199 research outputs found

    Record of stranded whales along Karnataka coast

    Get PDF
    A whale was stranded in the beach of Guijerbettu, Udupi district, Karnataka on 21.12.2001 . The whale was found in live condition. Thelocal person tried to rescue it but was in vain and later it died. The whale was identified as Balaenopteramusculus (Blue whale). Few vertebrae have been collected and preserved in the museum of Mangalore Research Centre of CMFRI for future identification up to the species level. Another whale (genus : Balaenoptera) was stranded in Kota, Udupi district, Karnataka near the shore of Arama temple on 11.08.2004 in decayed condition

    Fracture Response of Metallic Particulate-reinforced Cementitious Composites: Insights from Experiments and Multiscale Numerical Simulations

    Get PDF
    This paper presents an experimental and numerical investigation into the fracture response of mortars containing up to 30% waste iron powder by volume as OPC-replacement. The iron powder-modified mortars demonstrate significantly improved strength and fracture properties as compared to the control mortars due to presence of elongated iron particulates in the powder. With a view to develop a predictive tool towards materials design of such particulate-reinforced systems, fracture responses of iron powder-modified mortars are simulated using a multiscale numerical approach. The approach implements multi-scale numerical homogenization involving cohesive zone-based damage at the matrix-inclusion interface and isotropic damage in the matrix to obtain composite constitutive response and fracture energy. Consequently, these results serve as input to macro-scale XFEM-based three-point-bend simulations of notched mortar beams. The simulated macroscopic fracture behavior exhibit excellent match with the experimental results. Thus, the numerical approach links the material microstructure to macroscopic fracture parameters facilitating microstructure-guided material design

    Microstructure-guided numerical simulation to evaluate the influence of phase change materials (PCMs) on the freeze-thaw response of concrete pavements

    Get PDF
    The use of phase change materials in infrastructure has gained significant attention in the recent years owing to their robust thermal performance. This study implements a numerical simulation framework using finite element analysis to evaluate the influence of phase change materials (PCMs) on the thermal response of concrete pavements in geographical regions with significant winter weather conditions. The analysis is carried out at different length scales. The latent-heat associated with different PCMs is efficiently incorporated into the simulation framework. Besides, the numerical simulation framework employs continuum damage mechanics to evaluate the influence of PCMs on the freeze-thaw induced damage in concretes. The simulations show significant reductions in the freeze-thaw induced damage when PCMs are incorporated in concrete. The numerical simulation framework, developed here, provides efficient means of optimizing the material design of such durable PCM-incorporated concretes for pavements by tailoring the composition and material microstructure to maximize performance

    Brexit writings and the war of position over migration, 'race' and class

    Get PDF
    This timely series of interventions scrutinises the centrality of race and migration to the 2016 Brexit campaign, vote and its aftermath. It brings together five individual pieces, with an accompanying introduction, which interrogate different facets of how race, migration and Brexit interconnect: an examination of the so called 'left behinds' and the fundamental intersections between geography, race and class at the heart of Brexit motivations and contexts; an exploration of arguably parallel and similarly complex developments in the US with the rise of populism and support for Donald Trump; an analysis of the role of whiteness in the experiences of East European nationals in the UK in the face of increased anti-foreigner sentiment and uncertainty about future status; a discussion of intergenerational differences in outlooks on race and immigration and the sidelining of different people and places in Brexit debates; and a studied critique of prevailing tropes about Brexit which create divisive classed and raced categories and seek to oversimplify broader understandings of race, class and migration. Taken together these articles, all arguing for the need to eschew easy answers and superficial narratives, offer important and opportune insights into what Brexit tells us about race and migration in contemporary UK

    Negotiating identities: ethnicity and social relations in a young offenders' institution

    Get PDF
    This article explores the situated nature of male prisoner identities in the late modern British context, using the contrasting theoretical frames of Sykes's (1958) indigenous model and Jacobs' (1979) importation model of prisoner subcultures and social relations. Drawing on eight months of ethnographic fieldwork in an ethnically, religiously and nationally diverse young offenders institution, consideration is given to how prisoners manage and negotiate difference, exploring the contours of racialization and racism which can operate in ambiguous and contradictory ways. Sociological understandings of identity, ethnicity, racialization and racism are used to inform a more empirically grounded theoretical criminology

    Arabian Sea high salinity core supplies oxygen to Bay of Bengal oxygen minimum zone

    Full text link
    The oxygen minimum zone (OMZ) in the Bay of Bengal (BoB) is unique owing to its curious capability to maintain steady dissolved oxygen (DO) levels. In this study, we identify a process by which the oxygen levels in BoB are sustained above the tipping point, using DO and microstructure profiles in the southern BoB and Argo profiles over the entire basin. High salinity core (HSC) rich in DO is advected by the Summer Monsoon Current (SMC) into BoB. Vertical mixing driven by turbulent and salt-fingering processes recharge DO concentration in thermocline above OMZ. HSC identified in the Argo data, also rich in oxygen, can be traced up to 19^\circ N, confirming that HSC is a source of DO and potentially prevents OMZ from moving to the denitrification regime. In changing climate conditions, this might be the only significant oxygen source for the BoB OMZ in the future

    Fracture Toughness of Fly Ash-Based Geopolymer Gels: Evaluations Using Nanoindentation Experiment and Molecular Dynamics Simulation

    Get PDF
    This paper presents the fracture toughness of sodium aluminosilicate hydrate (N-A-S-H) gel formed through alkaline activation of fly ash. While the fracture toughness of N-A-S-H is obtained experimentally from nanoindentation experiment implementing the principle of conservation of energy, the numerical investigation is performed via reactive force field molecular dynamics. A statistically significant number of indentations are performed on geopolymer paste yielding frequency distribution of Young’s modulus. Four distinct peaks are observed in the frequency distribution plot from which the peak corresponding to N-A-S-H was separated using statistical deconvolution technique. The young’s modulus of N-A-S-H, thus obtained from statistical deconvolution shows excellent match with the values reported in the literature, thus confirming successful identification of indentations corresponding to N-A-S-H. From the load-penetration depth responses of N-A-S-H, fracture toughness was obtained following the principle of conservation of energy. The experimental fracture toughness shows good correlation with the simulated fracture toughness of N-A-S-H, obtained from reactive force field molecular dynamics. The fracture toughness of N-A-S-H presented in this paper paves the way for multiscale simulation-based design of tougher geopolymer binders

    A Peridynamics-Based Micromechanical Modeling Approach for Random Heterogeneous Structural Materials

    Get PDF
    This paper presents a peridynamics-based micromechanical analysis framework that can efficiently handle material failure for random heterogeneous structural materials. In contrast to conventional continuum-based approaches, this method can handle discontinuities such as fracture without requiring supplemental mathematical relations. The framework presented here generates representative unit cells based on microstructural information on the material and assigns distinct material behavior to the constituent phases in the random heterogenous microstructures. The framework incorporates spontaneous failure initiation/propagation based on the critical stretch criterion in peridynamics and predicts effective constitutive response of the material. The current framework is applied to a metallic particulate-reinforced cementitious composite. The simulated mechanical responses show excellent match with experimental observations signifying efficacy of the peridynamics-based micromechanical framework for heterogenous composites. Thus, the multiscale peridynamics-based framework can efficiently facilitate microstructure guided material design for a large class of inclusion-modified random heterogenous materials

    Fracture Toughness of Fly Ash-Based Geopolymer Gels: Evaluations Using Nanoindentation Experiment and Molecular Dynamics Simulation

    Full text link
    This paper presents the fracture toughness of sodium aluminosilicate hydrate (N-A-S-H) gel formed through alkaline activation of fly ash. While the fracture toughness of N-A-S-H is obtained experimentally from nanoindentation experiment implementing the principle of conservation of energy, the numerical investigation is performed via reactive force field molecular dynamics. A statistically significant number of indentations are performed on geopolymer paste yielding frequency distribution of Young’s modulus. Four distinct peaks are observed in the frequency distribution plot from which the peak corresponding to N-A-S-H was separated using statistical deconvolution technique. The young’s modulus of N-A-S-H, thus obtained from statistical deconvolution shows excellent match with the values reported in the literature, thus confirming successful identification of indentations corresponding to N-A-S-H. From the load-penetration depth responses of N-A-S-H, fracture toughness was obtained following the principle of conservation of energy. The experimental fracture toughness shows good correlation with the simulated fracture toughness of N-A-S-H, obtained from reactive force field molecular dynamics. The fracture toughness of N-A-S-H presented in this paper paves the way for multiscale simulation-based design of tougher geopolymer binders

    Fracture toughness of sodium aluminosilicate hydrate (NASH) gels: Insights from molecular dynamics simulations

    Get PDF
    This paper evaluates the fracture toughness of sodium aluminosilicate hydrate (N-A-S-H) gel formed through alkaline activation of fly ash via molecular dynamics (MD) simulations. The short- and medium-range order of the constructed N-A-S-H structures shows good correlation with the experimental observations, signifying the viability of the N-A-S-H structures. The simulated fracture toughness values of N-A-S-H (0.4–0.45 MPa m0.5) appear to be of the same order as the available experimental values for fly ash-based geopolymer mortars and concretes. These results suggest the efficacy of the MD simulation toward obtaining a realistic fracture toughness of N-A-S-H, which is otherwise very challenging to obtain experimentally, and no direct experimental fracture toughness values are yet available. To further assess the fracture behavior of N-A-S-H, the number of chemical bonds formed/broken during elongation and their relative sensitivity to crack growth are evaluated. Overall, the fracture toughness of N-A-S-H presented in this paper paves the way for a multiscale simulation-based design of tougher geopolymers
    corecore