Convenience Foods

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The principle of equivalence and projective structure in space-times

This paper discusses the extent to which one can determine the space-time metric from a knowledge of a certain subset of the (unparametrised) geodesics of its Levi-Civita connection, that is, from the experimental evidence of the equivalence principle. It is shown that, if the space-time concerned is known to be vacuum, then the Levi-Civita connection is uniquely determined and its associated metric is uniquely determined up to a choice of units of measurement, by the specification of these geodesics. It is further demonstrated that if two space-times share the same unparametrised geodesics and only one is assumed vacuum then their Levi-Civita connections are again equal (and so the other metric is also a vacuum metric) and the first result above is recovered.Comment: 23 pages, submitted to Classical and Quantum Gravit

Snacks Habits, Needs, and Ideas

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Let's Eat Better Breakfasts

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Safety Engineering with COTS components

Safety-critical systems are becoming more widespread, complex and reliant on software. Increasingly they are engineered through Commercial Off The Shelf (COTS) (Commercial Off The Shelf) components to alleviate the spiralling costs and development time, often in the context of complex supply chains. A parallel increased concern for safety has resulted in a variety of safety standards, with a growing consensus that a safety life cycle is needed which is fully integrated with the design and development life cycle, to ensure that safety has appropriate influence on the design decisions as system development progresses. In this article we explore the application of an integrated approach to safety engineering in which assurance drives the engineering process. The paper re- ports on the outcome of a case study on a live industrial project with a view to evaluate: its suitability for application in a real-world safety engineering setting; its benefits and limitations in counteracting some of the difficulties of safety en- gineering with COTS components across supply chains; and, its effectiveness in generating evidence which can contribute directly to the construction of safety cases

Designing an online part-time Master of Philosophy with Problem Oriented Engineering

The paper reports on the application of Problem Oriented Engineering (POE) to the design of a highly innovative post-graduate research programme for the Open University, UK, a world leader in supported distance higher education. The new programme, to be launched in October 2009, is a part-time Master of Philosophy (MPhil) to be delivered entirely at a distance, supported by a blend of synchronous, asynchronous and immersive internet and web technologies. POE is a framework for engineering design under development at the Open University. After a brief description of the project and the task at hand, the paper discusses the overall engineering approach taken, key aspects of product design, the mapping between requirements and technology, and the development of one key technological component

Flight researh at NASA Ames Research Center: A test pilot's perspective

In 1976 NASA elected to assign responsibility for each of the various flight regimes to individual research centers. The NASA Ames Research Center at Moffett Field, California was designated lead center for vertical and short takeoff and landing, V/STOL research. The three most recent flight research airplanes being flown at the center are discussed from the test pilot's perspective: the Quiet Short Haul Research Aircraft; the XV-15 Tilt Rotor Research Aircraft; and the Rotor Systems Research Aircraft

An Indicator Measuring Underlying Economic Activity in Greece

Using a state space formulation developed by Stock and Watson and Garratt and Hall we construct an indicator, which then is interpreted as a measure of the underlying economic activity of the Greek economy. The chief novelty of the paper is that the underlying model is calibrated, rather than estimated, using sample information. Our approach is more flexible than the original one, in that it provides the possibility to cope with outlying observations and to evaluate particular shocks affecting the economy using judgmental interventions. The new indicator could be very helpful for short run policy analysis signalling emerging economic problems.Economic Activity; Coincident Indicator; Kalman Filter