The influence of PFA particle size on the workability of cementitious pastes

In this dissertation the effects of different types of Pulverized Fuel Ash (PF A)-types on the workability of cementitious pastes containing relative large amounts of PF A were investigated. The different types of PF A were produced at the same source thus they were chemically similar but differed in terms of average particle size and size distribution (grading). By using a two-point measurement technique based on flow through a J-shaped tube it was possible to detect relative small differences in workability between pastes. It was found and concluded that the different types of PFA had a significant effect on the workability of pastes containing cement and PFA as well as PF A alone. The physical differences between the PF A-types were quantified and their effects on workability investigated. It was concluded that PF A with a broader particle size distribution range produced pastes with higher workability at constant water content. It was found that compressive strength as measured after 28 days were solely a function of the water/cementitious ratio for the curing regime employed. It was concluded that for curing conditions used the type of PF A used could have a significant effect on compressive strength when constant workability is required.Dissertation (MSc (Transportation))--University of Pretoria, 2006.Civil Engineeringunrestricte

A South African perspective of the requirements discipline : an industry review

Please read abstract in article.http://www.saiee.org.za/DirectoryDisplay/DirectoryCMSPages.aspx?name=Publications#id=1588&dirname=ARJ&dirid=337am201

Requirements practitioner behaviour in social context : a survey

The purpose of this research paper is to discover the social behaviour of practitioners that causes the communication breakdowns during the requirements engineering process. Requirements emerge from the social interaction and communication between the requirements practitioner and the various stakeholders. The main problems with the requirements engineering process are communication and coordination breakdowns, as well as the lack of domain knowledge or understanding of the problem. These challenges are all related to the social interaction during the requirements engineering process that impacts the quality of requirements. In practice, requirements are still produced with errors which then lead to unsuccessful solutions to problems. The ultimate goal of any practitioner is delivering a solution fit for purpose first time around. If the social patterns of practitioners that deliver quality requirements are known and compared with those that do not deliver quality requirements, individual performance can be adjusted. The results of this study confirmed that quality of requirements is dependent on the communication established between the requirements practitioner and relevant stakeholders. The communication is enabled through the trust relationships between the parties. A description of how practitioners behave during the requirements process is provided. By discovering these interaction patterns, communication can be improved and made more effective. Additionally, the relationships between the practitioners and their stakeholders are described. These trust patterns provide insight into the levels of collaboration, communication and sharing of knowledge between the practitioners and their stakeholders. By identifying these relationship patterns, the value each party receives from the relationships could increase, and the communication breakdowns could be minimised.http://www.saiee.org.za/displaycustomlink.aspx?name=AfricaResearchJournalam201

An integrated systems approach to risk management within a technology-driven industry, using the design structure matrix and fuzzy logic

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 methodologyRisiko-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, en word nie effektief geїnterpreteer deur middel van konvensionele beheermetodes nie. Alternatiewe stelselvoorstelling- en analiseringstegnieke kan gebruik word om die sisteeminteraksies te visualiseer. Die Ontwerp Struktuur Matriks (‘design structure matrix’), en Wasige Logika (‘Fuzzy Logic’) word ingespan om hierdie interaksies voor te stel en eenvoudig te kwantifiseer. ’n Sementaanleggevallestudie word gebruik om die risikobestuurmetodologie op die proef te stel.This article is an extended version of a paper presented at the 2011 ISEM conference.http://www.journals.co.za/ej/ejour_indeng.htmlai201

A system dynamics approach to technology interaction : from asymptotic to cyclic behaviour

This paper is an extension and elaboration of previous research on the simulation of three competing technologies that interact. A modified version of the three-technology system is investigated, and some initial system dynamics results are reported illustrating the progression from asymptotic to cyclic behaviour. Technology is considered in this research as a result of innovation, a rate-dependent process that may include several non-linearities due to interaction with the environment and social context. Using bibliometrics as a research data source is an interesting way to trace technology growth patterns very effectively. In this research, the existence of cyclic behaviour in two real life technologies is illustrated using bibliometrics. In this paper, a technology systemconsisting of three interacting technologies is treated andmodelled in a coupled manner where the interacting dynamics is described by the Lotka–Volterra system of differential equations. The effect of interaction between the technologies and the period of cyclic behaviour is illustrated parametrically. Furthermore, the possible uncertain diffusion as well as interaction effect for two of the technologies is also addressed in this research using a Monte Carlo multivariate simulation technique and a system dynamics approach. The research method is exploratory and case based.University of Pretoria, the University of Johannesburg and the National Research Foundation (NRF) in South Africa.http://www.journals.elsevier.com/technological-forecasting-and-social-change2016-08-31hb201