Search Results (751)

Accurate and energy-efficient localization of autonomous underwater vehicles (AUVs) remains a fundamental challenge due to the complex, bandwidth-limited, and highly dynamic nature of underwater acoustic environments. This paper proposes a fully adaptive deep reinforcement learning (DRL)-driven localization framework for AUVs operating in Underwater Acoustic Sensor Networks (UAWSNs). The localization problem is formulated as a Markov Decision Process (MDP) in which an intelligent agent jointly optimizes beacon selection and transmit power allocation to minimize long-term localization error and energy consumption. A hierarchical learning architecture is developed by integrating four actor–critic algorithms, which are (i) Twin Delayed Deep Deterministic Policy Gradient (TD3), (ii) Soft Actor–Critic (SAC), (iii) Multi-Agent Deep Deterministic Policy Gradient (MADDPG), and (iv) Distributed DDPG (D2DPG), enabling robust learning under non-stationary channels, cooperative multi-AUV scenarios, and large-scale deployments. A round-trip time (RTT)-based geometric localization model incorporating a depth-dependent sound speed gradient is employed to accurately capture realistic underwater acoustic propagation effects. A multi-objective reward function jointly balances localization accuracy, energy efficiency, and ranging reliability through a risk-aware metric. Furthermore, the Cramér–Rao Lower Bound (CRLB) is derived to characterize the theoretical performance limits, and a comprehensive complexity analysis is performed to demonstrate the scalability of the proposed framework. Extensive Monte Carlo simulations show that the proposed DRL-based methods achieve significantly lower localization error, lower energy consumption, faster convergence, and higher overall system utility than classical TD3. These results confirm the effectiveness and robustness of DRL for next-generation adaptive underwater localization systems. Full article

To address the depletion of shallow coal resources, mining activities have progressed to greater depths, where rock masses contain numerous fractures due to complex geological conditions, making grouting reinforcement essential for ensuring stability. Using digital image correlation, this study investigated the strain evolution characteristics of grouted fractured specimens of three rock types—mudstone, coal–rock, and sandstone—under uniaxial compression. Analysis of the strain evolution process focused on two typical fracture inclinations of 0° and 60°, while examination of the peak strain characteristics covered five inclinations, namely 0°, 15°, 30°, 45°, and 60°. The findings indicate that the mechanical response varies systematically with lithology and fracture inclination. The post-peak curves differ significantly among rock types: coal–rock shows a gentle descent, mudstone exhibits a rapid strength drop but higher residual strength, and sandstone is characterized by “serrated” fluctuations. The failure mode transitions from tensile splitting at a horizontal inclination of 0° to shear failure at inclinations of 15°, 30°, 45°, and 60°. Strain nephograms corresponding to the peak stress point D reveal sharp, band-shaped zones of strain localization. The maximum principal strain exhibits a non-monotonic trend, first increasing and then decreasing with increasing inclination angle. For grouted coal–rock and sandstone, the peak values of 47.47 and 45.00 occur at α = 45°. In contrast, grouted mudstone reaches a maximum value of 26.80 at α = 30°, indicating its lower susceptibility to damage. The study systematically clarifies the strain evolution behavior of grouted fractured rock masses, providing a theoretical basis for evaluating the effectiveness of reinforcement and predicting failure mechanisms. Crucially, the findings highlight mudstone’s role as a high-integrity medium and the particular vulnerability of horizontal fractures, offering direct guidance for the targeted grouting design in stratified rock formations. Full article

As a cornerstone of China’s energy infrastructure, the coal mining industry relies heavily on the stability of its underground roadways, where the support of soft rock formations presents a critical and persistent technological challenge. This challenge arises primarily from the high content of expansive clay minerals and well-developed micro-fractures within soft rock, which collectively undermine the effectiveness of conventional support methods. To address the soft rock control problem in China’s Longdong Mining Area, an integrated material–structure control approach is developed and validated in this study. Based on the engineering context of the 3205 material gateway in Xin’an Coal Mine, the research employs a combined methodology of micro-mesoscopic characterization (SEM, XRD), theoretical analysis, and field testing. The results identify the intrinsic instability mechanism, which stems from micron-scale fractures (0.89–20.41 μm) and a high clay mineral content (kaolinite and illite totaling 58.1%) that promote water infiltration, swelling, and strength degradation. In response, a novel synergistic technology was developed, featuring a high-performance grouting material modified with redispersible latex powder and a tiered thick anchoring system. This technology achieves microscale fracture sealing and self-stress cementation while constructing a continuous macroscopic load-bearing structure. Field verification confirms its superior performance: roof subsidence and rib convergence in the test section were reduced to approximately 10 mm and 52 mm, respectively, with grouting effectively sealing fractures to depths of 1.71–3.92 m, as validated by multi-parameter monitoring. By integrating microscale material modification with macroscale structural optimization, this study provides a systematic and replicable solution for enhancing the stability of soft rock roadways under demanding geo-environmental conditions. Soft rock roadways, due to their characteristics of being rich in expansive clay minerals and having well-developed microfractures, make traditional support difficult to ensure roadway stability, so there is an urgent need to develop new active control technologies. This paper takes the 3205 Material Drift in Xin’an Coal Mine as the engineering background and adopts an integrated method combining micro-mesoscopic experiments, theoretical analysis, and field tests. The soft rock instability mechanism is revealed through micro-mesoscopic experiments; a high-performance grouting material added with redispersible latex powder is developed, and a “material–structure” synergistic tiered thick anchoring reinforced load-bearing technology is proposed; the technical effectiveness is verified through roadway surface displacement monitoring, anchor cable axial force monitoring, and borehole televiewer. The study found that micron-scale fractures of 0.89–20.41 μm develop inside the soft rock, and the total content of kaolinite and illite reaches 58.1%, which is the intrinsic root cause of macroscopic instability. In the test area of the new support scheme, the roof subsidence is about 10 mm and the rib convergence is about 52 mm, which are significantly reduced compared with traditional support; grouting effectively seals rock mass fractures in the range of 1.71–3.92 m. This synergistic control technology achieves systematic control from micro-mesoscopic improvement to macroscopic stability by actively modifying the surrounding rock and optimizing the support structure, significantly improving the stability of soft rock roadways. Full article

Seasonal groundwater rise of 2.5–3.0 m leads to full saturation of the lakeside slope of the railway embankment, significantly reducing the strength of clayey–sandy loam layers. Laboratory shear tests showed that saturation decreases the internal friction angle from 24–26° to 16–19°, while effective cohesion drops from 12–18 kPa to 0–3 kPa, identifying the 3–6 m depth interval as the critical weak zone. These parameters were incorporated into PLAXIS 2D/3D hydro-mechanical models to assess the embankment behaviour under three scenarios: natural conditions, high water level, and reinforced configuration. Under elevated water levels, lateral displacement toward the lakeside increased to 0.16–0.21 m, and the plastic strain zone expanded by a factor of 2.4, reducing the safety factor from FS ≈ 1.32 to below 1.10. The proposed stabilization system—replacement of a 1.5 m weak layer, installation of geotextile reinforcement, and application of a bituminous waterproofing layer—substantially improved stability, reducing maximum lateral displacement to 0.12 m (≈43% reduction) and restoring the safety factor to FS = 1.25–1.40. The results demonstrate that low-cost geosynthetic barriers provide an effective and practical engineering solution for maintaining the long-term stability of railway embankments exposed to seasonal inundation. Full article

This work presents a hierarchical deep reinforcement learning (DRL) framework based on Soft Actor–Critic (SAC) for the autonomy of rock-breaking machinery in surface mining comminution processes. The proposed approach explicitly integrates mobile navigation and hydraulic manipulation as coupled subprocesses within a unified decision-making architecture, designed to operate under the unstructured and highly uncertain conditions characteristic of open-pit mining operations. The system employs a hysteresis-based switching mechanism between specialized SAC subagents, incorporating automatic entropy tuning to balance exploration and exploitation, twin critics to mitigate value overestimation, and curriculum learning to manage the progressive complexity of the task. Two coupled subsystems are considered, namely: (i) a tracked mobile machine with a differential drive, whose continuous control enables safe navigation, and (ii) a hydraulic manipulator equipped with an impact hammer, responsible for the fragmentation and dismantling of rock piles through continuous joint torque actuation. Environmental perception is modeled using processed perceptual variables obtained from point clouds generated by an overhead depth camera, complemented with state variables of the machinery. System performance is evaluated in unstructured and uncertain simulated environments using process-oriented metrics, including operational safety, task effectiveness, control smoothness, and energy consumption. The results show that the proposed framework yields robust, stable policies that achieve superior overall process performance compared to equivalent hierarchical configurations and ablation variants, thereby supporting its potential applicability to DRL-based mining automation systems. Full article

Magnesium matrix composites formed by incorporating ceramic particles into a magnesium alloy matrix can effectively leverage the complementary properties of the matrix and reinforcement. This approach significantly enhances the mechanical properties of the material at both room and elevated temperatures, offering a viable solution to the inherent limitations of Mg alloys, such as insufficient absolute strength, stiffness, and poor heat resistance. This article reviews the latest research progress in the field of ceramic particle-reinforced magnesium matrix composites in recent years. First, the current research status of magnesium matrix composites reinforced with different types of ceramic particles is comprehensively summarized. Subsequently, it provides a summary and in-depth analysis of the principles, key technologies, and microstructural characteristics of both mainstream and emerging preparation processes, and discusses their advantages and disadvantages. Finally, the challenges in current research are analyzed, and future cutting-edge directions for developing high-performance ceramic particle-reinforced magnesium matrix composites are discussed. Full article

With the continuous increase in well depth and the gradual depletion of formation energy, the pump-setting depths in rod-pumped wells have increased significantly, leading to higher suspension loads at the pumping unit. The application of glass fiber-reinforced plastic (FRP) sucker rods can effectively reduce suspension loads due to their low density and high tensile strength. However, the mechanical performance of FRP rods is highly sensitive to temperature, which poses challenges for their application in deep and high-temperature wells. In FRP–steel hybrid sucker-rod string design, the influence of temperature—particularly on FRP rods—must therefore be carefully considered to prevent failures such as rod parting or coupling separation. This study systematically investigates the effects of temperature on the mechanical properties of FRP sucker rods, including elastic modulus, flexural shear strength, and tensile strength. Based on the operating characteristics of sucker-rod pumping systems and established design criteria, a temperature-aware design methodology for FRP–steel hybrid rod strings is developed and implemented in dedicated design software. The proposed approach enables rational determination of the FRP–steel partition depth under thermal constraints while satisfying mechanical safety requirements. A field case study is conducted to validate the design results, demonstrating that the software provides reliable and practical guidance for hybrid rod-string design in deep wells. Full article

Some expressway emergency lanes adopt simplified pavement structures that fail to meet load-bearing requirements after reconstruction. To address the issue of subgrade reinforcement without excavation, a finite element method was employed to analyze the effects of enlarged-borehole grouting (EBG), considering variations in grouting depth and inter-pile subgrade modulus, on pavement load-bearing capacity. Furthermore, field experiments were conducted to evaluate grouting techniques, including enlarged-borehole micro-expansive cement casting (EB-MECC) and enlarged-borehole steel flower pipe split grouting (EB-SFPSG), and three composite grouting schemes. Results indicated that EBG effectively improved the fatigue cracking life of the semi-rigid base layer. Reinforcement effectiveness was positively correlated with grouting depth and subgrade modulus, with the latter exhibiting a more significant influence. Therefore, a 1.5 m grouting depth combined with splitting or compaction is recommended to enhance subgrade stiffness. Field experiments showed that EB-SFPSG effectively enhanced pile–subgrade interaction and mitigated stress concentration around the pile–pavement interface. Comparison of the three composite grouting schemes revealed that both the scheme employing only EB-SFPSG and the hybrid scheme using EB-SFPSG in the middle row with EB-MECC in the side rows exhibited favorable mechanical performance. The latter, however, was achieved at a lower construction cost. Another hybrid scheme that further replaced the middle row with enlarged-borehole conventional pressure grouting (EB-CPG) provided limited reinforcement and poorer uniformity. Full article

The Turkish steel industry aims to reduce its sectoral carbon dioxide (CO₂) emissions by 55% by 2030, in line with Türkiye’s Paris Agreement commitments and the European Green Deal (EGD), and consistent with the ambition of the European Union’s economy-wide ‘Fit for 55’ emissions-reduction target. Türkiye faces significant challenges in achieving net-zero greenhouse gas (GHG) emissions, particularly as a developing country confronting the impacts of climate change and in the market situation, such as the effects of the ongoing Russia-Ukraine conflict, limited access to affordable raw materials, and rising operational costs. This study serves as a guideline for the Turkish steel sector’s roadmap towards modernization and eventual compliance with net-zero targets. The consideration and integration of new technologies planned for the Turkish steel industry, in both electric arc furnace (EAF) and blast furnace-basic oxygen furnace (BF-BOF) facilities, have been outlined in conjunction with green hydrogen and with Carbon Capture and Storage (CCS) technologies. Four different scenarios were analysed to understand the reduction in CO₂ emissions: (1) In a Business-As-Usual (BAU) scenario without any reduction, (2) 39.9% CO₂ emission reduction with the Moderate scenario, (3) 59.6% reduction with the Advanced scenario, and (4) 82.9% reduction in CO₂ emissions from the Turkish steel sector with the Net-Zero scenario. To quantify the uncertainty in these long-term projections, a Monte Carlo simulation was conducted, generating probabilistic confidence intervals that reinforce the robustness and credibility of the net-zero pathway. The official roadmap for the sector is not available as of today; however, an in-depth discussion with a policy innovation leading to it is the objective of this study. Full article

To investigate the fracture behavior of super-absorbent polymer (SAP) internally cured polyvinyl alcohol (PVA) fiber-reinforced concrete (SAP-PVAC), three-point bending tests were carried out. This study systematically examined the effects of (1) PVA fiber content and (2) initial crack-depth-to-beam-height ratios (a₀/D) on the failure modes, fracture toughness (K_IC), and residual flexural tensile strength (f_R,1) of SAP-PVAC beams. The test results demonstrate that SAP particles have a weakening effect on concrete strength (reduce about 6%). Still, the addition of PVA fibers can effectively improve the crack-resistance performance of SAP-PVAC and significantly increase the residual flexural tensile strength by 4.5–42%. The softening performance of the concrete is affected by the initial crack-height ratio. An increase in a₀/D leads to an obvious increase in the crack opening displacement but has little impact on the fracture toughness, while the fracture energy shows a downward trend. SEM microscopic analysis reveals that the synergistic effect of SAP and PVA fibers exhibits a positive promoting effect on the toughening and crack resistance of SAP-PVAC specimens. These results establish a theoretical framework for SAP-PVAC fracture assessment and provide actionable guidelines for its shrinkage-crack mitigation structure engineering applications. Full article

Conventional drilling pressure relief technology destroys the rock integrity of the roadway-surrounding rock and support system in the anchorage area of surrounding rock at the same time as roadway pressure relief. To overcome the incompatibility between roadway pressure relief and structural support, an integrated control strategy combining anchorage reinforcement with pressure release was established. The distribution characteristics of the deviatoric stress field under different internal borehole parameters were investigated through numerical simulations, and the influence degree of each parameter is discussed. We constructed a similar model to verify the reasonable key parameters of pressure relief and evaluate the pressure relief effect. The conclusions drawn are as follows. (1) The sensitivity ranking of factors affecting pressure relief in the surrounding rock was determined as internal hole-making position > internal hole-making length > internal hole-making spacing. At an internal hole-making depth of 10 m, the peak deviatoric stress migrated to deeper regions, accompanied by a notable reduction in its distribution range. Hence, the stress within the roadway-surrounding rock was effectively released. (2) The internal deviatoric stress peak (si) and its corresponding location were identified according to the internal borehole-creation position. As the internal hole-making length increased, the positional transfer effect became notably stronger. Appropriately extending the internal hole-making length can thus create a compensatory buffer zone that accommodates the volumetric expansion deformation of the roadway sides. (3) By appropriately determining the position and length of the internal boreholes, reducing the spacing between them can substantially release high deviatoric stress. When the spacing was ≤4 m, the rock surrounding the borehole exhibited a low-deviatoric-stress state, suggesting that the deviatoric stress between adjacent internal holes was largely dissipated without elevating the stress level in the shallow surrounding rock. (4) A comparable simulation approach confirmed the feasibility of implementing internal hole-making and pressure relief measures on both sides of a deep coal roadway. Field engineering applications further demonstrated that the proposed “anchorage + pressure relief” cooperative control system can effectively restrain the continuous large deformation of the surrounding rock along the sidewalls in soft and fractured deep chambers. These findings offer an effective strategy for controlling large-scale deformation and failure of surrounding rock in similar deep roadways and provide valuable engineering insights. Full article

The hydraulic performance of woven geotextiles is frequently overlooked in roadway design, despite their extensive use for reinforcement applications. Woven geotextiles are typically manufactured from hydrophobic polymers such as polypropylene or polyester and can act as capillary barriers under unsaturated conditions. This results in moisture accumulation at the soil–geotextile interface, adversely impacting long-term pavement performance. Such problems can be effectively mitigated using geotextiles with enhanced lateral drainage (ELD) capabilities, which are engineered with hydrophilic fibers to facilitate capillary-driven lateral water movement under unsaturated conditions. This functionality facilitates the redistribution of moisture away from the interface, mitigating moisture retention and enhancing drainage performance. The hydraulic performance of geotextiles with enhanced lateral drainage capabilities under unsaturated conditions remains insufficiently understood, particularly in terms of their influence zone and drainage efficiency. For this reason, the present study evaluates the lateral drainage behavior of an ELD geotextile using a soil column test, compared against a control setup without a geotextile and with a non-woven geotextile. Two moisture migration scenarios, namely capillary rise and vertical infiltration, were simulated, with the water table varied at multiple depths. Moisture sensors were embedded along the column depth to monitor real-time water content variations. Results show that the ELD geotextile facilitated efficient lateral drainage, with a consistent influence zone extending up to 2 inches below the fabric. Under infiltration, the ELD geotextile reduced moisture accumulation by 30% around the geotextile, highlighting its superior drainage behavior. These findings encourage practicing engineers to adopt rational, performance-based designs that leverage ELD geotextiles to enhance subgrade drainage and moisture control in pavement and geotechnical applications. Full article

Short dry spells during the rainy season have become increasingly common in Brazil, reinforcing the need for soil water conservation practices. Plastic mulching can enhance plant water use and mitigate abiotic stress. This study evaluates water use efficiency in terms of soil physical quality, root systems, and photosynthetic performance of citrus plants grown in different Inceptisols. The field experiment, in a randomized block design with a split-plot arrangement, was conducted in Lavras, Brazil, and involved citrus (orange) plants from 2012 to 2014. Undisturbed soil samples were collected at depths of 0.00–0.05, 0.20–0.25, and 0.90–0.95 m, two years after the installation of white plastic (WP), black plastic (BP), and no plastic (NP) mulching treatments in two Inceptisol types, totaling 54 samples. The soil water-retention curve, pore size distribution, and soil physical quality indicators were determined, and root system distribution maps were generated using B-splines. Leaf gas exchange was measured under contrasting precipitation conditions. Inceptisol I showed minimal impact from mulching, except for the bulk density and total porosity, which positively correlated with transpiration under BP. In contrast, in Inceptisol II, WP increased photosynthetic rates under low- and high-precipitation conditions but reduced water use efficiency, correlating positively with macropores and negatively with micropores. Plastic mulching reduces physiological stress in citrus and improves soil physical quality, with WP being the most effective across precipitation levels, particularly in less stable soils. Full article

This study numerically investigates pavement damage caused by explosions in buried leaking natural gas pipelines using a coupled Lagrangian–Eulerian (CLE) framework in LS-DYNA. The gas phase is described by a Jones–Wilkins–Lee-based equation of state, while soil and pavement are modeled using a pressure-dependent soil model and the Riedel–Hiermaier–Thoma concrete model with strain-based erosion, respectively. The approach is validated against benchmark underground explosion tests in sand and blast tests on reinforced concrete slabs, demonstrating accurate prediction of pressure histories, ejecta evolution, and crater or damage patterns. Parametric analyses are then conducted for different leaked gas masses and pipeline burial depths to quantify shock transmission, soil heave, pavement deflection, and damage evolution. The results indicate that the dynamic response of the pavement structure is most pronounced directly above the detonation point and intensifies significantly with increasing total leaked gas mass. For a total leaked gas mass of 36 kg, the maximum vertical deflection, the peak kinetic energy, and the peak pressure at the bottom interface at this location reach 148.46 mm, 14.64 kJ, and 10.82 MPa, respectively. Moreover, a deflection-based index is introduced to classify pavement response into slight (<20 mm), moderate (20–40 mm), severe (40–80 mm), and collapse (>80 mm) states, and empirical curves are derived to predict damage level from leakage mass and burial depth. Finally, the effectiveness of carbon fiber reinforced polymer (CFRP) strengthening schemes is assessed, showing that top and bottom surface reinforcement with a total CFRP thickness of 2.67 mm could reduce vertical deflection by up to 37.93% and significantly mitigates longitudinal cracking. The results provide a rational basis for safety assessment and blast resistant design of pavement structures above buried gas pipelines. Full article

Debris flow is a common geological disaster in mountainous areas, characterized by its sudden onset, frequent occurrence, and high destructive power. Retaining dams are one of the most commonly used measures for debris flow prevention and are widely applied in debris flow management projects. This study investigates the impact resistance of retaining dams in high-altitude cold regions by establishing a three-dimensional numerical model of the retaining dam. The results show that the impact depth, resultant impact force, and acceleration of the prestressed reinforced concrete retaining dam with embedded prestressed reinforcement are significantly lower than those of the concrete retaining dam. The prestressed reinforced concrete retaining dam with embedded prestressed reinforcement can improve its impact resistance, effectively mitigating the impact of debris flow block collisions. The impact depth and resultant impact force of the prestressed reinforced concrete retaining dam both increase with the steel ball’s impact speed, impact angle, and impact mass, while they decrease with an increase in the shape coefficient of the steel ball. The effects of different parameters of the steel ball on the impact depth and resultant impact force of the barrier vary. The research findings provide a scientific basis for the design of barriers in the prevention and control of debris flows in high-altitude cold regions. Full article