7,842 research outputs found
Gas dispersion measurements using a mobile Raman lidar system
The exploitation of natural gas resources to supply energy demands has resulted in the need to engineer pipelines and plants capable of handling extremely high pressures and throughputs. Consequently, more attention has been directed to evaluating the consequences of releases of material whether accidental or deliberate in nature. An important aspect of assessing the consequences of a release is an understanding of how gas disperses in the atmosphere over a wide range of release and atmospheric conditions. The most cost effective way of providing such information is through the development and use of reliable theoretical prediction methods. The need for some form of remote sensing device was identified. The various possibilities studied led to the conclusion that LIDAR (Light Detection And Ranging) offered the most suitable method. The system designed and built is described, and its recent use in monitoring operational ventings from a high pressure transmission system is discussed
The influence of parents, places and poverty on educational attitudes and aspirations
This report aims to better understand
the relationship between young people 19s
aspirations and how they are formed.
There is a high degree of interest among politicians and policymakers
in aspirations, driven by two concerns: raising the
education and skills of the UK population, and tackling social
and economic inequality. High aspirations are often seen
as one way to address these concerns, but how aspirations
contribute to strong work and educational outcomes is not
well understood. Based on longitudinal research in three
locations in the UK, the report investigates aspirations
and contributes empirical evidence to the debate
Range vegetation type mapping and above-ground green biomass estimations using multispectral imagery
The author has identified the following significant results. Range vegetation types have been successfully mapped on a portion of the 68,000 acre study site located west of Baggs, Wyoming, using ERTS-1 imagery. These types have been ascertained from field transects over a five year period. Comparable studies will be made with EREP imagery. Above-ground biomass estimation studies are being conducted utilizing double sampling techniques on two similar study sites. Information obtained will be correlated with percent relative reflectance measurements obtained on the ground which will be related to image brightness levels. This will provide an estimate of above-ground green biomass with multispectral imagery
A random wave model for the Aharonov-Bohm effect
We study an ensemble of random waves subject to the Aharonov-Bohm effect. The
introduction of a point with a magnetic flux of arbitrary strength into a
random wave ensemble gives a family of wavefunctions whose distribution of
vortices (complex zeros) are responsible for the topological phase associated
with the Aharonov-Bohm effect. Analytical expressions are found for the vortex
number and topological charge densities as functions of distance from the flux
point. Comparison is made with the distribution of vortices in the isotropic
random wave model. The results indicate that as the flux approaches
half-integer values, a vortex with the same sign as the fractional part of the
flux is attracted to the flux point, merging with it at half-integer flux.
Other features of the Aharonov-Bohm vortex distribution are also explored.Comment: 16 pages, 5 figure
Effects of congenital hearing loss and cochlear implantation on audiovisual speech perception in infants and children
Purpose: Cochlear implantation has recently become available as an intervention strategy for young children with profound hearing impairment. In fact, infants as young as 6 months are now receiving cochlear implants (CIs), and even younger infants are being fitted with hearing aids (HAs). Because early audiovisual experience may be important for normal development of speech perception, it is important to investigate the effects of a period of auditory deprivation and amplification type on multimodal perceptual processes of infants and children. The purpose of this study was to investigate audiovisual perception skills in normal-hearing (NH) infants and children and deaf infants and children with CIs and HAs of similar chronological ages. Methods: We used an Intermodal Preferential Looking Paradigm to present the same woman\u27s face articulating two words ( judge and back ) in temporal synchrony on two sides of a TV monitor, along with an auditory presentation of one of the words. Results: The results showed that NH infants and children spontaneously matched auditory and visual information in spoken words; deaf infants and children with HAs did not integrate the audiovisual information; and deaf infants and children with CIs initially did not initially integrate the audiovisual information but gradually matched the auditory and visual information in spoken words. Conclusions: These results suggest that a period of auditory deprivation affects multimodal perceptual processes that may begin to develop normally after several months of auditory experience
Application LANDSAT imagery to geologic mapping in the ice-free valleys of Antarctica
The author has identified the following significant results. Studies in the Ice-Free Valleys are resulted in the compilation of a sizeable library of maps and publications. Rock reflectance measurements were taken during the Antarctic summer of 1973. Spectral reflectance of rocks (mostly mafic lava flows) in the McMurdo and Ice-Free Valleys areas were measured using a filter wheel photometer equipped to measure reflectances in the four Landsat bands. A series of samples were collected at regular intervals across a large differentiated, mafic sill near Lake Vida. Chemical analyses of the sample suggest that the tonal variations in this sill are controlled by changes in the iron content of the rock. False color images were prepared for a number of areas by the diazo method and with an optical multispectral biviewer. These images were useful in defining boundaries of sea ice, snow cover, and in the study of ablating glaciers, but were not very useful for rock discrimination
Enhancing SPH using moving least-squares and radial basis functions
In this paper we consider two sources of enhancement for the meshfree
Lagrangian particle method smoothed particle hydrodynamics (SPH) by improving
the accuracy of the particle approximation. Namely, we will consider shape
functions constructed using: moving least-squares approximation (MLS); radial
basis functions (RBF). Using MLS approximation is appealing because polynomial
consistency of the particle approximation can be enforced. RBFs further appeal
as they allow one to dispense with the smoothing-length -- the parameter in the
SPH method which governs the number of particles within the support of the
shape function. Currently, only ad hoc methods for choosing the
smoothing-length exist. We ensure that any enhancement retains the conservative
and meshfree nature of SPH. In doing so, we derive a new set of
variationally-consistent hydrodynamic equations. Finally, we demonstrate the
performance of the new equations on the Sod shock tube problem.Comment: 10 pages, 3 figures, In Proc. A4A5, Chester UK, Jul. 18-22 200
Some illustrations of the advantages of improved resolution in geologic studies
There are no author-identified significant results in this report
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