Refer to “Activity-on-node networks with minimal and maximal time lags and their application to make-to-order production”. (Neumann & Schwindt, 1997)
At first, we review some basic concepts from material requirements planning (ref Nahmias, 1997, Ch. 6, or Neumann, 1996, Ch. 4). A final product or end item is the output of the underlying productive system, that is, a product which is shipped out the door. Components or intermediate products are items that are in intermediate stages of production. Raw materials, which enter the system, are also viewed as components. The external demand for a product is called its primary requirement. Note that there may also be a primary requirement for some components that do not represent end items (for example, spare parts). The secondary requirement for a component A is the amount of item a required to produce all items at higher production levels. The sum of the primary and secondary requirement for a product is called its gross requirement. (Ahern 2000, 385)
Timing of Activities in Gantt Chart format (from MS Project)
The predecessor and successor relationship and the duration of each activity are known in this case. Earliest start time equals to the earliest finish time of predecessor activity. Earliest finish time equals to the earliest start time plus to the activity duration. Latest finish time equals to the latest start time of successor activity and Latest start time equals to the latest finish time minors the duration. The total float means the difference between earliest start time and the latest start time. (Arnone 1992, 15)
To time or record a single activity, record the activity date into the date box. Use the Name box to identify the person performing the service. In the Customer: Job box, identify the customer or the job for which the service is being performed. Select the appropriate service item from the Service Item drop-down list box. If you're tracking classes, predictably, you can also use the Class drop-down list box to classify the activity. The Notes box should be used to record a brief appropriate description of the service. This description appears on the invoice so be thoughtful about what you write. After describing or providing this general information about the service, you have two ways to record the time spent on the service. (Baylor 2002, 395)
After all the activities are done, the life circle of project is finished. And that time is the total duration of the project itself. Critical Path Method (CPM) is a kind of model to calculate the critical path in the whole project, which will have the biggest influence to the project total duration. In this case, the Total project duration is 83 days, as the activity Q is finished in that day. The critical path is the process of A-E-F-G-H-I-K-L-M-N-P-Q. If any change occurs in those activities, then the total duration will be change definitely. The use of CPM enables the most economical planning ...