效用是消费者对产品满足其需要的整体能 力的评价。 Value is the consumer's estimate of the product's overall capacity to satisfy his or her needs. 消费者通常根据这种对产品价值的主观 评价和要支付的费用来作出购买决定

1. There have no two-phases area in diffusion area, every layer is single-phases 2. Phase's interface moves according to parabola law 3. Phase's width

The following stress-strain curves were obtained for dif- ferent materials subjecting the specimen to the loading path(a, b, c, d ). Which one(s) of them correspond to elas- tic material(s)

Chapter 5 Electronic commerce information's search and selection In physical markets, consumer search activities include reading advertisements, calling endors, and visiting stores. In a virtual marketplace, all these activities seem to converge into Web searches and Web browsing. Not surprisingly, search services are the first market infrastructure to be built in the electronic marketplace

一、设连续系统函数H(s)在虚轴上收敛,其幅频响应函数为H(j),试证幅度平方函数 H()?=H()(-s) sjo 二、其离散系统的系统函数z2+3z+2H(z)=2z-(K-1)z+1

2 concepts that enhance our understanding of risk... 1) Operating Leverage affects a firm's business risk. 2) Financial Leverage affects a firm's financial risk

通过考虑s平面内的D型围线,可以获得一种重要的并且很有用 的控制系统的设计方法。D型围线如下所示: 注意到该曲线的垂直部分穿越了整个虚轴,这也正是我们所知的 G(s)平面上的系统的频率响应

1解:△S=KhW=Kn (N-n)l n! F=△E-T△S=△E- KTLn N-ln(N-n)-lnn!] 根据 Stirling公式:当N很大时,hN=NhN-N,将上式整理得 △F=△E- KTINIn N-(N-n)h(N-n)-nhn] 平衡时,自由能具有最小值,由于热缺陷n引起的自由焓的变化()xp=0

1. Asymmetric auctions Consider an interdependent-values auction with two bidders, each of whom observes an i.i.d uniform signal s; E [ 0, 1]. Bidder i' s valuation for the object is equal to

从物理学知道,如果物体在做直线运动的过程中受到常力F作用,并且力F的 方向与物体运动的方向 致,那么,当物体移动了距离s时,力F对物体所作的功是W=F·s如果 物体在运动过程中所受到的力 是变化的,那么就遇到变力对物体作功的问题,下面通过例1说明如何计算变力 所作的功