Leon Pretorius

A theoretical and experimental study was carried out to investigate the possibility of separating solid-liquid suspensions of water and talcum powder, as well as in a process cooling water system, by means of a standing ultrasonic acoustic wave. Separation was successfully achieved with suspensions of water and talcum powder. The separation of suspended solids from the process cooling water was unsuccessful owing to the extremely small sizes of the suspended solid particles. a_~_ e~ E= F(po/ p,) = f= h= K(k)2/n = k= P= r..~. T= U ~ 2= /t= po pl-= NOMENCLATURE diameter of particles (mm) velocity of sound in water (m/s) energy density of the acoustic field (Nm/m 3) density fi~ctor frequency (Hz) reference position measured from node or antinode (m) amplitude factor 2rt/wavelength (m ~) radiation pressure (N) radius of particles (mm) time per~tod for movement of a particle to a node or antinode(s) particles velocity (m/s) wavelen~;th (mm) viscosity (kg/m.s) density of fluid (kg/m 3) density of particles (kg/m 3~

The possible effect of a pandemic on education is conceptually addressed in this paper. The arrival of Corona virus (CoVid 19) as one form of such a pandemic in South Africa has exposed and accelerated the trend of growing disparities in basic education system between private and the vast majority of public schools. The advent of lockdown regulations brought by various governments in the world and South African government in particular has accelerated development of e-learning and e-content creation by private education providers. Whereas Face-to -face offerings are still preferred, blended education has increased dramatically with more e-content likely to be the game changer and enabler of the long awaited 4IR relevant education outcome in SA in particular as addressed in this paper. Whilst this development is positive for basic education, the advent of lockdown brought by CoVid 19 pandemic, has also highlighted that the difference in access to technology between poor and rich schools could translate at a basic level to a huge gap in available classroom instruction times which is a fundamental element of the required learning environment. In 2020, South African schooling calendar experienced major disruption due to lockdown regulations however, rich schools were able to mitigate this impact through e-learning platforms, something not possible currently for poor schools. This paper seeks to conceptually establish the unique impact of technology application on the outcome of basic education in South Africa. We make a comparison to the trends of the past 9 years and contrast this with the results of the 2020 school year under CoVid 19 pandemic restrictions. We argue in this paper, that though not the only element of advantage, access to e-learning and e-content can be a big contributor to the difference in performance of high school pupils in basic education. The paper demonstrates that the ability to use technology and e-content creates the major difference between poor and exceptional/resilient education system. We believe that as was demonstrated during lockdown by business and higher learning institutions, creating more access to e-learning platforms material and virtual classrooms for children in remote areas can mitigate against any disruptions due to the macro environment and enhance the ability of the system to transform education from passive learning (teach and absorb type) to an active learning (stimulation based and research type) that is most relevant to the 4IR era. Copyright © 2021 by Naudé Scribante. Permission granted to IAMOT to publish and use.

Health Technology is at the core of delivering quality healthcare service in many environments. To this end, the adoption of innovation plays an important role in ensuring the most current solutions are consistently applied in diagnosis and treatment. This paper reviews some of the emerging factors that influence the diffusion of health technology. The aim is to identify the new factors, which can be used to extend previous research in the field of modelling diffusion of innovation quantitatively through the application of System Dynamic analysis. A further dimension of the study is to see how a resource constrained environment would impact on diffusion of innovation. The paper concludes with listing a number of these factors and how they can be incorporated into future research.

Abstract: A Case study company that was set up as a project where the technical focus, activities and behaviour set the initial culture is considered in this research. Over a period of 11 years the Case study engineering organisation was exposed to many influences in the electrical utility industry that now give lead to questions such as: How did events influence the engineering culture and how did the culture change over time? Engineering organisations are subjected to external and internal events which are not always within their control. These include technological changes, economical changes or new competition, change in ownership, business focus or technical leadership. The ability to absorb such events is not only a function of the organisation's technology infrastructure, availability of funding or skills, but also of the organisational culture prevailing at the time. The objective of the research is to determine how eight events impacted the culture of an engineering or...

Risk interactions exist within a system and its sub-systems, between functional and physical elements in various dimensions such as spatial interaction, information exchange, material transfer, and energy exchange. These interactions are of a multi-dimensional complexity, and thus are not sufficiently interpreted using conventional management tools. Alternative system representation and analysis techniques are proposed – in particular the design structure matrix (DSM) and fuzzy logic thinking – to quantify the risk management effort necessary to deal with uncertain and imprecise interactions. A cement grinding plant case study is used to elaborate on the risk management methodology OPSOMMING Risiko-interaksies bestaan binne ’n stelsel en sy sub-stelsels, tussen funksionele en fisiese elemente. Hierdie interaksies kan gekwantifiseer word in ’n ruimtelike, inligting-uitruiling, materiaal-oordrag of energie-uitruiling raamwerk. Die interaksies is van ’n multi-dimensionele kompleksiteit...

The role that project risk management plays in ensuring the successful delivery of engineering and construction projects in South Africa is addressed in this paper. A survey questionnaire was developed to establish approaches used for risk management, and tools and techniques for risk identification. The findings revealed that project risk management had a significant role to play in the success of projects in South Africa. Respondents whose organisations practised structured risk management processes reported success in their projects. The main challenge was found to be in the implementation of risk management tools and techniques. Thus it became apparent that widespread adoption of project risk management in South Africa seemed to be impeded by a low knowledge and skills base, especially in terms of its application. OPSOMMING Die rol wat projekrisikobestuur in die suksesvolle aflewering van ingenieurs- en konstruksieprojekte in Suid-Afrika speel word hier aangespreek.’n Vraelys is...

A systems approach to creating a system is discussed. The system engineering process, and specifically the system architecture process, is formulated and applied to a typical (physical) system, enterprise, and project. These lead to the concepts of system architecture (SA), enterprise architecture (EA), and project architecture (PA) respectively. Similarities and inter-relationships among these architectures and related methodologies are investigated, seeking better interaction among them. ‘Work ’ is proposed as an important conceptual building-block of these architectures, properly defined as activity with associated inputs, outputs, governances, and mechanisms. Techniques such as functional analysis, process modelling, and task analysis are used to demonstrate the inter-relationships among these apparently unrelated organisational perspectives of product, process, and project. OPSOMMING ’n Stelselbenadering tot die daarstelling van ’n stelsel word bespreek. Die stelselingenieurs-w...

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...

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 technology environment. This work is built on some views presented by previous authors such as Faria and others. Their work is extended to a conceptual sys-tems thinking model representing cyclic factors in entrepreneurship using a causal loop diagram (CLD) approach. Some business statistics from databases are gathered and analysed for entrepre-neurship to show and support some arguments of Faria and others about cyclic nature of entrepre-neurship. A conceptual system dynamics approach for the entrepreneurship dynamics is presented based on previous research.

The aim of the research was to develop an Effective Management Model (EMM) for a Gland Service System (GSS). The Systematic Approach to Engineering Design focuses on the optimisation of the GSS which is a fundamental pillar for the functionality of the slurry pumps in a tailings plant. The EMM was considered for a wide variety of mining applications to innovatively create a method for the correct design, implementation, control and maintenance of a Gland Service System. A Production Performance Model (PPM) was created utilising the Overall Equipment Effectiveness (OEE) Theory to provide an indication of the production capacity of a tailings plant. The subsystem of the PPM was the EMM, its core focus was on the optimisation of the Gland Service System, which in turn directly relates the improved performance of the tailings plant which ultimately results in the improved capability of the mines production process. Simulink was used to incorporate the optimisation inputs of the GSS, thu...

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 dependant 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...

In this paper the climate inside a greenhouse subject to various vent configurations is investigated. The greenhouse considered is a four span glass greenhouse, containing a plastic partition separating the greenhouse into two compartments. The temperature and velocity distribution at plant level is numerically analyzed with computational fluid dynamics. Six cases were considered. The first three cases have the roof vents open to the leeward side, while the side ventilators are opened at 30° and 45° respectively, after which a second row of side ventilators opened at 45° were added to the geometry. The last three cases have the roof vents open towards the windward side, with the same side ventilator configuration as mentioned for the first three simulations. Contour plots for both temperature and velocity are discussed and analyzed. Results seem to indicate that the temperature and velocity at plant level are significantly influenced by the arrangement and number of vents. The prese...

The loss of skills and knowledge of technical professionals experienced by many organisations in South Africa has serious implications for the local and international competitiveness of these organisations. Research has indicated that there are fundamental differences between technical professionals and other staff in organisations, so that they need to be managed in a different way. Retaining talent calls for innovative human-resource practices. This article discusses various management and retention strategies

The purpose of this paper is to investigate and compare the indoor climate of detached and connected greenhouses. The velocity and temperature distribution inside these greenhouses are numerically analysed using computational fluid dynamics. The initial four span greenhouse was validated in a previous paper [10]. In the first case evaluated, a second greenhouse was placed behind the first greenhouse. Secondly, the first four span greenhouse was extended by adding four additional spans, creating an eight span greenhouse. Lastly, the first case was extended by moving the second greenhouse to the leeward side so as to create a distance of 2m between them. Results showed that by adding an additional four spans, or by attaching four extra spans, the indoor climate inside the greenhouse is influenced to some extent. If the velocity and temperature distributions in the first four and last four spans are compared, a notable difference is found which may influence crop growth. INTRODUCTION V...

This paper analyzes the definition and division of modern logistics in the logistics industry, and expounds the project management model faced by logistics issues in the transitional period. It further analyzes and interprets project management in the logistics industry, regulates and annotates the meaning of the project, and defines its specific operation contents as "5 + 1", which extracts the theoretical basis and practical needs of the project risk management mechanism. The risk categories are divided into two major categories, four sub-categories, eight classifications and 24 sub-items. Furthermore the probability of various risk occurrences is initially established and then the evaluation methods as well as responding solutions against various degrees of losses are designed so as to establish a set of independent risk prevention and control mechanisms for the logistics project - Five Steps Risk Management and "network" risk control mechanism. This study is ...

In this paper a numerical study of two-dimensional conjugate natural convection in square cavity containing heated cylinders and outer isothermal boundaries is performed. The cavity is designed to simulate an unfilled trough containing electrical cables. The purpose of this paper is to investigate the effect of geometrical arrangements of electrical cables in underground cable ducts on the heat transfer from the cables. The numerical investigation is performed using Computational Fluid Dynamics. Asymetric flow around the cables caused the temperature distributions around the cables for the different geometric arrangement to be dissimilar. The local Nusselt number around the cables was a function of the angle (θ), and the Nusselt number distributions vary for each cable and arrangement. The diagonal arrangement was found to be the least favourable, as this arrangement leads to higher temperatures in the cables compared to the vertical and horizontal arrangement.

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 individual project contingency requirement. A case study organisation provided 86 quantified risk registers related to port and rail capital projects. For each of these risk registers, the project contingency was estimated using a prescribed risk register template and Monte Carlo simulation software. The same 86 quantified risk registers were then used to simulate the programme contingency. The simulation results indicated that the programme contingency requirement was approximately 8% points lower than that of the sum of the individual projects. The first implication of this research result is that, should borrowed capital be used to fund the p...

Research efforts using system dynamics to understand and evaluate societal and policy-related problems in Southern Africa are becoming essential. This paper undertook a systematic review to examine the extent of utilization of system dynamics in Southern Africa between 2003 and 2014. The results showed that system dynamics has been used, or referred to, in the academic literature pertaining to the themes of environment, public policy and resources. Nevertheless, focuses remain limited in its application across various industries, particularly relating to stakeholder engagement and strategy. However, some analysis of the non-academic literature suggests that commercial practice of system dynamics has a different trend, where it is mainly used for strategic and tactical projects, mostly for industry clients. Thus, the current research outputs do not necessarily reflect the industry needs. This review is then useful to facilitate further discussions on practical applications of system dynamics through the South Africa System Dynamics Chapter. Copyright © 2016 John Wiley & Sons, Ltd.

It is apparent that understanding the link between the role of innovation in competitiveness and economic development is essential. This is because innovation ultimately holds the key to addressing the most pressing a nation’s social and human challenges. In the past, some organizations viewed research and development (R&D) as an intangible, difficult to manage and measure process and do their best to stay away from it. On the other hand, organizations that have a clear understanding and mastery of R&D management seem to have great success in exploiting R&D in commercializing new technologies with speed and precision that enabled them to achieve numerous competitive edge, such as first-to-market advantages, greater market shares for their innovations, premium prices and dominant designs relative to their counterparts). However, the upsurge in enabling technologies such as the internet is changing the perceptions on managing R&D processes, moving from technology-oriented model to a m...

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 improve rail efficiencies by moving higher volumes of freight timeously. Most of the projects embarked on by Company A have failed largely due to the poor planning of the projects in the feasibility stages. Most of the planning schedules are overoptimistic and unrealistic making them unreliable and difficult to track. The scope of this study was to investigate the way in which planning schedules of Company A are developed by undertaking a schedule risk analysis on one of the planning schedules titled 'Design of railway exchange yard' and using Monte Carlo simulation to validate the schedule. If projects of Company A can be planned ...

Purpose The purpose of this paper is to explore what underlies the development of the consumer 3D printing industry and gain insight into future developments and its potentially disruptive impact on the existing manufacturing industry. Design/methodology/approach A combination of approaches was followed. Initially a consumer 3D printer was purchased to gain first-hand experience as part of a practical research case study. Results were discussed with manufacturers and additional information was sought, and triangulated, via a survey and an exploratory bibliometric study. Findings Many characteristics are in place to identify consumer 3D printing as a potential disruptive technology for the manufacturing industry. For example, the cost of consumer 3D printing is lower than for traditional manufacturing. However, the current adoption rate is low and the user friendliness and technological capabilities need to improve. Research limitations/implications The main limitation is the explora...

Purpose The purpose of this paper is to gain insight into whether additive manufacturing (AM) represents incremental, radical, disruptive innovation or an industrial revolution and its implications. Design/methodology/approach This study applies a desk research strategy. Data were collected through a variety of industry sources as well as academic publications. Findings It was found that AM represents different innovations in different settings, while it represents incremental innovation in one industry, it has led to radical changes in other industries. There are also indications that it has a disruptive nature and some of the developments appear to be of the industrial revolutionary type, i.e. they cause fundamental shifts in society. Some explanation for the observed differences can come from different performance objectives. Research limitations/implications The spread of AM has been limited due to initial intellectual property protection. That means that while illustrations and...

The purpose of IPTS is to unite the core project participants (those 20% of project participants responsible for 80% of the impact on the project success) with a common goal, so that they focus on what is in the interest of the project and not on their company's interest or local optimisation. Like a tripod, Integrated Project Team Strategies (IPTS)