41 resultados para RETC
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土壤水动力学参数的推导和土壤水分运动的数值模拟是研究土壤水分运动规律的两个重要部分,是农田节水灌溉自动化控制工程设计的理论依据。本文以曰光温室草甸棕壤的三种质地为研究对象,应用土壤转换函数理论和有限元法,通过RETC软件由土壤机械组成和容重两个基本物理性质指标推导其土壤水动力学参数;运用HYDRUS-2D软件对同一渗灌管埋深〔30cm)、3种管径、10种供水压力、6种初始土壤水势条件下的土壤水分运动进行了数值模拟;并对土壤水动力学参数推导和土壤水分运动数值模拟结果进行了实测验证。结果表明:(1)RETC和HYDRUS-2D是进行土壤水动力学参数推导和土壤水分运动数值模拟的有力工具。(2)土壤水动力学性质对渗灌条件下土壤水分运动速度具有显著的作用,最适宜渗灌的土壤是壤土,偏砂、偏虱质地次之。(3)渗灌的供水压力对三种质地土壤水分运动具有显著的影响。壤砂土、壤土和戮土三种质地土壤的适宜供水压力应分别不小于500cmH2O、700cmH2O、400cmH2O。(4)就内径为10mm、15mm和20mm渗灌管而言,渗灌管管径越大越有利于渗灌水向渗灌管四周土壤入渗,三种质地土壤渗灌均宜采用20mm管径渗管。(5)在壤砂质土和在较干燥的(土壤水势值<-1000cmH2O)壤质土和赫质土中,土壤初始水势值对渗灌土壤水分运动数值模拟结果的影响较小,而在较湿润的(土壤水势值>-1000cmH2O)壤质土和载土中,随着土壤初始水势值的降低,渗灌土壤水分运动速度(模拟)加快。
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土壤水动力学参数对指导农业生产、水利和水保工程设计是必不可少的。本文运用RETC软件,由土壤机械组成和容重推导出vanGenuchten模型的土壤持水曲线方程和土壤传导率方程,然后再对土壤持水曲线方程进行求导得出土壤比水容量方程,最后用实测结果进行验证。结果表明,土壤含水量θ(h)、土壤导水率K(h)计算值与测定值的相对误差均随着水势的降低而减小,土壤含水量的相对误差较土壤导水率低,且均小于10%,土壤导水率的相对误差范围在18%~39%。因此,运用RETC软件推导出的土壤水动力学参数还是可行的。
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This paper addresses the issue of access the industrial heritagerailway information integrating the EFNOB in the city of Bauru / SP, through the use of new technologiesinformation. For constitute a major challenge in gathering, organizing, scanning and providing such documentary collection, the research aims to organize and disseminate information document, supported by new access technologies, aiming to preserve and create conditions for setting up a database of documents and cartographic this collection. This research is part of our project entitled "EFNOB Bauru: Center for Memory and Virtual Information", which in turn is part of the larger project, called "EFNOB / Bauru, Km 0," FAPESP / CONDEPHAAT. One of the cornerstones of the work is to collect, treat, select and the heritagedisseminate of movable and immovable EFNOB through the creation of a MemoryCentre and Industrial HeritageRailwayInformation of EFNOB.
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Mode of access: Internet.
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Mode of access: Internet.
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National Highway Traffic Safety Administration, Washington, D.C.
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Mode of access: Internet.
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Mode of access: Internet.
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Mode of access: Internet.
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Mode of access: Internet.
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Mode of access: Internet.
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National Highway Traffic Safety Administration, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.