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To explore the hazard zone of coal spontaneous combustion in the adiacent goaf at different stages of the roadway driving face, the 2202 working face and the 2201 adjacent goaf of Yingpanhao Coal Mine were taken as examples. The large-scale experiment was conducted to analyze the coal spontaneous combustion limit parameters of the 2201 goaf. The conditions for identifying the hazard zone of coal spontaneous combustion in the adjacent goaf were proposed. Monitoring the gas concentration and temperature in 2201 adjcent goaf by the drilling holes through coal pillar, and the numerical simulation was conducted to study the oxygen concentration distribution in 2201 adjcent goaf, and the hazard zone of coal spontaneous combustion in the adjacent goaf was obtained. The results show that during the mining period of the 2202 working face, the coal pillar was broken by the stress concentration, and the oxygen volume fraction of the adjacent goaf was in the range of 10.1% to 13.8%. The oxygen volume fraction of the adjacent goaf before the stop mining period was between 10.3% and 15%. During the mining period, a narrow area on the coal pillar side with width 55 m from the front 45 m and behind 119 m of 2202 working face in the adjacent goaf was the coal spontaneous combustion hazard zone. Before the stop mining period, a narrow area on the coal pillar side with width 42 m from the front 63 m and behind 107 m of 2202 working face in the adjcent goaf was in an oxidizing environment.

Mao, D., Feng, C., Zhou, H., Hu, G., Li, Z., & Guo, R. (MarchApril, 2017). The runoff variation characteristics of Dongting Lake, China. Water Technology and Sciences (in Spanish), 8(2), 77-91. The runoff variation characteristics of Dongting Lake were analyzed by applying the methods of concentration degree, concentration period, Mann-Kendall trend test, and variation coefficient. The analysis showed that: 1) The runoff concentration period of Dongting Lake occurs mainly between June and July of each year, with the peak time in late June–early July, and the composite vector directions in concentration period range from 103.2° to 190.2°; 2) The runoff variation coefficient ranges from 0.194 to 0.761, which indicates the instability of runoff. Extreme ratios of inflow and outflow are over 0.6 with an obvious attenuation; 3) The alternating pattern between wet years and dry years showed that the water distribution of the four rivers is relatively equal, while Ouchikou from three bayous is more violent, accounting for 32.79% of wet years and 57.38% of dry years respectively. The drastic change of annual water allocation is adverse to rational utilization of water resources.

Over the past few decades, the spontaneous combustion of large-scale coal stockpile is frequent due to natural airflow contacted the surface and entered in the voids of coal stockpile, coal is oxidized and accumulated the heat, and then coal spontaneous combustion occurred, which seriously caused the waste of natural resources and environmental pollution. In this study, based on the principle of heat transfer by heat pipe (HP), an experiment is conducted to study the effect of heat transfer by HP, such as the temperature difference and heat transfer ratio, heat transfer radius, cumulative heat transfer volume, in a coal stockpile as its heating temperature increased from 100°C to 150°C under the different lab conditions. The results indicated that the average temperature drop scale in the coal stockpile by HP was 46.3%, 10.8%, and 32.8% that under the lab conditions, respectively. A comparison study revealed that as the inserted angle of HP in the coal stockpile is 60º, the heat transfer effect of HP is significantly affected by outside ambient, especially sensitive to airflow. For instance, as the HP inserted scale is 1:4, outside air velocity is 2.0 m/s, the maximum heat transfer radius in the coal stockpile is 49.2 cm, the overall heat transfer effect enhanced by 79% and 93% that with the heating temperature in the coal stockpile is 100°C and 150°C, respectively. Therefore, it can be concluded that the utilization of HP is a reasonable method to remove the accumulated heat in the coal stockpile, as well as the suitable arrangement is also significantly important before this technique is conducted. This study provided a new technical approach and theoretical basis for the prevention and control before the large-scale stockpile has the risk of spontaneous combustion. [ABSTRACT FROM AUTHOR]

To explore the effects of methane on the characteristics of coal spontaneous combustion, coal low-temperature oxidation and Fourier transform infrared spectroscopy experiments were conducted. The tested airflows had an oxygen–nitrogen ratio of 0.266, and methane concentrations of 0−3% by volume. Moreover, the coal oxidation characteristics and the various types and quantities of functional groups were investigated. The results show that CO/CO2 production and oxygen consumption rates were higher for coal samples under airflow atmospheres containing methane than for airflow atmospheres without methane. However, the apparent activation energy of coal samples in airflows containing methane was lower than for airflow atmosphere without methane. It is speculated that airflows with 1−3% methane concentrations have a positive impact on coal spontaneous combustion. This study used OMNIC and PeakFit v4.12 programs to analyze the effect of airflows containing methane on the functional groups of coal spontaneous combustion. The Pearson correlation coefficient method was introduced to analyze the relationship between the key functional groups and apparent activation energies of coal samples. The results indicated that the key functional groups of the coal samples below the critical temperature were methyl (−CH3) and methylene (−CH2). Above the critical temperature, aromatic C−H, methyl (−CH3), and methylene (−CH2) were the key functional groups. After reaching the cracking temperature, aromatic C−H and alkyl ether C−O−C became the key functional groups. With increasing methane concentration, aromatic C–H makes a negative contribution to coal spontaneous combustion, while methyl (−CH3) and methylene (−CH2) make positive contributions. The inhibition of alkyl ether C−O−C to coal spontaneous combustion is weakened, and the inhibition of aromatic ring C=C to coal spontaneous combustion is enhanced. [ABSTRACT FROM AUTHOR]

Mao, D.; Fu, X.; Wang, J., and Guo, R., 2019. Assessment of flood vulnerability of the Dongting Lake Area in China with regard to land use/cover change. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 388–396. Coconut Creek (Florida), ISSN 0749-0208. A flood vulnerability comprehensive evaluation model (FVCEM) was established by interpreting remote sensing (RS) image data for 1987, 1998, and 2008 using Environment for Visualizing Images (ENVI) software and a geographical information system (GIS), as well as analysing historical disaster maps and statistical yearbook data regarding flood disasters in the Dongting Lake Area in China. Using the method of analytic hierarchy process (AHP) etc., the influence of land use/cover change on flood vulnerability was studied. The vulnerability of the local population and economy to flooding was assessed by means of FVCEM. The results showed that the vulnerability parameters of hazard-affected bodies were different for different land use types, which influenced the subsequent flood vulnerability. The flood vulnerability value over the period of 1987-2008 exhibited an increasing trend, with obvious spatial heterogeneity. The hinterland of the Dongting Lake Area was found to be susceptible to flood hazard. The flood risk regionalization and risk management should be carried out urgently by local government according to the temporal and spatial vary characteristics of flood vulnerability, land use model suitable for these characteristics should be constructed timely by residents. [ABSTRACT FROM AUTHOR]

Balancing ecological environment protection (EEP) and economic development (ED) (balance for short) is a difficult problem that must be solved in the development of modern society, particularly important for realizing UN Sustainable Development Goals. How to assess the regional balance situation and reveal the spatial and temporal heterogeneous characteristics of the balance (especially for the vast China) and its influencing factors are the primary scientific problems and realistic needs. Taking Zhejiang, Hunan and Gansu Provinces in the eastern, central and western region of China as a regional representative, an index system characterizing EEP and ED were established, which were processed by extreme difference method and entropy weight method. The coupling characteristics, stress factors and coordination type from 2010 to 2019 in the 3 provinces were assessed and analyzed by means of the coupling coordination model and the grey correlation degree model. Balance is the mission and responsibility of the spatial planning system for spatial planning is of the source, whole-region and comprehensiveness of public strategy, therefore, the balance strategies and its integration approaches are constructed in the 3 provincial spatial planning based on the assessment and analysis of balance characteristics. Research results show that: (1) the 3 provinces' coupling coordination degree is rising year by year, coordination type is more and more better indicating that the balance of EEP and ED is getting better and better, but coordination type differentiates at one level between 3 provinces at the east, central, western region of China, Zhejiang province is from nearby imbalance to primary coordination, Hunan Province is from nearby imbalance to narrow coordination, and Gansu Province is from medium imbalance to nearby imbalance. (2) The ED have same strong stress on EEP in the 3 provinces, and the constraints of EEP on ED are different, the current balance characteristics of Zhejiang, Hunan and Gansu province are the types of ecological environment pressure constraints primary coordination, ecological environment pressure constraints narrow coordination, and ecological environment condition constraints nearby imbalance. (3) The coordination types are the co-environmental pressure constraints primary coordination (Zhejiang Province), eco-environmental pressure constraints narrow coordination (Hunan Province) and eco-environmental condition constraints nearby imbalance (Gansu Province), and corresponding balanced planning strategy system are to promote ecological modernization, implement ecological industrialization and adhere to the ecological fundamentalization., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

An efficient approach for organoselenium-catalyzed regioselective C-H pyridination of 1,3-dienes to form pyridinium salts has been developed. This method was also successfully applied to direct C-H pyridination of alkenes. Fluoropyridinium reagents, or initially loaded pyridine derivatives, acted as pyridine sources in the pyridination reactions. The obtained pyridinium salts could be further converted under different conditions. This work is the first example of catalytic C-2 direct C-H functionalization of 1,3-dienes and the first case of organoselenium-catalyzed C-H pyridination., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)