Relevance of similitude parameters for drag reduction in sport aerodynamics

AbstractIt is possible to improve the aerodynamics of an athlete by influencing the location at which the boundary layer transition occurs on the body. The state of the boundary layer and therefore the drag coefficient depend mainly, in the critical Reynolds number range, on the shape, the aspect ratio and the 3-dimensionality of the body, the fabric properties and the wind turbulence. When planning a wind tunnel experiment, some of these factors are sometimes neglected. In this research, it was observed that each parameter was relevant and had a relatively large impact on the drag coefficient. Wind-tunnel tests on a 1:1 scale mannequin of an elite athlete were conducted in a fully controlled environment. They allowed the proper representation of the body proportions and cross-section dimensions as well as the 3-dimensionality aspect. It was observed that the flow interaction between the limbs dictated which fabric provided the lowest drag for each part of the body for a desired range of wind speed. An inappropriate simulation of the conditions can optimise the drag reduction for an erroneously targeted Reynolds number range. The research provided a quantitative evaluation of the relevance of correctly simulating parameters for drag reduction in sport aerodynamics

Fine-mapping of prostate cancer susceptibility loci in a large meta-analysis identifies candidate causal variants

Prostate cancer is a polygenic disease with a large heritable component. A number of common, low-penetrance prostate cancer risk loci have been identified through GWAS. Here we apply the Bayesian multivariate variable selection algorithm JAM to fine-map 84 prostate cancer susceptibility loci, using summary data from a large European ancestry meta-analysis. We observe evidence for multiple independent signals at 12 regions and 99 risk signals overall. Only 15 original GWAS tag SNPs remain among the catalogue of candidate variants identified; the remainder are replaced by more likely candidates. Biological annotation of our credible set of variants indicates significant enrichment within promoter and enhancer elements, and transcription factor-binding sites, including AR, ERG and FOXA1. In 40 regions at least one variant is colocalised with an eQTL in prostate cancer tissue. The refined set of candidate variants substantially increase the proportion of familial relative risk explained by these known susceptibility regions, which highlights the importance of fine-mapping studies and has implications for clinical risk profiling. © 2018 The Author(s).Prostate cancer is a polygenic disease with a large heritable component. A number of common, low-penetrance prostate cancer risk loci have been identified through GWAS. Here we apply the Bayesian multivariate variable selection algorithm JAM to fine-map 84 prostate cancer susceptibility loci, using summary data from a large European ancestry meta-analysis. We observe evidence for multiple independent signals at 12 regions and 99 risk signals overall. Only 15 original GWAS tag SNPs remain among the catalogue of candidate variants identified; the remainder are replaced by more likely candidates. Biological annotation of our credible set of variants indicates significant enrichment within promoter and enhancer elements, and transcription factor-binding sites, including AR, ERG and FOXA1. In 40 regions at least one variant is colocalised with an eQTL in prostate cancer tissue. The refined set of candidate variants substantially increase the proportion of familial relative risk explained by these known susceptibility regions, which highlights the importance of fine-mapping studies and has implications for clinical risk profiling. © 2018 The Author(s).Peer reviewe

An investigation of low-speed wing buffet

SIGLEAvailable from British Library Document Supply Centre- DSC:D061511 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Modeling helicopter blade sailing: Model validation using experimental data

Blade sailing is an aeroelastic phenomenon that can occur during the engage and disengage phases of shipboard helicopter operation. Over the past several years, a number of simulation tools, including structural, dynamic and aerodynamic models, have been developed at Carleton University and the National Research Council of Canada towards a comprehensive study of the blade sailing phenomenon. In order to validate the applicability of the tools in the complexity of the blade sailing environment, an experimental test programme has been developed. This programme involves recording the time history of blade deflection data for a Froude scaled two-bladed rotor during representative rotor engage and disengage. In this paper, a description of the simulation tools that have been developed is briefly given. The details of the experiment, including design, execution

Investigation of the active-twist rotor response of various rotor system configurations during shipboard engagement and disengagement operations

The unique hazard of excessive blade flapping during the rotor engage and disengage phase of shipboard helicopter operation and previous control strategies investigated for mitigating this problem are briefly presented. A hybrid control strategy is proposed that combines a previously deemed unfeasible passive approach known as the collective pitch scheduling and an active integral twist due to embedded Active Fibre Composites (AFCs). This stipulates the examination of the active twist authority of the active rotor system in this unique phase of helicopter operation and associated environment. The preliminary results of such a study are presented for a generic active blade based on the 1/6 th Mach-scaled Integral Active Twist Rotor (IATR) and an empirical steady airwake model over a generic ship deck. The results demonstrate the dependence of the active twist authority on the blade tip geometry and the aerodynamics envir

High-resolution imaging of biotite using focal series exit wavefunction restoration and the graphene mechanical exfoliation method

We have applied mechanical exfoliation for the preparation of ultra-thin samples of the phyllosilicate mineral biotite. We demonstrate that the 'scotch tape' approach, which was made famous as an early method for production of single-atom-thick graphene, can be used for production of sheet-silicate specimens that are sufficiently thin to allow high-resolution transmission electron microscope (HRTEM) imaging to be achieved successfully while also being free from the specimen preparation artefacts that are often caused by ion-beam milling techniques. Exfoliation of the biotite parallel to the (001) planes has produced layers as thin as two structural TOT units thick (~2 nm). The minimal specimen thickness enabled not only HRTEM imaging but also the application of subsequent exit wavefunction restoration to reveal the pristine biotite lattice. Exit wavefunction restoration recovers the full complex electron wave from a focal series of HRTEM images, removing the effects of coherent lens aberrations. This combination of methods therefore produces images in which the observed features are readily interpreted to obtain atomic resolution structural information. © 2015 Mineralogical Society 2015