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91.
为推动资源与生态环境遥感监测数据的应用与服务,为国家、相关行业管理决策和社会公众提供有价值的信息,需要在资源与生态环境遥感监测成果数据基础上,开发数据管理与应用服务系统。本文从国家资源与生态环境建设的实际需求出发,结合国土资源部实施的环北京地区资源与生态环境遥感监测成果,探讨资源与生态环境遥感监测数据管理与应用服务的技术解决方案,搭建资源与生态环境遥感监测数据管理与应用服务技术平台,并实现网络环境下对资源与生态环境监测形成的各种类型数据的集成化管理。  相似文献   
92.
用逐步回归预测棉铃虫发生期和发生量   总被引:3,自引:0,他引:3  
收集了1973年至2000年的气象,农作物、棉铃虫虫害等196年因子,以运城、汾阳和临汾为山西省代表站,利用最优二分割法把发生量分为10级,5级和不分级3种情况;使用逐步回归计算了219个模型,从中选出27个棉铃虫二、三代发生期,发生量最优模型,在农气服务中应用,预报准确率为95%,效果良好。  相似文献   
93.
用快中子活化法测定了安徽凤阳和张八岭地区朱顶、毛山和上成3个金矿床第一阶段晚期和第二阶段的含金石英脉,石英的阶段加热40Ar/39Ar坪年龄值域为(116.1±0.6~118.3±0.5)Ma,分别与其最小视年龄和等时线年龄接近.坪年龄、最小视年龄和等时线年龄3种年龄值域为(113.4±0.4~118.3±0.5)Ma,可以作为石英的形成年龄域. 根据含金石英脉和围岩的空间关系,该年龄值域作为石英脉金矿的形成年龄是合理可靠的.金矿床形成于早白垩世阿普特期,与此时郯庐断裂带略带右行走滑正断层活动一致.  相似文献   
94.
微波作用下化学助剂在细粉煤脱水中的应用研究   总被引:2,自引:0,他引:2  
崔平  朱静  王知彩 《矿物学报》2002,22(4):375-378
探讨了在微波加热条件下加入表面活性剂和溶剂油等有机溶剂对脱水效果的影响,力求找出其中的脱水规律。结果表明:微波脱水效果明显,同时,表面活性剂能够大大降低滤饼含湿量,而且非离子表面活性剂的效果比阳离子、阴离子好,柴油也能促进粉煤的脱水。  相似文献   
95.
The Skidaway River estuary is a tidally-dominated subtropical estuary in the southeastern USA surrounded by extensiveSpartina salt marshes. Weekly smapling at high and low tide began in 1986 for hydrography, nutrients, chlorophylla, particulate matter, and microbial and plankton biomass and composition; hydrographic and nutrient data during 1986–1996 are reported here. Salinity varied inversely with river discharge and exhibited variability at all time scales but with no long-term trend. Water temperature typically ranged over 25°C and was without apparent long-term frend. Seasonal cycles in concentrations of NO3, NH4, PO4, Si(OH)4, and DON were observed, with annual maxima generally occurring in late summer. Superimposed on seasonal cycles, all five nutrients exhibited steady increases in minimum, mean, and maximum concentrations; mean concentrations increased c. 50–150% during the decade. Nutrient concentrations were highly correlated with water temperature over the ten-year period, but weakly related to salinity and discharge. Nutrients were strongly correlated with one another, and the relative ratios among inorganic nutrients showed little long-term trend. Correlations among temperature and nutrient concentrations exhibited considerable inter-annual variability. Major spikes in organic and inorganic nutrient concentrations coincided with significant rainfall events; concentrations increased hyperbolically with rainfall. Although pristine compared to more heavily impacted waterways primarily outside the region, residential development and population density have been increasing rapidly during the past 15–20 years. Land use is apparently altering nutrient loading over the long-term (months-years), and superimposed on this are stochastic meteorological events that accelerate these changes over the short term (days-weeks).  相似文献   
96.
Fuzzy neural network models for liquefaction prediction   总被引:1,自引:0,他引:1  
Integrated fuzzy neural network models are developed for the assessment of liquefaction potential of a site. The models are trained with large databases of liquefaction case histories. A two-stage training algorithm is used to develop a fuzzy neural network model. In the preliminary training stage, the training case histories are used to determine initial network parameters. In the final training stage, the training case histories are processed one by one to develop membership functions for the network parameters. During the testing phase, input variables are described in linguistic terms such as ‘high’ and ‘low’. The prediction is made in terms of a liquefaction index representing the degree of liquefaction described in fuzzy terms such as ‘highly likely’, ‘likely’, or ‘unlikely’. The results from the model are compared with actual field observations and misclassified cases are identified. The models are found to have good predictive ability and are expected to be very useful for a preliminary evaluation of liquefaction potential of a site for which the input parameters are not well defined.  相似文献   
97.
In east Asia, acidic gases derived from fossil fuel combustion have increased in the past decades. On the other hand, the Asian dust, also called Kosa (yellow sand) is transported following windstorms from arid lands in the Asian continent. Many researchers have been interested in the reaction between acidic aerosols and Kosa aerosols as well as the long-range transport of these emissions. To investigate the characteristics of chemical components in precipitation on a long-term basis over Japan, precipitation was sequentially collected from April 1984 to March 1997 at Kanazawa located near the coast of the Sea of Japan. Precipitation samples were collected at 1 mm intervals for the first 5 mm rainfall and all volume of rainwater after 6 mm for all precipitation events with an automatic wet only precipitation collector. According to the analyses of precipitation including Kosa aerosols during Kosa periods, the reaction in the air between Kosa and acidic components during the long-range transport was discussed.  相似文献   
98.
The paper describes Western Australian examples and causes of land degradation. It outlines shortcomings in the methodologies used to rehabilitate these areas. From this a protocol is suggested for an ‘holistic’ approach to land rehabilitation.  相似文献   
99.
Based on energy balance equation and mass transfer equation, a general model to estimate actual evaporation from non-saturated surfaces was derived. Making use of two concepts, “relative evaporation” and “relative drying power”, a relationship was established to account for the departure from saturated conditions. Using this model, the actual evaporation (evapotranspiration) can be calculated without the need of potential evaporation estimation. Furthermore, the model requires only a few meteorological parameters that are readily and routinely obtainable at standard weather stations. Based on nearly 30 years data of 432 meteorological stations and 512 hydrological stations in China, in combined with GIS, nine typical river basins were selected. Using the data of the selected river basins, the model was tested. The results show that the actual evaporation rate can be estimated with an error of less than 10% in most areas of China, except few years in the Yellow River Basin.  相似文献   
100.
试论少数民族地区的生态化旅游开发   总被引:6,自引:7,他引:6  
简王华 《干旱区地理》2003,26(3):286-290
生态化旅游开发是有别于传统的旅游开发的一种可持续开发与发展的理念,它追求的是生态、社会和经济综合效益的最大化,应该成为旅游开发与旅游业发展的主要方向。民族地区的旅游开发具有特定的区域生态特征。其生态化旅游开发的核心问题是旅游环境容量的确定与旅游环境的保护、民族特色与民族文化的弘扬以及注重旅游经济发展过程中旅游业的拉动效应及其依托性之间的关系处理等。  相似文献   
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