Saudi Cultural Missions Theses & Dissertations
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Item Restricted Influence of diphenyliodonium hexafluorophosphate salt (DPI) and ion-releasing glass fillers (45S5) on physical, mechanical and chemical properties of model resin composite formulations(University of Manchester, 2024-07-30) Alotaibi, Saad; Silikas, Nick; Watts, DavidRecurrent dental caries is a major reason for resin composite restoration replacement. 45S5 Ion-releasing glass (IRG) fillers are promising for functionalizing resin composites. They aid in hydroxyapatite deposition and remineralization of dental tissues. Diphenyl iodonium hexafluorophosphate (DPI) is a UV light initiator that replenishes Camphorquinone (CQ) by replacing inactive radicals with phenyl active radicals. The aim of this research was to explore the interactive effect of DPI and IRG on short and long-term material properties. Model resin-composites with varying amounts of IRG were prepared using a UDMA/TEGDMA resin system and either a unary or binary (includes DPI) photo-initiator system. Polymerization related properties such as degree of conversion (DC), shrinkage strain (SS) and depth of cure (DoC) were measured. IRG negatively impacted DC and DoC when higher content was used while DPI improved both DC and DoC. The SS was lower in the unary group and with higher IRG content confirming an inverse relation between DC and SS. Martens hardness (HM) and related parameters, indentation modulus (EIT) and creep (CIT), as well as the effect of storage in water or ethanol on these parameters were tested. HM and EIT decreased and CIT increased linearly as the amount of IRG is increased. Deterioration of HM and EIT through aging was more pronounced in specimens containing higher IRG amount. DPI showed higher HM, EIT and lower CIT only at higher IRG content compared to the unary group. Water sorption, solubility, hygroscopic dimensional changes and ions release were assessed. IRG significantly increased water sorption, solubility and hygroscopic expansion. Inclusion of DPI reduced water sorption, solubility and hygroscopic expansion. Release of calcium, sodium and phosphate were dose dependent on IRG. This study concluded that 45S5 IRG, while offering potential means of remineralisation, diminished the material’s overall properties. The inclusion of DPI enhanced the polymerization and overall properties of the tested model resin composites.10 0Item Restricted Moving Target Detection and Prediction towards Cyber Agile Cellular Networks(Alotaibi, Saad, 2019-04-29) Alotaibi, Saad; Song, HoubingAgile networks such as cellular networks are often prone to attacks emanating from various loopholes. The security loopholes increase the vulnerability of a network whereby the attackers are able to utilize the attack surface to execute an attack. One of the best approach of eliminating the security loopholes is to reduce the attack surface that in the network. An approach known as Moving Target Defense (MTD) is a robust mechanism aimed at reducing the attack surface in a cyber-agile network. This paper proposes the development of an MTD framework aimed at reducing the attack surface in a cloud- based network. The approach aims to formulate how multiple virtual machines can be migrated from one network layer to another with the aim of minimizing the chances of an attacker exploiting the network vulnerabilities. The proposed framework also addresses the mechanism of transforming the I.P addresses of the virtual machines after successful migration to the new network layer. The framework is simulated with the OpenStack platform whereby the network layer is implemented using nova- compute while the hardware is implemented using neuron framework. The algorithmic framework is further supported and implemented using Python programming platform. The experimental results indicate that the migration process is attained within a maximum duration of 0.3 seconds, which is adequate enough to prevent an attacker from executing an attack on the network. The proposed MTD framework is capable of improving the security of a cyber-agile network by minimizing the attack surface. For enhancing the security of the system, the IP mutation methodology has also been proposed along with MTD. For checking the efficiency of proposed IP mutation methodology, two metrics were defined i.e. assurance and avoidance. The results for IP mutation methodology suggested that it uses flexible and elastic characteristics of SDN and helps to enhance the security of the system.13 0Item Restricted Internet of Things Supply Chain Risks and Defences(Alotaibi, Saad, 2019-04-29) Alotaibi, Saad; Song, HoubingThe unprecedented emergence of network preinstalled devices which are designed to connect to the internet by default, promises convenience by recurrent and consistent advancement every day. It also has a promise of better security and efficient functionality. But even the lat- est gadget launched in the market to consumers comes with potential security flaws which later skilled hackers, who al- ways seem to a step ahead of executive security technicians, exploit these weak spots, infect the system with malicious malware and penetrate with ease in the private and wide area networks. These tech-savvy devices are collectively called internet of things or simply IOT. They are the tradition non-networking devices aside from personal computers, laptops, tablets, and smartphones. Some of them are in our house vicinity such, electric cars, kettles, LED light bulbs, electric kettles, Bluetooth speakers and many more. While others are in the industrial scale, such as the execution of tasks in robotic factory assembly and artificial intelligence used in war and commercial planes such as autopilot systems. Due to these rapid modifications and avid application IOT in the industrial sector, most early adopters of the technology have ways attempted to get the upper hand over their business rivals. There are various objectives while undertaking IOT projects at an industrial scale, but mainly advanced customer support and smooth ground operations and as a source of new Streams incomes top the priorities of the majorities of industrial giants and conglomerate corporations. IOT security cannot be discriminated rather be the major priority of the IOT system at every level, and must support the safety, data privacy, high standards of confidentiality and a reliable security system. There is a notable convergence of the operating system and the information technology sector which contends with a cultural clash, but always be accompanied by trustworthiness. The need to countermeasure these emerging challenges led to the Industrial Internet Consortium (IIC). It was founded in 2014 to make way for realizing the monetary value in IIOT and tackle the threats that face those that depend and live proximal to the IOT systems.18 0