Spacecraft utility and the development of confidence intervals for criticality of anomalies

The concept of spacecraft utility, a measure of its performance in orbit, is discussed and its formulation is described. Performance is defined in terms of the malfunctions that occur and the criticality to the mission of these malfunctions. Different approaches to establishing average or expected values of criticality are discussed and confidence intervals are developed for parameters used in the computation of utility

Estimation procedures to measure and monitor failure rates of components during thermal-vacuum testing

Estimation procedures are described for measuring component failure rates, for comparing the failure rates of two different groups of components, and for formulating confidence intervals for testing hypotheses (based on failure rates) that the two groups perform similarly or differently. Appendix A contains an example of an analysis in which these methods are applied to investigate the characteristics of two groups of spacecraft components. The estimation procedures are adaptable to system level testing and to monitoring failure characteristics in orbit

Atomic final-state interactions in tritium decay

We calculate the effect of the Coulomb interaction of the ejected β ray with the bound atomic electron in the β decay of a tritium atom. The excited state probabilities of the residual helium ion are changed by at most 0.17% from the usual sudden approximation

The extension of the thermal-vacuum test optimization program to multiple flights

The thermal vacuum test optimization model developed to provide an approach to the optimization of a test program based on prediction of flight performance with a single flight option in mind is extended to consider reflight as in space shuttle missions. The concept of 'utility', developed under the name of 'availability', is used to follow performance through the various options encountered when the capabilities of reflight and retrievability of space shuttle are available. Also, a 'lost value' model is modified to produce a measure of the probability of a mission's success, achieving a desired utility using a minimal cost test strategy. The resulting matrix of probabilities and their associated costs provides a means for project management to evaluate various test and reflight strategies

Magnetic ionization fronts II: Jump conditions for oblique magnetization

We present the jump conditions for ionization fronts with oblique magnetic fields. The standard nomenclature of R- and D-type fronts can still be applied, but in the case of oblique magnetization there are fronts of each type about each of the fast- and slow-mode speeds. As an ionization front slows, it will drive first a fast- and then a slow-mode shock into the surrounding medium. Even for rather weak upstream magnetic fields, the effect of magnetization on ionization front evolution can be important. [Includes numerical MHD models and an application to observations of S106.]Comment: 9 pages, 10 figures, Latex, to be published in MNRA

Clumpy Ultracompact HII Regions I: Fully Supersonic Wind-blown Models

We propose that a significant fraction of the ultracompact HII regions found in massive star-forming clouds are the result of the interaction of the wind and ionizing radiation from a young massive star with the clumpy molecular cloud gas in its neighbourhood. Distributed mass loading in the flow allows the compact nebulae to be long-lived. In this paper, we discuss a particularly simple case, in which the flow in the HII region is everywhere supersonic. The line profiles predicted for this model are highly characteristic, for the case of uniform mass loading. We discuss briefly other observational diagnostics of these models.Comment: To appear in Monthly Notices of the Royal Astronomical Society. 5 pages LaTeX (uses mn.sty and epsf.sty macros) + 4 PS figures. Also available via http://axp2.ast.man.ac.uk:8000/Preprints.htm

Changing patterns of religious affiliation, church attendance and marriage across five areas of Europe since the early 1980s: trends and associations

This study draws on three waves of the European Values Survey (conducted between 1981 and 1984, between 1989 and 1993, and between 1999 and 2004) across five countries for which full data are available (Great Britain, Italy, the Netherlands, Northern Ireland, Spain, and Sweden) in order to address five research questions. Question one examined changes in religious affiliation. Across all five countries, the proportions of the non-affiliated increased. Question two examined changes in church attendance. Across all five countries, the proportions of the non-attenders increased. Question three examined changes in marital status. Across all five countries the proportions of the population checking the category 'married' declined, although in Spain the decline was marginal. Question four examined the association between religious affiliation and being married. The religious affiliated were more likely to be married than the non-affiliated. Question five examined the association between church attendance and being married. Weekly attenders were more likely to be married than the non-attenders. Overall these data support the close association between religion and marriage across five European countries (where there are very different religious climates) and support the hypothesis that changing religious values and changing family values go hand-in-hand