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A lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process, time varying demand and return rates

Dissertation (MEng (Industrial Engineering))--University of Pretoria, 2021.

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Other Authors: Adetunji, Olufemi
Format: Thesis
Language:English
Published: University of Pretoria 2022
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access_status_str Open Access
author2 Adetunji, Olufemi
author_browse Adetunji, Olufemi
author_facet Adetunji, Olufemi
collection Thesis
dc_rights_str_mv © 2022 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.
description Dissertation (MEng (Industrial Engineering))--University of Pretoria, 2021.
format Thesis
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institution University of Pretoria (South Africa)
language English
last_indexed 2026-06-10T12:38:48.199Z
license_str Other — see source repository
provenance_str_mv Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository
publishDate 2022
publishDateRange 2022
publishDateSort 2022
publisher University of Pretoria
publisherStr University of Pretoria
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spelling oai:repository.up.ac.za:2263/83888 A lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process, time varying demand and return rates Adetunji, Olufemi vzanneri@gmail.com Van Zyl, Anneri Inventory Remanufacturing Return logistics Defective yield Lot sizing UCTD Dissertation (MEng (Industrial Engineering))--University of Pretoria, 2021. Natural resource scarcity has accelerated considerations of return logistics in manufacturing processes. Most supply chain designs now consider a closed-loop design where demand can be satisfied by both newly manufactured goods as well as remanufactured returns, allowing for maximum value creation over the entire life cycle of a product. This dissertation proposes two inventory systems, one a dynamic lot sizing model and the other a closed form solution. It is also assumed that some items fail during manufacturing and these items are treated as returns that can be remanufactured to satisfy one of two types of demand. Returns are remanufactured to one of two states such that items that may not be remanufactured to an as-good-as-new state of the first product can satisfy a secondary customer demand of a lower grade. Returns are constrained by expressing customer returns as a percentage of demand and items that fail during manufacturing as a percentage of the manufacturing batch. In the dynamic lot sizing model, the remanufacturing processes require some other components to be procured to bring the returned items back to either of the two states of reuse. A modified Wagner/Whitin model for the alternate application of remanufacturing and manufacturing for the satisfaction of the top range item demand and supplemented by a modified reverse Wagner/Whitin model for the remanufacturing of the lower variety items is derived to solve the dynamic lot sizing model proposed. The closed form solution considers that additional feedstock for the top range item can be procured in the case that the demand cannot be fully satisfied by the manufacturing and remanufacturing processes respectively. Both models aimed to minimize cost across a horizon and the total cost proves to be very sensitive to the manufacturing setup cost and the proportion of demand returned for remanufacturing in the case of the dynamic model and Type A serviceable holding cost and the Type A product yield rate from the manufacturing process in the case of the closed form solution. Industrial and Systems Engineering MEng (Industrial Engineering) Unrestricted 2022-02-14T11:31:53Z 2022-02-14T11:31:53Z 2022-04 2021 Dissertation * A2022 http://hdl.handle.net/2263/83888 en © 2022 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria
spellingShingle Inventory
Remanufacturing
Return logistics
Defective yield
Lot sizing
UCTD
A lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process, time varying demand and return rates
title A lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process, time varying demand and return rates
title_full A lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process, time varying demand and return rates
title_fullStr A lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process, time varying demand and return rates
title_full_unstemmed A lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process, time varying demand and return rates
title_short A lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process, time varying demand and return rates
title_sort lot sizing problem in reverse for two items of different quality grades with an imperfect manufacturing process time varying demand and return rates
topic Inventory
Remanufacturing
Return logistics
Defective yield
Lot sizing
UCTD
url http://hdl.handle.net/2263/83888