Reliability constrained capacity expansion planning of water resource systems

Two questionable features of many existing studies of capacity expansion planning problems in water resources are (1) the modelling of the expansion as a deterministic process, and (2) the lack of control over the incidence of system failure. System failure, in this presentation, is related to the occurrence of shortfalls in water supply. A sequential decision model is used as a general framework for the formulation of stochastic demand capacity expansion problems subject to reliability constraints designed to regulate the incidence of system failure. Various different types of constraint are investigated and each is incorporated into a dynamic programming solution procedure by means of Lagrangian theory. Computational examples illustrate the potential importance of using such reliability constraints in the analysis of capacity expansion problems.     

A new model for barred spiral galaxies

Computer simulations are used to demonstrate that normal spiral galaxies with symmetrically warped arms can appear to have bar and bar-within-ring structures when viewed from appropriate position angles.