Page 201 - DCOM303_DMGT504_OPERATION_RESEARCH

Operations Research Dilfraz Singh, Lovely Professional University

Notes Unit 10: Sequencing Problems and Replacement Theory

CONTENTS
Objectives
Introduction
10.1 Terminology

10.2 Types of Sequencing Problems
10.3 Algorithm for Sequencing Problems
10.3.1 Type I: Processing n Jobs through Two Machines
10.3.2 Type II: Processing n Jobs through Three Machines
10.4 Replacement Theory

10.4.1 Need for Replacement
10.5 Consideration of Money Value for Investments on Machines or Equipments.
10.5.1 Replacement Policy Decisions
10.6 Summary
10.7 Keywords
10.8 Review Questions

10.9 Further Readings

Objectives

After studying this unit, you will be able to:
 Appreciate the aims to study sequencing problems

 Use Johnson’s rule of sequencing
 Solve some specific problems of scheduling jobs on one machine, two and three machines
 Learn about the application of replacement theory.

Introduction

Sequencing deals with the selection of an optimum order for the number of jobs to be performed
with a finite number of facilities. The objective of sequencing is to determine the sequence of
performing jobs such that the total cost/time is minimized.

Sequencing problems arise in situation like a manufacturing plant for performing orders, in a
hospital where the patients wait for different type of tests and in a bank where customers wait
for different types of transactions, etc.

10.1 Terminology

 Processing Time t : It is the time required by a job i on each machine j.
ij

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