文档介绍：Chapter 6 Scheduling
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Learning Objectives
估计每项活动的工期
确定整个项目的预计开始时间和要求完工时间
在项目预计开始时间的基础上计算每项活动必须开始和完成的最早时间
利用项目的要求完工时间计算每项活动必须开始和完成的最迟时间
确定每项活动的时差
确定关键活动路径
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Real World Example
te: R. R. Donnelley & Sons (page 84)
Project: 使18000多个使用许多种不同的电子邮件系统的用户,转而使用一个标准的系统,并且这些用户是散布在亚、欧、南北美的200多家工厂之中。
The project pleted six months ahead of schedule without any disruption to business processing.
Lessons Learned: detailed planning and scheduling are essential; resource management is crucial; and you must have great teamwork.
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Real World Example
te: London Ambulance Service (page 101)
Project: After two failed attempts, develop an ambulance dispatching system capable of handling a million calls per year based on 800 vehicles, million residents, million tourists, dispersed over 640 square miles.
Results: the number of ambulances on the way within three minutes doubled; the number of ambulances on the scene within 8 minutes tripled. Lives are being saved.
Lessons Learned: encourage munications; involve the team in planning; break the project into manageable pieces.
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Activity Duration Estimates
The first step in scheduling is to estimate how long each activity will take.
每项活动的工期估计(duration estimate):该活动经历的所有时间,即工作时间加上所有相关的等待时间
经验表明,让某项活动的负责人进行该项活动的工期估计是较好的做法。
对某项活动的工期进行估计时,必须以这项活动所使用的资源数量为基础。
在项目执行过程中,一些活动花费的时间可能比预计工期要长,一些则可能要短,还有一些可能正好与工期估计吻合。然而,每个项目的生命周期都包括许多活动,因此这些延误和提前可以相互抵消。
对于一个项目,如果含有高度不确定性工期估计的活动,可以用三种工期估计:乐观、悲观和最可能时间估计(PERT方法)。
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Project Start and Finish Times
It is necessary to select an estimated start time and a pletion time for the overall project.
这两个时间(或日期)规定了项目必须完成所需的时间段,即给出了项目必须完成的时间限制。
项目的要求完工时间通常是项目目标的一部分,要在合同中明确。一般情况下,预计开始时间和要求完工时间都要在合同中明确。
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Schedule Calculations
A project schedule includes:
the earliest times (or dates) at which each activity can start and finish, based on the project's estimated start time (or date)
the latest times (or dates) by which each activity must start and finish in order plete the project by its pletion