·480· 北京科技大半学报 2006年第5期 Monte-Carlo direct simulation of paramagnetic and diamagnetic mixed gas flows in gradient magnetic fields CAI Jun1),WANG Li,WU Ping2,SHANG Xiaohang3) 1)Mechanical Engineering School,University of Science and Technology Beijing,Beijing 100083.China 2)Applied Science School,University of Science and Technology Beijing,Beijing 100083,China 3)School of Information Engineering.Beijing Union University.Beijing 100080,China ABSTRACT With a mixture of oxygen and nitrogen as the subject investigated,the direct simulation Monte-Carlo method was applied to simulate the flow of paramagnetic and diamagnetic mixed gas in high gradient magnetic fields.The simulated results were compared with the existing experimental ones,and the reliability of the program was demonstrated.It was shown that the increment of oxygen concentration in- creased from 0.12%to 1.89%when the product of magnetic field and gradient varied from 100T2.mto 1000T2.m.The increment of oxygen concentration reduced from 0.4%to 0.1%when the temperature varied from 273K to 333K.The increment rose from 0.12%to 0.59%when the initial oxygen concentra- tion varied from 20%to 30%.The change in pressure did not almost influence the oxygen concentration. KEY WORDS gradient magnetic field;direct simulation Monte-Carlo method;paramagnetism;simula- tion (上接第470页) Effect of SmartCrown work roll wear contour pattern on controllability of profile and flatness in tandem cold rolling mills JIA Shenghui,CAO Jianguo,ZHANG Jie,YIN Xiaoqing?,LU Haitao,YANG Guanghui 1)Mechanical Engineering School,University of Science and Technology Beijing.Beijing 100083,China 2)Wuhan Iron Steel (Group)Company,Wuhan 430083,China ABSTRACT In order to master the SmartCrown system for profile and flatness control first applied on a 1700mm tandem cold rolling mill,the SmartCrown work roll wear pattern was obtained on the basis of large amount of measured roll contours.A prediction wear model of the SmartCrown work rolls was built up by using genetic algorithm.The effect of the roll wear contour pattern on profile and flatness performance was analyzed by the developed three-dimensional finite element analysis model of a roll stacks system with ANSYS software.A new rolling strategy was brought forward for application of the new SmartCrown sys- tem. KEY WORDS tandem cold rolling mill;profile and flatness control;roll;wear;mathematical model· 4 0 8 · 北 京 科 技 大 学 学 报 2 0 0 ` 年第 5 期 M o n t e 一 C a r l o d i r e e t s im u l a t i o n o f a r a m a g n e t i e a n d d i a m a g n e t i e m i x e d g a s f o l P w s i n g r a d i e n t m a g n e t i e fi e d l s 以了J u n l ) , w A N G 乙1 1 ) , w u 几 n g Z ) , S H摊 N G x ia 诚a n g 3 ) l ) M ec h an i e a l E n g i n e r i n g cS h co l , U n i v e rs i t y o f cS i e n e e a n d T ce h on 吨y Be ij i n g , eB ij i呢 1 0 0 0 8 3 , C h i n a 2 ) A pp lide 反i e n e e cS h o l , U n i v e rs i t y o f cS i e n e e a n d T ce h n o l o g y Be ij i呢 , Be ij i昭 10 0 0 8 3 . 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