrates superior ability to capture combined normal and shear stress effects at the concrete-overlay interface compared to split tensile, bi-surface shear, and push-off tests, the paper does not establish quantitative correlations between slant shear test results and actual in-service bonding performance under complex loading in structural repair applications.

• Eutectogel-Based Drug Delivery Systems: Recent Advancements and Pharmaceutical Applications (2026) · doi

  Regulatory pathways for novel hybrid eutectogel systems combining DES with polymeric, inorganic, or supramolecular components remain undefined; case-by-case regulatory assessment approaches increase approval time and costs for these hybrid drug delivery platforms.

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

  While the roughening strategy was validated on ASTM A36-SS316L bimetallic system, the optimal roughness range of 91.57 μm may not be universally applicable across other material combinations. The study lacks investigation into how material-specific properties (melting point, thermal conductivity, microstructural response) influence the optimal interfacial roughness for different dissimilar metal systems.

• Optimization of drying and packaging strategies for preserving phytochemicals, nutrients, and bioactivity in Bauhinia purpurea petals (2026) · doi

  The cost-benefit analysis comparing freeze-drying at 40°C and 50°C versus cabinet drying and solar drying for Bauhinia purpurea petals was absent; energy consumption and economic viability data are needed for scaled production recommendations.

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

  Halide-based leaching is noted as suitable for severe preg-robbing ores but constrained by corrosion and regulatory factors; systematic laboratory and pilot-scale investigation of corrosion mechanisms in halide systems, materials compatibility, and environmental/regulatory pathways for implementation in different jurisdictions is required.

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

  Energy recovery and staged concentration optimization strategies for reverse osmosis brine systems lack comparative techno-economic analysis across different recovery targets (70%, 85%, 95%) and geographic contexts. Specific energy demand reduction pathways for conservative recovery targets versus near zero liquid discharge systems are not quantified.

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

  Real-time monitoring systems combining force, torque, acoustic emission, and thermal sensors with machine-learning-based adaptive control have not been integrated into FSP operations for fusion-welded aluminium joints to achieve consistent microstructure and mechanical properties across extended weld seams.

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

  XGBoost combined with neural networks has been applied to LIBS spectrum processing for elemental determination in iron ore samples, but the applicability of this hybrid approach to ores from understudied geographic origins and with novel mineralogical compositions remains undetermined.

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

  The PPG composite electrolyte eliminated the need for external pressure (vs. 20-370 MPa required for oxide/sulfide electrolytes), but systematic pressure-dependent electrochemical performance mapping across 0-50 MPa for PVDF-fiber-supported polyethylene oxide/garnet systems has not been conducted to establish minimum pressure thresholds for practical solid-state battery applications.

• Elliptic genera of 2d $$ \mathcal{N} $$ = (0, 1) gauge theories (2026) · doi

  The application of Jeffrey-Kirwan residue methods used in N≥(0,2) quiver gauge theories for BPS state counting and crystal melting models has no established counterpart for N=(0,1) theories; developing analogous statistical mechanical models and crystal melting interpretations for N=(0,1) cases is identified as an open problem.

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

  The harmonic analysis excitation was applied only at the bolt interfaces with 1g swept-sine input in the frequency range 1–350Hz; the response under multi-directional simultaneous excitations (combined x, y, z accelerations as would occur during actual missile flight) has not been experimentally validated.

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

  N/P ratios and areal/volumetric energy densities of zinc-ion capacitors remain far from practical application requirements. Specific targets for N/P ratio optimization, areal energy density thresholds, and volumetric energy density benchmarks need to be established through systematic electrode design and electrolyte formulation studies.

• Smart Security System and Home Automation System: An IoT-Based Approach Using ESP32 and Voice Integration (2026) · doi

  Energy monitoring using ACS712 sensors is listed as an immediate enhancement, but no power consumption baseline for the ESP32 microcontroller in different operational modes, battery runtime estimates, or integration methodology with Sinric Pro cloud service is specified.

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

  While the paper demonstrates that the high-linearity lateral-mode design can be extended to other piezoelectric resonant sensors such as pressure sensors and accelerometers, no concrete experimental or simulation results are provided for these alternative applications. The transferability of the lateral vibration mode optimization strategy and self-sensing capability to non-viscosity sensing devices remains unvalidated.

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

  Long-term field validation data for reinforcement learning-based adaptive control in AM manufacturing systems is limited to selected case studies. Industrial-scale testing of reinforcement learning approaches for reducing downtime and response times in wind turbine blade production environments has not been systematically conducted.

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

  The paper does not specify how the PF-Bearing Analyzer algorithm performs under transient operating conditions (startup/shutdown, load variations, speed changes) or in the presence of structural vibration interference from adjacent rotating equipment, which are common in industrial marine and mechanical systems.

• Design of a green ammonia production process by machine learning (2026) · doi

  The integration of upstream feedstock production (hydrogen and nitrogen sourcing for green ammonia synthesis) with the optimized reactor process design was identified as future work but not executed; the machine learning model's ability to jointly optimize feedstock production parameters and reactor operating conditions remains unexplored.

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

  The paper proposes using quantitative texture analysis to predict mechanical behavior under various loading schemes but provides no validation data for multiaxial loading conditions, cyclic loading, or in-service stress states relevant to the mentioned critical applications in military equipment repair.

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

  Very low water-to-binder ratio concretes (w/b < 0.30) exhibiting high autogenous shrinkage and distinct moisture transport mechanisms were explicitly excluded from model development and validation. The extension of the water evaporation rate model to ultra-high-performance concretes and low w/b mixtures with fundamentally different drying kinetics requires dedicated experimental investigation.

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

  The random forest machine learning model achieved high cross-validation R² values (0.995 for outlet temperature) on the current dataset, but the model's transferability to automotive radiators with different geometric designs, materials, or flow path configurations has not been assessed. Application of this surrogate model to novel radiator architectures requires validation with additional CFD simulations.

• Cyclic hot solvent injection: An advantageous injection method compared with mixture solvent in the solvent based heavy oil mining process (2026) · doi

  The inspiration for gas hydrate production using the CHSI solvent preparation method (high temperature CO₂ extraction of methane) is proposed in Section 3.5 but lacks experimental or simulation validation. Laboratory or numerical studies comparing high temperature CO₂ injection against existing methane extraction methods (depressurization, thermal stimulation, CO₂ replacement) in hydrate sediments are needed.

• Electron transfer mechanism in microbial fuel cells (2026) · doi

  Hybrid MFC systems for simultaneous biohydrogen and chemical production remain underdeveloped; research on integrating hydrogen generation with electron transfer mechanisms and optimizing reactor configurations for dual-output systems (electricity, hydrogen, and chemical production) is absent from current literature.

• Prototyping of self-sustaining propulsion systems for solar system exploration (2026) · doi

  The study identifies that achieving previously unattainable cruising speeds with minimal propellant requires propellant temperatures and pressures that are currently problematic or impossible to achieve. No concrete investigation of these critical thermal and pressure thresholds, nor engineering solutions to overcome them, is presented in the current work.

• A High-Fidelity Numerical Study of Trans-Laminar Fracture in Carbon/Epoxy Laminates Under Varying Environmental Conditions (2026) · doi

  The paper addresses trans-laminar fracture in carbon/epoxy laminates, but the applicability of the numerical model to composite laminates manufactured via automated fiber placement (AFP) with gaps and overlaps, as discussed in reference 24, under environmental conditioning has not been explored for fracture toughness prediction.

• Topotactic engineering of high-entropy (oxy) hydroxide nanotubes for enhanced photocatalysis (2026) · doi

  The photocatalytic evaluation of high-entropy (oxy)hydroxide nanotubes was limited to CIP degradation under UV light (λ = 365 nm) at neutral pH without investigating performance across varied pH conditions, different pollutant types (dyes, phenolic compounds, heavy metals), or visible light wavelengths that would be more practical for environmental applications.

• Smart Electrochemical Sensors and IoT for Monitoring Heavy Metals in Nigerian Water: Review of Advances and Deployment Challenges (2026) · doi

  The paper references seasonal variations of heavy metals in Niger Delta groundwater and surface water but does not specify deployment protocols for electrochemical sensors across different seasonal conditions in Nigerian water systems. Real-time monitoring of how seasonal fluctuations affect sensor accuracy and calibration drift in IoT-enabled heavy metal detection networks requires investigation.

• Design and Development of Fire-Resistant Composites with Fire-Retardant Fillers for Electrical Applications (2026) · doi

  Incompatibilities between organic and inorganic materials are common when using clays like montmorillonite (MMD) and nanoparticles like alumina rehydrate with double hydroxides (LDHs) for flame resistance, requiring further investigation.

• Performance evaluation of the effect of tilt angle on a grid connected photovoltaic power plant using PVsyst (2026) · doi

  Investigating the integration of advanced technologies, such as bifacial PV modules or solar tracking systems, could further enhance system performance.

• Transforming Environmental Waste into Valuable Resources: Characterization of Clayey Sludge from Aggregate Quarries for Sustainable Traditional Ceramics (2026) · doi

  Certain sludge samples require modifications to optimize their properties for ceramic production, with the exception of sample TN1, which appears directly suitable. Enhancing characteristics requires incorporation of clay fractions with higher plasticity, such as smectite or fibrous clays.