%0 Journal Article
%T Variance Sensitivity Analysis of Parameters for Pruning of a Multilayer Perceptron: Application to a Sawmill Supply Chain Simulation Model
%A Philippe Thomas
%A Marie-Christine Suhner
%A Andr¨¦ Thomas
%J Advances in Artificial Neural Systems
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/284570
%X Simulation is a useful tool for the evaluation of a Master Production/Distribution Schedule (MPS). The goal of this paper is to propose a new approach to designing a simulation model by reducing its complexity. According to the theory of constraints, a reduced model is built using bottlenecks and a neural network exclusively. This paper focuses on one step of the network model design: determining the structure of the network. This task may be performed by using the constructive or pruning approaches. The main contribution of this paper is twofold; it first proposes a new pruning algorithm based on an analysis of the variance of the sensitivity of all parameters of the network and then uses this algorithm to reduce the simulation model of a sawmill supply chain. In the first step, the proposed pruning algorithm is tested with two simulation examples and compared with three classical pruning algorithms from the literature. In the second step, these four algorithms are used to determine the optimal structure of the network used for the complexity-reduction design procedure of the simulation model of a sawmill supply chain. 1. Introduction Simulation is a useful tool for the evaluation of planning or scheduling scenarios [1]. Indeed, simulation highlights the evolution of the machine states, WIP (work in process) and queues. This information is useful for ˇ°predictive schedulingˇ± [1] or rescheduling. Considering the theory of constraints [2], the optimization of production processes requires maximizing the utilization rate of the bottlenecks. This is the main indicator for evaluating a Master Production/Distribution Schedule (MPS). For this, a useful technique is simulating dynamic discrete events of the material flow [3]. In fact, simulation models of actual industrial cases are often very complex and modelers encounter problems of scale [4]. In addition, many works use the simplest (reduced/aggregated) models of simulation [5¨C8]. Neural networks can extract performing models from experimental data [9]. Consequently, the use of neural networks has been proposed in order to reduce simulation models [8¨C10]. To build a neural model, an important issue is determining the structure of the network. The main techniques used to control the complexity of the network are architecture selection, regularization [11, 12], early stopping [13], and training with noise [14]; the last three are closely related [14, 15]. This paper focuses on architecture selection. To determine the optimal structure of the network, two approaches can be used. The first is constructive,
%U http://www.hindawi.com/journals/aans/2013/284570/