2,427 research outputs found
Accidents at urban mini-roundabouts
No full textThe report gives the findings of a study of accident risk based on a national stratified sample of 200 3-arm and 100 4-arm urban mini-roundabouts on 30mph single carriageway roads (2100 personal injury accidents). Tabulations are given showing frequencies, severities and rates by type of central island and by region. The accidents are also tabulated by accident group, road user involvement and number of casualties per accident. The main objective of the study was to develop relationships between accident frequency and traffic flow, road features, layout, geometry, land use and other variables. The technique of generalised linear modelling was used to develop such relationships for different types of accidents
Marriage record of Goode, John G. and Kennedy, Hattie
No full textMarriage license for John G. Goode and Hattie Kennedy. R.D. Sergio was the officiant
Efficient parallel computing with a compact finite difference scheme
No full textThis paper proposes an efficient parallel computing approach based on a high-order accurate compact finite difference scheme in conjunction with a conventional domain decomposition method and MPI libraries. The proposed parallel computing approach consists of two major features: (a) a newly developed compact finite difference scheme with extended stencils containing halo points around subdomain boundaries, and (b) a predictor–corrector type implementation of a compact filter that effectively suppresses spurious errors from the subdomain boundaries. The current work employs three halo cells for the inter-node communication, based on which the coefficients of the new compact scheme at the subdomain boundaries are optimized to achieve as high level of resolution and accuracy as the interior compact scheme provides. Also, an optimal set of cut-off wavenumbers of the compact filter that minimizes spurious errors is suggested. It is shown that the level of errors from the proposed parallel calculations lies within the same order of magnitude of that from the single-domain serial calculations. The overall accuracy and linear stability of the new parallel compact differencing-filtering system are confirmed by grid convergence tests and eigenvalue analyses. The proposed approach shows a substantial improvement with respect to existing methods available
Solution of the problem of composite charge using R.D.38
No full textIn this paper the author has solved the problem of internal ballistics of composite charge using 'R.D.38' method which is based upon the usual isothermal approximation. A linear law of burning has been assumed
Assessing the sensitivity of turbine cascade flow to inflow disturbances using direct numerical simulation
No full textAuthor index
No full textThe articles have been scanned in colour with a HP Scanjet 5590; 300dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.This is a continuation of the "Author and Subject Index to the Onderstepoort Journal
of Veterinary Science and Animal Industry (1933- l950)" and the "Onderstepoort Journal
of Veterinary Research (1951 - 1968)" which appeared in June 1969 and covers the period
1969 to 1973, i.e. Volumes 36 to 40.
As from 1974 (Volume 41) it is intended to furnish an Author and Subject Index
in Number 4 of each volume covering all four numbers for that particular year
Noise due to unsteady flow past trailing edges
No full textThis paper presents two-dimensional direct numerical simulations (DNS) of noise generated at trailing edges (TE) with zero thickness. The simulations are conducted specifying either no-slip or slip walls in order to investigate viscous effects. In both cases, small amplitude disturbances are introduced close to the inflow boundary that serve as pressure disturbances at the TE. DNS data reveals that the unsteady Kutta condition is not satisfied, irrespective of the wall boundary condition. However, it appears that the validity of the unsteady Kutta condition is not essential for making an accurate prediction of the far field noise. The far field pressure is predicted as a function of the surface pressure difference using a 2-D modification of Amiet's classical theory, and compared with the far field pressure computed directly. Directivity plots provide evidence that the presence of boundary layers and noise generated by an unsteady wake in the no-slip cases lead to smearing of individual lobes, and that the downstream pointing lobes in no-slip wall cases are probably due to nonlinear noise generation in the wake. The simulations are conducted using a high-order accurate numerical method which is free of upwinding, artificial dissipation or any form of explicit filtering, and employs a novel boundary treatment
Investigating past methane cycle perturbations through the lens of novel polyfunctionalised hopanoids
No full textEnhanced aerobic methanotrophy has been inferred in wetland environments during past warm climates, notably the Paleocene-Eocene Thermal Maximum (PETM; ∼56 Ma). This is based on a negative carbon isotope excursion in bacterial-derived hopanes (d13Chop). However, these compounds have multiple source organisms and their d13Chop can also reflect changes in the metabolic pathway used to assimilate carbon. In contrast, bacteriohopanepolyols (BHPs) are polyfunctionalised hopanoids that may be a more diagnostic tracer of methane oxidation, but their preservation potential is unclear. In this study, we aim to: (i) determine the preservation of novel BHPs during the PETM; and (ii) explore the potential of BHPs as a proxy to reconstruct past methane cycle dynamics. Overall, our study presents the most diverse bacteriohopanepolyol profile found thus far in sedimentary deposits beyond 50 million years ago, suggesting excellent preservation. Interestingly, a peak in 35-aminobacteriohopane-30,31,32,33,34-pentol (aminopentol) coincides with the most negative d13Chop value during the PETM. An increase in aminopentol during the PETM was also previously observed, further supporting the utility of aminopentol as a proxy for methane cycling during transient warming events
Characteristic distribution and scale interaction of turbulence in a boundary layer
No full textThis work revisits the concept of turbulent boundary layers from a novel perspective on scale transfer. Turbulence production and dissipation together with the energy budgets are analyzed in the velocity gradient invariant phase space. In combination with filtering, the mechanism of scale coupling is investigated and illustrated for different characteristic flow topologies. The understanding of the scale coupling is important to model turbulence. Turbulence models describe the complex interaction of the scales of motion in a simplified form. The essential task of turbulence modeling is to capture the coupling of the modeled and unmodeled scales as well as the evolution of the modeled scales within the unmodeled flow. This work characterizes the scale coupling by focusing on the interfaces between modeled and unmodeled flow such as production and dissipation. The mechanisms that govern the evolution of the modeled quantities are investigated for their core properties and universal features. Direct numerical simulation (DNS) is carried out to obtain data of a compressible zero pressure-gradient flat plate turbulent boundary layer flow. This flow topology allows to unveil the effect of a wall on the coupling of scales and evolution of turbulence
Learning from One's Mistakes
No full textCreated by R.D. Lee for the Royal Statistics Society, this article describes an exercise, which highlights the effect of sampling without replacement in small populations, and leads to consideration of the relative importance of sample and population size when examining standard error. The author provides a number of exercises, an explanation of statistical errors and the importance of sample size. This is a brief, yet fine resource for those in the field of statistics
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