South African Journal of Industrial Engineering

This study was motivated by the high costs incurred by an energy company for repairable spare parts for faulty mission-critical items, particularly with those that operate until failure. The objective of this paper is to develop and apply a method for repairable spare part inventory management of run-to-failure equipment. To achieve a robust method that incorporates the data collected from previous failures, such as environmental factors and operating conditions, we propose an optimisation approach based on an accelerated failure time model. Accelerated failure time is used as a reliability regression model with covariates to describe different operational conditions. An algorithm is also developed to consider the repairable nature of the equipment, predicting the number of spare parts based on the expected number of failures in the period and the equipment repair cycle. The proposed method is applied using data from three different power units of electrical submersible pumps, a mission-critical item in oil production. The results show an average reduction of 60.6 per cent in the required number of spare parts, considering an average fill rate of 95.33 per cent. This reduction implies an estimated annual savings of around US$664,720 in inventory costs, considering the analysed units.

Die hoë kostes wat energiemaatskappye op die hals haal vir spaar onderdele vir kritiese items dien as motivering vir hierdie studie. Die doel is om ʼn metode wat die inventarisbestuur van herstelbare spaar onderdele te ontwikkel en toe te pas vir bedryf-tot-faling toerusting. Om ʼn robuuste metode wat vorige falingsdata inkorporeer te ontwikkel word ʼn optimisering benadering wat op ʼn versnelde falingstyd model gebaseer is gebruik. Versnelde falingstyd word gebruik as ʼn betroubaarheid regressie model met kovariate om die verskillende operasionele toestande te beskryf. ʼn Algoritme is ook ontwikkel om die herstelbaarheid van die toerusting in ag te neem en dit voorspel die aantal spaar onderdele op grond van die verwagte aantal falings in die periode en die toerusting herstelsiklus. Die voorgetelde metode is toegepas op data van drie verskillende aandrywingseenhede van elektriese dompelpompe. Die resultate toon dat ʼn gemiddelde vermindering van 60.6 persent in die aantal spaar onderdele wanneer ʼn gemiddelde vulsyfer van 95.33 persent oorweeg is. Die vermindering bewerkstellig ʼn jaarlikse besparing van ongeveer US$664,720 in inventaris onkostes vir die oorweegde pompeenhede.

Revolutionary advances in the information and communication technology field pave the way for automation and data exchange in the heavy industry sector. Currently, Industry 4.0 solutions are more readily accepted in factories and in more advanced economies, where good infrastructure is in place to facilitate these solutions. In the context of these heavy industries, wide-area wireless telemetry networks play an important role in facilitating accessibility and allowing for real-time monitoring and data transmission over wide geographical distances. This paper emphasises the value of a new wireless telemetry monitoring and diagnostic system that allows for the development of a detailed troubleshooting methodology when communication disruptions occur. The system was implemented on an existing telemetry system that is used by an energy services company to maintain the operational status of various remote information systems. The network is also used to facilitate various demand-side management projects throughout the Republic of South Africa. The results obtained show that the proposed system can enhance the robustness of existing Industrial Internet of Things infrastructure, and this promotes the adoption of Industry 4.0 concepts in the heavy industry sector.

Revolusionêre vooruitgang in die inligting- en kommunikasietegnologie-veld baan die weg vir outomatisering en data-uitruil in die swaar nywerheidsektor. Tans word oplossings van Industrie 4.0 makliker in fabrieke en in meer gevorderde ekonomieë aanvaar waar goeie infrastruktuur in plek is om hierdie oplossings te fasiliteer. In die konteks van hierdie swaar nywerhede speel wye draadlose telemetrie netwerke ’n belangrike rol om toeganklikheid te vergemaklik en vir intydse monitering en data-oordrag oor wye geografiese afstande voorsiening te maak. Hierdie manuskrip beklemtoon die waarde van ’n nuwe draadlose telemetrie monitering en diagnostiese stelsel om toe te laat dat ’n gedetailleerde probleemoplossingsmetodologie ontwikkel word wanneer kommunikasie-versteurings plaasvind. Die stelsel is geïmplementeer op ’n bestaande telemetrie stelsel wat gebruik word om die operasionele status van verskeie afgeleë inligtingstelsels te handhaaf. Die resultate het getoon dat die voorgestelde stelsel die robuustheid van bestaande ‘Industrial Internet of Things′-infrastruktuur kan verbeter, en dit bevorder die aanvaarding van Industrie 4.0 konsepte in die swaar nywerheidsektor.

Trying to find a parking space in a parking lot is a routine activity for most people in our society. However, in managing the sustained growth rate in the number of vehicle users, the demand on such parking facilities is likely to remain under constant pressure. Both the users and the management of parking lots use various strategies in dealing with the requirement for suitable parking facilities. This paper presents a computational model using an agent-based modelling technique to simulate two commonly used strategies applied to choosing a parking spot under various demand and supply conditions. The model is unique in the current literature, as it is specifically designed to evaluate the effectiveness of the strategies. The analysis of the experimental results shows that, in most conditions, accepting the first available parking spot and then walking to the destination performed better than driving as close as possible to the destination and then searching for an available parking spot.

Om ʼn parkeerplek op te spoor is ʼn roetine aktiwiteit vir die meeste mense in ons samelewing. Die bestuur van die volgehoue groeikoers in die aantal voertuiggebruikers plaas egter die vraag na parkeerfasiliteite onder volgehoue druk. Beide die gebruikers en die bestuur van parkeerterreine gebruik verskeie strategieë om die behoefte aan gepaste parkeerfasiliteite te hanteer. Hierdie artikel bied ʼn berekeningsmodel aan met ʼn agentgebaseerde modelleringstegniek om twee algemene parkeerplek-soek strategieë te simuleer onderhewig aan verskillende vraag en aanbod toestande. Die model is uniek in die beskikbare literatuur omdat dit spesifiek ontwikkel is om die doeltreffendheid van die strategieë te beoordeel. Ontleding van die eksperimentele resultate toon dat, in die meeste gevalle, die aanvaarding van die eerste beskikbare parkeerplek en dan te loop tot by die eindbestemming beter resultate lewer as om tot by die bestemming te ry en dan vir ʼn beskikbare parkeerplek te begin soek.