Nanofiltration has many potential applications as a separation technology for processes that use mixtures of aqueous and organic solvents, for example alcohol/water mixtures. Membrane systems are well established for separations carried out in aqueous media, however they have seen a much slower rate of uptake in non-aqueous processes or with aqueous/organic mixtures. This is because the interaction between membrane and solvent(s) dictates both the permeability and selectivity, and there is currently limited criterion for identifying the theoretical performance of a membrane based on the properties of a bulk polymeric material. The small numbers of commercial successes to date have arisen from empirical findings, with no agreed methodology by which new candidate membrane materials can be identified. New membrane materials are required to exhibit a high permeability along with the selectivity demanded by the application. Permeability can be relatively easily manipulated using engineering solutions such as large surface areas, or very thin active separation layers. Selectivity, however cannot be manipulated in such an intuitive fashion, with the mixture type and composition, pressure and polymer characteristics all reported to be major factors. This work investigates the factors which influence the inherent selectivity of polymeric materials, and the link to nanofiltration processes. The aims of this study are to investigate the effectiveness of current theoretical and predictive tools, and to establish a technique to evaluate polymeric materials without having to fabricate a membrane. Two polymers were chosen for study which are at opposing ends of the permeability/selectivity spectrum. Polydimethylsiloxane (PDMS) and poly (vinyl alcohol) (PVA) membranes have been previously investigated in several separations involving organic-water mixtures. The materials were characterized using GPC and ATR-FTIR techniques, with ATR-FTIR further used to quantify the crosslinking content of the polymers. The total swelling degree and the inherent separation that occurs upon swelling with solvent mixtures was studied for a range of model and industrially-relevant systems, using polymer materials fabricated under different conditions. It was found that the selectivity of the polymer was a highly non-linear function of mixture type and concentration. PDMS and PVA were shown to change their affinity toward mixture components depending on the concentration, and it was hypothesized that this is due to competing mechanisms based on both molecular size and polarity. Selectivity was shown to be less dependent on the applied pressure and the degree of crosslinking, with the polymer type and mixture composition the two most dominant factors. The Flory-Huggins model was evaluated and found to give an extremely poor prediction of the selectivity in all the polymer-solvent systems studied. Further analysis was carried out using chemical potential and activity coefficient models in order to establish the sorption coefficient for future comparison with membrane filtration data. One of the key outcomes of this work is the measurement of sorption coefficients at varying composition and pressure, which can subsequently be used with existing Solution-Diffusion and Pore-Flow filtration models with greater confidence than has been possible to date.

More than half of platform petrochemicals are aromatic, whereas the only large-scale, naturally-occurring, renewable source of aromatics is lignin. Chemical depolymerization of lignin requires extreme conditions, and results in extensive destruction of the aromatic rings and/or char formation. By contrast, enzymatic lignin depolymerization occurs under mild conditions with retention of the aromatic nuclei. Therefore, laccase from Agaricus bisporus (LAB) and from Trametes versicolor (LTV) with the mediator, ABTS (2,2'-azino-bis(3 ethyl benzthiazoline-6-sulphonic acid)) were used to depolymerize lignin (sodium Iignosulphonate) under mild reaction conditions with the aim to obtain high concentrations of value-added chemicals. The depolymerization in the presence of LTV was higher than LAB, which resulted from the high catalytic activity of LTV. Lignin degradation resulted in formation of complex product mixtures. Therefore the products were fractionated and analyzed by different analytical techniques including GPC (for preliminary screening), HPLC and GCMS (for product characterization and quantification), and NMR (for fingerprint analysis). Products included guaiacol, vanillin, acetovanillone, vanillic acid, homovanillyl alcohol, phenol, 4- methyl benzaldehyde, catechol, p-toluic acid, 4- hydroxybenzaldehyde, tyrosoI, isovaniIIin, and 3-hydroxy-1-(4-hydroxy-3 -methoxyphenyl) propan-1-one, and the total yield of monomers from lignin was 9.8 % in the presence of LTV. The parameters involved in the depolymerization process were optimized to increase the yield of monomers. The efficiency of laccase mediators was also explored by the use of 2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPO), 1-hydroxybenzotriazole (HBT), N-hydroxyphthalimide(HPI) and violuric acid (VLA) in the depolymerization of sodium lignosulphonate. However, the catalytic depolymerization in the presence of these mediators was lower than ABTS. In order to improve the solubility of the substrate for the depolymerization process, screening of ionic liquids that are compatible with LAB was deployed in order to find laccase-friendly ionic liquids for further use in lignin depolymerization. The study has found [C4mim] [L-tartrate] as the best ionic liquid tested, that increased the activity of LAB by 90 %. In conclusion, enzymatic depolymerization of lignin offers a greener process than the chemical methods, and also provides a more efficient method to obtain monomers of valuable specialty chemicals under mild reaction conditions.

This research considers the role of ergonomics in consumer safety. The aim was to encourage and improve the input of ergonomics, and thus safety, into the design process. The research has resulted in a series of publications targeted specifically at designers and producers of consumer goods, with the aim of encouraging their adoption of ergonomics principles, data and methods. These publications have been produced and distributed to industry by the Department of Trade and Industry (DTI) Consumer Safety Unit: CHILDATA: The Handbook of Child Measurement and Capabilties - Data for Design Safety Designing Safety into Products: Making ergonomics evaluation a part of the design process (presented as an appendix to this thesis). The background to the research is a review of the influences on consumer safety, and the exploration of a role for ergonomics. European consumer legislation states that to be safe a product must meet the expectations of the user, hence the title of this thesis. This user-centred premise indicates the importance of product design and ergonomics in consumer safety, within the context of the other influences on safety such as safe-guarding, mitigation of accidents and education. Theoretically this places ergonomics as a central influence on safety. A review of the existing contributors to safety, such as governance, standards and education was undertaken and again design was found to be central. With the potential contribution of ergonomics to safety demonstrated, evidence of a formal relationship between ergonomics and the design process was sought from the literature. Despite many years of calls for improvements in the input of ergonomics to design, little evidence was found in the ergonomics literature of support or guidance for designers of consumer products on either of these aspects. Two main routes to improving this input of ergonomics to design were identified: the use of ergonomics data and guidelines, and the use of ergonomics evaluation methods. This research focuses on these two routes to product design safety with the hypothesis that these inputs could be improved, eventually allowing better design safety to be realised. The aims of the research were therefore to investigate and improve these inputs. The first stage of the research considered the use of ergonomics data and guidelines in design. The limitations of ergonomics data and the barriers to effective knowledge transfer were identified. Work was undertaken to address these problems, in the first instance specifically for designers of children's products. This resulted in the production of "Childata”, a handbook of ergonomics data on children, and its production and content are described. Four thousand copies of this handbook have been published and distributed free of charge to industry by the DTI. The success of Childata has resulted in sibling publications on adults (now published) and the elderly (in preparation). The next stage of the research was to consider the use of ergonomics evaluation methods by designers. A review of the literature on ergonomics methods and on guidance for their use found that there was a dearth of practical advice for designers. Also, that most guidance on evaluation methods concentrates on usability with very little reference specifically to safety. The feasibility of producing guidance for designers to encourage their use of evaluation was therefore considered. A series of four product safety evaluations were undertaken, presented here as case studies, and these form the major experimental part of the research. The aim of the case studies was to investigate the most useful and common methods for evaluating product safety and to generalise these into guidance for designers ,as well as producing formal reports and recommendations for improvements in the safety of the individual products. The products investigated were swimming pool covers, carbonated drinks bottles, all terrain bicycles and stepladders. The case studies showed however that a diversity of methods were needed to carry out the evaluations, many of which were novel methods or which drew on a mixture of ergonomics, technical and market research expertise T he only commonality found was in the sequence of stages that each evaluation followed, namely the identification of the products' users and hazards, the setting of performance criteria and selection of measurement variables, and the subsequent choice of methods. T he initial concept behind the fundamental research to producing prescriptive advice on methods was therefore rejected. Instead a framework for a generic evaluation process was developed, based on the findings from the case studies and with reference to the literature. This framework formed the basis of a guidance document for designers: ‘Designing Safety Into Products'. This was also published and distributed to industry by the DTI. The publication establishes and encourages a generic evaluation process, but also concentrates on embedding ergonomics principles into the design process by exploring the relationship between evaluation and safety and stressing the need to move past the use of ergonomics data, as well as providing methodological guidance. The research reported in this thesis has shown that the problems with the transfer of knowledge and methods from the ergonomics discipline are long standing. The reasons for this are discussed and recommendations are made to improve the link between design and ergonomics, including furthering this pragmatic approach to empowering designers by the production of similar design tools. The research programme has been a pragmatic approach to improving ergonomics and safety in design: improving the accessibility of ergonomics data for designers and promoting ergonomics evaluation methods during the product development process. The publications that have resulted from the research represent pragmatic steps which it is hoped may make some contribution to the realisation of safety.

This dissertation contributes to the empirical literature on the effects of international technology transfer on firms' productivity and employment in developing and transition countries. It combines three empirical essays which provide evidence on how participation in international activities affects firms' productivity, how it interacts with firms' absorptive capacity and how it affects firms' demand for skilled labour in 26 transition countries in Europe and Central Asia (ECA) region. The first study investigates whether foreign ownership, supplying multinationals (MNEs) located in the same country, foreign direct investment (FDI) horizontal spillovers, exporting and importing are conduits of international technology transfer and their relative importance for firms in 26 transition economies in ECA region using Business Enterprise and Environment Performance Survey (BEEPS) 2002- 2005. It contributes to the literature by analyzing the impact of all main channels of international technology transfer simultaneously and by using a firm specific measure for supply linkages with MNEs, unlike previous studies that used industry level measures. The main results suggest that foreign ownership, supplying MNEs, exporting and importing are robustly associated with higher firm productivity and we cannot reject the hypothesis that these channels are equally important. The second study examines whether international technology transfer through foreign ownership, supplying MNEs, exporting and importing depends on firm and country absorptive capacity in 26 transition economies in ECA region using the BEEPS 2002 and 2005 waves. The main contributions of this paper are that it uses firm specific measures of access to foreign technology and measures of absorptive capacity (workforce education, personnel training and R&D activities) which are closely related to the concept of absorptive capacity and less prone to measurement errors than productivity gap measures used in previous studies. Our results suggest that access to foreign technology and absorptive capacity are associated with higher productivity, but, contrary to our hypothesis, there is no evidence of an interaction effect between absorptive capacity and access to foreign technology. The third study investigates how participation in international activities affects firms' demand for skilled labour and the ways in which firms respond to changes in demand for skilled labour in 26 transition economies in ECA during the period 2002-2005 using BEEPS 2002 and 2005 waves. It contributes to the literature by studying different ways in which firms respond to changes in the demand for skilled labour (hiring employees from outside the firm or training existing employees) and by studying whether there is a causal relationship between participation in international activities and demand for skilled labour. Our results suggest that firms engaged in international activities have a better educated labour force and are more likely to train their employees than domestic firms. However, this happens because firms with better skilled workforces and with formal training programmes select into participating in international activities, and not because these firms upgrade the skills of their workforces after starting to participate in international activities.

Predicting flavour perception is complicated by interactions occurring both within and across sensory modalities, but understanding these interactions and the resulting multimodal integration is crucial to the formulation of successful products. Despite the commercial appeal of carbonated soft drinks, few studies have examined the effects of tastant: aroma: carbonation interactions on sensory perception. To facilitate these investigations, a citrus flavoured model beverage was created containing ingredients common in commercial beverages; water, aroma volatiles, sugar (glucose or fructose; equi-sweet levels), and acid (citric and lactic acid; equi-sour levels). The complexity of the beverage was gradually increased (influence of carbonation and caffeine) until the model beverage contained elements capable of stimulating gustatory, olfactory and trigeminal systems. Samples, selected according to D-optimal designs, were evaluated instrumentally (APCI-MS measuring volatile release, rheological measures of viscosity), and sensorially (using a trained panel of assessors). Predictive polynomial models were generated from mean panel data to explain variations in the attributes as a function of the design factors. The model beverages provided evidence that multi-modal interactions occurred within this model beverage system. Increasing both sugars and acids resulted in an increase in perceived citrus flavour which was not related to any alteration in volatile release measured instrumentally. Intriguingly, glucose and fructose showed different flavour perception enhancement profiles despite being used at perceptually equi-sweet levels. This difference between the monosaccharides was also evident in the predictive models generated for mouthfeel attributes. 'Overall fizziness' was dependant only on carbonation level and unaffected by levels of tastants. However, varying levels of glucose impacted on 'tingling', a relationship not mimicked by fructose. Addition of carbonation increased perceived sourness, in agreement with previous literature, but results also demonstrated a suppressive effect on perceived sweetness. Interestingly, evaluation of non-caffeinated beverages revealed the perception of a bitter aftertaste, which was primarily driven by CO2 level, enhanced by citric acid, and suppressed by increasing sugar concentration. In caffeinated beverages, however, caffeine concentration was the main influence on 'bitterness' and 'bitter aftertaste' attributes. Despite beverage manufacturers including caffeine as 'flavouring' there was little evidence to suggest caffeine concentration modified perception of citrus flavour in this system. This project provides a comprehensive assessment of the sensory profile of a model carbonated beverage. Combining instrumental and sensorial analysis provided novel evidence of the influence of multi-modal interactions on sensory perception, and highlights the differential effects of two monosaccharides on several key sensory attributes.

Long term (>2 years) failure of UHMWPE components in-vivo is predominantly caused by wear of the UHMWPE component. The surface properties of UHMWPE greatly influence the adhesive and abrasive mechanisms of wear that occur in the hip. However, there is not a clear understanding of how in-vivo wear mechanisms influence surface mechanical properties of UHMWPE. In addition, previous researchers have reported wear rates for Charnley UHMWPE acetabular components that vary considerably between patients. It is conceivable that these variations in wear are a result of variations in the surface mechanical properties of UHMWPE. This study used a combination of instrumented indentation testing and Ff-IR imaging to assess the depth dependent micromechanical and chemical properties of 32 retrieved UHMWPE acetabular components. Significant variations in the mechanical and chemical properties of samples taken from worn and unworn regions of retrieved UHMWPE acetabular components were found. In unworn regions, these variations were principally caused by post-irradiation ageing. However, in worn regions, the variation in properties was primarily caused by the wear process.

Photocuring of polymers and polymer composites, from epoxy resin based formulations, has been of growing interest over the past two decades. The photocuring occurs when an epoxy formulation is exposed to electromagnetic radiation, usually ultraviolet (UV) radiation. This process has been explored widely and it can be described as an open mould process by which the epoxy formulation is exposed directly to the radiation. However, for a closed mould process, thermal curing, rather than radiation curing, typically is employed. The potential of using photocuring for a closed mould process has not yet been investigated in detail. The challenge in photocuring of polymers and polymer composites in a closed mould is directing the radiation into the mould to activate the photocuring process, which is not possible using the conventional methods. Hence, for this reason the present work is focused on the development of a closed mould photocuring system using side emitting optical fibres. This photocuring system using side emitting optical fibres relies upon the optimisation of epoxy based resins. As a result, an extensive characterisation of different types of UV curable cationic epoxy resins is carried out using two pre-formulated commercial resins, formulations from bisphenol A/F, and formulations from cycloaliphatic epoxy. The formulations showed different reactivity and hardness. An important result is that the cycloaliphatic epoxy resin formulations cured much faster than the other bisphenol A/F formulations, having a more uniform hardness distribution and UV radiation transparency during the curing. Side emitting optical fibres are adopted to photocure epoxy in a closed mould. Different types of side emitting optical fibres are characterised to determine irradiation efficiency. The optical fibres had either a silica core or a PMMA core. The silica core fibres have a silicone cladding containing radiation scattering particles (either ZnO or Al2O3) and diffuser (either PA6 or ETFE). The PMMA core polymer optical fibres (PMMA POFs) have a PVDF cladding with micro-perforations as a side emission mechanism. Silica core fibres with the Al2O3 scattering particles and the PMMA core fibre are more suitable for the closed mould application as they transmitted efficiently in the UV radiation band. The high side emission characteristics of the PMMA POF compared to the silica core fibre showed higher potential for use in the closed mould photocuring process. As the polymerisation speed is influenced by the amount of flux density of the radiation source, a high flux lamp (Hg lamp, 40 W/cm2) is coupled to the side emitting optical fibres. This lamp caused thermal degradation to the PMMA POF at the launch point when in use. A cooling device is made to minimise the thermal degradation generated by radiation absorption. After improving the optical transmission stability of the PMMA POF, its side emission is enhanced by various treatments, such as permanent modification of the fibre geometry with adjusted bend radii as well as by mechanically embedding silica scattering particles into the fibre and applying micro-cuts. The developed, closed mould photocuring system consists of: enhanced side emitting PMMA POF, a cooling device, high emission Hg lamp, and a closed mould setup. 1.5 mm and 5 mm thick components, made from an optimised epoxy formulation (based on cycloaliphatic epoxy), are cured using the photocuring system. The 1.5 mm thick component (20 mm wide and 245 mm long) is cured in 45 minutes using a single PMMA POF treated with silica particles (side emission of ~81 % of the total launched emission). The 5 mm thick component (75 mm wide and 170 mm long) partly cured in 45 minutes by simultaneously using three PMMA POFs treated with silica particles and geometric modification (side emission of ~96 % of the total launched emission). This sample eventually cured with time (up to 36 hours) due to dark reaction. The efficiency of the developed closed mould photocuring system is validated by curing a 1.5 mm thick component made from a pre-formulated polyester resin formulation. This component cured in 7 minutes (30 mm wide and 245 mm long) using a single PMMA POF treated with silica particles.

The present study was undertaken to investigate issues concerned with the endurance to muscular loads created by the holding of static postures, without the presence of any other form of muscular effort. Its main aim was to explore the possibilities for the development of models which are expected to account for the capacity to endure such kind of exertion. Upright standing postures, with both arms abducted, were held by young male and female subjects (age 18-24 yr.) for as long as they could, until sensations of physical discomfort, rated on a scale with marks between 0 and 10 (Borg, 1982), became unbearable and forced them to abandon the posture. The study was constituted by two main experimental stages. In the first one, a posture as described above, with arms abducted at 60°, was used to submit to the test a model developed in 1985 by N. P. Milner (Milner's model). Although this model was originally proposed as a means to predict the remaining proportion of the maximum endurance (or 'recovery') left to the subject after a single sequence of work and rest, where work consisted of the holding of a stooped posture, its author affirmed it could be applied to any posture. The results of the testing, performed on six female subjects, demonstrated that Milner's model cannot predict with reasonable accuracy the 'recovery' for the upright standing posture with abduction of both arms. Apparently, the assumptions made by Milner concerning the relationships between the endurance capacity and the length of work and rest in a stooped posture did not apply to the test posture. The second experimental stage had three aims. The first was to test the repeatability of the endurance to standing postures with abduction of both arms. The maximum holding time for postures with arms abducted at 30°, 60° and 90° was measured on three occasions on a sample of five male and five female subjects. The maximum holding time for each of the three postures exhibited a wide variability between subjects, but when compared between the repeated measurements, the average value for the whole sample did not exhibit a significant difference. Also, male subjects had, on average, longer holding times than females, but there was a substantial overlap of the individual values. The second aim was to investigate the pattern of growth of the discomfort ratings over the length of the maximum holding time. This was found to be of a very strong linear nature, evident in all three postures studied and very similar for men and women. The strength and consistency of this relationship suggest that it may be used as a model to predict either the endurance capacity in function of the rate of growth of discomfort ratings, or the degree of discomfort that a certain length of holding will provoke. The third aim was to establish whether pure postural loads will provoke changes in the myoelectric activity which indicate the presence of heavy localised muscular fatigue. Mean power frequency (MPF) and RMS amplitude of the EMG signal were monitored throughout the 90 trials of posture holding. Significant changes were evident, with MPF decreasing and RMS amplitude increasing in most of the trials. This means that the posture, even at the lowest angle did provoke muscular fatigue. Another finding, rarely documented, was the presence of electromyographic changes that went in the reversed direction, i. e., MPF increased whilst RMS amplitude decreased. Finally, no well-defined pattern could be established for the time course of those changes or for their relationship with the discomfort ratings.

This study explores the usage of linear programming (LP) as a tool to optimise the parameters of time series forecasting models. LP is the most well-known tool in the field of operational research and it has been used for a wide range of optimisation problems. Nonetheless, there are very few applications in forecasting and all of them are limited to causal modelling. The rationale behind this study is that time series forecasting problems can be treated as optimisation problems, where the objective is to minimise the forecasting error. The research topic is very interesting from a theoretical and mathematical prospective. LP is a very strong tool but simple to use; hence, an LP-based approach will give to forecasters the opportunity to do accurate forecasts quickly and easily. In addition, the flexibility of LP can help analysts to deal with situations that other methods cannot deal with. The study consists of five parts where the parameters of forecasting models are estimated by using LP to minimise one or more accuracy (error) indices (sum of absolute deviations – SAD, sum of absolute percentage errors – SAPE, maximum absolute deviation – MaxAD, absolute differences between deviations – ADBD and absolute differences between percentage deviations – ADBPD). In order to test the accuracy of the approaches two samples of series from the M3 competition are used and the results are compared with traditional techniques that are found in the literature. In the first part simple LP is used to estimate the parameters of autoregressive based forecasting models by minimising one error index and they are compared with the method of the ordinary least squares (OLS minimises the sum of squared errors, SSE). The experiments show that the decision maker has to choose the best optimisation objective according to the characteristic of the series. In the second part, goal programming (GP) formulations are applied to similar models by minimising a combination of two accuracy indices. The experiments show that goal programming improves the performance of the single objective approaches. In the third part, several constraints to the initial simple LP and GP formulations are added to improve their performance on series with high randomness and their accuracy is compared with techniques that perform well on these series. The additional constraints improve the results and outperform all the other techniques. In the fourth part, simple LP and GP are used to combine forecasts. Eight simple individual techniques are combined and LP is compared with five traditional combination methods. The LP combinations outperform the other methods according to several performance indices. Finally, LP is used to estimate the parameters of autoregressive based models with optimisation objectives to minimise forecasting cost and it is compared them with the OLS. The experiments show that LP approaches perform better in terms of cost. The research shows that LP is a very useful tool that can be used to make accurate time series forecasts, which can outperform the traditional approaches that are found in forecasting literature and in practise.

While oxy-fuel combustion research is developing and large scale projects are proceeding, little information is available on oxy-biomass combustion and cocombustion with coal. To address this knowledge gap, this research conducted has involved comprehensive laboratory based fundamental investigation of biomass firing and co-firing under oxy-fuel conditions and compared it to conventional air firing conditions. First, TGA was employed to understand the fundamental behaviour of biomass devolatilisation, char combustion and nitrogen partitioning between volatiles and residual char. The results revealed that C02 did not have effect on the devolatilisation of sawdust at temperatures below 1100 grad. C due to higher mass transfer resistance of primary volatiles in C02 than in N2 at low temperatures. Secondly,. by optimising the devolatilisation procedure in a combustion system that simulates closely to an industrial scale such as drop tube furnace (DTF), the devolatilisation/char combustion characteristics of sawdust was investigated. The effect of CO2 on volatile yields, nitrogen partitioning and char burnout were all significant in relation to N2• While coal combustion additives are being used to enhance coal burnout, this study observed improved coal char burnout when biomass char was co-fired with coal char, again a faster burnout was observed in oxy-firing condition compared to air firing. This was due to the catalytic effect of biomass inherent alkali and alkaline earth metals. Similarly, improved volatile yields were observed during codevolatilisation. These fundamental results have provided insight into oxybiomass' firing and co-firing and the data can be used in appropriate CFD modelling to aid the design of oxy-biomass co-firing burners.