www.tjprc.org SCOPUS Indexed Journal editor@tjprc.org JOB SHOP SCHEDULING USING DIFFERENTIAL EVOLUTION ALGORITHM P. SHILPA 1 & G. BALARAJU 2 1 Assistant Professor, Department of Mechanical Engineering, ACE Engineering College, Ghatkesar, Hyderabad, Telangana, India 2 Professor, Department of Mechanical Engineering, ACE Engineering College, Ghatkesar Hyderabad, Telangana, India ABSTRACT This paper presents a differential evolution approach for job shop scheduling problems. The job shop scheduling problem, a class of combinatorial optimization problem that involves discrete optimization over discrete variables and the most important objective is makes to pan minimization. The differential evolution approach is a stochastic based effective adaptive scheme for global optimization over continuous space. In order to apply the differential evolution algorithm for the job shop scheduling problem, a suitable encoding mechanism is required to generate an operation schedule. In the present work, the operation schedule is generated using random keys encoding scheme that deals with floating point vectors and a local search heuristic is used to achieve the best optimal solution. The proposed approach is extensively tested on a set of standard job shop scheduling instances and the results are compared with the best- known solutions. It is observed that the proposed approach is performing well on all the test problems. KEYWORDS: Job Shop Scheduling, Differential Evolution, Random Keys, Makes Pan & Local Search Received: Mar 20, 2018; Accepted: Apr 10, 2018; Published: May 03, 2018; Paper Id.: IJMPERDJUN201837 INTRODUCTION Increasing changes in the technology and customers demand made an impact on manufacturing strategies and emphasized the need for products in small volume. To stay competitive in this dynamic environment that demands quick delivery of products at low cost, there is a need for effective scheduling of the production activities (Jain, 1999). Hence, most of the research is focused on the job shop scheduling that suits the present day customers demand. Then- job and m- machine job shop scheduling problem (JSSP) is one of the most general production problems. Each job consists, a set of operations and each operation of the job is characterized by a specific machine and its corresponding processing time. The Job characteristics typically impose certain constraints such as precedence relations among the operations of a job, job priorities and job due date’s etc., make the problem more complex in nature. The most important objective of scheduling problems is to minimize the total completion time of all the jobs and is referred as makes pan and the other objectives include minimization of mean flow time and mean tardiness (Baker,1974) Scheduling problems are combinatorial in nature and solving such problems amounts to make a discrete choice of an optimal solution among the finite number of alternatives available (Bagchi, 1999). Decisions involve which job to be scheduled first and when to schedule the next job. There are two types of order relations in the job shop scheduling problem. One is operation sequence on each machine and another is precedence constraints among Original Article International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN (P): 2249-6890; ISSN (E): 2249-8001 Vol. 8, Issue 3, Jun 2018, 327-338 © TJPRC Pvt. Ltd.