Setting the holding cost rates in a multi-product system with remanufacturing

The Net Present Value (NPV) approach is considered to be the right approach to study inventory and production systems. But, approximate average cost (AC) approach is widely used in both practice and theory. However, the opportunity cost interpretation of AC framework is not that straightforward in systems with joint manufacturing and remanufacturing. In such systems the end-product stock contains both manufactured and remanufactured products. Remanufacturing can be used to convert the returns stock into different products. Due to this complex structure, the valuation of inventories at both stocking points is ambiguous. In this paper we analyze a two-product system with manufacturing and remanufacturing in a deterministic setting. By considering two different models under an NPV approach and an AC approach, we determine holding cost rates such that the two approaches are approximately equivalent. Then we demonstrate the negative effect of traditional valuation methodology on the remanufacturing operation dynamics by using these theoretical results

Josephson oscillation of a superfluid Fermi gas

Using the complete numerical solution of a time-dependent three-dimensional mean-field model we study the Josephson oscillation of a superfluid Fermi gas (SFG) at zero temperature formed in a combined axially-symmetric harmonic plus one-dimensional periodic optical-lattice (OL) potentials after displacing the harmonic trap along the axial OL axis. We study the dependence of Josephson frequency on the strength of the OL potential. The Josephson frequency decreases with increasing strength as found in the experiment of Cataliotti et al. [Science 293 (2001) 843] for a Bose-Einstein condensate and of the experiment of Pezze et al. [Phys. Rev. Lett. 93 (2004) 120401] for an ideal Fermi gas. We demonstrate a breakdown of Josephson oscillation in the SFG for a large displacement of the harmonic trap. These features of Josephson oscillation of a SFG can be tested experimentally.Comment: 7 pages, 10 figure