Institution
Central Electricity Generating Board
Government•London, England, United Kingdom•
About: Central Electricity Generating Board is a government organization based out in London, England, United Kingdom. It is known for research contribution in the topics: Creep & Grain boundary. The organization has 2018 authors who have published 1858 publications receiving 41606 citations.
Topics: Creep, Grain boundary, Oxide, Fracture mechanics, Corrosion
Papers published on a yearly basis
Papers
More filters
••
TL;DR: It is shown that the 1.5-eV optical gap of a-C:H is unusually small and requires that both its valence and conduction band consist of \ensuremath{\pi} states on ${\mathrm{sp}}^{2}$ sites and that these sites must also be significantly clustered, such as in graphitic clusters containing four or more rings.
Abstract: The electronic structure of amorphous carbon and hydrogenated amorphous carbon (a-C:H) has been investigated through calculations on a number of model structures containing different configurations of ${\mathrm{sp}}^{2}$ and ${\mathrm{sp}}^{3}$ sites. We find that the most stable arrangement of ${\mathrm{sp}}^{2}$ sites is in compact clusters of fused sixfold rings, i.e., graphitic layers. The width of the optical gap is found to vary inversely with the ${\mathrm{sp}}^{2}$ cluster size, and the \ensuremath{\sim}0.5-eV optical gap of evaporated amorphous carbon is found to be consistent with a model of disordered graphitic layers of about 15 A\r{} in diameter, bounded by ${\mathrm{sp}}^{3}$ sites. It is argued that a-C forms such finite clusters in order to relieve strain. It is then shown that the 1.5--2.5-eV optical gap of a-C:H is unusually small and requires that both its valence and conduction band consist of \ensuremath{\pi} states on ${\mathrm{sp}}^{2}$ sites and that these sites must also be significantly clustered, such as in graphitic clusters containing four or more rings. In other words, the optical gap of both a-C and a-C:H depends on their degree of medium-range order, rather than just on their short-range order as is the case in most amorphous semiconductors. We have also studied the nature of states away from the gap in order to interpret the photoemission data and the carbon 1s core-level absorption spectra. The nature of defects and midgap states is discussed, and it is predicted that the defect density decreases with increasing band gap. Finally it is argued that the doping of a-C:H by group-III and -V elements proceeds via a substitution mechanism, as in a-Si:H, in spite of the coordination disorder present in a-C:H. Doping is also expected to be accompanied by an increase in gap states, as in a-Si:H.
1,227 citations
••
TL;DR: A number of methods are now available for assessing the integrity of structures containing flaws in all loading regimes as discussed by the authors, and one of these methods is used to define a route for establishing the structural integrity of a structure containing defects.
809 citations
••
642 citations
••
TL;DR: In this article, an experimental investigation of the flow around surface mounted cubes in both uniform, irrotational and sheared, turbulent flows is described, and comparisons with the somewhat sparse measurements of previous workers are made and the relevance of recent theoretical attempts to describe the flow, as opposed to numerical calculation techniques to predict it, is briefly discussed.
Abstract: An experimental investigation of the flow around surface-mounted cubes in both uniform, irrotational and sheared, turbulent flows is described. The shear flow was a simulated atmospheric boundary layer with a height ten times the body dimension. Measurements of body surface pressures and mean and fluctuating velocities within the wake are presented. In the latter case a pulsed-wire anemometer was used extensively since the turbulent intensities were much too high for effective use of more standard instrumentation. The clear effects of upstream turbulence and shear on the wake flow are described, comparisons with the somewhat sparse measurements of previous workers are made and the relevance of recent theoretical attempts to describe the flow, as opposed to numerical calculation techniques to predict it, is briefly discussed.
639 citations
••
TL;DR: In this article, a numerical model is described which can be used to calculate the wake flowfield of wind turbines and the effect of meteorological conditions on wake decay is examined in detail.
603 citations
Authors
Showing all 2019 results
Name | H-index | Papers | Citations |
---|---|---|---|
John Robertson | 123 | 890 | 81089 |
Donald A. Norman | 93 | 292 | 71226 |
Peter Tavner | 52 | 143 | 12519 |
Peter Clark | 45 | 178 | 6555 |
Ian P. Castro | 43 | 146 | 7276 |
Tristram Chivers | 42 | 546 | 8594 |
M. J. Graham | 41 | 176 | 4792 |
Peter Henderson | 39 | 121 | 6096 |
Trevor C. Lindley | 37 | 81 | 4183 |
John Shepherd | 35 | 94 | 5567 |
Colin P. Please | 32 | 181 | 3501 |
Hugh Evans | 32 | 125 | 4100 |
Geoffrey C. Allen | 31 | 146 | 3328 |
Richard Skeffington | 28 | 65 | 2472 |
George V. Buxton | 28 | 99 | 3358 |