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581.
582.
W. Abtew J. Obeysekera G. Shih 《Journal of the American Water Resources Association》1993,29(2):179-188
ABSTRACT: Several methods have been developed to interpolate point rainfall data and integrate areal rainfall data from any network of stations. From previous studies, it can be concluded that models for spatial analysis of rainfall are dependent on topography, area of analysis, type of rainfall, and density of gauging network. The purpose of this study is to evaluate a set of six appropriate models for point and areal rainfall estimations over a 4000 square mile area in South Florida. In this study, a case of developing spatial continuity model for monthly rainfall from a database that had various lengths of records and missing data is documented. The spatial correlation and variogram models for monthly rainfall were developed. Six methods of spatial interpolation were applied and the results validated with historical observations. The results of the study indicate that the multiquadric, kriging, and optimal interpolation schemes are the best three methods for interpolation of monthly rainfall within the study area. The optimal and kriging methods have the advantage of providing estimates of the error of interpolation. The optimal interpolation method uses the spatial correlation function and the kriging method uses the variogram function. The two spatial functions are related. Either of the two methods provide good estimates of monthly point and areal rainfall in the study area. 相似文献
583.
With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant (WWTP) was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied. 相似文献
584.
Use of Maryland Biological Stream Survey Data to Determine Effects of Agricultural Riparian Buffers on Measures of Biological Stream Health 总被引:1,自引:0,他引:1
This study was undertaken to determine the importance of riparian buffers to stream ecology in agricultural areas. The original
Maryland Biological Stream Survey (MBSS) data set was partitioned to represent agricultural sites in Maryland's Coastal Plain
and Piedmont regions. ANOVA, multiple linear regression (MLR), and CART regression tree models were developed using riparian
and site catchment landscape characteristics. MBSS data were both stratified by physiographic region and analyzed as a combined
data set. All models indicated that land management at the site was not the controlling factor for fish IBIs (FIBI) at that
site and, hence, using FIBI to evaluate site-scale factors would not be a prudent procedure. Measures of instream habitat
and location in the stream network were the dominant explanatory factors for FIBI models. Both CART and MLR models indicated
that forest buffers were influential on benthic IBIs (BIBI). Explanatory variables reflected instream conditions, adjacent
landscape influence, and chemistry in the Coastal Plains sites, all of which are relatively site specific. However, for Piedmont
sites, hydrologic factors were important, in addition to adjacent landscape influence, and chemistry. Both Coastal Plain and
Piedmont CART models identified several hydrologic factors, emphasizing the dominant control of hydrology on the physical
habitat index (PHI). Riparian buffers were a secondary influence on PHI in the Coastal Plain, but not in the Piedmont. Between
40% and 70% of the variation in FIBI, BIBI, and PHI was explained by the “easily obtainable” variables available from the
MBSS data set. While these are empirical results specific to Maryland, the general findings are of use to other locations
where the establishment of forest buffers is considered as an aquatic ecosystem restoration measure. 相似文献
585.
利用作者研究的统计箱模式,模拟分析了1990年的硫沉降及其来源。结果表明,SO2浓度分布与排放源有着密切的关系,而SO2-4浓度分布受气象场的影响较明显;干沉降作用对大气中的SO2是一个重要的清除过程,SO2-4在大气中的清除主要通过湿沉降过程实现;硫沉降污染主要集中在华北大部,长江中下游的江浙地区、川贵部分地区和华中地区的武汉、长沙等地附近;直辖市的排硫大部分传输沉降到相邻的省份,其它省份的排硫一半左右沉降在本省,大约三分之一的排硫输送到相邻的省份。 相似文献
586.
587.
588.
为了对高层建筑电气火灾隐患排查进行定量化分析,采用解释结构模型构建高层建筑电气火灾隐患因子的复杂逻辑模型;在利用德尔菲法确定隐患因子初始概率的基础上,经过交叉影响分析法求解交叉影响概率矩阵;引入马尔科夫链修正各隐患因子交叉影响后的概率,得到火灾隐患因子的稳态概率矩阵。研究结果表明:各隐患因子的马尔科夫链校正概率比德尔菲法测定的初始概率更加准确,该计算排序结果可明确高层电气火灾隐患排查和管控的重点。 相似文献
589.
Christopher J. Woltemade Timothy W. Hawkins Claire Jantz Scott Drzyzga 《Journal of the American Water Resources Association》2020,56(3):507-527
Changing climate and land cover are expected to impact flood hydrology in the Delaware River Basin over the 21st Century. HEC‐HMS models (U.S. Army Corps of Engineers Hydrologic Engineering Center‐Hydrologic Modeling System) were developed for five case study watersheds selected to represent a range of scale, soil types, climate, and land cover. Model results indicate that climate change alone could affect peak flood discharges by ?6% to +58% a wide range that reflects regional variation in projected rainfall and snowmelt and local watershed conditions. Land cover changes could increase peak flood discharges up to 10% in four of the five watersheds. In those watersheds, the combination of climate and land cover change increase modeled peak flood discharges by up to 66% and runoff volumes by up to 44%. Precipitation projections are a key source of uncertainty, but there is a high likelihood of greater precipitation falling on a more urbanized landscape that produces larger floods. The influence of climate and land cover changes on flood hydrology for the modeled watersheds varies according to future time period, climate scenario, watershed land cover and soil conditions, and flood frequency. The impacts of climate change alone are typically greater than land cover change but there is substantial geographic variation, with urbanization the greater influence on some small, developing watersheds. 相似文献
590.
张广胜 《中国安全生产科学技术》2020,16(3):164-169
为有效解决应急物资调运决策问题,提高应急物资利用率。总结应急物资调运基本流程、管理方法及存在问题,分析应急物资调运系统动静态资源、灾害分布及优先级等因素,借鉴动态调配 Multi Agent方法研究应急救援保障部门间协同作用,对应急物资调运系统供需路径与救援时效进行分析,构建应急物资调运系统高效、及时、低成本的动态调度模型,同时基于多源时间最短路径问题以及Floyd Warshall算法对模型进行求解仿真,得出应急物资最优调运路径和参与调配储存点组合。结果表明:动态调运决策模型可从备选集合中快速搜索应急调运所需最佳方案,能为应急救援提供更加可靠的保障。 相似文献