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
Unmanned Surface Vehicles
An unmanned surface vehicle (USV), also termed an uncrewed surface vehicle or autonomous surface vessel, is a marine craft that operates on the water surface without a human crew onboard, executing missions through remote control by an operator or through onboard autonomous navigation, guidance, and control systems [1]. The USV comprises the surface hull, propulsion and steering, sensors for environmental perception and navigation, an onboard computing and control system, and a communication link to a remote operator or shore station; the degree of autonomy ranges from fully remote-controlled teleoperation to self-governed operation with limited human supervision [1]. USVs are distinguished from unmanned underwater vehicles, which operate beneath the surface, and from conventional crewed vessels by the absence of onboard personnel; they may operate on inland waters, coastal areas, or open ocean and are governed by maritime collision regulations adapted to uncrewed operation [2]. The platform relies on real-time perception, state estimation, and path planning to maintain station, follow tracks, and avoid obstacles in the presence of waves, currents, and wind disturbances [3].
  • 28
  • 18 Sep 2026
Topic Review
Self-Compacting Concrete
Self-compacting concrete (SCC) is a highly flowable, non-segregating concrete that can flow and consolidate under its own weight, completely filling the formwork and encapsulating congested reinforcement without any mechanical vibration [1]. Its deformability, passing ability, and resistance to segregation are achieved through a powder-rich binder system, reduced coarse-aggregate content (typically below 50% of total aggregate), and the combined use of high-range water-reducing (superplasticizing) and viscosity-modifying admixtures [2]. SCC is characterized by fresh-state tests such as the slump-flow, V-funnel, L-box, U-box, and J-ring tests, which quantify filling ability, passing ability, and resistance to static and dynamic segregation; EFNARC classifies SCC by filling, passing, and segregation-resistance classes and specifies minimum slump-flow ranges by application [1]. Unlike conventional concrete, which requires external vibration to expel entrapped air, SCC achieves uniform consolidation by self-weight while maintaining homogeneity during transport, placing, and finishing, and it exhibits hardened-state properties comparable to those of vibrated concretes of equivalent strength [3].
  • 14
  • 18 Sep 2026
Topic Review
Shapley Additive Explanation
Shapley Additive Explanations (SHAP) is a unified framework for interpreting the predictions of machine-learning models by assigning each input feature a real-valued importance (a SHAP value) for a specific prediction [1]. SHAP values are derived from the Shapley value concept of cooperative game theory, in which the contribution of a player is the average marginal contribution of that player over all possible coalitions of other players [2]. In SHAP, each feature is treated as a player and the model prediction as the game payout, so that the explanation of a particular prediction is decomposed into a baseline value plus the sum of the feature-attribution values [1]. The framework unifies a family of additive feature-attribution methods—including LIME, DeepLIFT, and tree-interception methods—under a common set of desired properties: local accuracy, missingness, and consistency [1]. SHAP distinguishes itself by providing a theoretically unique and consistent attribution under these properties, and by supporting both local explanations of individual predictions and global summaries of feature importance [3].
  • 21
  • 17 Sep 2026
Topic Review
Nuclear Magnetic Resonance
Nuclear magnetic resonance (NMR) is a quantum-mechanical phenomenon in which atomic nuclei possessing a non-zero magnetic moment absorb and re-emit electromagnetic energy when placed in a static magnetic field and irradiated by resonant radiofrequency radiation [1]. In a static field B0, spin-active nuclei precess at the Larmor frequency, which is proportional to B0 and the magnetogyric ratio; the ensemble magnetization then relaxes back toward equilibrium through longitudinal (T1) and transverse (T2) processes described by the Bloch equations [2]. Because the resonant frequency depends on the local electronic environment, the resonance position of a nucleus carries information about its chemical bonding and neighborhood, forming the basis of NMR spectroscopy [3]. The term also covers magnetic resonance imaging, in which spatial gradients encode the resonant signal to produce tomographic images of internal structures [4]. NMR is distinguished from other magnetic resonances by the involvement of nuclear spin rather than electron spin, and from absorption spectroscopy by the use of radiofrequency excitation and phase-sensitive detection [5].
  • 11
  • 17 Sep 2026
Topic Review
Voltage Source Converter
A voltage source converter (VSC) is a power-electronic converter that uses a DC voltage source as its energy-storage element and synthesizes an AC voltage waveform by switching the DC voltage onto the AC terminals through controlled semiconductor devices [1]. The DC side is characterized by a relatively stiff voltage, typically maintained by a capacitor, while the AC-side current is controlled by modulating the magnitude and phase of the synthesized AC voltage relative to the AC system voltage [2]. VSCs are implemented using self-commutated devices such as insulated-gate bipolar transistors, gate-turn-off thyristors, or integrated gate-commutated transistors, which permit independent control of active and reactive power exchange with the AC system [3]. The AC output is generally pulse-width-modulated, with passive filters used to attenuate switching harmonics [2]. A VSC is distinguished from a current source converter (CSC), which uses a stiff DC current source and a series inductor on the DC side, by the nature of its DC-side energy storage and by the quantity that is held constant on the DC side [1].
  • 22
  • 17 Sep 2026
Topic Review
Ultra‑High‑Performance Concrete
Ultra-high-performance concrete (UHPC) is a class of cementitious composite characterized by exceptionally high compressive strength, typically exceeding 120 MPa, together with enhanced durability relative to conventional concrete [1]. UHPC is formulated through a densely packed particle matrix consisting of Portland cement, silica fume, fine sand, quartz powder, and high-range water-reducing admixtures, with a water-to-binder ratio generally below 0.25 and no coarse aggregate in most formulations [2]. Steel or synthetic fibers are commonly incorporated at volume fractions of 1–3% to impart tensile ductility and strain-hardening behavior after cracking [3]. The material exhibits low porosity and permeability owing to optimized particle packing and the pozzolanic reaction of silica fume, which confers high resistance to chloride-ion penetration, freeze–thaw cycles, abrasion, and chemical attack [4]. UHPC is distinguished from high-performance concrete not only by its compressive-strength threshold (typically 120–200 MPa) but also by its fracture energy, post-cracking tensile capacity, and dimensional stability under exposure [5].
  • 30
  • 17 Sep 2026
Topic Review
Total Harmonic Distortion
Total harmonic distortion (THD) is a power-quality metric that quantifies the harmonic content present in an electrical voltage or current waveform relative to its fundamental component [1]. For a periodic waveform, THD is defined as the ratio of the root-sum-square of the amplitudes of all harmonic components—excluding the fundamental—to the amplitude of the fundamental component, usually expressed as a percentage [2]. The harmonics considered are integer multiples of the fundamental power frequency and arise from nonlinear loads and power-electronic converters [3]. THD may be evaluated for voltage (THD_V) or current (THD_I); a higher THD indicates a waveform that deviates more strongly from a pure sinusoid [2]. THD is distinct from total demand distortion (TDD), which normalizes harmonic current to the maximum demand current rather than to the fundamental [1]. Limits on harmonic distortion at the point of common coupling are established in power-quality standards, and THD serves as the primary figure of merit for waveform quality in such assessments [3].
  • 22
  • 17 Sep 2026
Topic Review
Printed Circuit Board
A printed circuit board (PCB) is a rigid or flexible insulating substrate onto which conductive pathways, pads, and other features are patterned in order to mechanically support and electrically interconnect electronic components [1]. The conductive patterns are typically formed from copper laminated to the substrate and etched or plated to define traces, with plated-through holes or vias connecting conductive layers in multilayer constructions [2]. Components are mounted onto the board by soldering to pads that are themselves integrated into the patterned copper layer [1]. The substrate materials are commonly glass-reinforced epoxy laminates, polyimide, or other dielectric materials selected for mechanical rigidity, thermal stability, and electrical insulation [2]. A PCB is distinguished from a bare printed wiring board by the inclusion of patterned conductive features that form a defined circuit, and from a backplane by the integration of active and passive components as well as interconnects [3]. Design and manufacturing requirements for PCBs—including conductor width, spacing, dielectric thickness, and via geometry—are standardized in industry specifications [3].
  • 12
  • 17 Sep 2026
Topic Review
Pavement Condition Index
The Pavement Condition Index (PCI) is a numerical rating on a 0–100 scale that expresses the surface condition of a pavement section, where 100 denotes a pavement in perfect condition and 0 denotes a failed pavement [1]. The PCI is derived from a standardized visual survey in which trained inspectors identify visible surface distresses, classify each by severity level (low, medium, high), and measure its quantity over defined sample units [2]. Deduct-value curves convert the distress inventory into weighted deductions, which are then combined by an optimized combination procedure — originally developed for the U.S. Army Corps of Engineers — to yield a single PCI value for each sample unit and, by aggregation, for the section or network [1][3]. The PCI is an indirect measure of structural integrity and functional surface condition; it is not a direct measure of structural capacity, skid resistance, or ride roughness [2]. The method applies to both asphalt concrete and Portland cement concrete pavements, each with its own distress catalog, and is standardized in ASTM D6433. It is distinguished from profile-based indices such as the International Roughness Index by being distress-based rather than measurement-based.
  • 22
  • 17 Sep 2026
Topic Review
Solar Power Plants
A solar power plant is a centralized, grid-connected installation that converts solar radiation into electrical energy, either by photovoltaic (PV) modules exploiting the photovoltaic effect in semiconductor cells or by concentrated solar thermal (CSP) collectors that concentrate sunlight to heat a working fluid driving a thermodynamic cycle [1]. In a PV-based plant, many modules are grouped into strings and arrays, and their direct-current output is collected and inverted to alternating current; in a CSP plant, heliostats or parabolic troughs focus radiation onto a receiver that supplies steam or thermal oil to a power block [2]. The plant integrates tracking or fixed mounting, DC collection, power-conversion equipment, step-up transformers, and a dedicated point of interconnection, and is rated by its installed capacity in megawatts [3]. It is distinguished from distributed rooftop PV by its centralized scale, dedicated land or structure, and connection to the transmission or distribution system rather than the on-site load of a single dwelling [4].
  • 8
  • 16 Sep 2026
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