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排序方式: 共有491条查询结果,搜索用时 31 毫秒
71.
Cyanobacterial blooms occur frequently in lakes due to eutrophication. Although a number of models have been proposed to forecast algal blooms, a good and applicable method is still lacking. This study explored a simple and effective mathematical-ecological model to evaluate the growth status and predict the population dynamics of Microcystis blooms. In this study, phytoplankton were collected and identified from 8 sampling sites in Chaohu Lake every month from July to October, 2010. The niche breadth and niche overlap of common species were calculated using standard equations, and the potential relative growth rates of Microcystis were calculated as a weighted-value of niche overlap. In July, the potential relative growth rate was 2.79 (a.u., arbitrary units) but then rapidly declined in the following months to -3.99 a.u. in September. A significant correlation (R=0.998, P<0.01) was found in the model between the net-increase in biomass of Microcystis in the field and the predicted values calculated by the niche model, we concluded that the niche model is suitable for forecasting the dynamics of Microcystis blooms. Redundancy analysis indicated that decreases in water temperature, dissolved oxygen and total dissolved phosphorus might be major factors underlying bloom decline. Based on the theory of community succession being caused by resource competition, the growth and decline of blooms can be predicted from a community structure. This may provide a basis for early warning and control of algal blooms. 相似文献
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天津市地震前兆台网的运行监控与维护管理 总被引:8,自引:0,他引:8
介绍天津市地震前兆台网的基本概况以及前兆台网部的职责任务;阐述仪器设备运行监控、观测数据质量监控的方式与方法;总结在仪器设备、技术系统维护过程中解决的一些关键技术问题;最后提出了关于仪器和软件系统的一些问题与建议。 相似文献
75.
在日常工作当中,由于卫星地面传输设备故障造成的数据传输中断以及解决办法,同时就卫星信号地面传输设备的维护办法做出了详细总结,从而实现卫星测震台低故障率,为地震速报工作提供有力保障。 相似文献
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北祁连西段镜铁山式铜矿预测要素及预测模型 总被引:2,自引:0,他引:2
在北祁连镜铁山地区,近年来发现了与中元古界条带状铁建造有关的破碎带蚀变岩型铜矿,如桦树沟铜矿床和柳沟峡铜矿床。分析了铜矿床的预测要素:矿源层为含铜条带状铁建造;有利于矿质活化的构造为透入性构造裂隙;热源为壳源岩浆活动;储矿构造为构造破碎蚀变带。建立了镜铁山式铜矿资源潜力预测的经验公式,对预测区铜远景资源潜力、铁矿石量、透入性构造裂隙发育程度和热源参数的取值分别进行探讨。据此公式估算,整个北祁连西段镜铁山式铜矿的铜金属资源潜力为147.3万t,其中镜铁山矿田铜资源潜力可达约125万t。实地考察也发现了新的找矿有利地段,因此有必要继续加大找矿力度。 相似文献
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AbstractLittle is known about the salt intrusion behaviour in Malaysian estuaries. Study of salt intrusion generally requires large amounts of data, especially if 2-D or 3-D numerical models are used; thus, in data-poor environments, 1-D analytical models are more appropriate. A fully analytical 1-D salt intrusion model, which is simple to implement and requires minimal data, was tested in six previously unsurveyed Malaysian estuaries (Kurau, Perak, Bernam, Selangor, Muar and Endau). The required data can be collected during a single day of observations. Site measurements were conducted during the dry season (June–August 2012 and February–March 2013) near spring tide. Data on cross-sections (by echo-sounding), water levels (by pressure loggers) and salinity (by moving boat) were collected as model input. A good fit was demonstrated between the simulated and observed salinity distribution for all six estuaries. Additionally, the two calibration parameters (the Van der Burgh coefficient and the boundary condition for the dispersion) were compared with the existing predictive equations. Since gauging stations were only present in some nested catchments in the drainage basins, the river discharge had to be up-scaled to represent the total discharge contribution of the catchments. However, the correspondence between the calibration coefficients and the predictive equations was good, particularly in view of the uncertainty in the river discharge data used. This confirms that the predictive salt intrusion model is valid for the cases studied in Malaysia. The model provides a reliable, predictive tool, which the water authority of Malaysia can use for making decisions on water abstraction or dredging.
Editor D. Koutsoyiannis; Associate editor A. Fiori 相似文献
79.
《International Journal of Digital Earth》2013,6(5):421-433
Abstract Sources of heterogeneous geospatial data such as the elevation, the slope, the aspect, the water network and the current settlements related to the known Neolithic archaeological sites of Magnesia, are used in an attempt to confirm the existence and allow for the prediction of other archaeological sites using predictive modelling theory. Predictive modelling allows the update of the problem solving strategy as soon as new data layers are available. The Dempster–Shafer Theory also commonly referred to as evidential reasoning (ER) is used to compose probability maps of areas of archaeological interest from physiographical and historical data. The advantage of this theory is that the ignorance is quantified and used to compose the probability maps named as belief, plausibility and belief interval for the archaeological sites. The final digital probability maps show that the Neolithic archaeological sites can be detected in the prefecture of Magnesia. This research study forms a methodological tool for the prediction of new archaeological sites in other areas of archaeological interest according to the physiographical and historical characteristics of the archaeological period being examined. It also contributes to the digital earth modelling and archaeological site protection, one of the most critical and challenging global initiatives. 相似文献
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