Mouloud Cherfaoui

Forecast of the Traffic and Performance Evaluation of the BMT Container Terminal (Bejaia’s Harbor)

Increasing of the traffic at the park with containers of the Bejaia harbor’s and the widening of its physical surface are not directly proportional. This is why the improvement of the productivity of the park and the good functioning of the unloading and loading system requires the specialization of the equipment and the availability of storage area which can receive the unloaded quantity, and having a configuration which will be able to adapt and answer the traffic growth. Accordingly, a first study which aimed to model the unloading process, had been realized in 2003 (Sait et al, 2007). At that time, the park with containers of the EPB (Harbor Company of Bejaia) was of 3000 ETU (Equivalent Twenty Units): 2100 ETU for the full park and 900 ETU for the empty park. The study showed that for an arrival rate of 0.55 ships/day, and a batch size of 72 ETU, the mean number of containers in the full park was of 1241 ETU. While varying the rate of the arrivals (or the batch size), the park full will be saturated for a rate of 1.0368 ships/day (or for a size of 200 ETU). This study was one of the factors that have raised awareness of the EPB to the need of creating a dedicated terminal in the treatment of container, where the birth of BMT (Bejaia Mediterranean Terminal) Company. The company began its commercial activities in July 2005. In order to ensure a good functioning of the container terminal, some performance evaluation studies are established. A first study was realized in 2007 (see Ayache et al, 2007). It had for objective the global modeling of unloading/loading process and had shown that if the number of ships (having a mean size of 170 ETU), which was of 0.83 ships/day, increases to 1.4 ships/day, the full park will undergo a saturation of 94%. In this work, we propose another modeling approach which consists to decompose the system into four independent sub-systems: the loading, the unloading, the full stock and the empty stock processes.

Stochastic Analysis of an M/G/1 Retrial Queue with FCFS

The main goal of this paper is to investigate stochastic analysis of a single server retrial queue with a First-Come-First-Served (FCFS) orbit and non-exponential retrial times using the monotonicity and comparability methods. We establish various results for the comparison and monotonicity of the underlying embedded Markov chain when the parameters vary. Moreover, we prove stochastic inequalities for the stationary distribution and some simple bounds for the mean characteristics of the system. We validate stochastic comparison method by presenting some numerical results illustrating the interest of the approach.

Quality of the Approximation of Ruin Probabilities Regarding to Large Claims

The aim of this work is to show, on the basis of numerical examples based on simulation results, how the strong stability bound on ruin probabilities established by Kalashnikov (2000) is affected regarding to different heavy-tailed distributions.

Optimal management of equipments of the BMT Containers Terminal (Bejaia’s Harbor)

The BMT (Bejaia Mediterranean Terminal) Company of Bejaia’s harbor became aware that the performances of the terminal with containers is measured by the time of stopover, the speed of the operations, the quality of the service and the cost of container’s transit. For this end, the company has devoted several studies to analyze the performance of its terminal: elaboration of a global model for the “loaded / unloaded” process, modeling of the system by another approach which consists of the decomposition of the system into four independent subsystems (namely: the “loading” process, the “unloading” process, the “full-stock” process and the “empty-stock” process - (see Aissani et al, 2009; Aissani et al, 2009). The models used in this last study describe in detail the comportment of the real systems and the obtained results given by the simulators corresponding to each model are approximately the same as the real values. It is the reason for which the company wants to exploit these models in order to determine an optimal management of its equipments.

Approximate controllability of stochastic bounds of stationary distribution of an M/G/1 queue with repeated attempts and two-phase service

ABSTRACT This paper aims to study the monotonicity properties and the stochastic controllability of some performance measures of an M/G/1 queue with repeated attempts and two-phase service. First, we prove the monotonicity of the transition operator of the embedded Markov chain relative to convex ordering. Then, we obtain comparability conditions for the distribution of the number of customers in the system. Finally, we give insensitive bounds for the stationary distribution of the embedded Markov chain of the model under consideration. To do so, we use the partial information about the aging concepts of the first essential service time distribution and the second optional service time distribution. To highlight the different obtained theoretical results, numerical examples based on simulation are provided. More precisely, we discuss numerically the conditions under which the approximation of our considered model by an M/M/1 retrial queue with exponential two-phase service is valid.

Multi-station manufacturing system analysis: theoretical and simulation study

This paper deals with a flexible multi-station manufacturing system modelled by re-entrant queueing model. Our model incorporates classical queueing systems with exponential service times and controlled arrival process under a priority service discipline. The system is decomposed into N 230 M. Boualem et al. fundamental multi-productive stations and 2N – 1 classes, a part follows the route fixed by the system, where each one is processed by N stations requiring 2N – 1 services. We assume that there is an infinite supply of work available, so that there are always parts ready for processing step 1. Our purpose in this paper is to present a detailed theoretical and simulation analysis of this priority multi-station manufacturing system.