Let S be a set of n points in Rd in general position. A set H of k-flats is called an mk-stabber of S if the relative interior of any m-simplex with vertices in S is intersected by at least one element of H. In this paper we give lower and upper bounds on the size of minimum mk-stabbers of point sets in Rd and in general position. We study mainly mk-stabbers in the plane and in R3.

The design and operation of a differential polymer electrolyte membrane (PEM) fuel cell is described. The fuel cell design is based on coupled stirred tank reactors (STRs) coupled through a membrane; the gas phase in each reactor compartment is well mixed. The characteristic times for reactant flow, gas phase diffusion, and reaction were chosen so that the gas compositions at both the anode and...

If the reliability of a source of testimony is open to question, it seems epistemically illegitimate to verify the source’s reliability by appealing to that source’s own testimony. Is this because it is illegitimate to trust a questionable source’s testimony on any matter whatsoever? Or is there a distinctive problem with appealing to the source’s testimony on the matter of that source’s own re...

A patient had extensive blunt trauma from a high-speed crash in which nitromethane fuel erupted from the fuel tank and soaked into his protective multilayer jumpsuit. The clinical diagnosis was complicated because the absorption of nitromethane fuel through the skin and by inhalation falsely increased the serum creatinine value when a modified Jaffe reaction was used in the laboratory. This spu...

Challenges facing fuel cell hybrid vehicles is in implementing a control strategy to find the optimal split of power between the different power sources. This paper proposes a mathematical model of power flow in such vehicles taking into consideration power train losses. Linear programming locates the global optimum indicating the finest synchronization among power units in an attempt to lower ...

Renewable energy sources are becoming more important as the world’s supply of fossil fuels decrease and also due to environmental concerns. Since 2003, when the ethanol-gasoline flex fuel car became commercially available in Brazil, the growth of this market has been significant, to the point where currently 40% of the fuel consumption in Brazil is from renewable biofuels. This has been made po...