Search Results (2,267)

The Economic Dispatch Problem (EDP) plays a critical role in power system operations by trying to allocate power generation across multiple units at minimal cost while satisfying complex operational constraints. Traditional optimization techniques struggle with the non-convexities introduced by factors such as valve-point effects, prohibited operating zones, and spinning reserve requirements. While metaheuristics methods have shown promise, they often suffer from convergence issues and constraint-handling limitations. In this study, we introduce a novel application of Group Relative Policy Optimization (GRPO), a reinforcement learning framework that extends Proximal Policy Optimization by integrating group-based learning and relative performance assessments. The proposed GRPO approach incorporates smart initialization, adaptive exploration, and elite-guided updates tailored to the EDP’s structure. Our method consistently produces high-quality, feasible solutions with faster convergence compared to state-of-the-art metaheuristics and learning-based methods. For instance, in the case of the 15-unit system, GRPO achieved the best cost of USD 32,421.67/h with full constraint satisfaction in just 4.24 s, surpassing many previous solutions. The algorithm also demonstrates excellent scalability, generalizability, and stability across larger-scale systems without requiring parameter retuning. These results highlight GRPO’s potential as a robust and efficient tool for real-time energy scheduling in smart grid environments. Full article

A pivotal food crop in arid and semi-arid zones, proso millet boasts remarkable economic value, making the breeding of stable high-yield varieties critical for industrial sustainability. This study employed a randomized complete block design to conduct a two-year multi-environment trial on nine new varieties across six representative spring-sown test regions in China. Analytical tools, including additive main effects and multiplicative interaction (AMMI) biplots, AMMI stability values (ASV), genotype and genotype × environment (GGE) models, and genotype by yield–trait (GYT) biplots were utilized to assess genotype–environment (G × E) interactions and screen superior genotypes. AMMI variance analysis showed extremely significant effects of genotype, environment, and G × E on yield traits (p < 0.01). G × E principal component analysis identified JS8, PS3, PS6, and PM4 as dominant genotypes. Based on ASV indices, varietal stability rankings were PS5 > YS13 > JS8 > PS3 > PS6 > PM4 > others. GGE analysis indicated PM4 had the broadest adaptability across tested environments, while JS15 exhibited specific adaptability in Datong. Huairen and Shuozhou were validated as ideal testing environments via an ideal environment plot. GYT biplots further confirmed that YS13, JS15, PS3, and PM4 excelled in comprehensive yield–trait combinations. These findings offer a scientific foundation for ecological adaptability evaluation, breeding material selection, and commercial variety promotion. Full article

This study investigates the formation mechanism and stress response characteristics of normal faults in coal-bearing strata through large-scale physical simulation experiments. A multi-layer heterogeneous model with a geometric similarity ratio of 1:300 was constructed using similar materials that were tailored to match the mechanical properties of real strata. Real-time monitoring techniques, including fiber Bragg grating strain sensors and a DH3816 static strain system, were employed to record the evolution of deformation, strain, and displacement fields during the fault development. The results show that the normal fault formation process includes five distinct stages: initial compaction, fault initiation, crack propagation, fault slip, and structural stabilization. Quantitatively, the vertical displacement of the hanging wall reached up to 5.6 cm, equivalent to a prototype value of 16.8 m, and peak horizontal stress increments near the fault exceeded 0.07 MPa. The experimental data reveal that stress concentration during the fault slip stage causes severe damage to the upper coal seam roof, with localized vertical stress fluctuations exceeding 35%. Structural planes were found to control crack nucleation and slip paths, conforming to the Mohr–Coulomb shear failure criterion. This research provides new insights into the dynamic coupling of tectonic stress and fault mechanics, offering novel experimental evidence for understanding fault-induced disasters. The findings contribute to the predictive modeling of stress redistribution in fault zones and support safer deep mining practices in structurally complex coalfields, which has potential implications for petroleum geomechanics and energy resource extraction in similar tectonic settings. Full article

Understanding the spatiotemporal dynamics of croplands is crucial for guiding agricultural transformation, food security, and sustainable land use in Africa. This study employs 30 m resolution land cover data and multi-source datasets to examine the spatiotemporal changes in rainfed and irrigated cropland and their driving factors in Tanzania from 1990 to 2020 through multiple GIS spatial analysis methods. The results indicate a net increase in Tanzania’s total cropland area, primarily driven by the expansion of irrigated cropland that has offset the volatile decline of rainfed cropland. From 1990 to 2000, rainfed cropland showed intense bidirectional conversion with shrubland and forest; thereafter, the scale of this conversion continued to decrease. In contrast, irrigated cropland expansion exhibited phased fluctuations. Spatially, rainfed cropland dominates the central, lake, and western zones, while irrigated cropland is predominantly concentrated in the western and southern highland. Hotspots of rainfed cropland shifted from extensive expansion in the central and western zones during the 1990s to localized growth in mountainous areas by the 2010s. Concurrently, irrigated cropland hotspots evolved from a lakeside-concentrated pattern to contiguous development in the central and western zones. Both cropland types exhibit a northwest–southeast spatial orientation. The center of rainfed cropland shifted northwest before moving southeast, while that of irrigated cropland migrated southeastward and then stabilized. Rainfall is a key determinant of rainfed cropland distribution, whereas river network and road network density exert a growing influence on irrigated cropland. Full article

In the mining of deep mineral resources and tunnel engineering, the degradation of mechanical properties and the evolution of energy of through-double-joint sandy slate under triaxial loading and unloading conditions are key scientific issues affecting the stability design of the project. The existing research has insufficiently explored the joint inclination angle effect, damage evolution mechanism, and energy distribution characteristics of this type of rock mass under the path of increasing axial pressure and removing confining pressure. Based on this, in this study, uniaxial compression, conventional triaxial compression and increasing axial pressure, and removing confining pressure tests were conducted on four types of rock-like materials with prefabricated 0°, 30°, 60°, and 90° through-double-joint inclinations under different confining pressures. The axial stress/strain curve, failure characteristics, and energy evolution law were comprehensively analyzed, and damage variables based on dissipated energy were proposed. The test results show that the joint inclination angle significantly affects the bearing capacity of the specimen, and the peak strength shows a trend of first increasing and then decreasing with the increase in the inclination angle. In terms of failure modes, the specimens under conventional triaxial compression exhibit progressive compression/shear failure (accompanied by rock bridge fracture zones), while under increased axial compression and relief of confining pressure, a combined tensioning and shear failure is induced. Moreover, brittleness is more pronounced under high confining pressure, and the joint inclination angle also has a significant control effect on the failure path. In terms of energy, under the same confining pressure, as the joint inclination angle increases, the dissipated energy and total energy of the cemented filling body at the end of triaxial compression first decrease and then increase. The triaxial compression damage constitutive model of jointed rock mass established based on dissipated energy can divide the damage evolution into three stages: initial damage, damage development, and accelerated damage growth. Verified by experimental data, this model can well describe the damage evolution characteristics of rock masses with different joint inclination angles. Moreover, an increase in the joint inclination angle will lead to varying degrees of damage during the loading process of the rock mass. The research results can provide key theoretical support and design basis for the stability assessment of surrounding rock in deep and high-stress plateau tunnels, the optimization of support parameters for jointed rock masses, and early warning of rockburst disasters. Full article

The Chengdu–Chongqing Economic Mega Region (CCEMR), as a strategic economic hub in Western China, is increasingly facing challenges in balancing urban growth, agricultural stability, and ecological conservation within its territorial spatial planning framework. This study addresses the critical need to integrate multidimensional resilience assessment into China’s territorial spatial planning system. A framework for functional resilience assessment was developed through integrated GIS spatial analysis, with three resilience dimensions explicitly aligned to China’s “Three Zones and Three Lines” (referring to urban, agricultural, and ecological space and spatial control lines) territorial planning system: urban resilience was evaluated using KL-TOPSIS ranking, where weights were derived from combined Delphi expert consultation and AHP; agricultural resilience was quantified through the entropy method for weight determination and GIS raster calculation; and ecological resilience was assessed via a Risk–Recovery–Potential (RRP) model integrating Ecosystem Risk, Recovery Capacity (ERC), and Service Value (ESV) metrics, implemented through GIS spatial analysis and raster operations. Significant spatial disparities emerge, with only 1.29% of CCEMR exhibiting high resilience (concentrated in integrated urban–ecological zones like Chengdu). Rural and mountainous areas demonstrate moderate-to-low resilience due to resource constraints, creating misalignments between resilience patterns and current territorial spatial zoning schemes. These findings provide scientific evidence for optimizing the delineation of the Three Major Spatial Patterns: urbanized areas, major agricultural production zones, and ecological functional zones. In this research, a transformative methodology is established for translating resilience diagnostics directly into territorial spatial planning protocols. By bridging functional resilience assessment with statutory zoning systems, this methodology enables the following: (1) data-driven resilience construction for the Three Major Spatial Patterns (urbanized areas, major agricultural production zones, and ecological functional zones); (2) strategic infrastructure prioritization; and (3) enhanced cross-jurisdictional coordination mechanisms. The framework positions spatial planning as a proactive tool for adaptive territorial governance without requiring plan revision. Full article

This study presents the first application of a deep-towed transmitter–receiver marine controlled-source electromagnetic (TTR-MCSEM) system for gas hydrate exploration in the Shenhu area of the South China Sea. High-resolution electromagnetic data were acquired along a 13 km transect using dynamic source–receiver offsets and a 500 A transmitter. The results reveal the following: (1) unprecedented near-seafloor resolution (20~100 m) for the precise delineation of hydrate-bearing caprock, surpassing conventional ocean-bottom electromagnetic systems; (2) laterally continuous high-resistivity anomalies (~10 Ω·m) extending from the base of the gas hydrate stability zone to the seafloor, which correlate with seismic bottom-simulating reflector (BSR) distributions and suggest heterogeneous hydrate saturation; and (3) fault-controlled fluid migration pathways that supply hydrate reservoirs and lead to seabed methane seepage at structural highs. Through 2D inversion, we show that the inverted resistivity values (~10 Ω·m) are slightly higher than those obtained from resistivity logs (~5 Ω·m). Saturation values derived from inverted resistivity exhibit remarkable consistency with well-log-based measurements. The high efficiency of the system confirms its potential for the transformative quantitative assessment of hydrate systems, seafloor massive sulfides, and marine geohazards. Full article

Regenerative chatter is an unfavorable phenomenon that severely affects machining efficiency and surface finish in milling operations. The prediction of chatter stability is an important way to obtain the stable cutting zone. Based on implicit multistep schemes, this paper presents the third-order and fourth-order implicit exponentially fitted methods (3rd IEM and 4th IEM) for milling stability prediction. To begin with, the delay differential equations (DDEs) with time-periodic coefficients are employed to describe the milling dynamics models, and the principal period of the coefficient matrix is firstly decomposed into two different subintervals according to the cutting state. Subsequently, the fourth-step and fifth-step implicit exponential fitting schemes are applied to more accurately estimate the state term. Two benchmark milling models are utilized to illustrate the effectiveness and advantages of the high-order implicit exponentially fitted methods by making comparisons with the three typical existing methods. Under different radial immersion conditions, the numerical results demonstrate that the 3rd IEM and the 4th IEM exhibit both faster convergence rates and higher prediction accuracy than the other three existing prediction methods, without much loss of computational efficiency. Finally, in order to verify the feasibility of the 3rd IEM and the 4th IEM, a series of experimental verifications are conducted using a computer numerical control machining center. It is clearly visible that the stability boundaries predicted by the 3rd IEM and the 4th IEM are mostly consistent with the cutting test results, which indicates that the proposed high-order exponentially fitted methods achieve significantly better prediction performance for actual milling processes. Full article

The abnormal pore pressures in ultra-deep wells in the Junggar Basin, China are constantly causing drilling incidents for both the drilling engineers and geologists. Formation pore-pressure is an important parameter in wellbore stability analysis, and accurate prediction of pore pressure before drilling is of great significance for effectively controlling wellbore instability. In this paper, the authors utilize seismic velocity inversion and rock mechanics prediction to evaluate the three pressure parameters, i.e., pore pressure, collapse pressure, and fracture pressure. Seismic data were inversed and the velocity model was constructed. Then, the layering models of the relationships between seismic velocity and logging data of the whole formation layers were constructed using seismic attributes and the corresponding acoustic logging data. Finally, the acoustic logging data, or interval transit time of ten corresponding formations, were predicted using layering models of seismic data. In an ultra-deep well, two abnormal highly pressurized sections were confirmed. This shows great potential for realizing real-time prediction of acoustic and density log data of undrilled formations in this area. Field applications confirm that the proposed method enhances prediction accuracy and computational efficiency compared to the Eston method. Two abnormal high-pressure zones were successfully identified in the Huqian-1 well, i.e., the Taxihe Formation (1.38 g/cm³) and the Anjihaihe Formation (1.50 g/cm³). Full article

In the context of global climate change, a comprehensive understanding of the spatiotemporal impacts of drought on vegetation productivity is essential for assessing terrestrial ecosystem stability. Utilizing outputs from six global climate models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6), this study systematically assessed historical and projected drought probability, the drought vulnerability of Net Primary Productivity (NPP), and overall drought risk across the Mongolian Plateau under three Shared Socioeconomic Pathway scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5). Results revealed that the Standardized Precipitation Evapotranspiration Index (SPEI) exhibited a declining trend, whereas NPP showed an overall increasing trend. These changes were most pronounced under the SSP5-8.5 scenario, with the SPEI decreasing at a rate of −0.39/10a and NPP increasing at 25.8/10a. Drought severity exhibited strong spatial heterogeneity, intensifying from northeast to southwest, whereas NPP demonstrated an inverse spatial pattern. The spatial distribution of high-drought-risk zones varied markedly across scenarios: the southwestern region was most affected under SSP1-2.6, the northwestern region under SSP2-4.5, and the southeastern region under SSP5-8.5. Based on 12-month SPEI values and NPP derived from the Carnegie–Ames–Stanford Approach (CASA) model, SSP2-4.5 presented the highest overall drought risk, despite lower emissions. The annual mean NPP drought vulnerability ranked as follows: SSP2-4.5 (0.60 $\mathrm{g}\mathrm{C}{\mathrm{m}}^{-2}{\mathrm{y}\mathrm{r}}^{-1}$) > SSP1-2.6 (−1.03 $\mathrm{g}\mathrm{C}{\mathrm{m}}^{-2}{\mathrm{y}\mathrm{r}}^{-1}$) > SSP5-8.5 (−1.24 $\mathrm{g}\mathrm{C}{\mathrm{m}}^{-2}{\mathrm{y}\mathrm{r}}^{-1}$). Projections indicated a substantial increase in drought occurrence probability during the period 2061–2100, particularly under SSP2-4.5 and SSP5-8.5. Under higher emissions, the spatial extent of areas with negative drought vulnerability values was expected to expand 68%. Wind speed was the dominant factor influencing drought risk under SSP1-2.6 and SSP2-4.5, whereas precipitation became the primary driver (45.34%) under SSP5-8.5. These findings offer critical insights for early drought warning systems and for strengthening ecosystem resilience across the Mongolian Plateau. Full article

This study addresses engineering challenges associated with sandy residual deposits in the coastal zone of Quanzhou, China, characterized by high void ratios (e > 0.8), low cohesion (c < 10 kPa), and strong liquefaction tendencies induced by marine dynamic forces. Focusing on the beach sands of Shenhu Bay and Qingshan Bay, 123 in situ dynamic penetration tests and 12 laboratory physical–mechanical tests (including water content, particle gradation, relative density, and triaxial shear strength) were conducted. The correlations between the physical and mechanical properties of these coastal sandy soils and their foundation bearing capacity were systematically analyzed. Results reveal that the sands, predominantly medium-to-fine grains with 8–15% biogenic debris, are generally in a loose-to-medium dense state (relative density ~34%), with negligible cohesion. Shear strength depends primarily on the internal friction angle (28.89–37.43°). Correlation analyses show that water content (17.8–31.92%) and particle gradation parameters (uniformity coefficient C_u and curvature coefficient C_c) significantly influence bearing capacity, with bearing capacity increasing by 12.15% per 14.12% rise in water content and 35% per 0.518 increase in C_c. An improved foundation bearing capacity model based on the Prandtl–Reissner theory is proposed by integrating particle gradation and water content, tailored for beach foundations in Quanzhou. Model validation demonstrates an average error of approximately 15%, outperforming traditional models. These findings provide valuable theoretical support for assessing foundation stability in building construction projects in Quanzhou and similar coastal regions. Full article

This study presents the diagnostics and microclimate analysis of four case studies located in the Alps region in Valtellina and Valposchiavo. The primary focus is on evaluating and comparing microclimatic conditions, encompassing temperature (T°C), relative humidity (RH%), mixing ratio (MR), and dew point depression (DPD). The choice of the variables and statistic metrics depends substantially on the aim to identify the risk factor for the preservation of the historical materials of historical buildings, and the procedures for identifying the anomalies in the trends useful to study how to prevent these anomalies in the future. The paper has the target to support the activities of restorers and building managers for improving the restoration process. While various moisture detection methodologies have been studied, no single approach is preferred for analyzing moisture via microclimate monitoring in built heritage. Therefore, this research delves into the influence of various factors, including altitude, location, building type, structure, materials, orientation, and use, on the microclimatic parameters. Altitude and building use significantly influence indoor microclimates: unoccupied structures exhibit greater stability, whereas seasonal use increases condensation risks. Key risks included high RH% and critical T-RH zones (T > 25 °C + RH > 65%), exacerbating material stress. Probability density function (PDF) analysis reveals temperature and RH% distributions, highlighting bimodal T°C patterns and prolonged RH% in high-elevation exposed sites. The findings underscore the need for tailored conservation strategies and targeted interventions to mitigate microclimate-induced deterioration in Alpine heritage. Full article

The affordability, ease of manufacturing, and assembly efficiency of cold-formed steel profiles have contributed to their widespread use in structural applications. However, the presence of holes in these profile webs is likely to reduce their mechanical resistance. This study explores the bending behavior of a built-up box section constructed using lipped and unlipped C-profiles, which are commonly utilized in the construction industry. The investigation focuses on the influence of self-drilling screw layout density and hole distribution within the section. A total of 30 different models were analyzed, considering three primary variables: the spacing of self-drilling screws, hole diameter, and the number of holes. The steel profiles were connected using self-drilling screws with spacing intervals of 100, 200, and 400 mm. Key parameters, such as moment capacity, effects on elastic zones, shear forces on screws, and ductility, were examined in relation to these variables. The findings indicate that reducing screw spacing and increasing the number of holes are crucial design factors for improving joint strength. However, while greater screw spacing enhances ductility, it leads to lower plastic deformation rates. Additionally, optimizing the number of holes in the section proved to be an effective strategy for improving ductility in the analyzed models. Mathematical evaluation confirmed that hole number and screw spacing significantly affect moment capacity and estimation stability, highlighting the need for their joint optimization in structural design. Full article

The seismic bearing capacity of water-saturated composite foundations adjacent to slopes is critical for engineering safety, yet it is significantly influenced by complex factors such as earthquakes and heavy rainfall. This paper establishes a failure mechanism model that involves both reinforced and non-reinforced zones, comprehensively considering the synergistic effects of seismic force, pore water pressure and group pile replacement rate, and thus addressing the issue that existing models struggle to account for the coupling effects of multiple factors. Based on the principle of virtual work, a general solution for ultimate bearing capacity is derived, and the optimal solution is obtained using the MATLAB R2023a exhaustive method. Findings reveal that pile group support substantially enhances bearing capacity: the improvement becomes more pronounced with higher soil strength parameters (φ, c) and replacement ratios. When the seismic acceleration coefficient increases from 0 to 0.3, the bearing capacity of the unreinforced foundation decreases by approximately 61.6% (from 134.71 kPa to 51.83 kPa), while group pile support can increase the bearing capacity by 433.2%. Notably, when soil strength is inherently high, the marginal benefit of pile group reinforcement diminishes. A case study in Fuzhou validates through numerical simulation that pile groups improve foundation stability by altering energy dissipation distribution, with the discrepancy between theoretical calculations and simulation results within 10%. The research results can directly guide the design of saturated composite foundations near slopes in earthquake-prone areas (such as Fujian and Guangdong) and enhance the seismic safety reserve by optimizing the replacement rate of group piles (recommended to be 0.2~0.3). Full article

The rapid development of transportation infrastructure in mountainous terrains, soft-soil foundations, and high-fill embankments poses stability challenges for conventional embankments, driving the application of advanced three-dimensional reinforced soil technologies. Geogrid with Strengthened Nodes (GSN) is one such innovation, forming a three-dimensional structure by placing block-shaped nodes at geogrid rib intersections. Current research on GSN focuses mainly on pullout tests and numerical simulations, while model-scale studies of its load-bearing deformation behavior and soil pressure distribution remain scarce. This study presents laboratory model tests to assess the reinforcement performance of GSN-reinforced embankments under static and dynamic strip loads. Under static loading, the ultimate bearing capacity of GSN-reinforced embankments increased by 74.58% compared with unreinforced cases and by 26.2% compared with conventional geogrids. Under dynamic loading, cumulative settlement decreased by 32.82%, and lateral displacement at the slope crest was reduced by 64.34%. The strengthened node design improved soil shear strength and controlled lateral deformation via enhanced lateral resistance, creating a more stable “reinforced zone” that alleviated local stress concentrations. Overall, GSN significantly enhanced embankment bearing capacity and stability, outperforming traditional geogrid reinforcement under both static and dynamic conditions, and providing a promising solution for challenging geotechnical environments. Full article