In recent decades, fuel cells have been widely used in energy generation. In a PEMFC, considering the specific application, two types of oxidants are used. Durability tests, which are highly costly products,  are of crucial importance in evaluating the lifetime of fuel cells. The purpose of the present paper is to investigate the performance of a fuel cell by changing the type of oxidant from a...

Various non deterministic aspects of object creation in database trans formations are discussed from a modeling as well as from an expressive

The authors propose the use of two new standardized measures of risk, the standardized lifetime risk and the standardized number of years of life lost. These measures maintain the advantages of standardized rates but are more readily understood without special training. In this paper, standardizing weights based on 1992 data from England and Wales are provided, and the new measures are illustra...

Ada ‘95 does not provide for a constructor mechanism with parameters for initializing newly created objects. The package Ada.Finalization provides an initialize procedure which is automatically called at object creation time, but that procedure takes only one argument, i.e. the object being operated upon. This is hardly useful, since initialization of any kind usually requires additional inform...

Since at least the dawn of history, human beings have been interested in their own origins and in the make-up of their world. Most cultures, for example, have "origins" stories in their religions and myths to explain what and who we are. But until what we call "science" gained a foothold, no explanation provided verifiable conclusions. Only with the advent of the scientific method and the ever-...

It is proven that any spherically symmetric spacetime that possesses a compact Cauchy surface and that satis es the dominant-energy and non-negative-pressures conditions must have a nite lifetime in the sense that all timelike curves in such a spacetime must have a length no greater than 10max (2m), where m is the mass associated with the spheres of symmetry. This result gives a complete resolu...

We compare multivariate aging notions of conditionally independent lifetimes with corresponding univariate aging notions of their one-dimensional marginal distributions. Let G(t|θ) (t ≥ 0) be a one-dimensional survival function indexed by θ; for simplicity’s sake, we assume here that θ is a non-negative scalar quantity; let, furthermore, Π be a probability distribution over [0,∞) and consider t...