Browsing by Author "Dewa, M. T."

Now showing 1 - 4 of 4
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    Agent based job scheduling for a vehicle engine reconditioning machine shop
    (Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Nyanga, L.; Van der Merwe, A. F.; Burawa, M.; Matope, S.; Dewa, M. T.
    ENGLISH ABSTRACT: Job scheduling at a machine shop is a multi-decision criteria problem whose skills are acquired after some years of experience. For Small, Medium to Micro Enterprises (SMMEs) with limited machinery the objective when scheduling jobs should not only focus on machine utilization but also on the increase of job through put. The paper presents an agent based job scheduling system for a vehicle engine reconditioning machine shop to assist decision makers in job scheduling. The Analytic Hierarchy Process (AHP) method was used to compute the relative weights of each decision criteria used for job scheduling considering the job priority. The value of the job, the number of operations to be performed, the engine type, the frequency of the customer and the company to customer relationship rating are used to prioritize the jobs. A Multi Agent System (MAS) comprising of the provider, job allocator and machine agents is developed using the Java Agent development framework (JADE) methodology and modelled using Unified Modelling Language (UML 2). The provider agent schedules all the jobs based on job weight and earliest due dates. The job allocator agent is responsible for making sure that all the scheduled jobs are allocated to all the machines after which they are registered as complete jobs and can leave the system.
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    Design of a multi agent system for machine selection
    (Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Nyanga, L.; Van der Merwe, A. F.; Tsakira, C.; Matope, S.; Dewa, M. T.
    ENGLISH ABSTRACT: In a machine shop effective assignment of jobs to machines is a multi-criteria decision making problem which is usually done by professionals and experienced planners. The skill of job assignment becomes handy in machine shops which are in the Small, Medium to Micro Enterprises (SMMEs) category as they work on a variety of products with limited machinery. The paper presents a machine selection system for helping decision makers when selecting machines to be scheduled. Customer order parameters which include product weight, clamping force, mould dimensions, due date and lead time are used to select moulding machines suitable to manufacture the desired parts. The criteria for machine selection was developed using Analytical Hierarchy Process (AHP) were quality, time and cost were considered as the key parameters. The available machines which meet the requirements for moulding a desired part are then made to compete for the part using an English auction. A Multi Agent System consisting of a managing agent, administrator and bidding agents was developed to conduct the auction that takes place between machine agents viewed as potential contractors representing available machines in the production line. The multi agent system is developed using Java Agent Development framework (JADE). An injection moulding plant with 11 injection moulders was used as a case study for application of the system.
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    A holonic approach to reactive scheduling when rush orders emerge
    (Faculty of Engineering, Department of Industrial Engineering, Stellenbosch University, 2016) Dewa, M. T.; Van der Merwe, A. F.; Matope, S.
    ENGLISH ABSTRACT: Rush orders can complicate the life of project managers when they emerge especially if they are of a high priority. Initially prepared process plans and schedules become invalid while extra capacity may be needed to meet the new demands placed on the shop-floor. However, with the era of distributed manufacturing, skills and resources can be shared in an optimal manner. The paper presents an application for automated management of resources in response to varying demands experienced by an industrial cluster of tool and dies workshops. A set of holons are utilized to monitor progress of orders in process while responding in real time to new demands placed on the system. The system utilizes the Petri-net protocol for the bidding function and automatically organizes the manufacturing function in a cost effective and timely manner. The ARENA discrete event simulation platform was utilized to demonstrate system’s results in a virtual environment.
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    Holonic control system : a proposed solution for managing dynamic events in a distributed manufacturing environment
    (South African Institute for Industrial Engineering, 2014) Dewa, M. T.; Matope, S.; Van der Merwe, A. F.; Nyanga, L.
    ENGLISH ABSTRACT: Due to globalization, manufacturing of products is no longer a local activity done by a single company but rather a distributed venture as more firms are realizing the need to improve their flexibility and agility. The paradigm of e-manufacturing is gaining popularity among researchers and manufacturers who aim to improve their market share and shop floor visibility by belonging to larger collaborative networks. However, real-time events which lead to operational disturbances in a plant remain a challenge most manufacturers face since they result in deviation from initially prepared process plans and schedules, rendering them invalid before they can be launched on to the shop floor for implementation. The paper presents a Holonic Control System (HCS) as a proposed solution to managing this pandemic. The research focused on manufacturing firms in the Western Cape of South Africa which belong to the tooling industry. Cited in this paper are holonic architecture together with the success factors and barriers to implementing holonic control systems in South Africa. Results of the proposed system were generated by a simulation model and revealed that delivery time and resource utilization were improved by adopting the system.