Leon Pretorius | University of Pretoria (original) (raw)

Papers by Leon Pretorius

Computers & Industrial Engineering, Jun 18, 2012

2018 IEEE Technology and Engineering Management Conference (TEMSCON), 2018

In a complex mining environment sub processes are interlinked and dependent on each other. At eac... more In a complex mining environment sub processes are interlinked and dependent on each other. At each step of mining the actions of one heavily impact on the next process. The objective of this paper is to review the current mining environment and demonstrate whether it is possible to simulate a big surface mine in order to determine the impact of new technology or change of processes. The paper will discuss the approach taken to simulate the current and the future conditions. For this study, an openpit mine has been selected where iron ore is the only commodity. The initial aim of the broader study was to justify the need for drill rig automation in big mines and determine the value creation by means of simulation techniques. This paper will present the conceptual model developed to justify the need for automation specifically in the drilling process. The tool selected to achieve the objective is a System Dynamics tool called VENSIM. The process of creating the model and the logic behind the system dynamics is discussed. The conceptual model is presented with important focus areas in such a modelling attempt. Each mining process can be represented with stock and flow diagrams. The connections between each level is used to define the behavior of the system. A system will respond with three types of behavior; reaction, response and action. While reaction is sufficient, response is necessary when reaction is not sufficient. When this fails too, a change is required which is called an action. All these responses have a goal towards state-maintaining, goal-seeking and purposeful systems. State-maintaining systems often react to changes to maintain the state. A goal-seeking system is the one responds differently to a sequence of events until it reaches its purpose. A purposeful system can produce results in the same as well as different environments [5].

The aim of all companies is to increase their profitability and it is no different for the railwa... more The aim of all companies is to increase their profitability and it is no different for the railway environment. Possible steps toward obtaining this goal includes reducing costs, increasing productivity and efficiency. One focus area within the railway technical environment that can facilitate in obtaining these goals is maintenance. Even though conventional strategies such as corrective and preventive maintenance have proven to be lifesaving in some cases, it does not always adhere to the cost saving and process efficiency drives by companies. A new strategy of predictive maintenance is being investigated which is based on forecasting of system degradation through a prognostic process by using condition monitoring data. The objective of this paper is to propose a prognostic model which will be used for predicting the most cost and time effective maintenance schedule for a railway wagon based on the condition of its bogies, wheels, bearings and brake blocks.

South African Journal of Industrial Engineering, 2018

Indian Journal of Science and Technology, 2018

South African Journal of Industrial Engineering, Dec 1, 2016

International Journal of Learning and Change, 2021

A call centre is of strategic importance to an organisation and therefore needs to be developed w... more A call centre is of strategic importance to an organisation and therefore needs to be developed with ergonomics in mind. Call centre managers’ need to be trained in the field of ergonomics, so that an ergonomic “changeover” takes place to improve the workplace. Call centre agents are the lifeblood of the call center, and efficient managers need to do everything in their power to maintain a competitive workforce. The creation of worker friendly environment boosts the morale of the workforce, thereby reducing turnover and attracting professional agents. The issue of labour efficiency and productivity need to be addressed with the application of ergonomic principles which contribute process improvement. The result would be a reduction in absenteeism and worker's compensation claims as it is approximately ten million per year (www.statsa.org.za). Musculoskeletal disorders (MSDs) such as carpel tunnel syndrome arise from poor ergonomic practices. Thus, the focus of this article is to...

The SA clothing industry shed over 67 000 jobs in the past three years (Bell, 2006).There is a po... more The SA clothing industry shed over 67 000 jobs in the past three years (Bell, 2006).There is a possibility that more jobs may be shed in Durban (Kwa-Zulu Natal). The Alexander Report mentions that between July 2006 and May 2007 there was a drop of 5275 in employment figures (Palmi, 2007). The cut, make and trim (CMT) industries find it difficult to negotiate wage increases as production costs escalate beyond proportion. If the lay off of workers continues in the clothing industry, it would increase the unemployment rate, thus impacting on the economy. Statistics South Africa estimates that the South African population stands at approximately 47.4-million and the unemployment rate stands at 25% of the total population (www.southafrica.info).The clothing manufacturing industry is labourintensive with repetitive and skilled manipulation of fabric. With a challenge of skills development, SA faces a dilemma in terms of its productivity status. Poorly-designed workstations contribute to c...

Asian Journal of Agriculture and Rural Development, 2021

Compared to other countries, the level of agricultural mechanization in Africa and South Africa i... more Compared to other countries, the level of agricultural mechanization in Africa and South Africa is relatively low. Among the factors that influence agricultural mechanization, after-sales service of agricultural machinery is among the most significant. On the other hand, financial resources primarily impact on improvement and enhancement of after-sales service of farm equipment. In this paper, a questionnaire was employed as the method of quantitative data collection to assist in the analysis of data from 739 respondents in the Chinese context. Due to the Covid-19 pandemic in 2020 (Mmbengwa & Qin, 2020), no questionnaires were collected from South Africa for the purposes of this paper. A standard multiple regression analysis (MRA) was utilized to analyze the data collected from the structured questionnaires. Evidence from this study suggests that combining these financial resource factors has a major effect (F2 = 0.802) on the after-sales service of farm equipment. The high scores o...

South African Journal of Industrial Engineering, 2018

South African Journal of Industrial Engineering, 2016

Engineering Management Journal, 2017

South African Journal of Industrial Engineering, 2016

2015 Military Communications and Information Systems Conference (MilCIS), 2015

South African Journal of Industrial Engineering, 2018

This paper is an extension of previous research on the simulation of three technologies that inte... more This paper is an extension of previous research on the simulation of three technologies that interact in competition. Technology is considered as a result of innovation, a rate dependent process. Technology growth patterns can be traced in a number of ways. One interesting way that has been recently used very effectively is using bibliometrics as a data source for technology. In this paper the technology system is treated as a coupled system where the interacting dynamics is described by the Lotka-Volterra system of differential equations. The uncertainty in the interaction of the bridging technology with the mature defending technology and the newly introduced attacking technology is addressed in this research using a Monte Carlo multivariate simulation technique and a system dynamics approach. The research method is exploratory and case based a method that has been established as useful especially early on in research. Some exploration into cyclic behaviour of a modified version o...

American Society of Engineering Management 2015 International Annual Conference, Indianapolis, US... more American Society of Engineering Management 2015 International Annual Conference, Indianapolis, USA, 7-10 October 2015. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item

Computers & Industrial Engineering, Jun 18, 2012

2018 IEEE Technology and Engineering Management Conference (TEMSCON), 2018

In a complex mining environment sub processes are interlinked and dependent on each other. At eac... more In a complex mining environment sub processes are interlinked and dependent on each other. At each step of mining the actions of one heavily impact on the next process. The objective of this paper is to review the current mining environment and demonstrate whether it is possible to simulate a big surface mine in order to determine the impact of new technology or change of processes. The paper will discuss the approach taken to simulate the current and the future conditions. For this study, an openpit mine has been selected where iron ore is the only commodity. The initial aim of the broader study was to justify the need for drill rig automation in big mines and determine the value creation by means of simulation techniques. This paper will present the conceptual model developed to justify the need for automation specifically in the drilling process. The tool selected to achieve the objective is a System Dynamics tool called VENSIM. The process of creating the model and the logic behind the system dynamics is discussed. The conceptual model is presented with important focus areas in such a modelling attempt. Each mining process can be represented with stock and flow diagrams. The connections between each level is used to define the behavior of the system. A system will respond with three types of behavior; reaction, response and action. While reaction is sufficient, response is necessary when reaction is not sufficient. When this fails too, a change is required which is called an action. All these responses have a goal towards state-maintaining, goal-seeking and purposeful systems. State-maintaining systems often react to changes to maintain the state. A goal-seeking system is the one responds differently to a sequence of events until it reaches its purpose. A purposeful system can produce results in the same as well as different environments [5].

The aim of all companies is to increase their profitability and it is no different for the railwa... more The aim of all companies is to increase their profitability and it is no different for the railway environment. Possible steps toward obtaining this goal includes reducing costs, increasing productivity and efficiency. One focus area within the railway technical environment that can facilitate in obtaining these goals is maintenance. Even though conventional strategies such as corrective and preventive maintenance have proven to be lifesaving in some cases, it does not always adhere to the cost saving and process efficiency drives by companies. A new strategy of predictive maintenance is being investigated which is based on forecasting of system degradation through a prognostic process by using condition monitoring data. The objective of this paper is to propose a prognostic model which will be used for predicting the most cost and time effective maintenance schedule for a railway wagon based on the condition of its bogies, wheels, bearings and brake blocks.

South African Journal of Industrial Engineering, 2018

Indian Journal of Science and Technology, 2018

South African Journal of Industrial Engineering, Dec 1, 2016

International Journal of Learning and Change, 2021

A call centre is of strategic importance to an organisation and therefore needs to be developed w... more A call centre is of strategic importance to an organisation and therefore needs to be developed with ergonomics in mind. Call centre managers’ need to be trained in the field of ergonomics, so that an ergonomic “changeover” takes place to improve the workplace. Call centre agents are the lifeblood of the call center, and efficient managers need to do everything in their power to maintain a competitive workforce. The creation of worker friendly environment boosts the morale of the workforce, thereby reducing turnover and attracting professional agents. The issue of labour efficiency and productivity need to be addressed with the application of ergonomic principles which contribute process improvement. The result would be a reduction in absenteeism and worker's compensation claims as it is approximately ten million per year (www.statsa.org.za). Musculoskeletal disorders (MSDs) such as carpel tunnel syndrome arise from poor ergonomic practices. Thus, the focus of this article is to...

The SA clothing industry shed over 67 000 jobs in the past three years (Bell, 2006).There is a po... more The SA clothing industry shed over 67 000 jobs in the past three years (Bell, 2006).There is a possibility that more jobs may be shed in Durban (Kwa-Zulu Natal). The Alexander Report mentions that between July 2006 and May 2007 there was a drop of 5275 in employment figures (Palmi, 2007). The cut, make and trim (CMT) industries find it difficult to negotiate wage increases as production costs escalate beyond proportion. If the lay off of workers continues in the clothing industry, it would increase the unemployment rate, thus impacting on the economy. Statistics South Africa estimates that the South African population stands at approximately 47.4-million and the unemployment rate stands at 25% of the total population (www.southafrica.info).The clothing manufacturing industry is labourintensive with repetitive and skilled manipulation of fabric. With a challenge of skills development, SA faces a dilemma in terms of its productivity status. Poorly-designed workstations contribute to c...

Asian Journal of Agriculture and Rural Development, 2021

Compared to other countries, the level of agricultural mechanization in Africa and South Africa i... more Compared to other countries, the level of agricultural mechanization in Africa and South Africa is relatively low. Among the factors that influence agricultural mechanization, after-sales service of agricultural machinery is among the most significant. On the other hand, financial resources primarily impact on improvement and enhancement of after-sales service of farm equipment. In this paper, a questionnaire was employed as the method of quantitative data collection to assist in the analysis of data from 739 respondents in the Chinese context. Due to the Covid-19 pandemic in 2020 (Mmbengwa & Qin, 2020), no questionnaires were collected from South Africa for the purposes of this paper. A standard multiple regression analysis (MRA) was utilized to analyze the data collected from the structured questionnaires. Evidence from this study suggests that combining these financial resource factors has a major effect (F2 = 0.802) on the after-sales service of farm equipment. The high scores o...

South African Journal of Industrial Engineering, 2018

South African Journal of Industrial Engineering, 2016

Engineering Management Journal, 2017

South African Journal of Industrial Engineering, 2016

2015 Military Communications and Information Systems Conference (MilCIS), 2015

South African Journal of Industrial Engineering, 2018

This paper is an extension of previous research on the simulation of three technologies that inte... more This paper is an extension of previous research on the simulation of three technologies that interact in competition. Technology is considered as a result of innovation, a rate dependent process. Technology growth patterns can be traced in a number of ways. One interesting way that has been recently used very effectively is using bibliometrics as a data source for technology. In this paper the technology system is treated as a coupled system where the interacting dynamics is described by the Lotka-Volterra system of differential equations. The uncertainty in the interaction of the bridging technology with the mature defending technology and the newly introduced attacking technology is addressed in this research using a Monte Carlo multivariate simulation technique and a system dynamics approach. The research method is exploratory and case based a method that has been established as useful especially early on in research. Some exploration into cyclic behaviour of a modified version o...

American Society of Engineering Management 2015 International Annual Conference, Indianapolis, US... more American Society of Engineering Management 2015 International Annual Conference, Indianapolis, USA, 7-10 October 2015. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item