This paper focuses on the inverse problem regarding force localization in the case of non punctual impacts occurring on elastic beams. Following the identification approach proposed to solve this problem and which is based on the reciprocity theorem, the impact location characteristics were determined by using Particle Swarm Optimization algorithm. To eliminate numerical trouble due to the trivial solutions appearing in this formulation, the fitness function was customized by introducing a set of weighting coefficients. Four different formulations of the fitness function were considered and their performances with regards to the number of sensors used and their positions were analyzed. This enabled to select the best combination of weighting coefficients to be used in the context of an impact force localization process based on Particle Swarm Optimization technique. Three sensors were found to be required and comparison with Genetic Algorithm has revealed effectiveness of the proposed method in terms of accuracy and computational time.
El objetivo principal de este trabajo es estudiar el comportamiento a fluencia de dos aceros microaleados de contenido medio de carbono, en condiciones de conformado en caliente analizando su evolución microstructural a través de la dependencia del tamaño de grano recristalizado (D rec) con el parámetro de Zener-Hollomon, Z. Se observó que esta dependencia muestra un comportamiento bimodal asociado a la transición entre la recristalización dinámica cíclica y de pico simple. También, se ha observado que la variación del D rec normalizado por el vector de Burgers (b) con la tensión de estado estable ss a su vez normalizada por el modulo de cizalladura () exhibe el mismo comportamiento bimodal arriba mencionado. Debido a la complejidad de los dos aceros estudiados, el tamaño de grano recristalizado no se ajusta a la ecuación universal de Derby. Para explicar este comportamiento cabe pensar en el efecto de los precipitados y de la microestructura inicial sobre el tamaño de grano recristalizado. Palabras clave Aceros microaleados. Conformado en caliente. Comportamiento a fluencia. Tamaño de grano recristalizado. Approach to the microstructural control of two medium carbon microalloyed steels under hot forming conditions
Demand fluctuations influence the configuration of manufacturing workshops. Integration of optimal production planning via the replenishment organization, can significantly reduce the excessive ++reconfigurations number in each period and, thereafter, the global managing costs. In this paper, we discuss the joint machines Group layout design (GLD) and lot-sizing problem (LSP) in a dynamic cellular manufacturing system (DCMS). We propose a novel multi-period model to determine the best cell formation, necessary configurations over each period, and optimal production and inventory policy that minimizes intra and inter-cell material handling, holding costs, and multitasks machines relocation. We propose a novel mixed-integer programming (MIP) associated model which is then solved by using the commercial software Optimizer CPLEX. Additionally, we present a hybrid greedy randomized adaptive search procedure (GRASP) enhanced with a path relinking procedure (PR) to solve the problem. Computational results on several benchmarks and randomly generated instances show the effectiveness and the relevance of the proposed approach and highlight the integration value.INDEX TERMS Group layout design, DCMS, Lot-sizing, GRASP.
dentifying characteristics of a force generated by non punctual impact is performed to better monitor the health of the impacted structure. This can be achieved through using an implemented structural model. For composite beams, the model can be constructed by means of the finite element method. In this work, the impact is assumed to be a uniform distributed pressure and the impact location is known. Reconstructing the force signal is performed by using regularized deconvolution techniques of the Toeplitz like equation giving the answer in terms of strains as function of the input force. Here, the generalized singular value decomposition based method is used in conjunction with truncation filtering. Quality of the reconstructed force is discussed as function of the mesh size and the mode truncation order.
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