26,303 research outputs found
Nonmagnetic Impurity Resonances as a Signature of Sign-Reversal Pairing in the FeAs-based Superconductors
The low energy band structure of the FeAs based superconductors is fitted by
a tight binding model with two Fe ions per unit cell and two degenerate
orbitals per Fe ion. Based on this, superconductivity with extended s-wave
pairing symmetry of the form is examined. The local
density of states near an impurity is also investigated by using T-matrix
approach. For the nonmagnetic scattering potential, we found that there exist
two major resonances inside the gap. The height of the resonance peaks depends
on the strength of the impurity potential. These in-gap resonances are
originated in the Andreev's bound states due to the quasiparticle scattering
between the hole Fermi surfaces around point with positive order
parameter and the electron Fermi surfaces around point with negative order
parameter.Comment: 5 pages, 5 figure
Subject-specific finite element modelling of the human hand complex : muscle-driven simulations and experimental validation
This paper aims to develop and validate a subject-specific framework for modelling the human hand. This was achieved by combining medical image-based finite element modelling, individualized muscle force and kinematic measurements. Firstly, a subject-specific human hand finite element (FE) model was developed. The geometries of the phalanges, carpal bones, wrist bones, ligaments, tendons, subcutaneous tissue and skin were all included. The material properties were derived from in-vivo and in-vitro experiment results available in the literature. The boundary and loading conditions were defined based on the kinematic data and muscle forces of a specific subject captured from the in-vivo grasping tests. The predicted contact pressure and contact area were in good agreement with the in-vivo test results of the same subject, with the relative errors for the contact pressures all being below 20%. Finally, sensitivity analysis was performed to investigate the effects of important modelling parameters on the predictions. The results showed that contact pressure and area were sensitive to the material properties and muscle forces. This FE human hand model can be used to make a detailed and quantitative evaluation into biomechanical and neurophysiological aspects of human hand contact during daily perception and manipulation. The findings can be applied to the design of the bionic hands or neuro-prosthetics in the future
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Sustainable design approach underpinned with Life Cycle Impact Assessment(LCIA) and ontology
Sustainable development has been a subject of global interest when people shift the focus from the economy and productivity only to the economy with consideration of the environment and resources on the earth. Manufacturing industry is one of the most crucial sectors that people focused on to make it more sustainable. However, the sustainability for current existing products are not enough to satisfy the requirement of sustainable development within the modern society. Therefore, an approach to design and to optimise product considering ecological impact is to be developed by this research. After review and comparison of popular LCIA methods and tools, the three-tier sustainable design approach considering human labour ecological impact is developed. Design optimisation with eco-constraints using genetic algorithm is followed. Moreover, from a product life cycle point of view, production may not be the least sustainable section. Use and disposal also play important roles in the whole product life cycle. In this case, Ontology is proposed in the research. It is a powerful tool to collect and exchange data of products and manage the relationships among different parts, properties of products, and suppliers in one specific area such as a factory or an industrial estate. Afterwards, The approach is validated by case study. Finally, the sustainable design approach underpinned with life cycle impact assessment (LCIA) and ontology is developed
Strong Correlations and Magnetic Frustration in the High Tc Iron Pnictides
We consider the iron pnictides in terms of a proximity to a Mott insulator.
The superexchange interactions contain competing nearest-neighbor and
next-nearest-neighbor components. In the undoped parent compound, these
frustrated interactions lead to a two-sublattice collinear antiferromagnet
(each sublattice forming a Neel ordering), with a reduced magnitude for the
ordered moment. Electron or hole doping, together with the frustration effect,
suppresses the magnetic ordering and allows a superconducting state. The
exchange interactions favor a d-wave superconducting order parameter; in the
notation appropriate for the Fe square lattice, its orbital symmetry is
. A number of existing and future experiments are discussed in light of
the theoretical considerations.Comment: (v2) 4+ pages, 4 figures, discussions on several points expanded;
references added. To appear in Phys. Rev. Let
Tractable approximate deduction for OWL
Acknowledgements This work has been partially supported by the European project Marrying Ontologies and Software Technologies (EU ICT2008-216691), the European project Knowledge Driven Data Exploitation (EU FP7/IAPP2011-286348), the UK EPSRC project WhatIf (EP/J014354/1). The authors thank Prof. Ian Horrocks and Dr. Giorgos Stoilos for their helpful discussion on role subsumptions. The authors thank Rafael S. Gonçalves et al. for providing their hotspots ontologies. The authors also thank BoC-group for providing their ADOxx Metamodelling ontologies.Peer reviewedPostprin
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