An Intelligent Traction Control for Motorcycles

The appearance of anti-lock braking systems (ABS) and traction control systems (TCS) have been some of the most major developments in vehicle safety. These systems have been evolving since their origin, always keeping the same objective, by using increasingly sophisticated algorithms and complex brake and torque control architectures. The aim of this work is to develop and implement a new control model of a traction control system to be installed on a motorcycle, regulating the slip in traction and improving dynamic performance of two-wheeled vehicles. This paper presents a novel traction control algorithm based on the use of Artificial Neural Networks (ANN) and Fuzzy Logic. An ANN is used to estimate the optimal slip of the surface the vehicle is moving on. A fuzzy logic control block, which makes use of the optimal slip provided by the ANN, is developed to control the throttle position. Two control blocks have been tuned. The first control block has been tuned according to the experience of an expert operator. The second one has been optimized using Evolutionary Computation (EC). Simulation shows that the use of EC can improve the fuzzy logic based control algorithm, obtaining better results than those produced with the control tuned only by experience.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Zaculeu, Guatemala : réflexions et propositions pour un retour local

Zaculeu is a site in the Maya highlands of Guatemala known for an aggressive reconstruction project sponsored by the United Fruit Company in the mid-twentieth centur y. Although archaeologists recovered a substantial collection of artifacts during their excavations , most of the pieces are stored in repositories in Guatemala City, far from where they were found. A small exhibition room in Zaculeu offers a modest sample of what archaeologists recovered. Taking Zaculeu as a case study, this article offers a brief reflection on importance of the history of national archaeological collections and the return to the place where they were foundZaculeu é um sitio arqueológico nas terras altas maias da Guatemala famoso por um projeto de reconstrução agressivo patrocinado pela United Fruit Company em meados do século passado. Embora os arqueólogos tenham recuperado uma coleção substancial de artefatos durante suas escavações, a maioria das peças está armazenada em repositórios na Cidade da Guatemala, longe de onde foram encontradas. Uma pequena sala de exposições em Zaculeu oferece uma pequena amostra do que os arqueólogos recuperaram. Tomando Zaculeu como caso de estudo, é feita uma breve reflexão sobre a importância da história das coleções arqueológicas nacionais e do regresso ao seu local de descobert

Reseña sobre “Artesanos y manufactureros en Lima colonial” de Francisco Quiroz

Este trabajo publicado por el BCRP y el IEP tiene como tema central el papel jugado en la ciudad de Lima por los artesanos y la producción de manufacturas en la economía colonial desde los inicios del período hasta fines del siglo XVIII.

Decentralized dynamic task allocation for UAVs with limited communication range

We present the Limited-range Online Routing Problem (LORP), which involves a team of Unmanned Aerial Vehicles (UAVs) with limited communication range that must autonomously coordinate to service task requests. We first show a general approach to cast this dynamic problem as a sequence of decentralized task allocation problems. Then we present two solutions both based on modeling the allocation task as a Markov Random Field to subsequently assess decisions by means of the decentralized Max-Sum algorithm. Our first solution assumes independence between requests, whereas our second solution also considers the UAVs' workloads. A thorough empirical evaluation shows that our workload-based solution consistently outperforms current state-of-the-art methods in a wide range of scenarios, lowering the average service time up to 16%. In the best-case scenario there is no gap between our decentralized solution and centralized techniques. In the worst-case scenario we manage to reduce by 25% the gap between current decentralized and centralized techniques. Thus, our solution becomes the method of choice for our problem

Anytime coalition structure generation on synergy graphs

We consider the coalition structure generation (CSG) problem on synergy graphs, which arises in many practical applications where communication constraints, social or trust relationships must be taken into account when forming coalitions. We propose a novel representation of this problem based on the concept of edge contraction, and an innovative branch and bound approach (CFSS), which is particularly efficient when applied to a general class of characteristic functions. This new model provides a non-redundant partition of the search space, hence allowing an effective parallelisation. We evaluate CFSS on two benchmark functions, the edge sum with coordination cost and the collective energy purchasing functions, comparing its performance with the best algorithm for CSG on synergy graphs: DyCE. The latter approach is centralised and cannot be efficiently parallelised due to the exponential memory requirements in the number of agents, which limits its scalability (while CFSS memory requirements are only polynomial). Our results show that, when the graphs are very sparse, CFSS is 4 orders of magnitude faster than DyCE. Moreover, CFSS is the first approach to provide anytime approximate solutions with quality guarantees for very large systems (i.e., with more than 2700 agents