Virtual Testing Architecture for Prediction of Effective Properties of Particulate Composites

This study has developed a computational virtual testing architecture for predicting effective properties of particulate composites. A particulate composite made up of SiC filler in an alumina matrix was used in this work. The test composite was modelled first by considering perfect bonding between the matrix and filler constituents and subsequently the effect of interphase region was assessed too

Ill-posedness of degenerate dispersive equations

In this article we provide numerical and analytical evidence that some degenerate dispersive partial differential equations are ill-posed. Specifically we study the K(2,2) equation $u_t = (u^2)_{xxx} + (u^2)_{x}$ and the "degenerate Airy" equation $u_t = 2 u u_{xxx}$. For K(2,2) our results are computational in nature: we conduct a series of numerical simulations which demonstrate that data which is very small in $H^2$ can be of unit size at a fixed time which is independent of the data's size. For the degenerate Airy equation, our results are fully rigorous: we prove the existence of a compactly supported self-similar solution which, when combined with certain scaling invariances, implies ill-posedness (also in $H^2$)

A constitutive model for semi-crystalline polymers: A multiple viscoelastic relaxation processes implementation.

The constitutive modelling of semi-crystalline polymers seeks to obtain reliable predictive tools for a wide range of their mechanical responses. Such efforts have continued to occupy computational material scientists. Although significant advances have been made regarding amorphous polymers, thanks to works by Buckley [1], Boyce [2], and Govaert [3], there is significant research scope for developing similar predictive modelling fidelity for semi-crystalline polymers. The presence of crystalline and amorphous phases in semi-crystalline polymers presents interesting constitutive modelling challenges. In this study, a physically based, three-dimensional constitutive model has been developed for simulating a wide range of features observed in deformation and processing of semi-crystalline polymers. The constitutive mathematics is based on a one-process Grass-Rubber model for amorphous polymers proposed by Buckley and colleagues [1]. The model philosophy exploits the presence of multiple relaxation processes associated with the different mechanics of the crystalline, amorphous and pseudo-amorphous parts of the polymer. The model development reasoning is inspired by a well-known physical framework of rate-dependent deformation that establishes a correlation between the observed transition in flow stress of a material and the secondary β-transition of the viscoelastic behaviour. Here, two dominant relaxation processes were identified - the α- and the β-processes. Each process was modelled using the bond-stretching and conformational stresses constitutive mathematics of the Glass-Rubber model. The model has been implemented numerically into a commercial finite element code through a user-defined material subroutine (UMAT) and validated against compression test results carried out on an isotactic polypropylene across an unusually wide range of strain rates [4]. In this study, the model predicts quite well the experimentally observed nonlinear mechanical responses like: temperature and rate-dependence, adiabatic heating effects, structural rejuvenation and post-yield de-ageing of polypropylene. It provides a viable modelling tool that can be utilized for design involving semicrystalline polymers at room temperature as well as exploring the processing response at elevated temperatures

Effects of Na2Cr2O7 Inhibitor on the Corrosion Potential Response of Steel Reinforced Concrete in Saline Medium

Electrochemical monitoring method of the open circuit potential was used to investigate the effect of the concentrations of Na2Cr2O7 on the corrosion potential response of steel reinforced concrete in sodium chloride medium. In the study, five different concentrations of Na2Cr2O7 admixtures were employed in a system of replicated samples of steel-reinforced concrete specimens partially immersed in 3.5% NaCl to simulate marine and saline environments. Forty days measured responses from these were subjected to the statistical analyses of the Normal and the Weibull distribution functions and tested using the Kolmogorov-Smirnov goodness of fit criteria. Results obtained from the analyses identified 4 g Na2Cr2O7 with optimal averaged potential response inhibition performance by the Normal model which showed better agreements in its models of Na2Cr2O7 potential test data than that obtained from the Weibull model of the same data. These bear pertinent implications on the need for suitability studies of appropriate statistical distribution for studying performance of corrosion inhibitors even as suggestions were proffered for addressing results conflicts among replicates of steel reinforced concrete samples employed

Cohousing for older people: Housing innovation in the Netherlands and Denmark

Objective: The aim of this paper is to elucidate cohousing for older people. Method: The research is based on a literature review and interviews (in English) with residents of seven schemes in the Netherlands and Denmark, a social housing organisation and several researchers in the field (in 1995 and 2002). Results and Conclusions: Cohousing for older people is now well established in its countries of origin - Denmark and the Netherlands - as a way for older people to live in their own house or unit, with a self-chosen group of other older people as neighbours, with shared space and facilities they collectively determine or control. As more such housing is built and occupied it has become easier to choose and assess this option. It remains to be seen how widespread its appeal will be, but cohousing for older people is now a valued housing niche

Accessible tourism futures: the world we dream to live in and the opportunities we hope to have

© 2015, Eleni Michopoulou, Simon Darcy, Ivor Ambrose and Dimitros Buhalis. PurposeAccessible tourism is evolving as a field of academic research and industry practice, set within a dynamic social context. The field is interdisciplinary, multidisciplinary and transdisciplinary. The purpose of this paper is to examine key concepts and global initiatives that will shape accessible tourism futures. Design/methodology/approachThree of the authors have extensive academic experience in the area and the fourth author is the Managing Director of the pre-eminent European Network for Accessible Tourism. In taking a limited Delphi approach to canvassing key areas likely to shape accessible tourism futures, the following concepts and policy initiatives were examined: motivations, dreams and aspirations of people with disability; demography; UN Convention on the Rights of Persons with Disabilities; destination competitiveness; universal design (UD); and the UN Sustainable Development Goals for 2030. FindingsA discussion of each of the above areas was placed in context to accessible tourism futures and to contextualise the papers that were selected for the special issue. The latter part of the paper outlines the contribution of each empirical paper to the issue discussing the approach, findings and implications. Stakeholder collaboration was identified as the key common theme of the papers and the factor for developing accessible tourism solutions, recognising the value of the market and capitalising on it. A collaborative approach is required to recognise the complementary nature of the different paradigms; to re-shape and transform the future of the accessible tourism industry. To assist in the development of accessible tourism futures, UD principles should provide a foundation to enhance the future competitiveness of tourism destinations and organisations. Originality/valueThe paper’s examination of the concepts and global policy considerations provides a strong academic and practitioner foundation for considering accessible tourism futures. In doing so, accessible tourism futures are shown to be affected by key concepts related to core tourism considerations and major policy initiatives on accessibility and sustainability. Yet, accessible tourism futures also have the potential to create their own momentum and contribute unique learnings on the diversity of tourism markets that will shape tourism concepts and global policy initiatives in their own right

Compressive strength and workability of laterized quarry sand concrete

This paper presents an experimental study on workability and compressive strength of concrete using various combinations of lateritic sand and quarry sand as complete replacement for conventional river sand fine aggregate. Quantity of lateritic sand varied from 0 to 50% against quarry dust at interval of 10%. Concrete cubes were prepared for two mix ratios: 1:1.5:3 and 1:2:4 and three water/cement ratios: 0.5, 0.6 and 0.7 and were cured and tested in the laboratory for compressive strength. Slump tests were also carried out for each mix. For each mix and water/cement ratios, control samples were also prepared using river sand as fine aggregate. The resulting concrete cubes fall within the range for normal weight concrete and although laterized quarry dust concrete had poorer workability, their compressive strength compare favourably with those of conventional concrete. The use of laterized quarry sand concrete for structural members is therefore recommended when laterite content is not more than 50%.Keywords: Compressive Strength, Concrete, Lateritic Sand, Quarry Sand, Workabilit

Two-process constitutive model for semicrystalline polymers across a wide range of strain rates

The presence of crystalline and amorphous phases in semicrystalline polymers presents interesting constitutive modelling challenges. In this study, a physically based, three-dimensional constitutive model has been developed for simulating a wide range of features observed in deformation and processing of semicrystalline polymers. The proposed model combines into one constitutive model such features as: multiple viscoelastic relaxation processes, very wide strain-rate range, temperature-dependence, adiabatic heating, structural rejuvenation; in addition to it being applied to a semicrystalline polymer. The constitutive mathematics is based on a one-process glass-rubber model for amorphous polymers. It adapts that model to semicrystalline polymers by extending it to two relaxation processes: one associated with the glass transition of the mobile amorphous phase; the other associated with relaxation of the crystalline fraction and its associated rigid amorphous phase. In particular, two dominant processes were identified: the α-process and the β-process. The model has been implemented numerically into a commercial finite element code through a user-defined material subroutine (UMAT). The model has been validated against compression test results carried out on polypropylene. Also, the model predicts very well the experimentally observed nonlinear rate-dependent response and post-yield de-ageing of polypropylene

Rare Kaon Decays

The current status of rare kaon decay experiments is reviewed. New limits in the search for Lepton Flavor Violation are discussed, as are new measurements of the CKM matrix.Comment: 8 pages, 3 figures, LaTeX, presented at the 3rd International Conference on B Phyiscs and CP Violation, Taipei December 3-7, 199