共查询到20条相似文献,搜索用时 78 毫秒
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构建一个综合的数值模型,用来处理植被地表径流与饱和地下水流之间的相互作用问题.综合了早先提出的准三维植被地表径流模型,与二维饱和地下水流模型建立起该数值模型.植被地表水流模型被构建为,二维浅水方程(SWE)显式的有限体积解,耦合了Navier-Stokes方程(NSE)隐式的有限差分解,得到了竖向速度的分布.地下水流模型是以二维饱和地下水流方程(SGE)显式的有限体积解为基础构建.通过在连续方程中引入源-汇项,达到植被地表径流和地下水流之间的相互作用.单一的规则将2个解紧密地耦合在一起.最后,应用4个案例来验证本综合模型,结果是令人满意的. 相似文献
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圆锥曲线之间的一个变换 总被引:1,自引:1,他引:0
文给出了圆锥曲线间的一个有趣变换,但只给出了由一种曲线变换为另一种曲线或它自身(如文中的定理3由椭圆变换为双曲线)。实际上,改变定理中两点A、A'的位置可以变换出各种不同的圆锥曲线(包括它自身)。下面以几个定理的形式具体给出这一变换的结论。 相似文献
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本文根据多晶金属变形的细观过程特征,将形变晶粒分为三类.提出塑性形变晶粒增殖的概念,并由此导出较为简洁的弹塑性本构关系.能对若干实验结果给出合理的解释.表明材料的宏观屈服、率相关和加工硬化等现象与形变晶粒演化的动力学过程密切相关. 相似文献
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把一个整体分为n份,其中至少有一份不少于整体的n分之一,也至少有一份不大于整体的n分之一。换成数学式,即若x_1,x_2,…,x_n为非负数,且x_1+x_2+…+x_n=1, 至少存在一个x_i≥1/n,j∈{1,2,…,n}; 至少存在一个x-j≤1/n,j∈{1,2,…,n}。证明简单,在此从略。这是整体与部分之间一个非常简单而明白的关系,而不少问题的证明都可以借助于这一关系。 相似文献
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A. Bonsignore G. Ferretti G. Magnani 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(1):43-54
Starting from a precise definition of friction torque when velocity vanishes that distinguishes the case of instantaneous zero crossing from that where the velocity is zero over a time interval, this paper proposes a compact analytical formulation of the classical discontinuous friction model that is useful for motion analysis. A finite state machine that allows a numerically robust computation of motion equations when velocity vanishes or motion restarts is then defined. Simulation results show that the discontinuous model can be seen as an asymptotic approximation, infinitely fast, of a recently proposed continuous, dynamic friction model. 相似文献
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A. D. Clayden 《The Journal of the Operational Research Society》1977,28(3):505-515
This model has been designed to assist decision making in the Health Services by predicting the effects on a local population of proposed policy decisions. Policy decisions are considered to: The model predicts the incidence of morbidity and mortality in a specified population and the changes in resource use over a period of years. Thus it is possible to see the long term effects of changes in population size and structure alongside the effects of management decisions on the use of health resources.The model has been designed principally for research purposes but has been used in the context of a health services management game. The validity of the model's predictions have yet to be tested. It is hoped to run the model in parallel with management decision making in a single health district in order to test the model's validity and improve its predictive ability. 相似文献
- 1Change the amount of certain resources available, e.g. manpower, hospital beds; or
- 2Alter the methods of using resources, e.g. changing the emphasis of health care to the community rather than the hospital; or
- 3Change the characteristics of illnesses, e.g. by vaccination or screening.
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The paper describes initial simulation work on various factors associated with production and inventory decisions. The machine shop model which was used comprised one machine only on which a small product range is manufactured. The effects of variations in output mix and demand levels on the rate of return on investment is examined. The necessary adjustments in stocking policy for an economic level of capacity utilization are indicated, and a "capacity profile" is produced which reveals the efficient operating frontier for the different cases. The direction of further experiments is indicated. 相似文献
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Bridget Eileen Tenner 《Annals of Combinatorics》2007,11(1):101-114
We classify finite posets with a particular sorting property, generalizing a result for rectangular arrays. Each poset is
covered by two sets of disjoint saturated chains such that, for any original labeling, after sorting the labels along both
sets of chains, the labels of the chains in the first set remain sorted. We also characterize posets with more restrictive
sorting properties.
Received October 19, 2005 相似文献
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使用双Lelel set方法来重新表示油藏模型特征,渗透率可以通过解无限制的Lagrangian最优化问题得到.对Lagrangian范函加上Level Set函数的限制之后,鞍点就可以通过算子分裂格式得到.数值模拟表明新算法是稳定高效的. 相似文献
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姚昌辉 《数学的实践与认识》2010,40(17)
使用双Level Set方法重新表示油藏模型特征中的渗透率,并且渗透率可以通过解一个转化过的最优化问题得到.这个最优化问题是一个无限制的Lagrangian型鞍点问题.在复杂区域的数值模拟表明使用算子分裂格式的Uzawas算法解这个鞍点问题比使用梯度下降格式的Uzawas算法高效稳定. 相似文献
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实践社群知识扩散的效率和效果影响实践社群的创新能力。通过考虑实践社群成员知识异质性对知识扩散的影响,引入知识生态位的观点,比较实践社群成员知识生态位的重叠程度,进而构建实践社群知识扩散模型,考虑实践社群成员间的相互作用,对知识扩散模型进行求解,得到相应的稳定均衡点并利用相图分析法进行验证,最后利用MATLAB进行数值仿真研究。结果表明:实践社群成员知识生态位的重叠程度对知识扩散效果有重要影响,实践社群成员间影响程度的大小对实践社群知识扩散模型均衡点有显著影响,实践社群成员知识表现为知识互补时,实践社群知识扩散的效率与效果最优。研究结果为促进实践社群知识扩散提供理论依据。 相似文献
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A discrete-event simulation model is being developed to provide information for national and regional health planners about the effect of different treatment policies and practices on the increasing numbers of patients with irreversible kidney failure. The simulation program, written in Pascal using Pascal-SIM, describes the activities of individual patients whose progress through treatment depends on their characteristics and treatment history, as well as on treatments availability. Programming techniques have been developed to cope with the multiple scheduling of patient entities and the resultant queue-management problems. In order to provide simulation runs on request, for any population group, appropriate data is selected from the European Dialysis and Transplant Association Registry data base for use in the simulation program. Results are shown on a computer screen while the simulation is running, and are saved for further analysis to provide feedback to the requesting organization. 相似文献
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本文从模糊理论的观点出发,研究了机械系统摩擦润滑耦合状态的特征参数,提出了摩擦润滑耦合状态模糊域特征参数建模及可视化的方法。 相似文献