Faculty of Engineering and Built Environment
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Browsing Faculty of Engineering and Built Environment by Type "Preprint"
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Item Application of a constrained non-linear hydraulic gradient design tool to water reticulation network upgrade.(Tayylor & Francis., 2006) Ilemobade, A.A.; Stephenson, D.Southern Africa has embarked on substantial expansion of its water supply network in order to ensure safe, reliable, convenient and sufficient water for everyone. To achieve this, new systems are being built and many existing systems are being upgraded. The upgrade of many existing systems is required for two reasons: some currently functional systems may run dry if subjected to additional demands as these systems were not initially designed to cater for such demand, and some systems are currently non- or sub-functional as they were ill-designed and/or ill-implemented from inception. Many of the systems that require upgrade are underdesigned due to a lack of skill, tools and/or knowledge of designers, or from other extraneous factors (e.g., illegal connections and sabotage). It is hardly surprising therefore that the failures of water projects in developing countries are recorded to be as high as 80%. Ill-designed systems increase operation and maintenance costs significantly. In especially Southern Africa, designers require simple, yet rigorously tested tools to facilitate sustainable, yet cost-effective network designs. Presented in this paper is a simple, yet robust constrained non-linear hydraulic gradient network reticulation design tool. The design tool is calibrated using the New York City water supply problem that has served as a benchmark problem for other models and then applied to the Selebi – Phikwe (SP) water reticulation network (WRN) in Botswana, which was designed based on engineering judgement. The optimization algorithm employed in the design tool is based on the concept that a hypothetical hydraulic gradient for a hydraulically balanced WRN exists that, when achieved iteratively, produces optimal pipe sizes and an optimal flow relation between each pipe. The unique problems and challenges of the SP WRN (pressure deficiencies in sections of the existing network and the proposed addition of three new residential developments) required determining the most appropriate peak and night flow operating scenarios, and optimal pipe sizes for the proposed expansion of the network. Optimization by trial and error had been previously employed in the design of the SP WRN—a common practice amongst water system designers, and the results are compared with those generated with the design tool. The design tool achieved a 62% reduction in total pipe cost from that obtained by trial and error for the SP WRN problem. At the same time, the design tool gives comparable pipe costs to those published in literature for the New York City water supply tunnels problem.Item Book review: The Architecture of Demas Nwoko, by John Godwin and Gillian Hopwood(Farafina, Lagos, 2007) le Roux, HannahGiven the challenges of access and archives, it is hard to get down to detail in the documentation of modern African architecture. This architectural monograph by Nigerian based architects John Godwin and Gillian Hopwood is a moving and meticulous catalogue of the designed work of their friend, the artist Demas Nwoko, that is refreshingly full of both architectural and anecdotal details. It begins with two short essays on Nwoko’s creative background and an analysis of his approach to design, but for the most part describes, in drawings, text and photographs, his twelve built and five unexecuted works.Item An extension to classical lamination theory for use with functionally graded plates.(Elsevier, 2011-01) Reid, R.G.; Paskaramoorthy, R.An extension to classical lamination theory is presented for the improved analysis of thin to moderately thick functionally graded plates. The method results in an explicit formulation that accommodates any through-thickness variation in the elastic, hygrothermal and piezoelectric properties of each layer. Additionally, variations in the material rotation angle, temperature, moisture content and electric field strength through each layer are taken into account. The method relies on representing with polynomial series the variation in both the properties of each ply and the hygrothermal and piezoelectric loading. Validation problems are presented that demonstrate the application and accuracy of the method.Item The response of layered anisotropic tubes to centrifugal loading.(Elsevier, 2016-04) Carpenter, H.W.; Reid, R.G.The displacement-based elastic solution for layered anisotropic tubes is extended to allow for the presence of centrifugal loading. The additional terms in the stress-strain equations derived in this work are validated by comparing the results obtained using the current solution against those determined using finite element simulation of rotating thin and thick-walled glass fibre reinforced plastic tubes of arbitrary anisotropic lay-up. The solution is presented in such a form that it can be utilised to determine the linear thermo-mechanical behaviour of rotating tubes with anisotropic lay-up, subjected to any combination of internal and external axisymmetric pressure, axial loading, torsional loading, and constant temperature change.