J. Duprat

The CORDIC algorithm: new results for fast VLSI implementation

After a brief survey of the CORDIC algorithm, some new results that allow fast and easy signed-digit implementation of CORDIC, without modifying the basic iteration step are given. A slight modification would make it possible to use a carry-save representation of numbers, instead of a signed-digit one. The method, called the branching CORDIC method, consists of performing in parallel two classic CORDIC rotations. It gives a constant normalization factor. An online implementation of the algorithm is proposed with an online delay equal to 5 for the sine and cosine functions. >

A RUNAWAY WOLF-RAYET STAR AS THE ORIGIN OF 26Al IN THE EARLY SOLAR SYSTEM

Establishing the origin of the short-lived radionuclide (SLR) 26Al, which was present in refractory inclusions in primitive meteorites, has profound implications for the astrophysical context of solar system formation. Recent observations that 26Al was homogeneously distributed in the inner solar system prove that this SLR has a stellar origin. In this Letter, we address the issue of the incorporation of hot 26Al-rich stellar ejecta into the cold protosolar nebula. We first show that the 26Al atoms produced by a population of massive stars in an OB association cannot be injected into protostellar cores with enough efficiency. We then show that this SLR likely originated in a Wolf-Rayet star that escaped from its parent cluster and interacted with a neighboring molecular cloud. The explosion of this runaway star as a supernova probably triggered the formation of the solar system. This scenario also accounts for the meteoritic abundance of 41Ca.

Hardwired polynomial evaluation

Abstract This paper is devoted to the evaluation of polynomials and elementary functions by special-purpose circuits. First we recall the basic results concerning the approximation of mathematical functions by polynomials (these results enable us to compute every continuous function if we are able to compute polynomials); then we describe a simple operator, suitable for VLSI implementation, which evaluates a polynomial in the range [0, 1]. Finally, we give some complexity results about the evaluation of the most usual elementary functions with our operator.

LIGHT-ELEMENT NUCLEOSYNTHESIS IN A MOLECULAR CLOUD INTERACTING WITH A SUPERNOVA REMNANT AND THE ORIGIN OF BERYLLIUM-10 IN THE PROTOSOLAR NEBULA

The presence of short-lived radionuclides in the early solar system provides important information about the astrophysical environment in which the solar system formed. The discovery of now extinct

Measurement of the {sup 24}Mg({sup 3}He,p){sup 26}Al cross section: Implication for {sup 26}Al production in the early solar system

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{gamma}-ray production by proton and {alpha}-particle induced reactions on {sup 12}C, {sup 16}O, {sup 24}Mg, and Fe

Be in calcium-aluminum-rich inclusions (CAIs) with Fractionation and Unidentified Nuclear isotope anomalies (FUN-CAIs) suggests that a baseline concentration of

gamma-ray production by proton and alpha-particle induced reactions on C-12, O-16, Mg-24, and Fe

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γ-ray production by proton and α-particle induced reactions onC12,O16,Mg24, and Fe

Be in the early solar system was inherited from the protosolar molecular cloud. In this paper, we first show that the

Accurate analysis of shallowly implanted solar wind ions by SIMS backside depth profiling

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Measurement of the 24Mg(3He, p)26Al cross section : Implication for 26Al production in the early solar system

Be recorded in FUN-CAIs cannot have been produced in situ by cosmic-ray (CR) irradiation of the FUN-CAIs themselves. We then show that trapping of Galactic CRs (GCRs) in the collapsing presolar cloud core induced a negligible