Bradford Scholars

Bradford Scholars is the University of Bradford online research archive. Access is free to anyone interested in research being conducted at Bradford. In the repository you will find a range of materials from journal articles and conference papers to research reports and theses.

Contact the repository team via openaccess@bradford.ac.uk with any queries about Open Access or how to deposit your research papers.

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  • PublicationOpen Access
    Turbulence Modelling of Tidal Currents in Rectangular Harbours
    Hakimzadeh, Habib; Falconer, Roger A.
    In this study turbulence refinements have been made to existing computational models for the prediction of currents and water levels in coastal and estuarine waters via the numerical solution of the depth- and layer-integrated Reynolds equations. As most flows in practice are always turbulent, it is necessary to try and model the turbulence as accurately as possible. Various turbulence models including the mixing length, k-s and algebraic stress turbulence models all adopting a time average statistical approach, and the Smagorinsky model of the Large Eddy Simulation type were considered in a 2-D model. Likewise, the two-layer mixing length and the k-s turbulence models were included in a 3-D model to calculate the vertical Reynolds stresses. As for the hydrodynamic equations, the finite difference method has been used for the discrete equations of the turbulence parameters. Likewise, the Alternating Direction Implicit scheme has again been used for solving the discretized turbulence equations. In the hydrodynamic equations the advective acceleration terms have been treated using the third-order upwind scheme, whereas the counterpart terms in the turbulence equations have been treated using the exquisite scheme. In the finite difference representation various closed boundary conditions, including the no-slip, semi-slip and partial-slip, have been considered for the turbulence diffusion terms in the hydrodynamic equations and in using zero-equation turbulence models. These closed boundary conditions have been found to lead to a significant difference in the predicted flow patterns, both in the 2-D and 3-D models. However, in using more sophisticated turbulence models only the common no-slip closed boundary condition has been used for the turbulence diffusion terms as well as the turbulence parameters. The modified 2-D model has been applied to the predictions of tidal flow in rectangular harbours with large and small aspect ratios, as well as to a practical case study (i.e. Rattray Island), whereas the refined 3-D model has been applied to the predictions of steady state flow in a channel, wind-induced currents in a channel, tidal flow in rectangular harbours and steady flow in a practical case study (i.e. Blithfield Reservoir). The predicted numerical model results have been compared with the measured laboratory and field data and an encouraging degree of similarity has been obtained for all of the case studies. In particular, the partial-slip condition, incorporated with the zero-equation turbulence model, gave close agreement with the experimental data. More sophisticated turbulence models were found to give closer agreement with the experimental data.
  • PublicationOpen Access
    Numerical Modelling of Geomorphological Processes in Estuarine Waters
    Kolahdoozan, Morteza; Falconer, Roger A.
    Numerical modelling of geomorphological processes in rivers, estuaries, harbours and coastal waters is an efficient means of predicting bed level changes for further use in planning the maintenance and management of these areas. Nowadays, quasi-3D models are increasingly popular, particularly with the rapid progress in the power of modem day computers. In this thesis the development and application of two-dimensional and three-dimensional numerical models for predicting geomorphological processes in estuarine waters have been under consideration, with particular emphasis on the unsteady initiation of motion criteria for sediment particles. The governing hydrodynamic, sediment transport and bed level change equations are reviewed in their differential form by using the conservation laws of mass and momentum for fluid and sediment particles. Then the depth integrated and layer integrated form of these equations are derived for the domain. Different solution procedures for developing the geomorphological model are discussed in this thesis according to the nature of flow for different computational domains. A new unsteady criteria for the initiation of motion has been proposed based on the mathematical analysis of the physical processes. In this hypothesis, it is assumed that tides can be approximated by a sinusoidal wave and by applying Newton's second law then the resulting time varying forces acting on sediment particle can be calculated. The proposed criteria for the initiation of motion have been included in the geomorphological models, namely GEO-DIV AST and GEO-TRIV AST, which have been developed for two-dimensional and three-dimensional geomorphological simulations based on depth integrated and layer integrated algorithms respectively. A series of experimental tests have been undertaken in a laboratory rectangular harbour to verify the geomorphological model. The measured bed level changes for the various values of related parameters are presented for the verification and validation of numerical models and proposed criteria. The numerical models have been run for several case studies including: (1) migration in a trench, (2) bed level changes in a partially closed channel, (3) geomorphological development in the laboratory rectangular harbour, and (4) geomorphological developments in the Humber Estuary due to tidal currents. Predicted velocity, sediment concentration distributions and bed level changes have been illustrated to show the geomorphological developments in the corresponding computational domain. The predicted velocity, sediment transport and bed level changes have been compared with measured laboratory and field data and also numerical results of reported models in the literature, with an encouraging degree of similarity being observed for all cases, confirming the validation of the proposed new criteria for the initiation of motion and the GEO-TRIV AST numerical model for successful three dimensional estuarine flow simulations.
  • PublicationOpen Access
    Blockchain Technology for Data Sharing in the Banking Sector
    (2020) Norvill, Robert E.; Awan, Irfan
    Know Your Customer compliance costs have never been higher for banks in Europe. This thesis looks at the application of blockchain technology to reduce Know Your Customer compliance costs. The work within aims to utilise the strengths of blockchain technology in order to reduce the costs of compliance for banks. This is done through collaboration with industry partners, resulting in a system designed to meet banks’ needs. The contributions of this work are: 1) A system which enables data sharing between banks, enabling 2) reduc tion of costs by at least 45%, and 3) reducing or eliminating over reliance on third parties, 4) an exploration of how to price data within the system is made in order to help banks further reduce their costs, 5) reduction of chain size by reducing the size of contract creation transactions in Ethereum by 90% for standard users, lastly, 6) to better understand the functionality and purpose of smart contracts. The system is the first of its kind to remove the requirement of third party storage solutions, and is the first to explore pricing aspects in detail.
  • PublicationOpen Access
    A Behavioural Compliance Framework for Effective Cybersecurity Governance and Practice
    (2020) Onumo, Aristotle O.; Awan, Irfan; Cullen, Andrea J.
    Although behavioural security constructs have received extensive scholarly attention, the unpredictability of human behaviour has continued to add to the complexity of deploying effective countermeasures. Cross-cultural behavioural approach aimed at improving security compliance and practice have equally remained under-researched, a gap in literature this thesis addresses. This thesis argues that in order to establish a sound and efficient organisational security practice, it is necessary to integrate the various interdisciplinary component in a socio-cultural context. The goal of the thesis, therefore, is to examine the role of culture in cybersecurity development and organisational security practice. The study first used a group comparism approach, classification and examination of archival data from International Telecommunication Union (ITU), International Organisation of Standards (ISO), and Hofstede cultural score and further deployed structural equation modelling (SEM) to analyse data from a case study of 122 employees from three public sector information technology organisation in Nigeria. Drawing evidence from the case studies, an emergent conceptual model was developed from the traditional human behaviour and organisational security practice. The model contribute to information security management by by identifying organisational triggers related to cultural and cognitive dynamics in information security practice. The model was developed by combining three theoretical frameworks. The out- come of the case studies demonstrates that accountability to specific security practice is a product of integrated management of employee cognitive and cultural dynamics and by dimensionalising organisational culture, the individual capacity to respond to emerging security threats also evolved, while targeted security programs to enhance the efficiency of organisational security practice is achieved. This research, by exposing the underlying institutional drivers and ideational dynamics on individual security behaviour contribute to theory building of behavioural security research within organisational context. The research reports on the theory of integration as a demonstration of explanatory flexibility not normally associated with behaviour security models thereby providing a sound theoretical and ideational support for incorporating different theoretical frameworks into a single model. This is an original endeavour and s such makes a number of contribution to the scholarship. The findings in this research have implications for policymakers and practitioners by elevating the importance of cultural and cognitive dynamics by enhancing operational clarity in organisational security practice and presenting opportunity to develop a creative and robust solution to the challenge of organisational security in line with cultural peculiarities.
  • PublicationOpen Access
    Capacity Enhancement Approaches for Long Term Evolution networks: Capacity Enhancement-Inspired Self-Organized Networking to Enhance Capacity and Fairness of Traffic in Long Term Evolution Networks by Utilising Dynamic Mobile Base-Stations
    (University of Bradford) Alrowili, Mohammed F.H.; Awan, Irfan; Holton, Robert
    The long-term evolution (LTE) network has been proposed to provide better network capacity than the earlier 3G network. Driven by the market, the conventional LTE (3G) network standard could not achieve the expectations of the international mobile telecommunications advanced (IMT-Advanced) standard. To satisfy this gap, the LTE-Advanced was introduced with additional network functionalities to meet up with the IMT-Advanced Standard. In addition, due to the need to minimize operational expenditure (OPEX) and reduce human interventions, the wireless cellular networks are required to be self-aware, self-reconfigurable, self-adaptive and smart. An example of such network involves transceiver base stations (BTSs) within a self-organizing network (SON). Besides these great breakthroughs, the conventional LTE and LTE-Advanced networks have not been designed with the intelligence of scalable capacity output especially in sudden demographic changes, namely during events of football, malls, worship centres or during religious and cultural festivals. Since most of these events cannot be predicted, modern cellular networks must be scalable in terms of capacity and coverage in such unpredictable demographic surge. Thus, the use of dynamic BTSs is proposed to be used in modern and future cellular networks for crowd and demographic change managements. Dynamic BTSs are complements of the capability of SONs to search, determine and deploy less crowded/idle BTSs to densely crowded cells for scalable capacity management. The mobile BTSs will discover areas of dark coverages and fill-up the gap in terms of providing cellular services. The proposed network relieves the LTE network from overloading thus reducing packet loss, delay and improves fair load sharing. In order to trail the best (least) path, a bio-inspired optimization algorithm based on swarm-particle optimization is proposed over the dynamic BTS network. It uses the ant-colony optimization algorithm (ACOA) to find the least path. A comparison between an optimized path and the un-optimized path showed huge gain in terms of delay, fair load sharing and the percentage of packet loss.
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