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Chunyang Yu Wei Zhang Xun Xu Yangjian Ji Shiqiang Yu 《Journal of Intelligent Manufacturing》2018,29(6):1351-1361
Cloud manufacturing (CMfg) promotes a dynamic distributed manufacturing environment by connecting the service providers and manages them in a centralized way. Due to the distinct production capabilities, the service providers tend to be delegated services of different granularities. Meanwhile, users of different types may be after services of different granularities. A traditional aggregate production planning method is often incapable of dealing with type of problems. For this reason, a multi-level aggregate service planning (MASP) methodology is proposed. The MASP service hierarchy is presented, which integrates the services of different granularities into a layered structure. Based on this structure, one of data mining technologies named time series is introduced to provide dynamic forecast for each layer. In this way, MASP can not only deal with the services of multi-granularity, but also meet the requirements of all related service providers irrespective of their manufacturing capabilities. A case study has been carried out, showing how MASP can be applied in a CMfg environment. The results of the prediction are considered reliable as the order of magnitude of the production for each service layer is much greater than that of the corresponding mean forecast error. 相似文献
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当复杂形式的建筑设计日益普遍,几何学对于建筑师理解复杂建筑形体的操作实质变得前所未有的重要,并以此催发几何学与建筑学关联性的重新审视。本文从梳理两者关系的演变历程出发,分析了当代数字化建筑实践的4种几何建构策略——几何生形、几何转化、协同模拟和几何重构,并结合具体案例研究,指出面向建筑本体需求的数字化几何思维是建筑学传统的回归,可以为数字化建筑设计提供更为合理的认识和参考。 相似文献
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Lead and lead-bismuth eutectic (LBE) alloy have been increasingly receiving attention as heavy liquid metal coolants (HLMC) for future nuclear energy systems. The compatibility of structural materials and components with lead-bismuth eutectic liquid at high temperature is one of key issues for the commercialization of lead fast reactors. In the present study, the corrosion behaviors of iron-based alumina-forming alloys (Kanthal-AF®, PM2000, MA956) were investigated by exposing to stagnant LBE environments at 500 °C and 550 °C for up to 500 h. After exposures, the thickness and chemistry of the oxide layer on the specimens were analyzed by scanning electron microscopy, scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. As a result, the oxide characteristics and the corrosion resistance were compared. In this study, it was shown that the corrosion resistance of FeCrAl ODS steels (PM2000, MA956) are superior to that of FeCrAl ferritic steel (Kanthal-AF®) in higher temperature LBE. 相似文献
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基于Matlab软件开发了自动识别气液两相流界面程序,程序可获得气液界面变化、汽膜厚度、汽膜脱离周期和汽膜法向速度等特征。利用该程序对沟槽结构加热表面朝下布置时,在不同倾角、不同热流密度下的汽泡动态数据进行了处理和分析。结果表明:加热表面朝下发生核态沸腾时,汽膜厚度随热流密度的增大而增大,汽泡脱离周期随热流密度的增大先减小,而后维持在一稳定值;汽膜脱离周期随倾角的增大而减小,倾角为5°时的汽膜脱离周期稳定在0.27 s左右。当发生沸腾危机时,汽膜厚度迅速减小,这可作为动态监测加热表面沸腾状态的依据。 相似文献
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The current solution for the spent fuel, high-level and long-lived radioactive waste is to store them at surface facilities from which they will be subsequently moved to a deep repository. No such repositories are in operation currently but several such facilities are close to the construction phase. A deep repository can be situated in several types of geological conditions including clay formations, salt sediments, argillites and tuffitic and granitic rocks. The character of the host rock is the key factor determining the design and specific requirements of individual components of such a facility. The future potential retrieval of canisters containing nuclear waste from the repository is a further influential factor. The reason for retrieval of containers lies in the development of fast reactors and increased interest for spent fuel reprocessing. Naturally, the decision as to whether retrievability is technically feasible must be made before finalising the design and construction process of the repository. If the decision is made to retrieve, a design which will include all the relevant safety aspects for the potential retrieval of canisters must be determined. The lay-out of the repository, the materials to be used and the design of the various structures of the facility (e.g. access tunnels, disposal shafts, buffer and backfill) are not the only issues to be addressed. The long-term stability of the system as a whole, i.e. of all the components, is crucial. Depending on the disposal concept chosen, the thermal load generated by the waste in the disposal container, saturation by water from the surrounding environment and the loading of the host rock massif will constitute the main processes which will affect the behaviour, safety and future functioning of the repository from the civil engineering point of view. The long-term stability of the lining of disposal galleries is a basic precondition for the safe removal of spent nuclear waste from deep underground repositories. The stability problems of tunnel linings exposed to long-term thermal load have not yet been properly addressed and form the subject of the European TIMODAZ project (Thermal Impact on the Damaged Zone around a Radioactive Waste Disposal in Clay Host Rocks) and also supported by the “Complex System of Methods for Directed Design and Assessment of Functional Properties of Building Materials” project. This paper describes the design, construction and currently available results of a 1:1 scale “in situ” disposal tunnel model which has been built at the Josef Underground Educational Facility in the Czech Republic. 相似文献