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Modelling Thermal Degradation of Flame-Retarded Epoxy Resin Formulations under Different Heating Conditions
No full textThe thermal degradation kinetics of epoxy resin, triglycidyl-p-aminophenol (TGAP), and its flame-retarded formulations are investigated by thermogravimetric analysis (TGA) under oxidative conditions and are modelled using a simple global multi-step mechanistic scheme. Experimental TGA data acquired under non-isothermal conditions is used to optimise the kinetic parameters for selected boundary linear heating rates. These optimised kinetic parameters which adequately describe the thermal degradation process of epoxy resin formulations over the defined range of experimental conditions are then applied in the prediction of mass loss profiles of investigated materials under different heating conditions
Learning in fully recurrent neural networks by approaching tangent planes to constraint surfaces
No full textIn this paper we present a new variant of the online real time recurrent learning algorithm proposed by Williams and Zipser (1989). Whilst the original algorithm utilises gradient information to guide the search towards the minimum training error, it is very slow in most applications and often gets stuck in local minima of the search space. It is also sensitive to the choice of learning rate and requires careful tuning. The new variant adjusts weights by moving to the tangent planes to constraint surfaces. It is simple to implement and requires no parameters to be set manually. Experimental results show that this new algorithm gives significantly faster convergence whilst avoiding problems like local minima
Constructing safety on sites: an exploration of the social construction of safety on large UK construction sites
No full textSignificant attempts have been made by large contractors in the UK construction industry to improve safety on their sites. Safety management systems have been put in place, minimum training requirements have been established, and worker engagement initiatives implemented in the quest for a positive safety culture. However accidents and incidents still occur.Grounded in social constructionism, this study sought to explore how people construct safety in and through their interactions at work on the large construction sites of the UK. Data was collected from five UK construction projects, all over £20m in value, and included site safety signage, conversations discussing safety and various safety documents. Discourse analysis of the data revealed considerable variation in the contextual constructions of safety.Safety was found to be inconsistent, incomplete and incidental, relating to a variety of different realities in a variety of different contexts. Relatively straightforward constructs and discourses developed around safety, such as its polarisation, the construction of safety as PPE itself, and the development of safety as un-safety. However these were further developed by more complicated and interrelated discourses of safety as practice, enforcement and engagement. The variation within and between these master discourses has consequences for safety culture in terms of its construction, homogenisation and perpetuation on sites.The study makes recommendations for further academic research to examine the variation in the discourses of safety within the management hierarchy, who seek to develop a safe work environment through the safety culture programmes yet are challenged by the conflicts of safety as engagement and safety as enforcement. The study also suggests industry interventions to facilitate the improvement and development of practices to assist safety management on large UK construction sites
Reach North West; 10-year Evaluation Report
No full textAs Reache North West approaches its first decade it was felt that it was time to re-evaluate the programme and its journey. An external report was produced in 2006 and much has changed in the intervening period. It was felt that it was appropriate to use similar models of evaluation as the 2006 report, as it allows a comparable evaluation with regards to the contextual placement of Reache. The evaluation in this report differs from the 2006 report as it does not engage with the current membership body, but instead engages with those who have gone through the programme and have successfully gained employment, therefore being able to give a more informed review of Reache North West and its programme of study
Simultaneous reduction and surface functionalization of graphene oxide with POSS for reducing fire hazards in epoxy composites
No full textSimultaneous reduction and surface functionalization of graphene oxide (GO) was realized by simple refluxing of GO with octa-aminophenyl polyhedral oligomeric silsesquioxanes (OapPOSS) without the use of any reducing agents. The presence of OapPOSS made the hydrophilic GO hydrophobic, as evidenced by the good dispersion of the OapPOSS-reduced GO (OapPOSS-rGO) in tetrahydrofuran solvent. The structure of OapPOSS-rGO was confirmed by XPS, FTIR and TEM. A morphological study showed that, due to the good interfacial interaction between the functionalized graphene and epoxy, OapPOSS-rGO was dispersed well in the matrix. With the incorporation of 2.0 wt% of OapPOSS-rGO, the onset thermal degradation temperature of the epoxy composite was significantly increased by 43 °C. Moreover, the peak heat release rate, total heat release and CO production rate values of OapPOSS-rGO/EP were significantly reduced by 49%, 37% and 58%, respectively, compared to those of neat epoxy. This dramatically reduced fire hazards was mainly attributed to the synergestic effect of OapPOSS-rGO: the adsorption and barrier effect of reduced graphene oxide inhibited the heat and gas release and promoted the formation of graphitized carbons, while OapPOSS improved the thermal oxidative resistance of the char layer
Communication Strategy for Grid Control and Monitoring of Distributed Generators in Smart Grids using IEC and IEEE Standards
No full textDistributed generators (DGs) in Smart Grids should actively participate in the grid control of active power (P), reactive power (Q), frequency (f), and voltage (U) through their grid interfaces, namely inverters. As these DGs are joining the existing conventional power systems and for smooth transition towards Smart Grids, these DGs must follow the existing grid control, which is used by the UCTE. However, standard communication between utilities controllers and inverters is needed for the grid control and for the exchange of power. Therefore, a strategy is proposed depending on the UCTE grid control by clustering the secondary control using international communication standards. De facto, proprietary and standard protocols are investigated for this purpose. Then, logical nodes needed for primary and secondary grid control are adopted from the IEC 61850 that ensures interoperability. For communication, standard legacy SCADA protocols IEEE P1815 (DNP3) and IEC 60870-5-104 are proposed, which introduce standard communication mechanism
Shape memory effect and thermomechanical properties of shape memory polymer fabric composite in tension mode
No full textFibers and fabrics are often used to reinforce shape memory polymers (SMPs) to improve their mechanical strength and properties, and the composites have been widely used in engineering. However incorporation of fibers and fabrics in SMPs are often accompanied with the degradation of thermal mechanical properties and shape memory effect. The thermomechanical properties and degradation mechanisms of a shape-memory polymer composite (SMPC) were investigated. Up to 100% extension, the SMPCs showed good shape memory effect with excellent recovery ratio, recovery stress and mechanical properties; while beyond that the recovery ratio and stress of the composites deteriorate rapidly due to the significant delamination and debonding of fibers and fabrics from the SMP resin and accumulation of broken fibers
Developing Digital awareness: are we forgetting our staff?
No full textThis presentation intends to inform the challenges faced during the planning, development, implementations, and reviews of an e-Strategy in AME and AMT to facilitate digital support, collaboration, understanding and personal development to enhance the teaching and learning agendas in all three subject areas, and to update about the lessons learned and good practices attempting to close the gap in the 'academic digital divide' within the faculties
Defusing the risk of borrowing: The psychology of payment protection insurance decisions
No full textConsumers can defuse the financial risks of credit default by taking payment protection insurance (PPI). In two studies, predictions derived from Huber’s risk defusing operator theory of decision making were tested. We investigated the effects on PPI judgements and decisions of previous experience, cognitive appraisal, emotion and changes in PPI cost and level of cover. In Study 1, a randomized groups experiment, 241 high street bank customers were presented with scenarios in which they chose whether or not to purchase PPI. Logistic regression showed that previous experience, the anticipated worry reduction (peace of mind) afforded by PPI, and its perceived value for money, all had direct effects on PPI decisions. In addition, standard regression analysis found that: (1) PPI cost and level of cover significantly predicted the perceived value for money of PPI; and (2) the subjective probability of repayment difficulties predicted anticipated worry about repayment difficulties, which in turn predicted the anticipated worry reduction of PPI. In Study 2, a survey of 300 bank customers, the above direct and indirect effects on PPI decisions were further investigated by path modeling. The final path model was a good fit to the data and confirmed the main relationships described above. Thus, in addition to judgements of the value for money of PPI, worry concerning repayment difficulties, and its anticipated reduction, are strong determinants of consumer credit insurance decisions