Esther Álvarez

Framework for the dynamic scheduling of complex job shops

This paper discusses a Dynamic Scheduling (DS) problem in discrete manufacturing with a combined make-to-stock and make-to-order medium batch high range of products. Most of the available methodologies regarding production scheduling are either off-line methods or propose a whole rescheduling process in order to respond to disturbances. Nevertheless, static assumptions related to the manufacturing environment or customer orders seldom hold good in industrial manufacturing environments. In practice, it is very time-consuming to build new schedules to deal with these problems, so the use of approximate approaches is justified. On the one hand, Heuristic Rules (HRs) can provide good solutions to complex problems in real-time. On the other hand, Genetic Algorithms (GAs) can adapt to the time available to find a solution. In this paper, a comparison is made between HRs and GAs based on the results gathered from a prototype built in the context of a European project under the Growth programme.

Optimizing the Recycling Process of Electronic Appliances

Waste coming from disposed electrical and electronic equipment WEEE, also called “e-waste”, contains a growing range of electronic appliances of different types and sizes, thus representing an important environmental problem. One of the main problems in e-waste recycling is the lack of collection incentives and recycling infrastructures, as well as the high cost of material collection, handling and processing. A methodology that takes into account technical, economic, legal and environmental issues is proposed in this chapter. The parameters used by this system are the previous expertise of recycling companies, WEEE regulation and economic aspects. The simulation of the proposed solution has been analyzed, together with an economical assessment of the recycling process, in order to show the feasibility of the methodology.

A systematic approach to define the reuse process of printed circuit board's components

Reuse is an alternative to extend functional life of products, delaying its introduction into the recycling process. The main objective of this work is to present an automated approach to support the decision about the best way to disassemble electronic components in printed circuit boards (PCBs), in a non-destructive and selective mode. PCBs coming from production rejection may contain valuable and working parts, reusable in different applications with an affordable cost. In addition, removal of potentially hazardous and toxic components is taken into account. An automated dismantling station has been developed as a prototype, to assess the technical and economical feasibility of the process at an industrial scale. Toxic and potentially hazardous components have been extracted and managed according to European directives. First steps include the study of the most suitable PCBs and identification of components. Simulation is applied to decide the best method to extract parts in an automatic way, dealing with the geometry of the components, their location within the PCB, the method used for their soldering to the PCB surface, etc. Next steps deal with the design and construction of the decided solution, composed of an automatic handling device, desoldering and extracting system and functional verification of recovered components.

Collaborative dynamic scheduling approach in the extended enterprise

This paper presents an approach for dynamic scheduling that is based on the exchange of information and coordination of the production schedules composing a supply chain in order to find an effective global solution. The approach considers three communication systems based on agents: (i) a communication subsystem inside the plants, which handles the internal disruptions of a plant, (ii) an inter-plants communication subsystem, which manages the internal events of a plant that may affect the production schedules of other plants and (iii) a supply chain communication subsystem, which considers the events that can affect suppliers and / or customers. This paper shows some results of a research project that is being funded by Grant PI2008-08 from the Bask Government in Spain.

A multi-agent approach for dynamic production and distribution scheduling

In an age when enterprises are increasingly dependent on their suppliers and customers, individual companies should broaden their scope in order to include other organisations participating in the same value chain. Consequently, different parties of the chain ought to exchange information to make sound decisions in order to cut down global costs or improve customer service. This paper proposes a multi-agent approach for dynamic production and distribution scheduling in a simple supply chain. The approach is based on the continuous supervision of the active schedules and routes, in order to detect possible exceptions and apply corrective actions in a real-time and coordinated manner with other parties. Finally, the paper focuses on the design phase of the distribution stage, where the problem is mathematically formulated as a dynamic vehicle routing problem with time windows and backhauls (DVRP-TWB), and three combinatorial optimisation meta-heuristics are proposed as solving techniques.

An Integrated Production and Distribution Scheduling Approach for Exceptions Handling

In an international competitive environment, where companies can sell their products all over the world, coordination with other companies is of utmost importance, as a means to obtain an optimal utilization of their own resources and a competitive advantage over other supply chains. Nevertheless, in real world, most businesses are reluctant to share demand information or future plans with others, even if they belong to the same supply chain, the reason being that most of them see any other company as a potential competitor. This paper describes the architecture of an integrated approach for dynamic production and distribution scheduling in a supply chain with three levels; i.e., a company, its suppliers, and customers. This architecture tries to provide solutions to improve the performance of the supply chain by identifying the information that must be exchanged between nodes and developing methodologies for dynamic production and distribution scheduling in a coordinated manner. Moreover, a number of exceptions have been considered, both in production and distribution, to make the model as realistic as possible. Finally, the paper focuses on the distribution stage, where the problem is presented as a Dynamic Vehicle Routing Problem with Time Windows and Backhauls. This research is part of the PRODIS project (Grant PI2011-58, funded by the Basque Government in Spain).

Collaboration and Exceptions Management in the Supply Chain

A supply chain is a network of companies that performs the functions of procurement of materials, transformation of these materials into intermediate and finished products, and the distribution of these finished products to customers. Over the past few decades companies have been forced to react to a multitude of changing market dynamics: The increasing size of companies for attending global markets results in complex, longer and costly logistics infrastructures. The trend towards outsourcing and off-shoring has caused a fragmentation of the supply chain. Globalization means companies will have to face global managerial risks: financial crisis, environmental tsunamis, political risks, terrorist attacks. Environmental sustainability is a key consideration in the development of future globalization strategies. To sum up, a company is no more going to behave like an island. All companies are interconnected and the final service to the customer is the result of the participation of a set of companies. Therefore, it is necessary to adopt a holistic view in order to make good decisions. The objective of Supply Chain Management (SCM) is managing the entire flow of information, materials and services from raw materials suppliers through factories and warehouses to the end customer (Burt et al., 2002). SCM adds value to the customer when inventory is correctly positioned, thus facilitating sales. Besides, it helps organizations to build a suitable balance between differentiation through superior customer service and cost (Christopher, 2005). In order to manage a supply chain in a successful way, it is necessary to reduce both lead times and inventory levels, since they contribute to increase the global cost of the supply chain and harm customer service. Moreover, any delays related to a mismatch between supply and demand may cause excess of inventories and stock-outs that must be avoided. Demand variations and possible supply problems are inevitable, so it is necessary to ensure that the supply chain is responsive and flexible. Therefore, a fluent information exchange and collaboration between members of the supply chain is desirable. SCM is intrinsically linked to collaboration: not only material, information, or money flows must be managed, but also relationships that are located both upstream and downstream the chain. The purpose of this chapter is to provide an approach for collaborative dynamic scheduling that tries to coordinate different echelons of the supply chain in order to reduce inventory,