。608· 北京科技大学学报 2006年第6期 A method for attributes reduction based on scan vector EXu2》,GA0 Xuedong”,YU Bin 1)Department of Computer Science.Liaoning Institute of Technology.Jinzhou 121001.China 2)Management School Uriversity of Science and Technology Beiing,Beijing 100083,China ABSTRACT In order to deal with attributes reduction,one of the major problems in rough set theory,an attributes reduction algorithm was proposed based on scan vector,and a new conception of discemible vec- tor w as defined by which the info mation table can be transformed into discernible vector sets.Depending on the structural feature of the discernible vector,a plus rule for the discernible vector sets was defined,and a scan vector with co ncise structure but representing the info rmation table can be obtained through scanning the discernible vector just one time.The item of attribute frequency in the scan vector was taken as heuris- tic information to improve the efficiency of attributes reduction.An illustration and ex perimental results in- dicate that the method proposed is much more effective. KEY WORDS rough set;information table;att ributes reduction;discernible attributes set;scan vector (上接第586页) Numerical simulation on heat transfer of impinging slot jet LIU Guayong,LI Mouwei,WANG Bangwen,ZHANG Shaojun,LI Shengyong,HUANG Yan Mechanical Engineerin School University of Science and Technology Beijing,Beijing 100083 China ABSTRACT Numerical simulation w ith the standard ke model w as performed to study single-phase con- vective heat transfer at the impinging zone of non-immersed slot jet.The factors considered were jet veloci- ty,spacing of nozzle-to-impinging plate (height),slot width,angle betw een jet direction and plate,tem- peratures of impinged plate and water (liquid)from the slot nozzle.The results show that jet velocity is the most remarkable factor influencing heat transfer at the impinging zone and other factors such as water temperature and slot width are also non-negligible.The angle between jet direction and impinging plate on- ly influences the distribution of local convective heat transfer coefficient. KEY WORDS slot;impinging jet;convective heat transfer;ke model;numerical simulationA method for attributes reduction based on scan vector E Xu 1 , 2), GAO X uedong 1), Y U Bin 1) 1)Department of C omput er S cience , Liaoning Institut e of Technology , Jinzhou 121001 , China 2)Management S chool, Uni versit y of Science and Technology Beijing , Beijing 100083 , China ABSTRACT In order to deal w ith attributes reduction , one of the majo r problems in rough set theo ry , an attributes reduction algorithm w as proposed based on scan vecto r, and a new conceptio n of discernible vec￾tor w as defined by w hich the info rmation table can be transformed into discernible vecto r sets .Depending on the structural feature of the discernible vector , a plus rule fo r the discernible vecto r sets was defined , and a scan vector with co ncise structure but representing the info rmation table can be obtained through scanning the discernible vector just one time .The item of attribute frequency in the scan vector was taken as heuris￾tic information to improve the efficiency of attributes reduction .An illustration and ex perimental results in￾dicate that the method proposed is much more effective . KEY WORDS rough set ;info rmation table ;attributes reduction ;discernible attributes set ;scan vector (上接第 586 页) Numerical simulation on heat transfer of impinging slot jet LIU Guoyong , LI Mouwei , WANG Bangwen , ZHANG Shaojun , LI Shengyong , HUANG Yan Mechanical Engineering School, University of Science and Technology Beijing , Beijing 100083 , China ABSTRACT Numerical simulation w ith the standard k-εmodel w as performed to study single-phase con￾vective heat transfer at the impinging zone of non-immersed slot jet .The factors considered w ere jet veloci￾ty , spacing of nozzle-to-impinging plate (height), slo t width , angle betw een jet direction and plate , tem￾peratures of impinged plate and w ater (liquid)from the slot nozzle.The results show that jet velocity is the most remarkable factor influencing heat transfer at the impinging zone , and other factors such as water temperature and slot width are also non-negligible .The ang le between jet direction and impinging plate on￾ly influences the distribution of local convective heat transfer coefficient . KEY WORDS slot ;impinging jet ;convective heat transfer ;k-εmodel ;numerical simulation · 608 · 北 京 科 技 大 学 学 报 2006 年第 6 期