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Experimental characterization of the bulk absorption properties of sapphire, spinel, yttria, and ALON as a function of temperature is accomplished using a Bomem DA3.02 vacuum Fourier transform spectrometer and a heated cell. The measurements are performed between 2 and 20 microm from room temperatures to 775 K. Spectra of two samples of different thicknesses are ratioed to reduce surface effects and to provide a direct measure of the bulk extinction coefficient. Absorption coefficient and reflectivity data are used to determine parameters in a multiphoton absorption model. The model has proved valid up to the melting temperature of the material. This model provides an accurate means of interpolating and extrapolating the measurements to give a comprehensive characterization of intrinsic absorption properties with frequency and temperature (in the multiphonon region).

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The question whether a set of formulae Γ implies a formula ϕ is fundamental. The present paper studies the complexity of the above implication problem for propositional formulae that are built from a systematically restricted set of Boolean connectives. We give a complete complexity-theoretic classification for all sets of Boolean functions in the meaning of Post's lattice and show that the implication problem is efficiently solvable only if the connectives are definable using the constants {0, 1} and only one of {∧, ∨, ⊕}. The problem remains coNP-complete in all other cases. We also consider the restriction of Γ to singletons which makes the problem strictly easier in some cases.

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Nature of an intergranular thin−film phase in a highly non−Ohmic metal oxide varistorThe determination of stable tie lines in a ternary phase diagram through a limited number of thinfilm reactions is demonstrated. Ternary phase diagrams are then used to explain the stability of refractory metals, silicides, and nitrides during various integrated circuit processing steps. The W-Si-O, Ti-Si-O, Ti-Si-N, and Ti-AI-N systems serve as examples.

It is presumed that heat generated from a trigger cell under thermal runaway (TR) in multi-cell Li-ion batteries is transferred to adjacent cells mostly by convection of ejected hot matter (and to a lesser degree by direct contact and radiative heat transfer). Therefore, venting the energized materials (ejecta) from the battery compartment should prevent cell-to-cell TR propagation. However, engineering solutions to vent ejecta from TR of an individual cell fail to prevent TR propagation, subsequently causing battery fires. Real-time in situ FTIR spectroscopy of ejecta from a cell driven into TR demonstrates that large amounts of carbonate esters are already vented from the cell before it goes into TR. The vented hot gases cool down and condense on top of adjacent cells. Subsequently, when the trigger cell reaches TR, this condensate ignites, transferring heat and potentially driving the receiving cells into TR. Computational fluid dynamics and thermal simulations of this pathway support the experimental findings. Numerical results indicate that a fraction of the solvent vented from the trigger cell is sufficient for efficient TR propagation. Our results shed new light on thermal propagation in multi-cell Li-ion batteries and suggest novel methods to prevent TR propagation.