Towards a harmonised European bond test

Bond influences several aspects of structural performance. Standard methods of bond test currently specified were developed over 30 years ago. During this time understanding of the phenomenon of bond between reinforcement and concrete and of the factors which influence it has expanded greatly. An overview of the current knowledge and needs demonstrates that a reappraisal of standard bond tests is now necessary. The paper outlines the principals that should underpin a bond test specification derived from considerations of the manner in which bond influences structural performance. It is demonstrated that a single measure of performance is inadequate, and develops proposals for a system of testing in which several measures can be used to classify each aspect of structural performance. A development length form of test with the bar in tension is selected, with low confinement from concrete cover and transverse reinforcement. The proposal is developed to a conceptual stage in the present paper. Following consultation with interested parties, the Authors propose to develop a detailed specification.

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Résumé L'adhérence entre le béton et l'armature influence bien des aspects du comportement structurel, au point que l'on a développé beaucoup des méthodes standardisées pour la mesure de l'adhérence pendant ces trente dernières années. En même temps, l'intelligence de la nature de l'adhérence entre le béton et l'armature, et des facteurs qui l'influencent, a fait d'extraordinaires pas en avant: une réflexion sur l'état des connaissances et sur les nécessités de développement montre qu'un revirement au sujet des essais standardisés sur l'adhérence ne peut être différé. Dans ce contexte, on présente ici les principes sur lesquels on devrait fonder les spécifications pour les essais sur l'adhérence, compte tenu des effets qu'elle a sur le comportement structurel. On montre qu'une unique mesure des performances est insuffisante, et que le développement d'un système d'essais, avec la possibilité de mesurer plusieurs performances structurelles de l'adhérence et de les classer, est désormais nécessaire. On propose un essai basé sur le même principe que celui qui gouverne les essais concernant le bout terminal d'une poutre fléchie (beam-end test), avec un confinement relativement bas, exercé par le recouvrement en béton et par les étriers.

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Towards a new generic framework for citation network generation and analysis in the humanities

Scientometrics - Citation network analysis is one of the most developed techniques in science mapping. Various types of citation analysis have been proposed in the literature such as direct...     

Towards a multi-physics modelling framework for thrombolysis under the influence of blood flow

Thrombolytic therapy is an effective means of treating thromboembolic diseases but can also give rise to life-threatening side effects. The infusion of a high drug concentration can provoke internal bleeding while an insufficient dose can lead to artery reocclusion. It is hoped that mathematical modelling of the process of clot lysis can lead to a better understanding and improvement of thrombolytic therapy. To this end, a multi-physics continuum model has been developed to simulate the dissolution of clot over time upon the addition of tissue plasminogen activator (tPA). The transport of tPA and other lytic proteins is modelled by a set of reaction–diffusion–convection equations, while blood flow is described by volume-averaged continuity and momentum equations. The clot is modelled as a fibrous porous medium with its properties being determined as a function of the fibrin fibre radius and voidage of the clot. A unique feature of the model is that it is capable of simulating the entire lytic process from the initial phase of lysis of an occlusive thrombus (diffusion-limited transport), the process of recanalization, to post-canalization thrombolysis under the influence of convective blood flow. The model has been used to examine the dissolution of a fully occluding clot in a simplified artery at different pressure drops. Our predicted lytic front velocities during the initial stage of lysis agree well with experimental and computational results reported by others. Following canalization, clot lysis patterns are strongly influenced by local flow patterns, which are symmetric at low pressure drops, but asymmetric at higher pressure drops, which give rise to larger recirculation regions and extended areas of intense drug accumulation.     

Towards improved empirical isobase models of Holocene land uplift for mainland Scotland, UK

A new approach to modelling patterns of glacio-isostatic land uplift during the Holocene in mainland Scotland, UK, is described. The approach is based upon altitude measurements at the inner margin or locally highest point of raised estuarine surfaces dated by radiocarbon assay supported by microfossil analyses. 2,241 altitudes have been analysed by a technique new to studies of former sea-levels, Gaussian Trend Surface Analysis, and isobase models for four Holocene shorelines: the Holocene Storegga Slide tsunami shoreline, abandoned rapidly circa 7,900 sidereal years BP; the Main Postglacial shoreline, abandoned during circa 6,400-7,700 sidereal years BP; the Blairdrummond shoreline, abandoned during circa 4,500-5,800 sidereal years BP, and a speculative fourth shoreline, the Wigtown shoreline, abandoned during circa 1,520-3,700 sidereal years BP, are shown in a series of maps. The implications of the shoreline patterns for glaicio-isostasy in the area are discussed. It is maintained that the statistical technique used enables broad estimates to be made of near shore sea surface change.     

Towards a vulnerability assessment of the UK and northern European coasts: the role of regional climate variability

Within the framework of a Tyndall Centre research project, sea level and wave changes around the UK and in the North Sea have been analysed. This paper integrates the results of this project. Many aspects of the contribution of the North Atlantic Oscillation (NAO) to sea level and wave height have been resolved. The NAO is a major forcing parameter for sea-level variability. Strong positive response to increasing NAO was observed in the shallow parts of the North Sea, while slightly negative response was found in the southwest part of the UK. The cause of the strong positive response is mainly the increased westerly winds. The NAO increase during the last decades has affected both the mean sea level and the extreme sea levels in the North Sea. The derived spatial distribution of the NAO-related variability of sea level allows the development of scenarios for future sea level and wave height in the region. Because the response of sea level to the NAO is found to be variable in time across all frequency bands, there is some inherent uncertainty in the use of the empirical relationships to develop scenarios of future sea level. Nevertheless, as it remains uncertain whether the multi-decadal NAO variability is related to climate change, the use of the empirical relationships in developing scenarios is justified. The resulting scenarios demonstrate: (i) that the use of regional estimates of sea level increase the projected range of sea-level change by 50% and (ii) that the contribution of the NAO to winter sea-level variability increases the range of uncertainty by a further 10-20cm. On the assumption that the general circulation models have some skill in simulating the future NAO change, then the NAO contribution to sea-level change around the UK is expected to be very small (<4cm) by 2080. Wave heights are also sensitive to the NAO changes, especially in the western coasts of the UK. Under the same scenarios for future NAO changes, the projected significant wave-height changes in the northeast Atlantic will exceed 0.4m. In addition, wave-direction changes of around 20 degrees per unit NAO index have been documented for one location. Such changes raise the possibility of consequential alteration of coastal erosion.     

Nanotechnological medical devices and nanopharmaceuticals: the European regulatory framework and research needs

The European regulatory framework is examined in relation to nanotechnology based medical devices and medicinal products. Medical applications of nanotechnology will have to comply with the requirement for a high level of public health, safety, consumer, and environmental protection. An evaluation of the possible health or environmental risks of nanoparticles must therefore be carried out and it is important to ensure that particle size and chemistry are taken into account when investigating possible adverse effects. Further research is needed on the toxicological and ecotoxicological properties of nanoparticles, their uptake in the body, accumulation in tissues and organs, transport characteristics, exposure and dose-response data, and their distribution and persistence in the environment. The existing regulations appear adequate to manage the risks of nanotechnology at its current stage of development but continuous review of the regulatory regime will be needed to determine whether it is sufficient to protect human health and the environment. Modification of the legislation may prove necessary as new scientific evidence emerges regarding the effects of nanoparticles on living organisms and in the ecosystems.     

Towards a European economics of economics: Monitoring a decade of top research and providing some explanation

Summary This study documents a decade of mainstream research output by European economics institutions. In contrast to previous European economics departmental rankings, we investigate the changing pattern of the ranking over two subperiods and a total decade. The validity of our bibliometric approach is demonstrated by a comparison with gradings of UK economic departments in the 2001 Research Assessment Exercise (RAE). We also provide some explanation of the ranking based on regional factors and institutional features. Strong evidence for the 'institutional oligopoly' of editors and authors hypothesis is found. However, in a dynamic context this departmental concentration of authorship and editorial board membership does not represent a 'closed shop'. We find several departments entering the centre stage of economic mainstream for the first time towards the end of the 1990s.     

Towards a catastrophe theory for the mechanics of plasticity and fracture

The catastrophe theory has established that the conservative systems have only a few ways to lose their stability. We sketch a similar classification for a class of dissipative systems. Although our scope is limited to the case of two dissipative variables, we find six elementary catastrophes. We present examples from discrete plasticity, crack and friction mechanics.     

Towards a model for diachronous and synchronous citation analyses

This paper gives an overview of the diachronous (prospective) and synchronous (retrospective) approach to ageing studies of scientific literature from the perspective of technical reliability, visualising the different aspects that can be analysed by the two approaches. The main objective is to deepen the understanding of the mechanism and the theory underlying the two aproaches, and is to show that the difference between the diachronous and synchronous model is not “just counting into opposite directions”. In this context, a stochastic model is presented showing that one and the same model can be used to describe both diachronous and synchronous perspectives of citation processes. On the basis of this model, it is explained how some diachronous and synchronous citation-based indicators can be re-calculated for changing publication periods and citation windows underlying their construction. The paper is concluded by several applications such as the definition and calculation of diachronous (prospective) and synchronous (retrospective) journal impact measures and other citation indicators used in research evaluation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Towards a universal dissolution medium for carbamazepine

The aim of this study was to develop a dissolution medium for assessment of various carbamazepine (CBZ) formulations with different strengths. The design of a system inhibiting transformation of the anhydrous CBZ (CBZ A) to the dihydrate form (CBZ D), with minimum surface-active properties and suitable sink was investigated. The effect of pH, different concentrations of sodium lauryl sulphate (SLS), polyvinylpyrrolidone (PVP), and methyl cellulose (MC) on dissolution rate, solubility, dissolution solubility, and polymorphic transformation of CBZ was assessed. Solution-mediated transformation of CBZ A into CBZ D was monitored using optical microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. Results showed that different strengths (100, 200, 400 mg) of the same CBZ tablet formulation exhibited different dissolution patterns, in 1% SLS (USP system). Such differences were reduced in 0.5% SLS solution which provided sufficient sink for up to 200 mg CBZ. It was also shown that solubility of CBZ A could not be detected in the media under study (water, SGF, SIF, and SLS solutions) due to its rapid transformation into CBZ D. The use of 3% PVP solution protected CBZ A from conversion for 75 min, while 0.01% MC completely inhibited the transformation up to 24 h. Therefore, a medium consisting of 0.5% SLS and 0.01% MC was selected. The medium provided: a) protection against transformation of CBZ A to CBZ D, b) increased solubility of CBZ A (204 mg % compared to 128 mg % of CBZ D in 0.5% SLS), c) suitable sink for up to 400 mg CBZ and d) overlapping dissolution profiles of various strengths of the same CBZ formulation. The suggested system may be a step in the way of solving CBZ dissolution problems that forced the USP to specify two similar dissolution tests with two different limits for conventional 200 mg CBZ tablets.     

Towards a Universal Dissolution Medium for Carbamazepine

ABSTRACT

The aim of this study was to develop a dissolution medium for assessment of various carbamazepine (CBZ) formulations with different strengths. The design of a system inhibiting transformation of the anhydrous CBZ (CBZ A) to the dihydrate form (CBZ D), with minimum surface-active properties and suitable sink was investigated. The effect of pH, different concentrations of sodium lauryl sulphate (SLS), polyvinylpyrrolidone (PVP), and methyl cellulose (MC) on dissolution rate, solubility, dissolution solubility, and polymorphic transformation of CBZ was assessed. Solution-mediated transformation of CBZ A into CBZ D was monitored using optical microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. Results showed that different strengths (100, 200, 400 mg) of the same CBZ tablet formulation exhibited different dissolution patterns, in 1% SLS (USP system). Such differences were reduced in 0.5% SLS solution which provided sufficient sink for up to 200 mg CBZ. It was also shown that solubility of CBZ A could not be detected in the media under study (water, SGF, SIF, and SLS solutions) due to its rapid transformation into CBZ D. The use of 3% PVP solution protected CBZ A from conversion for 75 min, while 0.01% MC completely inhibited the transformation up to 24 h. Therefore, a medium consisting of 0.5% SLS and 0.01% MC was selected. The medium provided: a) protection against transformation of CBZ A to CBZ D, b) increased solubility of CBZ A (204 mg % compared to 128 mg % of CBZ D in 0.5% SLS), c) suitable sink for up to 400 mg CBZ and d) overlapping dissolution profiles of various strengths of the same CBZ formulation. The suggested system may be a step in the way of solving CBZ dissolution problems that forced the USP to specify two similar dissolution tests with two different limits for conventional 200 mg CBZ tablets.     

Applying a reusable framework for software selection

With increasing use of component-based development (CBD), the process for selecting software from repositories is a critical concern for quality systems development. As support for developers blending in-house and third party software, the context-driven component evaluation (CdCE) process provides a three-phase approach to software selection: filtering to a short list, functional evaluation and ranking. The process was developed through iterative experimentation on real-world data. CdCE has tool support to generate classifier models, shortlists and test cases as artefacts that provide for a repeatable, transparent process that can be reused as the system evolves. Although developed for software component selection, the CdCE process framework can be easily modified for other selection tasks by substituting templates, tools, evaluation criteria and/or repositories. In this article the authors describe the CdCE process and its development, the CdCE framework as a reusable pattern for software selection and provide a case study where the process is applied.     

Towards a fracture mechanics for brittle piezoelectric and dielectric materials

A theoretical fracture mechanics for brittle piezoelectric and dielectric materials is developed consistent with standard features of elasticity and dielectricity. The influence of electric field and mechanical loading is considered in this approach and a Griffith style energy balance is used to establish the relevant energy release rates. Results are given for a finite crack in an infinite isotropic dielectric and for steady state cracking in a piezoelectric strip. In the latter problem, the effect of charge separation in the material and discharge in the crack are considered. Observations of crack behavior in piezoelectrics under combined mechanical and electrical load are discussed to assess which features of the theory are useful.     

Towards a lessons learned system for critical software

Failure can be a major driver for the advance of any engineering discipline and Software Engineering is no exception. But failures are useful only if lessons are learned from them. In this article we aim to make a strong defence of, and set the requirements for, lessons learned systems for safety-critical software. We also present a prototype lessons learned system that includes many of the features discussed here. We emphasize that, apart from individual organizations, lessons learned systems should target industrial sectors and even the Software Engineering community. We would like to encourage the Software Engineering community to use this kind of systems as another tool in the toolbox, which complements or enhances other approaches like, for example, standards and checklists.