Identifying port maritime communities: application to the Spanish case.

The aim of this paper is to detect port maritime communities sharing similar international trade patterns, by a modelisation of maritime traffic using a bipartite weighted network, providing decision-makers the tools to search for alliances or identify their competitors. Our bipartite weighted network considers two different types of nodes: one represents the ports, while the other represents the countries where there are major import/export activity from each port. The freight traffic among both types of nodes is modeled by weighting the volume of product transported. To illustrate the model, the Spanish case is considered, with the data segmented by each type of traffic for a fine tuning. A sort of link prediction is possible, finding for those communities with two or more ports, countries that are part of the same community but with which some ports do not have yet significant traffic. The evolution of the traffics is analyzed by comparing the communities in 2009 and 2019. The set of communities formed by the ports of the Spanish port system can be used to identify global similarities between them, comparing the membership of the different ports in communities for both periods and each type of traffic in particular.

Lifetime of household appliances: empirical evidence of users behaviour.

The household appliance industry is one of the most important sectors from both the economic and environmental point of view. A greater understanding of the way in which consumers of these items behave would help to better plan the recycling needs as a function of previous purchase figures. This paper presents the findings of a field survey of Spanish consumer habits with respect to different common household appliances as regards replacement time and the reasons for replacing these appliances. The methodology used is based on survival analysis; specifically, a competing risks model. A Cox proportional hazards model is also used for the sake of comparison. Our results show that as the number of people and/or persons under 18 years in the household increases, the lifetimes of some types of appliance decrease significantly. Competing risk model shows that the probability of replacing the refrigerator due to malfunction and technological obsolescence increases with the increase of family members with a higher education. We also provide the cumulative incidence function for different appliances, which can be used to forecast future demands and electrical and electronic waste generation.

A model for the reallocation of recycling containers: application to the case of glass.

From both the social as well as the economic perspective, the recycling of household waste products is of growing importance. The recycling of glass in particular is one of the most successful as far as public collaboration is concerned, as well as due to the demand for recycled material on the part of glass manufacturers. This article presents a model for designing the first stage in the reverse logistics chain, i.e. the collection of material (in our case, applying the model to the collection of glass) directly from the consumer by means of containers. The aim of this model is to determine how to distribute the recycling containers in a specific region in the most efficient way possible, taking into account the economic and sociological characteristics of the population (level of education, number of catering establishments, etc.), while attempting to maximise the material collected and reducing the logistics costs. The model has been applied to the case of the Principality of Asturias, Spain, obtaining estimations that improve the performance of the system.