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The Faculty of Engineering at Stellenbosch University is one of South Africa's major producers of top quality engineers. Established in 1944, it currently has five Engineering Departments.
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- Item3D-feature recogntion from measured data(Department of Industrial Engineering, Stellenbosch University, 1999) Janssens, M.; Van Wijck, W.; Du Preez, N. D.ENGLISH ABSTRACT: This paper presents a method to automatically extract analytical entities like planes, spheres and cylinders from a file containing a cloud of points. The method facilitates the manipulation and reduction of large data sets and the evaluation of it. It can be used as a design tool, a quality control tool, data-processing tool or a data reduction tool. From a database of points, the user can automatically extract a subset of points belonging to an analytical entity of interest, within a predefined but adjustable level of confidence. If necessary, the dimensional parameters of the entity can also be calculated. The method is based on the subtle statistical properties of the least-squares technique that makes it compliant with the strict regulations in the co-ordinate measuring arena. Its robustness guarantees the applicability to less accurate environments than precision engineering.
- ItemA concentrating solar power value proposition for South Africa(Energy Research Centre, University of Cape Town, 2013) Gauche, Paul; Von Backstrom, Theodore W.; Brent, Alan C.Concentrating solar power (CSP) offers the potential for a high degree of localization and an alternative strategy to meet electricity demand for South Africa in a future of uncertain conventional resources. The integrated resource plan (IRP) makes strides to introduce renewables to the electricity generation system by 2030, but we argue that the proposed energy mix is too reliant on resources that are not only unsustainable but also at risk in the short to medium term. Coal and other conventional resources may be more limited than originally anticipated, which if true, requires action to be taken soon. CSP is currently the only sustainable and dispatchable energy technology that could domestically supply a significant portion of South Africa’s electricity needs. A balanced mix of PV, wind and CSP can provide the energy supply needed in South Africa, but steps are required soon to take advantage of the localization potential and excellent sustainable energy resources.
- ItemThe absence of a creative focus in the conventional engineering design process : identifying research opportunities to address this(SAIIE, 2016-05) Oosthuizen, Louzanne; Vlok, P. J.ENGLISH ABSTRACT: This paper synthesizes an overview of various models of the engineering design process with an overview of the most relevant theories within the field of creativity studies to conclude that (i) creativity plays a role throughout the engineering design process, and it is possible to incorporate creativity into the engineering design process in a systematic manner; (ii) doing so, at the very least, holds significant potential for economic benefit; and (iii) due to the complex interplay between creativity and the wide range of factors that influence it, organisational climates and management practices cannot simply be assumed to support creativity effectively. It is proposed that organisations be managed proactively to support creativity in engineering design. For this study, a structured literature search protocol was implemented to determine whether there is any evidence in the literature that engineering organisations are being managed proactively with this in mind; none was found. Two opportunities for future research are suggested based on these findings: (i) the development of a framework to guide the proactive management of engineering organisations to support creativity; and (ii) the development of mechanisms for measuring creativity in engineering organisations and engineering design.
- ItemAccounting for moment-rotation behaviour of connections in portal frames(South African Institution of Civil Engineering, 2014-04) Albertyn, Heindrich L.; Haas, T. N.; Dunaiski, Peter E.Portal frames are steel structures used to construct industrial buildings. Conventional analysis techniques used by practising engineering professionals assume that the eave, ridge and base connections are either infinitely rigid or perfectly pinned. This approach leads to less accurate analysis of the displacement behaviour of portal frames when subjected to external loading. Portal frames must therefore be analysed with rotational springs at all connections to yield accurate displacement behaviour. This investigation focused on determining the accuracy and economic feasibility of modelling portal frame connections with rotational springs. The rotational spring stiffnesses of all connections were required before the portal frame could be analysed in a second-order two-dimensional non-linear analysis. The rotational spring stiffnesses unique to each connection were determined from the moment-rotation behaviour obtained from a series of finite element analysis simulations of each connection. Thereafter these stiffnesses were used to determine the vertical and horizontal displacements of the portal frame. These displacements were compared with experimental test results. The reasons for the discrepancies between the numerical and experimental results were investigated through a sensitivity analysis. The findings suggest that it is not computationally feasible to analyse portal frames with rotational springs, even though the model’s predicted results are more accurate than those of conventional analysis using rigid and pin connections.
- ItemAdapting modern portfolio theory for prioritising asset care planning in industry(Southern African Institute for Industrial Engineering, 2014-05) Van den Honert, Andrew Francis; Vlok, Pieter-JanProductivity improvement within any organisation can lead to increased turnover. This study focuses on developing a maintenance productivity improvement model that is based upon an established financial investment portfolio technique known as the Modern Portfolio Theory (MPT). The model can be used as a tool to minimise and diversify the long term risk associated with variances or fluctuations in the increase in productivity in multiple maintenance service centres. This is achieved by optimising the most efficient way of splitting resources, such as time and money, between these multiple service centres, resulting in increased productivity and a more constant maintenance work load. This model is verified through the use of an efficient frontier, resulting in a graphical method to determine the link between the expected increase in productivity and the standard deviation of the increase in productivity. Ultimately this model can be adapted for use in many sectors within an organisation, over and above the application in maintenance prioritisation. This study concludes that the model offers a simple tool to aid decision-making among various combinations of assets within a maintenance context; and this model, adapted from MPT, was successfully validated with the use of an efficient frontier.
- ItemAdditive manufacturing for sustainable custom-designed implants(Southern African Institute for Industrial Engineering, 2019) Booysen, G. J.; Van der Merwe, A. F.; De Beer, D. J.ENGLISH ABSTRACT: Additive manufacturing (AM) has proven to be an attractive alternative manufacturing process compared with subtractive manufacturing (SM). Additive manufacturing has many advantages, such as mass customisation, less material wastage, and others listed in this article. However, the additive manufacturing of certified implants does not have the same degree of documentation and standardisation as the subtractive manufacturing process. As part of this research project, the problem statement is: “In offering additive manufacturing as an implant manufacturing solution, the complete process (design, manufacturing, and post-processing) had to be investigated in order to develop a certified manufacturing solution”.
- ItemAfrikaans and Dutch as closely-related languages : a comparison to West Germanic languages and Dutch dialects(University of Stellenbosch, Department of General Linguistics, 2015) Heeringa, Wilbert; De Wet, Febe; Van Huyssteen, Gerhard B.Following Den Besten’s (2009) desiderata for historical linguistics of Afrikaans, this article aims to contribute some modern evidence to the debate regarding the founding dialects of Afrikaans. From an applied perspective (i.e. human language technology), we aim to determine which West Germanic language(s) and/or dialect(s) would be best suited for the purposes of recycling speech resources for the benefit of developing speech technologies for Afrikaans. Being recognised as a West Germanic language, Afrikaans is first compared to Standard Dutch, Standard Frisian and Standard German. Pronunciation distances are measured by means of Levenshtein distances. Afrikaans is found to be closest to Standard Dutch. Secondly, Afrikaans is compared to 361 Dutch dialectal varieties in the Netherlands and North-Belgium, using material from the Reeks Nederlandse Dialectatlassen, a series of dialect atlases compiled by Blancquaert and Pée in the period 1925-1982 which cover the Dutch dialect area. Afrikaans is found to be closest to the South-Holland dialectal variety of Zoetermeer; this largely agrees with the findings of Kloeke (1950). No speech resources are available for Zoetermeer, but such resources are available for Standard Dutch. Although the dialect of Zoetermeer is significantly closer to Afrikaans than Standard Dutch is, Standard Dutch speech resources might be a good substitute.
- ItemAgility : a competitive weapon for South African manufacturers(SAIIE, 1998) Fourie, Cornelius J.; Schoeman, DanielENGLISH ABSTRACT: Agility enables a manufacturing enterprise to manage change as part of its routine business. By aligning the whole company to a single strategic vision and goal, together with internal and external initiatives, and the application of technology, such an enterprise will be able to deliver on the key competitive priorities of cost, quality, dependability and flexibility.
- ItemAn algorithm for fast optimal Latin hypercube design of experiments(Wiley-Blackwell, 2010-04) Viana, Felipe A. C.; Venter, Gerhard; Balabanov, VladimirThis paper presents the translational propagation algorithm, a new method for obtaining optimal or near optimal Latin hypercube designs (LHDs) without using formal optimization. The procedure requires minimal computational effort with results virtually provided in real time. The algorithm exploits patterns of point locations for optimal LHDs based on the ɸp criterion (a variation of the maximum distance criterion). Small building blocks, consisting of one or more points each, are used to recreate these patterns by simple translation in the hyperspace. Monte Carlo simulations were used to evaluate the performance of the new algorithm for different design configurations where both the dimensionality and the point density were studied. The proposed algorithm was also compared against three formal optimization approaches (namely random search, genetic algorithm, and enhanced stochastic evolutionary algorithm). It was found that (i) the distribution of the ɸp values tends to lower values as the dimensionality is increased and (ii) the proposed translational propagation algorithm represents a computationally attractive strategy to obtain near optimum LHDs up to medium dimensions.
- ItemAlignment of internal and external business and innovation domains(SAIIE, 2016-05) Katz, Bernard R.; Du Preez, Niek D.; Louw, LouisENGLISH ABSTRACT: “Instead of being really good at doing some particular thing, companies must be really good at learning how to do new things”. This ability to do new things involves both the identification and the mastery of the next ‘new thing’ as well as the ability to align the rest of the company with this new direction. This paper focuses on the alignment of innovation activities with the overall business strategy and infrastructure. An innovation strategic alignment model is presented that supports alignment in a company by identifying the driver of change and its impact on other areas of the business.
- ItemAlternative wall‑to‑slab connection systems in reinforced concrete structures(South African Institution of Civil Engineering, 2017-09) Gerber, Johann; Van Zijl, GideonENGLISH ABSTRACT: In many reinforced concrete structures the walls precede the construction of the connecting floors. A system is, therefore, required to connect the floors to the already cast walls. There are many different floor-to-wall connection systems available in South Africa, but their behaviour and capacity are not always fully understood, especially when the moment capacity of the joint is to be utilised. This study focuses on four systems: continuous starter-bars, pre-bent site-installed starter-bars, preassembled starter-bars and cast-in anchors with mechanical couplers. The design procedure for the continuous starter-bar system is well understood and documented in design codes, but not enough information is available on the design procedure for the other systems. Certain practical aspects of the installation process are also not fully understood. Cold-bending and straightening of the starterbars are inevitable in both bend-out systems. Previous research shows that this cold-working of the reinforcement can reduce the yield stress and E-modulus of the steel. In order to investigate these findings, a series of tensile tests are conducted. The results indicate that a significant reduction can be expected in both the yield stress and modulus of elasticity of the steel. Low-cycle fatigue tests further suggest that cold-bent steel also has a reduced ductility. The tensile tests are followed by the construction and testing of the systems in full-scale wall-to-slab connections. The effect of the coldbending on the starter-bars is clearly visible, as both the responses of the bend-out systems are less satisfying than the results from the continuous starter-bar system. The experimental phase is followed by numerical analysis of the connection systems. The finite element analyses show that the structural performance is significantly more sensitive to a reduction in the yield stress of the starter-bars, than to the use of a lower concrete grade. It is concluded that all the alternative connection systems can be implemented successfully in a moment-fixed wall-to-slab connection, but that the site-installed bendout system is the preferred method. However, in order to ensure that the system performs on the same level as conventional systems, it is recommended that the design should be conducted with a set of modified steel properties to allow for the negative effect of the cold-working on the starter-bars.
- ItemAnalysis of template-based detection algorithms for inshore Bryde’s whale short pulse calls(Institute of Electrical and Electronics Engineers, 2020) Ogundile, Olayinka O.; Versfeld, Daniel J. J.Marine mammals use sound for communication and echolocation within their ecosystems. The detection of these sounds is an important aspect of signal processing, such that we can estimate the spatial position and direction of arrival of these mammals, and have an understanding of their ecology. Passive acoustic monitoring (PAM) is widely used to understand marine mammal movement and vocal repertoire. In PAM, datasets are accumulated over days, months or years. Thus, it is impracticable to manually analyse the datasets because it is very large. This motivated the development of automated sound detection techniques for marine mammals, which most often varies depending on the vocal duration, frequency range and call type. In this paper, continuous recordings of Bryde’s whale ( Balaenoptera edeni edeni ) short pulse calls (< 3.1s long) were collected on a weekly basis from December 2018 to April 2019 on sighting of the individual in a single site in the endmost South-West of South Africa. The sound, previously not documented off South Africa, was observed on visual confirmation of the presence of inshore Brydes’s whale. In addition, the paper develops and analyses two automated template-based detection algorithms for this short pulse call, employing dynamic time warping (DTW) and linear predictive coding (LPC) techniques. These proposed template-based detectors are novel, as they have not being previously used in Bryde’s whale sound detection in the literature. When applied to the continuous recordings of the short pulse calls, the DTW-based and LPC-based detection algorithms obtained a sensitivity of 96.04% and 97.14% respectively for high signal-to-noise ratio (about 10dB above the ambient sound). Otherwise, for low SNR, the DTW-based and LPC-based detection algorithms obtained a sensitivity of 94.98% and 96.00% respectively. These detection algorithms exhibit low computational time complexity and can be modified to analyse the movement of obscure but vocal marine species instead of manual identification.
- ItemAn analysis of the extent to which industry 4.0 has been considered in sustainability or socio-technical transitions(Southern African Institute for Industrial Engineering, 2019) Asiimwe, Martha Mukama; De Kock, Imke H.ENGLISH ABSTRACT: A growing database of literature is geared towards the analysis and evaluation of Industry 4.0. One of the points of interest is the assessment of Industry 4.0 in the context of sustainability and sustainable development. However, there seems to be a gap in the literature focusing on transitions to more sustainable states that are evidently fostered by socio-technical [system] transitions, sometimes referred to as ‘sustainability transitions’. This presents the need to evaluate the interfacial layers of these disciplines, given the larger challenge of sustainability and Industry 4.0’s potential to support complex problem-solving. This paper presents a bibliometric analysis of the literature that jointly considers the concepts of sustainability, sustainable development, and socio-technical systems, and the transitions thereof with Industry 4.0.
- ItemAnalysis of the use of space and module-configured packaging to improve fruit export mass in a refrigerated container(Southern African Institute for Industrial Engineering, 2019) Louw, L.; Nel, S.ENGLISH ABSTRACT: The South African fruit export industry is a key contributor to thecountry’s economy, and must be managed efficiently to that ensure its vital role is maintained. Significant increases in reefer freight rates have placed substantial pressure on the fruit export industry to find new and innovative ways of improving the space / volume use of fruit in these reefer containers. Improvements must adhere to key constraints to ensure that fruit quality and shelf life are not compromised. This paper analyses the current potential for increasing the mass of stone and pome fruit that is exported in reefer containers. The study indicates that pome fruit has the greatest opportunity for improvement, whereas stone fruit has less room for improving the use of space / volume. Proposed improvement methods are: optimal packing arrangements of fruit; improved packaging and pallet dimensions (special pallet sizes); improved stacking arrangements of cartons on pallets and pallets in reefers; and lastly, the use of slip sheets instead of pallets.
- ItemAnalysis of water use by gated communities in South Africa(South African Water Research Commission, 2018) Du Plessis, Jacques J. L.; Jacobs, Heinz E.ENGLISH ABSTRACT: Gated communities (hereafter GCs) are popular in many countries, including South Africa, because added security and lifestyle improvements are offered relative to homes built on freestanding properties. One of the key factors for the popularity of GCs is the availability of amenities to support the demands of the residents, such as gymnasia, walkways, golf courses, play parks and polo fields. Further benefits include the improved management of infrastructure such as telecommunication services, roads, water, sewer, electrical and stormwater assets. GCs are often governed by trustees or homeowners’ associations, responsible for the operation and the maintenance functions of the infrastructure, as well as implementing and adhering to legislation that pertains to the GC. As part of this study, the monthly water-use records of 2 888 GCs in 3 different South African cities were analysed. Water use was evaluated for each GC as a whole, and also per household in each case. The average number of homes per GC was 33 households/GC, with the smallest GC in the study sample containing 3 houses and the largest 524 houses. One of the study sites was in the winter rainfall region, while 2 sites were in the summer rainfall region. The average annual water use of individual households in each GC was plotted against current guidelines and was found to be relatively low. The average annual daily demands of all properties in the winter rainfall region was 0.63 kL/d, compared to 0.66 kL/d and 0.49 kL/d for the two study sites in the summer rainfall region. The results highlighted peculiarities in the water use of GCs that have not been reported on before, in particular the relatively low water use and the differences between GC homes’ water use in the various rainfall regions.
- ItemAnalytical modeling of surface-mounted and consequent-pole linear vernier hybrid machines(Institute of Electrical and Electronics Engineers, 2021) Botha, Christoff D.; Kamper, Maarten J.; Wang, Rong-Jie; Chama, AbdoulkadriENGLISH ABSTRACT: This paper presents an analytical method for modeling the no-load air gap ux density of a surface-mounted and a consequent-pole linear Vernier hybrid machine (LVHM). The approach is based on simple magneto-motive force (MMF) and permeance functions to account for the doubly-slotted air gap of the LVHM. These models are used to determine the ux linkage, induced electromotive force (EMF) and average thrust force of each machine. The accuracy of the two analytical models is validated by comparison with 2D nite element method (FEM) solutions. Based on the analytical models, it is found that the working harmonics of both surface-mounted and consequent-pole LVHMs are essentially the same. However, the magnitudes of these working harmonics in the consequent-pole LVHM are invariably greater than those of surface-mounted LVHM. Further, using the analytical model, the contribution to the thrust force of the machine by each individual working harmonic can be shown clearly, and is used to explain why the consequent-pole LVHM has improved performance despite using only 50% of the permanent magnet (PM) material compared to the surface-mounted LVHM.
- ItemAnimal-borne behaviour classification for sheep (Dohne Merino) and rhinoceros (Ceratotherium simum and diceros bicornis)(BioMed Central, 2017-11-21) Le Roux, Solomon Petrus; Marias, Jacques; Wolhuter, Riaan; Niesler, ThomasBackground: The ability to study animal behaviour is important in many fields of science, including biology, behavioural ecology and conservation. Behavioural information is usually obtained by attaching an electronic tag to the animal and later retrieving it to download the measured data. We present an animal-borne behaviour classification system, which captures and automatically classifies three-dimensional accelerometer data in real time. All computations occur on specially designed biotelemetry tags while attached to the animal. This allows the probable behaviour to be transmitted continuously, thereby providing an enhanced level of detail and immediacy. Results: The performance of the animal-borne automatic behaviour classification system is presented for sheep and rhinoceros. For sheep, a classification accuracy of 82.40% is achieved among five behavioural classes (standing, walking, grazing, running and lying down). For rhinoceros, an accuracy of 96.10% is achieved among three behavioural classes (standing, walking and lying down). The estimated behaviour was established approximately every 5.3 s for sheep and 6.5 s for rhinoceros. Conclusions: We demonstrate that accurate on-animal real-time behaviour classification is possible by successful design, implementation and deployed on sheep and rhinoceros. Since the bandwidth required to transmit the behaviour class is lower than that which would be required to transmit the accelerometer measurements themselves, this system is better suited to low-power and error-prone data communication channels that may be expected in the animals habitat.
- ItemThe applicability of nanofiltration for the treatment and reuse of textile reactive dye effluent(Water Research Commission, 2015) Chollom, M. N.; Rathilal, S.; Pillay, V. L.; Alfa, DorcasThe main aim of the study was to test the feasibility of using nanofiltration (NF) processes for the treatment of reactive dyebath effluents from the textile industry, in order to recover the water and chemicals (salts) for reuse purposes. The study of the reusability of nanofiltered water for dyeing has been given little or no attention. About 30% of reactive dyes remain unfixed on fibres; the unfixed dyes are responsible for the colouration in effluents. Membrane processes were employed to treat reactive dye-bath effluents to recover the salts and water. Investigations were conducted firstly with ultrafiltration (UF) used as a pretreatment for NF. Secondly, evaluations were performed for 2 types of NF membranes (SR90 and NF90), in terms of quality of permeate produced and fluxes achieved for 2 different samples of effluent. The effect of cleaning on membrane performance was assessed. A reusability test was carried out on both permeate samples for dyeing light and dark shade recipes. The use of UF as pre-treatment to NF resulted in rejection of colloidal substances > 90% and a 15% flux improvement. Permeate from NF90 had a conductivity of 76 µS/cm and total organic carbon (TOC) of 20 mg/ℓ, as compared to SR90 which had a conductivity of 8.3 mS/cm and a TOC of 58 mg/ℓ. Light shade from NF90 gave satisfactory results on dyeing, with no colour difference. However a variation in colour was noticed when the medium sample was used to dye the light shade. Both NF permeates gave satisfactory results when used to dye the dark shades. Permeate from NF90 was within the accepted range for reuse, while permeate from SR90 had a higher salt recovery. Chemical cleaning resulted in 80% flux recovery. From the reusability test it was concluded that permeate from NF90 met the reuse criteria for feed water to the dye bath.
- ItemThe applicability of the centeno, chaudhary and lopez repair time standard methodology in a rail maintenance environment(SAIIE, 2015) Rommelspacher, Karl Otto; Fourie, Neels; Mutibura, AbelThe establishment of labour standards within a production environment has become common practice, and is receiving growing recognition in the maintenance environment. However, the application of labour standards in a transit maintenance organisation has received limited attention. Centeno, Chaudhary and Lopez have developed a repair time standard methodology that has been applied in the transit bus maintenance facilities of three agencies in central Florida in the USA. An investigation into the applicability of this methodology in a rail maintenance environment in South Africa forms the basis for this study.
- ItemThe application of activated carbon for the adsorption and elution of platinum group metals from dilute cyanide leach solutions(Southern African Institute of Mining and Metallurgy, 2013) Snyders, C. A.; Mpinga, C. N.; Bradshaw, S. M.; Akdogan, G.; Eksteen, J. J.ENGLISH ABSTRACT: The research presented in this paper investigated the practical aspects of the recovery of platinum group metals (PGMs) from a dilute cyanide leach solution containing base metals, in a manner similar to that used for gold extraction in a typical CIP process, and focuses on both the adsorption and elution stages. The carrierphase extraction of precious metals using activated carbon offers significant advantages over other processes in terms of simplicity, the high pre-concentration factor, rapid phase separation, and relatively low capital and operating costs. As a sorbent, activated carbon is still by far the most important material because of its large surface area, high adsorption capacity, porous structure, negligible environmental toxicity, low cost, and high purity standards. Adsorption tests were conducted on a pregnant alkaline leach solution (0.15 ppm Pt, 0.38 ppm Pd, 0.1 ppm Au) resulting from cyanide extraction performed in column leach tests. The initial adsorption rates of Pt, Pd, and Au were very fast and recoveries of these three metals were approximately 90 per cent after 2 hours, and 100 per cent for Pt, 97.4 per cent for Pd, and 99.9 per cent for Au after 72 hours. The parameters that influence the extraction of PGMs and Au were examined to assess their relative importance during the adsorption process in order to provide the basis for process optimization. The concentration of thiocyanate was not identified as significant factor for PGMs adsorption, while Ni concentration was the most significant extraction process parameter. Base metal cyanide complexes adsorb and compete with the PGM complexes for sites on activated carbon, and while copper adsorption can be minimized by adjusting the residence time, Ni adsorbs at approximately the same rate as the PGMs, influencing the loading capacity and adsorption kinetics of the PGMs. The feasibility of eluting platinum and palladium cyanide complexes from activated carbon using an analogue of the AARL process was investigated. Platinum and palladium elute from activated carbon almost to completion in 4 to 5 bed volumes at 80°C, while the elution of gold at this temperature is slow, with a significant amount of gold still to be eluted after 16 bed volumes. The equilibrium loading of gold is exothermic in nature (Fleming and Nicol, 1984) which will result in an increase in gold elution kinetics with an increase in temperature at similar pre-treatment conditions. A similar result was found for the elution of Pt and Pd. Cyanide pre-treatment was found to have a significant influence on PGM elution. Higher cyanide concentration in the pre-treatment step results in more efficient elution up to a point, and results suggest the possibility of an optimum cyanide concentration, beyond which elution efficiency starts decreasing due to increased ionic strength.