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11.
Chih-Chiang Lu Chu-Hui Chen Tian-Chyi J. Yeh Cheng-Mau Wu I-Fang Yau 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,20(1-2):6-22
Typhoons and storms have often brought heavy rainfalls and induced floods that have frequently caused severe damage and loss
of life in Taiwan. Our ability to predict sewer discharge and forecast floods in advance during storm seasons plays an important
role in flood warning and flood hazard mitigation. In this paper, we develop an integrated model (TFMBPN) for forecasting
sewer discharge that combines two traditional models: a transfer function model and a back propagation neural network. We
evaluated the integrated model and the two traditional models by applying them to a sewer system of Taipei metropolis during
three past typhoon events (NARI, SINLAKU, and NAKR). The performances of the models were evaluated by using predictions of
a total of 6 h of sewer flow stages, and six different evaluation indices of the predictions. Finally, an overall performance
index was determined to assess the overall performance of each model. Based on these evaluation indices, our analysis shows
that TFMBNP yields accurate results that surpass the two traditional models. Thus, TFMBNP appears to be a promising tool for
flood forecasting for the Taipei metropolis sewer system.
For publication in Stochastic Environmental Research and Risk Analysis. 相似文献
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13.
海水入侵水化学指标及侵染程度评价研究 总被引:26,自引:1,他引:25
选择Cl^,M、Br^-,rHCO3/rCl及SAR5项水化学要素作为综合判断海水入侵的指标:染程度划分为4级;确定了各项指标入程度的等级范围。入侵程度的衡理采用模糊数学综合判模型。 相似文献
14.
陶湾磷矿是近年来在锦屏、新浦磷矿附近新发现并勘探的中型矿床,其可选性指标通过与相邻老矿山类比确定。近期浅部坑采试选表明,勘探期间所定陶湾磷矿选矿指标是合理、可行的。 相似文献
15.
Arctic sea-ice motion and its relation to pressure field 总被引:5,自引:0,他引:5
Daily Arctic sea-ice motion maps during the winter seasons (December–March) from December 1988 to March 2003 derived from
NSCAT, QuikSCAT, SSM/I, and AMSRE data by a wavelet analysis method have been merged with those derived from buoy data. These
merged sea-ice motion data have been used to study the circulation regimes and winter-to-winter variability of Arctic sea-ice
motion. The relation between sea-ice motion and the pressure field in the Arctic Ocean was also studied by applying Principal
Component Analysis (PCA) to the monthly merged sea-ice motion data and the monthly pressure field data from IABP. The mean
Arctic sea-ice motion map of the 15 winter seasons has two distinct features: the Beaufort Gyre and a cyclonic circulation
system in the Eurasian Basin, which moves ice from the Laptev Sea to Fram Strait. The strengths and sizes of the two features
change from one winter season to another. Seasons with a strong or normal Beaufort Gyre alternate with seasons with a weak
or no Beaufort Gyre every one to three seasons. The principal components of the first two modes of PCA of the monthly sea-ice
motion are closely correlated with their counterparts of the monthly pressure field in the Arctic Ocean. The mode-one components
of these two anomalies alternate between anticyclonic and cyclonic circulation systems. The correlation between Arctic Oscillation
indexes and the principal components of the first mode of PCA of the monthly Arctic sea-ice motion is low but statistically
significant. 相似文献
16.
南极普里兹湾及其邻近海域水团研究 总被引:3,自引:3,他引:0
普里兹湾及其邻近海域是中国南大洋调查研究的传统优势海域与重点区域。围绕夏季表层水、冬季水、陆架水、绕极深层水、南极底层水、普里兹湾底层水、冰架水等研究海区主要水团的特征和分布,总结了前人在南极普里兹湾及其邻近海域基于调查资料开展的水团研究中所取得的成果。研究表明,前人在对陆架水的示性指标界定上,将陆架水是否区分为高盐陆架水和低盐陆架水存在较大争议,在高盐陆架水和普里兹湾底层水的定义上存在重叠;目前尚没有证据表明绕极深层水向南可以伸展到普里兹湾的陆架区域,也没有发现在普里兹湾附近海域生成南极底层水的直接证据。 相似文献
17.
Winter conditions play an important role for the largest lake in Europe—Lake Ladoga. The ice cover lasts for 171 ± 3 days on average from the early November until the mid‐May. We investigated the ice regime of Lake Ladoga using a constructed ice database of aircraft surveys and satellite images. More than 1250 surveys of the lake's ice cover from 1943 to 2010 were collected and analysed to determine mean and extreme ice conditions for winters of different types of severity. The time series of ice cover percentage over the lake was plotted. On average, 18 observational ice charts were made every winter. Individual ice phenology records show considerable year‐to‐year variation. For this reason, records typically have been combined and analysed as groups (categories). Extremely cold winters were determined as winters with complete ice cover that lasts more than three months which is approximately 90% quartiles from all winters with complete ice cover. The lake surface was completely covered with ice for more than three months during 5 seasons. Extremely warm winters when the maximum ice cover was less than 70% of the lake area occurred during 5 seasons as well. A basic relationship between the winter severity as winter maximum of accumulated freezing degree‐days (AFDD) and the earlier derived Relative Ice Cover Index (RICI) was established. We have used teleconnection indices such as North Atlantic Oscillations (NAO) and Arctic Oscillation (AO) for the period from October to May for estimation of different types of Lake Ladoga's ice conditions. The AO index in winter months and local winter maximum of AFDD explained much of the interannual variation in ice cover. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
18.
19.
机械钻速、钻头进尺和每米钻探成本通常称之为是钻探工程的主要技术经济指标。这些技术经济指标均与选用的钻头、所用钻进规程参数和操作技术紧密相关。选用的钻头应与所钻地层的硬度、研磨性(可钻性)相适应。操作技术主要取决于司钻人员的技术、经验和水平。而钻进规程参数的选取和确定及其合理配合则是非常重要的一个因素,不可忽视。提出了临界钻进规程的概念。临界规程是一条红线,不可逾越,否则就会发生事故。正常钻进规程时,钻压和钻头转速应该合理配合,冲洗液量宜保证岩粉处于正常规程状态,以得到理想的钻探工程技术经济指标。建议根据功率表读数变化来调整钻压和钻头转速的合理配合,利用流量计监控孔底的冲洗液数量,严格控制临界规程的形成,把经验打钻和科学打钻结合起来。 相似文献
20.
基于GIS的陕北景观结构 总被引:7,自引:1,他引:6
以陕西土地利用现状图作为数据基础,应用Arc/Info和Arc/view等GIS专业软件,对陕北地区的景观进行了分类,并形成了景观分类图。利用景观格局分析软件FRAGSTATS,在斑块类型和景观两个水平上计算了相应的参数和景观指数,定量揭示了整个区域的景观格局与类型特征。为进行深入研究和揭示生态过渡地带生态过程奠定了基础。 相似文献