Multi-texture image segmentation

Visual perception of images is closely related to the recognition of the different texture areas within an image. Identifying the boundaries of these regions is an important step in image analysis and image understanding. This thesis presents supervised and unsupervised methods which allow an efficient segmentation of the texture regions within multi-texture images. The features used by the methods are based on a measure of the fractal dimension of surfaces in several directions, which allows the transformation of the image into a set of feature images, however no direct measurement of the fractal dimension is made. Using this set of features, supervised and unsupervised, statistical processing schemes are presented which produce low classification error rates. Natural texture images are examined with particular application to the analysis of sonar images of the seabed. A number of processes based on fractal models for texture synthesis are also presented. These are used to produce realistic images of natural textures, again with particular reference to sonar images of the seabed, and which show the importance of phase and directionality in our perception of texture. A further extension is shown to give possible uses for image coding and object identification

Bandwidth enhancement : correcting magnitude and phase distortion in wideband piezoelectric transducer systems

Acoustic ultrasonic measurements are widespread and commonly use transducers exhibiting resonant behaviour due to the piezoelectric nature of their active elements, being designed to give maximum sensitivity in the bandwidth of interest. We present a characterisation of such transducers that provides both magnitude and phase information describing the way in which the receiver responds to a surface displacement over its frequency range. Consequently, these devices work efficiently and linearly over only a very narrow band of their overall frequency range. In turn, this causes phase and magnitude distortion of linear signals. To correct for this distortion, we introduce a software technique, which considers only the input and the final output signals of the whole systemwhich is therefore generally applicable to any acoustic system. By correcting for the distortion of the magnitude and phase responses, we have ensured the signal seen at the receiver replicates the desired signal. We demonstrate a bandwidth extension on the received signal from 60-130 kHz at -6dB to 40-200 kHz at -1dB in a test system. The linear chirp signal we used to demonstrate this method showed the received signal to be almost identical to the desired linear chirp. Such systemcharacterisation will improve ultrasonic techniques when investigating material properties by maximising the accuracy of magnitude and phase estimations

Secondary technical schools in England and Wales : A study of administrative and curriculum policies

The impact of vocationalism on secondary education in England and Wales has been limited in range and incidence. This study examines some of the attempts to give expression to practical education in schools between 1889 and 1965. It focuses on institutions specifically charged with providing a technical education to pupils of secondary school age, with particular reference to Junior and Secondary Technical Schools. Collectively, the technical schools were casualties of policies which emphasized their instrumental nature, and which failed to secure their ambiguous institutional foundations. This impeded the projection of the educational benefits of vocationalism. Nor were curriculum policies clear about the favoured methods, content or disposition of secondary technical education. Practical education denoted an ambition rather than an agreed approach to secondary education. Administrative and curriculum policies lacked the coherence necessary if new ideas were to be presented successfully. These contentions are elucidated through an examination of central and local policies. These were determined by the interaction between administrative, professional, industrial and political interests. Reference is also made to some of the contemporary justifications of practical education. Enabling policies originated in the localities and found expression in a number of institutions. They were belatedly endorsed by the central department. In the process an 'ideal' type emerged, the 'Technical High School of Science'. It was intended to be the vocational counterpart of the academic grammar school. With its emphasis on scientific and technological concerns it represented one strand of practical education. Changes in science, technology and employment have meant that the curriculum of the technical schools no longer reflects contemporary needs. Their concern with practical education, however, remains undiminished. Their importance lies in the assistance they provide in posing questions about present day practices. The history of the technical schools underlines the need to define precisely the meaning of vocationalism. In the period under discussion, 'vocationalism' was the starting point for disagreements about the nature and purposes of practical education. 'Liberal' vs. 'Vocational'; 'Education' vs. 'Training' were standard formulations which left little room for synthesis. The case for vocationalism was un-coordinated . It was hindered by a disinclination to include curriculum issues alongside matters of provision. It was left to individuals, sectional groups, and sympathetic administrators who approached the subject from a multiplicity of viewpoints and institutional settings

Investigating the relationship between perfectionism and self-compassion: research protocol

Background: Perfectionism is a multidimensional personality trait characterised by high personal standards, self-critical evaluation and concern over mistakes (Frost, Marten, Lahart, & Rosenblate, 1990). Preliminary findings suggest that some forms of perfectionism are negatively correlated with self-compassion (Neff, 2003a), a mindset characterised by being moved by your own suffering and acknowledging that you are worthy of care and understanding (Brion, Leary, & Drabkin, 2014). However, there have been no further studies that investigate this relationship. Method: A combined perfectionism measure (79 items; Stoeber & Madigan, 2016) and the Self-Compassion Scale (26 items; Neff, 2003a) will be administered online. This study requires a sample of 400-500 participants. Analysis: Part I: Psychometric test construction via item reduction and factor analysis. Part II: Testing a structural equation model of the relationship between perfectionism and self-compassion. Discussion: This study will develop a new measure of perfectionism and provide new information about how perfectionism relates to self-compassion. Its findings have the potential to significantly impact therapeutic approaches to mental health and wellbeing

Biodiversity criteria and indicators for the sustainable management of industrial plantations.

Thesis (M.Env.Dev.)-University of Natal, Pietermaritzburg, 1999.Abstract not available

The Micro-Optical Ring Electrode:A Sensor for Multiple Actinide Ions

This thesis researches the development of the Micro-Optical Ring Electrode (MORE) for the analysis of trans-uranium elements in aqueous mixtures. The MORE is a photoelectrochemical device based on a ring microelectrode that uses the insulator interior to the ring as a light guide. This single device exploits the unique photophysical and electrochemical properties of multiple analytes present in mixtures to quantify them. This study aims to develop a protocol for the analysis of ions of uranium, neptunium and plutonium. These elements are most relevant to the nuclear industry, especially in the areas of decommissioning and fuel-reprocessing, where speedy and safe identification of radioactive contaminants is essential. Non-radioactive surrogates were used to test whether the MORE could generate photocurrents from ions with similar chemical properties to their radioactive counterparts. The results obtained by the successful generation of photocurrents were compared to the mathematical model proposed by (Andrieux, Boxall and O’Hare, 2006a). Depleted uranium was used as a surrogate for active uranium whilst nonradioactive surrogates vanadium and cerium was used for neptunium and plutonium. Upon successful detection of a photocurrent from the surrogates the optimum parameters to give the largest photocurrent magnitude possible were established. For uranium these parameters were an illumination wavelength of 410 nm, a working electrode potential of 0.7 V and the electron acceptor ethanol at a concentration of 200 mmol dm-3 . For vanadium these parameters were an illumination wavelength of 350 nm, a working electrode potential of 0.5 V and the electron acceptor iron (III) chloride at a concentration of 100 mmol dm-3. No photocurrents were generated for cerium. A preliminary study into the ability of the MORE to detect photocurrents generated by individual ions in a mixture of uranium and ruthenium was also carried out. The surface finish at the tip of the MORE was shown to influence the magnitude of the generated photocurrents with a rougher finish resulting in larger photocurrents

A multidimensional approach to perfectionism and self-compassion

Preliminary research suggests that maladaptive perfectionism impedes the development of self-compassion, a self-attitude with numerous biopsychosocial benefits (MacBeth and Gumley, 2012; Neff and Knox, 2017). The precise relationship between these constructs remains unclear, but if accurately modelled could foster an understanding of the barriers that perfectionists experience to being self-compassionate, enabling focused interventions to be developed. This general population study (N=428) used structural equation modelling to investigate how multidimensional perfectionism related to multidimensional self-compassion. The negative perfectionism dimensions of Concern over mistakes and Discrepancy significantly predicted lower levels of overall self-compassion and its positive dimensions of Self-kindness, Common humanity and Mindfulness. Findings were discussed in relation to the development of population-tailored, dual-focused, interventions aimed at reducing perfectionism and increasing self-compassion