A new approach for specifying and solving layout problems

International audienceComponent and facility layout plays an important role in the design and usability of many engineering products and systems as mechanical design, process plan, management and architecture including ship compartment layout. Generally, layout problems are formulated and solved on a case by case basis and, as far as we know, there is no general method to specify the similarities and characteristics of each problem. Then, this paper proposes an innovative generic approach in order to describe, formulate and solve layout problems. This approach suggests in particular a new classification of layout components, introducing the concept of "virtual" component. Moreover, in order to propose to the designer an optimal spatial arrangement in a reasonable time, this paper presents an interactive optimization strategy for solving layout problems

Finite elements for 2D problems of pressurized membranes

International audienceThis paper presents theoretical and numerical developments of finite elements for axisymmetric and cylindrical bending problems of pressurized membranes. The external loading is mainly a normal pressure to the membrane and the developments are made under the assumptions of follower forces, large displacements and finite strains. The numerical computing is carried out in a different way that those used by the conventional finite element approach which consists in solving the non-linear system of equilibrium equations in which appears the stiffness matrix. The total potential energy is here directly minimized, and the numerical solution is obtained by using optimization algorithms. When the derivatives of the total energy with respect to the nodal displacements are calculated accurately, this approach presents a very good numerical stability in spite of the nil bending rigidity of the membrane. Our numerical models show a very good accuracy by comparisons to analytical solutions and experimental results

Efficient multi-objective simulated annealing algorithm for interactive layout problems

International audienceThis paper presents an efficient simulated annealing algorithm for solving multi-objective layout problems where several rectangular components are placed, respecting non-overlap and non-protrusion constraints in the given space. Resolving layout problems can be very hard in some industrial cases because problems are over-constrained and computing feasible optimal layout designs are time consuming. In most practical problems, both real and virtual components exist. The virtual components represent the required accessible space allowing the user to access to the component. The virtual components can overlap with each other, while the overlap is not allowed for the real components. Considering the limited layout design space, the capacity of the layout problem is analyzed using constructive placing techniques. To explore the feasible layout space, a hybrid simulated annealing is proposed to determine the order of placement; then, a constructive placing strategy based on empty maximal space is developed. What’s more, an interactive visualization environment is introduced between the optimization and expert. The proposed algorithm is the first attempt to search feasible space of multi-objective layout design by constructive placing method

Multi-objective layout optimization of industrial environment

International audienceAn optimal layout configuration has considerable impacts on industrial engineering. The conventional layout problem aims to find the optimal arrangement of components inside the container while satisfying no component overlap and no container protrusion constraints. In this paper, we address accessibility requirements in layout problems. The novel layout model consists of components with solid and virtual parts. On the one hand, virtual spaces associated with solid components represents the accessibility of component. On the other hand, characterizing accessibility as a constraint ensures components are accessible from the container's entry. The industrial layout involves various objectives and is usually formulated as a multi-objective problem. Hence, a novel multiobjective layout optimization using constructive placement and simulated annealing, named constructive optimization, is developed. A complete layout is generated by constructive placement and evaluated by simulated annealing. It only explores the feasible space and greatly reduces the computational effort. The experimental results prove that the constructive optimization method is effective in solving the problem of industrial layout

Perceptive exploration of layout designs using an interactive genetic algorithm

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Interactive Design Optimization of Layout Problems

International audienceLayout optimization plays an important role in the field of industrial engineering. The layout problem presented here involves the real and virtual rectangular components. The real components can be the devices or buildings depending on the application. The space of accessibility associated with the real component is virtual, which allows the user to access the real component in reality, such as facility maintenance. However, most of the layout problems are NP hard. The great complexity of layout problems increase the difficulty in finding a feasible layout design in a reasonable time. To resolve these problems, we propose a hybrid constructive placing strategy which makes the search of feasible designs easier. The multi-objective application presented in this study demonstrates the effectiveness and portability of the method. Since the number of optimal layout designs can be very large, a cluster approach is followed to group all similar solutions. First, the notion of pairwise similarity indicator is introduced to analyze the similarity among the optimized layout designs. Second, the visualization of the hierarchical clustering of similarity matrix is customized. Then for each design, the user can interact with it by locally modifying the position or rotation of the component. The interactivity helps the user evaluate performance of the designs and preferable results are typically achieved

Multi-objective optimization of layout with functional constraints

International audienceThe conventional layout problem is concerned with finding the arrangements of components inside the container to optimize objectives under geometrical constraints, i.e., no component overlap and no container protrusion. In this paper, the multi-objective optimization for layout balance and component activity requirements with functional constraints is developed. Integrating the accessibility of components as functional constraints ensures components maintenance or proper operation. However, addressing the functional constraints increase the complexity of the layout optimization. A novel multi-objective optimization algorithm is proposed using the constructive placement and the simulated annealing to search for compromised solutions between the two objectives. Thereafter, a similarity indicator is defined to evaluate how similar optimized layout designs are. The experiments indicate that the proposed optimization approach performs well in ensuring accessibility and efficiently finding high-qualified solutions, where the constructive placement largely contributes to the search for alternatives satisfying constraints

Interactive modular optimization strategy for layout problems

Layout design optimization has a significant impact in the design and use of many engineering products and systems. Realworld layout problems are usually considered as complex problems because of the geometry of components, the problem density and the great number of designer’s requirements. Solving these optimization problems is a hard and time consuming task. This paper proposes an interactive modular optimization strategy which allows the designer to find optimal solutions in a short period of calculation time. This generic strategy is based on a genetic algorithm, combined with specific optimization modules. These modules improve the global performances of the algorithm. This approach is adapted to multi-objective optimization problems and interactivity between the designer and the optimization process is used to make a final choice among design alternatives. This optimization strategy is tested on a real-world application which deals with the search of an optimal spatial arrangement of a shelter