专业英语第六章.ppt

In economic evaluations, project alternatives are represented by their cash flow profiles over the n years or periods in the planning horizon. 在经济评价中，每一个备选项目都用它在以后N年或者规划周期内的现金流量分布形态一一表示Thus, the interest periods are normally assumed to be in years t = 0,1,2, .,n with t = 0 representing the present time.这样，计息周期一般用年来表示（t=0,1,2，···，n），t=0时表示当前时刻Let Bt,x be the annual benefit at the end of year t for an investment project x where x = 1, 2, . refer to projects No. 1, No. 2, etc., respectively.我们用Bt,x来表示一个投资项目x在t年末的年收益，x=1,2···表示备选项目的标号No.1,No.2······。

Let Ct,x be the annual cost at the end of year t for the same investment project x. 我们用Ct,x来表示同一个投资项目x在t年末年成本支出The net annual cash flow is defined as the annual benefit in excess of the annual cost, and is denoted by At,x at the end of year t for an investment project x. Then, for t = 0,1, . . . ,n:一个投资项目x在t年末的净现金流量就用年收益减去年成本费用得到，用At,x表示t=0,1···n时，公式为,,where At,x is positive, negative or zero depends on the values of Bt,x and Ct,x, both of which are defined as positive quantities. At,x 是正值、负值或者零值取决于 Bt,x 与Ct,x的值，其中Bt,x 与Ct,x均为正值,,Once the management has committed funds to a specific project, it must forego other investment opportunities which might have been undertaken by using the same funds. 管理者一旦将资金投入到某一特定的投资项目中，就必须放弃这笔资金投入到其他的项目的获利机会。

The opportunity cost reflects the return that can be earned from the best alternative investment opportunity foregone. 机会成本是在所放弃的的投资方案中可从最优的备选方案中获得的收益The foregone opportunities may include not only capital projects but also financial investments or other socially desirable programs. 被放弃的投资项目不仅包括资本项目还包括金融投资或者社会公益项目投资Management should invest in a proposed project only if it will yield a return at least equal to the minimum attractive rate of return (MARR) from foregone opportunities as envisioned by the organization.只有当一个投资项目能产出的回报至少等于最低收益率时,决策者才会投资该拟建项目（最低收益时的回报即组织设想的所放弃的投资项目的回报）.,。