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Cultivated land is the foundation of food security, while coal guarantees the security of the energy. The coal-cropland overlapped area accounts for approximate 42.7% of the total cultivated land area in China, making it become a prominent contradiction between the extensive mining and cultivated land protection. How to realize the coordinated development of the coal mining and the cultivated land protection is an urgent problem in coal-cropland overlapped areas. This paper analyzes the research status and existing issues of the coordinated development between mining and cultivated land protection from the following three aspects: the damage mechanism of subsidence land in plain coal-cropland overlapped areas, the damage degree evaluation of subsidence land induced by mining, the control technology for the mining subsidence. Then, considering the characteristics of the cultivated land, such as the extensive protection-needed area and the high deformation tolerance, a new technical approach of controlling regional rock strata and surface deformation in green mining is proposed by combining source control and restoration. The corresponding prediction and control design methods of surface deformation are established. Additionally, the key research directions for the coordination of coal mining and cultivated land protection in the plain coal-cropland overlapped areas are pointed out, including the driving mechanism of cultivated land damage induced by mining in the plain area, protection thresholds for the quality of the cultivated land in subsidence areas, theories and methods of the subsidence coordinated control of the green mining facing the cultivated land protection. The main objective of this paper is to promote the coordinated development of the green mining and the cultivated land protection in the plain coal-cropland overlapped areas.

Underground coal mining induces surface subsidence, leading to disasters such as damage to buildings and infrastructure, landslides, and surface water accumulation. Preventing and controlling disasters in subsidence areas and reutilizing land depend on understanding subsidence regularity and obtaining surface subsidence monitoring data. These data are crucial for the reutilization of regional land resources and disaster prevention and control. Subsidence hazards are also a key constraint to mine development. Recently, with the rapid advancement of UAV technology, the use of UAV photogrammetry for surface subsidence monitoring has become a significant trend in this field. The periodic imagery data quickly acquired by UAV are used to construct DEM through point cloud filtering. Then, surface subsidence information is obtained by differencing DEM from different periods. However, due to the accuracy limitations inherent in UAV photogrammetry, the subsidence data obtained through this method are characterized by errors, making it challenging to achieve high-precision ground surface subsidence monitoring. Therefore, this paper proposes a spatial domain filtering algorithm for UAV photogrammetry combined with surface deformation caused by coal mining based on the surface subsidence induced by coal mining and combined with the characteristics of the surface change. This algorithm significantly reduces random error in the differential DEM, achieving high-precision ground subsidence monitoring using UAV. Simulation and field test results show that the surface subsidence elevation errors obtained in the simulation tests are reduced by more than 50% compared to conventional methods. In field tests, this method reduced surface subsidence elevation errors by 39%. The monitoring error for surface subsidence was as low as 8 mm compared to leveling survey data. This method offers a new technical pathway for high-precision surface subsidence monitoring in mining areas using UAV photogrammetry. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar (SAR) technology has become an important means of flood monitoring because of its large coverage, repeated observation, and all-weather and all-time working capabilities. The commonly used thresholding and change detection methods in emergency monitoring can quickly and simply detect floods. However, these methods still have some problems: (1) thresholding methods are easily affected by low backscattering regions and speckle noise; (2) changes from multi-temporal information include urban renewal and seasonal variation, reducing the precision of flood monitoring. To solve these problems, this paper presents a new flood mapping framework that combines semi-automatic thresholding and change detection. First, multiple lines across land and water are drawn manually, and their local optimal thresholds are calculated automatically along these lines from two ends towards the middle. Using the average of these thresholds, the low backscattering regions are extracted to generate a preliminary inundation map. Then, the neighborhood-based change detection method combined with entropy thresholding is adopted to detect the changed areas. Finally, pixels in both the low backscattering regions and the changed regions are marked as inundated terrain. Two flood datasets, one from Sentinel-1 in the Wharfe and Ouse River basin and another from GF-3 in Chaohu are chosen to verify the effectiveness and practicality of the proposed method. [ABSTRACT FROM AUTHOR]

Background: The use of the apparent transverse relaxation rate (R2*) in nasopharyngeal carcinoma (NPC) has not been previously reported in the literature. The aim of this study was to investigate the role of the R2* value in evaluating response to concurrent chemoradiotherapy (CCRT) in patients with NPC. Methods: Forty-one patients with locoregionally advanced NPC confirmed by pathology were examined by blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) before and after CCRT, and conventional MRI was performed 3 months after the completion of CCRT. All patients were divided into a responding group (RG) and a nonresponding group (NRG), according to MRI findings 3 months after the end of treatment. The R2* values before (R2*preT) and after (R2*postT) CCRT and the ΔR2* (ΔR2*=R2*postT – R2*preT) were calculated in the tumor. Results: Among the 41 patients, 26 were in the RG and 15 were in the NRG. There was no statistical difference in the R2*preT between RG and NRG (P = 0.307); however, there were significant differences in R2*postT and ΔR2* (P < 0.001). The area under the curve of R2*postT and ΔR2* for predicting the therapeutic response of NPC was 0.897 and 0.954, respectively, with cutoff values of 40.95 and 5.50 Hz, respectively. Conclusion: The R2* value can be used as a potential imaging indicator to evaluate the therapeutic response of locoregionally advanced NPC. [ABSTRACT FROM AUTHOR]

Underground coal gasification (UCG) is a green mining technology with less interference to the environment of mining area. However, underground coal gasification also can cause surface subsidence, which will affect the mining area environment. Therefore, it is necessary to study the evaluation method of surface subsidence degree of underground coal gasification to provide scientific basis for environment influence assessment of underground coal gasification. However, few current researches are conducted on the evaluation of surface subsidence degree of underground coal gasification (UCG). To solve this problem, this paper firstly proposes the process for assessing surface subsidence degree of UCG, and then offers a new method of surface subsidence prediction of UCG based on continuum-stochastic medium theory by combining the characteristics of strata movement of UCG without shaft. Meanwhile, the new approach was applied to evaluate the subsidence degree of UCG experiment site of Ulanqab mine. It was found that the subsidence area of UCG test site was in Class I damage, and have slight impact on the environment of the mining area. The safety of ground buildings can also be guaranteed. The research results own important theoretical significance for the environment impact assessment caused by underground coal gasification and UCG industrialization. [ABSTRACT FROM AUTHOR]

How to accurately estimate the probability integral parameters based on the measured data has always been a difficult point in the application of the probability integral method. This paper introduced FWA into the solution of the probability integral method for the first time. Based on the analysis of strengths and weaknesses of FWA, IFWA (improved fireworks algorithm) was proposed. Then, the IFWA-based inversion model for probability integral parameters (MIFWA) was constructed by the fusion the mining subsidence law and probability integral method. Experiments show that MIFWA has better performance in anti-errors of the observation and the geological mining generalization. [ABSTRACT FROM AUTHOR]

High-grade highways constitute an important transportation infrastructure in coal mine areas in China. The surface subsidence caused by coal mining under high-grade highways poses a serious threat to the safety of high-grade highways. It is imperative to study the influence of mining-induced surface subsidence on high-grade highways. Zouji high-grade highways connect Zoucheng city and Jining city and pass over Nantun Coal Mine. Hence, coal resource exploitation in Nantun Coal Mine negatively affects high-grade highways. The 7328 working face belongs to the upper layers of No. 3 coal of Nantun Coal Mine. A field survey of deformation monitoring points above No. 7328 working face and a field investigation of high-grade highways damage area are performed to examine the subsidence relationship between high-grade highways pavement and surface, high-grade highways deformation and failure characteristics. The results are as follows: (1) the pavement subsidence is essentially consistent with the surface subsidence. When the pavement produces an uplift, the pavement subsidence is lower than surface subsidence. (2) Due to the discontinuous deformation of uplifts and cracks, the inclination curves exhibit obvious fluctuations. (3) The pavement cracks occur in the tensile area. The generation and development of pavement cracks mainly occur prior to the working face advances under the high-grade highways. Advances in working face increases the surface movement and deformation although the cracks width exhibits only a slight change. (4) The pavement uplifts occur in the compression deformation zone. The measured uplift height is between 5 and 15 cm, the length is between 5 and 12 m and the width is between 2 and 9 m. The horizontal profile of uplift generally corresponds to a long and narrow oval. (5) Given a strong stiffness and anti-deformation ability, the kerb also experiences compression failure within 24 h, and this mainly includes folding fracture or comminuted fracture. It is expected that the results of the study can guide coal exploitation under Zouji high-grade highways and provide an experimental reference for coal exploitation under high-grade highways in other mining areas. [ABSTRACT FROM AUTHOR]

The storage of supercritical carbon dioxide in the coal underground gasification combustion cavity can not only reduce greenhouse gas emissions, help control global climate change, but also avoid potential geological hazards caused by the long-term existence of coal-burning holes. It is an important innovative development direction for the global coal industry. However, currently, there is insufficient examination of the practicality and hazards of UCG-CCS through industrial trials, which considerably restricts the spread and use of UCG-CCS. This study employs theoretical analysis and numerical simulation to examine the geological feasibility of UCG-CCS. It finds that the risk of carbon dioxide leakage in UCG-CCS is predominantly due to overlying rock fractures being diffused by the integrity of the cover layer and the parameters of the gasification furnace. It has also been found that the development height of cap rock fractures is closely related to CO 2 injection pressure and gasification furnace width. As CO 2 injection pressure increases, the capping fracture exhibits a descending trend resembling a stair-step; as gasification furnace width decreases, the development height of cap rock fractures decreases. On this basis, the technical approach and design method of preventing carbon dioxide leakage in UCG-CCS are proposed. The research findings have significant theoretical and practical implications for site selection and risk assessment in UCG-CCS process engineering. • This paper verifies the feasibility of UCG-CCS from the geological perspective. • The study confirmed that caprock fractures are the most significant potential pathway for leakage in UCG-CCS projects. • Measures the impact of CO 2 injection pressure and gasifier parameters on the development of overburden fractures in UCG-CCS. • Optimal storage parameters for UCG-CCS were designed to ensure both the best security and economic benefits. [ABSTRACT FROM AUTHOR]