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A multipath error is one of the main sources of GNSS positioning errors. It cannot be eliminated by forming double-difference and other methods, and it has become an issue in GNSS positioning error processing, because it is mainly related to the surrounding environment of the station. To address multipath errors, three main mitigation strategies are employed: site selection, hardware enhancements, and data processing. Among these, data processing methods have been a focal point of research due to their cost-effectiveness, impressive performance, and widespread applicability. This paper focuses on the review of data processing mitigation methods for GNSS carrier-phase multipath errors. The paper begins by elucidating the origins and mitigation strategies of multipath errors. Subsequently, it reviews the current research status pertaining to data processing methods using stochastic and functional models to counter multipath errors. The paper also provides an overview of filtering techniques for extracting multipath error models from coordinate sequences or observations. Additionally, it introduces the evolution and algorithmic workflow of sidereal filtering (SF) and multipath hemispherical mapping (MHM), from both coordinate and observation domain perspectives. Furthermore, the paper emphasizes the practical significance and research relevance of multipath error processing. It concludes by delineating future research directions in the realm of multipath error mitigation. [ABSTRACT FROM AUTHOR]

A water-bursting evaluation of the coal seam floor is critical to ensure safety of coal mine production. The vulnerability index method based on AHP is selected for this study's evaluation method. Water pressure, measured specific yield, equivalent thickness of effective aquiclude, brittle rock thickness under mining pressure damage zone, distribution of faults, distribution of collapse column, distribution of endpoints, and the intersection of fault are taken as the evaluation index based on the analysis of geological data in the study area. The authors assessed the threat posed by the two aquifers in the lower portion of the coal seam. Separate evaluations were conducted on the Benxi and Ordovician limestone aquifers. The results' veracity was confirmed by comparing the obtained results to the water bursting point and a few boreholes. The evaluation results provide recommendations for the safe operation of coal mines. [ABSTRACT FROM AUTHOR]

Zhang, L.; Dong, D.; Zhang, F., and Xu, Z., 2020. A novel three-dimensional mine area hydrogeological model based on groundwater modeling systems. In: Hu, C. and Cai, M. (eds.), Geo-informatics and Oceanography. Journal of Coastal Research, Special Issue No. 105, pp. 141–146. Coconut Creek (Florida), ISSN 0749-0208. Three-dimensional(3D) geological modeling has received extensive attention and research in the fields of energy exploration, geological survey, disaster prevention, and groundwater simulation. In this article, a novel 3D visualization geological model of the mining area based on the groundwater modeling system (GMS) is proposed. Also, 3D spatial combination characteristics of the hydrogeological structure of the mining area are analyzed and investigated. To attain better optimization parameters, the spatial distribution of water flow field and the temporal variation characteristics of groundwater level are derived. The simulation shows that the model is of theoretical value for 3D visualization of mine geology and numerical survey of groundwater. [ABSTRACT FROM AUTHOR]

The fundamental purpose of the security system in a nuclear power plant is to thwart any adversary attempting to breach the facility by means of detection, delay, and response. This study introduces a novel flow intrusion model (FIM) that integrates the EASI method and Bayesian Attack Tree to assess the effectiveness and sensitivity of the security system. In contrast to the conventional effectiveness evaluation technique, which utilizes the enumeration method to compute the vulnerable path, the FIM method concentrates on a thorough analysis of the dynamic and static risks inherent in the security system. To facilitate a practical analysis of the FIM, a minimum case is presented. [ABSTRACT FROM AUTHOR]

Grouting is extensively used in mining areas susceptible to potential water hazards. However, as time elapses, grout composites can fail, thereby jeopardizing the subsurface aquifer system and giving rise to groundwater contamination. This study involved the production of standardized grout composite specimens, followed by laboratory immersion testing. After a 180 days of immersion, the mass of the grout composite was reduced by 19.83 g, constituting a 0.86% reduction from its initial weight, accompanied by a gradual increase in the permeability coefficient. By integrating the experimental outcomes, a groundwater pollutant transport model was developed to elucidate the effect of this failure process. According to the model results, no distinctive pollutant ions would be detected in other aquifers within a decade following grouting completion as the grout composite retained its strength during this period. After 30 years, the highest concentration of ferrous ions in the target aquifer reached 0.16 mg/L, which though low, suggests that failed grout composites can serve as conduits for pollutant transport, and thereby adversely affect the water quality of other aquifers. [ABSTRACT FROM AUTHOR]