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

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

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$_{3-y}$ (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$_c$, 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$_{3-y}$ 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