Predictions of turbulent boundary-layer developments using a two-equation model of turbulence

Imperial Users onl

Physical and Electrical Properties of Zinc-Magnesium-Phosphate Glasses

Glasses in a wide range of composition in the ternary system x(ZnO)-y(MgO)-z(P2O5) where x ranges from 5 to 20 mol %, y ranges from 5 to 20 mol % and z ranges from 50 to 70 mol % have been prepared by traditional melt quenching technique with ZnO, MgO and P2O5 as the starting raw materials. X-ray diffraction (XRD), refractive index and electrical properties have been used to characterize the structural, optical and electrical features. All the sample glasses at present work have been confirmed to be amorphous by X-ray diffraction technique using Philips Model 7602 EA Almelo. The refractive indices of ternary glasses were measured by Ellipsometer and were found to agree with Lorentz-Lorenz equation where the refractive index increased with the increase of the density (ρ) and the decrease of the molar volume (Vm) of the glass. The density of the glass was determined by Archimedes Principle. From the empirical data, other values such as molar volume and molar refractivity have been computed. The variations in the molar volume were resulting in variation on the density and refractive index of the glasses. From the results obtained, it is obvious that the refractive index varies with molar refractivity, which depends on the polarizability of the ions, density and molecular weight in the sample glass. Those physical properties were found to be sensitively depending on its composition. Electrical conductivity (σ) was measured in the temperature 30 oC to 300 oC. Conductivity for the ternary series glasses increased with addition composition of ZnO or MgO with temperature. Activation energy (Ea) was calculated by the slope of graph log σ versus 1000/T with Arrhenius equation. The values of activation energy in the ternary series were recorded in the range of 0.023 eV to 0.112 eV

The distributed computer system

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University

Twin screw extrusion pre-treatment of wheat straw for biofuel and lignin biorefinery applications

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Pre-treatment of wheat straw(lignocellulosic) biomass is a crucial step as it has direct impact on the subsequent yield of enzymatic saccharification and alcohol fermentation processes in the production of biofuel. Twin screw extrusion is a highly feasible pretreatment method and has been received great interest in the recent year pre-treatment studies. Twin screw extrusion is a continuous process, where the biomass feedstock can be subjected to a combination of simultaneous physical, thermal and chemical treatments. Steam explosion is a batch process and is the most commonly used method for lignocellulosic pre-treatment. In the initial stage of this study, the yield of glucose obtained from enzymatic saccharification for both methods (extrusion and steam explosion) were compared to identify the most effective pre-treatment approach. Effectiveness of the conventional steam explosion pre-treatment was used as benchmark for the directions of development of effective extrusion fractionation for wheat straw. In subsequent study, the impact of physical operating parameters (moisture, barrel temperature, compaction, screw speed and size reduction before extrusion) over twin screw extrusion with and without NaOH were studied. Low temperature (50°C) and increased moisture extrusion were preferred extrusion conditions. Yield of glucose can be improved by addition of NaOH (0.04g / g straw) and barrel temperature profile optimisation. Post extrusion washing was recommended. Findings from FTIR and TGA help to understand the chemical and structural changes took place in the pre-treatment and can be correlated with the glucose yield at the end of enzymatic hydrolysis. Characterisation analysis was extended to FT-NIR, morphology, crystallinity and specific surface area analysis to analyse the structural changes of lignocellulose biomass in extrusion pre-treatment and correlation with glucose yield. Chemometric analysis was used to statistically process large amounts of spectral data. The PCA scores plots showed good cluster segregation of the samples and were thus able to distinguish the effects of different pre-treatment conditions. The PLS regression models for both FTIR and FT-NIR showed good statistical regression and predictive ability correlated to the glucose yield. For the lignin ultilisation study, crude lignin was recovered from black liquor and fractionated with solvents. Lignin and the fractions were characterised with solvent solubility, SEC, UV, FTIR, 1H and 13C NMR and evaluated for the antioxidant activity with AAI ranged from 0.3 to 2.4. Reason for the low performance was proposed and experiment was extended to the intended application performance screening. Lignin application study was further extended to assess the feasibility of using lignin as an antioxidant in carboxylated acrilonitrile-butadiene rubber, XNBR glove. Evaluation involved physical observation, mechanical properties and thermal analysis – DSC-OIT after incorporation of lignin into XNBR glove. Lignin antioxidant performance was compared with current chemical antioxidant in used in industry. A part from antioxidant behaviour, lignin was also found can enhance the softness of XNBR film after accelerated heat aging.This study is funded by the Ministry of Science, Technology and Innovation, Malaysia

From Paintings to Opera: Discovering the Reimagination of William Hogarth's A Rake's Progress in Igor Stravinsky's The Rake's Progress

The Rake?s Progress (1951) is a well-known satirical opera in three acts with an epilogue by Igor Stravinsky (1882-1971), with a libretto written by Wystan Hugh Auden (1907-1973) and Chester Kallman (1921-1975). This opera is based on William Hogarth?s (1697-1764) series of eight paintings, A Rake?s Progress (1734), which inspired Stravinsky during his visit to the Art Institute of Chicago on May 2, 1947. Even though many scholars have conducted discussions on the opera itself, there is little scholarship on the influence of Hogarth?s paintings on Stravinsky?s opera. This dissertation considers how Stravinsky, Auden, and Kallman translated Hogarth?s series of satirical paintings into a period opera to which audiences in the mid-twentieth century could relate. As I am a collaborative pianist that works extensively with singers and opera projects, I aim for this document to be helpful as a guide for singers, vocal coaches, or other interested individuals who wish to have a fresh perspective on this opera. I have divided this dissertation into three parts. In the first part of my disquisition, I investigate Stravinsky?s motivation to write this opera by researching the societal culture, in both early-eighteenth-century London and the mid-twentieth-century United States. In the second part of this paper, I track the collaborators' creative decisions in altering the opera's narrative. I review the libretto of the opera and the iconography of Hogarth?s series of paintings which consists of religious and cultural symbols reflecting Hogarth?s perspective on morality during his time. I also consult modern scholarships in interpreting the narrative and proceed to establish the relationship between the libretto and Hogarth?s paintings. In the third part of this dissertation, I critically analyze selected arias of the opera to investigate how Stravinsky employs neoclassicism in bringing the libretto to life in the music. Ultimately, this dissertation provides a fresh perspective on Stravinsky?s opera by giving a better understanding of Hogarth?s views on morality and culture in eighteenth-century London through his series of engravings as well as how Stravinsky, Auden, and Kallman translated Hogarth?s intentions for their own purposes in this opera, The Rake?s Progress

Corrosion of C-95, N-80, S13Cr Metal at HP/HT Conditions and the Effects of Viscoelastic Surfactants on Corrosion

In the oil and gas industry, corrosion damage during treatments often occurs due to the use of corrosive treatment fluids and can result in problems such as tubular or equipment failure, and leaking. These problems can incur high costs of maintenance and pose as safety hazards to workers on site. Hydrochloric acid (HCl) is a cheap and cost effective fluid that is commonly used in the oil and gas industry to dissolve scale and acidize formations. However, at high temperatures, it becomes extremely corrosive. Alternative acidizing fluids are typically used in place of HCl at these temperatures. However, in the event that HCl is required, corrosion inhibitors are added to the solution. In this work, the corrosion rates of two blends of HCl based acidizing fluids were tested on C-95, N-80, and S13Cr. The results show that the corrosion rate of the acidizing fluid is the lowest for N-80 metal under all conditions tested. An increase in corrosion rates for blend A tests as acid concentration increased was observed to be higher at 280°F than at 240°F despite a 1 vol% increase in corrosion inhibitor concentration to compensate for the increase in acid concentration. The increase in corrosion rates at 240°F ranged from 0% to 9% while the range increased to 17% to 36% at 280°F. Blend B showed significant reduction in protection for N-80 at 280°F when acid concentration was raised to 20 wt% with the change in corrosion rate increasing to 68.2% from 9.2% at 240°F. In addition, VES was shown to influence the corrosion rates of N-80 and S13Cr metal negatively. The absence of VES from blend B at 280°F showed a corrosion rate of 0.0216 lb/ft² and 0.0159 lb/ft² for S13Cr and N-80, respectively. These rates increased to 0.0253 lb/ft² and 0.0169 lb/ft² with 5% VES, and to 0.0264 lb/ft² and 0.0187 lb/ft² respectively when 8% VES was used. A green coloration of the post-corrosion solution was observed when blend A was used with S13Cr metal

Service encounter behaviour (SEB) in higher education : a Malaysian perspective

Nowadays, marketing activities of HE institutions are increasingly important as they operate within their competitive and regulated environment. HE institutions have borrowed service industrial concepts to focus on the services they provide to students. They need to identify and implement tools to further understanding of the issues that impact on students' experiences. Apart from, focussing specifically on the learning experience in the sense of formal learning (where most of the past research has concentrated on), studies have also shown that support services are just as important in influencing students' learning experience. Hence, one of the support services, programme administration (PA) has become increasingly important due to the diversity of programmes offered and it contributes to the learning experience of students as well as indirectly impacting upon institutions' competitiveness. In order to enhance the learning experience of students and to manage the service encounter between students and programme leaders (PLs), it is argued that there must be an understanding of the service encounter behaviour (SEB) of the interacting parties and more importantly from a dyadic perspective since a service encounter is a two-way interpretive process. Thus, this research is set in the HE context, focussing particularly in PA, exploring the SEB (the situational definition and situational roles) of student-PL from a dyadic perspective (from student's and employee's perspective) to improve the management of service encounters as well as to enhance the learning experience of students. The conceptual framework is based on Czepiel et al. (1985) concept of a service encounter emphasising that it is purposeful where tasks need to be completed within a set of rules constrained by the nature of service and the behaviour bounded by roles assumed by the interacting parties. To manage a service encounter, the SEB of the interacting parties needs to be understood and from a dyadic perspective paying attention to roles represented by each participant. This research has borrowed literature from the social psychology discipline i.e. Mead (1934) SI perspective of role and McHugh's (1968) situational definition to further understanding of the dynamism of interactions to gain further understanding of the SEB (role expectations and role response of the interacting parties). Taking the social constructionist epistemology, this research seeks to understand the meanings student- PL construct when interacting and how these meaning have led to specific SEB. By adopting the interpretivists' paradigm embedded in symbolic interactionism, the researcher tries to interpret the underlying meaning of students'-PLs' SEB from a dyadic perspective. Qualitative case study methodology is employed using the critical incident technique (CIT) as a method to elicit student-PL experiences in service encounters, helping them to focus on specific situations when recounting their SEB. To make sense of these data, narrative analysis is used to interpret the constructions of students¬PLs in their interactions. The study has included 42 participants (26 students and 16 PLs) from 4 private colleges in Malaysia. It has yielded 63 service encounters categorised into 11 types of service encounter, covering most of the situations where a student would approach their PLs in a typical semester. The findings have indicated that defining a service encounter is significant and is functional in shaping the situational roles to be represented, thereby influencing the outcome of the situation. It has shown that even though service encounters can be similar, different situational roles can lead to different outcomes. These key findings are evidenced in a SEB guide, giving a bundle of possible situational roles in identified service encounters. These outcomes have implications for students, PLs and the management as well as future research. This research has contributed by extending the SEB..