Three-dimensional nonlinear micro/meso-mechanical response of the fibre-reinforced polymer composites

A three-dimensional multi-scale computational homogenisation framework is developed for the prediction of nonlinear micro/meso-mechanical response of the fibre-reinforced polymer (FRP) composites. Two dominant damage mechanisms, i.e. matrix elasto-plastic response and fibre–matrix decohesion are considered and modelled using a non-associative pressure dependent paraboloidal yield criterion and cohesive interface elements respectively. A linear-elastic transversely isotropic material model is used to model yarns/fibres within the representative volume element (RVE). A unified approach is used to impose the RVE boundary conditions, which allows convenient switching between linear displacement, uniform traction and periodic boundary conditions. The computational model is implemented within the framework of the hierarchic finite element, which permits the use of arbitrary orders of approximation. Furthermore, the computational framework is designed to take advantage of distributed memory high-performance computing. The accuracy and performance of the computational framework are demonstrated with a variety of numerical examples, including unidirectional FRP composite, a composite comprising a multi-fibre and multi-layer RVE, with randomly generated fibres, and a single layered plain weave textile composite. Results are validated against the reference experimental/numerical results from the literature. The computational framework is also used to study the effect of matrix and fibre–matrix interfaces properties on the homogenised stress–strain responses

The tensor structure on the representation category of the Wp\mathcal{W}_p triplet algebra

We study the braided monoidal structure that the fusion product induces on the abelian category $\mathcal{W}_p$-mod, the category of representations of the triplet $W$-algebra $\mathcal{W}_p$. The $\mathcal{W}_p$-algebras are a family of vertex operator algebras that form the simplest known examples of symmetry algebras of logarithmic conformal field theories. We formalise the methods for computing fusion products, developed by Nahm, Gaberdiel and Kausch, that are widely used in the physics literature and illustrate a systematic approach to calculating fusion products in non-semi-simple representation categories. We apply these methods to the braided monoidal structure of $\mathcal{W}_p$-mod, previously constructed by Huang, Lepowsky and Zhang, to prove that this braided monoidal structure is rigid. The rigidity of $\mathcal{W}_p$-mod allows us to prove explicit formulae for the fusion product on the set of all simple and all projective $\mathcal{W}_p$-modules, which were first conjectured by Fuchs, Hwang, Semikhatov and Tipunin; and Gaberdiel and Runkel.Comment: 58 pages; edit: added references and revisions according to referee reports. Version to appear on J. Phys.

Biogeographical patterns in soil bacterial communities across the Arctic region

The considerable microbial diversity of soils and key role in biogeochemical cycling have led to growing interest in their global distribution and the impact that environmental change might have at the regional level. In the broadest study of Arctic soil bacterial communities to date, we used high-throughput DNA sequencing to investigate the bacterial diversity from 200 independent Arctic soil samples from 43 sites. We quantified the impact of spatial and environmental factors on bacterial community structure using variation partitioning analysis, illustrating a nonrandom distribution across the region. pH was confirmed as the key environmental driver structuring Arctic soil bacterial communities, while total organic carbon (TOC), moisture and conductivity were shown to have little effect. Specialist taxa were more abundant in acidic and alkaline soils while generalist taxa were more abundant in acidoneutral soils. Of the 48 147 bacterial taxa, a core microbiome composed of only 13 taxa that were ubiquitously distributed and present within 95% of samples was identified, illustrating the high potential for endemism in the region. Overall, our results demonstrate the importance of spatial and edaphic factors on the structure of Arctic soil bacterial communities

Multiscale modelling of the textile composite materials

This paper presents an initial computational multiscale modelling of the fibre-reinforced composite materials. This study will constitute an initial building block of the computational framework, developed for the DURCOMP (providing confidence in durable composites) EPSRC project, the ultimate goal of which is the use of advance composites in the construction industry, while concentrating on its major limiting factor ”durability”. The use of multiscale modelling gives directly the macroscopic constitutive behaviour of the structures based on its microscopically heterogeneous representative volume element (RVE). The RVE is analysed using the University of Glasgow in-house parallel computational tool, MoFEM (Mesh Oriented Finite Element Method), which is a C++ based finite-element code. A single layered plain weave is used to model the textile geometry. The geometry of the RVE mainly consists of two parts, the fibre bundles and matrix, and is modelled with CUBIT, which is a software package for the creation of parameterised geometries and meshes. Elliptical cross sections and cubic splines are used respectively to model the cross sections and paths of the fibre bundles, which are the main components of the yarn geometry. In this analysis, transversely isotropic material is introduced for the fibre bundles, and elastic material is used for the matrix part. The directions of the fibre bundles are calculated using a potential flow analysis across the fibre bundles, which are then used to define the principal direction for the transversely isotropic material. The macroscopic strain field is applied using linear displacement boundary conditions. Furthermore, appropriate interface conditions are used between the fibre bundles and the matrix

Difference in general practice telehealth utilisation associated with birth country during COVID-19 from two Australian states

Objective: Telehealth has been an integral part of ensuring continued general practice access during the COVID-19 pandemic. Whether telehealth was similarly adopted across different ethnic, cultural, and linguistic groups in Australia is unknown. In this study, we assessed how telehealth utilisation differed by birth country. Methods: In this retrospective observational study, electronic health record data from 799 general practices across Victoria and New South Wales, Australia between March 2020 to November 2021 were extracted (12,403,592 encounters from 1,307,192 patients). Multivariate generalised estimating equation models were used to assess the likelihood of a telehealth consultation (against face-to-face consultation) by birth country (relative to Australia or New Zealand born patients), education index, and native language (English versus others). Results: Patients born in Southeastern Asia (aOR: 0.54; 95% CI: 0.52–0.55), Eastern Asia (aOR: 0.63; 95% CI: 0.60–0.66), and India (aOR: 0.64; 95% CI: 0.63–0.66) had a lower likelihood of having a telehealth consultation compared to those born in Australia or New Zealand. Northern America, British Isles, and most European countries did not present with a statistically significant difference. Additionally, higher education levels (aOR: 1.34; 95% CI: 1.26–1.42) was associated with an increase in the likelihood of a telehealth consultation, while being from a non-English-speaking country was associated with a reduced likelihood (aOR: 0.83; 95% CI: 0.81–0.84). Conclusions: This study provides evidence showing differences in telehealth use associated with birth country. Strategies to ensure continued healthcare access for patients, whose native language is not English, such as providing interpreter services for telehealth consultations, would be beneficial. Perspectives: Understanding cultural and linguistic differences may reduce health disparities in telehealth access in Australia and could present an opportunity to promote healthcare access in diverse communities

Predictive Association of Pre-Operative Defect Areas in the Outer Retinal Layers With Visual Acuity in Macular Hole Surgery

Purpose: The purpose of this study was to develop methods to model the external limiting membrane (ELM) and ellipsoid zone (EZ) within the elevated cuff surrounding a macular hole (MH) to determine if the predicted size of the defect in these layers after virtual flattening was associated with the actual postoperative defect and best corrected visual acuity (BCVA). Methods: Patients were included who had undergone successful MH surgery. The defects in the ELM and EZ after virtual flattening were modeled using in-house software. Main outcomes were postoperative defects in ELM and EZ at 2 months and BCVA at 12 months. Results: Fifty-eight patients were included. BCVA improved from 0.87 (0.31) logMAR pre-operatively to 0.26 (0.21) at 12 months (P < 0.001). For both the ELM and EZ, the predicted virtually flattened pre-operative defects were associated with the actual postoperative defects at 2 months (R-2 = 0.33, P < 0.01 and R-2 = 0.50, P < 0.01, respectively). There was a significant association of BCVA at 12 months (adjusted R-2 = 0.85) with the pre-operative modeled area of the defect in the ELM (P < 0.01) and to a lesser extent with the defect in the EZ (P < 0.01) and base of the MH (P < 0.01). Conclusions: Virtually flattening of the pre-operative defect in the ELM provides important predictive information of visual acuity. Incorporation of tools into commercially available optical coherence tomography (OCT) devices to facilitate such measurements would provide the clinician with important prognostic information. Translational Relevance: We have developed methodology that can potentially be used to predict the postoperative state of the outer retinal layers and the associated visual outcome in patients undergoing surgery for MH

Enhancement of πA→ππA\pi A \to \pi\pi A Threshold Cross Sections by In-Medium ππ\pi\pi Final State Interactions

We address the problem of pion production in low energy $\pi$-nucleus collisions. For the production mechanism we assume a simple model consisting of a coherent sum of single pion exchange and the excitation---followed by the decay into two pions and a nucleon---of the $N^*(1440)$ resonance. The production amplitude is modified by the final state interaction between the pions calculated using the chirally improved J\"ulich meson exchange model including the polarization of the nuclear medium by the pions. The model reproduces well the experimentally observed $\pi A \to \pi\pi A$ cross sections, especially the enhancement with increasing $A$ of the $\pi^+\pi^-$ mass distribution in the threshold region.Comment: 5 pages RevTeX, 3-eps figure

Numerical simulation of “sand-like” polymer flow during rotational moulding using smoothed particle hydrodynamics method

Rotational moulding is a versatile polymer shaping process used to create enclosed parts from powdered precursors using heat and multi-axis rotation. Controlling the heating process and mould motion is critical to producing high-quality parts, and failures due to incorrect mould coverage or variable wall thickness are common. To date, limited simulation tools exist to predict the motion of the powder within the mould, and operators rely on unreliable prior experience to avoid defects. This paper presents an SPH simulation framework to predict particle flow patterns and powder contact time within a rotating mould. The powder-to-wall contact time was derived from the transient rigid body force (RBF) of different sensors on the mould. The method was compared with the results of DEM simulation and validated by the particle flow pattern of two experimental results. Results showed that the SPH method was capable of simulating particle flow macroscopic properties. The great computing efficiency of SPH compared to DEM simulation was also demonstrated