62,486 research outputs found

    Design and operational control of an AGV system

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    In this paper we first deal with the design and operational control of Automated Guided Vehicle (AGV) systems, starting from the literature on these topics. Three main issues emerge: track layout, the number of AGVs required and operational transportation control. An hierarchical queueing network approach to determine the number of AGVs is decribed. Also basic concepts are presented for the transportation control of both a job-shop and a flow-shop. Next we report on the results of a case study, in which track layout and transportation control are the main issues. Finally we suggest some topics for further research

    Manufacturing Processes Management with Usage of Simulation Tools

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    Simulace vĂœrobnĂ­ch procesĆŻ pomĂĄhĂĄ optimalizovat vĂœrobu, logistiku a dalĆĄĂ­ systĂ©my, dĂ­ky čemuĆŸ dochĂĄzĂ­ ke sniĆŸovĂĄnĂ­ nĂĄkladĆŻ a racionalizaci vnitropodnikovĂœch procesĆŻ. VyuĆŸitĂ­m diskrĂ©tnĂ­ simulace programu Witness Power with Ease se v diplomovĂ© prĂĄci optimalizuje logistickĂœ tok materiĂĄlu ve společnosti Hella Autotechnik, s.r.o. PrĂĄce pƙibliĆŸuje metody a jednotlivĂ© fĂĄze tvorby modelu včetně jeho validace a navrhuje vylepĆĄenĂ­, dĂ­ky kterĂ©mu by mělo dojĂ­t ke snĂ­ĆŸenĂ­ nĂĄkladĆŻ na dopravnĂ­ sluĆŸby o 24 400 Kč měsíčně.By optimizing the logistics, production and other systems the simulation can reduce costs and rationalise business processes. By use of discrete simulation in software Witness Power with Ease is in this diploma thesis optimised logistical flow of material in the company Hella Autotechnik, s.r.o. The thesis introduces methods and particular phases of creating the model including its validation. The proposal in the diploma work suggests the improvement to lower the costs for the transportation services by 24,400 CZK per month.

    Tasks, cognitive agents, and KB-DSS in workflow and process management

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    The purpose of this paper is to propose a nonparametric interest rate term structure model and investigate its implications on term structure dynamics and prices of interest rate derivative securities. The nonparametric spot interest rate process is estimated from the observed short-term interest rates following a robust estimation procedure and the market price of interest rate risk is estimated as implied from the historical term structure data. That is, instead of imposing a priori restrictions on the model, data are allowed to speak for themselves, and at the same time the model retains a parsimonious structure and the computational tractability. The model is implemented using historical Canadian interest rate term structure data. The parametric models with closed form solutions for bond and bond option prices, namely the Vasicek (1977) and CIR (1985) models, are also estimated for comparison purpose. The empirical results not only provide strong evidence that the traditional spot interest rate models and market prices of interest rate risk are severely misspecified but also suggest that different model specifications have significant impact on term structure dynamics and prices of interest rate derivative securities.

    A Model of R&D Valuation and the Design of Research Incentives

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    We develop a real options model of R&D valuation, which takes into account the uncertainty in the quality of the research output, the time and cost to completion, and the market demand for the R&D output. The model is then applied to study the problem of pharmaceutical under-investment in R&D for vaccines to treat diseases affecting the developing regions of the world. To address this issue, world organizations and private foundations are willing to sponsor vaccine R&D, but there is no consensus on how to administer the sponsorship effectively. Different research incentive contracts are examined using our valuation model. Their effectiveness is measured in the following four dimensions: cost to the sponsor, the probability of development success, the consumer surplus generated and the expected cost per person successfully vaccinated. We find that, in general, purchase commitment plans (pull subsidies) are more effective than cost subsidy plans (push subsidies), while extending patent protection is completely ineffective. Specifically, we find that a hybrid subsidy constructed from a purchase commitment combined with a sponsor co-payment feature produces the best results in all four dimensions of the effectiveness measure.

    The Logistic Principles for Fast Flexible Strategy Design of the Company in Crisis Time

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    The article deals with design of the logistic principles enabling an enterprise to create a strategy flexible in terms of business and marketing and stable and steady in terms of manufacturing. In order to create a strategy model the following principles can be applied: shortening the period of capacity planning combined with flexible planning, SYNCRO – MRP (Material Required Planning) principle, the application of forecasting in capacity planning, creation with partners of one of the cooperation forms such as supply chain, demand chain, lean supply chain, agile supply chain, leagile supply chain, and using the DBR (Drum Buffer Rope), APS (Advanced Planning System) and SCP (Supply Chain Planning) systems. The article describes application of this principle for model design of the flexible strategy for Chemosvit fólie a. s. company, and the results of this application in the crisis time 2009–2011.SYANCRO-MRP, capacity planning, forecasting, supply chain, demand chain

    Management of Production in Construction: A Theoretical View

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    The transformation view and the flow view are two major conceptualizations of production. The current practice in construction is based on the transformation view. However, the transformation view is an idealization, and in a complex production situation the associated idealization error may become large. This is exactly what happens in practice. Task management, based on the transformation view, assumes that certainty prevails in production. However, it is widely observed that, due to the inherent variability of production in construction, intended task management degenerates into mutual adjustment by teams on site. It is argued that the transformation view and the flow view should be synthesized into a new theoretical view on construction. The inherent causes of variability in construction can be explained and the countermeasures for eliminating variability or stemming its impact can be pinpointed by this new theoretical view. It is shown that the Last Planner method is compatible with this new view

    Tasks, cognitive agents, and KB-DSS in workflow and process management

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    The purpose of this paper is to propose a nonparametric interest rate term structure model and investigate its implications on term structure dynamics and prices of interest rate derivative securities. The nonparametric spot interest rate process is estimated from the observed short-term interest rates following a robust estimation procedure and the market price of interest rate risk is estimated as implied from the historical term structure data. That is, instead of imposing a priori restrictions on the model, data are allowed to speak for themselves, and at the same time the model retains a parsimonious structure and the computational tractability. The model is implemented using historical Canadian interest rate term structure data. The parametric models with closed form solutions for bond and bond option prices, namely the Vasicek (1977) and CIR (1985) models, are also estimated for comparison purpose. The empirical results not only provide strong evidence that the traditional spot interest rate models and market prices of interest rate risk are severely misspecified but also suggest that different model specifications have significant impact on term structure dynamics and prices of interest rate derivative securities.

    Observing the clouds : a survey and taxonomy of cloud monitoring

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    This research was supported by a Royal Society Industry Fellowship and an Amazon Web Services (AWS) grant. Date of Acceptance: 10/12/2014Monitoring is an important aspect of designing and maintaining large-scale systems. Cloud computing presents a unique set of challenges to monitoring including: on-demand infrastructure, unprecedented scalability, rapid elasticity and performance uncertainty. There are a wide range of monitoring tools originating from cluster and high-performance computing, grid computing and enterprise computing, as well as a series of newer bespoke tools, which have been designed exclusively for cloud monitoring. These tools express a number of common elements and designs, which address the demands of cloud monitoring to various degrees. This paper performs an exhaustive survey of contemporary monitoring tools from which we derive a taxonomy, which examines how effectively existing tools and designs meet the challenges of cloud monitoring. We conclude by examining the socio-technical aspects of monitoring, and investigate the engineering challenges and practices behind implementing monitoring strategies for cloud computing.Publisher PDFPeer reviewe
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