The key to prediction of casting shrinkage / porosity lies in ascertaining the critical value of temperature gradient and niyama criterion . the thesis put forward two methods to ascertain the value , one is which is positive - direction and the other is negative - direction . we verify the realistic arithmetic of temperature gradient method and niyama criterion method by experiment , and we can draw a conclusion that the arithmetic is correct and reasonable in most cases and choice of developing tool is sound 临界梯度值和新山判据临界值的确定是实现缩孔缩松预测的关键，本文提出了确定临界值的正向法和反向法，并以高铬铸铁件缩孔缩松预测和铸造工艺改进为研究对象，应用正向法，确定了温度梯度法的临界值为180 m 。
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Patanjali gives eight stages of yoga viz . , yama ( universal moral commandments ) , niyama ( self - purification through discipline ) , asana ( posture ) , pranayama ( breath - control ) , pratyahara ( withdrawal of mind from external objects ) , dharana ( concentration ) , dhyana ( meditation ) and samadhi ( state of super - consciousness ) 帕坦伽利把瑜伽分成八步：控制欲念（普遍道德上的戒律） 、自我约束（通过纪律来自我净化） 、体式（身体姿势） 、调息（控制呼吸） 、感官抑制（把思想从外在物体中撤离） 、执持（思想集中） 、禅那（静坐冥想）和三摩地（超意识的状态） 。
