Leon Pretorius

• D Eng
• Professor Emeritus at University of Pretoria

In this article the aerodynamics of a rooftop greenhouse is evaluated using Computational Fluid Dynamics (CFD). This entails using a scale model and wind tunnel tests, as well as understanding the effects of design changes of the rooftop greenhouse on the aerodynamics. A wind tunnel test was conducted using a reduced scale model based on the full-s...

This research study assesses the maintenance practices on mining machinery as a case study in a surface platinum mine. The current literature commonly tends to highlight the significance of maintenance in respect to mining, yet it rarely provides specific analysis of various maintenance strategies and their effect on equipment performance in some s...

Decision making is central to project management practice. A project manager continually makes decisions from project inception to close-out. Having the appropriate decision making knowledge enhances the likelihood of the project manager making good and optimal decisions. The objectives of this paper are threefold. First, to investigate the differe...

This study uses empirical survey data to explore the impact of cognitive biases on sustainable decision-making within the Circular Economy (CE) through a System Dynamics (SD) analysis. The primary goal is to evaluate stakeholder rationality levels and investigate the utility of Behavioral System Dynamics (BehSD) in understanding the complex systems...

This paper provides a perspective on energy innovations in high-energy consuming sectors in South Africa. Despite South Africa’s high energy consumption, innovation adoption is sub-optimal. We investigated the research question: How are energy innovations implemented within high-energy consuming sectors in South Africa? Following an appropriate res...

Decision-making in companies is often based on the managers' personal experience. However, their consequences can have an impact on the development of the daily activities. To illustrate the managerial impact of decision-making, the biggest African power utility company based in South Africa will be analyzed. Various data such as annual productivit...

We live in a complex, artificial world that leads to complex, socio-technical problems. Systems thinking is advocated as one of the methods to approach and deal with such complex problems. This article revisits some critical systems thinking concepts and then applies them to a real-world problem using a thought experiment. The real-world problem se...

In today's ever-changing, unpredictable economy, it is crucial to understand stakeholder decision-making trends to ultimately change or better predict the system's behaviour in which they interact. Due to the COVID-19 pandemic, systems' economic changes and predictability changed so much that the term "new normal" emerged. A research gap currently...

The sustained use of eHealth is influenced by the dynamic and nonlinear interactions of technological, social, organisational and economic factors. However, most eHealth implementation frameworks are modelled linearly without capturing the complex relationship among elements of the ecosystem to ensure technology acceptance. The model-based theory-b...

After-sales service (ASS) plays a significant role following the agricultural machinery being sold. With the development of trade and economic exchange between South Africa and China. Chinese agricultural machinery has increasingly sold to South African and Africa. After-sales service becomes crucial important to maintenance the machinery. Results...

Cement is the world’s most important building material, and it has made Africa, as an emerging market, dependent on the cement industry as a critical tool to promote economic infrastructure growth. Today’s challenging economic climate has also made cement producers increasingly dependent on specialists to upgrade, modernise, and maintain their oper...

Eliciting the correct requirements for a particular product, project, or service is critical to the success of the endeavour. However, this has proved to be elusive in many projects. The ability to identify problems early in the requirements elicitation process early on can potentially be beneficial for the overall project. In an earlier paper, a m...

The pressure on systems engineering is ever‐increasing to support the development and implementation of systems that meet a complex environment's demands. As a growing discipline, systems engineering requires insight into past research to identify opportunities for future growth. Analyzing the bibliometric data on published research provides valuab...

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 aftersa...

There is a growing shift towards a circular economy as a society becomes more aware of the linear economy's influence on the ecology and sustenance of this ecosystem for the future generation. Digital technologies play an important role in the transition towards a circular economy by optimizing forward material flows and enabling reverse material f...

The use of competition as a conflict-handling style aimed at win-lose end results has been highlighted by some researchers to be common during project execution. However, the impact of such competition on project performance remains largely under-researched. This article seeks to address this gap in the existing literature. A system dynamics simula...

Since systems engineering is still a relatively young and growing discipline, it requires a periodic analysis, taking into account past research to derive the requirements for future growth. Published research provides a good indication on the progress and maturity of a scientific discipline. Bibliometric analysis is a valuable tool to assess publi...

Eliciting the correct requirements for a given product, project or service is crucial for the success of the endeavour. The requirements engineering process in general and the requirements elicitation process is fraught with pitfalls. This paper proposes a mechanism that can be used to model the requirements elicitation behaviour. The results of th...

This paper presents research relating to the challenges of conducting research in a complex, socio-technical system. The result of this research is that a conventional research approach is fundamentally reactive and does not always produce the desired results when applied to such a complex, socio-technical system. The literature suggests that appro...

Purpose Risk management has become an integral part in businesses around the world. In the construction industry, risk management has also been introduced and has been mainly entrusted in the hands of the project team to go through a laid down risk management processes to identify possible risk events, which may occur during the project execution a...

The present study concerns convective flows in the empty volume above the plant canopy in a confined greenhouse. The purpose of this paper is to numerically investigate the effect of the number of spans on the convective heat transfer in closed greenhouses. The initial greenhouse CFD model cavity is validated against experimental results found in t...

The paper can be downloaded free of charge from https://ascelibrary.org/doi/10.1061/%28ASCE%29WW.1943-5460.0000537 This paper presents the risk identification process, a checklist of 215 different risks, and an associated risk breakdown structure (RBS) for the design and construction phases for a shipping port and associated container terminal. Th...

The frequent failures of electronic health systems and lack of successful scale-up beyond pilot phase have been a concern for the implementation of electronic health systems in resource-constrained settings. Despite the challenges, developing countries have increasingly been implementing an electronic medical record system to improve patient care a...

After-sales service (ASS) is an important element after the production has been sold to the end-users also those who use agricultural machinery. This paper aims to review to some extent the ASS practice of Chinese agricultural machinery in cross-border e-commerce in Africa which has been an active practical and research topic in China, and for that...

Risk interaction changes the probability and impact of a given risk, which may result in a less effective risk response decision (RD). This study presents an approach for supporting the project manager in making RDs, comprising a simulation model of risk interaction network (RIN)for evaluating the RDs and an improved simulated annealing (SA)algorit...

This paper presents a model which uses the Monte Carlo method to quantify certain risk and project categories in a portfolio of 86 port and rail capital projects. The purpose of the model is to provide a portfolio-wide view of risks to answer the questions "What matters most?" and "Where should the focus be regarding risk treatment plans?". The ans...

This paper investigates the use of risk simulation to set project cost contingency guidelines for a programme of 84 port and rail capital projects. In this context, these guidelines refer to statements such as "Add 10% of the project capital cost as contingency to the estimate when going into project execution". In the research presented in this pa...

The objective of this paper is to derive the innovation profile in developing countries, such as South Africa, from a technology roadmapping practitioner’s point of view. The specific research questions that are addressed are i) what are the main priorities for innovation in South Africa? and ii) what are the actual or perceived innovation competit...

Central to project management is risk management — and the need to develop better and more specific tools to manage risk. This is driven by the desire to reduce uncertainty and risk on projects. Quantitative tools such as Monte Carlo simulation are sometimes used to analyse risk, but it is not clear how widespread, accepted, or useful such tools ar...

Railways have been used throughout history for the transportation of goods. Even though the inception of rail transport improved civilization, due to its inefficiencies, road transport is at present dominating the freight and logistics industry. Company A, which has the largest market share in the rail freight business, has embarked on projects to...

Project controls have been defined in the existing literature as managerial decisions and actions aimed at rectifying poor project performance. Understanding the potential unintended negative effects of such controls will be beneficial to project management practice and to the resulting project performance. Using the system dynamics approach, this...

There is evidence that several eHealth pilot projects in developing countries could not progress to full-scale implementation — sometimes referred to as the ‘pilotitis’ of the eHealth system. The sustainable eHealth implementation frameworks reported in the literature are linearly modelled, and fail to reflect the nonlinear and dynamic complexity o...

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 co...

The economic strategies are described as one of the key factors of long-term sustainability of eHealth implementation. The limited amount of budget and the short project duration of donor organizations present a threat to the large-scale and sustainable eHealth implementation in developing countries. The purpose of this study is to uncover the impa...

In this paper aspects of technology and entrepreneurship interaction are considered. Firstly some dy-namic aspects of technology are presented from a brief literature perspective. This is then contrasted to and integrated with some elements of entrepreneurship where cyclic aspects are influenced by un-employment in the business and possibly technol...

We live in an artificial world constructed of things that have been designed with a specific utility in mind. This utility aims to solve some problem or need that that is being experienced. Whereas natural and social science research is concerned with the explanation and prediction of observed phenomena and finding new truths or proofs as in “why d...

By studying the development status of cold chain logistics in China, and the current situation in the three specific industries of electronics commerce, supermarkets, and the food and beverage industry, this paper analyzes and concludes that the terminal logistics distribution capacity of the regional distribution centers in Chinese cities is insuf...

Risk analysis is an important fundamental basis of the decision-making process, and it has been applied in many fields. In order to improve the risk management of logistic, a new model based on particle swarm optimization (PSO) is proposed, which is a stochastic optimization method based on population. Through a comparison of performance with a Fuz...

Different project participants often have different objectives and expectations, and implement different controls aimed at advancing their interests. This article investigates project controls taken by the client during the project design stage to improve project time schedule performance. Dynamic hypotheses and a System Dynamics conceptual model o...

This article leverages a mathematical model of innovation for complex adaptive systems (CAS) to explore, ex post facto, organisational innovation investigations conducted by the first author at Stanford University Medical Center. Tapping into the meta-level and more varied sources of innovation, as illustrated by a generalised equation of innovatio...

The aim of this study is to improve the Technology Development Envelope (TDE) framework with the principles derived from a technology roadmapping framework for developing countries. The TDE framework focuses on emerging technology trends, organisation objectives and assessment of technology value based on the ability of individual technologies to a...

Nunes B., A. Emrouznejad, D. Bennett, L. Pretorius (2018) Towards Sustainable Technologies and Innovation, Proceedings of the 27th Annual Conference of the International Association for Management of Technology, Aston University, ISBN 978 1 85449 453 5. http://www.aston.ac.uk/aston-business-school/iamot2018/proceedings/

This article will suggest a mathematical model for the strong connection between light and matter. Proposed properties of light will be shown to the birth matter at any level of complexity. A conceptual analytical model is constructed to elaborate the structure of light and its link with matter. Consistent with the genre of modern-day theoretical m...

The main aim of technology development and innovation is to deliver a new or improved product or service that will allow a company to maintain or increase its market share. This improvement in market share will only occur if the companies truly understand the customers’ needs. This need is expressed as requirements that will form the basis of the p...

This research paper focused on formulating dynamic hypotheses and a System Dynamics conceptual model of an engineering consultant’s project revenue controls and associated ripple effects from a combination of: causal networks generated using ATLAS.ti from a case study’s qualitative data; extant literature; and System Dynamics’ Systems Thinking tool...

Oceans of Innovation explores the mathematical heart of complex systems. The exploration begins with uncovering the nature of a point in space-time, which is seen to be a function of the orders implicit in time and space. So naturally any point is imbued with innovation-potential. Subsequently a mathematics is developed to suggest how innovation-po...

Greenhouses are used worldwide to grow various types of plants in climates and seasons not usually adequately suited for optimum growth. The microclimate inside greenhouses is of major importance as it directly affects the quantity and quality of crop production. Ventilation is a vital mechanism for maintaining an acceptable indoor climate for opti...

Many risks emerge in logistics projects. These risks pose a direct or indirect threat to the results of these projects. In China, project management has only recently been introduced to the logistics industry, so little research has been conducted on the risk management of logistics projects. Studying domestic and overseas logistics project managem...

When introducing quantified risk assessments at a South African state-owned freight company, a skills gap was found during the identification and quantified risk analysis. To help with risk identification, a checklist of risks for railway construction projects was developed. The basis of this checklist was 38 individual railway construction project...

Requirements engineering remains a complex process with many opportunities to introduce errors into the requirements elicited. These errors, if not discovered in time, can lead to a failed or challenged project. The requirements elicited from stakeholders remains the most problematic and prone to error compared to the requirements elicited from oth...

Abstract: Successful implementation of electronic health (eHealth) is affected by several interrelated factors that go beyond technological elements. Economic, social (human) and environmental (organizational) factors significantly influence the sustainability of eHealth systems. Because of organizational factors, the same eHealth system can exhibi...

Extant literature shows different measures for business performance of a ‘for-profit’ organisation; including both financial performance and non-financial dimensions. Key financial performance measures, evident in existing literature, include: profit; revenue; cash flow; and return on investment, among others. Some previous scholars highlighted tha...

This paper combines various concepts related to (i) project risk management, (ii) Monte Carlo simulation, (iii) project contingency cost estimation, and (iv) the relationship between project and programme risks, to illustrate that the contingency requirements are lower when simulating all the risks in the programme when comparing it with the indivi...

System Dynamics models have previously been used to describe the adoption of new technology in Healthcare. JB Homer and later KL Knoll developed such models based on case studies involving implantable devices and antibiotic pharmaceutical product. In both cases the technologies studied were of a therapeutic nature and the use-event was linked to an...