16,102 research outputs found

    Production planning under dynamic product environment: a multi-objective goal programming approach

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    Production planning is a complicated task that requires cooperation among multiple functional units in any organization. In order to design an efficient production planning system, a good understanding of the environment in terms of customers, products and manufacturing processes is a must. Although such planning exists in the company, it is often incorrectly structured due to the presence of multiple conflicting objectives. The primary difficulty in modern decision analysis is the treatment of multiple conflicting objectives. A formal decision analysis that is capable of handling multiple conflicting goals through the use of priorities may be a new frontier of management science. The objective of this study is to develop a multi objective goal programming (MOGP) model to a real-life manufacturing situation to show the trade-off between different some times conflicting goals concerning customer, product and manufacturing of production planning environment. For illustration, two independent goal priority structures have been considered. The insights gained from the experimentation with the two goal priority structures will guide and assist the decision maker for achieving the organizational goals for optimum utilization of resources in improving companies competitiveness. The MOGP results of the study are of very useful to various functional areas of the selected case organization for routine planning and scheduling. Some of the specific decision making situations in this context are: (i). the expected quality costs and production costs under identified product scenarios, (ii).under and over utilization of crucial machine at different combinations of production volumes, and (iii). the achievement of sales revenue goal at different production volume combinations. The ease of use and interpretation make the proposed MOGP model a powerful communication tool between top and bottom level managers while converting the strategic level objectives into concrete tactical and operational level plans.

    The new Dutch timetable: The OR revolution

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    In December 2006, Netherlands Railways introduced a completely new timetable. Its objective was to facilitate the growth of passenger and freight transport on a highly utilized railway network, and improve the robustness of the timetable resulting in less train delays in the operation. Further adjusting the existing timetable constructed in 1970 was not option anymore, because further growth would then require significant investments in the rail infrastructure. Constructing a railway timetable from scratch for about 5,500 daily trains was a complex problem. To support this process, we generated several timetables using sophisticated operations research techniques, and finally selected and implemented one of these timetables. Furthermore, because rolling-stock and crew costs are principal components of the cost of a passenger railway operator, we used innovative operations research tools to devise efficient schedules for these two resources. The new resource schedules and the increased number of passengers resulted in an additional annual profit of 40 million euros (60million)ofwhichabout10millioneuroswerecreatedbyadditionalrevenues.Weexpectthistoincreaseto70millioneuros(60 million) of which about 10 million euros were created by additional revenues. We expect this to increase to 70 million euros (105 million) annually in the coming years. However, the benefits of the new timetable for the Dutch society as a whole are much greater: more trains are transporting more passengers on the same railway infrastructure, and these trains are arriving and departing on schedule more than they ever have in the past. In addition, the rail transport system will be able to handle future transportation demand growth and thus allow cities to remain accessible. Therefore, people can switch from car transport to rail transport, which will reduce the emission of greenhouse gases.

    Evaluation of Cognitive Architectures for Cyber-Physical Production Systems

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    Cyber-physical production systems (CPPS) integrate physical and computational resources due to increasingly available sensors and processing power. This enables the usage of data, to create additional benefit, such as condition monitoring or optimization. These capabilities can lead to cognition, such that the system is able to adapt independently to changing circumstances by learning from additional sensors information. Developing a reference architecture for the design of CPPS and standardization of machines and software interfaces is crucial to enable compatibility of data usage between different machine models and vendors. This paper analysis existing reference architecture regarding their cognitive abilities, based on requirements that are derived from three different use cases. The results from the evaluation of the reference architectures, which include two instances that stem from the field of cognitive science, reveal a gap in the applicability of the architectures regarding the generalizability and the level of abstraction. While reference architectures from the field of automation are suitable to address use case specific requirements, and do not address the general requirements, especially w.r.t. adaptability, the examples from the field of cognitive science are well usable to reach a high level of adaption and cognition. It is desirable to merge advantages of both classes of architectures to address challenges in the field of CPPS in Industrie 4.0

    Methodological review of multicriteria optimization techniques: aplications in water resources

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    Multi-criteria decision analysis (MCDA) is an umbrella approach that has been applied to a wide range of natural resource management situations. This report has two purposes. First, it aims to provide an overview of advancedmulticriteriaapproaches, methods and tools. The review seeks to layout the nature of the models, their inherent strengths and limitations. Analysis of their applicability in supporting real-life decision-making processes is provided with relation to requirements imposed by organizationally decentralized and economically specific spatial and temporal frameworks. Models are categorized based on different classification schemes and are reviewed by describing their general characteristics, approaches, and fundamental properties. A necessity of careful structuring of decision problems is discussed regarding planning, staging and control aspects within broader agricultural context, and in water management in particular. A special emphasis is given to the importance of manipulating decision elements by means ofhierarchingand clustering. The review goes beyond traditionalMCDAtechniques; it describes new modelling approaches. The second purpose is to describe newMCDAparadigms aimed at addressing the inherent complexity of managing water ecosystems, particularly with respect to multiple criteria integrated with biophysical models,multistakeholders, and lack of information. Comments about, and critical analysis of, the limitations of traditional models are made to point out the need for, and propose a call to, a new way of thinking aboutMCDAas they are applied to water and natural resources management planning. These new perspectives do not undermine the value of traditional methods; rather they point to a shift in emphasis from methods for problem solving to methods for problem structuring. Literature review show successfully integrations of watershed management optimization models to efficiently screen a broad range of technical, economic, and policy management options within a watershed system framework and select the optimal combination of management strategies and associated water allocations for designing a sustainable watershed management plan at least cost. Papers show applications in watershed management model that integrates both natural and human elements of a watershed system including the management of ground and surface water sources, water treatment and distribution systems, human demands,wastewatertreatment and collection systems, water reuse facilities,nonpotablewater distribution infrastructure, aquifer storage and recharge facilities, storm water, and land use

    Decision support systems for large dam planning and operation in Africa

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    Decision support systems/ Dams/ Planning/ Operations/ Social impact/ Environmental effects

    Review of integrated approaches to river basin, planning, development and management

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    Piecemeal approaches to river basin development and management may not fully recognize the interactions and interdependence among components of a river basin system. River basin management that focuses on a single water use, on a single sector, or on the supply to particular segment of the basin population may inadvertently disrupt other sectors of the economy (in time or space). Hence, advocating for a systems approach to river basin development - for models that could help account for a river basin's key components and help address various objectives. The authors review the literature on such economic models, including models that deal with issues of water quality and quantity or with environmental considerations, recreational demand, countrywide planning, and multiple objective planning. Their review may serve as a source of references for those who need to consider whether they can use a model. Readers can evaluate the suitability, advantages, and disadvantages of particular modeling approaches for specific objectives.Water Conservation,River Basin Management,Water and Industry,Environmental Economics&Policies,Decentralization,Environmental Economics&Policies,Water Conservation,Water Supply and Sanitation Governance and Institutions,Water and Industry,Town Water Supply and Sanitation

    Conflicting interests of ecosystem services: Multi-criteria modelling and indirect evaluation of trade-offs between monetary and non-monetary measures

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    Ecosystems provide services for many stakeholder groups, often with a conflict of interests that hampers sustainability. Core to these conflicts is the challenge of trading-off monetary and non-monetary measures. Using the boreal forest as a case, we present a socio-ecologically integrated trade-off model for partly competing services (wood, game hunting, livestock grazing). Drawing on multi-criteria analyses (MCA), we found that wood production unequivocally yielded the highest net present value, but led to a substantial reduction in the performance of hunting and grazing. By imposing multiuse conditions set as minimum performance of the less profitable services, we evaluated the opportunity costs of multiuse without directly pricing non-commodities. We also quantified normalized indices of realized performance potential to evaluate the cost of multiuse with a single, joint metric. Both approaches consistently showed that accepting a rather small loss in one service may secure large gains in other services. By democratically providing a combined monetary and non-monetary evaluation, our approach should facilitate broader acceptance for the decisional metrics among stakeholders. It thereby has the potential to mitigate conflicts, feeding into the larger scheme of adaptive management
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