陕西省是我国水土流失严重省份和黄河的主要产沙区,为了给陕西省及黄河流域水土流失治理提供理论参考,基于逐月降水量数据和土壤属性、NDVI、DEM、土地利用等数据,采用RUSLE模型计算土壤侵蚀模数,并采用最大变化率法对2000—2015年陕西省土壤侵蚀强度时空变化的主要驱动因子进行了识别.结果表明:陕西省土壤侵蚀分布异质性较强,剧烈和极强烈侵蚀主要分布在陕北地区、少数分布在关中地区北部区域;2000—2015年陕西省土壤侵蚀强度总体呈现下降趋势,其中陕北地区土壤侵蚀强度一直呈下降趋势、关中和陕南地区呈现先升后降的变化趋势;陕西省土壤侵蚀强度时间变化的主要驱动因子,2000—2005年为降雨侵蚀力和植被覆盖,2005—2015年为降雨侵蚀力,2000—2015年长时段总体上为植被覆盖;陕西省土壤侵蚀强度空间变化主要驱动因子为植被覆盖和地形,其中榆林、铜川、宝鸡、西安、商洛、安康、汉中七市的主要驱动因子为植被覆盖,渭南、咸阳两市的主要驱动因子为地形,延安市的主要驱动因子为降雨侵蚀力.最大变化率法可用于识别土壤侵蚀时空变化的主要驱动因子,但在识别时间变化主要驱动因子时对降雨侵蚀力极端值较为敏感,应尽量扩大时间步长以消除其影响.

为了研究三峡水库175 m试验性蓄水运行后的库区水质时空变化规律,基于2008～2019年三峡库区逐月水质监测数据,采用Mann-Kendall非参数检验法和水质质量指数(WQI)综合评估法分析了三峡库区蓄水后水质时空分布特征.结果表明:三峡库区水质主要超标项目为总磷和高锰酸盐指数,上游总磷、高锰酸盐指数超标现象大于下游;2008～2019年高锰酸盐指数、总磷浓度整体呈缓慢下降趋势;2016年是干流总磷浓度变化的突变节点,干流的总磷浓度在2016年之后有显著下降趋势;三峡库区干支流水质质量指数整体处于上升趋势,支流水质质量指数整体低于干流,丰水期水质质量指数低于枯、平水期.研究成果可以为三峡库区水环境保护和管理提供科学依据.

Enhancing the water cooling islands (WCIs) effect of urban water bodies is one strategy to alleviate high temperatures in urban areas. At present, the influencing factors of WCIs effect have been investigated comprehensively, but the relative importance of these factors has not been compared. In this case, urban planners cannot give priority to the most important factors when using WCIs to weaken urban heat islands effect in urban planning. Shenzhen, located in the south of Guangdong Province, China, is a rapidly urbanizing city with abundant urban water bodies. The urban heat islands effect in Shenzhen has already become severe as the city is affected by the climate and the urbanization process. This study compared the seasonal variations of WCIs in Shenzhen and explained WCI intensity based on landscape pattern, geographical location, and surrounding land cover. The main influencing factors of the WCI intensity were identified by stepwise regression analysis. The results showed that the WCIs effect was evident in all four seasons, and the intensity of cooling was the greatest in the summer, followed in decreasing order by autumn, spring, and winter. The main influencing factors found in this study include water area, elevation, and surrounding land cover. In general, surrounding land cover has a greater impact than water area during all four seasons and has a greater impact than elevation in spring, summer, and autumn. These main influencing factors have a greater impact than other factors and can be used as indicators to predict the WCI intensity of water bodies in the future. In addition, the threshold of water area affecting WCI intensity was observed, and the heat island water bodies were found in all four seasons. Among the surrounding land cover buffers of water bodies, the optimal buffer was the most correlated to the WCI intensity, and the warmer the season, the smaller the optimal buffer. This study highlights these main influencing factors, and they will help urban managers reasonably modify existing water bodies or plan new ones.

随着4G商用以及不限量套餐的推广,4G业务量迅猛增长,4G网络容量受到极大挑战.由于热点区域较为集中,局部区域出现严重高负荷,客户感知差、投诉多问题.为了解决该问题,通过部署3DMIMO、MU MIMO、QCI&QoS等新技术,解决大话务场景下的网络容量,有效提升无线网络质量和用户感知.

本文基于GMS平台,在综合分析重庆某山区地质平面图、地质剖面图、钻孔资料等数据基础上构建了三维可视化地质模型.模拟结果表明:研究区砂泥岩倾斜互层的沉积顺序和不同岩性的空间分布情况与该区已有资料相一致;模型剖面与实际地质剖面面积之比约为1.15,主要岩性面积百分比相对误差绝对值均在15％以内.运用该模型概化为三维水文地质模型,模拟得出研究区地下水流场空间分布,体现了三维地质模型在地下水数值模拟方面的运用价值.该模型的构建为山区区域地质结构研究提供了参考,也为今后该地区开展地下水相关工作打下了基础.

准确预测航空公司备件需求是装备保障的一项基本工作,但是备件采购时间过早或者采购数量过多都会使库存成本增加.因此基于指数分布对马尔科夫系统可修备件最优订购时间进行研究,建立了在一定航材保障率下的最优订购数量、最优订购时间的求解模型,并通过算例仿真验证了模型的可行性及实用性.该研究结果对航空公司缩减库存成本有一定的指导意义.

为研究三峡水库不同时期沉积物污染变化规律,采集三峡库区175 m正常蓄水后7条支流表层沉积物样品,分析营养盐、重金属含量和污染特征,结果表明:7条支流表层沉积物均存在营养盐含量超标现象,但仍处于多数底栖生物可承受水平,其中龙溪河21号断面w(TN)和19号断面w(TP)最高,分别为1.97、2.03 g/kg;采用EF(富集因子)和RI(潜在生态风险指数)评价了重金属富集程度和污染水平,重金属EF表现为Hg ＞As＞ Cd＞ Pb＞ Cu ＞Zn＞ Mn＞ Cr,仅Mn和Cr的EF小于1,未受污染;RI平均值为160±35,处于中度生态风险.沉积物中TN、TP来源以农业面源污染为主,TOM主要来源于浮游动物和浮游植物;重金属污染则以流域工业污水排放和农业活动为主.研究显示,三峡库区蓄水后沉积物中营养盐和重金属含量总体呈上升趋势,建议划分优先控制区域,重点解决农业面源污染,强化农村生活污水治理,并以严格的环境准入制度防控和削减流域工业污染.

In order to study the effect of nitrite and nitrate on the performance of microbial fuel cell, a system combining an anaerobic fluidized bed (AFB) and a microbial fuel cell (MFC) was employed for high-strength nitrogen-containing synthetic wastewater treatment. Before this study, the AFB-MFC had been used to treat high-strength organic wastewater for about one year in a continuous flow mode. The results showed that when the concentrations of nitrite nitrogen and nitrate nitrogen were increased from 1700 mg/L to 4045 mg/L and 545 mg/L to 1427 mg/L, respectively, the nitrite nitrogen and nitrate nitrogen removal efficiencies were both above 99%; the COD removal efficiency went up from 60.00% to 88.95%; the voltage was about 375 ± 15 mV while the power density was at 70 ± 5 mW/m(2). However, when the concentrations of nitrite nitrogen and nitrate nitrogen were above 4045 mg/L and 1427 mg/L, respectively, the removal of nitrite nitrogen, nitrate nitrogen, COD, voltage, and power density were decreased to be 86%, 88%, 77%, 180 mV, and 17 mW/m(2) when nitrite nitrogen and nitrate nitrogen were increased to 4265 mg/L and 1661 mg/L. In addition, the composition of biogas generated in the anode chamber was analyzed by a gas chromatograph. Nitrogen gas, methane, and carbon dioxide were obtained. The results indicated that denitrification happened in anode chamber.

通过对三峡库区7条支流表层沉积物中总氮(TN)、总磷(TP)、钾(K)及有机质(OM)的含量进行测定,分析其空间分布特征,评价其污染水平,揭示其污染来源.结果表明,7条支流pH值平均值(7.91±0.53),按照支流沿程分布,表层沉积物各营养盐含量基本呈上升趋势,回水断面和断面营养盐含量较高.仅澎溪河(PX)上游断面表层沉积物各营养盐含量较高,按沿程逐渐降低,到支流回水末端又呈升高趋势.7条支流均未出现有机污染,但受到有机氮污染胁迫;除OM外,25个断面的营养盐(TN、TP)含量基本超过了加拿大安大略省环境和能源部发布的沉积物中能引起水环境生态风险效应的营养物含量评价标准,沉积物已受到污染,但仍属于多数底栖生物可以承受的污染水平.

Based on the connotation of ecological carrying capacity(ECC), framework for ECC analysis was proposed aiming at ensuring ecological security(ES) of water body. In view of the characteristics of Three Gorges Reservoir(TGR) area, the status and historical tendency of ECC of TGR were discussed resting on the calculation of resource carrying capacity,supplemented by comparative analysis of environmental carrying capacity. Results show that appropriate carrying population is presently 1 530.6 ~1 590.7 ×104person. Resource carrying capacity is biggest in key development area, followed by the optimized development areas, lowest in restricted development area. Despite a slight increase of ECC, TGR area keeps an overloading state from 1999 to 2011. Opposite direction between land resources carrying capacity change and economic resources carrying capacity change reflects the extensive economic development mode to some extent. Due to the undeveloped analytical method, ECC of TGR area requires further study. However, for the sake of water environment safety of TGR area,it is strongly recommended to take positive population-load-downsizing measures and improve the carrying efficiencies of resources and environment.

Chongqing is one of China's four largest cities and located at the upstream of the Three Gorges Reservoir. The water pollution in Chongqing Reach of the Yangtze River has been considered as one of important issues to be addressed. The geometry of this reach is quite complex, including many meander segments, several small islands, the confluence of Yangtze River and Jialing River, etc. In addition, the operation of Three Gorges Reservoir by rising or dropping the water level may also affect the flow fields and pollutant transport in this reach. In this study, the unsteady flow fields and pollutant transport in Chongqing Reach were simulated using the numerical model CCHE2D, developed at the National Center for Computational Hydroscience and Engineering, the University of Mississippi. The model is a finite element model utilizing a special method based on the collocation approach called the efficient element method. Two cases were simulated for modeling the unsteady processes of water level rising from the natural level to the maximum 175m and water level dropping from 175m to the natural level due to the operation of the Three Gorges Reservoir. More than thirty point sources from local industries, municipal sewages and small tributaries along the Yangtze River and Jialing River were considered as side pollutant loadings in the model. The simulated flow fields were compared with field measurements for model calibration and validation. It can be found from the simulated results that the processes of water level rising and dropping greatly affect the hydrodynamics as well as pollutant transport in Chongqing Reach. This study shows that the numerical model is capable of providing useful information for water quality management in the Yangtze River.

采用美国密西西比大学国家水科学计算和工程中心开发的CCHE2D二维水力学水质数学模型模拟了三峡回水变动区江段的非恒定流流场及污染物输移扩散过程。该模型采用“有效元”处理技术，模拟了从天然河流状态到三峡蓄水至175 m和从三峡175 m水位下降至天然河流2种状态下回水变动区的水流、水质演变过程；模拟了长江、嘉陵江沿岸有30多个工业和城市生活排污口及小型支流汇入状态下的水质状况；模型用实测水文资料进行了验证和标定。计算结果表明：受三峡水库运行调度的影响，处于回水变动区的长江、嘉陵江重庆段的水流特征及污染物输移受三峡水位涨落影响较大；数值模型可为长江三峡水环境管理提供可靠的理论依据。

In order to study the performance and bacterial communities of an anaerobic fluidized bed microbial fuel cell (AFB-MFC) system, the 16S rDNA gene sequencing was applied, and high-strength synthetic wastewater was treated by the AFB-MFC system. The high-strength synthetic wastewater, in which the concentrations of chemical oxygen demand (COD), nitrite nitrogen, and nitrate nitrogen were above 19,000, 2,516-3,871 and 927-1,427 mg/L, was treated by the AFB-MFC system. The removal efficiency of COD, nitrite nitrogen, and nitrate nitrogen reached 70-89, 98 and 98%, while the maximum voltage was 394 mV. The bacteria analysis revealed the presence of Alistipes putredinis, Carnobacterium sp., Victivallis vadensis, Klebsiella pneumoniae, Thauera sp., Parabacteroides merdae, Parvimonas micra, Parabacteroides sp., and Desulfomicrobium baculatum in the anode chamber. In addition, the Klebsiella pneumoniae was observed to have the capability of organic degradation and electricity generation, while the Thauera sp. has the capability of denitrification.

Microbial fuel cells(MFCs) were introduced in this paper in respects of their composition and structure.The principles and affecting factors of power generation and wastewater treatment related to MFCs were assessed,and the application of MFC technology was analyzed.Finally,the problems concerning the development of MFC technology were summed up.

It is very important to investigate the change of nutrient in Three Gorges Reservoir for analyzing the influence after normal storage and proposing reasonable management methods. The water quality parameters were determined monthly from March in 2008 to February in 2009. Six horizontal monitoring sites and one vertical site were set in Three Gorges Reservoir. The period was separated into two different periods with taking account of the water level after the Three Gorges Reservoir storaged water, which were October-February and March-September respectively. Then, the spatial-temporal variation characteristics of nutrient and environmental features in different periods were studied with the water quality data. The results showed that there were no significant differences of water quality parameters except DO in different periods. There were also no significant differences of the vertical distribution of hydrology, water quality indexes among the three observed levels. The concentration of DO in high water level (8.29 mg/L)was higher than that in low water level (7.49 mg/L) and the mean of saturation degree of DO was 83.5%. Total nitrogen (TN), NH4+ -N, total phosphorus (TP) values were 1.42-2.23 mg/L, 0.15-0.36 mg/L, 0.08-0.14 mg/L respectively, and plane of nutrition in high water level was higher than that in low water level. The main factor influenced the concentrations of TN, NH4+ -N and TP were rainfall runoff process. Significantly positive correlation was observed by correlation analysis between nutrients fluxes and the flux at the section Cun Tan. The fluxes of TN, NH4+ -N, TP were 368.4, 97.2, 29.5 thousands tons respectively, and the non-point pollution accounts for more than 55.5%.

With the basic data of villages and towns in 2008,the real erosion and equivalent pollution loads of 7 pollution sources in Pengxi River in the Three Gorges Reservoir Region were imputed by using the method of checklists.The 53 administrative districts in Pengxi River region were divided into 5 areas according to the results of cluster analysis and equivalent pollution loads.The main nutrients were total nitrogen,total phosphorus,ammonia nitrogen,and the main pollution sources were farmland runoff,rural life pollution,urban life pollution and livestock breeding pollution,with the contribution rate of 30.08%,19.53%,17.15%,16.29%.

On the basis of investigating the environmental information of centralized drinking water sources Chongqing City water quality classification,water quality eutrophic state,water quality healthy risk and water pollution of reservoir-based drinking water sources in Chongqing City were evaluated.And the analytical hierarchy process also was used to evaluate water security comprehensively.Finally,the water security status of reservoir-based drinking water sources of Chongqing City was achieved,which can provide a reference for protection and management of drinking water source.The results show that the water quality of reservoir-based drinking water sources is good,the rate of water sources security reaching standard is 97 percent.

Xiao-jiang, with a basin area of almost 5,276 km(2) and a length of 182.4 km, is located in the center of the Three Gorges Reservoir Area, and is the largest tributary of the central section in Three Gorges Reservoir Area, farmland accounts for a large proportion of Xiao-jiang watershed, and the hilly cropland of purple soil is much of the farmland of the watershed. After the second phase of water storage in the Three Gorges Reservoir, the majority of sub-rivers in the reservoir area experienced eutrophication phenomenon frequently, and non-point source (NPS) pollution has become an important source of pollution in Xiao-jiang Watershed. Because dissolved nitrogen and phosphorus non-point source pollution are related to surface runoff and interflow, using climatic, topographic and land cover data from the internet and research institutes, the Semi-Distributed Land-use Runoff Process (SLURP) hydrological model was introduced to simulate the complete hydrological cycle of the Xiao-jiang Watershed. Based on the SLURP distributed hydrological model, non-point source pollution annual output load models of land use and rural residents were respectively established. Therefore, using GIS technology, considering the losses of dissolved nitrogen and phosphorus in the course of transport, a dissolved non-point source pollution load dynamic model was established by the organic coupling of the SLURP hydrological model and land-use output model. Through the above dynamic model, the annual dissolved non-point source nitrogen and phosphorus pollution output as well as the load in different types were simulated and quantitatively estimated from 2001 to 2008, furthermore, the loads of Xiao-jiang Watershed were calculated and expressed by temporal and spatial distribution in the Three Gorges Reservoir Area. The simulation results show that: the temporal changes of dissolved nitrogen and phosphorus load in the watershed are close to the inter-annual changes of rainfall runoff, and the different land-use type distribution has great impacts on the spatial changes of dissolved nitrogen and phosphorus load in the watershed; The nitrogen and phosphorus load of different land-use types in size with descending order is, glebe and mixed land, paddy, grassland, urban land, forestland; however, for the phosphorus load, the unit area output load of glebe and mixed land is almost the same as for paddy fields; The output contribution of nitrogen and phosphorus pollution load from land-use accounts for 78%-85%, while the output contribution from livestock and poultry occupies 13%-20%. The established load model was verified by observation data, simulation results show that the established model is reasonable, simulation accuracy is higher.

The dynamic calculation methods of soil erosion modulus and sediment discharge modulus were brought forward by analyzing the key factors of yearly adsorbed load variation for Xiaojiang River Watershed in the Three Gorges Reservoir Area. The dynamic distribution model of annual adsorbed non-point source phosphorus load,based on the watershed characteristics of hydrology,geography and non-point source pollution,was built up. In view of space uncertainty characteristics for parameters in the model which are related to rainfall,soil,topography,vegetation,soil and water conservation,sediment delivery ratio and so on,the theory of blind number was introduced to deal with them. Applying GIS technology,the soil erosion modulus and adsorbed phosphorus load of Xiaojiang River Watershed from 1997 to 2007 were simulated and quantitatively calculated. The simulation results showed that the factor of rainfall erosion and runoff are the important factors which effect annual variation of adsorbed phosphorus pollution load,and that the space distribution of adsorbed non-point source phosphorus was closely related to the types of land-use,and the size of contribution rate was glebe and mix-ground,grassland,paddy field,woodland and urban land in turn. The validation revealed that the established model in which parameters were taken as the factors of blind number can be successfully applied for the assessment of the adsorbed non-point source pollution load for the watershed.

Dissolved nitrogen(DN)on land is washed away into waters by runoff, forming the pollution load of non-point source. Therefore, simulation of runoff from each land use or land cover type plays a very important part in estimated pollution load of dissolved nitrogen. Soil conservation service(SCS)runoff curve method was widely used for simulation of land runoff in popular non-point source pollution model, such as SWAT and AGNPS, etc. However, SCS model had a major limitation, that is, it was a statistical model for America, so there were some problems applying to Chinese basin directly. In this study, a physically-based and hydrological watershed model called Semi-Distributed Land Use-based Runoff Processes(SLURP)hydrological model, was used to simulate runoff from each land use or land cover type in order to estimate the DN load. Taking the Jialing River Basin as a research case, the DN model was formed. Considering the DN loss during the transport process from land to waters, a coefficient of transport loss was introduced in the DN model, and its statistical equation was educed by the monitoring data. Consequently, by using DN model and SLURP model, the spatial distribution of output capacity of the basin DN pollution was simulated, and the DN pollution load at the watershed outlet from1990 to 2005 was estimated by means of GIS. The results indicated that pollution in Fujiang River sub-basin which mainly consisted of dry farmland and paddy field was the most serious, and the followings were the subbasin of downstream watershed of Qujiang River and Xihanshui River sub-basin. The annual average DN load in the basin was so high that it reached 35 726 t·a-1 from 1990 to 2005 and accounted for about 32% of the total nitrogen load at the watershed outlet.