UERJ - Universidade do Estado do Rio de Janeiro / Rio de Janeiro State University
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Papers by Hacène Ouzia
Improving degree of cure in pultrusion process by optimizing die-temperature
Pultrusion is a continuous process for manufacturing polymer composite with uniform cross-section... more Pultrusion is a continuous process for manufacturing polymer composite with uniform cross-sectional profiles. In this process the die temperature process variable can be used to improve the chemical and mechanical properties of the polymer composite. Several works have been done regarding simulation tools for pultrusion analysis. Usually, the development of manufacturing processes is mostly a trial-and-error exercise. However, few studies focus on optimizing this manufacturing process. In this paper, the pultrusion process of a glass fibre-epoxy set with different geometries are simulated by using a three-dimensional finite element-nodal control volume (FE/NCV) approach, a quadratic programming algorithm and a particle swarm heuristic was used to optimize the manufacturing process. The aim is to show that to optimize pultrusion process, quadratic programming algorithm can also be very efficient in finding the optimal distribution of the temperature in the pultruded material. The sec...
In this paper, we study the efficiency (both theoretically and computationally) of a class of val... more In this paper, we study the efficiency (both theoretically and computationally) of a class of valid inequalities for the minimum weighted elementary directed cycle problem (MWEDCP) in planar digraphs with negative weight elementary directed cycles. These valid inequalities are called cycle valid inequalities and are parametrized by an integer called inequality's order. From a theoretical point of view, we prove that separating cycle valid inequalities of order 1 in planar digraph can be done in polynomial time. From a computational point of view, we present a cutting plane algorithm featuring the efficiency of a lifted form of the cycle valid inequalities of order 1. In addition to these lifted valid inequalities, our algorithm is also based on a mixed integer linear formulation of the MWEDCP. The computational results are carried out on randomly generated planar digraph instances of the MWEDCP. For all 29 instances considered, we obtain in average 26.47% gap improvement. Moreover, for some of our instances the strengthening process directly displays the optimal integer elementary directed cycle.
Improving degree of cure in pultrusion process by optimizing die-temperature
Pultrusion is a continuous process for manufacturing polymer composite with uniform cross-section... more Pultrusion is a continuous process for manufacturing polymer composite with uniform cross-sectional profiles. In this process the die temperature process variable can be used to improve the chemical and mechanical properties of the polymer composite. Several works have been done regarding simulation tools for pultrusion analysis. Usually, the development of manufacturing processes is mostly a trial-and-error exercise. However, few studies focus on optimizing this manufacturing process. In this paper, the pultrusion process of a glass fibre-epoxy set with different geometries are simulated by using a three-dimensional finite element-nodal control volume (FE/NCV) approach, a quadratic programming algorithm and a particle swarm heuristic was used to optimize the manufacturing process. The aim is to show that to optimize pultrusion process, quadratic programming algorithm can also be very efficient in finding the optimal distribution of the temperature in the pultruded material. The sec...
In this paper, we study the efficiency (both theoretically and computationally) of a class of val... more In this paper, we study the efficiency (both theoretically and computationally) of a class of valid inequalities for the minimum weighted elementary directed cycle problem (MWEDCP) in planar digraphs with negative weight elementary directed cycles. These valid inequalities are called cycle valid inequalities and are parametrized by an integer called inequality's order. From a theoretical point of view, we prove that separating cycle valid inequalities of order 1 in planar digraph can be done in polynomial time. From a computational point of view, we present a cutting plane algorithm featuring the efficiency of a lifted form of the cycle valid inequalities of order 1. In addition to these lifted valid inequalities, our algorithm is also based on a mixed integer linear formulation of the MWEDCP. The computational results are carried out on randomly generated planar digraph instances of the MWEDCP. For all 29 instances considered, we obtain in average 26.47% gap improvement. Moreover, for some of our instances the strengthening process directly displays the optimal integer elementary directed cycle.
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Papers by Hacène Ouzia