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本文根据Philip、DeVries和Milly的多孔介质中水、汽、热传递的理论,给出了冬小麦苗期松土耕作时的土壤内水热分布的耦合模型,将其数值解结果与实测值进行了对比验证,表明该模型较准确地模拟了土壤水热动态。对土壤内水分动态的模拟表明,松土时土壤内水汽流动在整体水分流动中所占比例较小,但用等温模型与水、汽、热耦合模型模拟,仅开始时用等温模型简化对水分流动的差异较小,随着进一步蒸发,差异将较大,需考虑水汽运动的热效应。因此,在松土保墒条件下,连续蒸发时用非等温模型模拟土壤水分运动状态是十分必要的。 相似文献
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本文利用禹城综合试验站土壤-植物-大气连续体系综合观测场冬小麦田实测资料,对“SPAC系统中水热、CO2通量与光合作用的综合模型(Ⅰ)模型建立”一文所建立的模型土壤水分动态、蒸发蒸腾和冠层CO2通量等功能进行了验证,利用波文比观测水汽通量结果、土壤水分剖面监测结果分别与对模拟计算腾发量和土壤水分剖面的验证结果表明,模拟计算的腾发量和土壤水分剖面是比较准确的;将模拟的光合作用过程中的CO2通量与实测值对比表明,模拟值与实测值的变化趋势是一致的,但是数据上存在一定的差异,模拟光合作用过程和强度符合一般规律,总体说明,所建立的系统模型在上述功能的模拟上是可行的。 相似文献
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本文利用禹城综合试验站土壤-植物-大气连续体系统综合观测场冬小麦田间实测资料,对“SPAC系统中水热、CO2通量与光合作用的综合模型(Ⅰ)模型建立”一文所建立的模拟土壤水分动态、蒸发蒸腾和冠层CO2通量等功能进行了验证。利用波文比观测水汽通量结果、土壤水分剖面监测结果分别对模拟计算腾发量和土壤水分剖面的验证结果表明,模拟计算的腾发量和土壤水分剖面是比较准确的;将模拟的光合作用过程中的CO2通量与实测值对比表明,模拟值与实测值的变化趋势是一致的,但是数量上存在一定的差异。模拟光合作用过程和强度符合一般规律。总体说明,所建立的系统模型在上述功能的模拟上是可行的。 相似文献
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地下滴灌条件下水热运移数学模型与验证 总被引:4,自引:0,他引:4
基于土壤水、热运动基本方程,结合地下滴灌水分运动特点,建立了地下滴灌水热运移数学模型。利用HYDRUS-2D软件对模型进行了求解,并用田间实测数据进行验证。模拟和验证结果表明,模型对地下滴灌条件下的土壤水分和土壤温度运移变化动态的模拟效果较好,该水热运移数学模型可以用来监测和调控作物生长所需的土壤水、热环境条件。模拟值和实测值的结果对比表明,上层土壤的水分和温度的模拟值较下层土壤值差异较明显,且数值波动大,主要原因是上层土壤易受到土壤蒸发和大气温度剧烈波动的影响。 相似文献
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本文利用禹城综合试验站土壤 -植物 -大气连续体系统综合观测场冬小麦田间实测资料 ,对“SPAC系统中水热、CO2 通量与光合作用的综合模型 (Ⅰ )模型建立”一文所建立的模拟土壤水分动态、蒸发蒸腾和冠层CO2 通量等功能进行了验证 .利用波文比观测水汽通量结果、土壤水分剖面监测结果分别对模拟计算腾发量和土壤水分剖面的验证结果表明 ,模拟计算的腾发量和土壤水分剖面是比较准确的 ;将模拟的光合作用过程中的CO2通量与实测值对比表明 ,模拟值与实测值的变化趋势是一致的 ,但是数量上存在一定的差异 .模拟光合作用过程和强度符合一般规律 .总体说明 ,所建立的系统模型在上述功能的模拟上是可行的 相似文献
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本文在一维黄土土柱试验系统上,进行了弥散试验及重金属的运移规律试验,由试验得知:虽然氯离子为隋性离子,但黄土土壤对其仍具有一定吸附能力,所以利用氯离子来测定黄土区的弥散系数会存在误差,使得到的弥散度偏大。通过重金属锌在一维黄土土柱中的运移试验,确定出用以描述黄土土壤对重金属锌吸附过程的Freunlich等温模型的有关参数,同时也证实应用Freunlich等温模型来模拟黄土土壤对重金属锌吸附的合理性。并由试验看出锌在黄土体中的运移速度是相当慢的。 相似文献
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地膜覆盖条件下土壤水及溶质运移规律的室内试验研究 总被引:5,自引:0,他引:5
针对黄淮海地区大面积种植棉花并采用地膜覆盖这一现状,采用室内模拟试验法,研究了地膜覆盖后土壤剖面上的水盐运移特点和规律.研究结果表明,在盐碱地上采用地膜覆盖,一方面可以减少土壤水分的蒸发,提高表层土壤的湿度;一方面由于通过土壤表层蒸发的水分减少,土壤中的盐分的表聚作用大为减弱,抑制了土壤返盐过程. 相似文献
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Optimal Management of Coastal Aquifers Using Linked Simulation Optimization Approach 总被引:4,自引:3,他引:1
Saltwater intrusion management models can be used to derive optimal and efficient management strategies for controlling saltwater intrusion in coastal aquifers. To obtain physically meaningful optimal management strategies, the physical processes involved need to be simulated while deriving the management strategies. The flow and transport processes involved in coastal aquifers are difficult to simulate especially when the density-dependent flow and transport processes need to be modeled. Incorporation of this simulation model within an optimization-based management model is very complex and difficult. However, as an alternative, it is possible to link a simulation model externally with an optimization-based management model. The GA-based optimization approach is especially suitable for externally linking the numerical simulation model within the optimization model. Further efficiency in computational procedure can be achieved for such a linked model, if the simulation process can be simplified by approximation, as very large number of iterations between the optimization and simulation model is generally necessary to evolve an optimal management strategy. A possible approach for approximating the simulation model is to use a trained Artificial Neural Network (ANN) as the approximate simulator. Therefore, an ANN model is trained as an approximator of the three dimensional density-dependent flow and transport processes in a coastal aquifer. A linked simulation – optimization model is then developed to link the trained ANN with the GA-based optimization model for solving saltwater management problems. The performance of the developed optimization model is evaluated using an illustrative study area. The evaluation results show the potential applicability of the developed methodology using a GA- and ANN-based linked optimization – simulation model for optimal management of coastal aquifer. 相似文献
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加里宁-米留柯夫型流域地貌汇流模型 总被引:3,自引:0,他引:3
本文根据概念性流域地貌汇流模型的一般理论,建立了加里宁-米留柯夫型流域地貌汇流模型、推导了三级、四级和五级流域的瞬时单位线,并分析了模型参数对瞬时单位线的影响.用内罚函数法估计模型参数.通过实例检验,模型拟合精度较高. 相似文献
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《Water science and technology》1998,37(12):363-370
Three different methodologies are assessed which provide predictions of the hydraulic load to the treatment plant one hour ahead. The three models represent three different levels of complexity ranging from a simple regression model over an adaptive grey-box model to a complex hydrological and full dynamical wave model (Chow et al., 1988). The simple regression model is estimated as a transfer function model of rainfall intensity to influent flow. It also provides a model for the base flow. The grey-box model is a state space model which incorporates adaptation to the dry weather flow as well as the rainfall runoff. The full dynamical flow model is a distributed deterministic model with many parameters, which has been calibrated based on extensive measurement campaigns in the sewer system. The three models are compared by the ability to predict the hydraulic load one hour ahead. Five rain events in a test period are used for evaluating the three different methods. The predictions are compared to the actual measured flow at the plant one hour later. The results show that the simple regression model and the adaptive grey-box model which are identified and estimated on measured data perform significantly better than the hydrological and full dynamical flow model which is not identifiable and needs calibration by hand. For frontal rains no significant difference in the prediction performance between the simple regression model and the adaptive grey-box model is observed. This is due to a rather uniform distribution of frontal rains. A single convective rain justifies the adaptivity of the grey-box model for non-uniformly distributed rain, i.e. the predictions of the grey-box model were significantly better than the predictions of the simple regression model for this rain event. In general, models for model-based predictive control should be kept simple and identifiable from measured data. 相似文献
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在混凝土坝裂缝开度预测中得到了广泛应用的统计回归模型仍存在不足。首先,对小容量样本的观测时间序列难以建立有效的统计回归模型;其次,预测模型未能考虑残差项,而残差项包含了裂缝发展演变的海量信息,为了准确预测裂缝开度还须在预测模型中纳入残差项。同时,统计回归模型的残差序列中存在混沌成分,残差项受到某种动力特性支配,故基于混沌理论对残差项进行推求,建立了统计与混沌混合预测模型。采用基于Legendre多项式的RLS(递推最小二乘法)自适应预测算法,提出了针对小容量样本观测数据时间序列的实时预测模型以及针对大容量样本观测数据时间序列的统计回归-Legendre多项式残差预测模型。最后,结合陈村重力拱坝在105 m高程的裂缝开度实测数据,对裂缝开度实时预测模型以及统计回归-Legendre多项式组合模型分别进行了检验,结果表明模型具有良好的预测精度,可为工程的安全运行管理工作提供一定的技术支持。 相似文献
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本研究是将熵值法与属性识别模型相结合,建立了桃山水库基于熵权的属性识别模型,应用模型对桃山水库的富营养化进行评价;并对模型评价结果进行验证,模型预测精度良好。 相似文献
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Constructing a robust hydraulic network model is vitally important, but a time-consuming task. Over last two decades, several
approaches using optimization techniques have been developed for identifying model parameters. Although most of the methods
can make the model agree with field observations, few are able to achieve a good level of accuracy in terms of determining
the correct model parameters for a water distribution system. The previously developed methods appear to be lacking versatility
for users to specify calibration tasks given real data for a real system. This paper proposes a comprehensive framework for
evolving a hydraulic network model. Calibration tasks can be specified according to data availability and model application
requirements. It allows an engineer to (1) flexibly choose any combination of the model parameters such as pipe roughness,
junction demand and link (pipes, valves and pumps) operational status; (2) easily aggregate model parameters to reduce the
problem dimension for expeditious calculation and (3) consistently specify boundary conditions and junction demand loadings
that are corresponding to field data collection. A model calibration is then defined as an implicit nonlinear optimization
problem, which is solved by employing a competent evolutionary algorithm. With this methodology, a modeler can be fully assisted
to carry out not only a single parameter optimization run, but also a variety of calibration tasks in a progressive manner
according to practical system conditions, thus it is possible to achieve a good model calibration with high level of confidence.
The method has been applied to the model of a municipal water system to demonstrate the efficacy and robustness of the evolutionary
modeling practices. 相似文献
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应用新安江模型与垂向混合产流模型对闽江流域干流以上的15个子流域进行了模拟验证,进一步论证了这两种概念性流域水文模型结构的合理性,并得出了如下结论:大闽江流域,新安江模型与垂向混合产流模型都适用,且均能取得良好的效果。由于不同的洪水预报模型考虑产流机理的不同,采用的结构与参数不同,对不同洪水特征的计算结果也有差别,在实际使用中,设置不同结构的洪水预报模型是必要而且是有效的。同时,还对历史洪水根据其涨洪前段的实测流量过程与模型计算流量过程的确定性系数最大作为选择模型的标准,进行模型选择模拟预报。由此还得出另一个结论:在实时洪水预报中,根据不同的预知信息实时选择最佳的模型,能提高洪水预报的精度。 相似文献