Metaheuristic strategies for scheduling problems with uncertainty

Scheduling problems have formed an important body of research during the last decades. A scheduling problem consists in scheduling a set of jobs {J1, . . . , Jn} on a set of physical resources or machines {M1, . . . , Mm}. Each job Ji is composed of m tasks or operations {θi1, . . . , θim} with processing time pij . At the same time, we usually have constraints that establish that two task belonging to the same job cannot overlap their execution in time and that each task requires the uninterrupted and exclusive use of one of the machines for its whole processing time. Depending on the additional constraints we define, we may obtain different families of problems. The most popular in the literature are the job shop (JSP), the open shop (OSP) and the flow shop (FSP) but there exists also variants of them as the flexible job shop (FJSP) among others. Commonly, the objective function to optimise is the earliest time in which all jobs can be finished or makespan. However many other objectives may be optimised, being the most popular the tardiness, the idleness and the total flow time. In classical scheduling problems all input data are assumed to be well defined and all constraints are assumed to be hard, which is not so common in real-life applications. To reduce the gap between theory and practice, this thesis focuses on solving scheduling problems considering that uncertainty and vagueness. For instance, we shall consider uncertain task durations as well as flexible due-date constraint

Swarm lexicographic goal programming for fuzzy open shop scheduling

In this work we consider a multiobjective open shop scheduling problem with uncertain processing times and flexible due dates, both modelled using fuzzy sets. We adopt a goal programming model based on lexicographic multiobjective optimisation of both makespan and due-date satisfaction and propose a particle swarm algorithm to solve the resulting problem. We present experimental results which show that this multiobjective approach achieves as good results as single-objective algorithms for the objective with the highest priority, while greatly improving on the second objectiv

Synthesis of new conjugated mesomeric betaines from alkoxycarbonylazinium salts

A new series of conjugated mesomeric betaines have been synthesized from the reaction of various aminoheterocycles with 2-methylthio-4-oxo-3-phenylpyrido[2,1-φ][1,2,4]triazinium iodide, itself prepared from 2-ethoxycarbonylpyridinium N-aminide. Some of the heterobetaines and salts obtained have been studied by 1H-NMR, and their structures have been confirmed by X-ray analysis. The crystal structures reveal unexpected complementary stabilizing interactions between some betaines and their salts.We wish to express our thanks to the Comisió Interdepartamental de Reçerca i Innovació Tecnológica (CIRIT) for financial support (Project QFN94-4619) and to the Ministerio de Educación y Ciencia for a grant to one of us (JVM)

Ticuna Ceramics Amidst the Expansion of Illicit Coca: Rendering New Relations

In Ticuna communities across Amazonia, ceramics are useful objects employed for cooking and storage. Their practical importance, however, does not describe the extent of their significance. In the following article, we consider Ticuna ceramics and ceramic-making practices as a means of studying the changes set in motion by the transformation of Ticuna ancestral lands in Peru’s lowland Amazonian region into zones of illicit coca cultivation. Drawing on mixed-methods ethnographic research, including participant observation, interviews, and a participatory film project focused on ceramic production, we evaluate contemporary practices of ceramic-making within three Peruvian Ticuna communities in the context of these transformations, and the national government’s subsequent responses to the coca situation. Ceramics are a starting point to explore a complex web of relations as Ticuna communities intersect with both drug-trafficking operations and agents of the Peruvian state

Doñana, diversidad y ciencia

144 páginasLa biodiversidad es más que la suma de los elementos que componen el mundo vivo; también son biodiversidad las relaciones entre esos elementos, los procesos ecológicos que hacen posible su existencia y los procesos evolutivos que los han originado. […] Los seres humanos necesitamos a la biodiversidad más que ella a nosotros, ya que es la responsable de que la Tierra funcione de una manera satisfactoria. […] El entramado de la vida se ocupa de regular la composición de la atmósfera (y con ella, el clima), de depurar el aire y el agua, de hacer fértil al suelo, de evitar riadas y avalanchas, de polinizar las cosechas, de reducir las plagas, etc. Por todo ello es indispensable conservar la biodiversidad, hoy amenazada.” (Miguel Delibes) Doñana, diversidad y ciencia es un paseo conceptual por el espacio natural más emblemático de Europa. La esencia de un mito a través de decenas de fotografías… Un acercamiento respetuoso a la diversidad de sus conceptos, un paseo por la esencia de su historia y una curiosa aproximación a la ciencia que genera hoy en día. En este recorrido descubriremos el carácter distintivo de algunos de los parajes de la reserva, sus matices más interesantes, las texturas y las formas más sorprendentes de la naturaleza, sus colores y conjuntos, sus transformaciones en las últimas décadas y la influencia de la presencia humana en el privilegiado ecosistema de la Reserva Biológica de Doñana