The draft ratios for sizing the reservoirs can vary within a wide range (40% - 90% of the mean annual flow, MAF), depending upon the demands for water by various users, and environmental and ecological considerations....The draft ratios for sizing the reservoirs can vary within a wide range (40% - 90% of the mean annual flow, MAF), depending upon the demands for water by various users, and environmental and ecological considerations. The reservoir volumes based on the drought magnitude (DM) method were assessed at aforesaid draft ratios using monthly-standardized hydrological index (SHI) sequences of 10 Canadian rivers located in the Canadian prairies and northwestern Ontario. These rivers are typified by a high level of persistence lag-1 autocorrelation, ρ<sub>1m</sub> ≥ 0.50 and up to 0.94) and coefficient of variation (cv<sub>o</sub>) in the range of 0.42 to 1.48. The moving average (MA) smoothing of monthly SHI sequences formed the basis of the DM method for estimating reservoir volumes. The truncation or cutoff level in the SHI sequences was found as SHI<sub>x</sub> [=(α - 1)μ<sub>o</sub>/σ<sub>o</sub>], [(α - 1)μ<sub>o</sub>/σ<sub>max</sub>], or [(α - 1)μ<sub>o</sub>/σ<sub>av</sub>], where α (=0.40 to 0.90) is the draft ratio i.e. proportion of the MAF, μ<sub>o</sub> and σ<sub>o</sub> are the overall mean and standard deviation of the monthly flows, σ<sub>max</sub> is the maximum value of standard deviations and σ<sub>av</sub> the average of 12 monthly values. The failure probability levels (PF) were fixed at 5%, 2.5% and 0% (corresponding reliability of 95%, 97.5% and 100%). The study revealed that the coefficient of variation is the most important parameter that influences the reservoir size while the role of lag-1 autocorrelation (ρ<sub>1m</sub>) appears more pronounced at high draft ratios, α such as 0.90, 0.80 and 0.70 in increasing the reservoir size. The DM based method can be regarded as an alternative to Behavior analysis for sizing reservoirs at the desired probability of failure or reliability level.展开更多
为简化多层机织物的工艺设计,研发了多层机织物组织CAD。详细阐述了该系统的特点、数学模型,并以蜂巢组织为实例进行了说明。该系统采用Barland C++ Builder5.0语言编程,用开口图表示多层织物组织,并提出顺逆序投纬模式,适用于任意层数...为简化多层机织物的工艺设计,研发了多层机织物组织CAD。详细阐述了该系统的特点、数学模型,并以蜂巢组织为实例进行了说明。该系统采用Barland C++ Builder5.0语言编程,用开口图表示多层织物组织,并提出顺逆序投纬模式,适用于任意层数的机织物设计,能自动生成穿综图及纹板图。展开更多
文摘The draft ratios for sizing the reservoirs can vary within a wide range (40% - 90% of the mean annual flow, MAF), depending upon the demands for water by various users, and environmental and ecological considerations. The reservoir volumes based on the drought magnitude (DM) method were assessed at aforesaid draft ratios using monthly-standardized hydrological index (SHI) sequences of 10 Canadian rivers located in the Canadian prairies and northwestern Ontario. These rivers are typified by a high level of persistence lag-1 autocorrelation, ρ<sub>1m</sub> ≥ 0.50 and up to 0.94) and coefficient of variation (cv<sub>o</sub>) in the range of 0.42 to 1.48. The moving average (MA) smoothing of monthly SHI sequences formed the basis of the DM method for estimating reservoir volumes. The truncation or cutoff level in the SHI sequences was found as SHI<sub>x</sub> [=(α - 1)μ<sub>o</sub>/σ<sub>o</sub>], [(α - 1)μ<sub>o</sub>/σ<sub>max</sub>], or [(α - 1)μ<sub>o</sub>/σ<sub>av</sub>], where α (=0.40 to 0.90) is the draft ratio i.e. proportion of the MAF, μ<sub>o</sub> and σ<sub>o</sub> are the overall mean and standard deviation of the monthly flows, σ<sub>max</sub> is the maximum value of standard deviations and σ<sub>av</sub> the average of 12 monthly values. The failure probability levels (PF) were fixed at 5%, 2.5% and 0% (corresponding reliability of 95%, 97.5% and 100%). The study revealed that the coefficient of variation is the most important parameter that influences the reservoir size while the role of lag-1 autocorrelation (ρ<sub>1m</sub>) appears more pronounced at high draft ratios, α such as 0.90, 0.80 and 0.70 in increasing the reservoir size. The DM based method can be regarded as an alternative to Behavior analysis for sizing reservoirs at the desired probability of failure or reliability level.
