We consider a single-stage inventory system supplying external demands and receiving stocks from an ample supply. Time is divided into periods of …xed length; a period can be a day or a week depending on the situation. In each period, demands arrive and are either …lled or backlogged. The system operates under a general periodic-review base-stock policy. Under this policy, the inventory positio...

Recently both shear turbulence and isotropic turbulence have been investigated by means of unstable periodic orbits. These orbits are embedded in a high dimensional chaotic attractor that represents the turbulent flow. In both cases, the periodic motion can be shown to bear a strong similarity to the turbulent motion. Therefore we can learn about the nature of turbulence by studying the periodi...

Let (Rn(x))n∈N0 be an orthogonal sequence inducing a polynomial hypergroup on N0. The basic facts on polynomial hypergroups and their characters can be found in the monograph [1] or in the papers [6, 7]. A recent review is [8]. The Banach space of almost periodic functions on hypergroups is introduced and studied by the author in [5]. Weakly almost periodic functions are the topic of [12]. It i...

Periodic travelling waves have been reported in a number of recent spatio-temporal field studies of populations undergoing multi-year cycles. Mathematical modelling has a major role to play in understanding these results and informing future empirical studies. We review the relevant field data and summarize the statistical methods used to detect periodic waves. We then discuss the mathematical ...