This paper presents and compares two different solution approaches to optimize the glass collection process at a single intermunicipal authority in Belgium. First, a model enhancement approach is proposed to solve a shift scheduling optimization problem integrating the construction of glass...

This paper presents a two-stage mixed integer programming approach for optimizing the skill mix and training schedule at the aircraft maintenance company Sabena Technics. Of course, when all workers are trained for all skills, cheaper workforce schedules are possible. However, the training that...

This paper presents a fast heuristic approach to optimize staffing and scheduling of the workforce at an aircraft maintenance company. Two linked Tabu Search algorithms are proposed to minimize the labour costs and to maximize employee satisfaction. To enhance the performance of the algorithm,...

Many statistics are based on functions of sample moments. Important examples are the sample variance s2(n), the sample coefficient of variation SV (n), the sample dispersion SD(n) and the non-central t-statistic t(n). The de.nition of these quantities makes clear that the vector defined by XXX...

In this paper we study the local behaviour of a characteristic of two types of shock models. In many physical systems, a failure occurs when the stress or the fatigue, represented by $\epsilon(n)$, reaches a critical level $x$. We are interested in the time $\tau(x)$ for which this happens for...

Let f be a measurable, real function defined in a neighbourhood of infinity. The function f is said to be of generalised regular variation if there exist functions h 6? 0 and g 0 such that f(xt) ? f(t) = h(x)g(t) + o(g(t)) as t ? ? for all x ? (0,?). Zooming in on the remainder term o(g(t))...

Let fX;Xi; i = 1; 2; :::g denote independent positive random variables having a common distribution function F(x) and, independent of X, let N denote an integer valued random variable. Using S(0) = 0 and S(n) = S(n ?? 1) + Xn, the random sum S(N) has distribution function G(x) = 1Xi=0 P(N =...

In this paper, we introduce a two state homogeneous Markov chain and define a geometric distribution related to this Markov chain. We define also the negative binomial distribution similar to the classical case and call it NB related to interrupted Markov chain. The new binomial distribution is...