Pantana phyllostachysae Chao ( P. phyllostachysae ) is a destructive leaf-eating pest that poses a significant threat to the health of bamboo forests and the bamboo industry. However, the spatial and temporal spread mechanisms of this pest are still unclear. To better understand and predict the spread of this pest, we used Sentinel-2A/B images from the pest detection period of 2018 to 2021, to identify association factors from five dimensions, including forest stand, meteorology, topography, pest sources, and human environment factors. The association factor sets for the spread of P. phyllostachysae were established under both existence and non-existence pest control scenarios. The extreme gradient boosting (XGBoost) model was employed to derive conversion rules for the respective spread models, enabling the determination of suitability probabilities for both healthy and damaged bamboo forests. These probabilities were then utilized in conjunction with cellular automata (CA) to simulate the spread of P. phyllostachysae under two scenarios. The results showed that the OA and Kappa reached more than 85% and 0.7 in both scenarios, respectively. Meanwhile, the division of pest control scenarios and the selection of XGBoost both help to improve the spreading simulation accuracy. Our models effectively coupled the research results of leaf hosts of different damage levels, simulated the spread of P. phyllostachysae , and identified the dynamic mechanisms of the pest's spread. These findings provide decision support for interrupting the spread path of the pest and achieving precise control, thus safeguarding forest ecological security.
Fluid occurrence and pore structure are prerequisites for exploring the enrichment pattern of shale oil. The Cretaceous Tengger Formation in the A'nan Sag, Erlian Basin, China, contains abundant shale oil resources. In this study, a series of NMR T2 and T1–T2, combined with Rock-Eval, scanning electron microscopy (SEM), and low-temperature nitrogen adsorption–desorption (LTNA/D), were conducted to clarify the fluid occurrence and pore structure characteristics of the shale oil reservoirs. Meanwhile, the influences of the pore structure on fluid occurrence were discussed. Results suggest that the in situ occurrences and distributions of pore water and oil can be well analyzed by the NMR T1–T2 technique combined with water and oil restorations. The selected shales are characterized by high contents of capillary-bound water and bound oil, and bound oil mainly contributes to shale oil, followed by adsorbed and movable oil. The shales at the as-received state have lost half of the capillary-bound water, as well as most of the bound and movable oil, while adsorbed oil is less affected. The pore spaces primarily consist of interparticle pores related to brittle granules, followed by intraparticle pores in clay mineral aggregates. The T2 spectra are characterized by the dominant peak p2 ranging from 0.7 to 20 ms, corresponding to the developed mesopores (100–1000 nm). Fluid occurrence is closely related to pore structures. Capillary-bound water primarily occurs in micropores (<25 nm) and minipores (25–100 nm) and coexists with adsorbed oil. Mesopores and macropores (>1000 nm) are mainly saturated with bound and movable oil, respectively. The developed large pores generally correspond to less capillary-bound water but more shale oil, especially bound and movable oil. These findings may improve the understanding of enrichment mechanisms of shale oil and provide the references for sweet spot exploitation in the A'nan Sag, Erlian Basin.
Tobacco is a critical cash crop in China, so its growing status has received more and more attention. How to acquire accurate plant area, row spacing, and plant spacing at the same time have been key points for its grow status monitoring and yield prediction. However, accurately detecting small and densely arranged tobacco plants during the rosette stage poses a significant challenge. In Sichuan Province, the contours of scattered tobacco fields with different shapes are not well-extracted. Additionally, there is a lack of simultaneous methods for extracting crucial tobacco planting information, including area, row spacing, and plant spacing. In view of the above scientific problems, we proposed a method to extract the planting information of tobacco at the rosette stage with Unmanned Aerial Vehicle (UAV) remote sensing images. A detection model, YOLOv8s-EFF, was constructed for the small and weak tobacco in the rosette stage. We proposed an extraction algorithm for tobacco field area based on extended contours for different-shaped fields. Meanwhile, a planting distance extraction algorithm based on tobacco coordinates was presented. Further, four experimental areas were selected in Sichuan Province, and image processing and sample label production were carried out. Four isolated tobacco fields with different shapes in four experimental areas were used to preliminarily verify the effectiveness of the model and algorithm proposed. The results show that the precision ranges of tobacco field area, row spacing, and plant spacing were 96.51~99.04%, 90.08~99.74%, and 94.69~99.15%, respectively. And another two experimental areas, Jiange County, Guangyuan, and Dazhai County, Gulin County, and Luzhou, were selected to evaluate the accuracy of the method proposed in the research in practical application. The results indicate that the average accuracy of tobacco field area, row spacing, and plant spacing extracted by this method reached 97.99%, 97.98%, and 98.31%, respectively, which proved the extraction method of plant information is valuable.
In this study, theoretical analysis and numerical simulation methods were used to investigate the mechanical mechanism of the migration failure of the overlying strata and the development characteristics of the water-conducting fractured zone (WCFZ) in the mountainous carbonate areas in southwestern China. Due to the block-shaped rock mass structure characteristics of carbonate rocks, this paper considered the rock mass structure of the overlying strata. For the three-hinged arch structure of the block-shaped rock mass, the theory of damage mechanics was used to deduct the recursive calculation formula for the ultimate subsidence of the three-hinged arch structure of the overlying strata. Then, a method for determining the height of the WCFZ (HWCFZ) in the overlying strata under mining conditions was developed. Numerical simulations were carried out to study the stress field, plastic zone, and displacement field of the overlying strata and the dynamic evolution of the WCFZ during the mining process , and it was revealed that there was a positive feedback effect between them. After the mine was mined, due to the change of the stress field of the overlying strata, the overlying strata were mainly subjected to three types of plastic deformation during the fracturing process: tension, shearing, and tensile-shearing. There was a plastic partitioning phenomenon in the overlying strata. Among them, the tensile-slip failure zone was the most severely damaged. And the boundary of the WCFZ and the bending subsidence zone were determined based on the change characteristics of the displacement field. The HWCFZ obtained from the numerical simulations was consistent with the theoretical calculated value (93 vs. 92.5 m), validating the reliability and accuracy of the theoretical calculation method. Underground mining activities are active in the mountainous carbonate areas in southwestern China, and there are many landslide disasters due to overlying strata collapse, resulting in serious casualties. Therefore, prediction of HWCFZ and stability analysis of mountain need to be carried out for different mines in order to effectively carry out geological disaster prevention and mitigation research.
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