Evolutionary approaches to optimisation in rough machining

This thesis concerns the use of Evolutionary Computation to optimise the sequence and selection of tools and machining parameters in rough milling applications. These processes are not automated in current Computer-Aided Manufacturing (CAM) software and this work, undertaken in collaboration with an industrial partner, aims to address this. Related research has mainly approached tool sequence optimisation using only a single tool type, and machining parameter optimisation of a single-tool sequence. In a real world industrial setting, tools with different geometrical profiles are commonly used in combination on rough machining tasks in order to produce components with complex sculptured surfaces. This work introduces a new representation scheme and search operators to support the use of the three most commonly used tool types: end mill, ball nose and toroidal. Using these operators, single-objective metaheuristic algorithms are shown to find near-optimal solutions, while surveying only a small number of tool sequences. For the first time, a multi-objective approach is taken to tool sequence optimisation. The process of ‘multi objectivisation’ is shown to offer two benefits: escaping local optima on deceptive multimodal search spaces and providing a selection of tool sequence alternatives to a machinist. The multi-objective approach is also used to produce a varied set of near-Pareto optimal solutions, offering different trade-offs between total machining time and total tooling costs, simultaneously optimising tool sequences and the cutting speeds of individual tools. A challenge for using computationally expensive CAM software, important for real world machining, is the time cost of evaluations. An asynchronous parallel evolutionary optimisation system is presented that can provide a significant speed up, even in the presence of heterogeneous evaluation times produced by variable length tool sequences. This system uses a distributed network of processors that could be easily and inexpensively implemented on existing commercial hardware, and accessible to even small workshops

Theoretical framework for real time sub-micron depth monitoring using quantum inline coherent imaging

Inline Coherent Imaging (ICI) is a reliable method for real-time monitoring of various laser processes, including keyhole welding, additive manufacturing, and micromachining. However, the axial resolution is limited to greater than 2 {\mu}m making ICI unsuitable for monitoring submicron processes. Advancements in Quantum Optical Coherence Tomography (QOCT), which uses a Hong-Ou-Mandel (HOM) interferometer, has the potential to address this issue by achieving better than 1 {\mu}m depth resolution. While time-resolved QOCT is slow, Fourier domain QOCT (FD-QOCT) overcomes this limitation, enabling submicron scale real-time process monitoring. Here we review the fundamentals of FD-QOCT and QOCT and propose a Quantum Inline Coherent Imaging system based on FD-QOCT. Using frequency entangled sources available today the system has a theoretical resolution of 0.17 microns, making it suitable for submicron real-time process monitoring.Comment: 12 pages, 8 figure

An Appraisal of the Evidence Behind the use of the CHRODIS Plus Initiative for Chronic Pain : a Scoping Review

This work was supported by The Royal College of Physicians (Wolfson Foundation Intercalated Award to R.L.). The sponsor had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

KINEMATICS OF WOMEN'S SPRINT CANOEING TECHNIQUE

Little is known about the biomechanics of sprint canoeing, especially for women's canoeing, and a quantitative kinematic description of the motion would help coaches to develop valid technique coaching models. Five highly-trained female canoeists were filmed at 150 Hz while undertaking a 50 s maximal effort on a canoe ergometer, whose trolley motions were taken to represent those of the boat. Selected boat, body and paddle kinematics were evaluated at three key stroke cyde events (Contact, Paddle Vertical, and End of Drive) and their patterns monitored across the stroke cycle. While no clear trends between the kinematics and power output emerged, a range of strategies were identified and the data represent an initial step in the construction of detailed technique models that can be used to evaluate and monitor individual athletes

The relationship between praise poetry and poetry in Zulu and Xhosa

This study deals with traditional, oral praise poetry and modern, written poetry in Zulu and Xhosa. Previous contradictory and confusing research findings are reassessed. The theoretical nature of poetry and conditions for its composition are examined. The development of praise poetry as an oral genre and previous hypotheses concerning this development are reviewed. The widespread incidence of praise poetry in Africa and the extensive exposure of children to ukubonga (praising) is traced. Tentative hypotheses are posed concerning the developmental sequence of ukubonga from the coining of a praise name, to the fashioning of unpolished praise images until finally, a fully-fledged praise poem is composed. The structural development of Zulu and Xhosa _....... - ---·- .. ··----- c lan praises and the origins of modern Nguni poetry are shown. The profound impact on modern poetry by missionaries and Christianity, the "/ pervasive traditional izibongo (praise poetry) as well as the European // and Western poetic~nfluence is set out. l1iscellaneous general theories on the structure of Nguni poetry and the £ requent incidence of repetition are commented on. The nature, extent a nd efficacy of various types of imagery such as simile, p ersonification, metaphor and symbolism in Nguni poetry is studie d. The seemingly facile and obvious difference between traditional and modern ~ guni poetry; that is, between oral and written poetry, is shown to be somewhat blurred due to the reduction of much oral poetry to writing. :rhe study highlights the urgent need for further research because the III oral art is i ncreaJ i ngly falling into disuse due to the inroads of Westernization anY urbanization. The composition of poetry on themes drawn from a new, technologically advanced society and the experimentation with Western literary techniques such as rhyme schemes, is shown. The recent poetic genius of Vilakazi, a modern poet, as well as the originality of traditional poetry conclusion reached is that the best modern is a s s essed and the general poetry £ Nguni is that which is a symbiosis of traditional and modern, representing a continuum from the traditional genre of izibongo.African Language

Stonehenge excavations 2008

The following paper is the first published account of an excavation that took place at Stonehenge during April 2008. As this was the first excavation to take place within the stone circle for some forty years, the excavation has attracted an uncommon degree of interest, hence its publication in the Antiquaries Journal as an interim account of work in progress, in the form of an edited transcript of a paper first given at the Ordinary Meeting of the Society of Antiquaries of London on 9 October 2008. The paper explains that the 2008 excavation set out to date the construction of the Double Bluestone Circle at Stonehenge and to chart the subsequent history of the bluestones and their use at the monument. Evidence is presented for a provisional working date of around 2300 BC for the construction of the Double Bluestone Circle, while it is argued that the history of the site is far more complex than has been allowed for in existing interpretations, with a multiplicity of overlapping and intercutting (though not continuous) events, including substantial late Roman, medieval and early modern activity. The excavated material, and the evidence from the surviving stones, supports the suggestion that bluestones were brought to the site because of their perceived special qualities, perhaps for their supposed healing properties, and that some knowledge of those qualities remained current in later times with the result that in excess of two-thirds of the original bluestone volume has now disappeared

Tilted String Cosmologies

Global symmetries of the string effective action are employed to generate tilted, homogeneous Bianchi type VI_h string cosmologies from a previously known stiff perfect fluid solution to Einstein gravity. The dilaton field is not constant on the surfaces of homogeneity. The future asymptotic state of the models is interpreted as a plane wave and is itself an exact solution to the string equations of motion to all orders in the inverse string tension. An inhomogeneous generalization of the Bianchi type III model is also found.Comment: 9 pages, Standard Latex Source. To appear in Physics Letters B Minor change: Authors now alphabetically liste

Patched receptors sense, interpret and establish an epidermal Hedgehog signalling gradient

By using the sensitivity of single-molecule fluorescent in situ hybridization, we have precisely quantified the levels and defined the temporal and spatial distribution of Hedgehog signaling activity during embryonic skin development and discovered that there is a Hedgehog signaling gradient along the proximal-distal axis of developing hair follicles. To explore the contribution of Hedgehog receptors Ptch1 and Ptch2 in establishing the epidermal signaling gradient, we quantitated the level of pathway activity generated in Ptch1- and Ptch1; Ptch2-deficient skin and defined the contribution of each receptor to regulation of the levels of Hedgehog signaling identified in wild-type skin. Moreover, we show that both the cellular phenotype and level of pathway activity featured in Ptch1; Ptch2-deficient cells faithfully recapitulates the Peak level of endogenous Hedgehog signaling detected at the base of developing follicles, where the concentration of endogenous Shh is predicted to be highest. Taken together, these data show that both Ptch1 and Ptch2 play a crucial role in sensing the concentration of Hedgehog ligand and regulating the appropriate dose-dependent response

Atherosclerotic lesions in the thoracic aorta: A South African anatomical and histological mortuary study

Background. Worldwide, the prevalence of cardiovascular diseases such as atherosclerosis is on the increase. Younger people may be especially vulnerable owing to their exposure to risk factors such as drug abuse and HIV. Methods. The thoracic aortas of 149 South Africans under the age of 50 years were collected at the Salt River Mortuary, Cape Town, and examined macroscopically and microscopically for evidence of anomalies. The sample comprised predominantly males, and included black, coloured and white individuals. Results. A significantly higher level of macroscopic pathology was found in coloured males, although overall prevalence of pathology in this sample was lower than expected. A positive association was also found between body mass index and vascular pathology in the black and coloured population groups. Microscopic anomalies were common and present at high levels, irrespective of age and racial grouping. Conclusions. The widespread prevalence of microscopic anomalies in all groups suggests that these are normal variations that result from haemodynamic forces. The higher prevalence of atherosclerotic lesions in coloured males, however, probably results from specific genetic conditions such as hypercholesterolaemia or lifestyle factors such as diet or tik abuse. The findings suggest that coloured individuals may be at increased risk of developing cardiovascular disease

Atherosclerotic lesions in the thoracic aorta: A South African anatomical and histological mortuary study

Background. Worldwide, the prevalence of cardiovascular diseases such as atherosclerosis is on the increase. Younger people may be especially vulnerable owing to their exposure to risk factors such as drug abuse and HIV. Methods. The thoracic aortas of 149 South Africans under the age of 50 years were collected at the Salt River Mortuary, Cape Town, and examined macroscopically and microscopically for evidence of anomalies. The sample comprised predominantly males, and included black, coloured and white individuals. Results. A significantly higher level of macroscopic pathology was found in coloured males, although overall prevalence of pathology in this sample was lower than expected. A positive association was also found between body mass index and vascular pathology in the black and coloured population groups. Microscopic anomalies were common and present at high levels, irrespective of age and racial grouping. Conclusions. The widespread prevalence of microscopic anomalies in all groups suggests that these are normal variations that result from haemodynamic forces. The higher prevalence of atherosclerotic lesions in coloured males, however, probably results from specific genetic conditions such as hypercholesterolaemia or lifestyle factors such as diet or tik abuse. The findings suggest that coloured individuals may be at increased risk of developing cardiovascular disease