Seminar Series
SPRING 98


Date

Mar 27,1998

Time

10:00 am

Location

102D , Cullen College of Engineering

Topic

Generalized Enhanced Exchange Hueristic based resource constrained scheduler compared with evolutionary scheduling

Speaker

Mr.Inkap Song

    Mr Inkap Song

Abstract

The Exchange Heuristic (EH) is a tool that solves Resource Constrained Scheduling (RCS) problems with general assumptions. EH attempts to balance resource utilization throughout the scheduling period. EH does this by shifting some activities later in the schedule to make enough space to assign a promising activity earlier in the schedule. This reassignment frequently leads to an improvement in the schedule by maximizing resource utilization. The promising activity is termed "target activity". Selecting the most promising target, as well as the order of activities to be shifted, constitutes the success of EH. The EH as it is currently practiced is highly dependent on an expert's intuition in these operations. This research suggests improving current EH practices by human experts with the use of neural networks (NN), due to their outstanding capability to both learn and deal with fuzzy data. Different measures of attributes are considered to express the configuration of a schedule. Training neural networks requires a set of examples, and each example consists of a calculation of the attribute values. From the trained NN, synaptic weights are obtained, and these weights are used for the NN implemented in mathematically in this study. Generalized Enhanced Exchange Heuristic (GEEH). Also, EH is formally described In GEEH, fixed resource capacity and requirements for each activity are relaxed. In addition, expendable resources are introduced. Expendable resources, like money, are an important consideration in practical applications. Therefore, the cost evaluation of the different scenarios in a project becomes possible. Furthermore, GEEH generalizes the concept of the predecessor by including weak predecessors. As an extension of the study, the comparison study of EH with Evolutionary Scheduling (ES) is conducted. The ES is introduced, and the semi-global nature of the EH is discussed. A Hybrid method of ES and EH is suggested, and compared with EH and ES.


Note

All Are Welcome.  Refreshments will be served.