历史查询   



 没有找到相关例句 
 Shear lag coefficient in framed tube structures was put forward based on the equivalent continuous system method.According to the analysis of the main influence factors on shear lag such as structural height,plane shape,area of corner column,and the ratio of span to height,the valid ways to reduce shear lag were discussed.In order to make the shear lag effect minimum and take full of structural space overall function,the reasonable ratio of span to height was studied using the optimal principle,and the... Shear lag coefficient in framed tube structures was put forward based on the equivalent continuous system method.According to the analysis of the main influence factors on shear lag such as structural height,plane shape,area of corner column,and the ratio of span to height,the valid ways to reduce shear lag were discussed.In order to make the shear lag effect minimum and take full of structural space overall function,the reasonable ratio of span to height was studied using the optimal principle,and the reasonable section height and hole rate can be obtained.Some diagrams were given,and an example was taken to find that the shear lag coefficient became less obvious after the optimization.It is shown that this method is accurate and convenient enough for use during the preliminary stage of design.  基于等效连续化方法给出了框筒结构剪力滞系数,通过对结构高度、平面形状、角柱面积、跨高比等影响剪力滞的主要因素分析,探讨了减小剪力滞的有效方法。再利用优化原理,寻求梁柱的合理跨高比使得剪力滞效应达到最小,以便充分发挥框筒结构的空间整体性能,进而确定梁柱的合理截面高度及合理开洞率。给出了计算图表及计算步骤,并结合具体算例,验证了优化后的剪力滞系数较优化前明显减小。结果表明:该方法简单、实用,可供初步设计使用。  In order to choose the optimal model for water demand forecasting, a combined forecasting method based on the optimal principle was put forward. According to the characteristics of domestic water consumption time series data from 1988 to 2003 and the fitting accuracy of the model, appropriate models were chosen, then based on the optimal principle the optimal weight coefficients were obtained, and finally a combined forecasting model was set up, which mainly included regression analysis model,... In order to choose the optimal model for water demand forecasting, a combined forecasting method based on the optimal principle was put forward. According to the characteristics of domestic water consumption time series data from 1988 to 2003 and the fitting accuracy of the model, appropriate models were chosen, then based on the optimal principle the optimal weight coefficients were obtained, and finally a combined forecasting model was set up, which mainly included regression analysis model, grey model and BP neural network model. Two of the subareas were used as case studies. The mean relative error ( MRE) in the Luanhe subarea is just 1.91%, and that in the Ziyahe subarea is only 1.54%. Domestic water consumption in the Luanhe subarea is 6.15 × 108 m3 in 2010 and 7. 37 × 108 m3 in 2030, and that in the Ziyahe subarea is 8. 72 × 108 m3 in 2010 and 1. 27 × 109 m3 in 2030. The results show that the methodology improves prediction accuracy.  针对用水量预测组合模型的优选问题,根据海河流域19882003年生活用水量时间序列的具体变化特征和拟合精度进行组合模型初选,并引入最优组合原理,确定组合权系数．所用的预测模型主要有回归模型、灰色模型和BP神经网络模型．以滦河分区和子牙河分区为例,计算的平均相对误差(MRE)分别为1．91％和1．54％, 2010年生活用水量将分别达到6．15×108m3和8．72×108 m3,2030年将分别达到7．37×108 m3和1.27×109 m3．结果表明,该方法提高了预测精度,可为水资源规划和管理提供依据．  
相关查询  


