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采用SWOT分析法作为西部公路发展策略的制定方法,在对西部公路交通系统的内外部环境影响因素归纳、剖析的基础上,给出了西部公路内外部环境分析与评价的方法,按重要性确定了西部公路发展环境的优势(S)与劣势(W)、机会(O)和威胁(T)因素,并采用定量与定性方法相结合提出了西部公路发展的建议策略,为西部公路发展在策略层面提供了理论指导。 相似文献
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基于交易费用的物流运作模式研究 总被引:3,自引:0,他引:3
从交易费用理论及物流运作模式着手,探讨了市场采购、物流自营,物流外包与物流内包的适应环境及运作对象。即:对于一般的物流活动应该从市场上进行采购,对于集成化的物流服务应该采用外部外包,当第三方物流市场走向垄断时,要积极寻求物流内包。 相似文献
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Transfer functions are often used together with a wave spectrum for analysis of wave–ship interactions, where one application addresses the prediction of wave-induced motions or other types of global responses. This paper presents a simple and practical method which can be used to tune the transfer function of such responses to facilitate improved prediction capability. The input to the method consists of a measured response, i.e. time series sequences from a given sensor, the 2D wave spectrum characterising the seaway in which the measurements are taken, and an initial estimate of the transfer function for the response in study. The paper presents results obtained using data from an in-service container ship. The 2D wave spectra are taken from the ERA5 database, while the transfer function is computed by a simple closed-form expression. The paper shows that the application of the tuned transfer function leads to predictions which are significantly improved compared to using the transfer function without tuning. 相似文献
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本文采用有限元软件ABAQUS建立了船舶撞击高桩码头群桩的空间有限元模型。通过计算评估了撞击力、桩体刚度、撞击位置和撞击角度下对群桩结构损伤位置的影响。基于人工神经网络(ANN)方法,对不同参数组合下的群桩结构损伤位置进行了预测,并对ANN方法的可行性进行了评估。 相似文献
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Environmental contours are often applied in probabilistic structural reliability analysis to identify extreme environmental conditions that may give rise to extreme loads and responses. They facilitate approximate long term analysis of critical structural responses in situations where computationally heavy and time-consuming response calculations makes full long-term analysis infeasible. The environmental contour method identifies extreme environmental conditions that are expected to give rise to extreme structural response of marine structures. The extreme responses can then be estimated by performing response calculations for environmental conditions along the contours.Response-based analysis is an alternative, where extreme value analysis is performed on the actual response rather than on the environmental conditions. For complex structures, this is often not practical due to computationally heavy response calculations. However, by establishing statistical emulators of the response, using machine learning techniques, one may obtain long time-series of the structural response and use this to estimate extreme responses.In this paper, various contour methods will be compared to response-based estimation of extreme vertical bending moment for a tanker. A response emulator based on Gaussian processes regression with adaptive sampling has been established based on response calculations from a hydrodynamic model. Long time-series of sea-state parameters such as significant wave height and wave period are used to construct N-year environmental contours and the extreme N-year response is estimated from numerical calculations for identified sea states. At the same time, the response emulator is applied on the time series to provide long time-series of structural response, in this case vertical bending moment of a tanker. Extreme value analysis is then performed directly on the responses to estimate the N-year extreme response. The results from either method will then be compared, and it is possible to evaluate the accuracy of the environmental contour method in estimating the response. Moreover, different contour methods will be compared. 相似文献
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近几年来,我国山区高速建设里程日益增加.因受复杂地形、地质条件的限制,山区高速的外业勘察具有其独有的关键技术难点,应在普通建设条件下的作业内容、作业方式的基础上,采取针对性的对策措施,确保外勘资料满足设计需求. 相似文献