High demand of Liquefied Natural Gas (LNG) in recent time requires LNG carriers in more frequent operations in order to meet customers' needs. To ensure that the LNG carriers are always reliable in service, it has become necessary to adopt various advanced modelling techniques such as Genetic Algorithm (GA), fuzzy logic and Evidential Reasoning (ER) for risk/safety assessment and maintenance modelling of LNG carrier operations. These advanced computational techniques can help to overcome challenges posed by uncertainties associated with the LNG carrier operations. Their usefulness is demonstrated using case studies in this research. Firstly, two major hazards of LNG carrier operations such as "failure of LNG containment system" and "LNG spill from transfer arm" are identified and estimated as high risk ones using a risk matrix technique and expert judgement. The causes (failure modeslbasic events) of these high risk hazards are analysed using a Fault Tree Analysis (FTA). The failure logics of their failure modes are established and Boolean algebra is applied to facilitate the evaluation of the failure probabilities and frequencies. Secondly, a GA model is developed to improve the safety levels of the LNG containment system and transfer arm, to minimise their maintenance costs and to realise optimal resource management. The GA is used to optimise a risk model that is developed with exponential distribution and parameters such as failure frequencies, unit costs of maintenance and new maintenance costs of the LNG containment system and transfer arm. Thirdly, the uncertainties of some parameters in the GA model such as unit costs of maintenance are subdued using the strength of Fuzzy Rule Base (FRB) in combination with GA. 125 fuzzy rules of LNG carrier system maintenance cost are developed, which makes it possible to facilitate the evaluation of maintenance cost in any specific LNG risk-based operation. The outcomes of unit costs of maintenance are used in the GA based risk model to update the optimal management of maintenance cost. Finally, the uncertainties of failure modes of the LNG containment system and transfer arm are investigated and treated based on the Formal Safety Assessment (FSA) principle using a Fuzzy ER (FER) approach. The fuzzy logic is used to estimate the safety/risk levels of those failure modes while the ER is used to synthesise them to facilitate the estimation of safety/risk levels of the top events. Risk Control Options (RCOs) are developed to manage high level risks. The costs for each of the RCOs are estimated and synthesised using ER, which facilitated the investigation of the best RCOs in risk-based decision making. There is no doubt that the methodologies proposed possess significant potential for use in improving safety and maintenance of LNG carrier operations based on the verifications of their corresponding test cases. Accordingly, the developed models can be integrated to formulate a platform to facilitate risk assessment and maintenance management of LNG carrier systems in situations where traditional techniques cannot be applied with confidence.

No description available.

The present research is concerned with investigating the structural effect of using steel fibre-reinforcement on the punching shear behaviour of ground-suspended slabs with internal columns. The main objectives of this research were to develop a constitutive model for steel fibre-reinforcement (SFRC), to study experimentally the punching shear behaviour of SFRC with no longitudinal reinforcement and to develop a finite element model that can accurately predict the behaviour of SFRC slabs subjected to punching shear. In this respect, a literature review of the work undertaken by previous researchers on punching shear behaviour of concrete slabs is presented. After that, a constitutive model for SFRC was developed. This is followed by a preliminary finite element analysis (FEA) and experimental study of SFRC slabs. Finally, a finite element model was developed. The literature review revealed that little work has been carried out to study the effect of fibre-reinforcement on the punching shear capacity of concrete slabs. Furthermore, structures, hence a thorough investigation in this area was mandatory. A constitutive model for SFRC in post-cracking stage was developed. This enables one to estimate the tension stiffening behaviour of SFRC based on a simple beam bending test and a statistical model developed in this research, this constitutive model was used later on in the modelling of the SFRC slabs using FEA. In the preliminary FEA, sufficient information for the size and the design of test specimens that were used in the experimental programme was produced. In the experimental study, eight steel fibre-reinforced concrete slab-column connection specimens were tested. The variables of the test specimens include the concrete compressive strength, fibre dosage and fibre aspect-ration.

A chemical supply chain (CSC) presents a network that integrates suppliers, manufacturers, distributors, retailers and customers into one system. The hazards arising from the internal system and the surrounding environment may cause disturbances to material, information and financial flows. Therefore, supply chain members have to implement a variety of methods to prepare for, respond to and recover from potential damages caused by different kinds of hazards. A large number of studies have been devoted to extending the current knowledge and enhancing the implementation of chemical supply chain risk management (CSCRM), to improve both safety and reliability of the CSCRM systems. However, the majority of existing risk management methods fail to address the complex interactions and dynamic feedback effects in the systems, which could significantly affect the risk management outcomes. In order to bridge the gaps, a new CSCRM method based on System Dynamics (SD) is proposed to accommodate the need to describe the connections between risks and their associated changes of system behaviour. The novelty of this method lies not only on providing a valid description of a real system, but also on addressing the interactions of the hazardous events and managerial activities in the systems. In doing so, the risk effects are quantified and assessed in different supply chain levels. Based upon the flexibility of SD modelling processes, the model developer can modify the developed model throughout the model life cycle. Instead of directly assessing different risks and providing arbitrary decisions, the obtained numerical results can offer supportive information for assessing potential risk reduction measures and continuously improving the CSC system performance. To demonstrate the applicability of the newly proposed method, a reputed specialty chemical transportation service provider in China is used and analysed through modelling and simulating the chemical supply chain transportation (CSCT) operations in various scenarios. It offers policy makers and operators insights into the risk-affected CSC operations and CSCRM decision-making processes, thus helping them develop rational risk reduction decisions in a dynamic environment.

Made available in DSpace on 2014-06-11T19:30:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-28Bitstream added on 2014-06-13T20:40:09Z : No. of bitstreams: 1 ingino_raj_me_araiq.pdf: 2361029 bytes, checksum: 2c11adc7a8fb7199ea06addc95fd0823 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste projeto foram obtidos pós fotocatalíticos de TiO2/SnO2 modificados com Ag2O, utilizando o método dos precursores poliméricos (Pechini). A composição dos óxidos foi TiO2(75%)/SnO2(25%) e o agente modificador Ag2O nas concentrações: 0,01, 0,05, 0,10, 0,50 e 1,00 mol%. Estes óxidos foram analisados utilizando difratometria de Raios X (análise da cristalinidade), área superficial (SBET – análise de area superficial), FEG/MEV (análise da morfologia das partículas), XPS (análise das interações atômicas na superfície) e espectroscopia de refletância difusa (no ultravioleta-visível - UV-Vis – análise do “band-gap” dos óxidos). As atividades fotocatalíticas foram medidas, utilizando um reator montado em nossos laboratórios, realizando a fotodecomposição de soluções de Rodamina B, catalisada pelos óxidos em estudo, em um estudo da descoloração proporcional que foi medida em um espectrofotômetro no comprimento de onda de 300 a 700nm. Os estudos de atividade fotocatalítica foram realizados tanto em lâmpada UV como na luz solar e os resultados foram semelhantes, ou seja, obteve-se um óxido com o mesmo comportamento na luz solar. Estes estudos foram realizados para comparar a mudança na atividade fotocatalítica ao variar a concentração do agente modificador (Ag). Verificou-se que durante o processo de calcinação surgem aglomerados nos óxidos fotocatalisadores, que podem degenerar o efeito da fotoatividade. Obteve-se pós com fotoatividade catalítica, que apresentaram degradação da Rodamina B em 11 minutos, valor próximo aos 9 minutos obtidos para a degradação utilizando P25 (DEGUSSA), que é um óxido comercial amplamente utilizado e estudado / In this project, photocatalytical TiO2/SnO2 powders modified with Ag2O were obtained by the polymeric precursor method (Pechini). It were obtained to result in a final oxide composition of: TiO2(75%)/SnO2(25%) and the modifying agent (Ag2O) concentration: 0.01, 0.05, 0.10, 0.50 and 1.00 mol%. This powders were analyzed using X-Ray diffractometry (to analyze the phases formed), superficial area (SBET), by FEG/SEM (to analyze the superficial characteristics), XPS (to analyze the superficial atomic interaction) and diffuse reflectance spectroscopy (on ultraviolet visible - UV-Vis - to analyze the powders band-gap). The photocatalytic activities were measured, using a homemade reactor, during the decomposition of Rodhamine B (RB) solutions, in a study of the proportional discoloration measured in a scanning spectrophotometer in the wave length 300 to 700nm. The RB decomposition studies were carried on both UV-lamp and sun-light and the results were similar, this means that were obtained an oxide with the same behavior on sun-light. This was made to compare the photocatalytic activity when varying the modifier agent concentration (Ag). It were also verified that during the calcination process that some agglomerates evolves and that can degenerate the photocatalytical effect. It were obtained photocatalytical powders, that degenerate RB in 11 minutes, close to the 9 minutes obtained by degradation using P25 (DEGUSSA) that is a commercial oxide widely used and studied

The work presented in this thesis reports the development of a non-stick coating for bakeware from renewable materials. Also investigated is the use of epoxidised vegetable oils for renewable polyesters and nanocomposites. Chapter 1 provides a brief introduction to materials from renewable sources leading to a more detailed overview of triglyceride chemistry and finishes with a brief background of non-stick coatings. Chapter 2 presents the development of the non-stick coating. Current commercial coatings were analysed identifying the key components that could be replaced with more environmentally friendly alternatives. Thermal and photo-initiated curing regimes were studied on a range of epoxidised vegetable oil monomers for use as a polymer binder. Thermally cured epoxy soybean oil using a sulfonic acid catalyst was deemed superior. Additives to this resin such as silica, pigments and solvents were investigated to produce a coating formulation which was analysed by TGA and industry standard surface tests including pencil hardness, flexibility and cross-hatching. Chapter 3 reports the hydrosilylation reaction on vegetable oils. A model system with fatty acids and triethylsilane was proposed which lead to the formation of crosslinked silicone rubbers using di- and polyfunctional silanes and vegetable triglycerides. Epoxy fatty acid – silicone hybrids were used as release agents in the non-stick coating formulation described above. Chapter 4 focuses on the ring opening polymerisation of epoxidised vegetable oils with cyclic anhydrides forming crosslinked polyesters. Mechanical properties such as tensile strength, elasticity and Young’s modulus were measured as well as thermal analysis (TGA, DSC and DMTA). It was found that the physical properties were related to the crosslinking density with a higher density lead to strong but brittle polymers whereas lower crosslinking density samples were soft and elastic. The crosslinking density could be controlled by the choice of the vegetable oil type, anhydride type and the epoxide : anhydride ratio. Chapter 5 uses these polyester resins in the formation of nanocomposites. Nanocomposites were created using hollow silica shells and polyaromatic hydrocarbons and the mechanical properties measured and compared to the vegetable oils resins alone and other work in this area. This was followed by the copolymerisation of epoxy vegetable oils and styrene oxide and blends of grapessed and euphorbia oils with different epoxide functionality. It was found that blends could achieve properties of both oils such as high strength and elasticity in the same polymer sample. Chapter 6 describes the experimental procedures and chemical analysis of reactions performed in this thesis.

Increasing global ethanol consumption has revived research into a variety of route for the synthesis of ethanol. One such route is via the hydrogenation of acetic acid, for which a catalyst with significant acid tolerance is required. The objective of finding an active, acid tolerant base metal catalyst was central to this project. In this study, a commercial methanol synthesis catalyst was initially investigated for its viability as an acid hydrogenation catalyst, following the production of ethanol when acetic acid was passed over it in a different study [1]. The methanol synthesis catalyst was not a viable option due to deactivation, but the use of a copper based system was shown to be active, in line with other studies [2]. Copper based catalysts were tested in both integral and differential reactor systems. The copper catalysts, with metal loadings of 5 wt.% and 10 wt.%, showed some activity towards the production of ethanol, but not in comparable quantities to those observed with the high copper content methanol synthesis catalyst. The effect of higher acetic acid concentrations, up to 20 mol.%, within an atmospheric fixed bed system were investigated, and showed that copper based catalysts were physically compromised by the presence of acetic acid. Deactivation and degradation of this catalyst upon exposure to acetic acid, especially at higher concentrations, meant that it was not appropriate for this process. The propensity of the copper catalysts to degrade in the presence of acetic acid led to other base metal systems being investigated, in the form of nickel and cobalt catalysts. All three base metal systems were investigated within a differential reactor to show direct comparisons of each catalyst at 10 wt.% and 20 wt.% metal loadings. This research showed that cobalt based systems were the most active of the metals tested at the two separate loadings. A study into the effect of the catalyst support using an 10 wt.% cobalt loading, on a range of supports, showed that alumina was the superior support for the selective hydrogenation of acetic acid to ethanol. The other supports investigated were silica, titania and zinc oxide. Comprehensive testing of the catalysts prepared with cobalt, copper and nickel, identified that the 20 wt.% cobalt on alumina was the most stable, in terms of activity and catalyst integrity, and active catalyst of those investigated at an optimal reaction temperature. 1. Blain, S., Ditzel, E., and Jackson, S. D., A mechanistic study into the effect of acetic acid on methanol synthesis. Catal. Sci., 2012. 2(4): p. 778-783. 2. Cressely, J., Farkhani, D., Deluzarche, A., and Kiennemann, A., The Evolution of Carboxylate Species in the Framework of CO-H2 Synthesis - Reduction of Acetic-Acid on the Co,Cu,Fe System. Mat. Chem. Phys., 1984. 11(5): p. 413-431.

The rapid depletion of fossil fuel reserves and concurrent increase in global temperatures has resulted in global demand for the production of alternative environmentally friendly fuels. First-generation biofuels that utilise cash crops for the extraction of fermentable sugars currently exist, but are highly controversial due to socioeconomic and environmental reasons such as diverting food production or deforestation. Therefore, second-generation biofuels that utilise lignocellulosic waste materials are a more attractive prospect. In Europe, lignocellulosic biomass wastes such as wheat straw, display great potential for the production of alternative energy sources such as bioethanol for transportation. Conversion to this biofuel requires microorganisms that will effectively utilise the constituent sugars to produce a high yield of product. Saccharomyces cerevisiae (S. cerevisiae) strains possess the most desirable phenotypes for this objective. However, the components of wheat straw are difficult to break down, therefore pretreatment is required. Pretreatment methods vary but often utilise various chemicals that produce compounds that are inhibitory to yeast. This affects the efficiency of fermentations. The focus of this work is on formic acid and a synthetic media containing the main inhibitor compounds released during pre-treatment of steam exploded wheat straw. Six pair-wise F1 crosses between four distinct parental S. cerevisiae clean lineage populations have been generated previously by Cubillos et al., 2009. The 96 F1 progeny from each cross have been assayed for tolerance phenotypes in order to determine QTLs (Quantitative Trait Loci), which will enable us to map genes contributing to the multi-genic trait of inhibitor tolerance. Overall, three QTLs were identified for formic acid and five QTLs were identified from the synthetic inhibitor mix. Candidate genes were selected from the QTL analysis and were tested by performing reciprocal hemizygosity assays to determine which genes are responsible for inhibitor resistance to enable the development of yeast strains suitable for second-generation biofuel production.

The increasing concern of energy shortage and environmental pollution attracts worldwide exploration of using sustainable biomaterials for the production of biofuels and biochemicals. Utilising lignocellulosic raw materials for valuable bio-products production is generally considered as a preferred biosynthetic technology. Although various processes have already been proposed, lignocellulose hydrolysis is still remaining as one of the major challenges that prevents wide spread application of lignocellulosic raw materials in biofuel and biochemical production. The aim of this study was to investigate the feasibility of applying soft-rot fungi as a biological pretreatment of wheat straw for the generation of cellulase enzymes and then use the freshly produced enzymes to hydrolyse the fermented wheat straw to a sugar rich hydrolysate. The wheat straw hydrolysate had also been examined for the production of bioethanol and biochemicals, such as succinic acid and itaconic acid. Solid State Fermentations (SSF) of wheat straw were carried out using both Aspergillus niger and Trichoderma reesei. The fermentation conditions, such as moistures content, culture time, addition of nutrients, and modification of wheat straw were optimised for the production of cellulase. In a SSF using autoclaved wheat straw, an enzyme activity of 9.5 FPU/g was achieved. When 0.5% yeast extract and mineral solution were added, the enzyme activities increased to 24.0 FPU/g after 5 days of cultivation. In a SSF of an alkali soaked wheat straw (wheat straw treated with 1% NaOH at 25˚C for 24 hours), 21.8 FPU/g was obtained after just 1-day culture. Optimisation of hydrolysis process led to a hydrolysate containing 59.8 g/L glucose, which was achieved from the hydrolysis of biologically pretreated wheat straw at 18% solid loading, with an enzyme loading rate of 55 FPU/g at 50˚C. Fermentations using the wheat straw hydrolysate resulted in 28.6 g/L ethanol, which was equivalent to 93.4% of theoretic yield. Utilisation of wheat straw hydrolysate for succinic acid production was investigated using recombinant yeast strains. For Saccharomyces cerevisiae D2, the deletion of SDH1 and SDH2 genes enhanced succinic acid production by 68%. Optimisation of fermentation conditions and fermentation scales led to a succinic acid production to around 12 g/L, which was nearly 100-folds of what succinic acid production using the wild S. cerevisiae D2 strain at initial fermentation conditions. Use wheat straw hydrolysate to replace commercial glucose based semi-defined medium resulted in the same succinic acid production yield, but lower concentration due to the low sugar concentration in the hydrolysate. Biosynthesis of itaconic acid using wheat straw hydrolysate was also explored, but no significant itaconic acid production was observed.

The synthesis and characterisation of a variety of zeolites and aluminosilicates has been achieved using hydrothermal methods and solid state calcinations. The system using elemental aluminium, silica and sodium hydroxide solution as starting materials was explored using hydrothermal methods (200°C), and reactions conditions were optimised for the formation of analcime, sodalite, zeolite A and faujasite. All materials were characterised using powder x-ray diffraction. The thermal conversion of zeolite A and sodium chloride into sodalite has been studied using combined TGA and DTA analysis and time resolved powder neutron diffraction heating up to 800°C. It was found that the thermal conversion occurred at 550°C and no intermediate phases were observed during this transition. The synthesis and characterisation of a range of reversibly photochromic sodalites has been achieved via thermal processing of zeolite A with sodium sulphate and a variety of group I metal salts. All of the sodalites adopt the space group P-43n and were characterised by powder neutron diffraction and Rietveld refinement. Structural refinements show that substitutions at non-framework sites alter the framework bond distances of the sodalite and the observed optical property. Different colours of reversible photochromism have been observed and tailored by use of different salts in the synthesis, and trends between structure and optical property have been examined. Synthesis of the anhydrous zeolite type phase K2Al2Si3O10(KCl) with edingtonite topology has been achieved using a high temperature, high pressure reaction (600°C, 7000psi). Rietveld refinement of powder x-ray diffraction in the space group P-421m was performed. The tetragonal unit cell was found to have refined lattice parameters of a = 9.7488 and c = 6.4879. Structural considerations have been examined as to the inaccessibility of the analogous rubidium phase. Several different methods for formation of zeolite films have been investigated, and the properties of these films compared with view to thermal processing of the films, or forming the basis of a high throughput solid state array. Films were characterised using powder x-ray diffraction and scanning electron microscopy. Thermal processing of the zeolite films was performed to collapse the zeolite into a reversibly photochromic sodalite.