This thesis is concerned with the fabrication, assessment and application of doped silica waveguides using Flame Hydrolysis Deposition. Deposition apparatus has been designed and constructed. This equipment consists of a gas supply assembly, a bubbler cabinet, a deposition box and a chemical scrubber. An optimum sintering regime for the low density silica soot has been established consisting of 60 minutes at 1250oC. This regime is dependent on the levels of P2O5, GeO2 and/or TiO2 doping in the silica host. Independent control of layer thickness and index is achieved. Refractive index can be varied by changing the doping levels, and thickness, by increasing the number of traversals of the hydrolysing flame. Film homogeneity in terms of layer thickness was found to be difficult to control and up to 30% variation in thickness was obtained in some samples. Thermophoretic effects were shown to play an important part in the deposition process. Titanium and phosphorus doped films were found to suffer film degradation and aging. This led to the formation of titanium rich crystals and crystal agglomerates which produced Rayleigh/ Mie scatter in the sintered films. No such problem was found with Germanium, and all films were subsequently fabricated using Germanium and Phosphorus. No out-of-plane scatter was observed in the sintered films. Ridge waveguides were fabricated using lithography and Reactive Ion Etching in a CHF3 plasma, giving waveguides with smooth side walls. Loss assessment was carried out using two techniques, both of which were non-destructive. One involved a video camera to scan across the waveguide and detect the out-of-plane scatter. This technique was sensitive to scattering centres and was less accurate for short lengths of guide. Loss figure varied from 0.2 to over 5 dB/cm depending on the scan length. The second technique involved turning the waveguide into a Fabry-Perot resonator, by coating the end faces of the waveguide. Temperature induced cycles in the output intensity could be used to obtain the waveguide attenuation. This technique was sensitive to the facet angles of the guides which could contribute significantly to the loss measured. Such resonances were obtained in only one sample and gave a loss figure of over 9 dB/cm which is considered unreliable. Films were doped with both Nd3+ and Er3+ using a solution doping technique and fluorescence spectra were obtained for both. Increased scatter was observed in the planar films with such doping. Holographic gratings were fabricated on planar waveguides with a view to their incorporation as feedback elements in a laser structure. Second Harmonic Generation was observed for the first time in planar rib waveguide structures doped with Phosphorus and Germanium. In a `seeding' experiment where 1064nm radiation was launched at the same time as a second harmonic `seed', a two-hundred fold increase was observed in generated second harmonic signal over the background level.

The object of this Ph.D. project was to design and construct an in-process, non contact surface finish sensor for high quality components generated using diamond turning. For this application the instrument must have the following properties: i rapid acquisition of data. ii capability of measuring translating and or rotating surfaces. iii ruggedness for in-process use. iv insensitivity to moderate vibrations. v remoteness from the surfaces to be measured. The remoteness requirement virtually excludes the otherwise ubiquitous stylus instrument, while the rapid gathering of data from rotating surfaces excludes other profiling techniques. The above mentioned properties strongly suggest an optical method. An optical diffraction technique has been chosen, since it produces an optical Fourier Transform of the surface. This transform is produced at the speed of light, since the optical system has the property of parallel data processing, unlike a typical electronic computer. With the aid of a microprocessor various surface finish parameters can be extracted from the optical transform. These parameters are respectively the rms surface roughness, slope and wavelength. The actual sensor consists of a measuring head and a minicomputer. It fulfils the above mentioned requirements. Its only limitations are: i limited to surface finishes up to 100nm ii presence of cutting fluids has to be avoided, although certain modern lubricating fluids can be tolerated. The algorithms devised to extract the surface finish parameters from the optical transforms have initially been tested on optical spectra produced by Thwaite. Comparison of the optical roughness values and the values quoted by Thwaite show close agreement. Thwaite's values are obtained by a stylus instrument. Rqopt (um) Rqstylus (um) 0.16 0.156 0.38 0.37 0.44 0.40 In addition a computer program has been devised which simulates the optical sensor head. The input data can be obtained by a profiling instrument, or generated by a computer program. This last option enables the creation of surface profiles with "controllable" machining errors. This program can be utilised to create an atlas, which maps optical diffraction patterns versus machine-tool errors.

The extraction of meaningful features from an image forms an important area of image analysis. It enables the task of understanding visual information to be implemented in a coherent and well defined manner. However, although many of the traditional approaches to feature extraction have proved to be successful in specific areas, recent work has suggested that they do not provide sufficient generality when dealing with complex analysis problems such as those presented by natural images. This thesis considers the problem of deriving an image description which could form the basis of a more general approach to feature extraction. It is argued that an essential property of such a description is that it should have locality in both the spatial domain and in some classification space over a range of scales. Using the 2-d Fourier domain as a classification space, a number of image transforms that might provide the required description are investigated. These include combined representations such as a 2-d version of the short-time Fourier transform (STFT), and multiscale or pyramid representations such as the wavelet transform. However, it is shown that these are limited in their ability to provide sufficient locality in both domains and as such do not fulfill the requirement for generality. To overcome this limitation, an alternative approach is proposed in the form of the multiresolution Fourier transform (MFT). This has a hierarchical structure in which the outermost levels are the image and its discrete Fourier transform (DFT), whilst the intermediate levels are combined representations in space and spatial frequency. These levels are defined to be optimal in terms of locality and their resolution is such that within the transform as a whole there is a uniform variation in resolution between the spatial domain and the spatial frequency domain. This ensures that locality is provided in both domains over a range of scales. The MFT is also invertible and amenable to efficient computation via familiar signal processing techniques. Examples and experiments illustrating its properties are presented. The problem of extracting local image features such as lines and edges is then considered. A multiresolution image model based on these features is defined and it is shown that the MET provides an effective tool for estimating its parameters.. The model is also suitable for representing curves and a curve extraction algorithm is described. The results presented for synthetic and natural images compare favourably with existing methods. Furthermore, when coupled with the previous work in this area, they demonstrate that the MFT has the potential to provide a basis for the solution of general image analysis problems.

In the first sub-section of the thesis, signal design for both linear and nonlinear system identification is considered. To identify a linear system using a perturbation test, a binary signal is sufficient and has the advantage of maximising the power available within a specified peak-to-peak amplitude. For this purpose, a program was written to generate five classes of binary and near-binary signal. However, to identify a nonlinear system with a Hammerstein structure, a multi-level signal is required, and methods to optimise such a signal are proposed. In the second sub-section, the detection of the departure from linearity for direction dependent processes is considered. It was found that only signals based on maximum length sequences allow the detection of such characteristics due to the coherent patterns formed in the cross correlation function. The 'combined' linear dynamics of the system are identified. The modelling of such processes using Wiener and neural network models is investigated. Practical results from an electronic nose are presented. The control of direction-dependent processes using the PID controller is then examined, with the design rules set according to the identified 'combined' dynamics. The thesis then moves on to the topic of autotuning. The autotuning of Smith predictors for processes with significant dead time is considered. The frequency response of the process is identified in closed-loop using a multi sine signal. Tuning rules for robust control are suggested which relate the controller parameters to the process parameters. A real application using a hot-air flow device is illustrated. The final sub-section of the thesis looks at the identification of Wiener-Hammerstein models. A new technique using linear interpolation is proposed which is based on the symmetry properties of the Volterra kernel. This method has the advantages that only a single experiment is needed, and it is simple to use since no optimisation or recursive computations are required. Simulation examples are provided to illustrate the effectiveness of the technique, and its robustness in the presence of noise and input signal distortion.

Two aspects of the behaviour of uncased composite 'T' beams of steel and concrete are considered. Flexural cracking in the reinforced concrete slab was studied by subjecting seven 350-mm deep composite beams to hogging bending moment. Measured strains were found to exceed those calculated from an elastic analysis ignoring concrete in tension. Also, the first cracks to form in the slab were much wider than expected. Both of these effects are shown to be due to drying shrinkage in the slab of the composite beam. A formula for calculating the mean surface strain in the slab, which allows for both drying shrinkage and tension stiffening, is proposed. Consideration of the parameters which affect cracking leads to a formula for predicting crack widths in composite beams. Comparison with experimental results shows that it is sufficiently accurate for design purposes. In a second series of tests, three 900-mm deep composite plate girders with slender webs were subjected to combined shear and bending to study their ultimate load behaviour. Failure was due to the formation of a plastic collapse mechanism which closely resembles that observed in plain steel girders under similar loading. The addition of a concrete slab acting compositely with the girder increased the ultimate strength of the beam, but variations in the size of the slab and the strength of the shear connection had negligible effect on the beam's strength. An idealised collapse model, based on the experimental observations, is described and is used in the development of a method to calculate the ultimate strength of composite plate girders. It is shown that a design method for plain steel girders in the draft Part 3, BS5400 may, with small modifications, be applied to composite plate girders.

This thesis describes a variety of experiments, many using advanced signal processing techniques, and electromagnetic acoustic transducers (EMATs). The first sections of this thesis describe the application of the pulse-compression signal processing technique with EMATs. This has been shown to improve the signal-to-noise ratio without the use of high levels of signal averaging, and thus potentially increases the speed of measurements. Ultrasonics thickness measurements and imaging were carried out to show that pulse-compression can be applied to the testing of the metals. The work was extended to demonstrate the successful measurement of fill level in drinks cans, and the detection of foreign bodies using fan-beam tomographic imaging in the drink cans. This thesis also describes the application of a continuous wavelet transform (CWT) to EMATs. The technique was applied to experimental EMAT data in thin metal plates, to identify propagation of s0, a0, a1, S1 and S2 modes in an aluminium plate from one waveform. To illustrate the usefulness of the approach, the extracted multiple modes were applied to tomographic reconstructions of artificial defects in plates. This thesis also describes metal texture measurements using EMATs and wavelet processing. The work described in this section focuses on the multi-scale discrete wavelet method where the analysis in time and in wavelet scale is discrete as opposed to the CWT. The use of discrete wavelet processing for signal analysis can improve the performance of EMATs data in highly noisy environments. Another section describes the use of the micro-stereolithography (MSL) process to fabricate EMATs, and this is followed by a description of the Synthetic Aperture Focussing Technique (SAFT) algorithm used to reconstruct images of data obtained from these EMATs. Finally, results are given, demonstrating that the EMA Ts can be used to perform NDE inspections. The thesis also contains conclusions and suggestions for further work.

The current state of activities in the design and manufacturing industry is marked by the various CAD/CAM/CAE systems which exist as islands of automation, and are used by engineers and designers in a non-integrated and ill-structured way. Thus the design problem is examined from separate and different perspectives, rather than as a whole. The goal of this research, is to develop a comprehensive, integrated and generic design system, that will ensure the realisation of concurrent engineering in practice. To this end, Design Function Deployment (DFD) has been developed. DFD enables the capture of customers' requirements, the establishment of design specifications and constraints in a solution neutral form, the generation of conceptual designs (architectures), the development of detailed designs layouts), the selection of materials and associated manufacturing processes and the development of suitable production plans. The generated design solutions are optimised against a composite set of multi-criteria (attributes) in a concurrent manner for key factors such as performance, robustness and cost as well as other life cycle issues (manufacture, assembly, serviceability, reliability, environment, etc) in order to choose the most satisfying design. DFD provides a recipe of design methods to support the designer or design team at any stage of the design process. The optimisation process involves the use of these supporting design tools (methods) encapsulated within it. DFD also provides an integrated product modelling environment which integrates both textual and geometric design information, and enables the capture of other design information related to design intent, rationale and history. The research that led to the evolution and development of DFD involved (a) a detailed investigation and research on Quality Function Deployment, QFD, a technique well suited for capturing and translating customer requirements into design specifications, (b) an extensive review of design philosophies, models, methods and systems and (c) an extensive investigation into concurrent engineering. The findings of this research has led to the development of the structure of the DFD system, which incorporates (1) a prescriptive design model, (2) a suite of design methods and (3) supporting knowledge/rulebases and databases, which are used for the generation of the design solution space and the optimal selection of the most satisfying design for subsequent implementation.

Liquid crystal techniques, combined with sophisticated software in increasingly powerful personal computers, are now permitting fairly comprehensive full-field studies of velocity, temperature and heat transfer coefficent-distributions, with their accompanying automatic analysis. Liquid crystals and true-colour image processing have opened some new approaches for heat transfer research and offer satisfactory accuracy and resolution. New and more incisive experiments are being designed for conventional situations, and other problems can now be studied which were previously not practical to consider. The history of these techniques is reviewed and the principal methods are described using illustrative examples from the literature and work of the author. A new liquid crystal thermometry method is described to determine quantitatively two-dimensional temperature distributions on a surface and in a fluid, from colour records obtained using a thermosensitive chiral-nematic material combined with image processing. Application type experiments have been carried out both to visualise the complex distribution of temperature and local heat transfer coefficient over a cooled surface disturbed by different solid obstacles, and also to investigate temperature and flow patterns in a rectangular cavity for natural convection. A new experimental method (optical and non-invasive) has been established to measure simultaneously both flow and thermal fields - this method may be described as particle image velocimetry and thermometry (PIVT). Some of the experimental results presented are applied to an important Industrial improvement in heat exchanger design and could result in substantial reductions in energy costs.

The gravimetric hygrometer of the UK National Physical Laboratory (NPL) provides a first-principles realisation of mixing ratio - the most fundamental measure of the humidity of a gas. The operation of the NPL gravimetric hygrometer has been validated to demonstrate its satisfactory performance as a primary standard for humidity within the UK national measurement system. The measurement performance of the gravimetric hygrometer has been characterised for mixing ratios within the range 0.01 g kg to 155 g kg 4 (equivalent at atmospheric pressure to a dew-point range of -60 °C to +60 °C). The significant aspects of the measurement have been assessed in detail; these being the balances and weighing processes, the efficiency of collecting water and dry gas, and the effects of stray water in the instrument. Sources of systematic error have been identified and their effects quantified. Wherever possible, such errors have been eliminated or reduced. Elsewhere, numerical corrections have been evaluated and applied to the results of measurements. The overall uncertainty of measurement for the gravimetric hygrometer has been estimated by evaluating the uncertainties contributed by each aspect of the measurement, and combining these statistically to find the overall effect. The estimated uncertainty at a level of confidence of approximately 95% (a coverage factor of k=2) was found to range between 0.015 percent of value at the highest humidity considered, near 155 g kg 1, and 1.27 percent of value at the lower limit of 0.01 g kg1. The gravimetric hygrometer has been intercompared with the humidity generator which is the NFL standard for dew point, using nitrogen as the carrier gas in these measurements. For the conversion between values of dew point and mixing ratio, the uncertainties in the reference functions have been reviewed for the vapour pressure curve of water, and for the water vapour enhancement factor which accounts for the non-ideal behaviour of humid gases. A new calculation of the enhancement factor for nitrogen is presented. The uncertainties due to sampling were also evaluated. On average, the uncertainties due to the reference functions and those due to sampling were found to comparable with the uncertainty in the gravimetric measurements. Taking all these into account, the intercomparison measurements agreed to within the combined uncertainties of the two instruments.

This report, in its earlier part, reviews some important aspects of research and development in the design of reinforced concrete members against shear. This review includes a study of the background of design method for shear resistance given in the British Standard code of practice and a comparison of this method with the methods recommended by the Eurocode and the American code of practice for concrete structures. Based on this study, the contributions to shear resistance of a member afforded by concrete, the tension steel and the links are identified. The influence of these constituents on the modes of transfer of shear has been investigated, in order to examine the method for estimating the overall shear resistance of the member. A test programme is reported, concerning horizontal steel at the centre of the cross-section as an alternative form of shear reinforcement. Tests on some fifty beam specimens were carried out, allowing for variation in the main parameters; for example, the span of beams, the strength of concrete and the amount of tension steel. Also, some beams did not have any shear reinforcement and some were provided with central bars, some with links and some with the combination of central bar and links. A design method has been derived on the basis of these tests, for estimating the contribution of central steel to the shear resistance of beams. This method has been verified with the help of measurement of stresses in the web steel, using strain gauges fixed on the reinforcement of two of the test beams. A similar design method is proposed for using central steel to enhance the punching shear resistance of slabs, based on the results of tests on fifteen slab specimens, allowing for variations in thickness of slabs, the strength of concrete and the amount of central steel. The design methods for beams and slabs have been examined with the help of a finite element computer program capable of using the non-linear properties of structural materials. Finally, the normal temperature design rules for beams have been modified and a method is proposed for design of beams exposed to high temperatures. This method has been verified on the basis of fire exposure tests on ten beam specimens provided with differing amount and type of web steel and with gauges for measurement of temperatures inside, the beams.