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Integrated Control Of Cereal Aphids/Barley Yellow Dwarf Virus, Elizabeth Jane Matcham Jan 1986

Integrated Control Of Cereal Aphids/Barley Yellow Dwarf Virus, Elizabeth Jane Matcham

Other Faculty of Science and Engineering Theses

The cereal aphids Rhopalosiphum padi (L.) and Sitobion a venae (F.) cause spread of Barley Yellow Dwarf Virus in autumn sown crops over the winter. Control is achieved by correctly timed insecticide applications, commonly synthetic pyrethroids. Polyphagous predators contribute to the natural control of these aphids. A field investigation into the effects of deltamethrin on polyphagous predators,using barriered plots, showed that natural control may be reduced due to the reduction in numbers of predators over the winter. Also, spring populations, which limit the growth of summer populations of aphids, may be reduced as larvae are most affected. The field dispersal …

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Dispersal In Carabids, Simon C. Newell Jan 1986

Dispersal In Carabids, Simon C. Newell

Other Faculty of Science and Engineering Theses

The study consisted primarily of a number of surveys in brassica fields, using pitfall and gutter traps. At all sites a number of different species of carabids were marked and released. From the pitfall trapping it was found that different carabid species inhabitated different parts of the field, particularly in relation to the field boundaries. Two common species, Nebria brevicollis and Bembidion lampros, over-wintered in the hedgebanks, moving out into the fields in the spring. Two other common species, Pterostichus melanarius and Harpalus rufipes, were primarily associated with the field, but activity in the field boundaries continued later into the …

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Voluntarism And The Criminal Justice System : A Comparative Analysis, Martin Laurence Gill Jan 1986

Voluntarism And The Criminal Justice System : A Comparative Analysis, Martin Laurence Gill

Other Faculty of Arts, Humanities and Business Theses

This thesis comparatively evaluates three groups of volunteers working within the criminal justice system in the South West of England. The groups chosen - probation Voluntary Associates, police Specials and Victims Support Scheme Volunteers - incorporate parties working with the offender, the public and the victim, ie those most closely identified with the judicial process. To date, research in both Britain and abroad has chosen to focus on a single agency which has limited our understanding of voluntarismo Nevertheless, most have identified a number of issues pertaining to the use of volunteers. Through a consideration of the type of work …

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Stability And Continuity In Cognitive Performance From Early To Late Infancy, Rachel Cooper Jan 1986

Stability And Continuity In Cognitive Performance From Early To Late Infancy, Rachel Cooper

Other Faculty of Arts, Humanities and Business Theses

This research is concerned with the stability and continuity of cognitive measures throughout the infancy period. A review of the literature showed that standardised infant intelligence tests fail to predict subsequent intellectual performance, and one reason for this may be the dominance of motor based items in the tests, and the relative dearth of measures reflecting cognitive ability. Furthermore, it has been suggested that measures from recently developed procedures, which are considered to reflect learning, memory and discriminative ability in infancy may constitute more useful predictive measures of later intellectual functioning. However, the reliabilities and inter-correlations between these measures have …

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Electrical Contact Bounce And The Control Dynamics Of Snap-Action Switches, John William Mcbride Jan 1986

Electrical Contact Bounce And The Control Dynamics Of Snap-Action Switches, John William Mcbride

School of Engineering, Computing and Mathematics Theses

Experimental and theoretical studies are made of a typical snap-action rocker switch, to establish the wear mechanisms in the pivoting contact. The rocker switch, used extensively in consumer goods, operates in the medium duty current range, (1 - 30 Amps). Highspeed photographic studies have shown that the main cause of wear is arcing, occurring during separation and bounce at the pivot contacts. To reduce the bounce a computer-based mathematical model of the system dynamics is developed and optimised; this results in recommended design changes. These changes are tested under full current endurance conditions, and show significant improvements in wear. The …

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The Galactic Magnetic Field, Belinda Jane Brett Jan 1986

The Galactic Magnetic Field, Belinda Jane Brett

School of Engineering, Computing and Mathematics Theses

The magnetic field of the Galaxy is investigated by spherical harmonic analysis of Faraday rotation measures of extragalactic sources and interstellar polarization measurements. Two methods of analysis are used. Initially, these are compared on synthetic data sets, and some problems illustrated. Faraday rotation measures of extragalactic radio sources are taken primarily from a recent catalogue (Simard-Normandin, Kronberg, and Button, 1981). These show certain trends with position in the sky, somewhat disrupted by random effects. A recently developed inverse theory method of spherical harmonic analysis gave an interesting quantitative indication of these trends, although some problems of analysis remain.

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A Multiple-Film Magnetoresistive Replay Head, For Audio Applications., Mark Lee Watson Jan 1986

A Multiple-Film Magnetoresistive Replay Head, For Audio Applications., Mark Lee Watson

School of Engineering, Computing and Mathematics Theses

Sensors have been fabricated, which are able to read the information stored on magnetic tape using the anisotropic magnetoresistance effect. These have major advantages over conventional replay heads in that they are multi-track devices, with very small trackwidths. To overcome the signal limitation imposed by the reduced trackwidth the sensor consists of two long magnetoresistive elements which are folded together. By differentially sensing the magnetoresistive signal in each of the elements second harmonic distortion can be removed. To improve the linearity of the magnetoresistive response, the sensors are arranged in such a way that the sensor signal current in each …

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The Determination Of Crack Propagation Rates Of Reflection Cracking Through Asphalt Surfacings, Timothy Nicholas Brooker Jan 1986

The Determination Of Crack Propagation Rates Of Reflection Cracking Through Asphalt Surfacings, Timothy Nicholas Brooker

School of Engineering, Computing and Mathematics Theses

A large proportion of the U.K. highway network constructed in the 1960's and 1970's contains lean concrete roadbase with bituminous surfacing. Pavements containing relatively high strength lean concrete have rarely required structural maintenance (thick overlay or reconstruction) but have required maintenance because of reflection cracking where the surfacing cracks above cracks in the lean concrete. The time of appearance of this cracking is very variable (2-20 years). Field observations indicate that roadbase transverse crack spacings are often greater than 5m. Reflection cracking at these long spacings can be caused by thermal stresses. This project identifies conditions under which thermal reflection …

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Anisotropy Of Heat Conduction In Fibre-Reinforced Composites, Sm Grove Oct 1985

Anisotropy Of Heat Conduction In Fibre-Reinforced Composites, Sm Grove

School of Engineering, Computing and Mathematics Theses

Fibre-reinforced composites usually exhibit anisotropy of thermal as well as mechanical properties. For example, in a unidirectional carbon fibre-reinforced plastic of 60% volume fraction, the longitudinal thermal conductivity may be greater than that in the transverse direction by a factor of 50, and greater than that of the unreinforced polymer by more than two orders of magnitude. In order to evaluate the engineering applications of thermal anisotropy, this thesis concentrates on the development and validation of a generalised finite element model of heat conduction in an anisotropic medium. This uses a variational formulation of the anisotropic time-dependent heat conduction equation, …

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The Effect Of Dietary Biotin Level On The Productivity Of The Female Pig, Philip Howard Simmins Jan 1985

The Effect Of Dietary Biotin Level On The Productivity Of The Female Pig, Philip Howard Simmins

School of Biological and Marine Sciences Theses

Five experiments were conducted with female pigs to investigate the effects of dietary biotin level on: reproductive performance and hoof integrity over four parities (experiment 1); ovulation rate of the gilt(experiment 2); durability of hoof horn and the phospholipid and neutral lipid profile of perinephric and hoof horn fat (experiments 3 and 4) and milk fat (experiment 5). Experiment 1 showed that changes in reproductive performance and hoof integrity in adult sows occurred when pigs were fed levels of dietary biotin previously considered to have been sufficient to meet the sow's requirements (diet calculated to provide32µg available biotin/kg). Notably, sows …

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Properties Of The Cell Surface Of Aeromonas Salmonicida, Nigel D. Parker Jan 1985

Properties Of The Cell Surface Of Aeromonas Salmonicida, Nigel D. Parker

School of Biological and Marine Sciences Theses

The properties of the cell surface of Aeromonas salmonicida were studied, with particular emphasis on the additional surface layer (A-layer), found on virulent strains. This was identified by electron microscopy, as having a tetragonal subunit morphology; and by electrophoresis of membrane components as a 51 kdal protein on A+ strains. A+ and A- strains, (the latter isolated by growth at elevated temperature), were compared biochemically and their interactions with various cell types investigated. Strains of A. salmonicida possessing the A-layer were shown to be more hydrophobic than those devoid of this protein. The influence of culture age, medium composition and …

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Ontogenetic Studies Of Immunity And Tolerance In Xenopus Laevis (Daudin), Ghassan Mahmoud Al-Johari Jan 1985

Ontogenetic Studies Of Immunity And Tolerance In Xenopus Laevis (Daudin), Ghassan Mahmoud Al-Johari

School of Biological and Marine Sciences Theses

Xenopus laevis injected with sheep erythrocytes (SRBC) at Stage 48 of Nieuwkoop and Faber (1967) showed no evidence of tolerance induction as a result of early exposure to antigen. These experiments showed that priming during the larval stages of development (at Stages 48 and 54 or at Stage 56) led to a positive anamnestic response when the animals were challenged after metamorphosis as toadlets. It was not, however, possible to demonstrate enhanced secondary responses within the larval period itself. The effect of the alkylating agent, cyclophosphamide on the generation of immunological memory varies at different stages of development. In the …

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Offshore Fouling Communities And Settlement And Early Growth In Tubularia Larynx (Ellis And Solander) And Pomatoceros Triqueter (L.), Roy Martin Moate Jan 1985

Offshore Fouling Communities And Settlement And Early Growth In Tubularia Larynx (Ellis And Solander) And Pomatoceros Triqueter (L.), Roy Martin Moate

School of Biological and Marine Sciences Theses

The horizontal and vertical distribution of the macro-fouling organisms, both flora and fauna, associated with offshore structures was studied. Offshore buoys located around the coasts of Britain (38) and Norway (10), were used as sites for the collection of material. Sites were visited annually, when possible, over the period 1978-1983. Numerical clustering techniques and indicator species analysis were used to reveal broad geographical categories in the fouling community data. Eight major Site Groups were identified amongst U.K. sites, and three from Norway; whilst within each site group characteristic species were also identified. The frequency and abundance of Tubularia larynx and …

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Inductively Coupled Plasma-Optical Emission Spectrometry For Forensic Analysis, Robert Christopher Carpenter Jan 1985

Inductively Coupled Plasma-Optical Emission Spectrometry For Forensic Analysis, Robert Christopher Carpenter

School of Geography, Earth and Environmental Sciences Theses

The fundamental characteristics and applications of inductively coupled plasma - optical emission spectrometry (ICP-OES) for forensic science purposes have been evaluated. Optimisation of ICP-OES for single elements using simplex techniques identified an ICP torch fitted with a wide bore injector tube as most suitable for multielement analysis because of a compact analytical region in the plasma. A suitable objective function has been proposed for multielement simplex optimisation of ICP-OES and its effectiveness has been demonstrated. The effects of easily ionisable element (EIE) interferences have been studied and an interference minimisation simplex optimisation shown to be appropriate for the location of …

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Directly-Coupled Chromatography - Analytical Atomic Spectroscopy For Trace Metal Speciation, Steve Hill Jan 1985

Directly-Coupled Chromatography - Analytical Atomic Spectroscopy For Trace Metal Speciation, Steve Hill

School of Geography, Earth and Environmental Sciences Theses

The form of trace metals, so called "speciation", is of vital importance in many fields, e.g., toxicology and environmental monitoring. A promising analytical approach to speciation studies is the coupling of chromatography, for species separation, to the selectivity and sensitivity of atomic spectroscopy for detection. The suitability of such couplings are discussed and the applications of both gas and liquid chromatography reviewed. The success of coupled gas chromatography (GC) - flame atomic absorption spectroscopy (FAAS) is demonstrated for the unequivocal identification of petrol residues in forensic applications. The advantages and disadvantages of this technique are discussed with reference to both …

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Geochemical Analysis By Inductively-Coupled Plasma Optical Emission Spectroscopy Using Slurry Atomization, Alison Ruth Gray Jan 1985

Geochemical Analysis By Inductively-Coupled Plasma Optical Emission Spectroscopy Using Slurry Atomization, Alison Ruth Gray

School of Geography, Earth and Environmental Sciences Theses

Elemental analysis by the nebulization of slurries of geological materials into an inductively coupled plasma has been investigated. High-solids nebulizers, spray chambers and torches have been designed and optimized for aqueous slurry introduction. The influence of particle size on sample introduction and atomization efficiency was shown to be paramount. Kaolin particles greater than 8 um were not atomized in the plasma. When the plasma operating parameters were optimized by simplex only the injector gas flow-rate and viewing height were critical. Clay suspensions of known concentration, varying particle size distributions, and concentration s o f 0.2 to 20% w/v were prepared …

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The Provision Of Small Industrial Premises: A Geographical Perspective, Martin Perry Jan 1985

The Provision Of Small Industrial Premises: A Geographical Perspective, Martin Perry

School of Geography, Earth and Environmental Sciences Theses

This thesis develops the argument that Industrial Geography research could be strengthened and enriched by the use of ideas current in the study of the Social Geography of housing. The analysis of accommodation supply and management, which has provided valuable new insights into residential structure, has so far no counterpart in Industrial Geography, and yet the constraints imposed by property availability obviously fashion the prospectus from which locational choices must be made.

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A Foraminiferal Biostratigraphy Of The Upper Cretaceous Of The Southern North Sea Basin (Uk Sector)., Kim C. Ball Jan 1985

A Foraminiferal Biostratigraphy Of The Upper Cretaceous Of The Southern North Sea Basin (Uk Sector)., Kim C. Ball

School of Geography, Earth and Environmental Sciences Theses

The Cenomanian to Maastrictian foraminifera have been studied from borehole material (ditchcuttings) of three wells - 44/2-1,49/19-1 and 49/20-2 - drilled by Shell (UK) Exploration & Production Ltd in the Southern North Sea Basin. The microfaunas have been utilized in the formulation of a zonal scheme comprising twelve foraminiferal biozones based on 'tops' (highest occurrences) of selected taxa; the taxonomy of the stratigraphically diagnostic forms is briefly discussed. The major lithostratigraphic units of the Dutch and British sectors of the Upper Cretaceous of the Southern North Sea Basin are recognised from Gamma Ray and Formation Density wireline log signitures (where …

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The Determination Of Trace Metals By High Performance Liquid Chromatography With Photometric Detection, Philip John Hobbs Jan 1985

The Determination Of Trace Metals By High Performance Liquid Chromatography With Photometric Detection, Philip John Hobbs

School of Geography, Earth and Environmental Sciences Theses

The importance of trace metals and their species is reviewed and it is recognised that improved methods of determination are required. High performance liquid chromatography has grown in importance as a technique, especially since the synthesis of better column packings. The adaptability of reverse phase and ion chromatography with new post-column reagents for photometric detection for the determination of transition metal cations, is discussed. Separation of divalent transition metal by high performance chromatography was improved by eluents used in column ion chromatography, new eluents were also assessed. Lactate eluents were particularly effective and tartrate, oxalate and thiomalic buffers also showed …

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Organisational And Institutional Environmental Effects Upon Merchant Marine Officers' Occupational Commitment, Nadav Sonnenberg Jan 1985

Organisational And Institutional Environmental Effects Upon Merchant Marine Officers' Occupational Commitment, Nadav Sonnenberg

Other Faculty of Science and Engineering Theses

The thesis is concerned to examine the area of occupational commitment of merchant marine officers. From a general description of the occupation and its relationship to the wider environment the study focusses specifically upon the Israeli case. A review of recent literature on commitment and labour turnover demonstrates the inter-disciplinary approaches taken by previous researchers and, importantly, suggests that commitment and turnover are two quite complementary constructs. The emphasis in this study is upon the antecedents and causes of occupational commitment - an emphasis that has been relatively neglected in earlier work. The theoretical model established takes individual intentions as …

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Computer Simulation Of Marine Traffic Systems, B.A. Colley Jan 1985

Computer Simulation Of Marine Traffic Systems, B.A. Colley

Other Faculty of Science and Engineering Theses

A computer model was constructed that allowed two vessels involved in a possible collision situation to take collision avoidance action following the "International Regulations for Preventing Collisions at Sea". The mariners’ actions were modelled by the concepts of the domain and the RDRR (Range to Domain/Range-rate). The domain was used to determine if a vessel was threatening and the RDRR to determine the time at which a vessel should give-way to a threatening target. Each vessel in the simulation had four domains corresponding to the type of encounter in which the vessel was involved. Values for the time at which …

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Ecological Aspects Of Hepatic Microsporidiosis In Coastal Waters With Particular Reference To The Host Taurulus Bubalis, Juliet Anne Stubbs Jan 1985

Ecological Aspects Of Hepatic Microsporidiosis In Coastal Waters With Particular Reference To The Host Taurulus Bubalis, Juliet Anne Stubbs

School of Biological and Marine Sciences Theses

Hepatic microsporidia were investigated from 5 species of fish, namely Taurulus bubalis (Euphr.), Crenilabrus melops, (L.), Gaidropsarus mediterraneus (L.), Ciliata mustela (L.). and Scophthalmus maximus (L.) and intramuscular microsporidia from 2 species, namely Taurulus bubalis and Cottus gobio L. Detailed ultrastructural studies carried out on hepatic microsporidia from T. bubalis showed it to be a new species belonging to the genus Microgemma (Ralphs) and it is named here as Microgemma dunkerli sp. n. Although hepatic microsporidia from the other species of fish are included in Microgemma, insufficient data was available to determine whether these were synonomous with M. dunkerli or …

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The Social Impact Of Seasonal Employment In Devon And Cornwalll, Ingrid Faerden Jan 1985

The Social Impact Of Seasonal Employment In Devon And Cornwalll, Ingrid Faerden

School of Law, Humanities and Social Sciences Theses

This thesis reports on a study of seasonal employment in the tourist industry of Devon and Cornwall. The study is based upon official data, employer interviews and interviews with seasonal workers in eight organisations during the Su7n r of 1983. In the Summer months, the tourist industry is of considerable importance in the area both from a general economic point of view as well as a provider of employment. The real benefit of seasonal employment is, however, questioned sirce such large groups of people are left without work during the Winter months. Furthermore, working conditions for seasonal workers are poor …

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The Output Frequency Spectrum Of A Thyristor Phase-Controlled Cycloconverter Using Digital Control Techniques, Chiu Hon Leung Jan 1985

The Output Frequency Spectrum Of A Thyristor Phase-Controlled Cycloconverter Using Digital Control Techniques, Chiu Hon Leung

School of Engineering, Computing and Mathematics Theses

The principle of operation dictates that the output of a cycloconverter contains some harmonics. For drive applications, the harmonics at best increase losses in the motor and may well cause instability. Various methods of analysing the output waveform have been considered. A Fortran 77 program employing a modified Fourier series, making use of the fact that the input waveforms are sinusoidal, was used to compute the individual harmonic amplitudes. A six pulse three phase to single phase cycloconverter was built and a Z-80 microprocessor was used for the control of firing angles. Phase locked loops were used for timing, and …

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Microprocessor Based Non-Linear Adaptive Controller, K. L. Yung Jan 1985

Microprocessor Based Non-Linear Adaptive Controller, K. L. Yung

School of Engineering, Computing and Mathematics Theses

The advent of microprocessors has created the possibility of developing low cost adaptive controllers for small process plants which in the past badly needed but could not afford such controllers. To examine the practicality of developing advanced low cost microprocessor based controller, this thesis describes the development of a non-linear adaptive controller for a nylon crimping plant which is a typical example of small process plants. In order to test the algorithm on site, an algorithm development/implement device basing on a novel multi-tasking concept was developed. This novel microprocessor based device can perform program development, on-line algorithm test and data …

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The Development And Assessment Of An Analytical Structural Maintenance Design System For Roads, V. Bala Kumar Jan 1985

The Development And Assessment Of An Analytical Structural Maintenance Design System For Roads, V. Bala Kumar

School of Engineering, Computing and Mathematics Theses

Previous work at Plymouth has shown the deflected shape as measured by the Deflectograph can be used to estimate the thickness of surfacing. This thesis extends the earlier work to develop relations between deflected shape and the stiffness and thickness of pavement layers. A literature study has been carried out to identify the factors causing the deterioration of flexible pavements. The literature study also assesses the various pavement evaluation equipment that is available and describes various methods of analysis and the interpretation of the pavement surface deflection shape that have been proposed. The properties of the materials of the various …

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Immunological Memory In Young Fish And Amphibians: Studies On Cyprinus Carpio, Chelon Labrosus And Xenopus Laevis, Mohammad Sharif Mughal Jan 1984

Immunological Memory In Young Fish And Amphibians: Studies On Cyprinus Carpio, Chelon Labrosus And Xenopus Laevis, Mohammad Sharif Mughal

School of Biological and Marine Sciences Theses

This study asks whether antigens encountered early in life by animals with free-living larvae can prime the immune system to yield memory responses on subsequent exposure and, if so, whether positive immunity or immunological tolerance is induced. In 4-week old carp, Cyprinus carpio, the thymus dependent antigen human gamma globulin (HGG) was tolerogenic both in soluble form and attached to latex particles, Formalin-killed Aeromonas salmonicida bacteria, in contrast, elicited primary antibody production and induced enhanced secondary responses. By the age of 9-10 weeks HGG was no longer tolerogenic even when injected into the thymus or administered orally. Despite their antibody …

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Geochemical Cycles Of The Atmophile Elements Arsenic And Antimony, Laurence Stuart Austin Jan 1984

Geochemical Cycles Of The Atmophile Elements Arsenic And Antimony, Laurence Stuart Austin

School of Biological and Marine Sciences Theses

Atmospheric aerosol samples from coastal and open ocean environments in the North Atlantic were analysed for the atmophile elements arsenic and antimony, and for the marine tracers sodium and magnesium. The aerosol concentrations of sodium and magnesium were similar in both environments, about 2000 ng Na (SCM)ˉ¹ and 320 ng Mg (SCM)ˉ¹. The atmophiles were more concentrated in the coastal aerosol, 0.67 ng As(SCM)ˉ¹ and 0.32 ng Sb (SCM)ˉ¹, than in the open ocean aerosol, 0.07 ng As (SCM)ˉ¹ and 0.086 ng Sb (SCM)ˉ¹, and as continental particles were only observed in the coastal aerosol, this indicates that arsenic and …

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The Sedimentology And Palaeogeography Of Some Devonian Sedimentary Rocks In Southwest Ireland, Kenneth Russell Jan 1984

The Sedimentology And Palaeogeography Of Some Devonian Sedimentary Rocks In Southwest Ireland, Kenneth Russell

School of Geography, Earth and Environmental Sciences Theses

The area investigated for this thesis is the western end of the Iveragh Peninsula, Co. Kerry, southwest Ireland. The rocks in the area are predominantly of Old Red Sandstone facies, totalling over 6600m in thickness, and were deposited near the northern fault-bounded margin of the extensive half-graben feature known as the Munster Basin. Towards the end of the basin's history, continental conditions were replaced by marginal marine as the sea transgressed into the area from the south. The objectives of the study are to provide a description of the poorly known sedimentary facies from this part of the basin, to …

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The Automatic Control Of Large Ships In Confined Waters, Roland Stephen Burns Jan 1984

The Automatic Control Of Large Ships In Confined Waters, Roland Stephen Burns

Other Faculty of Science and Engineering Theses

The design and evaluation of a control system, which can be utilised for the automatic guidance of large ships in confined or restricted waters, is investigated. The vessel is assumed to be a multivariable system and it is demonstrated that a non-linear, time-varying mathematical model most accurately describes the motion of the hull, particularly in tight manoeuvres. A discrete optimal controller has been designed to control simultaneously track, heading and forward velocity. The system is most effective whilst operating under a dual-mode policy. It is shown that feedback matrix adaption is necessary to deal with changes in forward velocity and …

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