We present a hybridization of two different approaches applied to the well-known Capacitated Facility Location Problem (CFLP). The Artificial Bee algorithm (BA) is used to select a promising subset of locations (warehouses) which are solely included in the Mixed Integer Programming (MIP) model. Next, the algorithm solves the subproblem by considering the entire set of customers. The hybrid implementation allows us to bypass certain inherited weaknesses of each algorithm, which means that we are able to find an optimal solution in an acceptable computational time. In this paper we demonstrate that BA can be significantly improved by use of the MIP algorithm. At the same time, our hybrid implementation allows the MIP algorithm to reach the optimal solution in a considerably shorter time than is needed to solve the model using the entire dataset directly within the model. Our hybrid approach outperforms the results obtained by each technique separately. It is able to find the optimal solution in a shorter time than each technique on its own, and the results are highly competitive with the state-of-the-art in large-scale optimization. Furthermore, according to our results, combining the BA with a mathematical programming approach appears to be an interesting research area in combinatorial optimization.

No abstract

No abstract

Cameras are one of the most relevant sensors in autonomous robots. One challenge with them is to manage the small field of view of regular cameras. A method of coping with this, similar to the attention systems in humans, is to use mobile cameras to cover all the robot surroundings and to perceive all the objects of interest to the robot tasks even if they do not lie in the same snapshot. A gaze control algorithm is then required that continuously selects where the camera should look. This paper presents three different covert attention mechanisms that have been designed and compared: one based on round-Robin sharing, another based on dynamic salience and one with fixed pattern camera movements. Several experiments have been performed with a humanoid robot in order to validate them and to give an objective comparison in the context of RoboCup, where the robots have several perceptive needs like localization and object tracking that must be satisfied and may not be fully compatible.