采用关联模型比较典型的案例是“尿布与啤酒” 的故事。在美国,一些年轻的父亲下班后经常 要到超市去买婴儿尿布,超市也因此发现了 个规律,在购买婴儿尿布的年轻父亲们中,有 30%~40%的人同时要买一些啤酒。超市随后 调整了货架的摆放,把尿布和啤酒放在一起, 明显增加了销售额。同样的,我们还可以根据 关联规则在商品销售方面做各种促销活动

2004年中国旅游业全面振兴和蓬勃发展。全年入境 人数突破1亿人次大关,入境过夜旅游者突破4000 万人次,旅游外汇收入突破250亿美元,旅游总收 入超过6800亿人民币。2004年,经国务院批准新开 放的旅游目的地达38个国家,这样,中国公民出国 旅游目的地国家和地区共计达到了92个,已经开展 公民组团旅游业务的达63个

一、桥梁建设成就 我国桥梁建设历史源远流长,早在公元1300多年前建造的赵州桥, 结构新颖、坚固美观。800多年前修建的卢沟桥,古朴典雅、雄伟壮丽, 今仍被誉为世界桥梁建筑史上的杰作。古代的石梁桥,悬臂木梁桥及铁 索桥的建设成就,也达到了较高的技术水平,在国际桥梁史上占有非常 重要的地位

1叶格尔CM等著.飞机设计.杨景佐等译.北京:航空工业出版社,1986 2杨景佐,曹名编.飞机总体设计.北京:航空工业出版社,1991 3 Raymer D P. Aircraft Design: A Conceptal Approach. AlAA Education Series, 1992 4[美]雷曼尔DP著.现代飞机设计.钟定逵等译.北京:国防工业出版社,1992

The work of the external forces in the spring system of the figure is given by W=B*(U1+U2+U3)(2) W=P1*U1+P2米U2+B米U3(3) None of the above statements

The state of stress at a point is completely determined when: 1. the stress vectors on three different planes are specified 2. the stress vectors on two different planes are speciale 3. the stress vectors one arbitrary plane is spec-

not repeated in the same additive term where the index appears. Free means that the index represents all the values in its range Latin indices will range from 1 to, (i,j, k

For the potato-shaped body given in class to explain the concept of stress, the field of stress vectors t(n)=t(n)(x)on the plane of normal n given by its cartesian components(1,0, 0) known and its cartesian components are given by the expression

Concept Question Consider the following simple displacement field

16.21 Techniques of Structural Analysis and sig Spring 2003 Unit #4- Thermodynamics Principles First Law of Thermodynamics