Friction stir welding of thin DH36 steel plate

A series of 4, 6 and 8 mm DH36 steel welds were produced using optimum conditions for friction stir welding (FSW). Comparator welds in the same thickness from the same plates were produced using a single sided single pass process submerged arc welds (SAW). This work was carried out to evaluate the mechanical properties of FSW material with a view to its possible application in a shipbuilding production process route. Overall, the performance of the FSW material was superior to the SAW comparators. Areas such as distortion and fatigue were particularly positive in the FSW material. An 8 mm thick plate was also produced using two FSW passes, one from either side, and it was found to have superior toughness and fatigue performance when compared to the single sided 8 mm FSW material. Some of these benefits are thought to have originated from the internal overlap zone between the two passes

How overconfident are current projections of anthropogenic carbon dioxide emissions?

Analyzing the risks of anthropogenic climate change requires sound probabilistic projections of CO2 emissions. Previous projections have broken important new ground, but many rely on out-of-range projections, are limited to the 21st century, or provide only implicit probabilistic information. Here we take a step towards resolving these problems by assimilating globally aggregated observations of population size, economic output, and CO2 emissions over the last three centuries into a simple economic model. We use this model to derive probabilistic projections of business-as-usual CO2 emissions to the year 2150. We demonstrate how the common practice to limit the calibration timescale to decades can result in biased and overconfident projections. The range of several CO2 emission scenarios (e.g., from the Special Report on Emission Scenarios) misses potentially important tails of our projected probability density function. Studies that have interpreted the range of CO2 emission scenarios as an approximation for the full forcing uncertainty may well be biased towards overconfident climate change projections.economics of climate change, scenarios, data assimilation

How Overconfident are Current Projections of Anthropogenic Carbon Dioxide Emissions?

Analyzing the risks of anthropogenic climate change requires sound probabilistic projections of CO2 emissions. Previous projections have broken important new ground, but many rely on out-of-range projections, are limited to the 21st century, or provide only implicit probabilistic information. Here we take a step towards resolving these problems by assimilating globally aggregated observations of population size, economic output, and CO2 emissions over the last three centuries into a simple economic model. We use this model to derive probabilistic projections of business-as-usual CO2 emissions to the year 2150. We demonstrate how the common practice to limit the calibration timescale to decades can result in biased and overconfident projections. The range of several CO2 emission scenarios (e.g., from the Special Report on Emission Scenarios) misses potentially important tails of our projected probability density function. Studies that have interpreted the range of CO2 emission scenarios as an approximation for the full forcing uncertainty may well be biased towards overconfident climate change projections.Carbon Dioxide, Emissions, Scenarios, Data Assimilation, Markov Chain Monte Carlo

Discovery of heterometallic layered oxides using solid-state reactions of nano-Precursors

The synthesis of new solid-state materials is often a laborious task due to the low speed of diffusion in bulk solids, meaning each reaction requires hightemperatures and multiple steps. Shortening diffusion distances has been shown to increase reaction rates and lower reaction temperatures. This thesis addresses the need to increase the rate of solid-state materials discovery, by heat-treatment of nanosized precursors. The nano-precursors were synthesised using continuous hydrothermal flow synthesis, CHFS. In CHFS a flow of metal nitrate salts are brought into contact with a flow of supercritical water to precipitate metal oxides and/or hydroxides. The reaction between La(OH)3 and Ni(OH)2 co-precipitated using CHFS was investigated using in-situ X-ray diffraction. This resulted in the formation of La2NiO4 in 78 minutes, an order of magnitude faster than when using more traditional routes, highlighting the effectiveness of this approach. A high-throughput CHFS reactor was then used to synthesise La4Ni2.7M0.3O10-δ (where M = V, Cr, Mn, Fe, Co, Cu and Al). By calcining the nanoprecursors for these compositions in parallel it was possible to reduce the synthesis time to make twenty-four solid-state compounds to 12 hours. Structure and properties were screened and, La4Ni2.7V0.3O10-δ, La4Ni2.7Cr0.3O10-δ, La4Ni2.7Mn0.3O10-δ and La4Ni2.7Al0.3O10-δ were characterised. Subsequently this process was carried out using automation to increase the number of compositions synthesised. Firstly, for the La4Ni3-xFexO10-δ system (x = 0.0 – 3.0 and Δx = 0.1), 62 samples were synthesised, resulting in identifying a greatly increased phase boundary, up to a maximum Fe content of La4Ni2.06Fe0.94O10. Secondly for the La4Ni3-xMxO10-δ and La3Ni2-xMxO7-δ systems (x = 0.0 – 2.0. Δx = 0.2 and M = Mn, Al, Pd, Ga) in which 240 samples were synthesised. La4Ni3-xGaxO10-δ was isolated up to a maximum Ga content of x = 0.6, and La2Ni1-xPdxO4 could be synthesised with a maximum Pd content of x = 0.4

Conceptual Ecological Modelling of Shallow Sublittoral Sand Habitats to Inform Indicator Selection

The purpose of this study is to produce a series of conceptual ecological models (CEMs) which represent shallow sublittoral sand habitats in the UK. CEMs are diagrammatic representations of the influences and processes which occur within an ecosystem. They can be used to identify critical aspects of an ecosystem which may be taken forward for further study, or serve as the basis for the selection of indicators for environmental monitoring purposes. The models produced by this project are control diagrams, representing the unimpacted state of the environment free from anthropogenic pressures. The project scope included the Marine Strategy Framework Directive (MSFD) predominant habitat type ‘shallow sublittoral sand’. This definition includes those habitats which fall into the EUNIS Level 4 classifications A5.23 Infralittoral Fine Sand, A5.24 Infralittoral Muddy Sand, A5.25 Circalittoral Fine Sand and A5.26 Circalittoral Muddy Sand, along with their constituent Level 5 biotopes which are relevant to UK waters. A species list of characterising fauna to be included within the scope of the models was identified using an iterative process to refine the full list of species found within the relevant Level 5 biotopes. A literature review was conducted to gather evidence regarding species traits and information to inform the models. All information gathered during the literature review was entered into a data logging pro forma spreadsheet which accompanies this report. Wherever possible, attempts were made to collect information from UK-specific peer-reviewed studies, although other sources were used where necessary. All data gathered was subject to a detailed confidence assessment. Expert judgement by the project team was utilised to provide information for aspects of the models for which references could not be sourced within the project timeframe. A model hierarchy was developed based on groups of fauna with similar species traits which aligned with previous sensitivity studies of ecological groups. A general model was produced to indicate the high level drivers, inputs, biological assemblages, ecosystem processes and outputs which occur in shallow sublittoral sand habitats. In addition to this, four detailed sub-models were produced. Each focussed on a particular functional group of fauna within the habitat: “suspension and deposit feeding infauna”, “small mobile fauna and tube dwelling species”, “mobile epifauna, scavengers and predators”, and “attached epifauna and macroalgae”. Each sub-model is accompanied by an associated confidence model which presents confidence in the links between each model component. The models are split into seven levels and take spatial and temporal scale into account through their design, as well as magnitude and direction of influence. The seven levels include regional to global drivers, water column processes, local inputs/processes at the seabed, habitat and biological assemblage, output processes, local ecosystem functions, and regional to global ecosystem functions. The models indicate that whilst the high level drivers which affect each functional group are largely similar, the output processes performed by the biota and the resulting ecosystem functions vary both in number and importance between groups. Confidence within the models as a whole is generally high, reflecting the level of information gathered during the literature review. Important drivers which influence the ecosystem include factors such as wave exposure, depth, water currents, climate and propagule supply. These factors, in combination with seabed and water column processes such as primary production, seabed mobility, suspended sediments, water chemistry and temperature and recruitment define and influence the biological assemblages. In addition, the habitat sediment type plays an important factor in shaping the biology of the habitat. Conceptual Ecological Modelling of Shallow Sublittoral Sand Habitats Output processes are variable between functional faunal groups depending on the fauna present. Important processes include secondary production, biodeposition, bioturbation, bioengineering and the supply of propagules. These influence ecosystem functions at the local scale such as nutrient and biogeochemical cycling, supply of food resources, sediment stability, habitat provision and in some cases microbial activity. The export of biodiversity and organic matter, biodiversity enhancement and biotope stability are the resulting ecosystem functions which occur at the regional to global scale. Features within the models which are most useful for monitoring habitat status and change due to natural variation have been identified using the information gathered during the literature review, through interpretation of the models and through the application of expert judgement. Features within the models which may be useful for monitoring to identify anthropogenic causes of change within the ecosystem have also been identified. Physical and biological features of the ecosystem have mostly been identified as potential indicators to monitor natural variation, whilst physical features and output processes have predominantly been identified as most likely to indicate change due to anthropogenic pressures

Conceptual Ecological Modelling of Shallow Sublittoral Mixed Sediment Habitats to Inform Indicator Selection.

The purpose of this study is to produce a series of conceptual ecological models (CEMs) which represent shallow sublittoral mixed sediment habitats in the UK. CEMs are diagrammatic representations of the influences and processes which occur within an ecosystem. They can be used to identify critical aspects of an ecosystem which may be taken forward for further study, or serve as the basis for the selection of indicators for environmental monitoring purposes. The models produced by this project are control diagrams, representing the unimpacted state of the environment free from anthropogenic pressures. The project scope included the Marine Strategy Framework Directive (MSFD) predominant habitat type ‘shallow sublittoral mixed sediment’. This definition includes those habitats which fall into the EUNIS Level 4 classifications A5.43 Infralittoral Mixed Sediments and A5.44 Circalittoral Mixed Sediments, along with their constituent Level 5 biotopes which are relevant to UK waters. A species list of characterising fauna to be included within the scope of the models was identified using an iterative process to refine the full list of species found within the relevant Level 5 biotopes. A literature review was conducted to gather evidence regarding species traits and information to inform the models. All information gathered during the literature review was entered into a data logging pro forma spreadsheet which accompanies this report. Wherever possible, attempts were made to collect information from UK-specific peer-reviewed studies, although other sources were used where necessary. All data gathered was subject to a detailed confidence assessment. Expert judgement by the project team was utilised to provide information for aspects of the models for which references could not be sourced within the project timeframe. A model hierarchy was developed based on groups of fauna with similar species traits which aligned with previous sensitivity studies of ecological groups. A general model was produced to indicate the high level drivers, inputs, biological assemblages, ecosystem processes and outputs which occur in shallow sublittoral mixed sediment habitats. In addition to this, five detailed sub-models were produced. Each focussed on a particular functional group of fauna within the habitat: ‘temporary or permanently attached epifauna’, ‘mobile epifauna, scavengers and predators’, ‘suspension and deposit feeding fauna’, ‘temporary or permanently attached surface dwelling or shallowly buried larger bivalves’ and ‘small mobile epifauna and tube dwelling crustaceans’. Each sub-model is accompanied by an associated confidence model which presents confidence in the links between each model component. The models are split into seven levels and take spatial and temporal scale into account through their design, as well as magnitude and direction of influence. The seven levels include regional to global drivers, water column processes, local inputs/processes at the seabed, habitat and biological assemblage, output processes, local ecosystem functions, and regional to global ecosystem functions. The models indicate that whilst the high level drivers which affect each functional group are largely similar, the output processes performed by the biota and the resulting ecosystem functions vary both in number and importance between groups. Confidence within the models as a whole is generally high, reflecting the level of information gathered during the literature review. Important drivers which influence the ecosystem include factors such as wave exposure, depth, water currents, climate and propagule supply. These factors, in combination with seabed and water column processes such as primary production, seabed mobility, suspended sediments, water chemistry and temperature and recruitment define and Conceptual Ecological Modelling of Shallow Sublittoral Mixed Sediment Habitats influence the biological assemblages. In addition, the habitat sediment type plays an important factor in shaping the biology of the habitat. Output processes are variable between functional faunal groups depending on the fauna present. Important processes include secondary production, biodeposition, bioturbation, bioengineering and the supply of propagules. These influence ecosystem functions at the local scale such as nutrient and biogeochemical cycling, supply of food resources, sediment stability, habitat provision and in some cases microbial activity. The export of biodiversity and organic matter, biodiversity enhancement and biotope stability are the resulting ecosystem functions which occur at the regional to global scale. Features within the models which are most useful for monitoring habitat status and change due to natural variation have been identified using the information gathered during the literature review, through interpretation of the models and through the application of expert judgement. Features within the models which may be useful for monitoring to identify anthropogenic causes of change within the ecosystem have also been identified. Physical and biological features of the ecosystem have mostly been identified as potential indicators to monitor natural variation, whilst physical features and output processes have predominantly been identified as most likely to indicate change due to anthropogenic pressures

Superplastic behaviour of AZ91 magnesium alloy processed by high– pressure torsion

An investigation has been conducted on the tensile properties of a fine–grained AZ91 magnesium alloy processed at room temperature by high pressure torsion (HPT). Tensile testing was carried out at 423 K, 473 K and 573 K using strain rates from 1×10–1 s–1 to 1×10–4 s–1 for samples processed in HPT for N = 1, 3, 5 and 10 turns. After testing was completed, the microstructures were investigated by scanning electron microscopy and energy dispersive spectroscopy. The alloy processed at room temperature in HPT exhibited excellent superplastic behaviour with elongations higher than elongations reported previously for fine–grained AZ91 alloy produced by other severe plastic deformation processes, e.g. HPT, ECAP and EX–ECAP. A maximum elongation of 1308 % was achieved at a testing temperature of 573 K using a strain rate of 1×10–4 s–1, which is the highest value of elongation reported to date in this alloy. Excellent high–strain rate superplasticity (HSRSP) was achieved with maximum elongations of 590 % and 860 % at temperatures of 473 K and 573 K, respectively, using a strain rate of 1×10–2 s–1. The alloy exhibited low–temperature superplasticity (LTSP) with maximum elongations of 660 % and 760 % at a temperature of 423 K and using strain rates of 1×10–3 s–1 and 1×10–4 s–1, respectively. Grain–boundary sliding (GBS) was identified as the deformation mechanism during HSRSP, and the glide–dislocation creep accommodated by GBS dominated during LTSP. Grain–boundary sliding accommodated with diffusion creep was the deformation mechanism at high test temperature and slow strain rates. An enhanced thermal stability of the microstructure consisting of fine equiaxed grains during deformation at elevated temperature was attributed to the extremely fine grains produced in HPT at room temperature, a high volume fraction of nano ?–particles, and the formation of ?–phase filaments

A comparison of the helminth communities in Anas undulata, Anas erythrorhyncha, Anas capensis and Anas smithii at Barberspan, South Africa

Examination of the helminth communities in 25 yellow-billed ducks (Anas undulata), 21 red-billed ducks (Anas erythrorhyncha), ten Cape teal (Anas capensis) and seven Cape shovellers (Anas smithii) that had overwintered at Barberspan, revealed differences in community structure. Infracommunities in yellow-billed and red-billed ducks were characterized by low diversity and high eveness, and generally consisted of less than 100 helminths per duck. Similarity values (mean percent similarity and mean Jaccard's coefficients) were low. In contrast, infracommunities in Cape teal and Cape shovellers were more diverse, displayed low eveness values and consisted of far greater numbers of helminths. Mean similarity values for the infracommunities in Cape teal and Cape shovellers were much higher than those in yellow-billed or red-billed ducks. The component communities in all four duck hosts were species rich. Those in yellow-billed and red-billed ducks, however, consisted predominantly of satellite species and no core species were present, whereas those in Cape teal and Cape shoveller included several core species. Cape teal and Cape shovellers each had a group of recurrent species but there was not much of a tendency for species to co-occur in yellow-billed and red-billed ducks. Multivariate analysis revealed a greater similarity between the communities in Cape teal and Cape shovellers than between the latter and the communities in yellow- billed or red-billed ducks. Communities in Cape teal and Cape shovellers could be distinguished from each other by the presence or absence of particular cestode species. The communities in these two species could be distinguished from those in yellow-billed or red-billed ducks by a suite of cestode species that was absent in the latter two. Two recurrent groups, consisting of eight and two species, were identified in the compound community. Each group consisted of species found predominantly in Cape teal and Cape shovellers. Patterns seen in the helminth communities of the various hosts reflected differences in diet, but other factors, including feeding behaviour, spatial segregation and host specificity, may also have had an effect.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Natural Sciences and Engineering Council of Canada. Concordia University

A checklist of helminths from the respiratory system and gastrointestinal tracts of African Anatidae

A literature survey revealed that 72 helminth species, including 14 known only to the generic level, had been reported from the digestive or respiratory tracts of 28 species of Anatidae in Africa. Most of the digeneans and nematodes reported, were cosmopolitan species that occur in a range of hosts. However, two groups of cestodes, one consisting of cosmopolitan or Eurasian species and the other consisting of species restricted mainly to sub-Saharan Africa, were apparent. A host-parasite list and a detailed parasite-host list provide the synyonomies related to African records, the host and geographical distribution of each species, and the authority and country of origin for each record.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat X Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Natural Sciences and Engineering Research Council of Canada. Concordia University

Probing for the Charm Content of BB and Υ\Upsilon Mesons

A slow $J/\psi$ bump exists in the inclusive $B\to J/\psi + X$ spectrum, while the softness of $J/\psi$ spectrum in $\Upsilon(1S) \to J/\psi + X$ decay is in strong contrast with expectations from color octet mechanism. We propose {\it intrinsic} charm as the explanation:the former is due to $\bar B\to J/\psi D \pi$,with three charm quarks in the final state; the latter is just a small fraction of $\Upsilon(1S) \to (c\bar c)_{\rm slow} + 2$"jet" events, where the slow moving $c\bar c$ system evolves into $D^{(*)}$ pairs. Experimental search for these phenomena at B Factories and the Tevatron is strongly urged, as the implications go beyond QCD.Comment: 4 pages, REVTEX, 10 eps figures included. Major revision with more discussions on the rescattering background, and a reappraisal of the Upsilon(1S) decay in the presence of intrinsic charm, leading to a change in Titl