Search Results (865)

Acoustic emission (AE) measurements have many uses to evaluate the integrity of materials. AE is often used to detect leakage in pipelines. It has also been used to monitor changes in strength properties of fiber-reinforced concrete. In the oil and gas industry, AE is predominantly used to study fracture initiation and propagation. In particular, characterization of samples is key for evaluating subsurface formations for successful underground storage. Research has been performed to understand the behavior of AE in uniaxial compression and single-stage triaxial compression tests. However, the validity of this method has not been documented in a multistage triaxial test. This characterization is required to understand the stability of the host rock under the related stress changes and potential mineralogical changes that may occur. Typically, there is a shortage of geologic samples. A single multistage triaxial test eliminates the need for twin samples and provides an economic and time-saving protocol compared to conventional methods. A single multistage triaxial (MST) test allows a constitutive model to be developed for a host rock. This work establishes a protocol for performing these tests with minimal corrections to the measurements. Acoustic emissions were measured on five different samples undergoing multistage triaxial tests. Two different behaviors were observed. For the coarse grained samples, designated Group 1 (Miocene sandstone, Wilcox Formation, and Cambrian sandstone), the number of AE events did not show a strong dependence on confining stress. They did show an exponential increase in AE events with increasing deviatoric stress during each stage. In contrast, the Group 2 samples (Niobrara Marl and Niobrara Chalk) exhibited significantly different stress-dependent AE behaviors. The amplitude of the AE events is significantly smaller than in the quartz-dominated samples, indicating a more ductile and diffuse failure mechanism. The correlation between maximum compressive strength and the point of positive dilatancy is 1.2 for both groups of samples, even though a different pattern of AE events is observed. Full article

Advanced manufacturing and cutting machinery often operate under variable material properties and uncertain load conditions, making real-time process optimization difficult when high-fidelity simulations and physical experiments are costly. To address this problem, this study proposes a physics-guided surrogate-assisted reinforcement learning framework for multi-objective speed regulation of coal–rock cutting machinery. The haulage speed and drum rotational speed are jointly optimized to balance production rate, cutting specific energy consumption, current load, vibration impact, and speed-regulation stability. First, an EDEM–RecurDyn–Simulink co-simulation model was established to obtain cutting current and vibration response data under different coal–rock structures and speed combinations. Similar-material cutting experiments were conducted to validate the vibration response, with root mean square (RMS) relative errors of 3.38%, 4.21%, 5.75%, and 5.03% under full-coal, single-gangue-layer, double-gangue-layer, and full-rock conditions, respectively. Based on these data, an improved physics-informed neural network (PINN) surrogate model was developed by embedding an equivalent coal–rock difficulty factor, a speed-matching factor, a semi-empirical current prior, and a vibration residual calibration mechanism. The surrogate model achieved R² values of 0.9623 and 0.9147 for cutting current and vibration kurtosis, respectively. It was then integrated into a Soft Actor–Critic (SAC) control environment to learn continuous dual-variable speed-regulation policies. Across five independent SAC training seeds, the improved SAC achieved an average theoretical productivity of 207.8033 ± 6.5641 t·h⁻¹ and a cutting specific energy consumption of 0.3387 ± 0.0114 kW·h·t⁻¹. Compared with the fixed-speed, empirical speed-regulation, and conventional SAC strategies, the proposed method increased the average theoretical productivity by 2.65%, 5.01%, and 1.77%, respectively, while reducing the corresponding specific cutting energy consumption by 1.37%, 4.05%, and 2.22%. These results demonstrate that the proposed framework provides an efficient intelligent optimization method for condition-aware speed regulation in complex industrial cutting processes. Full article

Cement production generates approximately 7% of global CO₂ emissions; Jordan’s kilns run on petroleum coke, coal, and olive residue with no demonstrated solar thermal integration for pre-heating. This paper addresses that gap and presents the first plant-data-backed techno-economic and environmental assessment of a hybrid dual-stage concentrating solar thermal system integrated into the pre-heater tower of a cement plant in Ma’an, Jordan (30.2° N, direct normal irradiance (DNI) = 2749 kWh/m²/yr). The study objectives are to (i) characterize Stage 5 and Stage 6 thermal loads from real plant operating data; (ii) size and simulate a 6000 m² parabolic trough collector (PTC) field with molten-salt thermal energy storage (TES) targeting Stage 5 (380 °C, 3200 kW) and an 8000 m² Linear Fresnel Reflector (LFR) field with rock/PCM TES targeting Stage 6 (300 °C, 2200 kW); (iii) quantify the combined solar fraction, fuel savings, and CO₂ avoidance; (iv) conduct a Jordan-specific cost analysis benchmarked against NREL 2015 solar heat for industrial process (SHIP) data under three CAPEX scenarios; and (v) evaluate net present value (NPV) at two discount rates with and without carbon credits. The PTC field achieves a Stage 5 solar fraction of 35.5%, and the LFR field achieves 50.0% at Stage 6, yielding a combined annual solar fraction of 41.4% and displacing 59,384 GJ/yr (4163 t CO₂/yr). Under Jordan base-case CAPEX of $3.89 M, 6% concessional finance, and a $50/t CO₂ carbon credit, NPV reaches +$1.11 M with a breakeven carbon credit of $29/t CO₂. These results confirm commercial viability under accessible green finance and carbon pricing, providing a replicable model for cement kiln pre-heater decarbonization in high-DNI Middle East and North Africa (MENA) countries. Full article

Spacing design for group cable bolt systems remains largely empirical and rarely considers stress interaction and displacement overlap together. This study develops a dual-index interaction framework for two representative cable bolt configurations in deep stope roofs. Mindlin’s semi-infinite body solution and Kelvin’s infinite body solution were combined with a non-uniform interfacial shear stress distribution to model shallow fully grouted and deep end-anchored systems, respectively. The analytical trends were examined using FLAC3D, and the field applicability of the selected spacing scheme was assessed through an industrial test at the Fankou Lead–Zinc Mine. The results show that the fully grouted configuration is strongly affected by the free surface and full-length load transfer, whereas interaction in the end-anchored configuration is concentrated around the deep bonded section. The stress interaction coefficient $\eta$ provides the primary screening measure for a reference lower spacing bound, while the displacement interaction coefficient $\alpha$ identifies residual displacement overlap. Both are local field interaction indices rather than measures of individual cable capacity or global system stiffness. Using ${\eta }_{\mathrm{ref}}$ = 0.9 as an engineering tolerance, stress interaction becomes limited at approximately $s/D$ = 30 for the end-anchored configuration, whereas the fully grouted configuration enters a relatively stable interaction–attenuation stage at approximately $s/D$ = 40. Considering both configurations, $s/D$ ≈ 40 is adopted as a reference lower bound, corresponding to 1.6 m for a 40 mm borehole. The field scheme used a spacing of 1.8 m ($s/D$ ≈ 45) and produced a maximum measured roof displacement of 27.6 mm, with no evident roof fall, cable breakage, or anchorage pull-out. Because characteristic rock mass heterogeneity is not explicitly represented and only one field spacing was tested, the proposed spacing ratio should be regarded as condition-specific rather than universal. Full article

Ultrawide bandgap (UWBG) semiconductors are destined to become the foundation for next-generation power and radio-frequency (RF) electronic devices. Their superior qualities such as high thermal conductivity, strong critical electric field, and robust mechanical and radiation hardness are driving continuous and widespread research. Amongst the UWBG materials, aluminum nitride (AlN) is highly attractive due to its direct ultrawide bandgap of about 6.2 eV, resulting in one of the highest Baliga’s and Johnson’s figures of merit. Equally important as its properties are material availability and growth methods capable of producing large-diameter substrates. In this work we report on bulk growth of 100 mm AlN crystals using the physical vapor transport (PVT) technique. The thermal gradients were simulated and tailored to obtain adequate thermal stresses, resulting in substrates with narrow X-ray rocking curves and dislocation densities in the range of 10²–10⁵ cm⁻². In addition, the room-temperature thermal conductivity measured in two directions, perpendicular and parallel to the c-axis, was confirmed to be 300 W m⁻¹ K⁻¹. AlN substrates also demonstrated high UV transparency with absorption coefficients as low as 10 cm⁻¹ at 265 nm wavelength. These results, along with the availability of 100 mm substrates, demonstrate that AlN is ready for further exploration and development for the power and RF electronics industry. Full article

This study introduces an integrated, reverse-engineering-driven framework for optimizing automotive connecting rods under real-world industrial constraints. The geometric characteristics and material composition of a legacy component were experimentally characterized using high-resolution 3D scanning (Artec Spider Studio 16) and spectroscopy. The resulting data were incorporated into the optimization workflow. Computer-aided design tools, including SolidWorks 2022^® Premium 2022 × 64 (Dassault Systèmes SolidWorks Corporation, Waltham, MA, USA) and Geomagic Design X 2022 (3D Systems, Rock Hill, SC, USA), captured precise geometry, while spectroscopy confirmed cast iron as the base material. An upgrade to structural steel is proposed, offering the potential for improved strength-to-weight performance. Although reverse engineering and topology optimization are well-established, previous studies have largely focused on idealized models and unconstrained domains. ANSYS Workbench 2022 R1 (ANSYS Inc., Canonsburg, PA, USA) topology optimization is constrained to preserve functional interfaces and manufacturability. Motivated by the demand for lightweight automotive solutions in the Middle East, this workflow achieves 2.63% mass reduction and an estimated 6.6% cost savings based on prior benchmarks. Incorporating the Octet lattice structure (nTopology, 2022 (nTopology Inc., New York, NY, USA)) further improves performance, yielding a 6.4% mass reduction and a 16% cost reduction. The optimized design is considered a promising candidate for future additive manufacturing and Industry 4.0 implementation. This preliminary procedure provides a transferable template for redesign, static evaluation, and experimental validation of legacy components, bridging the gap between academic research and industrial practice. Full article

Understanding the hydrochemical characteristics of groundwater in coal mining subsidence areas is of critical scientific significance for water environment protection and ecological restoration in mining regions. A systematic hydrochemical campaign was undertaken in the Luwa collapse zone (Jining city, Shandong Province) to decipher the composition, evolutionary behavior, and governing factors of groundwater within a high-water-table subsidence context. The analytical protocol comprised three complementary components: conventional hydrochemical profiling, ion-ratio-based source identification, and multivariate statistical modeling. The findings revealed that the groundwater in the study area was weakly alkaline (pH = 7.33 ± 0.217), with total dissolved solids (TDS) ranging from 1180 to 2280 mg/L, and all sampled sites exceeded the Class III groundwater quality standard of China. Na⁺, SO₄²⁻, and Cl⁻ were identified as the predominant pollutants, with exceedance rates of 91.3%, 95.7%, and 91.3%, respectively, which were primarily attributed to coal mine drainage and domestic sewage input. The groundwater chemical composition was governed by the combined effects of rock weathering, evaporation–concentration processes, and anthropogenic activities. Specifically, Na⁺ and Cl⁻ originated mainly from the dissolution of silicate minerals and halite, as well as domestic sewage input; SO₄²⁻ was primarily controlled by evaporite dissolution and industrial wastewater discharge; carbonate and silicate mineral weathering was identified as the primary source of Ca²⁺ and Mg²⁺; and NO₃⁻ was predominantly influenced by agricultural activities. Principal component analysis (PCA) extracted three major controlling factors shaping the groundwater hydrochemistry in this area, namely: (1) evaporite dissolution and sewage input, (2) carbonate dissolution and pH buffering processes, and (3) agricultural input. This study reveals a dual-driven evolutionary model of groundwater in high-water-table coal mining subsidence areas, characterized by “natural enrichment superimposed by anthropogenic input,” whose work contributes to the knowledge base for sustainable groundwater stewardship and contamination risk reduction in mining-affected areas with analogous conditions. Full article

The formulation of organomineral composts can be used to modulate nutrient dynamics and improve the quality of fertilizers produced from agro-industrial residues. This study evaluated the effects of compost formulation, phosphorus source, and inoculation with phosphate-solubilizing bacteria on nutrient dynamics during the composting of sugarcane filter cake. Six formulations combining filter cake, poultry litter, and agricultural gypsum were evaluated: organic compost (T1); compost enriched with reactive phosphate rock (T2); reactive phosphate rock + phosphate-solubilizing bacteria (T3); triple superphosphate (T4); triple superphosphate with a modified filter cake-to-poultry litter ratio (T5); and compost without gypsum (T6). The experiment was conducted in a completely randomized design with five replicates, and composts were evaluated at 45, 65, and 115 days. Data were subjected to analysis of variance considering formulation, composting time, and their interaction. A significant interaction between compost formulation and composting time was observed for organic matter, organic carbon, P, K, Ca, Mg, and pH, whereas N and S were independently affected by these factors. Organic matter and organic carbon contents decreased by 18% and 19%, respectively, at 115 days compared with the earlier composting periods. P-enriched formulations had 52% higher P content than non-enriched composts, while T2 and T5 showed comparable P content. Inoculation with phosphate-solubilizing bacteria temporarily increased P content during the composting phase, whereas gypsum did not improve N conservation. These findings demonstrate that formulating composts with reactive phosphate rock is a technically feasible strategy for producing P-enriched organomineral fertilizers while promoting nutrient recycling and the valorization of agro-industrial residues. Full article

Although uncertainties regarding natural hydrogen (H₂) reserves remain high, exploration activity is expanding across several countries. To date, the only active production site uses this resource locally for electricity generation; however, operating companies could target industrial markets where H₂ can serve as both an energy source and a chemical feedstock. Surface constraints and proximity to commercial markets will dictate distribution and utilization strategies when alternative options are available. This study introduces a novel tool that integrates surface and subsurface constraints to rank prospective exploration areas, enabling companies to identify opportunities aligned with their specific corporate profiles or business plans. The methodology is applied to western Colombia, a region characterized by many surface constraints and known H₂-generating source rocks; H₂ surface emanations have also been documented. Western Colombia is structurally divided by north–south mountain ranges (Cordilleras) that severely hinder east–west transportation and contribute to regional energy insecurity. Using a comprehensive data compilation, this study demonstrates how applying different weighting schemes to diverse geographical and geological parameters can optimize site selection. The Medellín area ranks highest if the target is the industrial market. Full article

The reactive transport of hexavalent chromium (Cr(VI)) in anthropogenically disturbed sites (e.g., mine waste rock dumps, chromium salt industrial sites) is critically influenced by physico-chemical heterogeneity, yet the interplay between physical and chemical heterogeneities remains poorly understood. This study employed a series of experiments and numerical modeling to investigate the transport of Cr(VI), focusing on the implications of physical heterogeneity—represented by preferential flow paths—and chemical heterogeneity—characterized by reductive mineral lenses. Key findings indicate that physical heterogeneity accelerates Cr(VI) breakthrough by 1.4 to 2.1 pore volumes (PV) relative to homogeneous columns. The presence of pyrite lenses delays breakthrough by 0.6–1.2 PV under neutral pH and 1.6–2.0 PV under acidic pH. At a flow rate of 3.0 m/day, the apparent sorption capacity decreases by ~62.5% compared to 0.3 m/day, indicating that physical advection largely suppresses chemical retention under high-flux conditions. The above results demonstrate that physical heterogeneity governs flow paths and advection rates, whereas chemical heterogeneity impedes transport through heterogeneous adsorption and reduction in Cr(VI) to Cr(III) along these pathways. Furthermore, the presence of preferential paths leads to greater spatial variability, which subsequently influences the interaction dynamics between Cr(VI) and reactive minerals in the aqueous environment. The dominance shifts between physical/chemical controls based on flow rates and pH. At higher flow rates, the influence of physical heterogeneity becomes more pronounced, diminishing chemical reactions due to insufficient residence time of Cr(VI). Conversely, a lower pH environment enhances pyrite dissolution, which decouples the dependency on physical heterogeneity by promoting homogeneous reactions. Further evidence was obtained through X-ray photoelectron spectroscopy (XPS) analysis. The experimental observations are complemented by TOUGHREACT-based reactive transport simulations, which further reveal that the apparent dominance shifts arise from competing timescales between advection and surface reaction. The insights gained from the study emphasize the necessity of integrating both physical and chemical spatial variability in risk assessments, transport modeling, and designing targeted remediation strategies. Full article

Lithium, as a Li-ion battery constituent, is pivotal for the transition to clean energy. Western Australia (WA) has become a global leader in hard-rock lithium mining, realising 10-fold growth from 2010 to 2024 and with royalty receipts to the WA government surpassing $1 billion AUD. Given the sector’s economic significance, we analyse key performance metrics including resource/reserve build, production growth, cumulative capital deployed, capital intensity, and development timelines for the new-generation lithium mines. Several enabling factors supported the rapid build-out of capacity. These include an efficient mine permitting process to manage environmental impacts and competing land use issues, a stable royalty regime, energy and logistics infrastructure, availability of a skilled workforce, and mining services capability. Contrary to the standard industry narrative that new mineral projects are constrained by legislative delay, the new lithium projects achieved development timelines of 7 years or less from first resource to production. This has broader implications for critical mineral projects where success is likely to depend less on strategic classification and more on project quality, financing, and regional capability. Full article

The East Kazakhstan Region is characterized by heterogeneous mountain, steppe, agricultural, and urban–industrial landscapes. However, spatially integrated assessments of land-cover conditions, agricultural dynamics, settlement expansion, and atmospheric trace-gas patterns remain limited. This study combines open multi-source Earth observation datasets and products to assess regional land cover, cropland dynamics from 2003 to 2019, built-up-area expansion from 1985 to 2025, and tropospheric nitrogen dioxide (NO₂) column density from 2019 to 2024. The land-cover classification was based on Sentinel-2 imagery and ancillary geospatial datasets. Its random forest component achieved an overall accuracy of 90.17%, a Cohen’s kappa coefficient of 0.892, and a macro-averaged F1 score of 0.888. Grassland was the largest mapped land-cover class, covering 39.3% of the study region, followed by dense vegetation (16.2%), rock (14.9%), and sparse vegetation (10.6%). Mapped cropland extent increased from 4771.6 km² in 2003 to 5043.9 km² in 2019, representing a net increase of 272.3 km² (5.7%), although a minor decrease occurred after 2015. The harmonized built-up area time series showed expansion within all nine major settlements, with the largest absolute increase observed in Öskemen (Ust-Kamenogorsk). Newly detected built-up pixels during 2000–2024 were mostly associated with transition from grassland and dense shrubs. Annual Sentinel-5P observations showed recurring elevated tropospheric NO₂ column densities in northwestern East Kazakhstan, particularly around Öskemen. Over the built-up footprint, the area-weighted mean increased from 24.1 µmol m⁻² in 2019 to 29.2 µmol m⁻² in 2024. The integrated framework provides a spatially consistent regional baseline while identifying descriptive patterns that require further process-based investigation in future. Full article

Waste rock wool (WRW) has attracted increasing attention as a supplementary cementitious material (SCM) because of its mineral composition and its potential for reducing industrial waste. Although thermal treatment is commonly applied during WRW recycling, the practical necessity of additional low-temperature thermal treatment after mechanical activation remains unclear. This study evaluated the feasibility of mechanically activated WRW as an SCM by comparing materials with and without subsequent thermal treatment at 250 °C. Cement paste containing 15 wt.% WRW was prepared, and the effects of thermal treatment were evaluated through X-ray fluorescence (XRF), scanning electron microscopy (SEM), compressive strength testing, and thermogravimetric analysis (TGA). The XRF and SEM results revealed only negligible differences in chemical composition and particle morphology between the thermally treated and non-thermally treated WRW. Although both WRW mixtures exhibited lower early-age compressive strengths than the Plain mixture, comparable or higher long-term strengths were achieved. The TGA results also showed only minor differences in calcium hydroxide content and degree of hydration between the two WRW mixtures. Overall, additional low-temperature thermal treatment provided limited practical benefits beyond mechanical activation alone. These findings demonstrate that mechanically activated WRW without subsequent thermal treatment is a feasible supplementary cementitious material, offering a simplified and more energy-efficient recycling strategy for cementitious applications. Full article

Precise station-keeping of construction barges during offshore operations remains a demanding control problem because the underlying dynamics are highly nonlinear and the disturbance environment is seldom known a priori. This work investigates how a learning-based controller can be embedded into the coordinated winch-control architecture of a specialized engineering vessel to deliver accurate positioning in shallow water. Vessels such as rock-dumping platforms and pipe-laying barges routinely rely on a spread of mooring lines to hold station, and the tensions on these lines are, in current industrial practice, still adjusted manually by the winch operator. The scheme proposed here replaces that manual loop with an adaptive neural feedback law synthesized through backstepping, allowing the unknown portions of the ship model and the exogenous environmental loads to be compensated online without requiring prior identification. The 3DOF control wrench produced by the feedback law is then mapped to the physical line tensions through a constrained allocation that respects the unilateral and breaking-load constraints of the spread. The closed-loop system is shown to be semi-globally uniformly ultimately bounded (SGUUB) in the Lyapunov sense, and its performance is benchmarked against a conventional PD regulator and a nominal model-based design through simulation of a full-scale rock installation barge. When the model-based baseline is given the nominal plant, it attains the cleanest tracking; the proposed neural law achieves comparable steady-state accuracy without requiring prior identification of the hydrodynamic coefficients. A model-free deep reinforcement learning (PPO) controller is additionally benchmarked under irregular (JONSWAP) seas; it attains bounded sub-metre station-keeping without any model knowledge, on par with the PD baseline but less precise than the model-based and adaptive-neural laws. Full article

Groundwater is a critical resource for domestic, agricultural, and industrial use in the Gilgel Gibe and Dhidhessa catchments of southwestern Ethiopia, where volcanic aquifer systems are the main sources. However, groundwater quality in these catchments has been under pressure from anthropogenic activities such as population growth, land-use changes, and pollution driven by rapid development and poor resource management. This study investigates hydrogeochemical processes and evaluates groundwater quality in volcanic aquifers using hydrochemical analyses and a stable isotope approach applied to 115 water samples. The spatial distribution of various physicochemical and hydrogeochemical parameters shows a distinct contrast between the highland and lowland regions, indicating topography-driven variations in water quality and geochemical processes. In hand-dug wells, springs, and surface waters, the ionic order is Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ and HCO₃⁻ > NO₃⁻ > Cl⁻ > SO₄²⁻, whereas deep wells show Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and HCO₃⁻ > Cl⁻ > SO₄²⁻ > NO₃⁻. The predominant groundwater type is Ca-HCO₃, followed by Na-HCO₃ and Ca-NO₃, with other types including Ca-Mg-HCO₃, Ca-Na-HCO₃, and Na-Ca-HCO₃. Water types of Ca-HCO₃ and Ca-Mg-HCO₃ dominate the upland areas, indicating relatively young groundwater with moderate total dissolved solids (TDSs) and enrichment in δ¹⁸O and δ²H, where highly mineralized Na-HCO₃ water types prevail in the deep aquifers of the lowland regions, where δ¹⁸O and δ²H are relatively depleted. Principal component analysis, cross-plots of major cations versus HCO₃⁻, and mineral stability diagrams indicate that aluminosilicate weathering and dissolution are the dominant processes controlling groundwater chemistry in the study area. The higher saturation index values observed in the deep wells indicate water closer to mineral equilibrium, suggesting more extended water–rock interaction relative to the shallow wells. The CO₂ partial pressures calculated using PHREEQC exceed atmospheric levels (~10^−3.5 atm), indicating sources from atmospheric influx, soil, or biogenic activity for most samples, and deeper sources such as mantle degassing may be found in a few deep wells. Scatter plots of Cl⁻ vs. SO₄²⁻ and Cl⁻ vs. NO₃⁻, associated with Ca(NO3)₂, NaNO₃, and CaCl₂ water types, suggest that anthropogenic inputs are the second major factor influencing the area’s water chemistry. Stable isotope analyses and hydrochemical data indicate that groundwater in the area primarily originates from local precipitation, with isotopic signatures reflecting strong groundwater–surface water interaction. These findings improve understanding of regional hydrogeochemistry and groundwater quality and help identify promising zones for sustainable groundwater development. This study provides valuable insights into groundwater resource management both in the study area and in regions sharing comparable geological contexts. Full article