published_or_final_version / Industrial Engineering / Master / Master of Science in Engineering

M.Phil. / The aim of this research is to study the underhood airflow thermal behaviour of the extra low profile (XLP) dozer due to the excessive heat dissipated and observed during testing sessions executed at ground level, using computational fluid dynamics (CFD). The motivation of this project is to identify the reasons of poor cooling performance of this equipment, to develop and to demonstrate the capabilities of CFD in thermal research by validating the CFD result with experiments using a scaled model, prior to analyzing the full-scale dozer ...

Thesis (PhD (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2004. / Granular flow occurs in a broad spectrum of industrial applications that range from separation and mixing in the pharmaceutical industry, to grinding and crushing, blasting, stockpile construction, flow in and from hoppers, silos, bins, and conveyer belts, agriculture, mining and earthmoving. Two totally different approaches of modelling granular flow are the Discrete Element Method (DEM) and continuum methods such as Finite Element Methods (FEM). Continuum methods can be divided into nonpolar or classic continuum methods and polar continuum methods. Large displacements are usually present during granular flow which, without remeshing, cannot be solved with standard finite element methods due to severe mesh distortion. The Particle-in-Cell (PIC) method, which is a so-called meshless method, eliminates this problem since all the state variables are traced by material points moving through a fixed mesh. The main goal of this research was to model the flow of noncohesive granular material in front of flat bulldozer blades and into excavator buckets using a continuum method. A PIC code was developed to model these processes under plane strain conditions. A contact model was used to model Coulomb friction between the material and the bucket/blade. Analytical solutions, published numerical and experimental results were used to validate the contact model and to demonstrate the code’s ability to model large displacements and deformations. The ability of both DEM and PIC to predict the forces acting on the blade and bucket and the material flow patterns were demonstrated. Shear bands that develop during the flow of material were investigated. As part of the PIC analyses, a comparison between classic continuum and polar continuum (Cosserat) results were made. This includes mesh size and orientation dependency, flow patterns and the forces acting on the blade and the bucket. It is concluded that the interaction of buckets and blades with granular materials can successfully be modelled with PIC. In the cases conducted here, the nonpolar continuum was more accurate than the polar continuum, but the polar continuum results were less dependent on the mesh size. The next step would be to apply this technology to solve industrial problems.

Automated data acquisition has revolutionized the reliability of product design in recent years. A noteworthy example is the improvement in the design of aircrafts through field data. This research proposes a similar improvement in the reliability of process design of earthmoving operations through automated field data acquisition. The segment of earthmoving operations addressed in this research constitutes the truck-loader operation. Therefore, the applicability of this research extends to other industries involving truck-operation such as mining, agriculture and forest logging and is closely related to wheel-based earthmoving operations such as scrapers. The context of this research is defined by data collection needed to increase the validity of the results obtained by analysis tools such as simulation, performance measures and graphical representation of variance in an activity's performance, and the relation between operating conditions and the variance in an activity's performance. The automated cycle time data collection is facilitated by instrumented trucks and the collection of information on operating conditions is facilitated by image database and paper forms. The cycle time data and the information on operating conditions are linked together to form the experience database. This research developed methods to extract, quantify and understand the variation in each component of the earthmoving cycle namely, load, haul and return, and dump activities. For the load activity, the simultaneous variation in payload and load time is illustrated through the development of a PLT (PayLoad Time) Map. Among the operating conditions, material type, load area floor, space constraints and shift are investigated. A dynamic normalization process of determining the ratio of actual travel time to expected travel time is developed for the haul and return activities. The length of the haul road, sequence of gear downshifts and shift are investigated for their effect on the travel time. The discussion on the dump activity is presented in a qualitative form due to the lack of data. Each component is integrated within the framework of the experience database. The implementation aspects with respect to developing and using the experience database are also described in detail. The practical relevance of this study is highlighted using an example. / Ph. D.

Thesis (MBA)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Richards Bay Minerals (RBM) went through a restructuring process in 2002. The effect that these changes had on the life expectancy of the heavy earthmoving equipment (HEME) at the company’s sand dune mining operation situated at Richard’s Bay on the north coast of KwaZulu-Natal, was unknown. This study explores these, and various other factors, that influence the life expectancy of the HEME in this highly corrosive environment. During the last number of years there has been no equipment replacement philosophy at RBM and this has resulted in the average age of HEME at the mine being extremely high. This study suggests that when restructuring is implemented in the wrong way, the process can have significant negative implications. The study determines how the behaviour of especially drivers and maintenance personnel (maintainers) impacts on the expected life of the HEME at RBM. The hidden cost element of driver and maintainer unhappiness, however, is not included as part of this study. In the first part of this study project, the writer focuses on what may have caused the unhappiness, and makes suggestions for further studies aimed at addressing this unhappiness and changing the behaviour of drivers and maintainers. These suggestions should be seen as guidelines, as measures that work in one company may not necessarily work in another. The second part of the study project deals with the replacement philosophy regarding HEME at RBM. The mine has various types of equipment, but the main focus of this research falls on the following: Caterpillar 966- 980 (payloaders), track type equipment Caterpillar D7R/H (dozers), Caterpillar 988- 992 (heavy duty payloaders) and Bell B25 articulated dumptrucks (dumptrucks) Four different replacement models are investigated and discussed in detail. The model that was best aligned with the Caterpillar proposed best replacement practice, as stipulated by the Caterpillar replacement expert, is identified. Finally, a replacement cycle for the different types of equipment is proposed. / AFRIKAANSE OPSOMMING: Richardsbaai Minerale (RBM) het in 2002 deur ‘n herstruktureringsprogram gegaan. Die uitwerking wat die gevolge daarvan op die swaar grondverskuiwingsvoertuie (SGV) gehad het was onbekend. Gedurende die laaste aantal jare was daar geen vervangingsbeleid by RBM nie, en dit het meegebring dat die gemiddelde ouderdom van die SGV op die myn buitengewoon hoog is. Dit is belangrik om te bepaal wat die invloed van menslike gedrag van veral die drywers en herstelpersoneel op die verwagte leeftyd van SGV is. Die versteekte koste wat verbind word met ongelukkige drywers en herstelpersoneel maak nie deel uit van hierdie studie nie. As herstrukturering op die verkeerde manier toegepas word kan dit ‘n negatiewe impak hê. In die studie sal daar aandag gegee word aan wat die negatiewe elemente is en wat is die moontlike oorsaak daarvan. Daar word ook sekere voorstelle gemaak vir toekomstige studies om die ongelukkigheid aan te spreek en ‘n gedragsverandering na vore te bring. Die voorstelle is slegs riglyne en, wat in een maatskappy werk sal nie noodwendig in ‘n ander een werk nie. Die tweede deel van die werkstuk fokus op vervangingsteorieë met betrekking tot die SGV op RBM. Die myn het verskeie tipes SGVs maar die fokus het geval op vier soorte SGV. Hulle is Caterpillar 966- Caterpillar 980 (gemiddelde laaiers), spoor tipe toerusting Caterpillar D7R/H (stootskrapers), Caterpillar 988- Caterpillar 992 (swaargewig mobiele laaiers) en Bell B25 geartikuleerde stortings trokke (stortings trokke). Vier verskillende modelle is ondersoek en deeglik bespreek. Die model met die beste uitslae wat die mas opgekom het ten opsigte van die Caterpillar se voorgestelde beste vervangings praktyk, soos aangedui deur die Caterpillar voertuig vervangings kenner, is ge-identifiseer. Laastens word die vervangingsiklus vir die verskillende tipes toerusting voorgestel.

Major changes that emphasise the importance of a balanced work and family life have occurred within organisations. Inability to manage this integration between the work and home domains can affect the performance of organisations and the wellbeing of their employees. In order to measure work-home interaction and wellbeing, it is important to use valid, equivalent and reliable instruments. However, there is a lack of empirical research when investigating work-home interaction, burnout and work engagement in the earthmoving equipment industry in South Africa. Furthermore, the earthmoving equipment industry is a multicultural environment and construct equivalence across subgroups therefore becomes important when measuring work-home interaction, burnout and work engagement across different cultural or language groups. It also seems relevant to consider differences in the work-home interaction and work wellness levels between important demographic groups in the earthmoving equipment industry. It appears as if burnout and engagement can be seen as part of the total wellness continuum; and that job characteristics may be related to burnout and engagement through negative and positive work-home interaction. However, little information was found that included these factors in a structural model for the earthmoving equipment industry. The objectives of this research were to test the psychometric properties of the Survey Work- Home Interaction - Nijmegen (SWING), the Maslach Burnout Inventory - General Survey (MBI-GS) and the Utrecht Work Engagement Scale (UWES); to determine if various demographic groups differ with regard to work-home interaction and wellbeing; and to test a structural model that includes job characteristics, work-home interaction and wellbeing for employees in the earthmoving industry. A cross-sectional survey design was used. Random samples (n = 528) were taken from employees in the earthmoving equipment industry in Gauteng, the Limpopo Province, Mpumalanga, the Northern Cape, the Western Cape, the Eastern Cape, Kwa-Zulu Natal and the North West Province. Structural equation modelling confirmed a four-factor model of work-home interaction which measures negative work-home interference, positive work-home interference, negative homework interference and positive home-work interference. This factor structure was equivalent across language, ethnicity, gender, education, marital status and parental status. All four factors were reliable. The participants reported more negative WHI than negative HWI, and more positive HWI than positive WHI. It was found that statistically significant differences that are based on age, gender, language, ethnicity, a partner's contribution to household income and the different business units exist between the demographic groups. The results confirmed a four-factor structure of burnout (exhaustion, cognitive weariness, cynicism and professional efficacy) and a two-factor structure of work engagement (including vigour and dedication). These structures were equivalent across language and education groups, and all scales were reliable. SEM analyses supported a two-factor structure for the wellness construct, consisting of burnout (exhaustion, cognitive weariness and cynicism) and engagement (vigour, dedication and professional efficacy), which was equivalent for the language and education groups. Statistically significant differences that are based on age, gender, language and the different business units were found between the demographic groups. Structural equation modelling showed that job demands are associated with negative WHI and consequently with burnout, providing support for a full-mediation effect of negative WHI. Job resources were associated with negative WHI and consequently with burnout, providing support for partial mediation of negative WHI between job resources and burnout. Job resources were also associated with positive WHI and consequently with engagement, providing support for partial mediation of positive WHI between job resources and engagement. Recommendations for the organisation and future research were made. / Thesis (Ph.D. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2007.

The thesis focuses on evaluating and improving the transport efficiency of two types of logistics operations in the supply chain. One research area is the production of raw material in construction operations, specifically earthmoving operations. Methods and tools are developed to provide decision support in improving the transport efficiency of earthmoving at the vehicle and the systems levels. Using known road topography and a GPS unit, an optimal control problem is formulated and solved (Paper III) to determine the optimal gear shift sequence and timing in order to improve the transport efficiency at the vehicle level. For decision support at the systems level, a Fleet Performance Simulation (FPS) model is designed (Paper IV) to evaluate the transport efficiency for a given mix of construction vehicles in earthmoving. The FPS system is integrated with an optimization algorithm to solve the optimal fleet composition problem for earthmoving operations (Paper V &amp; VI). Construction operations are dynamic and the environment is changing constantly, which bring difficulties in decision-making. Using GPS data from construction vehicles, a map inference framework (Papers I &amp; II) is developed to automatically extract relevant input to decision support at the vehicle and the systems levels, which include the locations of various workstations, driving time distributions and road networks. The second research area is the transport efficiency of urban distribution system, which is in the final phase of the supply chain. An off-peak delivery pilot project in Stockholm is used as the background, designed to evaluate the potential for commercial vehicles to make use of off-peak hours for goods delivery. The thesis (Paper VII) evaluates the transport efficiency impacts of the off-peak pilot. An evaluation framework is defined where transport efficiency is studied in a number of dimensions. GPS data, fleet management data, and logistic information are used to assess the impacts. / <p>QC 20170323</p>

In an ever-changing world, people are constantly faced with the challenge of simultaneously managing multiple roles in their work as well as their home-sphere. It therefore becomes increasingly important to maintain a balance in these two life spheres. Unfortunately, a gap exists between the positive and negative side of work-home balance as most research focuses on the negative side. Recently, a much needed instrument was develop in the Netherlands, namely the Survey Work-Home Interaction - Nijmegen (SWING), which measures both the direction of influence (work→home and vice versa) and the quality of influence (negative vs. positive). The objectives of this study were to validate the Survey Work-Home Interaction - Nijmegen (SWING) for workers of the earthmoving equipment industry in a South African context, to determine its construct equivalence and bias for different language groups, and to determine differences regarding work-home interaction between different demographic groups. A cross-sectional survey design was used. Random samples (n = 330) were taken of workers in the earthmoving equipment industry across South Africa. The SWING and a biographical questionnaire were administered. Item bias analyses, exploratory factor analysis, Cronbach alpha coefficients, MANOVAs, ANOVAs and T-tests were used to analyse the data. Exploratory factor analysis showed that the SWING consists of four factors, namely Negative Work-Home Interference, Negative Home-Work Interference, Positive Work-Home Interference and Positive Home-Work Interference. All four factors showed acceptable internal consistencies. No evidence was found for uniform or non-uniform bias of the items of the SWING for different language groups. Exploratory factor analysis with target rotations confirmed the construct equivalence of the work-home interface construct. There were also no differences regarding work-home interaction between different demographic groups, except for a practically significant difference (medium effect) between males and females with respect to negative Work-Home Interaction levels. Recommendations were made for further research. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2005.

In an ever-changing world, people are constantly faced with the challenge of simultaneously managing multiple roles in their work as well as their home-sphere. It therefore becomes increasingly important to maintain a balance in these two life spheres. Unfortunately, a gap exists between the positive and negative side of work-home balance as most research focuses on the negative side. Recently, a much needed instrument was develop in the Netherlands, namely the Survey Work-Home Interaction - Nijmegen (SWING), which measures both the direction of influence (work→home and vice versa) and the quality of influence (negative vs. positive). The objectives of this study were to validate the Survey Work-Home Interaction - Nijmegen (SWING) for workers of the earthmoving equipment industry in a South African context, to determine its construct equivalence and bias for different language groups, and to determine differences regarding work-home interaction between different demographic groups. A cross-sectional survey design was used. Random samples (n = 330) were taken of workers in the earthmoving equipment industry across South Africa. The SWING and a biographical questionnaire were administered. Item bias analyses, exploratory factor analysis, Cronbach alpha coefficients, MANOVAs, ANOVAs and T-tests were used to analyse the data. Exploratory factor analysis showed that the SWING consists of four factors, namely Negative Work-Home Interference, Negative Home-Work Interference, Positive Work-Home Interference and Positive Home-Work Interference. All four factors showed acceptable internal consistencies. No evidence was found for uniform or non-uniform bias of the items of the SWING for different language groups. Exploratory factor analysis with target rotations confirmed the construct equivalence of the work-home interface construct. There were also no differences regarding work-home interaction between different demographic groups, except for a practically significant difference (medium effect) between males and females with respect to negative Work-Home Interaction levels. Recommendations were made for further research. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2005.

Major changes that emphasise the importance of a balanced work and family life have occurred within organisations. Inability to manage this integration between the work and home domains can affect the performance of organisations and the wellbeing of their employees. In order to measure work-home interaction and wellbeing, it is important to use valid, equivalent and reliable instruments. However, there is a lack of empirical research when investigating work-home interaction, burnout and work engagement in the earthmoving equipment industry in South Africa. Furthermore, the earthmoving equipment industry is a multicultural environment and construct equivalence across subgroups therefore becomes important when measuring work-home interaction, burnout and work engagement across different cultural or language groups. It also seems relevant to consider differences in the work-home interaction and work wellness levels between important demographic groups in the earthmoving equipment industry. It appears as if burnout and engagement can be seen as part of the total wellness continuum; and that job characteristics may be related to burnout and engagement through negative and positive work-home interaction. However, little information was found that included these factors in a structural model for the earthmoving equipment industry. The objectives of this research were to test the psychometric properties of the Survey Work- Home Interaction - Nijmegen (SWING), the Maslach Burnout Inventory - General Survey (MBI-GS) and the Utrecht Work Engagement Scale (UWES); to determine if various demographic groups differ with regard to work-home interaction and wellbeing; and to test a structural model that includes job characteristics, work-home interaction and wellbeing for employees in the earthmoving industry. A cross-sectional survey design was used. Random samples (n = 528) were taken from employees in the earthmoving equipment industry in Gauteng, the Limpopo Province, Mpumalanga, the Northern Cape, the Western Cape, the Eastern Cape, Kwa-Zulu Natal and the North West Province. Structural equation modelling confirmed a four-factor model of work-home interaction which measures negative work-home interference, positive work-home interference, negative homework interference and positive home-work interference. This factor structure was equivalent across language, ethnicity, gender, education, marital status and parental status. All four factors were reliable. The participants reported more negative WHI than negative HWI, and more positive HWI than positive WHI. It was found that statistically significant differences that are based on age, gender, language, ethnicity, a partner's contribution to household income and the different business units exist between the demographic groups. The results confirmed a four-factor structure of burnout (exhaustion, cognitive weariness, cynicism and professional efficacy) and a two-factor structure of work engagement (including vigour and dedication). These structures were equivalent across language and education groups, and all scales were reliable. SEM analyses supported a two-factor structure for the wellness construct, consisting of burnout (exhaustion, cognitive weariness and cynicism) and engagement (vigour, dedication and professional efficacy), which was equivalent for the language and education groups. Statistically significant differences that are based on age, gender, language and the different business units were found between the demographic groups. Structural equation modelling showed that job demands are associated with negative WHI and consequently with burnout, providing support for a full-mediation effect of negative WHI. Job resources were associated with negative WHI and consequently with burnout, providing support for partial mediation of negative WHI between job resources and burnout. Job resources were also associated with positive WHI and consequently with engagement, providing support for partial mediation of positive WHI between job resources and engagement. Recommendations for the organisation and future research were made. / Thesis (Ph.D. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2007.