A multi-purpose method for analysis of spur gear tooth loading

A large digitized approach was developed for the static and dynamic load analysis of spur gearing. An iterative procedure was used to calculate directly the "variable-variable" gear mesh stiffness as a function of transmitted load, gear tooth profile errors, gear tooth deflections and gear hub torsional deformation, and position of contacting profile points. The developed approach can be used to analyze the loads, Hertz stresses, and PV for the normal and high contrast ratio gearing, presently the modeling is limited to the condition that for a given gear all teeth have identical spacing and profiles (with or without surface imperfections). Certain types of simulated sinusoidal profile errors and pitting can cause interruptions of the gear mesh stiffness function and, thus, increase the dynamic loads in spur gearing. In addition, a finite element stress and mesh subprogram was developed for future introduction into the main program for calculating the gear tooth bending stresses under dynamic loads

A critical evaluation of teaching practice in geography in Egypt

The central problem of this research is 'How the supervision and assessment process for the geography student-teachers in Egypt can he improved?’. This problem is of high significance for a number of reasons : First there is a lack of clear criteria for the assessment of the geography students. Secondly, college students themselves have no handbook to guide their performance. Thirdly, the problem becomes more acute when the number of students reaches several thousands, while the number of experienced supervisors does not increase accordingly. The research is sub-divided into several areas : a) a review of the related literature; b) an assessment of the range of influences which have shaped the development of teacher education in Egypt and the emergence of a system of teaching practice as an integral component of that educational process; c) an evaluation of the de facto status of teaching practice in the El Sharkia Governorate as a case study; d) an assessment of current practices of supervision and assessment of geography students in England and Wales; e) the formulation of a more appropriate framework for supervision and schedule for assessment for use in the Egyptian context and f) an improvement in the entire system by which student-teachers of geography are supervised and assessed in teaching, practice and making recommendations for further lines of research. The results of this research will contribute to the development of the geography teacher preparation and training in particular and to the education of Egypt in general

A study of geo-chemical problems by gas-analytical methods

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Reading strategies and learning outcomes

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The project was concerned with action research aimed at improving the range and effectiveness of reading-to-learn. Students (Advanced Level and Undergraduates) report reading-to-learn problems but they are only vaguely aware of the cognitive organisation (intuitive tactics and strategy) which underlies and structures their reading behaviour. The research emphasis was therefore primarily learner oriented. 2. This approach clarified such issues as: (i) Learner interpretation of instructional directives to learn for specific tasks. (ii) Learner methods of translating the task definition into an operational plan for reading. (iii) The systematic relationship between the tactics and strategies of reading (the time-structure of reading behaviour), and the variety of reading outcomes, within sentence, paragraph and chapter sized texts. (iv) Training procedures (incorporating feedback of performance) by which a student can explore now tactics of reading-for-learning. 3. This approach has required the development of three now techniques: a) A method for recording reading behaviour. b) A method by which the ‘structure of a text’ can be systematically described. c) A system of training procedures for encouraging students to develop more effective methods of reading-for-learning. 4. The empirical data showed that there were two related aspects in developing more effective reading-for-learning; the first was to develop a clearer definition of instructional directives and the second was the ability to translate these into effective operational plans. As a result of individual differences in cognitive structure and skill, students differ in their operational task definition in relation to specific learning outcomes. The plans of a 'beginner' or an 'expert' may bring about the same outcome but they differ considerably. Students also differ in their training needs within a training procedure for reading-to-learn effectively. This emphasises the need to level a hierarchically organised learner-controlled programme of self-diagnosis and training. 5. The theoretical outcome of the research was a tentative model of the student learning by reading. This model is based on the concept of a dynamic interaction between the learner's cognitive structure and skill, the learner's task definition and how this becomes operational, and the syntactic and semantic structure of the text. The model can be considered as a hierarchically organised multi-level description of the reading process. The reading strategy formed of the tactics and the learning outcome, represent the observables of this interaction. The model was influenced by the theories of J. Bruner, G. Miller, N. Chomsky and R. Gagné. 6. The research was directed towards the identification of strategies and outcomes of reading-to-learn, with the double aim of investigating these areas and training students to increase their skill; both these aims were in line with endeavours to increase self-organisation and individual autonomy in learning. 7. Whilst the goals of the research were largely achieved, the results have illuminated a number of practical and theoretical issues that need further investigation.Social Science Research Counci

The influence of beer physical stabilisers on beer flavour stability

Beer contains proteins and polyphenols that are known to be responsible for undesirable haze formation. In this work, haze forming compounds were monitored and the effects of their removal on flavour stability were examined. The main aim of this research was to confirm or deny the influence of physical stabilisation on beer flavour. Beer was made in the university pilot brewery with a pale malt to 5% ABV and 25 International Bitterness Units. Physical stabilisers commonly used in beer stability treatments (i.e., Chill Garde™, Lucilite XLC™ and TR™, Polyvinylpolypyrrolidone and tannic acid) were added to a beer at manufacturers recommended amounts (i.e., high, medium and low levels). The beer was aged up to 11 weeks. Numerous analytical examinations were undertaken including pH, alcohol, tannoid and proteins levels, foam stability, haze, total polyphenol levels, iron copper and manganese levels, electron spin resonance t150 values, bitterness, total and free SO2 levels, polyphenol species, volatile esters, higher alcohols, acetaldehyde and total vicinal diketone levels. After extensive sensory training, panellists were used to evaluate beer sensory attributes. The analytical results of flavour compounds were immediately compared to sensory testing. Sensory profiling and the ‘two out of five’ difference test were employed to evaluate beer flavour. The sensory profiles of all stabilised beers were also compared to unstabilised control using spider plots. Linear regression was used to correlate the results from analytical measurement to sensory data. Sensory differences between stabilised and unstabilised samples were not found. Neither the trained sensory panels were not capable to recognise differences using two out of five test. The effectiveness of each physical stabiliser on haze and flavour was presented and discussed. As a result of this work it can be argued that the removal of haze active polyphenols nor removal of the haze-active proteins substantially influence beer flavour. This work has gathered enough data to compare the stabilisers and decide on their effectiveness. The most effective beer stabilising agent was PVPP, it worked at the lowest dose (5g/hl) efficiently improving haze stability and yet it did not influence flavour stability. The other stabiliser presented in literature as the effective polyphenol removal agent did not remove polyphenols at low dosing level, it was only effective at high concentration, the influence on flavour was not proved either, however the use of such stabiliser would not be economic for the brewer. Interesting for the future research would be to study in detail the stabiliser Chill Garde to be able to answer why it also removes polyphenols and whether its use could replace the actual practice of breweries that is the combined stabilisation. Chill Garde removes haze active proteins but in great extent it also removes all of the haze active polyphenols. This fact was not described in literature nor in the data sheets for this products. Much of the data obtained in this work was used to track changes in flavour during ageing, no forced ageing was used, and this data was used to enrich the Dalgliesh model of beer ageing and track the changes in beer sensory during a period of 11 months

Statistical Modelling and Inference in Image Analysis

The aim of the thesis is to investigate classes of model-based approaches to statistical image analysis. We explored the properties of models and examined the problem of parameter estimation from the original image data and, in particular, from noisy versions of the the scene. We concentrated on Markov random field (MRF) models, Markov mesh random field (MMRF) models and Multi-dimensional Markov chain (MDMC) models. In Chapter 2, for the one-dimensional version of Markov random fields, we developed a recursive technique which enables us to achieve maximum likelihood estimation for the underlying parameter and to carry out the EM algorithm for parameter estimation when only noisy data are available. This technique also enables us, in just a single pass, to generate a sample from a one-dimensional Markov random field. Although, unfortunately, this technique cannot be extended to two- or multi-dimensional models, it was applied to many cases in this thesis. Since, for two-dimensional Markov random fields, the density of each row (column), conditionally on all other rows (columns) is of the form of a one-dimensional Markov random field, and since the distribution of the original image, conditionally on the noisy version of data, is still a Markov random field, the technique can be used on different forms of conditional density of one row (column). In Chapter 3, therefore, we developed the line-relaxation method for simulating MRFs and maximum line pseudo-likelihood estimation of parameter(s), and in Chapter 5, we developed a simultaneous procedure of parameter estimation and restoration, in which line pseudo-likelihood and a modified EM algorithm were used. The first part of Chapter 3 and Chapter 4 concentrate on inference for two-dimensional MRFs. We obtained a matrix expression for partition functins for general models, and a more explicit form for a multi-colour Ising model, and thus located the positions of critical points of this multi-colour model. We examined the asymptotic properties of an asymmetric, two-colour Ising model. For general models, in Chapter 4, we explored asymptotic properties under an "independence" or a "near independence" condition, and then developed the approach of maximum approximate-likelihood estimation. For three-dimensional MMRF models, in chapter 6, a generalization of Devijver's F-G-H algorithm is developed for restoration. In Chapter 7, the recursive technique was again used to introduce MDMC models, which form a natural extension of a Markov chain. By suitable choice of model parameters, textures can be generated that are similar to those simulated from MRFs, but the simulation procedure is computationally much more economical. The recursive technique also enables us to maximize the likelihood function of the model. For all three sorts of prior random field models considered in this thesis, we developed a simultaneous procedure for parameter estimation and image restoration, when only noisy data are available. The currently restored image was used, together with noisy data, in modified versions of the EM algorithm. In simulation studies, quite good results were obtained, in terms of estimation of parameters in both the original model and, particularly, in the noise model, and in terms of restoration

Orbit transfer vehicle advanced expander cycle engine point design study. Volume 2: Study results

The design characteristics of the baseline engine configuration of the advanced expander cycle engine are described. Several aspects of engine optimization are considered which directly impact the design of the baseline thrust chamber. Four major areas of the power cycle optimization are emphasized: main turbine arrangement; cycle engine source; high pressure pump design; and boost pump drive

Sorption by porous solids

A number of isothermals have been determined for the sorption of the vapours of amino compounds on silica and ferric oxide gels. The sorbates studied include the normal aliphatic amines, from ethylamine to n-heptylamine, t-butylamine, ethylene diamine, cyclohexylamine and pyridine. Data for ethyl alcohol and water is also included, for comparative purposes. A standard 'gravimetric' technique has been used in every case, except that of ethylamine, for which a new technique has been developed. The ferric oxide isothermals all contain a large. hysteresis loop, the size of which does not vary with increasing molecular diameter. Silica gel B2 isothermals show a large loop with water, and small loops with ethyl alcohol, n-propylamine and ethylene diamine. Larger molecules give completely reversible isothermals. This data confirms the most important prediction of the 'open-pore' theory of capillary condensation. Reference is made to data in the literature which provides further confirmation of this prediction. Silica gel C and silica gel D systems both contain large hysteresis loops. Only a few results are quoted for the former system, as the isothermals obtained were not reproducible. Where possible, the Kelvin equation has been used to estimate the most frequent occurring pore space available for capillary condensation. In some cases an estimate of the true pore radius has been made, by correcting for the thickness of the adsorbed layer. Evidence is presented for orientation of sorbate molecules in the first layer on ferric oxide gel, and, to some extent, on silica gel D. The volumes adsorbed at saturation obey Gurwitsch Rule in every case. Ethylene diamine has been shown to have a lower freezing point in the adsorbed state than in the bulk state. The vapour pressures and surface tensions of some of the sorbates have been determined, using methods suitable for hygroscopic liquids.<p