8,265 research outputs found
A survey of some fifth- and sixth-formers' perceptions of mathematics
No full textThis Report gives some results of a small but purposive survey of the attitudes of school fifth- and sixth-formers to mathematics as a subject and their opinions as to whether they wished to proceed to further study of mathematics. The survey was conducted by direct face-to-face interviewing of the pupils at their schools during the academic year 1990-1991. The interviewing and the initial analysis of the data were carried out by a fourth-year student, Mr R T Davies, in the Department of Mathematics and Statistics at Brunel University as part of his Final Year Project. The author of this Report was closely involved with the work, as was Dr E J Davis of Henley Management College; both the author and Dr Davis had roles of project supervisors and independent roles concerning survey design and analysis
Irregular C2 surface construction using bi-polynomial rectangular patches
No full textThe construction of C2 surfaces using bi-polynomial
parametric rectangular patches is studied. In particular, the analy-
sis of the C2 continuity conditions for the case of n patches meeting at
an n-vertex is developed
Optimization techniques with knowledge based control in ship concept design
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.An integrated computational approach to Ship Concept Design using optimization techniques and a knowledge base to control the optimization process has been developed. The system automates both synthesis and analysis; analysis by the repeated sequential use of Design Theory Modules and synthesis through the optimization process, which compromises conflicting requirements, subject to constraints.
The intention of this work has been to find a better approach to automated design synthesis and at the same time employ detailed analytical tools such as a three-dimensional hull-form definition and engineering analysis modules.
Optimization techniques and a knowledge base are combined to achieve the desired capabilities, taking advantage of the benefits optimization can bring using goal oriented methods and exploratory searches, alongside a knowledge base that controls the synthesis process rather than the design. A function mapping strategy has been developed to provide a multiple-parametric view of regions of the optimization objective function and constraints. A discussion is included on the role of further applications of expert systems to design systems in both synthesis and analysis and their possible interference with creativity and innovation.
Two design examples are provided, one showing the application of the system using optimization and the other adding the use of the knowledge base. The results are compared and discussed.National Council of Research (CNPq - Brazil
Numerical computations of three dimensional thin panel structures using reissner's variational principle
No full textA finite element model for analysing static problems of three-dimensional thin panel constructions is presented. The potential energy of stretching of each panel is represented by the classical Reissner formulation of two-dimensional elasticity, and in the finite element discretisation piecewise constant stresses and piecewise linear u-, v- displacements are used. The potential energy of bending of each panel is represented in the finite element discretisation by Herrmann's model, i.e. piecewise constant moments and piecewise linear w - displacements. The physical appropriateness of the model is verified for different assemblages of panels, and in all cases good numerical results are obtained
A practice based learning environment for engineering students: Acquiring competencies for working on advanced manufacturing engineering
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.In this thesis the author describes the design and operation of a learning environment aimed at imparting technical, technological and managerial knowledge, developing understanding of the underlying issues and enhancing team work skills for an advanced technology future. He offers an analysis of learning, education and training and compares group work with individual tasks, presents a major case study and illustrates the features which distinguish the approach from role play, simulation and experiential learning. When staff at Brunel University were faced with the problem of teaching Computer Integrated Manufacturing (CIM) to engineering students on thin sandwich type undergraduate degree programmes the writer suggested the use of an approach he would later describe as 'practice based learning' or 'real life simulation'. The fourth year course in CIM is designed as a double option for the complementary undergraduate courses, Brunel Manufacturing Engineering (BME) and Special Engineering Programmes (SEP). It is an extension of the Manufacturing Design and Practice course in years one to three of the BME course and of the Design strand on SEP, both of which restrict students' work to the use of individual machine tools and stand alone computing facilities. A wide range of teaching methods is used on the CIM course, including lectures by course staff, presentations by experts and, as the major element, a large group project involving all the students on the course, organised in a management matrix, coordinated by the students and supported by the staff acting as experts. The students also undertake assignment work alongside the technical tasks, to focus their thinking and to improve written communication skills. While the course described cannot replace more than a small proportion of the more conventional lecture, laboratory and tutorial teaching on an engineering programme, it provides a setting where students can experiment and learn about their own strengths and weaknesses in a realistic situation and in the context of teamwork. It also offers a space where they can make quite serious mistakes without direct consequences to their careers. The experience of seven years leads the author to believe that advanced manufacturing technologies and the associated management techniques should be taught in a project based environment with clear and real targets and realistic constraints, offering students challenges to which they can only rise through close and creative team work. The management of task execution must be left largely in the students' own hands. A high level of "consultant" type support is essential though, allied to an assessment scheme which promises and ensures fair treatment of the individual. The different parts of the thesis will be relevant to readers depending on their interest and background. Chapter 1 sets the scene and outlines the approach taken. Following this broad outline of the scope of the dissertation the author places Computer Integrated Manufacturing in a wider context in chapter 2, by providing an introduction to the underlying issues of computer integration and human factors. He puts forward a case for new approaches to the education and training of engineers and managers who will be working in Computer Integrated Manufacturing and Advanced Manufacturing Environments in general. Chapter 3 is devoted to the management of projects while chapter 4 is used to question the role of the engineer. Chapters 5 and 6 provide an introduction to theories of knowledge, teaching, learning and motivation. Chapters 7 and 8 are devoted to particular aspects of engineering education, while chapter 9 reviews the approach used at Brunel University. The topical issues of competence and its relevance to engineering education is discussed in chapter 10, leading into chapters 11 and 12 which deal with aspects of the CIM course. Chapters 13 and 14 are devoted to case-studies and particular tools. The key question of assessment of a practice oriented and team based course is addressed in chapter 15, followed by an evaluation of the CIM process and its application to engineering education of a full time nature which is included in chapters 17 and 18.Funding was obtained from The General Electric Company Prize 1993: Manufacturing Systems Engineering
Physical dance performance: An investigation into the development of a performance technique based on the integration of certain Korean dance technique and contemporary Western styles of dance and physical theatre
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 04/10/2001.This development of a performer practice that integrates elements of traditional Korean dance technique and Western forms of physical theatre and contemporary dance is based on an approach to internal understanding and external execution. Central to the work is the concept of body energy, or Ki. This ancient Eastern term is translated into a contemporary practice that enables a performer to engage mental and physical training. Breath and the use of breath in performing are the principal means of achieving this level of engagement
Moment properties of estimators for an extreme value regression model with type 2 censoring
No full textAn extreme value regression model for grouped data with type 2
censoring is considered. The response variable is taken to have a
type 1 ext reme va lue d i s t r i b u t i on for sma l l e s t v a l ue s a nd a s tandar d
linear regression model is assumed f o r t he means . Large sampl e
approximations to the variances of the maximum likelihood estimators
are derived. The small sample moment properties of the maximum
likelihood estimators are evaluated by simulation for the case of
simp l e l i n e a r r e g ress i o n . T h e r e sul t s s h o w t h a t t h e e stima t or o f
the scale parameter has a s t rong bias in sma l l samples, particularly
when ther e is a heavy degree of censoring. Final l y , sma l l sample
variance and mean square error efficiences of the best linear unbiased
estimators relative to the maximum likelihood estimators are assessed
Statistical procedures based on exponential scores
No full textMany statistical models have been proposed in which underlying exponential
distributions are assumed. Applications of such models occur in a large number of areas, for example in reliability and life-testing investigations and in the study of the pattern of intervals between point events in a series of events when a Poisson process is often postulated. The methods of statistical inference for such models are usually simple to apply but unfortunately are sensitive to departures from the exponential form. In a significance testing situation this leads to a difficulty in interpretation since the true observed significance level may differ appreciably from that calculated on the assumption of an underlying exponential distribution, if the assumption is incorrect.
To overcome this drawback, distribution-free tests have been proposed in which the observations are first ranked and the ranks then replaced by exponential scores which are the expected values of the order statistics in a sample from the standard exponential distribution. This guarantees the validity of the test, whatever the form of the underlying distribution. In addition there is no loss of efficiency in very large samples when the underlying distributions are exponential, and often more generally, when the distributions belong to a Lehmann family which includes the Weibull distributions with common power parameter and hence the exponential distribution as a special case.
In this report, we describe a number of statistical tests based on exponential scores, some new, some well-known, many of which have been proposed and evaluated within the last ten years. The purpose of this is to demonstrate the wide area of application of exponential scores procedures. The procedures which are described deal with goodness of fit tests for the exponential distribution, the comparison of two samples with and without censoring, and the comparison of k>2 samples, and finally tests for trend and serial dependence alternatives against a renewal process for the intervals in a series of events. Some of the research findings related to powers of some of the tests are discussed, these findings being based on a series of investigations made by the author over the period 1975-1978
The mechanical behaviour of polyethylene pipe systems
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The design of polyethylene (PE) pipelines for
applications in the gas, water and chemical process industries has been based on data mainly obtained from stress rupture testing
pipes only. In practice, installations are composed of both extruded pipe and injection moulded fittings which are joined by a fusion welding technique and are very often
subjected to internal pressures of a fluctuating nature. Several makes of PE pipe systems were therefore obtained and work was undertaken to fully characterise mechanical
performance in terms of internal pressure loadings. Butt-welded test specimens comprising pipe lengths and fittings were subjected to both static and fluctuating
conditions at 80°C, at pressures resulting in brittle fractures (below the knee on stress rupture curves) and at frequencies not exceeding 7.5 cpm (0.125 Hz). Resulting fracture surfaces were examined to identify
sources of crack initiation and mechanisms of failure. Mechanical behaviour of the PE pipe samples was found to be markedly influenced by the grade of plastics compound,
the pipe system dimensions, mould designs and methods of processing. Fatigue loading was the most aggressive test method and significant reductions in lifetimes were
observed in fittings or joints between pipes and fittings with only modest increases in the frequency of pressurisation. It was also demonstrated that improved stress rupture
behaviour did not necessarily lead to better fatigue performance. For the square-wave loading profiles used, an idea of the relevant failure mechanisms in any given system was obtained by comparing experimental Nf values with those predicted from cumulative damage principles based on
Nf=τSR/τmax. In all types of system, failure was initiated at a defect residual from processing or jointing. Over 95% of all small diameter pipe fractures originated from inclusions at or close to the inside wall. They were geometrically and elementally analysed and suggestions made as to their possible origin and means of elimination. For one PE a reasonable correlation was obtained, between lifetime under stress rupture or fatigue and the inclusion size as measured in the fracture plane.Science and Engineering Research Counci
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