RESUMEN
In order to improve the wettability and permeability of coal seams, the water injection efficiency of coal seams has to be boosted, the amount of dust generation has to be reduced, and coal and gas outburst must be prevented, and a surfactant is used to modulate the coal surface wettability. In this work, taking coal samples from Pingdingshan mine in Henan as the research object, their surface chemistry was initially scrutinized and then coal surface engineering via surfactants was inspected by a contact angle test. The coal wettability was ameliorated with surfactants, particularly using the 1 wt% non-ionic surfactant Triton X-100, which elicited a 47% lower contact angle than the raw coal. The surface free energy of the coal sample modified by 1.0 wt% Triton X-100 was increased from 44.51 mN m-1 to 49.52 mN m-1. The microstructural characteristics of coal samples allowed leveraging the Wiser model to construct three kinds of surfactant-coal adsorption models to dissect the adsorption configuration of the system. The results indicate that the addition of surfactants increases both the interaction of water with the coal and the diffusion coefficient of water molecules, resulting in the coal surface transformation from hydrophobicity to hydrophilicity. Our current work can provide salutary guidance and reference for coal water injection and dust suppression.
RESUMEN
The spatio-temporal dynamics of population and its impact on the regional ecosystem quality in Beijing were analyzed at city-county-township hierarchical levels during 2000 to 2010, based on the 5th and 6th population census data and MODIS-NDVI thematic data. We found that the resident population of Beijing increased by 43.9% during the study period, and the trend of population gathering to the urban fringe resulted in an obviously circular distribution. The annual maximum NDVI of Beijing had the trend of increase, however, decreased significantly between the 5th Ring and the 6th Ring. The change trends of NDVI in urban and exurban areas showed significantly negative relationships with the change ratios of population density, respectively. The increment of urban population caused by urbanization did not show negative influence on the regional ecosystem quality of Beijing. On the contrary, the ecosystem quality in urban core and exurban areas was improved, due to the adjustment of city functions and the population transfer from rural to urban area. Therefore, the functional orientation and development mechanism were the main contribution to the evolution of population pattern and its ecological impacts.
Asunto(s)
Ecosistema , Dinámica Poblacional , Urbanización , Beijing , Ciudades , Humanos , Población Rural , Análisis Espacio-Temporal , Población UrbanaRESUMEN
We used land cover data derived from Landsat thematic mapper (TM) and land surface temperature (LST) data from moderate-resolution imaging spectro-radiometer (MODIS) satellite images to study the variations in LST in July of different land cover types in Beijing-Tianjin-Tangshan urban agglomeration. Ordinary linear regressions (OLS) models and geographically weighted regressions (GWR) models were used to investigate the relationships between the proportions of land cover types and LST. The results showed that great variations in LST occurred among different land cover types. The average LST ranged from high to low in the order of developed land (40.92±3.49 â), cultivated land (39.74±3.74 â), wetland (35.42±4.33 â), and forested land (34.43±4.16 â). The proportions of land cover types were significantly related to LST, but with spatial non-stationarity. This might be due to inherent difference in land cover across locations, and the surrounding environments. GWR models had higher R2 values, compared to OLS, indicating better model performance. In addition, GWR models could reveal the spatial non-stationarity of the relations between LST and the proportions of different land cover types.