31,726 research outputs found
Thermal stability of some aircraft turbine fuels derived from oil shale and coal
Thermal stability breakpoint temperatures are shown for 32 jet fuels prepared from oil shale and coal syncrudes by various degrees of hydrogenation. Low severity hydrotreated shale oils, with nitrogen contents of 0.1 to 0.24 weight percent, had breakpoint temperatures in the 477 to 505 K (400 to 450 F) range. Higher severity treatment, lowering nitrogen levels to 0.008 to 0.017 weight percent, resulted in breakpoint temperatures in the 505 to 533 K (450 to 500 F) range. Coal derived fuels showed generally increasing breakpoint temperatures with increasing weight percent hydrogen, fuels below 13 weight percent hydrogen having breakpoints below 533 K (500 F). Comparisons are shown with similar literature data
The UK scheduled express coach market – its economic structure and consequent entry, exit and operation by small and medium firms
Following deregulation of the UK inter-city coach market through the 1980 Transport Act the network is now dominated by two firms giving cause to question the success of the policy and the processes enabling competitive freedom. A policy cornerstone was contestability, and though market entry by small and medium sized coach firms in the UK has not been sustained in large quantities, deregulation has arguably been successful in maintaining low prices and stimulating innovation and quality improvements. The research examines potential reasons for the lack of multiple firm activity in the UK given the freedoms afforded by the market structure and tracks changes in the market. Consolidating early academic work and filling knowledge gaps with non-academic and trade press data, the research also outlines economic market structures that characterise the market across the research period and which have influenced the success of deregulation. The research compares subsequently liberalised European markets with the UK, examining factors that have stimulated and suppressed market entry. The conclusions focus on factors that are critical to market success, such as: the requirement for a comprehensive network to maximise efficiency and reach; strong demand in both service directions; brand awareness (local level and/or nationwide); e-commerce platforms, and financial resources to mitigate losses while building market share. The research finds that entry by small and medium sized firms can only be sustained if at least one of these factors are present. In parallel the research demonstrates movement through several economic structures by each market, in-part meeting objectives set by Governments, and results in a cyclical model to show the likely lifecycle of a liberalised inter-city coach market. The research finds that settled state structures have provided such freedom that large firms may now more easily compete (retaliate) or change business models (switching the main role of competition away from the open market to new monopsonistic sub-markets) with monopoly control remaining in the open market - a policy failure perhaps but maintaining the mode as a viable competitor in the public transport mix. The main research finding is how e-commerce has shaped liberalisation, shortening early competitive phases, altering travel behaviour, and raising customer expectations – all creating new barriers for smaller firms but seeing an increase in use, reach and coverage for large firms and new opportunities for 'virtual' providers
Constraints on hot metals in the Vicinity of the Galaxy
We have searched for evidence of soft X-ray absorption by hot metals in the
vicinity of the Galaxy in the spectra of a small sample of fifteen Type I AGN
observed with the high resolution X-ray gratings on board Chandra. This is an
extension of our previous survey of hot OVII and OVIII absorbing gas in the
vicinity of the Galaxy. The strongest absorption signatures within a few
hundred km/s of their rest-frame energies are most likely due to warm absorbing
outflows from the nearest AGN, which are back-lighting the local hot gas. We
emphasize that absorption signatures in the spectra of some distant AGN that
are kinematically consistent with the recessional velocity of the AGN are most
likely to be due to hot local gas. Along the sightline towards PG 1211+143, PDS
456 and MCG-6-30-15 there is a very large absorbing Fe column density which is
kinematically consistent with absorption by hot, local Fe. The sightlines to
these three AGN pass through the limb of the Northern Polar Spur (NPS), a local
bubble formed from several supernovae which, if rich in Fe, may account for a
large local Fe column.
We obtain limits on the column density of local, highly ionized N, Ne, Mg, Si
along all of the sightlines in our sample. We correlate the column density
limits with those of highly ionized O along the same sightlines. Assuming the
hot local gas is in collisionally ionized equilibrium, we obtain limits on the
temperature and relative abundances of the metals in the hot local gas. Our
limits on the ionic column densities in the local hot gas seem to be consistent
with those observed in the hot halo gas of edge-on normal spiral galaxies.Comment: 9 pages,2 figures, MNRAS (accepted
An Assessment of Potential Detectors to Monitor the Man-made Orbital Debris Environment
Observations using NORAD radar showed that man made debris exceeds the natural environment for large objects. For short times (a few days to a few weeks) after solid rocket motor (SRM) firings in LEO, man made debris in the microparticle size range also appears to exceed the meteoroid environment. The properties of the debris population between these size regimes is currently unknown as there has been no detector system able to perform the required observations. The alternatives for obtaining data on this currently unobserved segment of the population are assessed
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East Midlands FRESA targets project
Reviewed employment and skills targets in use by organisations in the East Midlands in order to inform the development of targets for the East Midlands Framework for Employment and Skills action (FRESA). Established target development process later adopted by emda for 2006 RES. Developed criteria for applying to future selection of economic performance monitoring metrics - especially for skills, based on extant best practice, such as the Treasury's 'Green Book'
Calculations of electric currents in Europa
Electrical currents should flow in the Galilean satellite, Europa, because it is located in Jupiter's corotating magnetosphere. The possible magnitudes of these currents are calculated by assuming that Europa is a differentiated body consisting of an outer H2O layer and a silicate core. Two types of models are considered here: one in which the water is completely frozen and a second in which there is an intermediate liquid layer. For the transverse electric mode (eddy currents), the calculated current density in a liquid layer is approximately 10 to the -5/Am. For the transverse magnetic mode (unipolar generator), the calculated current density in the liquid is severely constrained by the ice layer to a range of only 10 to the -10 to -11th power/ Am, for a total H2O thickness of 100 km, provided that neither layer is less than 4 km thick. The current density is less for a completely frozen H2O layer. If transient cracks were to appear in the ice layer, thereby exposing liquid, the calculated current density could rise to a range of 10 to the -6 to 10 to the -5/Am, depending on layer thicknesses, which would require an exposed area of 10 to the -9 to 10 to the -8 of the Europa surface. The corresponding total current of 2.3x10 to the 5th power A could in 1 yr. electrolyze 7x10 to the 5th power kg of water (and more if the cells were in series), and thereby store up to 10 the 8th power J of energy, but it is not clear how electrolysis can take place in the absence of suitable electrodes. Electrical heating would be significant only if the ice-layer thickness were on the order of 1 m, such as might occur if an exposed liquid surface were to freeze over; the heating under this condition could hinder the thickening of the ice layer
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