Turbulent dispersion in a stable layer with a quadratic exchange coefficient     

R. E. Robson 《Boundary-Layer Meteorology》1987,39(3):207-218

Dispersion from a line source into a stable boundary layer of thickness l is analysed through solution of the diffusion equation assuming an exchange coefficient K(z) (1 – z/l) ² and wind profiles u(z) z ⁿ, with n = 0,1. Estimates of ground-level concentrations are made by developing analytic formulae where this is possible. A general method of solution using Laplace transformation and Green's function techniques is developed as an alternative to the eigenfunction expansion method discussed previously (Robson, 1983).  相似文献   

Contesting the political     

Dave Featherstone 《Area》2007,39(1):131-132

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International Year of Astronomy 2009     

Ian Robson 《Astronomy& Geophysics》2007,48(4):4.30-4.30

IYA2009 will be a great opportunity for all of us working in astronomy (and space) to make an impact; certainly locally and nationally and, we hope, globally. So what is going on and how can you participate? Ian Robson has the answers.  相似文献   

A Framework and Software Tool to Support Collaborative Landscape Analysis: Fitting Square Pegs into Square Holes   总被引：2，自引：0，他引：2  

Andrew Fall  Dave Daust  & Don G. Morgan 《Transactions in GIS》2001,5(1):67-86

For landscape models to be applied successfully in management situations, models must address appropriate questions, include relevant processes and interactions, be perceived as credible and involve people affected by decisions. We propose a framework for collaborative model building that can address these issues, and has its roots in adaptive management, computer‐supported collaborative work and landscape ecology. Models built through this framework integrate a variety of information sources, address relevant questions, and are customized for the particular landscape and policy environment under study. Participants are involved in the process from the start, and because their input is incorporated, they feel ownership of the resulting models, increasing the chance of model acceptance and application. There are two requirements for success: a tool that supports rapid model prototyping and modification, that makes a clear link between a conceptual and implemented model, and that has the ability to implement a wide range of model types; and a core team with skills in communication, research and analysis, and knowledge of ecology and forestry in addition to modelling. SELES (Spatially Explicit Landscape Event Simulator) is a tool for building and running models of landscape dynamics. It combines discrete event simulation with a spatial database and a relatively simple modelling language to allow rapid development of landscape simulations, and provides a high‐level means of specifying complex model behaviours ranging from management actions to natural disturbance and succession. We have applied our framework in several forest modelling projects in British Columbia, Canada. We have found that this framework increases the interest by local experts and decision‐makers to participate actively in the model building process. The workshop process and resulting models have efficiently provided insight into the dynamics of large landscapes over long time frames. The use of SELES has facilitated this process by providing a flexible, transparent environment in which models can be rapidly implemented and refined. As a result, model findings may be more readily incorporated into decision‐support systems designed to assist resource managers in making informed decisions.  相似文献   

The frequency response of the horizontal magnetic field for a conductive channel     

Dave Hebert 《Geophysical Journal International》1983,73(2):577-580

Summary. Babour & Mosnier's results showing no frequency dependence between the anomalous horizontal magnetic field above a conductor and the difference between the horizontal magnetic fields above and below the conductor over a wide range of frequencies led them to conclude that this effect is due to current channelling. A two-dimensional numerical model of a conductive channel, with a uniform horizontal source field, shows the same effect over a wide range of frequencies. Thus local induction can show the same effect.  相似文献   

The effect of stress on faulting and minor intrusions in the vicinity of a magma body     

G. R. Robson  K. G. Barr 《Bulletin of Volcanology》1964,27(1):315-330

The stress field in the vicinity of a body of fluid of simple geometry contained within a non-homogeneously stressed solid has been calculated and the result applied to the case of a magma body within a region of the crust subject to triaxial stresses. The types of faulting and minor intrusion which result are described. The theory indicates that the regional stresses in the crust together with the magma pressure control the type of faulting, the form of the minor intrusions and the occurrence of eruptions from the magma body. The stress conditions favouring caldera formation, the intrusion of radial dykes, dyke swarms and cone sheets are described.  相似文献   

REPLY TO the preceding discussion by S. N. Davis of "Hydrogeology Is More Than a Classical Science," by D. Stephenson, May-June 1974 issue, pp. 148-151     

Dave Stephenson 《Ground water》1974,12(5):319-319

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Assessing damaged road verges as a suspended sediment source in the Hampshire Avon catchment,southern United Kingdom     

A. L. Collins  D. E. Walling  R. W. Stroud  M. Robson  L. M. Peet 《水文研究》2010,24(9):1106-1122

Diffuse sediment pollution impairs water quality, exerts a key control on the transfer and fate of nutrients and contaminants and causes deleterious impacts on freshwater ecology. A variety of catchment sediment sources can contribute to such problems. Sediment control strategies and effective targeting of mitigation options therefore require robust quantitative information on the key sources of the sediment problem at catchment scale. Recent observations by Catchment Sensitive Farming Officers (CSFO's) in England have highlighted road verges damaged and eroded by passing vehicles, particularly large farm machinery, and livestock herd movement as visually important potential sources of local sediment problems. A study was therefore undertaken to assess the relative importance of damaged road verges as a suspended sediment source in three sub‐catchments of the Hampshire Avon drainage basin, southern UK. Road verge sediment contributions were apportioned in conjunction with those from agricultural topsoils and channel banks/subsurface sources. Time‐integrating isokinetic samplers were deployed to sample suspended sediment fluxes at the outlets of two control sub‐catchments drained by the Rivers Chitterne and Till selected to characterize areas with a low road network density and limited visual evidence of verge damage, as well as the River Sem sub‐catchment used to represent areas where road verge damage is more prevalent. The findings of a sediment source fingerprinting investigation based on a combination of intermittent sampling campaigns spanning the period 22/5/02–27/4/08 suggested that the respective overall mean relative sediment contributions from damaged road verges were 5 ± 3%, 4 ± 2% and 20 ± 2%. Relative inputs from damaged road verges for any specific sampling period in the River Sem sub‐catchment were as high as 33 ± 2%. Reconstruction of historical sources in the same sub‐catchment, based on the geochemical record stored in a floodplain depth profile, suggested that the significance of damaged road verges as a sediment source has increased over the past 15–20 years. The findings provide important information on damaged road verges as a primary source of suspended sediment and imply that catchment sediment control strategies and mitigation plans should consider such verges in addition to those agricultural and channel sources traditionally taken into account when attempting to reduce sediment pressures on aquatic resources. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

The stellar mass content of distant galaxy groups     

Michael L. Balogh  Dave Wilman  Robert D. E. Henderson  Richard G. Bower  David Gilbank  Richard Whitaker  Simon L. Morris  George Hau  J. S. Mulchaey  A. Oemler  Jr    R. G. Carlberg 《Monthly notices of the Royal Astronomical Society》2007,374(3):1169-1180

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Analysing uncertainties in climate change impact assessment across sectors and scenarios     

Calum Brown  Evan Brown  Dave Murray-Rust  George Cojocaru  Cristina Savin  Mark Rounsevell 《Climatic change》2015,128(3-4):293-306

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