9,275 research outputs found
Measurement of anharmonicity of phonons in negative thermal expansion compound Zn(CN)2 by high pressure inelastic neutron scattering
Zn(CN)2 is known to have an isotropic negative thermal expansion (NTE)
coefficient (about -51 x 10-6 K-1) over 10-370 K that is twice as large as that
of ZrW2O8. We have measured the pressure dependence of the phonon spectra up to
30 meV from a polycrystalline sample of Zn(CN)2 at pressures of 0, 0.3, 1.9 and
2.8 kbar at temperatures of 165 and 225 K. The measurements enabled us to
estimate the energy dependence of the ratios Gamma/B (Gamma are Gruneisen
parameters as a function of phonon energy Ei at ambient pressure and B is the
bulk modulus), which reflect the anharmonicity of phonons. We conclude that the
phonon modes of low energy below 15 meV play an important role in the
understanding of the NTE behavior in Zn(CN)2 and the measured anharmonicity can
quantitatively explain the NTE.Comment: 5 pages, 4 figure
The UARS and open data concept and analysis study
Alternative concepts for a common design for the UARS and OPEN Central Data Handling Facility (CDHF) are offered. Costs for alternative implementations of the UARS designs are presented, showing that the system design does not restrict the implementation to a single manufacturer. Processing demands on the alternative UARS CDHF implementations are then discussed. With this information at hand together with estimates for OPEN processing demands, it is shown that any shortfall in system capability for OPEN support can be remedied by either component upgrades or array processing attachments rather than a system redesign. In addition to a common system design, it is shown that there is significant potential for common software design, especially in the areas of data management software and non-user-unique production software. Archiving the CDHF data are discussed. Following that, cost examples for several modes of communications between the CDHF and Remote User Facilities are presented. Technology application is discussed
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