Models for capacitated lot-sizing problem with backlogging,setup carryover and crossover

Setup operations are significant in some production environments. It is mandatory that their production plans consider some features, as setup state conservation across periods through setup carryover and crossover. The modelling of setup crossover allows more flexible decisions and is essential for problems with long setup times. This paper proposes two models for the capacitated lot-sizing problem with backlogging and setup carryover and crossover. The first is in line with other models from the literature, whereas the second considers a disaggregated setup variable, which tracks the starting and completion times of the setup operation. This innovative approach permits a more compact formulation. Computational results show that the proposed models have outperformed other state-of-the-art formulation.     

Stability and convergence of the spectral Lagrange-Galerkin method for mixed periodic/non-periodic convection-dominated diffusion problems

We present a convergence analysis of the spectral Lagrange-Galerkinmethod for mixed periodic/non-periodic convection-diffusionproblems. The scheme is unconditionally stable, independentof the diffusion coefficient, even in the case when numericalquadrature is used. The theoretical predictions are illustratedby a series of numerical experiments. For the periodic case,our results present a significant improvement on those givenby Süli & Ware (1991) SIAM J. Numer.Anal.28, 423-445).     

Suppression of auto-oscillations in wind tunnels with open working part

The results are given of an experimental investigation of the acoustic method of auto-oscillation suppression in wind tunnels of closed type with open working part.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 126–132, January–February, 1982.     

Theory of the motion of rafts on a river and capsules in a pipeline. Prandtl's paradox

A method is proposed for calculating the motion of rafts floating on the surface of a river and for long capsules within delivery pipelines. The investigation gives a quantitative estimate of Prandtl's qualitative conclusions to the effect that floating streamlined bodies can travel faster than the flow of the river (for turbulent flow regime). The calculations showed, and an experiment confirmed that the motion of a raft or barge exceeds the flow velocity on the surface of a river by approximately 1.5 times. Similar conclusions are obtained for the motion of long capsules of neutral buoyancy in the case of turbulent flow of a liquid in a pipeline. In the case of a laminar flow regime of the liquid, effects of the opposite kind occur.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 88–93, November–December, 1980.     

Dynamics of cryogenic jets: non-rayleigh breakup and onset of nonaxisymmetric motions

We report development of generators for periodic, satellite-free fluxes of monodisperse drops with diameters down to 10 microm from cryogenic liquids such as H2, N2, Ar, and Xe (and, as a reference fluid, water). While the break up of water jets can be described well by Rayleigh's linear theory, we find jet regimes for H2 and N2 which reveal deviations from this behavior. Thus, Rayleigh's theory is inappropriate for thin jets that exchange energy and/or mass with the surrounding medium. Moreover, at high evaporation rates, the axial symmetry of the dynamics is lost. When the drops pass into vacuum, frozen pellets form due to surface evaporation. The narrow width of the pellet flux paves the way towards various industrial and scientific applications.