29 research outputs found

    A novel flexible model for lot sizing and scheduling with non-triangular, period overlapping and carryover setups in different machine configurations

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    © 2017, Springer Science+Business Media New York. This paper develops and tests an efficient mixed integer programming model for capacitated lot sizing and scheduling with non-triangular and sequence-dependent setup times and costs incorporating all necessary features of setup carryover and overlapping on different machine configurations. The model’s formulation is based on the asymmetric travelling salesman problem and allows multiple lots of a product within a period. The model conserves the setup state when no product is being processed over successive periods, allows starting a setup in a period and ending it in the next period, permits ending a setup in a period and starting production in the next period(s), and enforces a minimum lot size over multiple periods. This new comprehensive model thus relaxes all limitations of physical separation between the periods. The model is first developed for a single machine and then extended to other machine configurations, including parallel machines and flexible flow lines. Computational tests demonstrate the flexibility and comprehensiveness of the proposed models

    Mixed integer programming in production planning with backlogging and setup carryover : modeling and algorithms

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    This paper proposes a mixed integer programming formulation for modeling the capacitated multi-level lot sizing problem with both backlogging and setup carryover. Based on the model formulation, a progressive time-oriented decomposition heuristic framework is then proposed, where improvement and construction heuristics are effectively combined, therefore efficiently avoiding the weaknesses associated with the one-time decisions made by other classical time-oriented decomposition algorithms. Computational results show that the proposed optimization framework provides competitive solutions within a reasonable time

    Innovation and access to technologies for sustainable development: diagnosing weaknesses and identifying interventions in the Transnational Arena

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    Sustainable development – improving human well-being across present generations without compromising the ability of future generations to meet their own needs – is a central challenge for the 21st century. Technological innovation can play an important role in moving society toward sustainable development. However, poor, marginalized, and future populations often do not fully benefit from innovation due to their lack of market or political power to influence innovation processes. As a result, current innovation systems fail to contribute as much as they might to meeting sustainable development goals. This paper focuses on how actors and institutions operating in the transnational arena can mitigate such shortfalls. To identify the most important transnational functions required to meet sustainable development needs our analysis undertook three main steps. First, we developed a framework to diagnose blockages in the global innovation system for particular technologies. This framework was built on existing theory and new empirical analysis. On the theory side, we drew from the literatures of systems dynamics; technology and sectoral innovation systems, science and technology studies, the economics of innovation, and global governance. On the empirical front, we conducted eighteen detailed case studies of technology innovation in multiple sectors relevant to sustainable development: water, energy, health, food, and manufactured goods. We use the framework to analyze our case studies in the common language of (1) technology stocks, (2) non-linear flows between stocks substantiated by specific mechanisms, and (3) characteristics of actors and socio-technical conditions (STCs) which mediate the flows between stocks . We identify blockages in the innovation system for each of the cases, diagnosing where in the innovation system flows were hindered and which specific sets of STCs and actor characteristics were associated with these blockages. Figure E.1 displays the components of our framework and how they relate
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