1,564 research outputs found
Technology and the Energy Crisis: An Assessment of the Interrelationship and the Impact
This paper presents an assessment of past and present technological innovations and research related to the present energy crisis-the impact and the interrelationship. In particular, it surveys the development of tidal power plants with particular emphasis on the past and present status of the Passamaquoddy-Cobscook Bay Dam Project. It exam1nes the benefits and environmental effects associated with tidal power development, and explores the causes and effects of the tides. It concludes w1th a brief detail of the feasibility of other renewable sources of energy-and of the impact of technological developments on marine and international affairs
Crystal nucleation mechanism in melts of short polymer chains under quiescent conditions and under shear flow
We present a molecular dynamics simulation study of crystal nucleation from
undercooled melts of n-alkanes, and we identify the molecular mechanism of
homogeneous crystal nucleation under quiescent conditions and under shear flow.
We compare results for n-eicosane(C20) and n-pentacontahectane(C150), i.e. one
system below the entanglement length and one above. Under quiescent conditions,
we observe that entanglement does not have an effect on the nucleation
mechanism. For both chain lengths, the chains first align and then straighten
locally. Then the local density increases and finally positional ordering sets
in. At low shear rates the nucleation mechanism is the same as under quiescent
conditions, while at high shear rates the chains align and straighten at the
same time. We report on the effects of shear rate and temperature on the
nucleation rates and estimate the critical shear rates, beyond which the
nucleation rates increase with the shear rate. We show that the viscosity of
the system is not affected by the crystalline nuclei.Comment: 9 page
The Early Crystal Nucleation Process in Hard Spheres shows Synchronised Ordering and Densification
We investigate the early part of the crystal nucleation process in the hard
sphere fluid using data produced by computer simulation. We find that hexagonal
order manifests continuously in the overcompressed liquid, beginning
approximately one diffusion time before the appearance of the first
`solid-like' particle of the nucleating cluster, and that a collective influx
of particles towards the nucleation site occurs simultaneously to the ordering
process: the density increases leading to nucleation are generated by the same
individual particle displacements as the increases in order. We rule out the
presence of qualitative differences in the early nucleation process between
medium and low overcompressions, and also provide evidence against any
separation of translational and orientational order on the relevant
lengthscales
Who wrote the Letter to the Hebrews? - Data mining for detection of text authorship
© 2005 COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. Copyright 2005 Society of Photo-Optical Instrumentation Engineers. This paper was published in Smart Structures, Devices, and Systems II, edited by Said F. Al-Sarawi, Proceedings of SPIE Vol. 5649 and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.This paper explores the authorship of the Letter to the Hebrews using a number of different measures of relationship between different texts of the New Testament. The methods used in the study include file zipping and compression techniques, prediction by the partial matching technique and the word recurrence interval technique. The long term motivation is that the techniques employed in this study may find applicability in future generation web search engines, email authorship identification, detection of plagiarism and terrorist email traffic filtration.Madeleine Sabordo, Shong Y. Chai, Matthew J. Berryman, and Derek Abbot
Geometry of Frictionless and Frictional Sphere Packings
We study static packings of frictionless and frictional spheres in three
dimensions, obtained via molecular dynamics simulations, in which we vary
particle hardness, friction coefficient, and coefficient of restitution.
Although frictionless packings of hard-spheres are always isostatic (with six
contacts) regardless of construction history and restitution coefficient,
frictional packings achieve a multitude of hyperstatic packings that depend on
system parameters and construction history. Instead of immediately dropping to
four, the coordination number reduces smoothly from as the friction
coefficient between two particles is increased.Comment: 6 pages, 9 figures, submitted to Phys. Rev.
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