共查询到18条相似文献,搜索用时 109 毫秒
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靖西天然气管道是重要输气干线,准确预测需求负荷变化情况,确保管道安全、平稳、高效供气意义重大。文中以灰色理论为基础,利用管道历年气量数据建立灰色预测的GM(1,1)模型,采用后验差检验对预测模型进行检验,并对该管道未来用气需求量进行预测。计算结果显示:灰色GM(1,1)模型预测结果与实际结果具有较好的一致性,精度能够满足实际应用的要求,预测结果对靖西管道运行管理具有一定的借鉴作用。 相似文献
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文章在传统的灰色模型和马尔柯夫模型的基础上,提出了动态无偏灰色马尔柯夫模型,阐述了该模型的建立方法,并采用这三种模型对我国铁路客运量进行了预测,对比结果表明动态无偏灰色马尔柯夫模型的拟合效果较好,预测精度较高,是一种行之有效的预测方法。 相似文献
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原油结蜡是影响管道安全、经济和高效运行的一个重要因素。为了对输油管道的结蜡状况进行预测,掌握输油管道结蜡的基本规律,应用灰色系统理论中的模型对输油管道结蜡速度和结蜡厚度等指标的实际统计数据进行了灰色动态拟合,建立了相应的灰色微分方程和时间响应函数。结果表明:残差小于2%,模型精度满足工程实际需要。 相似文献
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文章针对重庆高家花园嘉陵江大桥实时健康监测系统的挠度长期监测数据,根据监测信息的时间序列呈季节、循环等非平稳状态特点,介绍采用ARMA时间序列预测模型,对挠度监测数据中所包含的外荷载的变化趋势及结构抗力的衰变信息进行动态预测,同时建立了结构外效应的预测函数。结果表明,采用低阶模型能对挠度监测值进行较好的动态预测。 相似文献
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长输天然气与城市燃气管道风险评价指标体系比较分析 总被引:2,自引:0,他引:2
长输天然气管道和城市燃气管道都是输气管道系统的重要组成部分,但是由于它们所处的位置和经过的区域大不相同,因此二者的风险有很大的不同。文中以《管道风险管理手册》为基础,结合半定量风险评价法中的管道指数法,通过比较长输天然气与城市燃气管道风险评价的指标体系,分析了它们之间的区别,对城市燃气管道的风险评价有一定的指导意义,为其风险评价提供了依据。 相似文献
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Joan-Manuel F. Mendoza Jordi Oliver-Solà Xavier Gabarrell Joan Rieradevall Alejandro Josa 《Transportation Research Part D: Transport and Environment》2012,17(6):442-450
This paper examines the relevance of incorporating comprehensive life-cycle environmental data into the design and management of pedestrian pavements to minimize the impact on the built environment. The overall primary energy demand and global warming potential of concrete, asphalt and granite sidewalks are assessed. A design with a long functional lifetime reduces its overall primary energy demand and global warming potential due to lower maintenance and repair requirements. However, long-lived construction solutions do not ensure a lower life-cycle primary energy demand and global warming potential than for shorter-lived designs; these values depend on the environmental suitability of the materials chosen for paving. Asphalt sidewalks reduce long-term global warming potential under exposure conditions where the functional lifetime of the pavements is less than 15 years. In places where it is known that a concrete sidewalk can have a life of at least 40 years, a concrete sidewalk is the best for minimizing both long-term primary energy demand and global warming potential. Granite sidewalks are the largest energy consumers and greenhouse gas contributors. 相似文献
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Carsharing has become an important addition to existing mobility services over the last years. Today, several different systems are operating in many big cities. For an efficient and economic operation of any carsharing system, the identification of customer demand is essential. This demand is investigated within the presented research by analyzing booking data of a German free-floating carsharing system.The objectives of this paper are to describe carsharing usage and to identify factors that have an influence on the demand for carsharing. Therefore, the booking data are analyzed for temporal aspects, showing recurring patterns of varying lengths. The spatial distribution of bookings is investigated using a geographic information system and indicates a relationship between city structure and areas with high demand for carsharing. The temporal and spatial facets are then combined by applying a cluster analysis to identify groups of days with similar spatial booking patterns and show asymmetries in the spatiotemporal distribution of vehicle supply and demand.Influences on demand can be either short-term or long-term. The paper shows that changes in the weather conditions are a short-term influence as users of free-floating carsharing react to those. Furthermore, the application of a linear regression analysis reveals that socio-demographic data are suitable for making long-term demand predictions since booking numbers show quite a strong correlation with socio-demography, even in a simple model. 相似文献