1999
Authors
Alves, JC; Ferreira, JC; Albuquerque, C; Oliveira, JF; Ferreira, JS; Matos, JS;
Publication
7th IEEE Symposium on Field-Programmable Custom Computing Machines (FCCM '99), 21-23 April 1999, Napa, CA, USA
Abstract
The nesting problem consists of defining the cutting plan of a piece of raw material in smaller irregular shapes, and has applications in the apparel and footwear industries. Due to its NP-hard nature, the optimal solution can only be guaranteed by exhaustively trying all possible solutions and choosing the best one. Because this is impractical in real-life industrial problems, automatic approaches are based on optimization meta-heuristics that search for sub-optimal but good enough solutions. These optimization techniques rely on the construction and evaluation of several solutions, thus requiring heavy geometric manipulation of the irregular polygons that constitute the problem data. Efficient processing of this geometric information is thus necessary to make effective fully automatic approaches to nesting problems in industrial environments. This paper describes Fafner, an FPGA-based custom computing machine that is used to accelerate the geometric operations, that are in the core of heuristic solutions to the nesting problem. The system is used as an auxiliary processor attached to a low cost personal computer, and combines a custom programmable processor with an array of custom circuits for the processing of irregular polygons.
1999
Authors
Costa, MT; Ferreira, JS;
Publication
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH
Abstract
The paper concerns a flexible flowline scheduling problem, which arises in the footwear industry. Flexibility of the line allows for manufacturing simultaneously more products in lower quantities, but it also increases the complexity of the task of balancing the line, specially because the mix of products changes everyday. A simulation model to deal with the flexible line is developed and several job sequencing rules and different part input criteria are implemented. The impact of each rule on the quality of the schedules is measured, namely, according to makespan, productivity and average machine utilisation. Computational results concerning a real application are also presented. SIMPLE++ is the simulation language used.
1998
Authors
Ferreira, JC; Alves, JC; Albuquerque, C; Oliveira, JF; Ferreira, JS; Matos, JS;
Publication
5th IEEE International Conference on Electronics, Circuits and Systems, ICECS 1998, Surfing the Waves of Science and Technology, Lisbon, Portugal, September 7-10, 1998
Abstract
The nesting (or placement) problem is an NP-hard combinatorial problem with important industrial applications, e.g. in apparel or footwear industry. This paper describes a hardware infrastructure to accelerate the processing of the underlying geometric information. The system consists of an FPGA-based reconfigurable platform enhanced by an ASIC for the processing of irregular polygons. The paper discusses the need for such a platform, establishes the main design guidelines and describes the architecture and modes of operation of both the reconfigurable infrastructure and the dedicated IC.
1998
Authors
Azevedo, AL; Sousa, JP; Bastos, JA; Toscano, C;
Publication
GLOBALIZATION OF MANUFACTURING IN THE DIGITAL COMMUNICATIONS ERA OF THE 21ST CENTURY: INNOVATION, AGILITY, AND THE VIRTUAL ENTERPRISE
Abstract
This paper describes an <
1998
Authors
Bastos, JA; Sousa, JP;
Publication
GLOBALIZATION OF MANUFACTURING IN THE DIGITAL COMMUNICATIONS ERA OF THE 21ST CENTURY: INNOVATION, AGILITY, AND THE VIRTUAL ENTERPRISE
Abstract
The purpose of this paper is to present a new view on the problem of capacity planning in a distributed network of enterprises, i.e. in a Virtual Enterprise (VE). This view is based on a distributed planning architecture, that takes into account the requirements and characteristics of local capacity models. In order to cope with the new emerging problems that the VE are encountering, we have been designing and investigating two generic architectures of Decision Support Systems (DSS) for VE planning with capacity checking, applicable to different scenarios of distributed networks of enterprises. The first architecture is hierarchical and is based on the existence of a global decision-maker. The second one is fully distributed and is based in a multi-agent co-operative environment. This work is part of a broader project with a particular focus on the semiconductor industry.
1998
Authors
Azevedo, A; de Sousa, JP;
Publication
MANAGEMENT AND CONTROL OF PRODUCTION AND LOGISTICS, VOL 1 AND 2
Abstract
This paper describes an attempt to design an "Order Promise" system to support decision making in the so-called Virtual Enterprises. In this framework, planning and control activities are very complex, and have to take place both within the enterprise and across the whole supply network in order to achieve high levels of performance. This work is part of a broader project with a particular focus on the microelectronics industry which is a good example of Virtual Enterprise, and where a quick response to the customers needs and to unpredictable changes in production conditions is considered a major factor for success. Copyright (C) 1998 IFAC.
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