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Influence of Different Transition Modes on the Performances of a Hydraulic Turbine 被引量:1
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作者 Fengxia shi Yucai Tang +2 位作者 Dedong Ma xiangyun shi Guangbiao Zhao 《Fluid Dynamics & Materials Processing》 EI 2023年第10期2481-2497,共17页
In order to analyze the response of a hydraulic turbine to a variation in the operating conditions,different laws of variation in time of the massflow rate have been considered.After validating the overall numerical fr... In order to analyze the response of a hydraulic turbine to a variation in the operating conditions,different laws of variation in time of the massflow rate have been considered.After validating the overall numerical framework through comparison with relevant experiments,the performances of the considered turbine have been analyzed from afluid-dynamic point of view.The results show that different time profiles of the massflow rate(in this work,for simplicity,referred to as“transition functions”)have a varying influence on the transient behavior of the turbine.When a quadratic function is considered for the case of largeflow,the transient head and torque increase gradually with time,thefluctuation amplitude of the transient hydraulic efficiency at the main frequency is the largest,and thefluctuation amplitude of the radial force is the smallest.For the smallflow case,the time profile with exponential nature leads to the best results.The transient head and torque decrease gradually with time,the pulsation amplitude of the transient hydraulic efficiency is the largest at the main frequency,and the pulsation amplitude of the radial force is the smallest. 展开更多
关键词 Transition functions hydraulic turbine transition process radial resultant force
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Dynamics of a stochastic periodic SIRS model with time delay
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作者 xiangyun shi Yimeng Cao 《International Journal of Biomathematics》 SCIE 2020年第8期25-42,共18页
Dynamical behaviors of a siocluustic periodic SIRS epidemic model with time delay are investigated.By constructing suitable Lyapunov functions and applying Ito's formula,the existence of the global positive soluti... Dynamical behaviors of a siocluustic periodic SIRS epidemic model with time delay are investigated.By constructing suitable Lyapunov functions and applying Ito's formula,the existence of the global positive solution and the property of stochastically ultimate boundedness of model(1.1)are proved.Moreover,the extinction and the persistence of the disease are established.The results are verified by numerical simulations. 展开更多
关键词 Stochastic periodic model DELAY EXTINCTION stochcistically ultimate boundedness PERSISTENCE
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