Supercritical fuel injection system

a fuel injection system for gas turbines is described including a pair of high pressure pumps. The pumps provide fuel and a carrier fluid such as air at pressures above the critical pressure of the fuel. A supercritical mixing chamber mixes the fuel and carrier fluid and the mixture is sprayed into a combustion chamber. The use of fuel and a carrier fluid at supercritical pressures promotes rapid mixing of the fuel in the combustion chamber so as to reduce the formation of pollutants and promote cleaner burning

Application of thermoelectric aging models to polymeric insulation in cable geometry

The life expressions of models of insulation ageing are functions of temperature and field as well as material parameters. A methodology is presented that allows these models to be applied to a cable geometry in which there is a radial variation of both field and temperature. In this way material parameters can be extracted from cable data. The methodology is illustrated using one such model and the parameters deduced from cable failure distributions are compared with those obtained for thin films. This comparison allows conclusions to be drawn about how the ageing process affects specimens of the same material with different volumes

Application of polymer ageing models to power cables

Ageing models have been developed to predict the lifetime of polymeric insulation subject to electro-thermal stresses. We present here a method for applying the models to situations in which the field is not constant over the whole specimen, as for cable geometry. The method has been applied to characteristic lifetime data from AC ageing experiments on cables. The results are presented, and the effect of insulation volume upon the model parameters is discussed

Renormalized broken-symmetry Schwinger-Dyson equations and the 2PI-1/N expansion for the O(N) model

We derive the renormalized Schwinger-Dyson equations for the one- and two-point functions in the auxiliary field formulation of $\lambda \phi^4$ field theory to order 1/N in the 2PI-1/N expansion. We show that the renormalization of the broken-symmetry theory depends only on the counter terms of the symmetric theory with $\phi = 0$. We find that the 2PI-1/N expansion violates the Goldstone theorem at order 1/N. In using the O(4) model as a low energy effective field theory of pions to study the time evolution of disoriented chiral condensates one has to {\em{explicitly}} break the O(4) symmetry to give the physical pions a nonzero mass. In this effective theory the {\em additional} small contribution to the pion mass due to the violation of the Goldstone theorem in the 2-PI-1/N equations should be numerically unimportant

Design of Ge/SiGe quantum-confined Stark effect electroabsorption heterostructures for CMOS compatible photonics

We describe a combined 6×6 k.p and one-band effective mass modelling tool to calculate absorption spectra in Ge–SiGe multiple quantum well (MQW) heterostructures. We find good agreement with experimentally measured absorption spectra of Ge–SiGe MQW structures described previously in the literature, proving its predictive capability, and the simulation tool is used for the analysis and design of electroabsorption modulators. We employ strain-engineering in Ge–SiGe MQW systems to design structures for modulation at 1310 nm and 1550 nm