介绍了汽油 -液化石油气 (L PG)两用燃料发动机空燃比的调节和作者研制成功的无混合器式双蒸发器 L PG供气系统。该供气系统取消了 L PG发动机惯用的混合器 ,在原机双腔化油器的主、副腔喉管处钻孔 ,接入 L PG主供气系和 L PG加浓系 ,...介绍了汽油 -液化石油气 (L PG)两用燃料发动机空燃比的调节和作者研制成功的无混合器式双蒸发器 L PG供气系统。该供气系统取消了 L PG发动机惯用的混合器 ,在原机双腔化油器的主、副腔喉管处钻孔 ,接入 L PG主供气系和 L PG加浓系 ,从而取消了混合器 ,解决了全负荷时动力性与部分负荷时燃料经济性、排放之间的矛盾 ,取得了良好的效果。用该系统改装的汽油 - L PG两用燃料发动机 ,在燃用汽油时性能无任何变化 ,燃用 L PG时取得了动力性、燃料经济性和排放指标俱佳的效果。展开更多
For reasons of simplicity, the most commonly used hydrological models are based on the Soil Conservation Service Curve Number （SCS-CN） model, which is probably a good choice for the estimation of runoff on the Loess...For reasons of simplicity, the most commonly used hydrological models are based on the Soil Conservation Service Curve Number （SCS-CN） model, which is probably a good choice for the estimation of runoff on the Loess Plateau of China; however, the high spatial heterogeneity, mainly caused by a fragmented landform and variations in soil type, may limit its applicability to this region. Therefore, applicability of the SCS-CN model to a small watershed, Liudaogou on the plateau, was evaluated and the most appropriate initial abstraction ratio （I~/S） value in the model was quantified by the inverse method. The results showed that the standard SCS-CN model was applicable to the estimation of runoff in the Liudaogou watershed and the model performance was acceptable according to the values of relative error and Nash-Sutcliffe efficiency. The most appropriate Ia/S value for the watershed was 0.22 because with this modified Ia/S value, the model performance was slightly improved. The model performance was not sensitive to the modification of the Ia/S value when one heavy rainfall event （50.1 mm） was not considered, which implied that the model, using a standard Ia/S value, can be recommended for the Liudaogou watershed because single rainfall events exceeding 50 mm seldom occurred in that region. The runoff amount predicted for the Liudaogou watershed by the SCS-CN model, using the modified Ia/S value, increased gradually with increasing rainfall when rainfall values were lower than 50 mm, whereas the predicted amount increased rapidly when the rainfall exceeded 50 mm. These findings may be helpful in solving the problem of serious soil and water loss on the Loess Plateau of China.展开更多
文摘介绍了汽油 -液化石油气 (L PG)两用燃料发动机空燃比的调节和作者研制成功的无混合器式双蒸发器 L PG供气系统。该供气系统取消了 L PG发动机惯用的混合器 ,在原机双腔化油器的主、副腔喉管处钻孔 ,接入 L PG主供气系和 L PG加浓系 ,从而取消了混合器 ,解决了全负荷时动力性与部分负荷时燃料经济性、排放之间的矛盾 ,取得了良好的效果。用该系统改装的汽油 - L PG两用燃料发动机 ,在燃用汽油时性能无任何变化 ,燃用 L PG时取得了动力性、燃料经济性和排放指标俱佳的效果。
基金Supported by the National Natural Science Foundation of China (No.41001156)the Beijing Novel Program, China (No.2009B25)+1 种基金the Beijing Municipal Natural Science Foundation, China (No.8102015)the Open Fund of the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau of China (No.10501-295)
文摘For reasons of simplicity, the most commonly used hydrological models are based on the Soil Conservation Service Curve Number （SCS-CN） model, which is probably a good choice for the estimation of runoff on the Loess Plateau of China; however, the high spatial heterogeneity, mainly caused by a fragmented landform and variations in soil type, may limit its applicability to this region. Therefore, applicability of the SCS-CN model to a small watershed, Liudaogou on the plateau, was evaluated and the most appropriate initial abstraction ratio （I~/S） value in the model was quantified by the inverse method. The results showed that the standard SCS-CN model was applicable to the estimation of runoff in the Liudaogou watershed and the model performance was acceptable according to the values of relative error and Nash-Sutcliffe efficiency. The most appropriate Ia/S value for the watershed was 0.22 because with this modified Ia/S value, the model performance was slightly improved. The model performance was not sensitive to the modification of the Ia/S value when one heavy rainfall event （50.1 mm） was not considered, which implied that the model, using a standard Ia/S value, can be recommended for the Liudaogou watershed because single rainfall events exceeding 50 mm seldom occurred in that region. The runoff amount predicted for the Liudaogou watershed by the SCS-CN model, using the modified Ia/S value, increased gradually with increasing rainfall when rainfall values were lower than 50 mm, whereas the predicted amount increased rapidly when the rainfall exceeded 50 mm. These findings may be helpful in solving the problem of serious soil and water loss on the Loess Plateau of China.
