6 resultados para Operational research

em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland


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Preference relations, and their modeling, have played a crucial role in both social sciences and applied mathematics. A special category of preference relations is represented by cardinal preference relations, which are nothing other than relations which can also take into account the degree of relation. Preference relations play a pivotal role in most of multi criteria decision making methods and in the operational research. This thesis aims at showing some recent advances in their methodology. Actually, there are a number of open issues in this field and the contributions presented in this thesis can be grouped accordingly. The first issue regards the estimation of a weight vector given a preference relation. A new and efficient algorithm for estimating the priority vector of a reciprocal relation, i.e. a special type of preference relation, is going to be presented. The same section contains the proof that twenty methods already proposed in literature lead to unsatisfactory results as they employ a conflicting constraint in their optimization model. The second area of interest concerns consistency evaluation and it is possibly the kernel of the thesis. This thesis contains the proofs that some indices are equivalent and that therefore, some seemingly different formulae, end up leading to the very same result. Moreover, some numerical simulations are presented. The section ends with some consideration of a new method for fairly evaluating consistency. The third matter regards incomplete relations and how to estimate missing comparisons. This section reports a numerical study of the methods already proposed in literature and analyzes their behavior in different situations. The fourth, and last, topic, proposes a way to deal with group decision making by means of connecting preference relations with social network analysis.

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Numerical weather prediction and climate simulation have been among the computationally most demanding applications of high performance computing eversince they were started in the 1950's. Since the 1980's, the most powerful computers have featured an ever larger number of processors. By the early 2000's, this number is often several thousand. An operational weather model must use all these processors in a highly coordinated fashion. The critical resource in running such models is not computation, but the amount of necessary communication between the processors. The communication capacity of parallel computers often fallsfar short of their computational power. The articles in this thesis cover fourteen years of research into how to harness thousands of processors on a single weather forecast or climate simulation, so that the application can benefit as much as possible from the power of parallel high performance computers. The resultsattained in these articles have already been widely applied, so that currently most of the organizations that carry out global weather forecasting or climate simulation anywhere in the world use methods introduced in them. Some further studies extend parallelization opportunities into other parts of the weather forecasting environment, in particular to data assimilation of satellite observations.

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Abstract The research problem in the thesis deals with improving the responsiveness and efficiency of logistics service processes between a supplier and its customers. The improvement can be sought by customizing the services and increasing the coordination of activities between the different parties in the supply chain. It is argued that to achieve coordination the parties have to have connections on several levels. In the framework employed in this research, three contexts are conceptualized at which the linkages can be planned: 1) the service policy context, 2) the process coordination context, and 3) the relationship management context. The service policy context consists of the planning methods by which a supplier analyzes its customers' logistics requirements and matches them with its own operational environment and efficiency requirements. The main conclusion related to the service policy context is that it is important to have a balanced selection of both customer-related and supplier-related factors in the analysis. This way, while the operational efficiency is planned a sufficient level of service for the most important customers is assured. This kind of policy planning involves taking multiple variables into the analysis, and there is a need to develop better tools for this purpose. Some new approaches to deal with this are presented in the thesis.The process coordination context and the relationship management context deal with the issues of how the implementation of the planned service policies can be facilitated in an inter-organizational environment. Process coordination includes typically such mechanisms as control rules, standard procedures and programs, but inhighly demanding circumstances more integrative coordination mechanisms may be necessary. In the thesis the coordination problems in third-party logistics relationship are used as an example of such an environment. Relationship management deals with issues of how separate companies organize their relationships to improve the coordination of their common processes. The main implication related to logistics planning is that by integrating further at the relationship level, companies can facilitate the use of the most efficient coordination mechanisms and thereby improve the implementation of the selected logistics service policies. In the thesis, a case of a logistics outsourcing relationship is used to demonstrate the need to address the relationship issues between the service provider andthe service buyer before the outsourcing can be done.The dissertation consists of eight research articles and a summarizing report. The principal emphasis in the articles is on the service policy planning context, which is the main theme of six articles. Coordination and relationship issues are specifically addressed in two of the papers.

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This thesis concentrates on studying the operational disturbance behavior of machine tools integrated into FMS. Operational disturbances are short term failures of machine tools which are especially disruptive to unattended or unmanned operation of FMS. The main objective was to examine the effect of operational disturbances on reliability and operation time distribution for machine tools. The theoretical part of the thesis covers the fimdamentals of FMS relating to the subject of this study. The concept of FMS, its benefits and operator's role in FMS operation are reviewed. The importance of reliability is presented. The terms describing the operation time of machine tools are formed by adopting standards and references. The concept of failure and indicators describing reliability and operational performance for machine tools in FMSs are presented. The empirical part of the thesis describes the research methodology which is a combination of automated (ADC) and manual data collection. By using this methodology it is possible to have a complete view of the operation time distribution for studied machine tools. Data collection was carried out in four FMSs consisting of a total of 17 machine tools. Each FMS's basic features and the signals of ADC are described. The indicators describing the reliability and operation time distribution of machine tools were calculated according to collected data. The results showed that operational disturbances have a significant influence on machine tool reliability and operational performance. On average, an operational disturbance occurs every 8,6 hours of operation time and has a down time of 0,53 hours. Operational disturbances cause a 9,4% loss in operation time which is twice the amount of losses caused by technical failures (4,3%). Operational disturbances have a decreasing influence on the utilization rate. A poor operational disturbance behavior decreases the utilization rate. It was found that the features of a part family to be machined and the method technology related to it are defining the operational disturbance behavior of the machine tool. Main causes for operational disturbances were related to material quality variations, tool maintenance, NC program errors, ATC and machine tool control. Operator's role was emphasized. It was found that failure recording activity of the operators correlates with the utilization rate. The more precisely the operators record the failure, the higher is the utilization rate. Also the FMS organizations which record failures more precisely have fewer operational disturbances.

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The aim of the present dissertation is to investigate the marketing culture of research libraries in Finland and to understand the awareness of the knowledge base of library management concerning modern marketing theories and practices. The study was based onthe notion that a leader in an organisation can have large impact on its culture. Therefore, it was considered important to learn about the market orientation that initiates at the top management and flows throughout the whole organisationthus resulting in a particular kind of library culture. The study attempts to examine the marketing culture of libraries by analysing the marketing attitudes, knowledge (underlying beliefs, values and assumptions), behaviour (market orientation), operational policies and activities, and their service performance (customer satisfaction). The research was based on the assumption that if the top management of libraries has market oriented behaviour, then their marketing attitudes, knowledge, operational policies and activities and service performance should also be in accordance. The dissertation attempts to connect all these theoretical threads of marketing culture. It investigates thirty three academic and special libraries in the south of Finland. The library director and three to ten customers from each library participated as respondents in this study. An integrated methodological approach of qualitative as well as quantitative methods was used to gain knowledge on the pertinent issues lying behind the marketing culture of research libraries. The analysis of the whole dissertation reveals that the concept of marketing has very varied status in the Finnish research libraries. Based on the entire findings, three kinds of marketing cultures were emerged: the strong- the high fliers; the medium- the brisk runners; and the weak- the slow walkers. The high fliers appeared to be modern marketing believers as their marketing approach was customer oriented and found to be closer to the emerging notions of contemporary relational marketing. The brisk runners were found to be traditional marketing advocates as their marketing approach is more `library centred¿than customer defined and thus is in line of `product orientation¿ i.e. traditional marketing. `Let the interested customers come to the library¿ was appeared to be the hallmark of the slow walkers. Application of conscious market orientation is not reflected in the library activities of the slow walkers. Instead their values, ideology and approach to serving the library customers is more in tuneof `usual service oriented Finnish way¿. The implication of the research is that it pays to be market oriented which results in higher customer satisfaction oflibraries. Moreover, it is emphasised that the traditional user based service philosophy of Finnish research libraries should not be abandoned but it needs to be further developed by building a relational based marketing system which will help the libraries to become more efficient and effective from the customers¿ viewpoint. The contribution of the dissertation lies in the framework showing the linkages between the critical components of the marketing culture of a library: antecedents, market orientation, facilitators and consequences. The dissertationdelineates the significant underlying dimensions of market-oriented behaviour of libraries which are namely customer philosophy, inter-functional coordination,strategic orientation, responsiveness, pricing orientation and competition orientation. The dissertation also showed the extent to which marketing attitudes, behaviour, knowledge were related and impact of market orientation on the serviceperformance of libraries. A strong positive association was found to exist between market orientation and marketing attitudes and knowledge. Moreover, it also shows that a higher market orientation is positively connected with the service performance of libraries, the ultimate result being higher customer satisfaction. The analysis shows that a genuine marketing culture represents a synthesis of certain marketing attitudes, knowledge and of selective practices. This finding is particularly significant in the sense that it manifests that marketing culture consists of a certain sets of beliefs and knowledge (which form a specific attitude towards marketing) and implementation of a certain set of activities that actually materialize the attitude of marketing into practice (market orientation) leading to superior service performance of libraries.

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Finnish Defence Studies is published under the auspices of the National Defence College, and the contributions reflect the fields of research and teaching of the College. Finnish Defence Studies will occasionally feature documentation on Finnish Security Policy. Views expressed are those of the authors and do not necessarily imply endorsement by the National Defence College.