Solidification structure is critical in the control of the mechanical properties and quality during the continuous casting process. The thermo-physical properties of 13 Cr steel added some rare metals, such as Mo, V, ...Solidification structure is critical in the control of the mechanical properties and quality during the continuous casting process. The thermo-physical properties of 13 Cr steel added some rare metals, such as Mo, V, Nb, are measured to better understand the solidification structure of 13 Cr bloom. A computational model using CA-FE(cellular automation-finite element) method coupled with heat transfer model is developed to describe the solidification structure in continuous casting process. It is found that the calculated solidification structure is in good agreement with the observed data. The influence of casting speed and superheat on the solidification structure of the bloom is studied in detail. In order to obtain more equiaxed crystal ratio and low degree of the segregation in the bloom, the optimized casting speed 0.6 m/min and superheat less than 25 °C are determined for the caster. Using the optimized manufacturing parameters, these samples are 60% with the equiaxed zone ratio of 8%–10% and below the degree of segregation 1.05.展开更多
In this paper,two new models suitable for power system stability analysis with considering time delays are derived.They are constraint time-delayed ordinary differential equation model(CTODE model) and constraint time...In this paper,two new models suitable for power system stability analysis with considering time delays are derived.They are constraint time-delayed ordinary differential equation model(CTODE model) and constraint time-delayed differential algebraic equation model(CTDAE model).In these two models,dimension of the time-delayed equation is significantly reduced so as to speed up the calculation efficiency.Detail derivations to their nonlinear and incremental linear forms are given.And,some of their good features are discussed.Finally,a typical time-delayed system and single-machine-infinite-bus system are selected to validate the new models through Lyapunov-Krasovskii criterion and eigenvalue locus tracing procedure.It reveals that some unnecessary calculations in the algorithm can be avoided to achieve higher efficiency based on new models.The new models and new criterion given in this paper are helpful to design wide area protectors for bulk power systems.展开更多
基金Projects(51274057,51474057) supported by the National Natural Science Foundation of ChinaProject(2012AA03A508) supported by the High-tech Research and Development Program of China
文摘Solidification structure is critical in the control of the mechanical properties and quality during the continuous casting process. The thermo-physical properties of 13 Cr steel added some rare metals, such as Mo, V, Nb, are measured to better understand the solidification structure of 13 Cr bloom. A computational model using CA-FE(cellular automation-finite element) method coupled with heat transfer model is developed to describe the solidification structure in continuous casting process. It is found that the calculated solidification structure is in good agreement with the observed data. The influence of casting speed and superheat on the solidification structure of the bloom is studied in detail. In order to obtain more equiaxed crystal ratio and low degree of the segregation in the bloom, the optimized casting speed 0.6 m/min and superheat less than 25 °C are determined for the caster. Using the optimized manufacturing parameters, these samples are 60% with the equiaxed zone ratio of 8%–10% and below the degree of segregation 1.05.
基金supported by Special Fund of the National Basic Research Program of China("973"Program)(Grant No.2009CB219701)National Natural Science Foundation of China(Grant No.51277128)State Grid Corporation of China(Grant No.SGCC-MPLG028-2012)
文摘In this paper,two new models suitable for power system stability analysis with considering time delays are derived.They are constraint time-delayed ordinary differential equation model(CTODE model) and constraint time-delayed differential algebraic equation model(CTDAE model).In these two models,dimension of the time-delayed equation is significantly reduced so as to speed up the calculation efficiency.Detail derivations to their nonlinear and incremental linear forms are given.And,some of their good features are discussed.Finally,a typical time-delayed system and single-machine-infinite-bus system are selected to validate the new models through Lyapunov-Krasovskii criterion and eigenvalue locus tracing procedure.It reveals that some unnecessary calculations in the algorithm can be avoided to achieve higher efficiency based on new models.The new models and new criterion given in this paper are helpful to design wide area protectors for bulk power systems.
