An effective method was proposed to establish the continuous cooling transformation（CCT） diagrams of aluminum alloys using in situ voltage measurement.The voltage change of samples with predefined dimension was reco...An effective method was proposed to establish the continuous cooling transformation（CCT） diagrams of aluminum alloys using in situ voltage measurement.The voltage change of samples with predefined dimension was recorded under the constant current state during continuous cooling.Solutionizing time,together with starting and finishing temperatures of phase transformation of the alloy can be obtained from relationships of voltage vs time and temperature.A critical cooling rate without detectable phase transition during continuous cooling can be determined.Continuous cooling transformation diagrams of tested samples can be established conveniently based on these results.Microstructure observation and differential scanning calorimetry（DSC） testing were applied to verify the reliability of continuous cooling transformation diagram.展开更多
This paper considers the problem of estimating the bounds on the average controlled direct effects （ACDEs） of a treatment variable on an unobserved response variable in the presence of unobserved confounders between...This paper considers the problem of estimating the bounds on the average controlled direct effects （ACDEs） of a treatment variable on an unobserved response variable in the presence of unobserved confounders between an intermediate variable and the response variable. When the response variable is observed, Cai, et al.（2008） derived the formulas for the sharp bounds on the ACDEs. When the response variable is unobserved, the authors propose a graphical criterion for selecting variables affected by the response variable to derive the formulas for the bounds on the ACDEs, which is an extension of the result of Kuroki（2005） to ACDEs. The results enable us not only to judge from the graph structure whether the bounds on the ACDEs can be expressed through observed variables when the response variable is unobserved, but also to provide their formulas when the answer is affirmative.展开更多
文摘An effective method was proposed to establish the continuous cooling transformation（CCT） diagrams of aluminum alloys using in situ voltage measurement.The voltage change of samples with predefined dimension was recorded under the constant current state during continuous cooling.Solutionizing time,together with starting and finishing temperatures of phase transformation of the alloy can be obtained from relationships of voltage vs time and temperature.A critical cooling rate without detectable phase transition during continuous cooling can be determined.Continuous cooling transformation diagrams of tested samples can be established conveniently based on these results.Microstructure observation and differential scanning calorimetry（DSC） testing were applied to verify the reliability of continuous cooling transformation diagram.
基金This research was partially supported by the National Natural Science Foundation of China under Grant Nos. 10871038, 10926186, and 11025102, the National 973 Key Project of China under Grant No. 2007CB311002, and the Jilin Project （20100401）.
文摘This paper considers the problem of estimating the bounds on the average controlled direct effects （ACDEs） of a treatment variable on an unobserved response variable in the presence of unobserved confounders between an intermediate variable and the response variable. When the response variable is observed, Cai, et al.（2008） derived the formulas for the sharp bounds on the ACDEs. When the response variable is unobserved, the authors propose a graphical criterion for selecting variables affected by the response variable to derive the formulas for the bounds on the ACDEs, which is an extension of the result of Kuroki（2005） to ACDEs. The results enable us not only to judge from the graph structure whether the bounds on the ACDEs can be expressed through observed variables when the response variable is unobserved, but also to provide their formulas when the answer is affirmative.
