Application gaps in Engineering

Representative open questions

Showing 30 of 72 — one per source paper, highest-quality first.

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

  Binder jet 3D printing processes and their material properties have been reviewed, but specific recycling pathways for binder jet-printed parts and quantitative assessment of binder residue effects on mechanical properties during reprocessing cycles remain uncharacterized.

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

  The functional validation protocols for ensuring superelastic plateau integrity over operational lifecycle are mentioned as a prerequisite for SS-NiTi FSW industrialization, but no specific testing matrix, cycling protocols, or acceptance criteria are defined for biomedical or aerospace applications.

• 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.

• 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.

• 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.

• 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.

• 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.

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

  The study reports user satisfaction scores (8-9 out of 10) for the integrated monitoring system but does not conduct systematic usability testing or investigate which specific system features (cost, accuracy, real-time processing, interface design) drive user preference for the fused sensor approach over individual sensors.

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

  Current piezoelectric-photocatalytic systems predominantly rely on high-frequency ultrasonic excitation, but practical material systems capable of efficiently coupling with alternative stress sources such as water flow, gravity, wind, and natural mechanical vibrations have not been systematically developed or characterized.

• 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.

• Multiple-Class Classification of a Diesel Locomotive Engine’s Mechanical Condition Based on Wavelet Properties of Vibration Signals via Machine-Learning Techniques (2026) · doi

  The paper establishes that logistic regression with L1 regularization is suitable for real-time on-board diagnostic systems but does not provide algorithmic specifications for embedded implementation, memory footprint requirements, computational latency analysis, or optimization strategies for deployment on locomotive microcontroller platforms with limited processing capability.

• 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.

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

  While the paper establishes that perovskite surface passivation dominates over ETL modification, it does not investigate whether combining optimized EDG-rich dipolar molecules on both the buried interface and perovskite surface (dual-layer passivation) yields synergistic effects beyond single-interface modification, which is mentioned as desirable but not experimentally validated.

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

  The research describes manipulatives created in workshops (Figures 2-3) for specific mathematical concepts (fractions, geometry, odd/even numbers), but does not empirically measure student learning outcomes or conceptual understanding gains when using DF-created versus commercially available manipulatives across different mathematical domains.

• 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.

• 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

  The paper title emphasizes 'deep learning models' for coal seam porosity and water resources estimation, but the excerpt provided focuses entirely on discrete fracture network methodology, geometric assumptions, and fault/fracture mapping. The integration of deep learning with DFN outputs for regional porosity or water resources prediction is not detailed in this section.

• How to improve the lifespan of electric vehicle batteries using chemistry? (2026) · doi

  Solid-state batteries with solid electrolyte interfaces have unresolved interface connection problems that drive production expenses, but the paper does not specify which interface phenomena (ionic contact resistance, mechanical stress, delamination mechanisms) require investigation to enable cost-effective manufacturing at EV scale.

• Chemical processing routes, crystal structure design and physical parameters of rare-earth doped Sm₂Zr₂O₇ for emerging applications (2026) · doi

  Surface-area enhancement techniques for Sm₂Zr₂O₇ pyrochlores to maximize performance in solid oxide fuel cell (SOFC) applications are mentioned but not defined. Specific surface modification strategies (e.g., nanostructuring, doping, core-shell architectures) and their effects on oxide ionic conductivity for SOFC electrolyte applications require experimental investigation.

• 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.

• 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.

• Artificial neural network-based approach for optimized photovoltaic grid injection using a three-phase multilevel inverter (2026) · doi

  No investigation into the computational complexity and real-time implementation feasibility of the ANN controller on embedded hardware or edge devices.

• Design and Implementation of an IoT-Based 3-Phase Electricity Usage Monitoring System: Case Study at Geophysics Station Class I Sleman, Yogyakarta (2026) · doi

  The monitoring system is limited to non-commercial applications with acceptable tolerance of ±0.5%, but suitability for commercial billing purposes or high-precision industrial energy monitoring remains unvalidated.

• Application of Bernoulli wavelet method on the convective-radiative Fin with heat generation (2026) · doi

  Future research can leverage the BWM to address more intricate geometries, nonlinear boundary conditions, and multi-physics scenarios, further broadening its scope and utility in advanced heat transfer studies.

• BIM Technology in Intelligent Driving Simulation: Potentials and Challenges to Address Virtual Environment Deficiencies (2026) · doi

  The ecosystem of BIM tools and simulation tools have yet to be fully connected; current BIM software (Revit, InfraWorks) is primarily aimed at architecture and engineering rather than intelligent driving applications.

• Thin-film CdTe/CdS/ZnO solar cells and the path to affordable clean energy: Simulation-based evidence for sustainable photovoltaic design (2026) · doi

  Integrating SCAPS-1D output with techno-economic models capable of calculating LCOE as a function of absorber thickness and operating climate would bridge the gap between simulation-derived design optima and deployment-ready engineering decisions.

• Durability of textile-reinforced mortar in acidic environments: effects of acidity level and exposure time on tensile performance (2026) · doi

  The study focuses on tensile performance in laboratory acidic environments; the durability of TRM in real-world acidic exposure scenarios with varying concentrations, temperature cycling, and coupled environmental stresses remains unexplored.

• Enhanced electromechanical coupling in piezoelectric MEMS vibration energy harvesters via strain-induced phase transition in Mn-doped bismuth ferrite epitaxial films (2026) · doi

  The cantilevers were designed to respond to environmental vibration sources with typical frequencies below 200 Hz, but the applicability to higher frequency vibration sources remains unexplored.