Últimos itens adicionados do Acervo: University of Limerick

A University of Limerick é uma universidade pública na cidade de Limerick, Irlanda. Foi fundada em 1972.

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Language trends: Reflexivity in commercial language policies and practices

Kelly-Holmes, Helen
Fonte: Walter de Gruyter Publicador: Walter de Gruyter
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Financier, philanthropist and economist George Soros is not the first to have used or derived the notion of reflexivity (for example, Anthony Giddens, Ulrich Beck and others have found it useful in their work).What is different about the approach of Soros is that he has used the concept of reflexivity to explain the workings of global markets, and for this reason his work seems to me to have particular potential for explaining language trends in the linguistic policies and practices of global marketers. Soros has challenged ruling economic orthodoxy by arguing that demand and supply are not given or objective, and far from determining how markets develop. Participants in economic processes inevitably and unavoidably shape and determine the outcome of those economic processes and also create the conditions for future development of those market processes. This particular insight, I would argue, could help us to understand and develop further the notion of normativity in‘global’linguistic practices and policies, particularly when linked to economic processes since “the self-validating capacity [of such processes] encourages trend-following speculation” (Soros 1994). We can equate the decisions of many global marketers to that of stock brokers...

A temporary problem in Ireland

Keane, Eddie
Fonte: Queen's University Belfast, School of Law Publicador: Queen's University Belfast, School of Law
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; ACCEPTED; peer-reviewed

Rearing an unexpected child: a compensatory matter?

Keane, Eddie
Fonte: Thomson Round Hall Publicador: Thomson Round Hall
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; When speaking of damages in Tort law Salmond & Heuston state “[i]t is often discussed whether the governing principle is that of restitutio in integrum, or whether the defendant is only obliged to give the plaintiff fair compensation”. It would seem that in most situations where damages are assessed the courts consider fair compensation to be a monetary sum, based on actuarial evidence, which would amount to restitutio in integrum. Thus, in practice, the distinction between the principles is often blurred. However, some specific situations call for a deeper examination of the concept of fair compensation. A recent example is Byrne v Ryan where the Irish High Court was faced with determining what would constitute fair compensation for the negligent performance of a sterilisation operation. The case raised some interesting issues such as the role of public policy in determining the extent of recoverability and how such public policy is formed. The questions of how harm is defined and what exactly could be termed a recoverable loss were also raised.; PUBLISHED; peer-reviewed

Novel Tn4371-ICE like element in Ralstonia pickettii and Genome mining for comparative elements

Ryan, Michael P; Pembroke, Tony J; Adley, Catherine C
Fonte: BioMed Central Publicador: BioMed Central
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Background: Integrative Conjugative Elements (ICEs) are important factors in the plasticity of microbial genomes. An element related to the ICE Tn4371 was discovered during a bioinformatic search of the Ralstonia pickettii 12J genome. This element was analysed and further searches carried out for additional elements. A PCR method was designed to detect and characterise new elements of this type based on this scaffold and a culture collection of fifty-eight Ralstonia pickettii and Ralstonia insidiosa strains were analysed for the presence of the element. Results: Comparative sequence analysis of bacterial genomes has revealed the presence of a number of uncharacterised Tn4371-like ICEs in the genomes of several beta and gamma Proteobacteria. These elements vary in size, GC content, putative function and have a mosaic-like structure of plasmid- and phage-like sequences which is typical of Tn4371-like ICEs. These elements were found after a through search of the GenBank database. The elements, which are found in Ralstonia, Delftia, Acidovorax, Bordetella, Comamonas, Acidovorax, Congregibacter, Shewanella, Pseudomonas Stenotrophomonas, Thioalkalivibrio sp. HL-EbGR7, Polaromonas, Burkholderia and Diaphorobacter sp. share a common scaffold. A PCR method was designed (based on the Tn4371-like element detected in the Ralstonia pickettii 12J genome) to detect and characterise new elements of this type. Conclusion: All elements found in this study possess a common scaffold of core genes but contain different accessory genes. A new uniform nomenclature is suggested for ICEs of the Tn4371 family. Two novel Tn4371-like ICE were discovered and characterised...

Cold compression residual stress reduction in aluminum alloy 7010

Tanner, D.A; Robinson, J.S; Cudd, Richard L
Fonte: Trans Tech Publications Publicador: Trans Tech Publications
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; 7010 is one of the high strength aluminium alloys used mainly as plate and forgings in the aerospace industry. Its high strength is achieved through a quenching operation where the material is rapidly cooled from the solution heat treatment temperature (475°C) to room temperature. As with all rapid quenching operations, residual stresses develop, leaving the material unsuitable for further machining operations and for service. Regular shaped forgings are generally cold compressed after quenching to relieve residual stresses. The effect of friction, increasing/decreasing the amount of cold compression and applying cold compression in ‘bites’ on residual stress magnitudes is unknown. This paper aims to study the effect that these variables have on final residual stress patterns through use of a finite element model.; Accepted; peer-reviewed

Residual stress prediction and determination in 7010 aluminum alloy forgings

Tanner, D.A; Robinson, J.S
Fonte: Springer Publicador: Springer
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Precipitation-hardened aluminum alloys gain their high strength through heat treatment involving a severe quenching operation, which can have the adverse effect of introducing residual stresses. The finite element code ABAQUS is used to simulate the quenching of aluminum alloy 7010 in an attempt to predict the residual stress distribution that develops in simple shapes, The rate of heat transfer from the material is determined using the finite element method to predict the heat transfer coefficient from surface cooling curves achieved experimentally. The flow stress of the material is assumed to be strain rate dependent and to behave in a perfectly plastic manner. The predicted residual stress magnitudes and directions are compared to values determined using the hole-drilling strain gage method and the X-ray diffraction technique.; Accepted; peer-reviewed

Quench sensitivity and tensile property inhomogeneity in 7010 forgings

Robinson, J.S; Cudd, Richard L; Tanner, D.A; Dolan, G.P
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; 7xxx (Al-Zn-Mg-Cu) alloys develop their strength, through the controlled decomposition (ageing) of a supersaturated solid solution to produce a precipitation hardened microstructure. The supersaturated solid solution is normally produced by water quenching from the solution heat treatment temperature. The kinetics of phase transformations occurring during cooling from the solution heat treatment temperature are limited at small undercoolings by the small chemical free energy, and as the undercooling increases, by reduced rates of substitutional solid state diffusion. This gives rise to the characteristic C-shape of time-temperature-property (TTP) curves. The TTP curve for 7010 has been evaluated by a interrupted quench method into a salt bath at temperatures ranging from 450 to 210degreesC. A TTP curve for 7050T76 sheet data has then been used to predict tensile property inhomogeneity in large 7010 forgings with known cooling rates. (C) 2001 Elsevier Science B.V. All rights reserved.; Accepted; peer-reviewed

The magnitude of heat treatment induced residual stresses and the thermal stress relief of aluminium alloys

Robinson, J.S; Tanner, D.A
Fonte: Trans Tech Publications Publicador: Trans Tech Publications
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; To produce useful strengthening, precipitation hardenable aluminium alloys rely on rapid quenching from the solution heat treatment temperature to suppress the formation of coarse equilibrium second phases. An unavoidable consequence of the rapid quenching of thick sections is the severe thermal gradients that quickly develop in the material. The attendant inhomogeneous plastic flow can then result in the establishment of residual stresses. Established procedures exist to minimise residual stress by quenching into boiling water or organic quenchants at the expense of ageing response. Residual stresses can also be relieved after solution heat treatment by the application of plastic deformation in a controlled manner. A limited degree of thermal stress relief is also reported to occur during subsequent artificial ageing treatments, especially duplex ageing treatments. It is generally accepted that the size of the residual stresses induced during quenching cannot exceed the yield strength of the material. However, for precipitation hardened aluminium alloys, stress magnitudes as measured by standard techniques can exceed the uniaxial stress required to cause plastic flow during tensile tests conducted immediately after quenching. An investigation to explain these observations involving measuring as-quenched tensile properties and room temperature stress relief in heat treatable and non-heat treatable aluminium alloys has been conducted. Two alloys were investigated: 7010...

Residual stress development and relief in high strength aluminium alloys using standard and retrogression thermal treatments

Robinson, J.S; Tanner, D.A
Fonte: Maney Publishing Publicador: Maney Publishing
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Residual stresses develop in the aluminium alloy 7010 when the material is quenched from the solution heat treatment temperature. Residual stress measurements have been made using the X-ray diffraction technique and a longitudinal split sawcut method to determine the magnitude of residual stress that develops in specimens sectioned from large open die forgings as a result of (a) quenching these specimens into water at different temperatures, and (b) cold water quenching from different furnace temperatures. Residual stress reductions as a result of retrogression and reaging and standard thermal treatments have been determined. The longitudinal split sawcut technique is used to demonstrate the viability of a cheap, rapid technique for determining surface stress magnitudes in specimens of suitable geometry. The variation in room temperature tensile properties of 7010 with natural aging time has also been determined. The surface residual stress magnitudes can significantly exceed the as quenched materials uniaxial limit of proportionality.; Accepted; peer-reviewed

Modelling stress reduction techniques of cold compression and stretching in wrought aluminium alloy products

Tanner, D.A; Robinson, J.S
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Heat treatable aluminium alloy aerospace products undergo a rapid quench from the solution heat treatment temperature into water/organic quenchant/spray quenching system during processing. As a result of this rapid quenching operation, residual stresses of yield strength magnitude can develop, leaving the material in an unsuitable condition for further machining operations and for service. Rectilinear, open-die forgings are generally cold compressed after quenching to relieve residual stresses. The effect of friction during cold compression between the forging and the steel compression platens, increasing/decreasing the amount of cold compression plastic deformation, natural ageing prior to cold compression, cold compression direction (LT v L v ST) and applying cold compression in 'bites' on residual stress magnitudes is not generally available. Residual stress development during quenching is modelled using the finite element technique and the effect on the final residual stress magnitude of varying these process parameters is evaluated. The effect of stretching to relieve residual stresses and the effect on residual stress magnitudes of sectioning samples of the material is also analysed using the finite element technique. The models of each of the stress relieving techniques are compared both by observing stress magnitudes and by using the FE model to predict the results from a layer removal technique. (C) 2002 Elsevier Science B.V. All rights reserved.; Accepted; peer-reviewed

Characterisation of ferritic stainless steel by Barkhausen techniques

O'Sullivan, D; Cotterell, M; Mészáros, I; Tanner, D.A
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Magneto-acoustic emission (MAE) and magnetic Barkhausen noise (MBN) sensing techniques were developed and employed to characterise plastically deformed and heat-treated AISI 430 ferritic stainless steel samples. These results have been compared to the mechanical hardness, coercivity and residual stress of the samples. MAE and MBN were shown to decrease with increasing permanent material deformation. It was found that the inverse of MAE (absolute energy) and MBN (RMS) are linearly proportional to hardness. With increased deformation, the resultant change in dislocation density was found to effect material coercivity. It has been shown that the inverse of MAE absolute energy and MBN have an exponential relationship to the change in material coercivity. The results are explained in terms of the different mechanisms that effect dislocation-domain wall interactions. A new measurement parameter has been developed for microstructural characterisation called MAE absolute energy and has proved to be a useful quantitative method in MAE waveform measurement. (C) 2004 Elsevier Ltd. All rights reserved.; Accepted; peer-reviewed

Magneto-acoustic emission for the characterisation of ferritic stainless steel microstructural state

O'Sullivan, D; Cotterell, M; Cassidy, S; Tanner, D.A; Mészáros, I
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; The role of residual stresses in the failure of metallic components and the need to determine such stresses is well recognised. Magneto-acoustic emission (MAE) is a relatively new non-destructive detection technique and its working principle is based on Barkhausen discontinuities or noise and magnetostriction when a ferromagnetic material is subjected to a varying magnetic field. MAE is being used to characterise the stress state of a ferritic stainless steel (AISI 430). Other stress measurement techniques; X-ray diffraction (XRD), magnetic Barkhausen noise (MBN) have also been used to support the results achieved using MAE. A new measurement parameter has been developed for microstructural characterisation called MAE absolute energy and has proved to be a useful quantitative method in MAE waveform measurement. (C) 2003 Elsevier B.V. All rights reserved.; Accepted; peer-reviewed

Effect of precipitation during quenching on the mechanical properties of the aluminium alloy 7010 in the W-temper

Tanner, D.A; Robinson, J.S
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Residual stress magnitudes in quenched high-strength aluminium alloys determined by several researchers using a variety of techniques indicate values that far exceed the as measured yield strength of the material in the quenched condition. Some research has indicated that the high residual stress magnitudes in large forgings may partly occur as a result of precipitation during the quench. To investigate this theory, a novel Jominy end quench technique is used to determine the hardness of aluminium alloy 7010 as a function of cooling rate. Cooling curves have been measured for Jominy end quench type samples using deeply buried thermocouples and are compared with finite element model predictions. Tensile properties are also determined for samples quenched into boiling water and compared with samples quenched into cold water. Vickers hardness and X-ray diffraction residual stress measurements are undertaken on samples of varying size acting as a comparison with the Jominy results to indicate how both homogenous and heterogeneous precipitation lead to increased as quenched mechanical strengths. (C) 2004 Elsevier B.V. All rights reserved.; accepted; peer-reviewed

Quench factor analysis of aluminium alloys using the Jominy End Quench technique

Dolan, G.P; Flynn, R.J; Tanner, D.A; Robinson, J.S
Fonte: Maney Publishing Publicador: Maney Publishing
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Determination of the time-temperature property C curve for aluminium alloys usually involves a large number of quenches and isothermal holds to calibrate a set of constants that describes the shape of the C curve for a particular property. The authors have used the Jominy end quench test to minimise the amount of work required for this type of analysis. By matching the Vickers hardness at regular intervals along the length of the Jominy test specimen with cooling curves generated using finite element analysis. (FEA),the constants of the C curve equation were determined using a single Jominy test specimen. It was possible to successfully predict the hardness down to 65% of the maximum achievable hardness with a maximum error of only 2.4%.; Accepted; peer-reviewed

The antibacterial effects of zinc ion migration from zinc-based glass polyalkenoate cements

Boyd, D; Li, H; Tanner, D.A; Towler, M.R; Wall, J.G
Fonte: Springer Publicador: Springer
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Zinc-based glass polyalkenoate cements have been synthesised and their potential use in orthopaedic applications investigated. Zinc ions were released from the materials in a rapid burst over the first 24 h after synthesis, with the release rate falling below detectable levels after 7 days. Cement-implanted bone samples were prepared and the released zinc was shown, using energy dispersive X-ray analysis, to penetrate from the cement into the adjacent bone by up to 40 mu m. Finally, the cements exhibited antibacterial activity against Streptococcus mutans and Actinomyces viscosus that reflected the pattern of zinc release, with the inhibition of growth greatest shortly after cement synthesis and little or no inhibition measureable after 30 days.; accepted; peer-reviewed

Focused ion beam assisted analysis of the oxidation of a NiAl coating on pure Ni

Reid, M; Pomeroy, Michael J.; Vokal, V; Tanner, D.A
Fonte: Maney Publishing Publicador: Maney Publishing
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Discs of (pure nickel 15 mm diameter and 4 nun thickness) have been polished to a 1 mu m finish, aluminised using a standard pack CVD process to give a beta-NiAl coating and then the surface of this coating polished to a 1 mu m finish again. Samples have then been isothermally oxidised in a muffle furnace for 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 and 1024 hours at 950 degrees C, and subjected to surface and cross-sectional microscopy and analysis. Scales were also cross-sectioned and imaged using Focused Ion Beam Milling. The oxidation rate was determined to be 2.6 x 10(-13) g(2) cm(-4) s(-1) and for times less than 512 hours the predominant alumina phase was theta alumina. Al depletion effects were observed due to both oxidation and interdiffusion between the Ni substrate and the NiAl coating. Using these effects, it has been shown that tensile strains of up to 9% can arise and these strains readily explain the formation of intrefacial elliptical pores observed by FIB cross sectioning. FIB sectioning also indicated that different coating grains exhibit different oxide-coating interfaces which arise due to different grain orientations. The faceting of the coating-oxide interface and the development of cuboidal faceted coating structures beneath spalled oxide is thought to be due to substructure development (sub-grain development or recrystallisation) arising from the plastic strains generated by Al depletion effects.; Accepted; peer-reviewed

Precipitation in vanadium bearing ultralow carbon strip steels

Ooi, S.W; Fourlais, G; Tanner, D.A; Robinson, J.S
Fonte: Maney Publishing Publicador: Maney Publishing
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; Two novel ultralow carbon (ULC) steels were investigated, one based on combined vanadium and titanium additions and the second based on titanium only additions. Grain size and mechanical property measurements have been performed on continuously annealed specimens previously subjected to 80% cold rolling reduction on both strip steel grades. The recrystallisation and grain coarsening characteristics of annealed ULC strips have been studied. The amount of precipitated species, under equilibrium conditions, at various annealing temperatures has also been calculated using MT-DATA thermodynamic modelling software. Transmission electron microscopy characterisation coupled with EDX study of the precipitation sequences on continuous annealing strips was also performed. Precipitate studies of the novel ULC steels confirmed the major role of TiC precipitates in retarding the recrystallisation behaviour of ULC strip steels. The role of vanadium addition in ULC steel grades in reducing the recrystallisation temperature of ULC strip steels was also identified.; accepted; peer-reviewed

Quantitative TEM analysis of a hexagonal mesoporous silicate structure

Hudson, Sarah; Tanner, D.A; Redington, W; Magner, Edmond; Hodnett, Benjamin K; Nakahara, S
Fonte: Royal Society of Chemistry Publicador: Royal Society of Chemistry
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; TEM analysis of mesoporous materials is generally undertaken to give qualitative results. Accurate quantitative analysis is demonstrated in this study. A systematic image analysis of a powder form of a hexagonal mesoporous material known as KIT-6 is conducted using a transmission electron microscope (TEM). Three types of image contrast typically appear in this material (a hexagonal honeycomb structure, wide and narrow parallel lines). The honeycomb face is used to characterise this material in terms of a conventional 2-D hexagonal structure and the d-spacings for the (100) and (110) planes are experimentally measured in varying focus conditions. A tilting experiment is conducted to determine how the angle of tilt affects the line spacing and their visibility. Tilting has very little effect on the line spacing, whereas it affects the visibility of both the wide and narrow lines by limiting an angle range of visibility. The hexagonal lattice structure parameter determined by TEM method is found to be similar to 7% lower than that calculated by low-angle X-ray diffraction. Thus we conclude that TEM data can be used to determine the geometry and dimensions of hexagonal mesoporous silica materials, with a small error in the hexagonal lattice parameter.; Accepted; peer-reviewed

The influence of aluminium alloy quench sensitivity on the magnitude of heat treatment induced residual stress

Robinson, J.S; Tanner, D.A
Fonte: Trans Tech Publications Publicador: Trans Tech Publications
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
Português
peer-reviewed; To produce useful strengthening, precipitation hardenable aluminium alloys rely on rapid quenching from the solution heat treatment temperature to suppress the fort-nation of coarse equilibrium second phases. An unavoidable consequence of the rapid quenching of thick sections is the severe thermal gradients that quickly develop in the material. The attendant inhomogeneous plastic flow can then result in the establishment of residual stresses. The surface and through thickness residual stress magnitudes present in heat treated high strength aluminium alloy components are frequently reported to exceed the uniaxial yield stress of small specimens of the same alloy measured immediately after quenching. In thick section plate and forgings it is proposed that these high residual stress magnitudes are a consequence of hardening precipitation that occurs during quenching which allows for a greater elastic stress to be supported. To investigate this theory, thick sections of the quench sensitive alloy 7175 and the less quench sensitive alloy 7010 were heat treated in such a way as to allow the internal hardness to be measured immediately, after quenching. The rate of cooling was also monitored during quenching and these data were used in conjunction with time temperature property data to predict the degree of precipitation and subsequent loss of hardening potential in the fully heat treated condition. The magnitudes of the residual stresses induced during quenching were determined using standard x-ray diffraction techniques.; PUBLISHED; peer-reviewed

Ultrasonically set glass polyalkenoate cements for orthodontic applications

Tanner, D.A; Rushe, N; Towler, M.R
Fonte: University of Limerick Publicador: University of Limerick
Tipo: Article (peer-reviewed)
Português
There is an accepted clinical requirement for a luting cement that can be command set upon satisfactory placement of an orthodontic appliance onto dentition. This work evaluates the suitability of ultrasound, imparted from a dental scaler, as a potential mechanism for achieving this. The net setting times and subsequent compressive strengths of a range of commercial and experimental glass polyalkenoate cements (GPCs) were evaluated, using modified ISO 9917 methods, when set both chemically and by ultrasound. The ultrasound was applied to the GPC through an orthodontic brace. It was possible to command set GPCs by the application of five to ten seconds of ultrasound; the exact time required being dependent upon the composition of the GPC in question. The compressive strengths of these cements can be improved by around 90% with the command set when the optimum PAA molecular weight and tartaric acid content is employed.; accepted; peer-reviewed