68 research outputs found

    Maintenance Optimization based on Mathematical Modeling

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    Maintenance Optimization based on Mathematical Modeling

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    Project Selection in Knowledge Intensive Organizations Based on Intellectual Capital Scorecards

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    Management of intellectual capital is an important issue in knowledge intensive organizations. Part of this is the composition of the optimal project portfolio the organization will carry out in the future. Standard methods that guide this process mostly focus on project selection on the basis of expected returns. However, in many cases other strategic factors should be considered in their interdependence such as customer satisfaction, reputation, and development of core competences. In this paper we present a tool for the selection of a project portfolio, explicitly taking into account the balancing of these strategic factors. The point of departure is the intellectual capital scorecard in which the indicators are periodically measured against a target; the scores constitute the input of a programming model. From the optimal portfolio computed, objectives for management can be derived. The method is illustrated in the case of R&D departments

    Reconstructing Policy Decision-Making in the Ethiopian Seed Sector: Actors and Arenas Influencing Policymaking Process

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    In Ethiopia, new policy actors and new policy arenas have emerged as a result of major changes that took place in the political and economic system in the early 1990’s: the separation of state powers between the legislature and the executive, and the decision to move towards a market-oriented economic system. These are important changes that clear ground for better policymaking processes. However, the mere separation of power and emergency of new actors do not necessarily guarantee effectiveness of the established system, and thus need analysis. Considering policymaking as a process involving multiple actors, arenas and interactions between policy actors, this article sheds a new light on policymaking processes in Ethiopia. Focusing on the four years of discussions on developing seed law, we question whether and how the emergence of new actors and new policy arenas have influenced the process and outcome of policymaking in the Ethiopian seed sector. Our analysis reveals that the new policy arenas provided opportunities for actors to place their preferred policy options on the agenda and to get them incorporated into the draft seed law. However, decision-making ultimately remains firmly in the hands of the executive, mainly because of a blurred separation of power between the executive and the legislature. Keywords: public policy, arena, actor, legislative, executive, seed polic

    Joint Condition-based Maintenance and Condition-based Production Optimization

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    Developments in sensor equipment and the Internet of Things increasingly allow production facilities to be monitored and controlled remotely and in real-time. Organizations can exploit these opportunities to reduce costs by employing condition-based maintenance (CBM) policies. Another recently proposed option is to adopt condition-based production (CBP) policies that control the deterioration of equipment remotely and in real-time by dynamically adapting the production rate. This study compares their relative performance and introduces a fully dynamic condition-based maintenance and production (CBMP) policy that integrates both policies. Numerical results show that the cost-effectiveness of the policies strongly depends on system characteristics such as the planning time for maintenance, the cost of corrective maintenance, and the rate and volatility of the deterioration process. Integrating condition-based production decisions into a condition-based maintenance policy substantially reduces the failure risk, while fewer maintenance actions are performed. Interestingly, in some situations, the combination of condition-dependent production and maintenance even yields higher cost savings than the sum of their separate cost savings. Moreover, particularly condition-based production is able to cope with incorrect specifications of the deterioration process. Overall, there is much to be gained by making the production rate condition-dependent, also, and sometimes even more so, if maintenance is already condition-based. These insights provide managerial guidance in selecting CBM, CBP, or the fully flexible CBMP policy

    Joint Condition-based Maintenance and Load-Sharing Optimization for Multi-unit Systems with Economic Dependency

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    Many production facilities consist of multiple units of equipment, such as pumps or turbines, that are jointly used to satisfy a given production target. Such systems often have overcapacity to ensure high levels of reliability and availability. The deterioration rates of the units typically depend on their production rates, implying that the operator can control deterioration by dynamically reallocating load among units. In this study, we examine the value of condition-based load-sharing decisions for multi-unit systems with economic dependency. We formulate the system as a Markov decision process and provide optimal joint condition-based maintenance and production policies. Our numerical results show that, dependent on the system characteristics, substantial cost savings of up to 40% can be realized compared to the optimal condition-based maintenance policy under equal load-sharing. The structure of the optimal policy particularly depends on the maintenance setup cost and the penalty that is incurred if the production target is not satisfied. For systems with high setup costs, the clustering of maintenance interventions is improved by synchronizing the deterioration of the units. On the contrary, for low setup costs, the deterioration levels are desynchronized and the maintenance interventions are alternated

    Joint condition-based maintenance and load-sharing optimization for two-unit systems with economic dependency

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    Many production facilities consist of multiple and functionally exchangeable units of equipment, such as pumps or turbines, that are jointly used to satisfy a given production target. Such systems often have to ensure high levels of reliability and availability. The deterioration rates of the units typically depend on their production rates, implying that the operator can control deterioration by dynamically reallocating load among units. In this study, we examine the value of condition-based load-sharing decisions for two-unit systems with economic dependency. We formulate the system as a Markov decision process and provide optimal joint condition-based maintenance and production policies. Our numerical results show that, dependent on the system characteristics, substantial cost savings of up to 40% can be realized compared to the optimal condition-based maintenance policy under equal load-sharing. The structure of the optimal policy particularly depends on the maintenance setup cost and the penalty that is incurred if the production target is not satisfied. For systems with high setup costs, the clustering of maintenance interventions is improved by synchronizing the deterioration of the units. On the contrary, for low setup costs, the deterioration levels are desynchronized and the maintenance interventions are alternated
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