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471.
A. Rango J. Foster V. V. Salomonson 《Journal of the American Water Resources Association》1975,11(6):1245-1256
ABSTRACT: ERTS-1 satellite imagery has been evaluated as a means of providing useful watershed physiography information. From these data physiographic parameters such as drainage basin area and shape, drainage density, stream length and sinuosity, and the percentage of a watershed occupied by major land use types were obtained in three study areas. The study areas were: (1) Southwestern Wisconsin; (2) Eastern Colorado; and (3) portions of the Middle Atlantic States Using ERTS-1 imagery at 1:250,000 and 1:100,000 scales it was found that drainage basin area and shape and stream sinuosity were comparable (within 10%) in all study areas to physiographic measurements derived from conventional topographic maps at the same scales Land use information can be usefully extracted for watersheds as small as 30 mi2(78 km2) in area. Improved drainage network and density information is obtained from ERTS-1 imagery in dissected areas such as Southwestern Wisconsin, but in heavily vegetated areas (Middle Atlantic States) or areas with little physical relief (Eastern Colorado) low order streams are difficult to detect and the derived drainage densities are significantly smaller than those obtained from standard maps. It is concluded that ERTS-1 imagery can be employed to advantage in mean annual runoff prediction techniques and in providing or maintaining land use information used in the calibration and operation of watershed models. 相似文献
472.
基于GM(1,1)模型的铁路行车事故预测 总被引:1,自引:5,他引:1
罗金保 《中国安全科学学报》2004,14(6):14-16
铁路行车事故的发生具有偶然性 ,但可利用预测理论的方法加以预测。笔者简述了灰色理论中GM(1,1)预测模型的建模过程和精度检验的方法及步骤 ,在某铁路分局 1995~ 2 0 0 2年间的铁路行车事故统计的基础上 ,应用GM(1,1)预测模型预测了该铁路分局 2 0 0 4年的铁路行车事故发生趋势 ,经精度检验表明 ,模型的精度等级合格 ,其预测结果为铁路行车事故的防范和降低事故损失提供了指导和科学依据。 相似文献
473.
Albert L. Juhasz Euan Smith Julie Smith Ravendra Naidu 《Water, Air, & Soil Pollution: Focus》2003,3(3):233-242
A two-phase soil washing biosorption process was developed for the remediation of p,p-DDT-contaminated soil. The process involved desorption of contaminants from soil using dilute primary alcohols (40% 1-propanol) followed by contaminant removal from cosolvent solutions using fungal biosorption. Bench scale remediation studies were preformed to simulate ex situ (recycling experiment) or in situ (soil column study) treatment strategies. Both systems were effective at cleaning the soil to below Australian regulatory p,p-DDT levels. After 50–80 hours of soil washing, over 93% of p,p-DDT was removed from the soil(990 mg kg-1 to <65 mg kg-1) using either of these methods.p,p-DDT was removed from the cosolvent phase by sorption onto the fungal biomass. This resulted in only low levels of p,p-DDT remaining in the cosolvent solution(<1.5 mg l-1). The application of both treatment strategies resulted in the rapid clean up of p,p-DDT-contaminated soil and the potential to recycle cosolvent solutions. The ability to recycle cosolvent solutions provides a mechanism for cost reductions of the remediation strategy. 相似文献
474.
N—N—二(1—甲基—庚基)乙酰胺萃取苯酚的动力学研究 总被引:3,自引:0,他引:3
用恒界面池法研究了N,N-二(1-甲基-庚基)乙酰胺(DMHAA,N503)萃取苯酚的动力学,试验表明,萃取速率随水相苯酚浓度,有机相N503浓度的提高而增加,当水相pH值≥10.5时,萃取速度明显下降,萃取反应的表观活化能为14.3kJ·mol^-1,萃取过程属扩散控制,水相中萃酚向两相界面的扩散是萃取速度的控制步骤。 相似文献
475.
本文报道在0.1M亚硝酸钠,1.5×10~(-3)M的1,2-丙二胺,pH9.0—9.5底液中铬在—1.76伏处(对饱和甘汞电极)产生-催化波,测定范围在0.1ng/ml内,铬的浓度与导数波高成良好线性关系,测定下限为8×10~(-10)M(相当于0.04ng/ml)。经实验证明,在1,2-丙二胺-亚硝酸盐或硝酸盐两体系中,铬都在—1.76伏处产生催化波,因此,可认为铬的催化机理可能与文献[3]报道的在CyDTA-NO_3体系中三价铬产生催化波的机理相似即: Cr~(6 ) 3e—→Cr~(3 ); Cr~(3 ) y—→Cr~(3 )—y; Cr~(2 )—y e—→C~(2 )—y; Cr~(2 )—y NO_3~—→Cr~(3 )—y No_2~-其中:y代表1,2-丙二胺。将自来水进行简单的前处理后,可以直接应用本法测定水中六价、三价铬的含量以及水中的总铬量。 相似文献
476.
对GM(1,1)模型经差分形式化及令定写成直线方程形式。据最小二乘法原理,原方程的参数辨识可借助线性回归方法来实现。从而使GM(1,1)模型的应用更显普及和实用化。 相似文献
477.
Climatic change will result in great changes in vegetation. In this paper, a biogeographical model, the BIOME1, was used to
predict potential vegetation distribution in China under climate change. Firstly, the BIOME1 was validated according to the
climate–vegetation relationships in China. Kappa statistics showed that the validated BIOME1 was able to capture the geographical
patterns of vegetation more accurately. Then, the validated BIOME1 was used to predict the distribution of vegetation of China
under two climatic scenarios produced by a Regional Circulation Model, RegCM2/CN. The simulation results showed obvious northward
shifts of the boreal, temperate deciduous and evergreen and tropical forests, a large expansion of tropical dry forest/savanna
and reduction of tundra on the Tibetan Plateau. Three vulnerable regions sensitive to climate changes are pointed out, i.e.,
Northern China, the Tibetan Plateau and Southwestern China (mainly Hengduan Mountains in Yunnan Province and west of Sichuan
Province). In recent decades, China has experienced dramatic industrialization and population growth, which exert strong pressure
on the environment of China. The consequences of climate changes warrant more attention for maintaining a sustainable environment
for China. 相似文献
478.
研究了用1-(2,6-二氯-4-硝基苯)-3-(4-硝基苯)-三氮烯(DCNPNPT)分光光度法快速直接测定锌的方法。在表面活性剂TritonX-15的存在下,pH=9.5~10.5的Na2B4O7-NaOH介质中,DCNPNPT与锌( )可生成1∶3的橙黄色络合物。最大吸收波长为445nm,同时在535nm配合物有一最大负吸收,建立以535nm为参比波长,445nm为测定波长的双峰双波长法进行测定,表观摩尔吸光系数可达1.12×105L/(mol·cm)。用拟定的方法测定矿山废水中的锌,与原子吸收法测定的结果十分吻合,结果令人满意。 相似文献
479.
In this paper, a mathematical model is developed for net methane emission from rice fields by coupling methane production
model with methane oxidation model. Several dynamical regimes were formed through qualitative analysis of the model, and corresponding
dynamic features were interpreted through emission indices. Sensitivity of the model is discussed under the effects of temperature
and oxygen concentration in methanogenic and methane oxidation phases, respectively, and interpreted by defining an index;
in addition, control parameters are identified and their threshold limits defined. The out-busting emission tendency of methane
is considered separately and a forcing strategy was defined to force emission level towards zero in the long term. Lastly,
a complete control strategy is proposed for reducing methane emission. 相似文献
480.