Experimental techniques for ductile damage characterisation

Ductile damage in metallic materials is caused by the nucleation, growth and coalesce of voids and micro-cracks in the metal matrix when it is subjected to plastic strain. A considerable number of models have been proposed to represent ductile failure focusing on the ultimate failure conditions; however, only some of them study in detail the whole damage accumulation process. The aim of this work is to review experimental techniques developed by various authors to measure the accumulation of ductile damage under tensile loads. The measurement methods reviewed include: stiffness degradation, indentation, microstructure analysis, ultrasonic waves propagation, X-ray tomography and electrical potential drop. Stiffness degradation and indentation techniques have been tested on stainless steel 304L hourglass-shaped samples. A special interest is placed in the Continuum Damage Mechanics approach (CDM) as its equations incorporate macroscopic parameters that can represent directly the damage accumulation measured in the experiments. The other main objective lies in identifying the strengths and weaknesses of each technique for the assessment of materials subjected to different strain-rate and temperature conditions

An experimental methodology to characterise post-necking behaviour and quantify ductile damage accumulation in isotropic materials

The development of ductile damage, that occurs beyond the point of necking in a tensile test, can be difficult to quantify. An experimental methodology has been developed to accurately characterise the post-necking deformation response of a material through continuous monitoring of the specimens shape up until rupture. By studying the evolution of the neck geometry, the correct values of the local stress and strain have been determined in samples of grade 304L stainless steel and C110 copper. Notched bar specimens of various notch acuities were examined enabling the effects of stress triaxiality on ductile fracture to be determined. The methodology developed has provided a robust framework for macroscopic measurements of ductile damage during the necking process. To characterise the material degradation process, the elastic modulus reduction method was employed on hourglass-shaped specimens of the same materials. Stiffness degradation was measured using a small gauge extensometer during uninterrupted tensile tests with partial elastic unloadings. A metallographic study was conducted on progressively damaged specimens in order to validate the macroscopic damage measurements. A new non-linear ductile damage accumulation law has been developed and calibrated, which provides an advanced representation of the experimental results, and a significant improvement compared to linear accumulation models frequently employed. This realistic modelling approach considers the degradation of the material when it has undergone severe plastic deformation, and provides a more accurate representation of the near failure behaviour by considering the effects of stress triaxiality. The methodology provides accurate data for damage model development and calibration, to improve the predictions of remnant life from ductile damage in engineering components

no Routing Needed Between Capsules

Copyright © 2021 The Authors. Most capsule network designs rely on traditional matrix multiplication between capsule layers and computationally expensive routing mechanisms to deal with the capsule dimensional entanglement that the matrix multiplication introduces. By using Homogeneous Vector Capsules (HVCs), which use element-wise multiplication rather than matrix multiplication, the dimensions of the capsules remain unentangled. In this work, we study HVCs as applied to the highly structured MNIST dataset in order to produce a direct comparison to the capsule research direction of Geoffrey Hinton, et al. In our study, we show that a simple convolutional neural network using HVCs performs as well as the prior best performing capsule network on MNIST using 5.5× fewer parameters, 4× fewer training epochs, no reconstruction sub-network, and requiring no routing mechanism. The addition of multiple classification branches to the network establishes a new state of the art for the MNIST dataset with an accuracy of 99.87% for an ensemble of these models, as well as establishing a new state of the art for a single model (99.83% accurate)

The ‘Hothaps’ programme for assessing climate change impacts on occupational health and productivity: an invitation to carry out field studies

The ‘high occupational temperature health and productivity suppression’ programme (Hothaps) is a multi-centre health research and prevention programme aimed at quantifying the extent to which working people are affected by, or adapt to, heat exposure while working, and how global heating during climate change may increase such effects. The programme will produce essential new evidence for local, national and global assessment of negative impacts of climate change that have largely been overlooked. It will also identify and evaluate preventive interventions in different social and economic settings

Probation staff experiences of managing suicidal and self-harming service users

The current study sought to explore the impact of suicidal behaviours on probation staff, in relation to their experiences of working with Probation service users who have carried out suicide, attempted suicide or self-harm. Thirteen in-depth interviews were carried out with probation staff who had direct contact with Probation service users in one Probation area, and had varying degrees of experience of managing suicidal or self-injurious service users. These were analysed using Thematic Analysis and five themes were identified. Findings indicate that staff felt that suicide and self-harm by service users are serious issues which need to be recognised and dealt with in an effective yet compassionate manner. However not attending the Suicide Prevention Training or lack of experience was perceived as restricting their ability to know how to deal with these individuals, and offer support. Furthermore, staff were emotionally affected by these incidents and it is recommend that they should continue to be provided with access to appropriate support services after an incident

Comparative Genome Analysis Reveals Divergent Genome Size Evolution in a Carnivorous Plant Genus

The C-value paradox remains incompletely resolved after >40 yr and is exemplified by 2,350-fold variation in genome sizes of flowering plants. The carnivorous Lentibulariaceae genus , displaying a 25-fold range of genome sizes, is a promising subject to study mechanisms and consequences of evolutionary genome size variation. Applying genomic, phylogenetic, and cytogenetic approaches, we uncovered bidirectional genome size evolution within the genus . The Steyerm. genome (86 Mbp) has probably shrunk by retroelement silencing and deletion-biased double-strand break (DSB) repair, from an ancestral size of 400 to 800 Mbp to become one of the smallest among flowering plants. The Stapf genome has expanded by whole-genome duplication (WGD) and retrotransposition to 1550 Mbp. became allotetraploid after the split from the clade ∼29 Ma. A. St.-Hil. (179 Mbp), a close relative of , proved to be a recent (auto)tetraploid. Our analyses suggest a common ancestor of the genus a with an intermediate 1C value (400–800 Mbp) and subsequent rapid genome size evolution in opposite directions. Many abundant repeats of the larger genome are absent in the smaller, casting doubt on their functionality for the organism, while recurrent WGD seems to safeguard against the loss of essential elements in the face of genome shrinkage. We cannot identify any consistent differences in habitat or life strategy that correlate with genome size changes, raising the possibility that these changes may be selectively neutral

Chloroquine and inhibition of Toll-like receptor 9 protect from sepsis-induced acute kidney injury

Mortality from sepsis has remained high despite recent advances in supportive and targeted therapies. Toll-like receptors (TLRs) sense bacterial products and stimulate pathogenic innate immune responses. Mice deficient in the common adapter protein MyD88, downstream from most TLRs, have reduced mortality and acute kidney injury (AKI) from polymicrobial sepsis. However, the identity of the TLR(s) responsible for the host response to polymicrobial sepsis is unknown. Here, we show that chloroquine, an inhibitor of endocytic TLRs (TLR3, 7, 8, 9), improves sepsis-induced mortality and acute kidney injury in a clinically relevant polymicrobial sepsis mouse model, even when administered 6h after the septic insult. Chloroquine administration attenuated the decline in renal function, splenic apoptosis, serum markers of damage to other organs, and prototypical serum pro- and anti-inflammatory cytokines TNF-alpha and IL-10. An oligodeoxynucleotide inhibitor (H154) of TLR9 and TLR9-deficient mice mirror the actions of chloroquine in all functional parameters that we tested. In addition, chloroquine decreased TLR9 protein abundance in spleen, further suggesting that TLR9 signaling may be a major target for the protective actions of chloroquine. Our findings indicate that chloroquine improves survival by inhibiting multiple pathways leading to polymicrobial sepsis, and that chloroquine and TLR9 inhibitors represent viable broad-spectrum and targeted therapeutic strategies, respectively, that are promising candidates for further clinical development

DN interaction from meson exchange

A model of the DN interaction is presented which is developed in close analogy to the meson-exchange KbarN potential of the Juelich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (rho, omega) exchange and higher-order box diagrams involving D*N, D\Delta, and D*\Delta intermediate states. The coupling of DN to the pi-Lambda_c and pi-Sigma_c channels is taken into account. The interaction model generates the Lambda_c(2595) resonance dynamically as a DN quasi-bound state. Results for DN total and differential cross sections are presented and compared with predictions of an interaction model that is based on the leading-order Weinberg-Tomozawa term. Some features of the Lambda_c(2595) resonance are discussed and the role of the near-by pi-Sigma_c threshold is emphasized. Selected predictions of the orginal KbarN model are reported too. Specifically, it is pointed out that the model generates two poles in the partial wave corresponding to the Lambda(1405) resonance.Comment: 14 pages, 8 figure

Selecting Grassland Species for Saline Environments

In Australia, around 5.7 million hectares of agricultural land are currently affected by dryland salinity or at risk from shallow water tables and this figure is expected to increase over the next 50 years (LWRA, 2001). Most improved grassland species cannot tolerate the combined effects of salt and waterlogging and, therefore, the productivity of sown grasslands in salt-affected areas is low. However, there is potential to overcome the lack of suitably adapted fodder species by introducing new, salt and waterlogging-tolerant species and by diversifying the gene pool of proven species. Potential species include exotic, naturalised and native Australian grass, legumes, herb and shrub species that are halophytes and non-halophytes. A collaborative national project in southern Australia commenced in 2004 with the objective of evaluating a range of forage species for saline environments