Analysis of radiation heat transfer using the Radiation Element Method by Ray Emission Model, REM2, is described. The REM2 is a generalized numerical method for calculating radiation heat transfer between absorbing, emitting and scattering media and specular surfaces with arbitrary three–dimensional configurations. The ray emission model for various radiation elements is expressed by polyhedrons and polygons. Arbitrary thermal conditions can be specified for each radiation element, and generalized radiation transfer can be achieved for both of surface and volume elements by introducing a new definition of view factors. The accuracy of the present method is verified using simple configurations. A cubic participating medium with a spherical cavity covered with specular and diffuse surfaces is analyzed as an example of an arbitrary configuration. The temperature distribution shows good accuracy with a small number (45) of rays emitted from each element compared with the Monte Carlo method.

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Molecular dynamics simulations have been performed to study the collective excitation of Zr67Ni33 amorphous and liquid alloys with a pair functional potential. The spectrum and the correlation function of the particle current are calculated for longitudinal and transverse modes. The dispersion relation is estimated from the spectrum. It is related to the peak position of the static structure factor and is strongly dependent on temperature at large wavenumbers. The collective excitation is evident for the Zr-Zr correlation but not for the Ni-Ni correlation. The motion of the Zr-Zr correlation is non-localized but that of the Ni-Ni correlation is localized. The sound velocity and the Debye temperature are calculated from the dispersion relation. The calculated power spectrum agrees with the previously reported experimental result. The power spectrum of the Zr atom of the amorphous state is similar to that of the crystal state. On the other hand, the power spectrum of Ni shows an obvious difference between the amorphous and crystal states.

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