Advanced rotary engine studies

A review of rotary engine developments relevant to a stratified charge rotary aircraft engine is presented. Advantages in module size and weight, fuel efficiency, reliability, and multi-fuel capability are discussed along with developments in turbocharging, increased mean effective pressure, improved apex seal/trochoid wear surfacing materials, and high strength and temperature aluminum casting alloys. A carbureted prototype aircraft engine is also described

An explicit derivation of the Mobius function for Bruhat order

We give an explicit nonrecursive complete matching for the Hasse diagram of the strong Bruhat order of any interval in any Coxeter group. This yields a new derivation of the Mobius function, recovering a classical result due to Verma.Comment: 9 pages; final versio

The structure and evolution of X-ray clusters of galaxies

The structure of clusters is described from observations at the Einstein Observatory. It was concluded that the nature of the X-ray emission is complex and varies from broad and highly clumped to smooth and centrally peaked. The clusters whose emission is clumped tend to be rich in spirals and to have X-ray temperatures in the few kilovolt range and low velocity dispersions. The smooth centrally peaked clusters are spiral poor, and have higher temperatures and larger velocity dispersions. For many of the clusters, the emission is irregular and cannot be described by the simple, spherically symmetric models for a hot isothermal or adiabatic gas. For these clusters, the low density, intracluster gas is influenced by the potential of individual bright galaxies

How advertising through the ages has shaped Christmas

By the 20th century, mass advertising became commonplace. Consumer messages were now broadcast to the public through billboards, magazines, radio, and later the moving image of television. Mass advertising was what allowed the slowly developing idea of Christmas as a time to give gifts to go mainstream, and eventually, to define Christmas itself

Miller's Equilibrium and Uncertainty.

This paper highlights the arbitrage by firms in Miller's (1977) equilibrium when consumers face (short) selling constraints to restrict tax arbitrage. In this competitive equilibrium firms create risky tax-preferred securities that divide investors into strict tax clienteles; any changes in debt-equity ratios by individual firms have no real effects on consumers because other firms undo them.CAPITAL ; BUSINESS FINANCING ; ARBITRAGE

On a class of distributions with simple exponential tails

A simple general construction is put forward which covers many unimodal univariate distributions with simple exponentially decaying tails (e.g. asymmetric Laplace, log F and hyperbolic distributions as well as many new models). The proposed family is a special subset of a regular exponential family, and many properties flow therefrom. Two main practical points are made in the context of maximum likelihood fitting of these distributions to data. The first of these is that three, rather than an apparent four, parameters of the distributions suffice. The second is that maximum likelihood estimation of location in the new distributions is precisely equivalent to a standard form of kernel quantile estimation, choice of kernel being equivalent to specific choice of model within the class. This leads to a maximum likelihood method for bandwidth selection in kernel quantile estimation, but its practical performance is shown to be somewhat mixed. Further distribution theoretical aspects are also pursued, particularly distributions related to the main construction as special cases, limiting cases or by simple transformation