19,142 research outputs found
A pilot study to assess soil spectroscopic methods for mapping key topsoil properties in the Blackwater sub-catchments (Wensum DTC)
This report describes findings from sampling and analyses of soils across the Blackwater drain catchments, part of the Wensum demonstration test catchment (DTC) project funded by Defra. Recent studies have shown how spectroscopic techniques can be used to estimate soil properties and airborne spectroscopy could be an effective means to aid continuous mapping of soil properties across the landscape. Before an airborne survey is undertaken it is important to assess whether the relationships between infra red (IR) spectra and soil properties are sufficiently strong for the cost of the airborne survey to be justified. A secondary objective was to determine the concentrations of soil organic carbon (SOC) in soils across the cultivated parts of the catchment to determine whether there is any evidence that low SOC concentrations might indicate that the topsoil may exhibit poor structural stability contributing to enhanced sediment in stream and drainage channels
Planck Oscillators in the Background Dark Energy
We consider a model for an underpinning of the universe: there are
oscillators at the Planck scale in the background dark energy. Starting from a
coherent array of such oscillators it is possible to get a description from
elementary particles to Black Holes including the usual Hawking-Beckenstein
theory. There is also a description of Gravitation in the above model which
points to a unified description with electromagnetism.Comment: 18 pages latex; talk at the Max Born Symposium 2009, Wrocla
Implementation of the Delta/Start Model.
This working paper outlines the steps undertaken to develop a dynamic land use transport model. The model is based around an existing transport modelling suite, called START, which has been applied to many urban areas in the UK and abroad. However, its integration with an explicit land use model (called DELTA) was new, and this paper describes the first implementation of the combined dynamic land use transport model for the study area of Fife and Lothian region. The model was used in a PhD thesis and an EPSRC ‘Sustainable Cities’ research project at the Institute for Transport Studies. The paper discusses the processes involved in the full implementation of this model, involving both software development, modification to existing software, and implementation. However, it focuses in particular upon the data requirements and calibration of the various submodels in DELTA. In general the model dataset has been generated using existing study area data from past START applications, plus data from the 1991 Census of population and employment. Not all the disaggregations of data required by the model were available from published, or on-line, sources, and so several disaggregations were undertaken. A feature of the model is that the calibration is undertaken for each submodel individually. In general, the model made use of past research into the relationships that it represents, combined with the judgement of the model developers where no other data was available. The implementation of the location model is discussed in detail, including the use of environmental variables in location choice. This fulfils the main aim of this paper; to provide the technical background for the research projects that make use of this model implementation
On certain classes of solutions of the Weierstrass-Enneper system inducing constant mean curvature surfaces
Analysis of the generalized Weierstrass-Enneper system includes the
estimation of the degree of indeterminancy of the general analytic solution and
the discussion of the boundary value problem. Several different procedures for
constructing certain classes of solutions to this system, including potential,
harmonic and separable types of solutions, are proposed. A technique for
reduction of the Weierstrass-Enneper system to decoupled linear equations, by
subjecting it to certain differential constraints, is presented as well. New
elementary and doubly periodic solutions are found, among them kinks, bumps and
multi-soliton solutions
Links between different analytic descriptions of constant mean curvature surfaces
Transformations between different analytic descriptions of constant mean
curvature (CMC) surfaces are established. In particular, it is demonstrated
that the system descriptive of CMC surfaces within the
framework of the generalized Weierstrass representation, decouples into a
direct sum of the elliptic Sh-Gordon and Laplace equations. Connections of this
system with the sigma model equations are established. It is pointed out, that
the instanton solutions correspond to different Weierstrass parametrizations of
the standard sphere
Microscopic and chemical studies of metal particulates in tree bark and attic dust : evidence for historical atmospheric smelter emissions, Humberside, UK.
Tree barks and attic dusts were examined as historical archives of smelter emissions, with the aim of elucidating the pathways of pollution associated with a plume of Sn and Pb contamination in top soils, found close to the former Capper Pass smelter, Humberside, UK. Samples were collected from three villages within the area of the contamination plume. Scanning Electron Microscopy (SEM) and bulk chemical analyses were used to assess particle type, number and deposition patterns. SEM analysis of dusts and bark revealed that Sn and Pb particles were present in samples from all three villages along with copper, zinc and iron particles. These were almost entirely <10 m in diameter and occurred mostly as oxides, frequently forming clusters of sub-micron crystals. Samples further from the smelter contained considerably fewer particles. We present images of smelter derived Sn particles. Chemical assays of the barks and attic dusts demonstrated that concentrations of Sn, Pb, Cu, As, Sb and Cd diminished with increasing distance from the source. Strong positive correlations were found between Sn and Pb, As, Sb and Cd in the attic dusts. Enrichment Factors (EF) were calculated for these trace elements based on topsoil element concentrations obtained from the soil survey of the study area. Decreases in these trace element concentrations and EF values with distance away from the smelter are consistent with trends found in the soil survey for Sn and Pb and are typical of deposition patterns around smelter stacks. The study demonstrates that tree bark and attic dusts can be effective archives of metal particulates deposited from large static emission sources
A simplified model to predict diurnal water temperature dynamics in a shallow tropical water pool
Water temperature is a critical regulator in the growth and development of malaria mosquito immatures, as they are poikilothermic. Measuring or estimating the diurnal temperature ranges to which these immatures are exposed is of the utmost importance, as these immatures will develop into adults that can transmit malaria. Recent attempts to predict the daily water temperature dynamics in mosquito breeding sites in Kenya have been successful. However, the developed model may be too complex, as the sophisticated equipment that was used for detailed meteorological observations is not widely distributed in Africa, making it difficult to predict the daily water temperature dynamics on a local scale. Therefore, we compared two energy budget models with earlier made observations of the daily water temperature dynamics in a small, shallow and clear water pool (diameter 0.96 m, depth 0.32 m) in Kenya. This paper describes (1) a complex 1-Dimensional model, and (2) a simplified second model, and (3) shows that both models mimic the water temperature dynamics in the water pool accurately. The latter model has the advantage that it only needs common weather data (air temperature, air humidity, wind speed and cloud cover) to estimate the diurnal temperature dynamics in breeding sites of African malari
Post-yield characterisation of metals with significant pile-up through spherical indentations
Finite element simulations of spherical indentations accounting for frictional contact provide validated load–indentation output for
assessing and improving existing methods used to determine the stress–strain curve of materials with significant pile-up. The importance of friction to the proper assessment of the pile-up effect is established. Weaknesses in current characterisation relations and procedures are also identified. Existing correction formulae accounting for pile-up are modified so that the contact area radius is more accurately determined. This modification is implemented in the context of a characterisation process that relies on analysing unloading portions of load–indentation curves. Post-yield material behaviour predictions from such analysis are found to be in very good agreement with the
initial finite element material input
Recommended from our members
Small and Medium sized Enterprises’ Collaborative Buyer-Supplier Relationships: Boundary Spanning Individual Perspectives
Boundary-spanning individuals (BSIs) play a critical role in supply chain management, especially in small and medium sized enterprises (SMEs) where interactions with buyers and suppliers can depend heavily on just a few individuals. This study, utilizing data from Korean manufacturing-sector SMEs, explores whether cooperative social value orientations of SMEs’ BSIs influence the effects of collaborative buyer-supplier initiatives. The results suggested that the performance implication of decision-sharing initiative increases when BSIs have a high level of cooperative social value orientation. However, it also negatively moderates the relationship between risk/benefit sharing (involving financial losses or gains) and performance suggesting possible negative side-effects. However, we found that such orientation also negatively moderates the relationship between risk/benefit sharing (involving direct financial losses or gains) and relationship performance suggesting possible negative side-effects
- …