Whole Life Cost Modelling For Railway Drainage Systems Including Uncertainty

The UK railway drainage system is facing significant asset management challenges due to the presence of large numbers of assets with long asset life cycles. Maintaining the required asset performance economically and efficiently, while complying with the relevant legislation and regulations is a major concern for Network Rail's asset managers. The whole life cost (WLC) approach has been developed and implemented in many industries and has proven its usefulness in the management of assets, particularly for assets with long life spans and in situations of uncertain future expenditure. WLC involves estimating the present value of the total cost of ownership over any asset's likely operational life. It is often integrated with decision support tools to enable a more robust decision making process. This has significant benefits in regulated industries in which all expenditure requires clear justification. This project developed a whole life cost model suitable for railway drainage systems, considering the uniqueness and complexity of costs associated with railway business operations. This WLC model can offer prediction of the transitions of drainage assets condition grades; assessments of drainage system operational performance; and provide realistic estimates of financial requirements in order to achieve desired operational performance; and evaluate the financial consequences due to loss of performance. This WLC model provides the information to build decision support tools that can help Network Rail prioritise drainage maintenance and refurbishment based on available and anticipated budgets and operational risks. This work demonstrated that the whole life cost modelling approach can provide an ideal solution for sustainably maintaining drainage systems while optimising the total cost of ownership and minimising operational, social and environmental impacts. The developed WLC approach enables asset managers to make decisions both on a strategic and operational level. Strategically, WLC approaches can forecast the overall budget and workload needed to maintain an infrastructure system over its assets' lifetime or a predefined financial period. Tactically, it can provide the asset owner with an optimum renewal, maintenance and utilisation plan under a given risk/cost requirement. This project provides WLC approaches that operate at both a strategic and tactical level for the UK railway drainage system. The methods developed in this thesis are now being implemented by NR into operational practice

Fresnel diffraction patterns as accelerating beams

We demonstrate that beams originating from Fresnel diffraction patterns are self-accelerating in free space. In addition to accelerating and self-healing, they also exhibit parabolic deceleration property, which is in stark contrast to other accelerating beams. We find that the trajectory of Fresnel paraxial accelerating beams is similar to that of nonparaxial Weber beams. Decelerating and accelerating regions are separated by a critical propagation distance, at which no acceleration is present. During deceleration, the Fresnel diffraction beams undergo self-smoothing, in which oscillations of the diffracted waves gradually focus and smooth out at the critical distance

Pilot-scale spinning and sucrose-tetra-aldehydes-crosslinking of feather-derived protein fibers with improved mechanical properties and water resistance

Pliable and water-resistant protein fibers from feathers were developed via continuous one-step spinning and crosslinking using sucrose-tetra-aldehydes. Though flexible protein fibers from feathers were developed, poor wet stability and low tenacity still limit the large and high-end applications of feather-derived fibers. Despite that saccharide aldehydes are considered as an efficient and sustainable crosslinker, substantial concerns such as generation of formaldehyde, high consumption of modifiers, loss of mechanical properties, yellowing, and decline in dyeability of fibers, exist after crosslinking. In this work, we controlled structures of crosslinkers and incorporated disaccharide-tetra-aldehydes into a continuous wet-spinning line. No formaldehyde was generated in the whole process. Protein fibers with controlled aldimine crosslinkages had not only a 92% tenacity retention after immersed in water for 1 week but also a substantial increase in mechanical properties. The dry and wet tenacity of feather-derived fibers was 120% and 90% of wool, respectively. Moreover, crosslinking from disaccharide-tetra-aldehydes retained the color of fibers and minimized the consumption of amine groups, the dyeing sites, on keratin. No toxicity was introduced by crosslinking. This work promotes resource recovery from poultry wastes, decreases the reliance of fiber industry on petroleum-based products, and diminishes environmental impact of fiber industries

Optimal Caching Policy of Stochastic Updating Information in Delay Tolerant Networks

To increase the speed of information retrieval, one message may have multiple replicas in Delay Tolerant Networks (DTN). In this paper, we adopt a discrete time model and focus on the caching policy of stochastic updating information. In particular, the source creates new version in every time slot with certain probability. New version is usually more useful than the older one. We use a utility function to denote the availability of different versions. To constrain the number of replicas, we propose a probabilistic management policy and nodes to discard information with certain probability determined by the version of the information. Our objective is to find the best value of the probability to maximize the total utility value. Because new version is created with certain probability, nodes other than the source may not know whether the information stored in them is the latest version. Therefore, they can make decisions only according to the local state and decisions based on the local state can be seen as local-policy. We also explore the global-policy, that is, nodes understand the real state. We prove that the optimal policies in both cases conform to the threshold form. Simulations based on both synthetic and real motion traces show the accuracy of our theoretical model. Surprisingly, numerical results show that local-policy is better than the global-policy in some cases