Urban land use classification is significant for urban development planning. Considering complex environments of urban surface features, traditional semantic segmentation methods are difficult to ...solve the problems of mixed pixels and limited spatial resolution of images. The subpixel mapping technology is an effective method to solve the above problems in urban land use classification. However, traditional subpixel mapping methods are sensitive to mountain shadow, high-rise building shadow and impermeable surface heterogeneity, resulting in false classification. Therefore, we propose a subpixel mapping method that can reduce the shadow effect. This method uses a multi-index feature fusion strategy to optimize the abundance of the shadow errors in the abundance image, and uses a super-resolution reconstruction neural network model to reconstruct the optimized abundance image for the subpixel mapping of urban land use. Experiments were conducted on Sentinel-2 images obtained over Yuelu District of Changsha City, Hunan Province, China. The experimental results show that the method proposed in this paper can effectively overcome the influence of building shadows and mountain shadows in urban land cover classification and is superior to traditional SPSAM, RBF, SRSPM and other methods in the effect and accuracy of urban land use subpixel mapping.
The present study explores a three-dimensional deformation monitoring method for the better delineation of the surface subsidence range in coal mining by combining the mining subsidence law with the ...geometries of SAR imaging. The mining surface subsidence of the filling working face in Shandong, China, from March 2018 to June 2021, was obtained with 97 elements of Sentinel-1A data, the small baseline subset (SBAS) technique, and the proposed method, respectively. By comparison with the ground leveling of 46 observation stations, it is shown that the average standard deviation of the SBAS monitoring results is 10.3 mm; with this deviation, it is difficult to satisfy the requirements for the delimitation of the mining impact area. Meanwhile, the average standard deviation of the vertical deformation obtained by the proposed method is 6.2 mm. Compared to the SBAS monitoring accuracy, the monitoring accuracy of the proposed method is increased by 39.8%; thus, it meets the requirements for the precise delineation of the surface subsidence range for backfill mining.
Underground coal gasification (UCG) is an important part of the low-carbon green coal mining technology system. With the implementation of the carbon peaking and carbon neutralization and the ...maturity of UCG, UCG will inevitably perform large-scale and industrialized production, which will certainly cause some issues such as serious waste of UCG sites caused by large-scale surface residual subsidence and poor foundation of fractured rocks. The key to the reuse of the surface site after UCG is to ensure that the surface residual subsidence does not exceed the design index of the building (structure). However, there is still a lack of methods for predicting residual subsidence on the surface of UCG. Under such background, combined with the characteristics of the UCG process, this paper analyzed the mechanism of the surface residual subsidence after UCG, and concluded that the root resource of the surface residual subsidence after UCG was the stripping and yielding of the hyperbolic coal pillars. Next, a calculation model of the maximum stripping width and yielding zone width of the “hyperbolic” coal pillar for UCG was established by the theoretical analysis method, and a method for predicting the surface residual subsidence with the consideration of coal pillar stripping and yielding was proposed and applied to Ulanqab UCG test site. The research findings have important theoretical and practical significance for the UCG site stability evaluation and land resource reuse.
•We obtained and demonstrated the optimized parameters of both the horizontal and vertical channels of the linear-in-wavenumber, which validate the feasibility of the proposed dual channel ...linear-in-wavenumber spectra camera used for the polarization detection.•The key performances including the axis resolution, the effective imaging range and the pixel alignment of the developed SD-PS-OCT are evaluated both theoretically and experimentally.•The phase retardation of a Babinet-Soleil compensator and the optic axis orientation of a quarter wave plate are quantitatively measured with high accuracy.•The depth-resolved images of the intensity, the phase retardation and the optic axis orientation of the ex-vivo tendon tissue and the chicken muscle tissue are reconstructed, which verified the feasibility of the proposed method.
A single input state, single mode fiber (SMF) based spectral domain polarization sensitive optical coherence tomography (SD-PS-OCT) system using a single linear-in-wavenumber spectral camera is presented. With the proposed dual channel linear-in-wavenumber spectral camera and the polarization alignment procedure, the orthogonal polarization components of the spectral interference signal can be detected using the all SMF based SD-PS-OCT system without any bulk polarization optical elements. To evaluate the performance of the developed system, the polarization properties of a Babinet-Soleil compensator and a quarter waveplate are quantitatively measured with high accuracy. Furthermore, the depth-resolved images of the intensity, the phase retardation and the optic axis orientation of the ex-vivo tendon tissue and the chicken muscle tissue are reconstructed to verify the feasibility of the proposed method.
Underground coal fire is a global geological disaster that causes the loss of resources as well as environmental pollution. Xinjiang, China, is one of the regions suffering from serious underground ...coal fires. The accurate monitoring of underground coal fires is critical for management and extinguishment, and many remote sensing-based approaches have been developed for monitoring over large areas. Among them, the multi-temporal interferometric synthetic aperture radar (MT-InSAR) techniques have been recently employed for underground coal fires-related ground deformation monitoring. However, MT-InSAR involves a relatively high computational cost, especially when the monitoring area is large. We propose to use a more cost-efficient Stacking-InSAR technique to monitor ground deformation over underground coal fire areas in this study. Considering the effects of atmosphere on Stacking-InSAR, an ERA5 data-based estimation model is employed to mitigate the atmospheric phase of interferograms before stacking. Thus, an adaptive ERA5-Corrected Stacking-InSAR method is proposed in this study, and it is tested over the Fukang coal fire area in Xinjiang, China. Based on original and corrected interferograms, four groups of ground deformation results were obtained, and the possible coal fire areas were identified. In this paper, the ERA5 atmospheric delay products based on the estimation model along the LOS direction (D-LOS) effectively mitigate the atmospheric phase. The accuracy of ground deformation monitoring over a coal fire area has been improved by the proposed method choosing interferograms adaptively for stacking. The proposed Adaptive ERA5-Corrected Stacking-InSAR method can be used for efficient ground deformation monitoring over large coal fire areas.
The contradiction between coal mining and urban construction in coal resource-based cities is prominent, which greatly limits the sustainable development of these cities. Pan’an New City is a key ...mining-induced subsidence area in Xuzhou City, which presents significant challenges to the construction of the new city. Therefore, in order to ensure the safe construction of Pan’an New City, the residual deformation and stability of the goaf sites must be monitored and evaluated. Under such background, based on the measured leveling data of the mining-induced surface deformation in a coal mine near Pan’an New City, this paper first analyzed the accuracy of InSAR monitoring of surface deformation in coal mining subsidence area by SBAS-InSAR technology. Then, the SBAS-InSAR technology was used to monitor the surface subsidence rate and cumulative subsidence in the coal mining subsidence area of Pan’an New City, based on the 29 scene SAR data during Dec. 2020 and Jan. 2022. The results showed that the goaf site in the north and northwest of Pan’an New City is unstable, while the other areas are stable. Finally, according to the monitoring results, the suggestions have been put forward for the construction of Pan’an New Town on the goaf site. The research results have important theoretical and practical significance for the reuse of goaf sites in Pan’an New City and similar areas in Xuzhou.
Resource-based cities often face land scarcity during their developmental and expansionary phases. However, repurposing the goaf sites of suburban coal mines has been recognized as an effective ...strategy for alleviating this issue, particularly pertinent for suburban coal mines using strip mining techniques to protect ground-level structures. Old strip mining goaf is easily influenced by disturbance and leads to secondary surface deformation, which will threaten the construction above old strip mining goaf. Therefore, it is essential to provide a basis and reference for decision-makers regarding surface residual subsidence for strip mining. In the paper, based on the morphology and structure of the old strip mining goaf before the surface residual subsidence, the reason and mechanism of the residual subsidence of old strip mining goaf are studied. The results show that the main reasons for the “activation” of old strip mining goaf are the re-compaction of the under-compacted part of the fractured rock mass in the caving zone, the stripping and yielding of coal pillar under the action of groundwater erosion, weathering, and the collapse of residual voids. Based on the above analysis, a prediction model of the surface residual subsidence of the old strip mining goaf is proposed, which takes into account the compaction of the under-compacted area, the collapse of the residual voids, and the stripping and yielding of the coal pillar. The proposed method is implemented to evaluate the stability of a city viaduct goaf. Our research outcomes bear valuable theoretical and practical implications for site stability assessments of old strip mining goafs and the sustainable repurposing of land resources in suburban resource-based cities.
Histone demethylases containing JumonjiC (
) domains regulate gene transcription and chromatin structure by changing the methylation status of lysine residues and play an important role in plant ...growth and development. In this study, a total of 332
family genes were identified from 21 different plant species. The evolutionary analysis results showed that the
gene was detected in each species, that is, the gene has already appeared in algae. The phylogenetic analysis showed that the KDM3/JHDM2 subfamily genes may have appeared when plants transitioned from water to land, but were lost in lycophytes (
). During the evolutionary process, some subfamily genes may have been lost in individual species. According to the analysis of the conserved domains, all of the plant
genes contained a typical JmjC domain, which was highly conserved during plant evolution. The analysis of
-acting elements showed that the promoter region of the
gene was rich in phytohormones and biotic and abiotic stress-related elements. The transcriptome data analysis and protein interaction analyses showed that
genes play an important role in plant growth and development. The results clarified the evolutionary history of
family genes in plants and lay the foundation for the analysis of the biological functions of
family genes.
The mining of shallow coal seams with hard roofs poses a threat to surface structures. In order to ensure the protection of these buildings, backfill mining is increasingly used in these types of ...coal seams. However, due to the lack of appropriate surface subsidence prediction methods, there are concerns about whether backfill mining can meet the requirements of building protection. In this study, through numerical simulation and physical experiments, the movement characteristics of the strata and surface were studied in the backfill mining of a shallow coal seam with a hard roof. Our results indicate that the backfilling ratio significantly influences strata movement and surface subsidence. As the backfilling ratio increases, the surface deformation in the backfill under the hard roof of the shallow coal seam transitions from discontinuous to continuous. When the backfilling ratio exceeds 60%, the deformation characteristics of the overburden and surface align with the probability integral method model. Consequently, a novel surface subsidence prediction method for backfill mining in shallow coal seams under hard roofs is proposed. This method was successfully applied at Yungang Mine, validating its effectiveness. These research findings have significant practical implications for the design of backfill mining in shallow coal seams under hard roofs.
We present a miniaturized precalibration-based forward-viewing Lissajous scanning fiber probe for high speed endoscopic optical coherence tomography (OCT). The probe is based on an asymmetric fiber ...cantilever driven by the piezoelectric bender to realize two-dimensional (2D) Lissajous scanning. The stability and repeatability of the Lissajous scanning trajectory of the probe is tested by a position sensitive detector (PSD)-based position calibration setup. The two orthogonal resonant frequencies of the cantilever are measured to be 167.2 and 121 Hz. A 25 µm focal spot is formed at the working distance of 5 mm by the graded-index (GRIN) lens, and the field of view of the imaging probe is around ${1.5}\;{\rm mm} \times {1.5}\;{\rm mm}$1.5mm×1.5mm. The probe is fully packaged in a hypodermic tube for endoscopic imaging. The total rigid length and outer diameter are 35 mm and 3.5 mm, respectively. The probe is incorporated in a 50 KHz swept source OCT system with the axial resolution of 14 µm, and its imaging performance is validated by the 2D en face and 3D volumetric OCT imaging of the phantom and the biological tissue.
