3,132 research outputs found
An Integrated Approach to Seismic Event Location: 1. Evaluating How Method of Location Affects the Volume of Groups of Hypocenters
When seismic events occur in spatially compact clusters, the volume and geometric characteristics of these clusters often provides information about the relative effectiveness of different location methods, or about physical processes occurring within the hypocentral region. This report defines and explains how to determine the convex polyhedron of minimum volume (CPMV) surrounding a set of points. We evaluate both single-event and joint hypocenter determination (JHD) relocations for three rather different clusters of seismic events: 1) nuclear explosions from Mururoa relocated using P and PKP phases reported by the ISC, 2) intermediate depth earthquakes near Bucaramanga, Colombia, relocated using P and PKP phases reported by the ISC, and 3) shallow earthquakes near Vanuatu (formerly, the New Hebrides), relocated using P and S phases from a local station network. This analysis demonstrates that different location methods markedly affect the volume of the CPMV, however, volumes for JHD relations are �not always smaller than volumes for single-event relocations.Phillips Laboratory, Directorate of Geophysics, Air Force Material Command, Hanscom Air Force Base, MassachusettsInstitute for Geophysic
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Cliff's Nodes Concerning Plotting Nodal Lines for P, Sh, and Sv
The purpose of this technical report is to provide background� information for a Fortran program package CliffsNodes.PShSv for plotting focal mechanisms and nodal lines.Institute for Geophysic
Evaluation of the Effect of Tocopherols on the Stability of Biodiesel
End of Project ReportA comprehensive study was carried out on the effects of naturally occurring tocopherols and carotenoids on the stability
of biodiesel-grade methyl esters. Commercially available tocopherols and carotenoids, α-, γ- and δ-tocopherol, carotene
and asthaxanthin, were added to destabilised methyl esters and the solutions were exposed to air at 65oC. The stabilising
effect of the added tocopherols and carotenoids was determined from the number of days needed to reach the same
increase of viscosity as destabilised methyl ester without tocopherols after 1 day. All three tocopherols stabilised methyl
esters; γ- being the most effective and α- the least. The stabilising effect of tocopherols increased with concentration up
to an optimum level. Concentrations above this level did not improve stability significantly. The stabilising effect of the
tocopherols also depended on the composition of the methyl ester; they were most effective in tallow methyl ester, and
had the least effect on sunflower methyl ester. Carotene and asthaxanthin had no effect on the stability of the methyl
esters. However an unidentified carotenoid in rape methyl ester changed the oxidation pattern by reducing rates of
peroxide and viscosity increase, without affecting overall stability
Storage stabilities of fuel grade camelina, sunflower and rapeseed methyl esters.
End of Project ReportThe storage stabilities of fuel grade camelina, sunflower and rapeseed methyl
esters were evaluated in airtight and open containers. Commercial amounts (200
litres) of the methyl esters were stored in airtight drums and sampled regularly, and
the effects of air exposure were evaluated from sixteen days laboratory-scale
accelerated storage tests at 65oC. None of the methyl esters in airtight drums
deteriorated during eighteen months of storage; composition, viscosities and free
fatty acid levels remained unchanged. The accelerated storage test in open
containers, however, indicated that exposure to air can cause rapid oxidation of
each of the three methyl esters. However, oxidation can be delayed by the
presence of tocopherols (natural antioxidants) in the methyl ester, and it can be
further delayed by the presence of an unidentified carotenoid. The exceptional
stability of rapeseed methyl ester seems to be due to a combination of relatively
high levels of Μ-tocopherol and the unidentified carotenoid. The rates of
oxidation (i.e. rate of increase of viscosity etc.) of sunflower and camelina methyl
esters were about the same, but rapeseed methyl ester oxidised slower. The
observed relative rates of oxidation could be predicted from the levels of reacting
double bonds calculated from the oxidation data, but not from iodine numbers.European Union Framework Programm
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Users Manual for TexFlex-0.5: the Texas Flexible, Practical Program Package for Locating Seismic Events.
This report is a user manual for the TexFlex program. TexFlex is a computer program writtin in Fortran language and designed to find improved locations for seismic events.Phillips Laboratory, Directorate of Geophysics, Air Force Material Command, Hanscom Air Force Base, MassachusettsInstitute for Geophysic
Factors affecting the composition and use of camelina
End of Project ReportCamelina (Camelina sativa), a member of the mustard family, is a summer
annual oilseed plant. Winter hardy types also exist. False flax and Gold of
Pleasure are the popular common names for the crop. The crop was widely
grown in Eastern Europe and Russia up to the early 1940’s but was replaced with
the introduction and widespread use of oilseed rape.
The revival of interest in camelina oil is due to its high linolenic acid (38%)
content. Linolenic acid is one of the OMEGA-3 fatty acids which are generally
found in substantial quantities only in linseed and fish oils. Camelina offers an
opportunity to supply the growing demand for high quality edible oils rich in
OMEGA-3 fatty acids.
A three year study established that camelina is a very suitable crop to grow in
Ireland, producing 2.5 t/ha of high quality seed (42-47%) with no agrochemical
inputs required. The oil contains 35 to 40% linolenic acid compared to 8% in
rape and soya oils. The oil does not deteriorate during refining or storage and
can be used in a number of oil based products such as spreads and salad
dressings.European Union Structural Funds
(EAGGF
The Potentional of Recovered Vegetable Oil and Tallow as Vehicle Fuels
End of Project ReportThe use of recovered vegetable oil (RVO) and tallow as vehicle fuels was
investigated. Two options were considered; use in unprocessed form in specially
adapted engines, and the production of biodiesel for use in unmodified engines.
Two vehicles were modified to allow the use of RVO as fuel. Their performance in
terms of power and fuel economy was acceptable, but fuel filter blockage problems
would need to be resolved and long-term effects on engine life investigated before
this approach could be recommended.
Tallow with high free-fatty-acid content was esterified by a two-stage process that
could be used in a simple plant and produce biodiesel of reasonable quality. High
ester yields were obtained in laboratory and pilot-scale trials. Problems of layer
separation remain to be resolved, and the process needs to be streamlined to allow
a high throughput to be achieved.
In comparing the costs of these fuels with each other and with mineral diesel,
allowance must be made for any differences in fuel economy and for the cost of
engine conversion kits. Including these items, the use of RVO in a converted
engine would have a slightly lower cost than its use as biodiesel. Biodiesel from
tallow is likely to be more expensive than from RVO if either ester yield or plant
capacity is significantly reduced
Degradation of LaMnO{3-y} surface layer in LaMnO{3-y}/ metal interface
We report electrical measurements showing the degradation processes of
LaMnO (LaMnO) in LaMnO/normal metal interface in both point contact and
planar-type junctions. Immediately after the preparation of the interface, the
degradation process was followed by measuring the evolution of the junction
resistance versus time. This process is characterized by the appearance of a
second maximum in the resistance vs. temperature (R-T) dependence at
temperatures lower than the Curie temperature T, at which the
metal-insulator transition occurs in the bulk. These effects are explained in
terms of the formation of a depleted interface layer in LaMnO caused by an
out-diffusion of oxygen from the manganite surface to the normal metal. This
assumption is confirmed by XPS measurement. Similar results on LaSrMnO
interfaces are also obtained.Comment: 4 pages, 3 figures, accepted for publication in Appl. Phys.
Lett.(2002
Cost reduction in bio-diesel production.
End of Project ReportAs part of a programme to assess bio-diesel production from low-cost
materials, the availability of waste oils and fats in Ireland and the EU
was assessed, and the behaviour of their esters in vehicles was
measured. The utilisation of beef tallow from BSE risk organisms
was given special attention.
Esterification of high-FFA tallow required the use of excess methanol
and base catalyst. Acidification, followed by glycerol separation and
secondary acid-catalysed esterification, brought ester yields up to
acceptable levels. The high melting point of the ester restricted its
use in vehicles to low proportions in mixes with mineral diesel.
Fuels made up from low-cost esters behaved well in vehicle trials,
even where there was a high level of dilution of the engine oil. The
only problems arose from inadequate low-temperature properties and
from suspended solids in the tallow ester.
Within the EU, there are sufficient waste oils and fats available to
greatly increase bio-diesel production. In Ireland, there is sufficient
for a small production unit
Family memories in the home: contrasting physical and digital mementos
We carried out fieldwork to characterise and compare physical and digital mementos in the home. Physical mementos are highly valued, heterogeneous and support different types of recollection. Contrary to expectations, we found physical mementos are not purely representational, and can involve appropriating common objects and more idiosyncratic forms. In contrast, digital mementos were initially perceived as less valuable, although participants later reconsidered this. Digital mementos were somewhat limited in function and expression, largely involving representational photos and videos, and infrequently accessed. We explain these digital limitations and conclude with design guidelines for digital mementos, including better techniques for accessing and integrating these into everyday life, allowing them to acquire the symbolic associations and lasting value that characterise their physical counterparts
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