An overview of aerospace gas turbine technology of relevance to the development of the automotive gas turbine engine

Technology areas related to gas turbine propulsion systems with potential for application to the automotive gas turbine engine are discussed. Areas included are: system steady-state and transient performance prediction techniques, compressor and turbine design and performance prediction programs and effects of geometry, combustor technology and advanced concepts, and ceramic coatings and materials technology

Wick's Theorem for non-symmetric normal ordered products and contractions

We consider arbitrary splits of field operators into two parts, and use the corresponding definition of normal ordering introduced by Evans and Steer. In this case the normal ordered products and contractions have none of the special symmetry properties assumed in existing proofs of Wick's theorem. Despite this, we prove that Wick's theorem still holds in its usual form as long as the contraction is a c-number. Wick's theorem is thus shown to be much more general than existing derivations suggest, and we discuss possible simplifying applications of this result.Comment: 17 page

Homeowners? Repeat-Sale Gains, Dual Agency and Repeated Use of the Same Agent

Previous studies of dual agency, where one agent serves both buyer and seller in a transaction, use hedonic models. Repeat-sale methods can test for the price effect of accepting dual agency. Dual agency does not show convincing effects on expected gain, which would occur if there was a systematic bias, or on heteroscedasticity, which would occur if there are large effects that are rare. Earlier researchers could not test for the effect of an owner picking a listing agent who was the earlier selling agent. Consistently positive mean abnormal price gains come from this choice, as well as signi?cant heteroscedasticity.

Rules for transition rates in nonequilibrium steady states

Just as transition rates in a canonical ensemble must respect the principle of detailed balance, constraints exist on transition rates in driven steady states. I derive those constraints, by maximum information-entropy inference, and apply them to the steady states of driven diffusion and a sheared lattice fluid. The resulting ensemble can potentially explain nonequilibrium phase behaviour and, for steady shear, gives rise to stress-mediated long-range interactions.Comment: 4 pages. To appear in Physical Review Letter