In this review we compare the three existing sets of theoretical yields of zero metal massive stars available in the literature. We also show how each of these three different sets of yields fits the element abundance ratios observed in the extremely metal poor star CD 38 245. We find that, at present, no theoretical set of yields of zero metal massive stars is able to satisfactorily reproduce ...

We show that the existence of a Fredholm element of the zero calculus of pseudodifferential operators on a compact manifold with boundary with a given elliptic symbol is determined, up to stability, by the vanishing of the Atiyah-Bott obstruction. It follows that, up to small deformations and stability, the same symbols have Fredholm realizations in the zero calculus, in the scattering calculus...

The design and breadboard implementation of a constant-frequency, zero-voltage-switched, full-bridge pulsewidth modulation converter delivering a 12-V-at-1-kW output from a 350–450-Vdc input bus is described. The zero-voltage switching characteristic is maintained over a wide operating range by utilizing the transformer magnetizing inductance as an energy storage element. Output voltage regulat...

We design a numerical scheme for transport equations with oscillatory periodic scattering coefficients. The scheme is asymptotic preserving in the diffusion limit as Knudsen number goes to zero. It also captures the homogenization limit as the length scale of the scattering coefficient goes to zero. The proposed method is based on the construction of multiscale finite element basis and a Galerk...

D. Schurig North Carolina State University, Department of ECE, Campus Box 7911, Raleigh, NC, 27695 Abstract: Starting from the Luneberg lens index profile, we apply the transformation design method to the problem of far-field imaging of (infinitely) distant objects. This analysis yields a single element lens with a planar image surface, zero aberrations of all orders, zero F-number and (in some...

Thermoelastic triangular cell lattices composed of bi-material curved ribs were designed and analyzed by finite element simulation. Positive, negative, or zero thermal expansion was possible by varying rib curvature if joints can pivot freely, as expected. Welded or bonded joints result in nonzero expansion but smaller in magnitude than that of a constituent material having higher thermal expan...

We prove that for all q > 61, every non-zero element in the finite field Fq can be written as a linear combination of two primitive roots of Fq . This resolves a conjecture posed by Cohen and Mullen.