Summary

Eng (ISSN 2673-4117) is an international, peer-reviewed open access journal which publishes original papers, critical reviews, rapid communications, technical notes, and discussions on all areas of engineering. Eng's aim is to encourage scientists to publish their experimental and theoretical research relating to engineering science and technology in as much detail as possible. There is no restriction on the maximum length of the papers. Launched in 2020, Eng was indexed in Scopus in 2023. The journal was subsequently included in the Emerging Sources Citation Index (ESCI, Web of Science) in March 2024 and Ei Compendex in April 2025. It holds a 2025 Impact Factor of 3.5 and is ranked JCR Q1 in the “ENGINEERING, MULTIDISCIPLINARY” category. Its 2025 CiteScore is 4.1, and it currently ranks Q2 in Scopus’ “Engineering (miscellaneous)” category.

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Topic Review
Automatic Welding Techniques
Automatic welding techniques are joining methods in which the welding operation is performed by mechanized or programmable equipment that moves the heat source and controls the welding parameters without continuous manual intervention during production, as distinct from manual welding in which a welder manipulates the torch [1] In these techniques, the welding current, travel speed, wire feed, and torch position are set by a control system and executed by a manipulator, travel carriage, or industrial robot, so that the arc, filler-metal delivery, and joint geometry are maintained according to a predefined program rather than to real-time operator judgment [2]. The term covers mechanized and robotic arc welding, automated gas tungsten and gas metal arc processes, and programmed seam tracking, whose common defining feature is the transfer of the decision and execution of the weld motion from a human operator to automated equipment [1]. Automatic welding is distinguished from automated manufacturing by its focus on the controlled, repeatable deposition of a fusion joint, and from manual welding by the absence of in-process manual manipulation; the welding engineer establishes the procedure and parameters beforehand while the equipment executes them consistently over a production run [2]. These techniques are characterized by parameterized, repeatable execution and by closed-loop control of the weld pool and travel path [3].
  • 9
  • 26 Sep 2026
Topic Review
Retained Austenite
Retained austenite is the face-centered-cubic gamma phase of iron or steel that remains present in the room-temperature microstructure after a heat treatment or processing cycle that, under equilibrium, would have transformed it fully into a room-temperature product such as martensite, bainite, or ferrite [1]. The phase is retained because the martensitic or diffusional transformation is suppressed before completion, typically through chemical stabilization by dissolved carbon and alloying elements, through insufficient undercooling below the transformation temperature, or through mechanical stabilization, so that a fraction of the high-temperature austenite survives at ambient temperature in a thermodynamically metastable state [2]. Retained austenite is distinguished from equilibrium austenite by its metastable, non-equilibrium nature: it persists only because the transformation that should have occurred was kinetically or thermodynamically arrested, and it may subsequently transform to martensite upon cooling below its martensite-start temperature or upon plastic deformation [1]. Its volume fraction, composition, and stability govern its influence on mechanical behavior, because the phase is softer than martensite yet capable of strain-induced transformation, and its identification requires the distinction between stabilized surviving austenite and products that formed in its place [2]. It is a constituent of multiphase steels whose amount and stability are controlled by alloying and thermal history [3].
  • 7
  • 25 Sep 2026
Topic Review
Magnesium Alloy
A magnesium alloy is a metallic material whose principal constituent is magnesium—the lightest of the structural engineering metals, with a density near 1.74 g/cm³—to which one or more alloying elements are deliberately added to modify strength, ductility, castability, corrosion resistance, and elevated-temperature behavior [1]. Alloying elements such as aluminum, zinc, manganese, rare-earth metals, zirconium, and silicon are dissolved in the magnesium matrix or form second phases that produce solid-solution strengthening, precipitate strengthening, or grain refinement, because pure magnesium is comparatively soft and its hexagonal close-packed crystal structure offers limited independent slip systems at room temperature [2]. The alloy is defined by being predominantly magnesium-based rather than by a different base metal with minor magnesium additions, and its mechanical response is governed by this hexagonal lattice, the morphology of intermetallic phases, and grain size [1]. Magnesium alloys are conventionally classified by processing route as cast or wrought alloys and by their dominant alloying system, and their distinguishing material characteristic is an exceptional strength-to-weight ratio arising from the low density of the magnesium matrix combined with the strengthening effects of the additions [2]. Their microstructure consists of an α-magnesium solid solution together with eutectic or precipitate constituents whose distribution determines the resulting properties [3].
  • 11
  • 25 Sep 2026
Topic Review
Battery-Free Sensing
Battery-free sensing is an architecture for sensing devices in which measurement, computation, and communication are performed without an onboard electrochemical battery as the primary energy reservoir, the required electrical power being instead drawn from the surrounding environment or supplied by an external interrogator [1]. The device harvests ambient energy—such as radio-frequency radiation, light, thermal gradients, or mechanical vibration—or receives radio-frequency power radiated by a reader, and uses this energy to operate a sensor, digitize a measurement, and transmit the result, commonly through backscatter modulation of an incident carrier wave rather than by generating a dedicated radio signal [2]. Because the node must function under severely constrained and often intermittent power budgets, battery-free sensing devices are characterized by ultra-low-power electronics, energy-neutral operation, and reliance on the same radio channel that delivers power to also carry the sensed data back to the interrogator [1]. It is distinguished from conventional battery-powered sensing by the absence of a replaceable chemical energy source and by the tight coupling between energy harvesting and communication, in which the act of sensing and transmitting must be sustained by the instantaneous available energy [2]. Such systems typically exploit passive or semi-passive RFID-like principles and are defined by their self-sufficiency and removal of battery-replacement maintenance [3].
  • 5
  • 28 Sep 2026
Topic Review
Heterogeneous Catalysis
Heterogeneous catalysis is the branch of catalysis in which the catalyst and the reactants occupy distinct phases, most commonly a solid catalyst exposed to gaseous or liquid reactants, so that the chemical transformation occurs at the interface between the two phases [1]. The process proceeds through elementary steps that take place on defined surface sites: reactant molecules adsorb onto the catalyst surface, undergo bond breaking and bond formation while bound to surface atoms, and the products desorb to regenerate the active site [2]. Because the reaction is confined to a surface, the activity and selectivity are governed by the geometry and electronic structure of the active sites, the adsorption energies of intermediates, and the morphology and chemical state of the catalyst, rather than by properties of the bulk solid alone [1]. Heterogeneous catalysis is distinguished from homogeneous catalysis, in which catalyst and reactants share a single phase, by this phase separation and by the fact that mass transport and adsorption at the interface are integral parts of the overall rate [2]. The catalyst itself participates in the reaction cycle but is regenerated at the end of each turnover, so it is not consumed, and the microkinetics of adsorbed intermediates determine the observed conversion and product distribution [3].
  • 14
  • 25 Sep 2026
Topic Review
Polymeric Scaffold
A polymeric scaffold is a porous, three-dimensional, biodegradable polymer structure designed to provide a temporary physical and chemical substrate on which cells can attach, proliferate, and organize into functional tissue [1]. The scaffold acts as an artificial extracellular matrix that defines the space to be regenerated while guiding cell migration, nutrient transport, and mechanical loading, and it is intended to degrade in a controlled manner as the neo-tissue matures [2]. Essential structural attributes include high interconnected porosity, a well-defined pore-size distribution, an appropriate surface chemistry for cell adhesion, and mechanical properties matched to the target tissue, because the pore network must simultaneously permit cell ingrowth, vascularization, and diffusion of nutrients and waste while supporting loads [3]. Polymeric scaffolds are typically fabricated from natural or synthetic polymers and their architecture is generated through techniques that control fiber or pore geometry; their defining feature is that they serve as a transient template whose role is to deliver cells and signaling cues rather than to act as a permanent implant [2]. They are distinguished from non-porous polymer implants by their open, interconnected microstructure, which is the basis for their tissue-engineering function [1].
  • 10
  • 25 Sep 2026
Topic Review
Transportation Geotechnics
Transportation geotechnics is the sub-discipline of geotechnical engineering concerned with the behavior of soils, rocks, and geomaterials that support transportation infrastructure such as highway pavements, railway embankments and trackbeds, airfield pavements, tunnels, bridge approach fills, and retaining structures along transportation corridors [1]. It addresses the performance of these structures under repeated cyclic loading from traffic—including the accumulation of permanent deformation in unbound granular layers and subgrades, the effect of moisture and seasonal climatic changes on subgrade strength and stiffness, and the design of rail ballast and capping layers that distribute axle loads from the sleeper to the subgrade without excessive differential settlement [2]. The field applies fundamental principles of soil mechanics, including stress-strain characterization under both static and repeated loading conditions, consolidation settlement, slope stability, seepage and groundwater flow, and frost heave, to the design of embankments, cuts, ground improvement, and foundation systems specific to transportation loading and geometric alignment constraints [3].
  • 8
  • 25 Sep 2026
Topic Review
Nanoporous Materials
Nanoporous materials are solids that contain pore structures with dimensions on the nanometer scale, typically ranging between approximately one and one hundred nanometers, classified by pore size as microporous below two nanometers, mesoporous between two and fifty nanometers, and macroporous above fifty nanometers according to the IUPAC convention [1]. A landmark family of such materials is the ordered mesoporous silicates of the M41S type, including MCM-41, which possesses a regular hexagonal array of uniform cylindrical channels templated by self-assembled surfactant liquid-crystal micelles, yielding very high specific surface area, large pore volume, and narrowly distributed pore diameters that can be systematically tuned by selecting the surfactant chain length and synthesis conditions [2]. The pores are typically characterized by low-temperature nitrogen sorption isotherms using the Brunauer-Emmett-Teller method for surface area determination and the Barrett-Joyner-Halenda method for pore-size distribution analysis, and the materials are structurally characterized through small-angle X-ray diffraction and transmission electron microscopy [3].
  • 8
  • 25 Sep 2026
Topic Review
Precision Engineering
Precision engineering is the discipline concerned with the design, analysis, and manufacture of mechanical systems whose dimensional accuracy, positioning resolution, and surface finish are controlled to sub-micrometer or nanometer tolerances, far below the tolerances of conventional manufacturing processes [1]. The field addresses the fundamental machine-design principles that enable such accuracy: deterministic design based on kinematically located mechanical elements, geometric error budgeting that accumulates the contributions of individual component errors to the final output position, error compensation using closed-loop metrological feedback, and the selection of materials with stable and homogeneous thermo-mechanical properties [2]. Precision engineering also encompasses the metrology required to measure these extremely small dimensions, including laser interferometry, coordinate measuring machines, and atomic-force microscopy, and it rigorously distinguishes between the accuracy of a machine tool, meaning deviation from the nominal target position, and its repeatability, meaning the statistical dispersion of repeated measurements taken under identical and controlled operating conditions [3].
  • 12
  • 25 Sep 2026
Topic Review
Computer-Aided Engineering
Computer-aided engineering is the use of computational software to simulate, analyze, and optimize the performance of engineered products, structures, and processes, predominantly through the numerical solution of governing partial differential equations—most commonly by the finite element method—rather than through expensive physical prototyping and hand calculation [1]. The CAE workflow typically involves discretizing the geometric model into finite elements, assembling the system of algebraic equations for displacement, stress, temperature, pressure, or velocity fields, and solving the resulting sparse matrix system under prescribed boundary conditions and applied loads, so that structural stress distributions, thermal response, fluid flow fields, or electromagnetic behavior can be predicted before physical manufacturing [2]. The method encompasses both linear static analysis and nonlinear, transient, and dynamic analyses, and the reliability of its predictions depends on mesh refinement, element formulation accuracy, material constitutive modeling, and the validation of computed results against physical experimental measurements and full-scale field observations [3].
  • 13
  • 28 Sep 2026
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