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珠江三角洲公路系统震害预测 总被引:1,自引:0,他引:1
在收集整理珠江三角洲地区几条主要干线道路上的桥梁和场地害预测资料的基础上,利用我们建立的基于人工神经元网络的桥梁震害预测方法,对这几条干线道路上的桥梁进行了震害预测。并在此基础上,对这几条干线道路系统的车通性进行了分析。 相似文献
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广西地区的水系展布与活动断裂及新构造应力场的关系 总被引:3,自引:0,他引:3
对广西以及邻区的部分河流进行了统计分析,认为广西水系较好地反映了广西断裂的展布和活动性,一些原称隐伏断裂应当看成活动断裂,文章还对水系统计法进行了讨论,指出该方法在理论上存在某些缺陷,在实际操作上也存在较多问题。 相似文献
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沉积盆地岩浆侵入的热模拟 总被引:15,自引:1,他引:15
沉积盆地中岩浆的侵入会导致盆地地温史的变化,影响烃类成熟度,本文对沉积盆地中岩浆侵入过程进行了热模拟,分析了岩浆侵入对沉积盆地温度结构和成油窗的影响,在计算中,既考虑了岩浆凝固过程释放的潜热,又考虑了岩石比热,热导率随温度的变化对热模拟结果的影响,通过计算认识到:沉积盆地中侵入岩浆在垂直方向上的热扩散比水平方向热扩散更快,几公里大小的侵入体其热影响可以在时间上持续数百万年,在空间上扩散至十数公里, 相似文献
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中国大陆强震组的预测研究 总被引:1,自引:0,他引:1
地震活动图象无论在时间上还是在空间上都具有层层嵌套的自相似结构。我国大陆地区强震预报的基本程式是,在空间上由大到小,在时间上由长到短,逐步逼近地进行。与地震系统的层次结构大体相应。但是当对各个重点危险区作判定时却是彼此孤立进行的。对于已发生的强震的意义缺乏足够分析。本文根据强震成组的基本特点及前兆异常中存在地震组异常的基本事实,提出了地震组预测的原则和基本方法。 相似文献
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本文从地球物理场出发,通过严密的数学物理推导,提出了磁力测深公式,并导出了著名的重力测深公式的更一般表达式。为了得到更为精确的解,本文又提出了应用最优化理论的空间域迭代算法,并根据地球物理模型对于高斯优化法进行了改进,在算法上有所创新,使其在计算机上实现时算法简单,计算速度快。文中还列举了一些模型的实验结果,对磁力测深公式及迭代算法的有效性及可靠性进行了论证。用本文方法对实际资料的处理结果是令人满意的,证明该方法有一定的实用性。 相似文献
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Gtz Schroth Luciana Ferreira Da Silva Marc‐Andree Wolf Wenceslau Geraldes Teixeira Wolfgang Zech 《水文研究》1999,13(10):1423-1436
The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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M. N. French R. L. Bras W. F. Krajewski 《Stochastic Environmental Research and Risk Assessment (SERRA)》1992,6(1):27-45
A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities. 相似文献
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M. A. Kahn 《洁净——土壤、空气、水》2000,28(2):95-101
Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate. 相似文献
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